[Requirements for low vision magnification aids in age-related macular degeneration: Data from the Tübingen low vision clinic (comparison of 2007-2011 with 1999-2005)]

BACKGROUND

The purpose of this study was to investigate if there has been a change in requirements for low vision magnification aids in recent years.

PATIENTS AND METHODS

The collective data from age-related macular degeneration (AMD) patients from the Tübingen low vision clinic from the years 2007-2011 were compared with the patient collective from the years 1999-2005. Magnification needs and the prescribed magnifying aids for reading in the categories magnifying spectacles, hand-held magnifiers, monocular telescopes, electronic magnifiers and electronic reading devices were evaluated. In addition patients from 2010 and 2011 were divided into dry and neovascular AMD and the prescribed magnification aids were compared for these AMD forms.

RESULTS

There was no significant change in in the prescribed magnification reading aids for AMD patients between the years 1999-2005 and 2007-2011. An electronic magnifier was prescribed most often (both collectives 43 %), followed by hand-held magnifiers (32 and 29.5 %, respectively) and magnifying spectacles (17 and 18.8 %, respectively). Also the magnifying needs and mean age of the AMD patients did not change significantly between the two periods (2007-2011 versus 1999-2005). The detailed analysis for dry and neovascular AMD for the years 2010 and 2011 showed no significant differences for the most commonly prescribed low vision aids. The prescription of low vision aids is not influenced by the AMD classification (dry or neovascular), only by the magnification needs.

CONCLUSION

There is an unchanged and still high demand for rehabilitation aids of AMD patients, for dry as well as for neovascular AMD even after the introduction of anti-vascular endothelial growth factor (anti-VEGF) therapy.

[Ophthalmological rehabilitation of visually impaired children]

BACKGROUND

There are very few studies on visually impaired children in Germany; therefore, the aim of this study was to investigate the current spectrum of diseases of visually impaired children and the care of these children in schools and kindergartens with aids and integrative support.

PATIENTS AND METHODS

In a retrospective study all children (n =303) who attended the outpatient department for the visually impaired of the University Eye Hospital Tübingen in 2013 and 2014 were evaluated. The target values were ophthalmological diagnosis, best corrected visual acuity, needs for magnification, prescribed aids, measures for early support and integrative care and inclusion during schooltime.

RESULTS

The most frequent diagnosis in this collective which led to visual impairment in children was optic atrophy (22.4%) followed by hereditary retinal dystrophy (18.5%), congenital nystagmus (9.9%), albinism (8.6%), retinopathy of prematurity (ROP, 7.9%), aniridia (4.6%), cerebral visual impairment (CVI, 4.3%) and severe myopia (3%). Of the children 21% suffered from multiple disabilities, 66% were visually impaired (visual acuity ≤0.3 and >0.05), 9% were severely visually impaired (visual acuity ≤0.05) and 6% were legally defined as blind (visual acuity ≤0.02). Of the schoolchildren 52% (n = 241) were able to visit a mainstream school within the framework of integrative care. For 77% of these schoolchildren integrative care was already provided by a special pedagogic institution at the time of presentation for school entry and 73% of all the schoolchildren needed magnifying aids at school: 20% used optical magnifying aids (e.g. reading stones) and 53% needed electronic magnifying aids, such as screen magnifiers or camera reading systems.

CONCLUSION

Particularly for children, the use of magnifying aids for reading is essential for education in schools and 73% of the children used optical or electronic devices for reading. Of the children 52% attended a mainstream school and were additionally supported by special pedagogic counseling services.

[The influence of visual rehabilitation on secondary depressive disorders due to age-related macular degeneration. A randomized controlled pilot study]

BACKGROUND

Age-related macular degeneration (AMD) often leads to visual impairment, loss of reading ability, reduced quality of life and secondary depression. The present study examined if visual rehabilitation has a preventive effect on secondary depression in these patients.

MATERIAL AND METHODS

In a controlled pilot study 20 patients were randomized into 2 groups whereby 9 underwent visual rehabilitation at first examination and 11 received magnifying visual aids only after 3 months. Psychosocial status was assessed by the geriatric depression scale (GDS) and the German version of the Centre for Epidemiologic Studies depression (CES-D) scale (main outcome parameter), cognitive status by the dementia detection test (DemTecT), minimental status (MMS) and quality of life by the National Eye Institute visual function questionnaire (NEI-VFQ 25). Ophthalmological examination included reading speed measurement by standardized texts (International Reading Speed Texts; IReST).

RESULTS

Parameters of the CES-D scale, DemTect and the subitem exercise of social roles of the NEI-VFQ 25 emerged in a divergent manner. Patients of the rehabilitation group became less depressive and improved in cognitive and social abilities and in the control group vice versa. The interactive effect of group and time was statistically significant for all three tests.

CONCLUSIONS

Visual rehabilitation has a positive impact on depression as well as cognitive status and quality of life in patients with AMD. The effects have to be confirmed in future studies with more patients and a longer observation period.

Binding of platelet glycoprotein Ibbeta through the convex surface of leucine-rich repeats domain of glycoprotein IX

BACKGROUND

The mechanism of assembly of the platelet glycoprotein (GP) Ib-IX complex from GPIbalpha, GPIbbeta and GPIX subunits is not entirely clear. In this complex, ectodomains of both GPIbbeta and GPIX subunits contain two leucine-rich repeats (LRR) and share high sequence similarity. However, they differ noticeably in stability, hampering further analysis of their interaction.

OBJECTIVES AND METHODS

Guided by analysis of the LRR structure, we report a well-folded Ibbeta/IX chimera and its usage in dissecting GPIX function.

RESULTS

In this chimera, three non-contiguous sequences that may constitute the putative convex surface of the GPIbbeta ectodomain are replaced by their GPIX counterparts. Like GPIbbeta but unlike GPIX ectodomain, it can secrete from transfected Chinese hamster ovary cells and fold into a stable conformation. Furthermore, replacing the ectodomain in GPIX with the Ibbeta/IX chimera, but not the GPIbbeta ectodomain, preserved its interaction with GPIbbeta as demonstrated by its native-like GPIbbeta-induced increase in surface expression and coimmunoprecipitation.

CONCLUSIONS

The putative convex surface of the LRR domain in GPIX is sufficient, in the context of full-length subunit, to mediate its association with GPIbbeta.

Akkommodationsfähigkeit unter Einbeziehung refraktiver, biometrischer und demographischer Parameter

PURPOSE

The aim of this study was to evaluate the accommodation ability in healthy phakic eyes in relation to refraction and biometric parameters in order to get comparable results for patients with the accommodative 1 CU posterior chamber lens.

METHODS

The study included 120 normal eyes of 120 patients (77 males, 43 females, mean age: 40+/-18, range: 11-70 years). The inclusion criteria were spherical equivalent for distance refraction <2 D, astigmatism <1.5 D, and a best-corrected visual acuity > or =0.8. Exclusion criteria were diabetes, glaucoma, cataract, traumas, or previous surgery. Subjects were divided into six age groups at increments of 10 years. Each group consisted of 20 subjects. Measurements included subjective and objective refraction (D), the accommodation ability (D) assessed with an accommodometer, and biometric parameters using the IOLMaster. In addition, the relation of anterior chamber depth and length of the eye was calculated for analyzing the relationship of anterior eye segment and accommodation.

RESULTS

The spherical equivalent for distance refraction was 0.04+/-0.6 D with a range of -1.5 to 2.0 D. There was no sex-related significant difference of accommodation range. The accommodation range (D) decreased significantly with increasing age (p<0.0001, r=-0.895). The highest decrease could be found between the ages of 30 and 50 years. In subsequent years, the decline in accommodation ability was comparatively less. In association with the anterior chamber depth and the relation of anterior chamber depth and length of the eye, the accommodation ability fell with increasing age (p<0.001). The length of the eye did not correlate with the accommodation ability (p=0.8).

CONCLUSION

There is a strong relationship between accommodation ability and age. Accommodation ability decreases strongly from the 3rd to the 5th decade; after that the loss of accommodation ability is relatively lower. The increase in lens thickness during the life span can implicate a correlation between the change of anterior chamber depth in relation to the length of the eye and a decrease of accommodation ability. Our results confirm Duane's hypothesis of accommodation and age.

Klinik und Therapie der Immunreaktionen nach perforierender Normalrisiko-Keratoplastik

PURPOSE

Endothelial graft rejection is one of the most common causes of graft failure following penetrating keratoplasty (PK). The aim of this study was to evaluate the incidence, time course and outcome of treatment of graft rejection after normal-risk PK and to identify possible risk factors for the recurrence of immune reactions and irreversible graft failure.

PATIENTS AND METHODS

The study included 500 eyes from the prospective Erlanger Normal-risk Keratoplasty Study with a mean follow-up of 42 +/- 18 (median 40) months. Indications for PK were keratoconus in 48 %, Fuchs' dystrophy in 30 %, secondary bullous keratopathy in 11 %, non-vascularized corneal scars in 7 % and stromal dystrophies in 4 %. Standardized complete ophthalmological examinations were performed on a regular basis before, during the acute graft rejection and then regularly in a defined examination raster in an cornea out-patient service.

RESULTS

During follow-up 29 eyes (5.6 %) developed an episode of endothelial graft rejection (23 eyes with acute diffuse and 6 eyes with chronic focal rejection type). Episodes of endothelial graft rejection clustered between 11 and 25 months postoperatively (15 from 29, 51.7 %). Most grafts (25 of 29) regained clarity after topical and systemic steroid treatment. Only 4 patients showed an irreversible graft failure requiring a repeat PK, all of whom had secondary bullous keratopathy as the primary indication for PK. Risk factors for irreversible graft failure were pre-existing anterior synechiae in 3 patients and secondary open angle glaucoma in pseudoexfoliation syndrome in one patient. Recurrence of graft rejection was seen in 5 patients (all with keratoconus) after a time interval of 8 to 12 months. Under very low topical steroid treatment no further recurrence was observed in all 5 patients up to 2 years.

CONCLUSION

Patients should be followed-up on a regular base for longer postoperative periods, since most episodes of graft rejection were observed between 1 and 2 years after PK. Development of irreversible graft failure was strongly associated with pre-existing anterior synechiae and pre-existing glaucoma. Low-dose topical steroid treatment after immunological rejection seems to prevent the recurrence of further graft rejection.

[Functional outcomes after penetrating keratoplasty in pseudoexfoliation syndrome (PEX)-keratopathy]

PURPOSE

Keratopathy in pseudoexfoliation syndrome (PEX-keratopathy) is a particular form of corneal endothelial decompensation, which requires a penetrating keratoplasty (PK) for visual rehabilitation at advanced states. The aim of this study was to evaluate the functional outcome and the development of intraocular pressure (IOP) after PK in patients with PEX-keratopathy depending on the presence of pre-existing glaucoma.

