In ophthalmology new possibilities for the use Nd:YAG laser

Results of the technical development in laser technology created new possibilities in ophthalmic surgery, too. The easy access to various lasers offers an extraordinary opportunity for eye surgeons. At the Department of Ophthalmology of the University Medical School of Debrecen we performed 1400 laser treatments in 1996. Out of that 1100 were retinal Argon laser coagulations because of diabetic retinopathy, 200 YAG laser capsulotomies because of secondary cataract, and 30 laser iridotomies because of glaucoma. Additional 70 laser treatments were performed for special indications. During the laser treatment of the retina and the choroid we use Argon gas lasers, whereas the Nd:YAG laser used in the anterior segment of the eye is a solid-state laser. Our pulse mode modus synchronized Nd:YAG apparatus can produce megawatts of energy in nanoseconds. Authors give an account of the Nd:YAG lasers' possibilities in therapy (capsulotomy, iridotomy), present the most frequent indications of treatments in 1996, and compare it with international literature data. Authors demonstrate the newest principles of the Nd:YAG laser treatment of secondary membranes that are occasionally formed in the anterior chamber especially in the area of the pupil following cataract surgery.

[Vitrectomy and proliferative diabetic retinopathy. Apropos of 66 eyes]

PURPOSE

We report a retrospective study about vitrectomy in diabetic patients and the analysis of anatomical and functional results after surgery.

METHODS

We studied 66 eyes of 52 diabetic patients who underwent pars plana vitrectomy. Vitrectomy was performed for nonclearing intravitreous hemorrhage in 75% of eyes and for tractional macular retinal detachment in 14% of eyes.

RESULTS

After vitrectomy for intravitreous hemorrhage, visual acuity increased in 84% of eyes with more than 5/10 in half the cases. After vitrectomy for tractional retinal detachment, visual acuity increased or became stable in only 55% of eyes. The major complication of surgery was recurrence of intravitreous hemorrhage. A new surgery was not necessary in most cases. Neovascular glaucoma, phtysis, retinal detachment and cataract were the other complications of surgery.

CONCLUSION

Visual prognosis after vitrectomy performed in complicated diabetic retinopathy depends on the final macular function. Surgery for intravitreous hemorrhage without macular detachment produced in most of cases a good visual acuity. On the other hand, vitrectomy for tractional macular retinal detachment was followed by poor visual prognosis. After recurrent intravitreous hemorrhage, a new surgical procedure is possible with good visual results in most cases, even if several procedures are necessary.

[Extracapsular extraction and posterior chamber implantation in diabetics. Prospective study of 198 eyes]

PURPOSE

Visual results and retinal changes in diabetic patients who underwent cataract surgery.

METHODS

In a prospective study we followed up 198 eyes of diabetic patients who underwent cataract surgery for at least six months postoperatively. Pre and postoperative retinal status were assessed by clinical examination and fluorescein angiography. Per and postoperative complications and the evolution of visual acuity were noted.

RESULTS

In 83.3% of eyes, visual acuity improved by two or more lines. In 59.6% of patients, visual acuity at six months was more than 6/15. The quality of visual outcome diminished with the severity of retinopathy, but in the most serious cases, lens extraction allowed fundus observation and treatment. Inflammatory complications, posterior capsule opacification and cystoid macular oedema were significantly more frequent in cases of preoperative diabetic retinopathy than in normal fundus. We observed few aggravations of the diabetic retinopathy, but underline the high frequency of cystoid macular edema in diabetic patients.

CONCLUSION

Visual results are good in diabetic patients with mild retinopathy and, in severe cases, surgery allows retinal examination and treatment.

[Effect of panretinal photocoagulation on the ocular pulse curve]

BACKGROUND

Most studies on the effects of panretinal photocoagulation (PRPC) on ocular circulation are concerned with retinal circulation. In the present study, we examined the ocular pulse curve after PRPC and determined pulsatile ocular blood flow (an indicator of choroidal circulation) and ocular perfusion pressure.

PATIENTS AND METHOD

In 10 patients with diabetes mellitus (8 with type II and 2 with type I; mean age 64 yrs) and severe, hitherto untreated, bilateral proliferative diabetic retinopathy, an intensive unilateral PRPC with 1500 argon laser burns (spot size: 500 mu) was performed in 2 sessions (interval: 3 wks). Before and-in 3-wk intervals-up to 9 wks after