PATIENTS AND METHODS

This retrospective study included 21 eyes of 21 patients (age 78.6 +/- 7.5 years) with a mean postoperative follow-up of 1.8 +/- 2.2 (median 2) years. The diagnosis of PEX-keratopathy was confirmed clinically as well as by electron microscopy. The recipient and donor trephinations were performed from the epithelial side using an 193 nm excimer laser (n = 11) or mechanically (n = 10). An iridotomy was performed routinely during PK. The postoperative treatment with topical steroid was standardized.

RESULTS

Preoperatively, a secondary open-angle glaucoma (SOAG) with optic nerve damage was diagnosed in 11 patients (52 %). Topical antiglaucomatous treatment was needed in 81 % of patients with SOAG. Six weeks postoperatively, patients with SOAG showed a higher prevalence of increased intraocular pressure (IOP) and/or antiglaucomatous treatment compared to patients without SOAG (45 % vs. 20 %). Most of the mild-early intraocular pressure elevations were controlled in both groups during the follow-up. From one year post-PK, there was an increased need for topical antiglaucomatous treatment in both patient groups. In all eyes the IOP was controlled by topical antiglaucomatous treatment. Preoperatively, visual acuity was comparable in patients with and without SOAG (0.06 +/- 0.09 vs. 0.08 +/- 0.1, p = 0.7), but increased significantly more in patients without SOAG (0.38 +/- 0.1, median 0.4) than in patients with SOAG (0.2 +/- 0.1, median 0.2; p = 0.01) after PK. Visual acuity remained stable in both groups throughout the follow-up period. During follow-up only one eye developed an episode of reversible endothelial graft rejection 18 months postoperatively. An irreversible graft failure was seen in none of the patients.

CONCLUSION

The functional outcome after PK in PEX-keratopathy seems to be strongly associated with pre-existing SOAG. Patients without SOAG may expect good visual rehabilitation without persistent postoperative IOP increases. However, patients should be followed-up for a prolonged period of time, because from 1 year following PK the need for topical antiglaucomatous treatment increased significantly.

[Results of the first 1,000 consecutive elective nonmechanical keratoplasties using the excimer laser. A prospective study over more than 12 years]

BACKGROUND AND PURPOSE

The purpose of this prospective clinical cross-sectional study was to analyse indications, intraoperative, perioperative and postoperative pecularities and complications as well as postoperative functional and morphologic results of the first 1000 consecutive elective round laser keratoplasties.

PATIENTS AND METHODS

The age of the 480 females and 520 males (362 x keratoconus), who had been operated on between 07/1989 and 04/2002 ranged from 20 to 92 years (mean 55+/-19). A total of 6 microsurgeons performed 718 x PK only, 222 x a triple procedure and 60 x additional IOL manoeuvres. Recipient and donor trephinations were accomplished with an 193 nm excimer laser (Carl Zeiss Meditec, Jena, Germany) from the epithelial side.

RESULTS

In 895 eyes with perioperative corneal erosion, epithelial healing took not more than 3 days in half of cases. During a follow-up period of 1.9+/-1.5 years, in 35 eyes episodes of acute diffuse (8 irreversible) and in 12 eyes episodes of chronic focal (5 irreversible) endothelial immunologic graft reactions (4.7%) occurred between 6 weeks and 4.7 years after PK. Before/after suture removal, median values of astigmatism were 1.5 diopters (D)/2.5 D refractive, 3.0 D/3.3 D keratometric, and 4.0 D/4.2 D topographic. Best-corrected visual acuity was 0.50/0.60, respectively.

CONCLUSIONS

More than 12 years of experience with this new technique indicate that besides optical advantages, nonmechanical trephination does not cause intraoperative or postoperative disadvantages for the patient. Under standardised surgical conditions a massive increase of astigmatism after suture removal seems to be avoidable with laser trephination in most cases due to reduction of decentration,"vertical tilt" and especially "horizontal torsion".

Digitale Planimetrie zur Langzeitverlaufskontrolle der glaukomat�sen Papillensch�den bei Patienten mit Normaldruckglaukom

BACKGROUND

Aim of the study was to evaluate the validity of quantitative planimetry of the optic disc with a new digital method and to assess the correlation of the measurements with morphological changes in eyes with low tension glaucoma.

MATERIAL AND METHODS

The study included 40 eyes from 40 patients (age 61+/-12 years) with low tension glaucoma with a mean follow-up of 4.9+/-2.1 (range 3-9) years. All patients underwent annually complete ophthalmological examination including 15 degrees color optic disc photographs and automated white-white visual fields.

RESULTS

Out of 40 eyes morphological examination showed signs of progression in 18 eyes and in 22 eyes no morphological changes of the optic disc were detected The digital planimetrically measured optic disc area did not vary between the first and the last photos. The mean differences between measured values for optic disc area between two examinations were 0.027+/-0.071 mm(2) and the reliability coefficient (Cronbachs alpha) was 0.99. Neuroretinal rim area decreased statistically highly significantly in eyes with morphological progression, and in eyes without morphological changes decreased only slightly.

CONCLUSIONS

The variation of measurements of the optic disc area can be minimized by consideration and adjustment of the individual image magnification of the photos using digital planimetry. This method allows the quantitative assessment even of slight changes of the neuroretinal rim area and is a useful examination for follow-up of glaucoma patients.

[Two years experience with the new accommodative 1 CU intraocular lens]

After marked improvement of optical rehabilitation of cataract patients during the last decades due to small incision surgery and foldable intraocular lenses (IOL), presbyopia is now one of the great unsolved questions in ophthalmology. During recent years a new accommodative IOL, the 1CU lens, has been developed based on the concepts of K.D. Hanna and on finite element computer simulation models. The 1CU IOL is designed to transform contracting forces of the ciliary muscle into anterior movement of the IOL optic (optic-shift concept). After the first implantation of a 1CU IOL in Erlangen in June 2000, we have now successfully implanted the 1CU IOL in over 90 patients. Our experiences and the results of several clinical studies indicate good and safe implantability, good centration, no IOL-specific complications, and good distance visual acuity. In comparison to control groups with conventional IOL, patients with the 1CU enjoyed significantly better distance-corrected near visual acuity, a larger accommodative range, and increased anterior and posterior axial movement of the lens optic after medical stimulation or inhibition of the ciliary muscle. We interpret our results as confirmation of the optic-shift concept of the 1CU IOL. Overall, the concept of accommodative IOL appears attractive and may have a great potential in the future. Additional studies including randomized blind multicenter evaluation of the 1CU IOL are necessary to further evaluate long-term and accommodative results.

Retinal nerve fiber layer measurements using laser scanning polarimetry in different stages of glaucomatous optic nerve damage

PURPOSE

To evaluate the diagnostic value of polarimetric measurements of the retinal nerve fiber layer (RNFL) thickness in different stages of glaucomatous optic nerve damage.

METHODS

The study included 92 eyes of 46 controls (age 41.0+/-13.7 years) and a heterogeneous group of 232 eyes of 135 patients with different stages of glaucomatous optic nerve damage (age 54.0+/-10.2 years; 68 patients with primary open-angle glaucoma, 56 with normal-pressure glaucoma and 11 patients with secondary glaucoma due to primary dispersion syndrome or pseudoexfoliation syndrome). All control subjects and patients underwent complete ophthalmological examinations including scanning laser polarimetry of the RNFL using the GDx (Laser Diagnostic Technologies, San Diego, Calif.) and 15 degrees color stereo optic disc photographs. Only subjects and patients with disc area less than 3.4 mm(2) were included in the study. The total glaucoma group were divided into four subgroups according to the morphological criteria of the neuroretinal rim.

RESULTS

The stage of morphological glaucomatous optic nerve damage was classified as follows: stage 0: n=92, stage 1: n=103, stage 2: n=65, stage 3: n=40, and stage 4: n=19. Differences in mean polarimetric retardation between controls and eyes with glaucoma were significant for all parameters except the variable symmetry. The most significant differences between controls and eyes with glaucomatous optic nerve damage were found with the "number" variable assigned by the neural network analysis ( P<0.001). With increasing stage of glaucomatous optic nerve damage, separation of the variable "the number" increased significantly. At a predetermined specificity of 90% the sensitivity of the groups with different stages of morphological glaucomatous optic nerve damage increased from 32% for stage 1 to 90% for stage 4.

CONCLUSION

Polarimetric measurement of the RNFL thickness is significantly associated with morphological glaucomatous optic nerve damage. The fast performance, easy handling, and low cost of RNFL polarimetry mean that it can be included in the routine examination of glaucoma patients. Further study and refinement of this technique are indicated to improve its usefulness in both clinical diagnosis and in population-based case identification.

Impact of increased intraocular pressure on long-term corneal endothelial cell density after penetrating keratoplasty

PURPOSE

Besides immunological graft rejection, persistently increased intraocular pressure (IOP) is among the most important causes for graft failure after penetrating keratoplasty (PK). The purpose of this study was to assess the longitudinal development of IOP after PK and to investigate possible correlations with corneal endothelial cell density.

METHODS

This longitudinal prospective study included 209 eyes after PK with a complete follow-up at 3 months, 6 months, before first suture removal (16 +/- 5 months) and after complete suture removal (21 +/- 5 months). At each examination, IOP was measured by Goldmann applanation tonometry. Endothelial cell density was assessed by specular microscopy (EM 1100, Tomey). The indications for PK were 48% keratoconus, 34% Fuchs' dystrophy, 5.4% stromal dystrophies, 8.6% secondary bullous keratopathy and 4% corneal scars. An iridotomy was performed routinely during PK. The postoperative treatment with topical steroids was standardized.

RESULTS

Preoperatively, the mean IOP was 13.6 +/- 2.9 mm Hg with increased IOP (>21 mm Hg) in 2.0% of eyes. After 3 months, the incidence of increased IOP (24.5 +/- 4.6 mm Hg) was highest (6.7%) and decreased thereafter to 3.0% after complete suture removal. No patients showed IOP higher than 30 mm Hg. A persistently increased IOP for more than 3 months was seen in 2% of patients. At 3 months postoperatively, the mean endothelial cell density was 1,977 +/- 496/mm(2) and did not decrease significantly (p > 0.05) until 6 months (1,771 +/- 507 cells/mm(2)). At the end of the follow-up period, the mean endothelial cell density was significantly reduced (1,347 +/- 501 cells/mm(2)). There was no significant correlation between IOP and mean endothelial cell density at any postoperative examination stage (p > 0.24). Patients with persistently increased IOP for more than 3 months did not have significantly different endothelial cell densities in comparison with those without increased IOP.

CONCLUSION

From 6 months after PK, the incidence of increased IOP was not higher than the preoperative level. Mild to moderate temporary IOP elevations after PK do not seem to affect the endothelial cell density of the graft until complete suture removal. Further long-term studies are necessary to assess the clinical relevance of these observations.

[Conventional versus digital planimetry of optic disc photograph: a clinical comparative study]

BACKGROUND

The optic disc size is an important parameter for the diagnosis of glaucomatous and non-glaucomatous optic nerve damage. The aim of this study was to compare quantitative measurements of the optic disc with the established conventional planimetry and a new digital method using Soft imaging system analySIS(tm) for Ophthalmology and to determine the reproducibility of this new method.

PATIENTS AND METHODS

Fifty color stereo optic disc photographs of 50 patients (mean age 41.7 +/- 13.4 y) were included in the retrospective, comparative study. Conventional and digital planimetry was taken from one skilled examiner in a masked fashion. According to patient's number measurement values obtained with both methods were matched. Digital planimetric measurements of 10 optic disc photographs were repeated on day 7 and day 14. Statistical analysis was done using linear regression analysis, reliability coefficient and U-test.

RESULTS

The planimetric values did not vary significantly between the two methods for optic disc area (3.19 +/- 0.65 mm(2) vs. 3.03 +/- 0.64 mm(2), p=0.96), for cup area (1.36 +/- 0.62 mm(2) vs. 1.21 +/- 0.63 mm(2), p=0.96) or for neuroretinal rim area (1.83 +/- 0.39 vs. 1.82 +/- 0.41 mm(2), p=0.98). There was also no significant difference of horizontal and vertical diameter of optic disc and cup as well as the diameter of the superior temporal and inferior temporal retinal artery and vein at the optic disc border between both methods (p < 0.5). Differences between measured values for optic disc, optic cup area and neuroretinal rim area obtained with both methods were 0.16 +/- 0.10 mm(2) (range - 0.05 to 0.24), 0.15 +/- 0.10 mm(2) (range - 0.12 to 0.26) and 0.014 +/- 0.11 mm(2) (range - 0.26 to 0.26). A high correlation of all planimetric values was observed between both methods (r=0.9, p < 0.0001). Using digital planimetry differences between day 1, day 7 and day 14 were 0.05 +/- 0.03 (range 0.02 to 0.10 mm(2)) for optic disc, 0.05 +/- 0.04 (range 0.0 to 0.13 mm(2)) for optic cup area and 0.05 +/- 0.05 (range 0.01 to 0.14 mm(2)) for the neuroretinal rim area. The reliability coefficient of digital planimetry was 0.9 for optic disc parameters.

CONCLUSIONS

The comparable results between both methods and a high reproducibility suggest that the digital planimetry could be used either for clinical routine or scientific evaluation of the optic nerve.

Blood-aqueous barrier breakdown after penetrating keratoplasty with simultaneous extracapsular cataract extraction and posterior chamber lens implantation

BACKGROUND

The purpose of this study was to quantify breakdown of the blood-aqueous barrier (BAB) following penetrating keratoplasty (PK) with simultaneous extracapsular cataract extraction and posterior chamber lens implantation (triple procedure) and compare it with the alterations following PK only.

METHODS

This study included 72 eyes after triple procedure and 227 eyes after PK only. The diagnosis for PK was Fuchs dystrophy in 39%, keratokonus in 44%, stromal corneal dystrophy in 3% and avascular corneal scars in 6% of cases. The postoperative topical steroid treatment was standardized in both groups. Aqueous flare was quantified using the laser flare-cell meter (FC-1000, Kowa) at defined postoperative intervals (10 days, 6 weeks, then every 3 months until 1 year postoperatively). Patients with conditions associated with impairment of the BAB were excluded from the study.

RESULTS

In the early postoperative course, aqueous flare values (photon counts/ms) were significantly higher in patients with triple procedure (21.9 +/- 11.0) than in patients with PK only (9.8 +/- 3.2; P = 0.001). At 6 weeks postoperatively, aqueous flare returned to normal levels in patients after PK only (5.2 +/- 2.3), whereas patients with triple procedure still showed significantly increased flare values (10.8 +/- 5.6; P = 0.01). At 6 months postoperatively, aqueous flare values of patients with triple had returned to normal levels (6.8 +/- 3.8) and did not differ significantly from those after PK only (5.2 +/- 1.9; P = 0.09).

CONCLUSION

Our results indicate that triple procedure causes a more extensive and longer-lasting breakdown of the blood-aqueous barrier than PK only. Quantification of aqueous flare with the laser flare-cell meter is useful in the postoperative follow-up after triple procedure. Further studies are required to investigate the clinical relevance of BAB breakdown on endothelial cell count and the incidence of subsequent immunological graft rejection.

Effect of neodymium:YAG laser iridotomy on number of aqueous melanin granules in primary pigment dispersion syndrome

PURPOSE

Increased numbers of aqueous melanin granules have been reproducibly demonstrated in eyes with pigment dispersion syndrome using the cell count mode of the laser flare-cell meter. It was the aim of this study to measure the exact number of aqueous melanin granules in eyes with pigment dispersion syndrome and pigmentary glaucoma before and after Nd:YAG laser iridotomy.

METHODS

Nine eyes of seven patients with a clinical diagnosis of primary pigment dispersion syndrome and secondary open-angle glaucoma (mean age 41.1 +/- 10.8 years) were included in this study. Aqueous cells were quantified using the cell count mode of the laser flare-cell meter (Kowa FC-1000) before and 30 min after medical pupillary dilation. Measurements were performed before and 15 +/- 7 weeks after Nd:YAG laser iridotomy. The main outcome measure was the number of aqueous melanin granules before and after Nd:YAG laser iridotomy.

RESULTS

The number (mean and quartiles) of aqueous melanin granules/0.075 microl aqueous humor (normal/dilated pupil) before antiglaucoma treatment was 4.5 (4.0, 7.25)/ 9.0 (5.0, 13.0) and was significantly reduced after iridotomy [1.5 (0.75, 3.25)/4.0 (1.6, 6.25), P=0.016].

CONCLUSION

Nd:YAG laser iridotomy results in significant (65%) decrease of aqueous melanin granules in eyes with primary pigment dispersion syndrome. This finding appears to confirm the concept of reverse pupillary block in primary pigment dispersion syndrome and may indicate that laser iridotomy is a useful treatment option in this condition.

Impact of short-term versus long-term topical steroids on corneal neovascularization after non-high-risk keratoplasty

PURPOSE

To analyze incidence and extent of corneal neovascularization (CN) after non-high-risk keratoplasty and to find out whether duration of postoperative topical steroid therapy (6 vs 12 months) affects CN, corneal endothelial cell count, pachymetry, aqueous flare values, and best-corrected visual acuity at 1 year after keratoplasty.

METHODS

Patients of the prospective Erlangen non-high-risk keratoplasty study with available high-quality corneal photographs taken preoperatively and 1 year later were analyzed (n=136). Corneal photographs were evaluated by two independent observers in a standardized semiquantitative fashion. Slides were projected with 100x magnification and corneal vessels classified into five grades with regard to the limbus, sutures and host-graft junction in each of 12 corneal sectors. Incidence and extent of CN after keratoplasty and relation to short-term (0-6 months) versus long-term (0-12 months) postoperative topical steroid therapy were analyzed. The effect of duration of topical steroid therapy on corneal endothelial cell count, pachymetry, aqueous flare values, and best corrected visual acuity was also analyzed. Of the 136 patients, 69 (51%) were randomly assigned to short-term and 67 to long-term topical prednisolone acetate 1%.

RESULTS

Fifty-eight percent of patients (n=79) developed a CN within 1 year after keratoplasty in at least one corneal sector (mean 3.1 +/- 2.2, range 1-10). At 1 year after keratoplasty, only in 12% of these patients did at least one vessel reach the host-graft junction or grow into the donor cornea, whereas in 51% vessels were seen beyond the outer suture ends of the double running suture without reaching the host-graft junction. In 37%, capillaries were located between limbus and outer suture ends. New vessels usually pointed directly or indirectly to the outer suture ends and usually were located around the 12 o'clock and 6 o'clock positions. There was no significant difference regarding incidence and extent of CN 1 year after keratoplasty between the long-term and the short-term group. Duration of topical steroid therapy had no significant effect on corneal endothelial cell count and thickness, aqueous flare values and best-corrected visual acuity at 6 and 12 months postoperatively (only at 12 months, corneas in the long-term treatment group were slightly thicker; P=0.03). Interobserver correlation of vessel assessment was 0.77 (Kendall's tau B).

CONCLUSIONS

CN is a common phenomenon after non-high-risk keratoplasty. New vessels rarely reach the host-graft junction, most commonly develop from the 6 o'clock and 12 o'clock positions and are usually located between epithelium and Bowman's layer (i.e., at the level of the superficial suture). The direction of vessel growth from the limbus towards the outer suture ends suggests release of angiogenic factors in this area. Prolongation of topical steroid therapy after non-high-risk keratoplasty beyond 6 months in this study did not significantly influence incidence and extent of CN, corneal endothelial cell count, aqueous flare values and best-corrected visual acuity observed 1 year after keratoplasty.

[Visual rehabilitation and intraocular pressure elevation due to immunological graft rejection following penetrating keratoplasty]

PURPOSE

Endothelial graft rejection and intraocular pressure elevation are the most common causes of graft failure following penetrating keratoplasty (PK). Aim of this study was to evaluate the visual rehabilitation and the development of intraocular pressure during and after graft rejection.

PATIENTS AND METHODS

The study included 20 eyes of 20 patients (age 54.7 +/- 19.8 years) with endothelial graft rejection, that fulfilled the following inclusion criteria 1) graft rejection was diagnosed and treated in our department; 2) at least one year follow-up after graft rejection; 3) avascular corneal pathology. The mean follow-up was 23 +/- 14 months. According to the type of surgical procedure patients were classified in PK only (n = 15, one after cataract extraction), PK combined with extracapsular cataract extraction and intraocular lens (IOL) implantation (n = 1); PK combined with secondary IOL-implantation or IOL-exchange (n = 4). Standardized complete ophthalmological examinations were performed on a regular basis before, during the acute graft rejection und then regularly in a defined examination raster in an out-patient service with cornea specialization.

RESULTS

The time interval between first symptom of 18 acute diffuse and 2 chronic focal graft rejection and start of treatment was 9 +/- 13 days. Best-corrected visual acuity (CVA) was 0.6 +/- 0.2 before graft rejection and decreased significantly at the time of diagnosis (0.2 +/- 0.2; p = 0.001). Six weeks after graft rejection CVA was 0.5 +/- 0.2 and remained almost stable until one year after rejection (0.6 +/- 0.3) in 16 patients with reversible graft rejection. Only 4 patients (20%) showed an irreversible graft failure requiring Re-PK. Intraocular pressure (IOP) was not elevated in 75% of the patients (n = 15) and did not need any antiglaucomatous treatment during and after the rejection phase. In 5 eyes (25%) (3 after PK combined with anterior chamber IOL-explantation and secondary posterior chamber IOL-implantation; 1 with secondary pseudoexfoliation glaucoma and 1 steroidal responder) IOP was elevated during graft rejection (26 +/- 7 mmHg), but was controlled by intensive topical antiglaucomatous treatment.

CONCLUSION

Typically, the visual rehabilitation after graft rejection was good if the clinical signs were diagnosed just in time and treated adequately. There is no direct correlation between graft rejection and intraocular pressure elevation. However, the development of intraocular pressure elevation seems to be strongly associated with preexisting glaucoma, preexisting anterior synechiae and/or simultaneous anterior chamber lens implant removal. A careful patient management after PK plays an important role to prevent the development of irreversible graft failure due to graft rejection.

Graft endothelium and thickness after penetrating keratoplasty, comparing mechanical and excimer laser trephination: a prospective randomised study

PURPOSE

To assess the impact of nonmechanical trephination on the graft endothelium and thickness after penetrating keratoplasty (PK).

METHODS

Inclusion criteria for this prospective, randomised, cross-sectional, clinical study were: (1) Treatment between October 1992 and December 1997; (2) one surgeon (G.O.H.N.); (3) primary central PK; (4) Fuchs' dystrophy (diameter 7.5/7.6 mm) or keratoconus (diameter 8.0/8.1 mm); (5) graft oversize 0.1 mm; (6) no previous intraocular surgery; (7) 16-bite double-running diagonal suture. In 179 patients (mean age 51+/-18 years), PK was performed using either the 193-nm Meditec MEL60 excimer laser ("Excimer") along metal masks with eight "orientation teeth/notches" (53 keratoconus, 35 Fuchs' dystrophy) or motor trephination with the Mikrokeratron (Geuder) ("Control": 53 keratoconus, 38 Fuchs' dystrophy). For donor trephination from the epithelial side an artificial anterior chamber was used in both groups. In 27% of the excimer and 29% of the control group a triple procedure was performed. Specular microscopy (EM-1000, Tomey) and pachymetry (SP-2000, Tomey) were performed before removal of the first suture (0.4+/-0.2 years postoperatively), before (1.1+/-0.4 years) and after (1.7+/-0.6 years) removal of the second suture but before any additional surgical intervention.

RESULTS

Endothelial cell count: Neither "two-sutures-in" (1953+/-426/1804+/-385 cells/mm2, p=0.13), "one-suture-in" (1629+/-439/1765+/-440 cells/mm2, p=0.27), nor "all-sutures-out" (1259+/-493/1294+/-532 cells/mm2, p=0.83) differed significantly between Excimer and Control. Graft thickness: Neither "two-sutures-in" (527+/-58/524+/-16 mucrom, p=0.89), "one-suture-in" (537+/-72/551+/-40 microm, p=0.86), nor "all-sutures-out" (576+/-53/565+/-62 microm, p=0.38) differed significantly between Excimer and Control. Cell count and corneal thickness were not significantly different comparing Fuchs' dystrophy and keratoconus or comparing PK only and triple procedures. Graft thickness and endothelial cell count correlated highly significantly inversely with "all sutures out" (P<0.0001).

CONCLUSIONS

Excimer laser trephination from the epithelial side using an artificial anterior chamber in donors seems to have no disadvantages concerning the graft endothelium after PK. Endothelial cell loss was not increased in eyes with Fuchs' dystrophy compared with keratoconus or after triple procedures compared with PK only.

[Modeling corneal topography with a subdivision scheme in keratoconus]

BACKGROUND

Videokeratoscopy is often unable to obtain complete data sets in cases of irregular or asymmetric corneal topography. Subdivision schemes are very common in computer graphics for completion and smoothing of surfaces. Based on a network of triangular facets a smooth and complete surface in a standard coordinate system can be derived from topographic raw data.

PATIENTS AND METHODS

We examined 88 patients with keratoconus and 40 normal controls. Polygons and polyhedra were defined from videokeratoscopic height data, and a surface was modeled using a modified butterfly subdivision scheme for a nonuniform sampled grid. To assess the model quality topographic raw data were changed to missing values centrally (at the apex of the cone) and in four midperipheral quadrants. The target value was the root mean square error, comparing the remodeled value of the subdivision scheme to the raw data at the position of the missing values for each group.

RESULTS

Due to the nonuniform mesh of our Placido-based topographer we used a dynamic adaptive model and the governing dynamic differential equation. With a single missing value, no difference was detected between normals and patients with keratoconus. For a missing area consisting of 13 raw data points, the remodeling error was significantly higher in patients with keratoconus than in normals. With the neighborhood of 13 missing data points, the apex of the cone was remodeled in both groups of patients with less precision than with the peripheral missing data.

CONCLUSION

The locality of the equation systems to be solved and the easy calculation of explicit formulas for the normals may simplify ray-tracing techniques and make subdivision attractive for large datasets in corneal topography even with irregular patterns.

[Laser tyndallometry and monitoring of treatment in 20 children with juvenile uveitis]

BACKGROUND

Treatment of children with juvenile uveitis requires adequate control of inflammation while minimizing systemic or ocular side effects. The study was performed to evaluate the potential use of the laser flare-cell meter in monitoring and adjustment of therapy in juvenile uveitis.

PATIENTS AND METHODS

Retrospectively, we monitored 20 children (11 girls and 9 boys) with an age range from 3 to 15 years presenting with juvenile iridocyclitis (10/20), intermediate (5/20) or posterior (5/20) uveitis. During the follow-up period (median 25.2 months, range: 2 to 83 months) multiple clinical controls were performed. We recorded clinical data, present therapy, and measurements using the laser flare-cell meter (Kowa FC-1000).

RESULTS

Laser flare-cell meter measurements were easily obtained and highly reliable even in these young patients. During follow-up, 36 recurrences of intraocular inflammation were detected in 19 eyes. Relapses of inflammation as well as a response to treatment were seen at an early stage. Semiquantitative observations of cells and aqueous flare in the anterior chamber, or visual acuity of patients were less reliable in predicting recurrences.

CONCLUSIONS

Laser tyndallometry offers a reliable, examiner-independent method to assess intraocular inflammation in children with juvenile uveitis and to adjust the necessary treatment.

[Blood-aqueous barrier after phacoemulsification with posterior chamber lens implantation; foldable acrylate lens vs PMMA lens-- a clinical study on 46 eyes]

BACKGROUND

Cataract surgery leads to a more or less pronounced postoperative inflammation due to breakdown of the blood-aqueous barrier. This alteration of the blood-aqueous barrier can be reduced by minimally invasive surgery. The purpose of this study was to quantify the early course of the postoperative alteration of the blood-aqueous barrier following phacoemulsification with implantation of conventional PMMA posterior chamber lens (IOL) in comparison with foldable acrylic lens implantation.

PATIENTS AND METHODS

Forty-six eyes of 46 patients (age 63 +/- 8.8 years) without preexisting deficiences of the blood-aqueous-barrier or previous intraocular surgeries were divided into two groups: group 1 (24 patients): phacoemulsification with one-piece-PMMA-IOL implantation (6.5 mm corneoscleral tunnel incision); group 2 (22 patients): phacoemulsification with foldable acrylic-IOL implantation (3.5 mm incision, 15 patients with corneoscleral tunnel and 7 patients with clear cornea incision). All surgical procedures were performed by one surgeon. The postoperative treatment was standardized. Alteration of the blood-aqueous barrier was quantified by the laser flare-cell meter (Kowa, FC-1000) preoperatively and on the first and the second day after surgery.

RESULTS

Preoperative aqueous flare values (photon counts/ms) were comparable in both groups (6.7 +/- 2.7 versus 5.6 +/- 2.7 respectively, p = 0.1). On day 1, aqueous flare in group 1 (9.7 +/- 2.9) was not statistically significantly higher than in group 2 (9.2 +/- 2.2, p = 0.2) and remained relatively constant on day 2 after surgery (9.3 +/- 3.3), whereas the aqueous flare values in group 2 decreased statistically significant (6.7 +/- 2.3, p = 0.01). Postoperatively, there was no statistically significant difference of aqueous flare values between eyes with corneoscleral tunnel incision and eyes with clear corneal incision (p = 0.7) in group 2.

CONCLUSIONS

Our study shows that phacoemulsification with foldable IOL implantation leads to a mild and short-lasting alteration of the blood-aqueous barrier. Thus, implantation of foldable IOL may be useful in eyes especially with preexisting alteration of the blood-aqueous-barrier.

[Interim results from the prospective "Erlanger Non-high-risk Penetrating Keratoplasty Study" in 207 patients]

BACKGROUND

Immunologic graft rejection targeted against corneal endothelium is the most frequent cause for graft failure after corneal transplantation. The purpose of this prospective study was to assess the frequency, early symptoms, prophylaxis and therapy monitoring of corneal graft rejection following non-high-risk penetrating keratoplasty (PK).

PATIENTS AND METHODS

From February 1997 to May 1999, 237 patients undergoing non-high-risk PK have been enrolled in this prospective study. We evaluated 207 patients (103 female, 113 right eyes, recipient age 54 +/- 20 years, donor age 59 +/- 17 years). In 2 randomized treatment studies we compared the efficacy of postoperative short-term (ST = 6 months) versus long-term (LT = 12 months) topical steroid therapy on the incidence of graft rejection and the effect of high- versus low-dose systemic steroid therapy on the prognosis after a graft rejection. Follow-up examinations included, laser-tyndallometry, corneal topography analysis, endothelial cell count and pachymetry.

RESULTS

The main indications for PK were keratoconus (n = 93), endothelial dystrophy Fuchs (n = 52) and bullous keratopathy (n = 35). In 151 (73%) patients, non mechanical trephination with the 193 nm Excimer laser was performed. Up to now, 78 patients were randomized into two groups comparing the postoperative therapy with topical steroids. During follow-up (median: ST: 13.5 months; LT: 12.5 months, maximum 25.3 months) episodes of endothelial graft rejection (3 chronic focal, 8 acute diffuse) showed 11 eyes of 11 patients. Five patients each had short-term and long-term topical steroid treatment. In 1 patient the graft rejection occurred before randomization at 6 months. Six patients with graft rejection episodes underwent a PK only (54% of graft rejections, 4.4% of all patients). In the remaining 5 patients, PK was combined with a lens surgery (46% of graft rejections, 6.9% of all patients). Ten of 11 corneal grafts regained their full function under treatment with systemic and local steroids.

CONCLUSION

The frequency of episodes of graft rejection in our study was lower than usually reported in the literature. A good compliance of patients appears to be a major factor for improved prognosis of the graft after PK and in case of graft rejection. Until now no significant differences between short-term or long-term postoperative topical steroid therapy could be detected regarding the incidence of corneal graft rejection.

[Analysis of the blood aqueous barrier by measurement of aqueous flare in 31 eyes with Fuchs' heterochromic uveitis with and without secondary open-angle glaucoma]

BACKGROUND

Fuchs' heterochromic uveitis is characterized by low-grade intraocular inflammation and a relatively benign clinical course. It was the aim of this study to quantitatively determine alterations of the blood-aqueous barrier in this disease by measuring the aqueous flare.

METHODS

31 affected eyes of 31 patients with the characteristic clinical picture of Fuchs' heterochromic uveitis, 31 apparently unaffected contralateral eyes, and 120 age and sex-matched normal control eyes were included in this retrospective study. Five of the eyes with Fuchs' heterochromic uveitis showed signs of secondary open-angle glaucoma. Determination of aqueous flare was performed in all eyes using the laser flare-cell meter FC-1000 (Kowa, Japan) after pupillary dilation.

RESULTS

Aqueous flare values were moderately but significantly increased in eyes with Fuchs' heterochromic uveitis (mean 12.1 +/- 3.6 photon counts/ms) in comparison to normal control eyes (4.1 +/- 1.3 photon counts/ms, p < 0.001). Flare values of apparently unaffected contralateral eyes (mean 3.9 +/- 1.1 photon counts/ms) did not differ from normal control eyes (p = 0.5). In the group of eyes with Fuchs' heterochromic uveitis, aqueous flare was comparable in eyes with and without secondary open angle glaucoma (11.9 +/- 2.5 versus 12.1 +/- 3.8 photon counts/ms, p = 0.9).

CONCLUSION

The alteration of the blood-aqueous barrier in patients with Fuchs' heterochromic uveitis is unilateral and relatively mild, corresponding to the well-known clinical picture of the disease. Secondary open-angle glaucoma appears not to be associated with additional increase of aqueous flare. The unilaterality and the relatively homogeneous distribution of the degree of increased aqueous flare values support the clinical impression that Fuchs' heterochromic uveitis is a distinct clinical entity that should be differentiated from other variants of chronic anterior uveitis.

Tumor growth of a choroidal malignant melanoma and aqueous flare. Report of a case

We report the use of the laser flare-cell meter (LFCM) in monitoring blood-ocular barrier breakdown induced by a choroidal malignant melanoma in an 88-year-old white male, who refused enucleation or radiation treatment. During a follow-up of 16 months, aqueous flare values measured with the LFCM increased from 12.8 to 26.5 photon counts/ms with continuous tumor growth from a height of 7.9 to 18 mm. Our finding of increasing flare values with tumor growth appears to confirm the observation that aqueous flare is influenced by the size of uveal malignant melanomas. Quantification of aqueous flare with the LFCM may be helpful in the follow-up of eyes with intraocular tumors.

Correlation among refractive, keratometric and topographic astigmatism after myopic photorefractive keratectomy

BACKGROUND

Photorefrative keratectomy can be used to flatten the curvature of the anterior cornea and reduce the myopic refraction of the eye. This leads to unphysiological topographical changes of the cornea and may alter the conditions for examinations of corneal surface topography. The purpose of this study was to check for mutual agreement of three different methods of assessment of astigmatism before and after myopic photorefractive keratectomy (PRK).

PATIENTS AND METHODS

Forty-seven eyes of 28 patients (age 32.7+/-6.6 years) following PRK using an 193-nm excimer laser were included in this study. 37 eyes were treated for pure myopia (-4.9+/-2.4 D) and 10 eyes for myopic astigmatism (sphere -2.0 to -7.0 D, cylinder -1.0 to -3.0 D). Preoperatively and at 18 months postoperatively, subjective refractometry, keratometry and topography analysis were performed. The axes of topographic and keratometric cylinder were standardized periodically (180 degrees) with respect to the refractive cylinder axis.

RESULTS

Pre- and postoperatively, the absolute astigmatism values correlated highly significantly between all three methods (P< or =0.001). The mean refractive cylinder was 0.65+/-0.61 D preoperatively and 0.46+/-0.41 D postoperatively (P=0.2). The mean keratometric astigmatism was 1.14+/-0.64 D before and 0.94+/-0.50 D after PRK treatment (P=0.2). Among the three methods, the mean topographic astigmatism was the highest (P<0.001) preoperatively (1.31+/-0.56 D) and postoperatively (1.21+/-0.52 D) (P=0.3). In eyes treated for pure myopia, no difference between pre- and postoperative refractive, keratometric and topographic astigmatism was detected (P>0.5). The axes of both topographic and keratometric astigmatism correlated highly significantly with the refractive cylinder axis (R> or =30.9, P<0.0001).

CONCLUSION

Up to 2 years after myopic PRK, the difference between refractive and keratometric astigmatism does not differ from the preoperative value, indicating an even corneal surface. The absolute astigmatism values and the cylinder axis correlated well between subjective and objective methods of astigmatism assessment. Thus, objective measurements may be helpful in determining the cylinder component of best spectacle correction after PRK. However, topographic analysis overestimates astigmatism values systematically before and after PRK.

[Frequency and risk factors of intraocular pressure increase after penetrating keratoplasty]

PURPOSE

The aim of this study was to evaluate the incidence, risk factors and management of glaucoma following penetrating keratoplasty (PK) and to check for possible correlations with the indication for PK.

PATIENTS AND METHODS

534 eyes of 483 patients (age 54.7 +/- 19.8 years), that had undergone PK from 1989 to 1999 were retrospectively analyzed. The mean follow-up was 2.7 +/- 1.8 years. According to the type of surgical procedure patients were classified in 5 groups: group 1) PK only (n = 291); group 2) PK combined with extracapsular cataract extraction and intraocular lens (IOL) implantation (n = 124); group 3) PK combined with secundary IOL-implantation or IOL-change (n = 32); group 4) PK only after previous cataract surgery (n = 55) and group 5) Cataract surgery after PK (n = 32). The trephination was performed from the epithelial side in donor and recipient either by nonmechanical trephination with the 193 nm excimer laser (n = 444) or mechanical trephination (n = 90). An iridotomy was performed routinely during PK. The postoperative treatment with topical steroids was standardized.

RESULTS

Preoperatively, glaucoma was diagnosed in 3.2% for all patients with groups 3 und 4 showing a significantly larger number of glaucomatous eyes (15.6% and 18.9%). Most of the mild early intraocular pressure elevations in group 1 (3.4%) and group 2 (3.0%) were controlled after 6 months (0.5% and 1.1%). Groups 3 and 4 showed most frequently increased intraocular pressure and/or antiglaucomatous treatment (21.4% and 18.7%) six weeks postoperatively. Patients in all groups showed no higher prevalence of persistent glaucoma from six months postoperatively than preoperatively throughout the follow-up period. Again groups 3 and 4 presented the largest number of persistent glaucoma. In most eyes the IOP was controlled by topical antiglaucomatous treatment. Serious forms seen in 2 patients with anterior synechiae caused by anterior chamber lens required several filtering surgeries or pars plicata diathermy, respectively. One patient with pseudoexfoliation syndrome required laser trabeculoplasty. The so-called "Urrets-Zavalia syndrome" was seen in none of the patients.

CONCLUSION

The development of increased intraocular pressure after PK varied with the indication for keratoplasty. Postkeratoplasty glaucoma seems to be strongly associated with preexisting anterior synechiae and/or simultaneous anterior chamber lens implant removal. Intraoperative iridotomy can prevent the development of acute angle closure glaucoma after keratoplasty.

[Regression analysis of corneal endothelium after nonmechanical penetrating keratoplasty]

PURPOSE

The corneal endothelial cell density is a crucial parameter for the pump function and the transparency of grafts after penetrating keratoplasty (PK). The purpose of this study was to assess corneal endothelial cell density with different regression models after nonmechanical penetrating keratoplasty and to check for differences between diagnoses and two different storage methods.

PATIENTS AND METHODS

Two-hundred ninety-six eyes (195 keratoconus, 101 Fuchs' dystrophies, 148 each with short-term preserved and organ-cultured donor corneas) of 268 patients were included in this prospective study. Donor and recipient trephination was performed using nonmechanical trephination technique with the excimer laser 193 nm along metal aperture masks from the epithelial side. The time course of the endothelial cell density (specular microscope EM 1100, TOMEY, Erlangen) after PK was assessed. Endothelial cell density was first analyzed in a cross sectional manner at the 3, 6, 12, 18 and 24 months follow-up and, secondly in a longitudinal manner with linear, polynomial and exponential regression models in the sense of minimizing the residuum (distance between observed and predicted endothelial cell count). The mean donor postmortem time was 10.3 +/- 6.8 hours for short-term-preserved and 19.6 +/- 9.5 hours for organ-cultured corneas (p < 0.0001). The storage time was 63 +/- 49 and 19 +/- 7 days (p < 0.0001), respectively.

RESULTS

In a cross section, overall mean endothelial cell density decreased from 2145 +/- 599 cells/mm2 at the 3 months to 1751 +/- 605 cells/mm2 at 2 years follow-up (p > 0.05). Cell density did not differ significantly between different diagnoses or storage methods at any postoperative stage. In a longitudinal section, the linear regression model estimated an annual decrease of 214 cells/mm2. In a polynomial model the decrease expressed by a tangent to the regression line at 24 months was 175 cells/mm2. The exponential regression model yielded a relative decrease of 9.5% annually. The so-called residuum as a measure for the validity of the regression model was maximal in the linear and minimal in the exponential estimate. With keratoconus and short-term preserved donor material the endothelial cell loss was less in the regression analysis.

CONCLUSION

During the first two years after nonmechanical trephination in PK, a non-significant decrease in endothelial cell density was observed. The exponential regression model seems to be predestinated for analysis of the time course of corneal endothelium in a longitudinal manner. The annual cell loss ranged around 9.5% without significant differences between diagnoses and storage methods.

Quantification of aqueous melanin granules, intraocular pressure and glaucomatous damage in primary pigment dispersion syndrome

OBJECTIVE

Aqueous melanin granules may be accurately quantified with the laser flare-cell meter and have been demonstrated to be increased in primary pigment dispersion syndrome (PDS). It was the aim of this study to correlate intraocular pressure, glaucomatous damage of the optic nerve head, and visual field defects with the number of aqueous melanin granules in PDS.

DESIGN

Cross-sectional study.

PARTICIPANTS

Thirty-nine eyes of 21 patients with PDS and either ocular hypertension or pigmentary glaucoma.

MAIN OUTCOME MEASURES

A 24-hour intraocular pressure (IOP) profile, automated perimetry (Octopus G1), and analysis of photostereographs and HRT (Heidelberg Retina Tomograph) images of the optic disc were performed. Aqueous melanin granules were quantified using the cell count mode of the laser flare-cell meter (KOWA FC-1000) with undilated and dilated pupils. Granule counts were correlated with maximum and mean IOP, maximum range (amplitude) of IOP, mean defect of automated perimetry (G1-program), and damage to the optic disc was measured with the HRT.

RESULTS

The number of aqueous melanin granules showed a strong correlation with maximum IOP in both undilated (r = 0.72, P < 0.001) and dilated eyes (r = 0.5, P = 0.02). A marginal correlation was found with the IOP range (r = 0.43, P = 0.04) and the mean defect of automated perimetry (r = 0.41, P = 0.06) in undilated eyes. The mean IOP and HRT measurements of the optic disc (area, volume of the neuroretinal rim, third moment in contour) showed no statistically significant correlation with the number of aqueous melanin granules (r < 0.4, P > 0.2).

CONCLUSIONS

A larger number of aqueous melanin granules is strongly associated with high IOP and also with visual field loss, providing additional evidence of the relation between aqueous melanin dispersion and development of pigmentary glaucoma. Quantification of aqueous melanin granules with the laser flare-cell meter might be useful for evaluation of treatment effects, including laser iridotomy, in patients with PDS.

[Development of visual acuity in the early phase after photorefractive keratectomy in myopia]

BACKGROUND

Photorefractive keratectomy (PRK) using the excimer laser is an accepted surgical technique for correction of myopic refraction errors in case of spectacle or contact lens incompatibility. The purpose of this study was to assess the development of uncorrected (UVA) and best-corrected visual acuity (CVA) in the early course following PRK.

PATIENTS AND METHODS

48 eyes of 29 patients that underwent myopic photorefractive keratectomy using 193 nm excimer laser (MEL 60, Aesculap-Meditec) were included in this study. The mean preoperative spherical equivalent was -5.3 +/- 2.4 diopters (D) (range -1.75 to -9.5 D). Pre-, intra- and postoperative treatment was standardized. The median time interval to complete epithelial closure was 2 days. According to their spherical equivalent, patients were divided in two groups: group 1 with myopia < or = 6 D (n = 28), group 2 with myopia more than 6 D (n = 20). Examination of UVA and CVA were performed preoperatively and on days 3, 7 as well as 1 month, 3 and 6 months postoperatively.

RESULTS

On day 3 after surgery UVA was 0.43 +/- 0.21 for group 1 with myopia < or = 6 D, and 0.36 +/- 0.14 for group 2 with myopia more than 6 D. The UVA was stable after 3 months (0.92 +/- 0.29 and 0.66 +/- 0.20, respectively), the CVA was stable after 1 month (1.04 +/- 0.18 and 0.86 +/- 0.19, respectively). After surgery, the UVA increased by +0.73 +/- 0.25, whereas the CVA increased by +0.05 +/- 0.10 for the whole group. The difference comparing pre- and postoperative UVA was significantly higher in group 1 (0.81 +/- 0.22) than in group 2 (0.60 +/- 0.26) (p = 0.002). However, postoperative CVA values were not significantly different from preoperative values in both groups after 6 months (p = 0.3).

CONCLUSION

Useful uncorrected visual acuity is normally achieved at day 3 after PRK in eyes with mild to moderate myopia. With higher degrees of myopia the uncorrected visual acuity does increase slower towards a lower level. One of the reasons for this phenomenon might be a significant regression of the refractive effects during the first half year after surgery.

[Transplant endothelium and measuring corneal thickness after non-high-risk keratoplasty with briefly or long-term preserved corneal donor tissue]

PURPOSE

The corneal endothelial cell density is essential for the pump function and the transparency of grafts after penetrating keratoplasty (PK). The purpose of this study was to assess corneal endothelial cell density after non-high-risk PK and to check for possible correlations with storage parameters of the donor corneas using two different storage methods.

PATIENTS AND METHODS

Endothelial cell density (specular microscope EM 1100, TOMEY, Erlangen) and central corneal thickness (ultrasonic pachymetry SP-2000, TOMEY, Erlangen) were assessed 6 weeks, 3, 6, 9 months and one year postoperatively in 168 non-high-risk PKs. Short-term-preserved donor corneas were used in 89 patients, whereas in 79 patients organ-cultured corneas were used. The donor trephination was performed from the epithelial side using an artificial anterior chamber. The postoperative treatment with topical steroids was standardized. The mean donor post-mortem time was 9.6 +/- 8.0 hours for short-term-preserved and 17.6 +/- 10.5 hours for organ-cultured corneas (p < 0.0001). The storage time was 71 +/- 49 and 380 +/- 167 hours (p < 0.0001), respectively.

RESULTS

Endothelial cell density did not differ significantly between the two storage methods (p > 0.05). At 6 weeks postoperatively, the mean endothelial cell density was 2042 +/- 675 cells/mm2 for short-term-preserved corneas and 1972 +/- 522 cells/mm2 for organ-cultured corneas (p = 0.7). Endothelial cell density did not decrease significantly (p > 0.05) within the observation period of 12 months in both groups (after 12 months: 1868 +/- 957 cells/mm2 and 1638 +/- 643 cells/mm2, respectively). The mean corneal thickness was 542 +/- 50 microns for short-term-preserved and 541 +/- 55 microns for organ-cultured corneas and remainded unchanged during the follow-up of 12 months (542 +/- 42 microns and 521 +/- 43 microns, respectively). Neither the group of short-term-preserved corneas nor organ-cultured corneas showed a significant correlation between endothelial cell density or central cornea thickness with post-mortem time or with storage time of the donor corneas at any postoperative stage (p > 0.1).

CONCLUSION

During the first year after PK, only a small decrease in endothelial cell density was observed in comparison with the 6-weeks finding. The storage method does not seem to affect the short-term changes of endothelial cell density. Further long-term studies are necessary to assess the clinical relevance of these observations.

Quantification of aqueous flare after phacoemulsification with intraocular lens implantation in eyes with pseudoexfoliation syndrome

BACKGROUND

Impairment of the blood-aqueous barrier is a frequent finding in eyes with pseudoexfoliation syndrome (PEX).

OBJECTIVE

To perform noninvasive quantification of aqueous flare using the laser flare-cell meter to analyze blood-aqueous barrier breakdown following phacoemulsification with intraocular lens implantation in eyes with and without PEX.

METHODS

After other conditions that might account for impairment of the blood-aqueous barrier were excluded, 11 eyes with PEX and 11 eyes with senile cataract without PEX were included in the study. Aqueous flare was quantitatively determined using a laser flare-cell meter preoperatively as well as 1, 3, and 5 days postoperatively. Phacoemulsification with posterior chamber intraocular lens implantation was performed by one surgeon.

RESULTS

On the first postoperative day, flare values (calculated as mean+/-SD photon counts per millisecond) in eyes with PEX were higher (42.2+/-21.3) than in eyes without PEX (30.6+/-15.1) (P>.05). On days 3 and 5, postoperative flare values decreased slowly in eyes with PEX (23.9+/-7.4 and 21.2+/-5.7 photon counts per millisecond, respectively) and were significantly higher than in eyes without PEX (14.8+/-5.4 and 10.5+/-1.4 photon counts per millisecond, respectively) (P<.05).

CONCLUSIONS

Breakdown of the blood-aqueous barrier is significantly more extensive in eyes with PEX and may be an important risk factor for early postoperative complications. The altered response to surgery should be considered in eyes with PEX.

Underestimation of intraocular lens power for cataract surgery after myopic photorefractive keratectomy

OBJECTIVE

To assess the validity of corneal power measurement and standard intraocular lens power (IOLP) calculation after photorefractive keratectomy (PRK).

DESIGN

Nonrandomized, prospective, cross-sectional, clinical study.

PARTICIPANTS

A total of 31 eyes of 21 females and 10 males with a mean age at the time of surgery of 32.3 +/- 6.6 years (range, 24.4-49.5 years).

INTERVENTION

Subjective refractometry, standard keratometry, TMS-1 corneal topography analysis, and pachymetry were performed before and 15.8 +/- 10.4 months after PRK for myopia (n = 24, -1 .5 to -8.0 diopters [D], mean -5.4 +/- 1.9 D) or myopic astigmatism (n = 7, sphere -2.0 to -7.5 D, mean -4.4 +/- 1.9 D; cylinder -1.0 to -3.0 D, mean -1.9 +/- 0.7 D). The IOLP calculations were done using two different formulas (SRK/T and HAIGIS).

MAIN OUTCOME MEASURES

Keratometric power (K) and topographic simulated keratometric power (TOPO) as measured (Kmeas, TOPOmeas) and as calculated according to the change of power of the anterior corneal surface or according to the spherical equivalent change after PRK (Kcalc, TOPOcalc), IOLP for emmetropia, and postoperative ametropia for calculated corneal powers were assessed in a model.

RESULTS

After PRK, mean Kmeas and TOPOmeas were significantly greater (0.4-1.4 D, maximum 3.3 D) than mean KRcalc and TOPOcalc (P < 0.0001). On average, the relative flattening of the cornea after PRK was underestimated by 14% to 30% (maximum, 83%) depending on the method of calculation. The mean theoretical IOLP after PRK ranged from + 17.4 D (SRK/T, TOPOmeas) to +20.9 D (HAIGIS, Kcalc) depending on the calculation method for corneal power and IOLP calculation formula used. For both formulas, IOLP values using keratometric readings were significantly higher (>1 D) than IOLP values using topographic readings (P < 0.0001). The theoretically induced mean refractive error after cataract surgery ranged from +0.4 to +1.4 (maximum, +3.1) D. Corneal power overestimation and IOLP underestimation correlated significantly with the spherical equivalent change after PRK (P = 0.001) and the intended ablation depth during PRK (P = 0.004).

CONCLUSIONS

To avoid underestimation of IOLP and hyperopia after cataract surgery following PRK, measured corneal power values must be corrected. The calculation method using spherical equivalent change of refraction at the corneal plane seems to be the most appropriate method. In comparison with this method, direct power measurements underestimate corneal flattening after PRK by 24% on average. Use of conventional topography analysis seems to increase the risk of error. However, because this study is retrospective and theoretical, there is still a need for a large prospective investigation to validate the authors' findings.

Quantification of blood--aqueous barrier breakdown after trabeculectomy: pseudoexfoliation versus primary open-angle glaucoma

PURPOSE

Impairment of the blood-aqueous barrier in unoperated eyes with pseudoexfoliation syndrome has been demonstrated by fluorescein angiography, fluorophotometry, measurement of aqueous flare, and determination of aqueous protein. We performed noninvasive quantification of aqueous flare using the laser flare-cell meter to compare blood-aqueous barrier breakdown after trabeculectomy in eyes with primary open-angle glaucoma (POAG) and in eyes with pseudoexfoliative glaucoma (PEX).

METHODS

Twenty eyes with PEX and 20 eyes with POAG were included in the study. Trabeculectomy was performed by two surgeons according to a standard trabeculectomy technique. Intra- and postoperative treatments were identical in both groups. Aqueous flare was quantitatively determined using the laser flare-cell meter FC-1000 (Kowa, Tokyo, Japan) before and 3, 5, 7, and 9 days after trabeculectomy. Absolute flare and difference between post- and preoperative flare values were statistically analyzed using the Mann-Whitney U-Test for independent samples.

RESULTS

Before surgery, aqueous flare values were significantly higher in PEX than in POAG. On days 3, 5, 7 and 9 after surgery, flare values were significantly higher in eyes with PEX than in eyes with POAG. Absolute differences between post- and preoperative flare values also were significantly higher in eyes with PEX, but this was not true for percentage values.

CONCLUSION

These results show that substantial blood-aqueous barrier breakdown occurs in eyes with PEX after trabeculectomy. These alterations may contribute to early or late complications of trabeculectomy and indicate the need for close postoperative follow-up evaluation in eyes with PEX.

Quantification of blood-aqueous barrier breakdown after photorefractive keratectomy for myopia

BACKGROUND

Photorefractive keratectomy (PRK) using the excimer laser is a well-established surgical technique for correction of mild to moderate myopic refraction errors in case of spectacle or contact lens incompatibility. As it is still uncertain whether this procedure causes intraocular inflammatory changes, it was the purpose of this study to quantify breakdown of the blood-aqueous barrier following PRK and to look for possible correlations with clinical parameters.

PATIENTS AND METHODS

Aqueous flare was quantified using the laser flare-cell meter after medical pupil dilation preoperatively and on days 1, 3 and 7 as well as 1 month and 3 months following PRK with a 193-nm excimer laser (MEL 60, Aesculap-Meditec) in 37 eyes of 22 patients. The preoperative spherical equivalents were -4.4 +/- 3.1 D (range -1.5 to -8.0 D). Pre-, intra- and postoperative treatment was standardized.

RESULTS

Preoperatively, aqueous flare values were 3.9 +/- 0.8 photon counts/ms and showed no significant correlation with the spherical equivalent (p > 0.1). Postoperatively, aqueous flare rise was very small with flare values not significantly higher than preoperative values. All postoperative flare values were below the normal limit (< 8.0 photon counts/ms). Flare was highest on day 3 after PRK surgery. There was no statistically significant correlation between aqueous flare and depth of stromal ablation. The number of aqueous "cells" did not increase following PRK at any postoperative follow-up examination.

CONCLUSION

Our results indicate that PRK in mild to moderate myopia does not cause a significant breakdown of the blood-aqueous barrier.

Detection of a common mutation in factor V gene responsible for resistance to activate protein C causing predisposition to thrombosis

Hereditary predisposition to thrombosis due to activated protein C resistance (APCR) has been attributed to a missense mutation in the factor V gene at nucleotide 1691 (G to A), causing replacement of arginine at codon 506 with glutamine. Using an RFLP-PCR assay to detect this mutation, we measured a prevalence of 3.3% in healthy Caucasians and 1.25% in healthy African-Americans. In addition, we evaluated a total of 90 consecutive specimens submitted to the coagulation laboratory at the Medical College of Virginia for the presence of this mutation. We compared our results for 78 of these specimens with the values measured by a modified partial thromboplastin assay, the COATEST. Twelve of the 90 samples could not be tested using the COATEST because the patients were undergoing anticoagulant therapy. One of the latter 12 specimens was positive by the RFLP-PCR test. Using the genetic test as the definitive assay and the cutoff value established for distinguishing between normal and abnormal results by the COATEST, the COATEST had a sensitivity of 50% and specificity of 93% for the detection of factor V mutation. Analysis of the 90 samples stratified by ethnic groups revealed a frequency of mutation of 13.3% for Caucasians and 6.88% for African-Americans, although with the present sample size, the difference was not statistically significant. Although the COATEST is technically simpler to perform than the genetic test for diagnosing the presence of the factor V mutation, its use for this purpose is limited due to low sensitivity. Thus where this disorder is clinically suspected, submission of the specimen directly for genetic testing by RFLP-PCR or equivalent assay should be considered.

[Laser-tyndallometry in eyes with acute retinal necrosis syndrome. Erlanger Laser-tyndallometry study group]

PURPOSE

Acute retinal necrosis syndrome (ARN) is a rapidly progressive viral necrotic retinitis. We used noninvasive measurement of aqueous flare to quantify blood-ocular barrier breakdown in eyes with ARN und to follow the inflammatory activity and treatment effects.

PATIENTS AND METHODS

We report on seven patients (5 males und 2 females, age: 16 to 57 years) with ARN that were treated in our institution between 1991 to 1996. Aqueous flare was quantified regularly during treatment using the laser flare-cell meter (Kowa, FC-1000) following pupillary dilation.

RESULTS

Aqueous flare was highly significantly increased in eyes with ARN (145.5 +/- 139.7, range 30 to 367 photon counts/ms). Contralateral, unaffected eyes showed normal flare values (3.6 +/- 0.8 photon counts/ms, p < 0.0001; normals: 4.1 +/- 1.1 photon counts/ms). Flare values correlated with inflammatory activity before and during antiviral treatment. In two patients with ARN caused by herpes simplex-virus aqueous flare values were extremely increased (367 and 316 photon counts/ms), and retinal necrosis was rapidly progressive despite antiviral therapy. One patient developed early ARN in his contralateral eye with flare values increasing from 3.5 to 22.0 photon counts/ms, which quickly normalized following antiviral treatment.

CONCLUSIONS

Measurement with the laser flare-cell meter allows quantification of blood-ocular barrier breakdown in eyes with ARN und may be useful for monitoring inflammatory activity during treatment.

[Design and preliminary results of the Erlanger non-high-risk penetrating-keratoplasty study]

PURPOSE

The purpose of this prospective study is to examine the non-high-risk penetrating keratoplasty clinically, tyndallometrically and immunological-serologically in order to learn more about the pathogenesis, early symptoms and therapy monitoring of corneal graft rejection.

PATIENTS AND METHODS

Since february 1997, patients undergoing non-high-risk-PK have been enrolled in this prospective study. Examinations are done preoperatively and in well-defined postoperative gates (6 weeks, 3 months, 6 months, etc.) and include clinical assessments, corneal topography, laser-tyndallometry, corneal endothelial cell count and corneal pachymetry. Preoperatively as well as at each postoperative examination, 10 ml serum and perioperatively corneoscleral donor tissue are collected and frozen (-80 degrees C) to allow immunological and serological examinations in case of graft rejection later. A relational data base (MS Access) guarantees complete and homognous standardized clinical and serological data. We randomised our patients with respect to duration of topical steroid therapy in standard situations (short-time vs. long-time) as well as for systemic steroid therapy (bolus group vs. tapering group) in case of a graft rejection in 2 treatment groups.

RESULTS

Up to March 1998, 99 patients have been enrolled in this prospective study. Our report includes the first consecutive 55 patients (25 female, 30 male, recipient age 56.9 +/- 19.4 years, donor age 57.0 +/- 19.9 years). Up to now (follow-up 2.5 +/- 2.1, maximum of 7.3 months) we did not observe immunologic graft rejections. In one patient a primary graft failure occurred. Laser tyndallometry showed a reduction of blood-aqueous barrier breakdown from 6 weeks postoperatively (9.3 +/- 5.7 photon counts/msec) to 3 months postoperatively (6.8 +/- 3.5 photon counts/msec).

CONCLUSION

This prospective randomized clinical and immunological study after non-high-risk-PK is supposed to give more information about pathogenesis, early symptoms and therapy monitoring of graft rejection after elective PK. The concept and design of this study are described. Preliminary data may give significant results in a few years.

Quantification of aqueous melanin granules in primary pigment dispersion syndrome

PURPOSE

Aqueous melanin granules are essential in the pathogenesis of pigment dispersion syndrome and pigmentary glaucoma. We quantified aqueous melanin granules with the laser flare-cell meter in patients with pigment dispersion syndrome, assessed the measurement reproducibility, and correlated the numbers with clinical findings.

METHODS

Aqueous melanin granules were counted by means of the cell count mode of the laser flare-cell meter (KOWA FC-1000; Kowa, Tokyo, Japan) in 42 eyes of 21 patients with primary pigment dispersion syndrome under three conditions (undilated pupils, dilated pupils, after exercise). The reproducibility of the measurements was determined with the intraclass correlation coefficient. A control group of 40 age- and sex-matched eyes was also examined after pupillary dilation. The results were correlated with biomicroscopic findings in eyes with pigment dispersion syndrome (retrocorneal Krukenberg spindle, iris transillumination, pigmentation of trabecular meshwork).

RESULTS

Numerous aqueous melanin granules were detected in eyes with pigment dispersion syndrome (mean, 2.9 +/- 3.7 granules/0.075 mm3) but only small numbers were counted in normal eyes (0.2 +/- 0.3, P < .001). Medical pupil dilation caused an additional increase of aqueous melanin granules in pigment dispersion syndrome (6.3 +/- 5.3, P < .001), but not undilated exercise (climbing stairs) (2.9 +/- 3.7, P > .5). The reproducibility of the measurements was very high (intraclass coefficient >0.92). The number of melanin granules correlated with the degree of Krukenberg spindle (r = .61, P = .004) and with iris transillumination (r = .69, P = .001).

CONCLUSIONS

Quantification of aqueous melanin granules yields reproducible results and shows increased numbers in pigment dispersion syndrome, especially after pupillary dilation. Aqueous melanin granule quantification may be useful for evaluating eyes with pigment dispersion syndrome and for assessing treatment effects.

Aqueous flare in retinitis pigmentosa

BACKGROUND

The purpose of this study was to quantify blood-ocular barrier impairment by measuring aqueous flare in retinitis pigmentosa (RP) and to search for clinical correlations.

METHODS

Forty-nine patients (94 eyes) with RP and 85 normal controls were examined. Aqueous flare was quantified with the noninvasive laser flare-cell meter (FC-1000, Kowa, Japan). Degrees of cystoid macular edema (CME), vitreous pigment dusting (VPD), intraretinal migration of retinal pigment epithelium, and waxy pallor of the optic nerve head were determined semiquantitatively by biomicroscopy. Data were analyzed using the t-test the Mann-Whitney U-test, the chi-squared test and regression analysis by taking into account the dependency of data from two eyes of the same patients.

RESULTS

Aqueous flare (photon counts/ms) was significantly higher in RP (mean 10.11 +/- 3.53) than in normals (3.89 +/- 0.94; P < 0.001). Clinically significant CME was present in 26% of eyes with RP, being significantly more frequent in autosomal dominant RP (11 of 16 eyes, 69%) than in other variants (17%; P < 0.005). Multivariate analysis revealed that CME was most strongly associated with flare values (r = 0.84), P < 0.01), whereas--after adjusting for CME--correlations between aqueous flare and other clinical findings did not reach significance.

CONCLUSION

RP eyes show increased aqueous flare values, indicating impairment of blood-occur barriers. This appears to be associated with CME and with autosomal dominant RP.

Blood-aqueous barrier after mechanical or nonmechanical excimer laser trephination in penetrating keratoplasty

PURPOSE

To analyze whether nonmechanical trephination with an excimer laser influences post-operative blood-aqueous barrier breakdown after penetrating keratoplasty.

METHODS

Patients undergoing penetrating keratoplasty for keratoconus or Fuchs dystrophy were prospectively randomly assigned to trephination by either excimer laser or conventional mechanical handheld motorized trephine. All surgery was performed by one surgeon, and preoperative, intraoperative, and postoperative treatment was identical in both groups. Aqueous flare was quantitatively determined postoperatively in a masked fashion by laser flare-cell meter. For statistical analysis, the nonparametric Wilcoxon-Mann-Whitney test was used.

RESULTS

A total of 52 eyes of 52 patients were examined (Fuchs dystrophy, 10; keratoconus, 42). During the early postoperative period (days 3 to 9), eyes that had undergone nonmechanical excimer laser trephination (25/52) showed significantly (P < .005) lower flare values than did eyes that had undergone mechanical trephination (27/ 52). In both groups, flare values returned to normal levels by 6 weeks postoperatively.

CONCLUSION

Early postoperative blood-aqueous barrier breakdown is less pronounced after penetrating keratoplasty with nonmechanical excimer laser trephination.

Pseudoexfoliation syndrome and secondary cataract

AIM/BACKGROUND

The pseudoexfoliation (PEX) syndrome is frequently associated with impairment of the blood-aqueous barrier. This study analysed if this might stimulate secondary cataract following cataract extraction.

METHODS

This historical cohort study included 197 eyes of 197 patients (99 with and 98 without PEX) that underwent extracapsular cataract extraction with posterior chamber lens implantation (PMMA optic) between 1985 and 1991. Secondary cataract was defined as opacification of the axial posterior capsule and decrease of visual acuity by two or more lines. Mean follow up was 23.8 months. For statistical analysis, the Kaplan-Meier method and multivariate Cox regression analysis were used.

RESULTS

Secondary cataract was observed within 24 months in 35% (SD 7%) of all eyes, and was significantly more frequent in eyes with PEX (45 (11)%) than in eyes without PEX (24 (9)%, p < 0.03). Eyes with diabetes mellitus (n = 32) showed a significantly lower frequency of secondary cataract (11 (11)%) than eyes without diabetes mellitus (39 (8)%, p < 0.01). The influences of sex, open angle glaucoma, type of cataract, surgeon, positioning of IOL, and phacoemulsification versus nuclear expression on secondary cataract did not reach statistical significance.

CONCLUSION

The higher frequency of secondary cataract could be considered as another potential complication of cataract surgery in eyes with PEX.

Physician behavioral response to a Medicare price reduction

OBJECTIVE

To investigate at the individual practice level physician behavioral responses to the Medicare fee reductions mandated in the Omnibus Budget Reconciliation Act of 1989. Symmetric and nonsymmetric behavioral responses are modeled and investigated.

DATA SOURCES

Volume index calculated from data in the Part B Medicare Annual Data (BMAD) Provider Files for 1989 and 1990. The pricing data are from the Procedure Files.

STUDY DESIGN

A fixed-effects model in carrier and in specialty is employed.

DATA COLLECTION

No direct data collection is required as BMAD files are used in the study. Price and volume variables are expressed as Fisher indexes of change.

PRINCIPAL FINDINGS

The results show nonsymmetrical behavioral response because practices that did not face significant fee reductions do not exhibit behavioral change. By contrast, losers partially compensate for the fee reductions. For every dollar cut in their fees, physicians recoup approximately 40 cents by increasing volume. Loser behavioral responses vary by specialty.

CONCLUSIONS

The presence of a volume response suggests that price control alone is not sufficient to cap rising healthcare costs. This indicates that additional or other tools must be considered if cost containment is to be attained.

[Value of blue-on-yellow VEP for early diagnosis in suspected glaucoma. Biostatistical considerations and results]

BACKGROUND

In the Erlangen glaucoma study, the blue-on-yellow VEP was shown to be able to discriminate between controls and manifest glaucoma patients. SCIENTIFIC QUESTIONS AND AIMS: In our investigation, we assessed the validity of the blue-on-yellow VEP for early diagnosis of glaucoma. With this aim, we compared different subgroups of glaucoma suspects. The main issue of the investigation was the biostatistical aspects of early diagnosis of glaucoma.

MATERIAL, METHODS AND RESULTS

Within a group of patients who were suspected of having ocular hypertensive glaucoma without visual field loss we compared 109 patients with optic disc damage [preperimetric (PPM) 47 +/- 11 years] and 91 patients without optic disc damage [ocular hypertension (OHT) 45 +/- 10 years]. We evaluated the N 1-amplitude and the peak latency of the blue-on-yellow VEP. The peak latency was significantly longer in the PPM group (first examination: OHT 118 +/- 9.5 ms, PPM 122.0 +/- 10.5 ms; second examination: 119.1 +/- 7.4/121.9 +/- 11.0 ms; third examination: 118.5 +/- 9.1/122.4 +/- 10.9 ms). The amplitude was reduced in the PPM group (P = 0.08). The differences between the two groups only allowed limited individual separation: (sensitivity of 42% for advanced optic disc damage with 80% specificity among OHT patients).

CONCLUSIONS

The reduced sensitivity of a diagnostic procedure within a group of glaucoma suspect patients compared with patients with manifest glaucoma might be explained by: (1) possible misclassifications of patients and (2) a smaller degree of loss of visual function in the early stages of the disease.

The effect of stimulus size on human cortical potentials evoked by chromatic patterns

The effect of stimulus size on the pattern onset-offset visual evoked potential elicited with stimuli of two different wavelengths is studied under intensive yellow adaptation: (1) The onset response obtained with a 460 nm pattern is of negative polarity (N1) and saturates in amplitude with a stimulus radius of 7 deg. The onset response obtained with a 550 nm pattern is of positive polarity and continues to increase up to the maximum size (32.2 deg). (2) The peak time of N1 (460 nm) decreases with increasing stimulus size, that of P1 (550 nm) remains constant. These results are discussed as reflecting either varying retinal and brain anatomy, or cone activity, color-opponent activity, or luminance contrast activity.

[Tyndallometry and cell count in the anterior chamber in retinal detachment]

BACKGROUND

Aim of this study was the investigation of changes of aqueous flare and cells in eyes with retinal detachment.

PATIENTS AND METHODS

We examined 62 eyes of 61 patients with retinal detachment (56 eyes with rhegmatogenous retinal detachment, 6 eyes with traction retinal detachment; 51 eyes without and 11 eyes with clinical signs of proliferative vitreoretinopathy (PVR) stage C) with the laser flare-cell meter (LFCM) and compared the results with clinical findings and with the results of a control group.

RESULTS

The flare values as well as the cell count of all eyes with retinal detachment were significantly elevated (p < 0.0001) in comparison to those of the control group. In eyes with PVR a significant elevation of flare values in comparison to eyes without PVR appeared (p = 0.0052). A slight correlation was found between the extension of the detachment and the flare values and the cell count, respectively. In cases with rhegmatogenous retinal detachment a significant elevation of the cell count was found if the largest break was localized in the upper hemisphere (p = 0.03) or if the macula was affected (p = 0.02). In rhegmatogenous retinal detachment, the cell count correlated slightly with the age of the patients (r = 0.3, p = 0.02), and flare values correlated with the height of the detachment (r = 0.28, p = 0.04).

CONCLUSIONS

Our results demonstrate a breakdown of the blood-ocular barriers in eyes with retinal detachment and an elevation of corpuscular elements in aqueous as manifestations of pseudouveitis. In eyes with PVR the alteration of blood-ocular barriers seems to be more extensive than in eyes without PVR indicating a possible role of the LFCM for early detection of PVR.

[A clinical comparative study of tyndallometry using 2 laser flare meters]

BACKGROUND

The laser flare meter FM-500 (Kowa, diode laser, 670 nm) is a simplified version of the laser flare-cell meter FC-1000 (Kowa, He-Ne laser, 632.8 nm). the aim of this study was to compare flare measurements of the laser flare meter FC-500 with the established laser flare-cell meter FC-1000 and to determine the reproducibility of both instruments in vivo.

PATIENTS AND METHODS

Ten eyes of 10 normal subjects (mean age 32.2 +/- 8.0 y) and 21 eyes of 21 patients (mean age 36.7 +/- 17.2 y) with various forms of uveitis were included in the study. Aqueous flare was quantified using the laser flare-cell meter FC-1000 and the laser flare meter FM-500 by one examiner under comparable conditions. The selection of eyes as well as the order of the examinations were done in a randomized fashion. Measurements with both instruments were repeated the following day in normal eyes. Statistical analysis was done using linear regression analysis, intraclass correlation and U-test.

RESULTS

Flare values (photon counts/ms) did not differ significantly between the instruments either for normal eyes (3.3 +/- 0.4 vs 3.5 +/- 0.6) or for eyes with uveitis (16.2 +/- 9.0 vs 16.4 +/- 8.7). A high correlation of flare counts between both instruments was observed in normal eyes (r = 0.73, p < 0.001) and a very high correlation in eyes (R = 0.99, p < 0.0001) with mildly to moderately increased counts (< 50 photon counts/ms). Differences between flare values of both instruments were -0.17 +/- 0.4, range -0.8 +/- 0.6 in the normal eyes and -0.23 +/- 1.38, range -3.1 +/- 3.4 in the patients with mildly to moderately increased flare counts. However, flare counts differed for very high aqueous flare in one patient with acute fibrinous iridocyclitis with the FM-500 indicating higher values. The intraclass correlation coefficients were 0.70 for the FC-1000 and 0.76 for the FM-500 in normal eyes and 0.99 for both instruments in eyes with uveitis.

CONCLUSIONS

In eyes without or with mild to moderate breakdown of the blood-aqueous barrier, the two instruments give comparable results. However, measurements may differ in eyes with high flare readings.

[Tyndallometry for follow-up of iodine-125 brachytherapy of uveal malignant melanomas. Report of 2 patients]

BACKGROUND

Previous studies that used the noninvasive laser flare-cell meter (LFCM) have demonstrated impairment of the blood-aqueous barriers in eyes with uveal melanoma. Herein we report the use of the LFCM in the follow-up of brachytherapy in 2 patients after radiation therapy with iodine 125 for choroidal melanoma.

CASE REPORT

Two women (59-and 57-years-old) with choroidal melanoma who were treated with iodine 125-plaque, were followed-up for 24 and 36 months, respectively. Complete ophthalmological examination including tyndallometry and echography were performed regularly. Following radiation, patient 1 showed decreasing flare values, that returned to normal level one year after radiation (5.9 photon counts/ms). The decrease in flare values correlated with fundoscopic and ultrasonographic signs of tumor regression. After 14 months, flare values suddenly increased up to 15 photon counts/ms, and fluorescein angiography revealed signs of radiation retinopathy. In patient 2, flare values (18.0 photon counts/ms) did not decrease after radiation but showed further increase one year after radiation (39.0 photon counts/ms). Slitlamp biomicroscopy revealed segmental iris neovascularization from 6 to 9 hours, corresponding to the site of the previous plaque application.

CONCLUSIONS

Measurement of aqueous flare with the LFCM appears to be a useful ancillary diagnostic method in following patients after radiation therapy for uveal melanoma. In eyes that show an increase of aqueous flare months or years after radiation therapy, recurrence of the tumor, radiation retinopathy and iris neovascularization should be excluded.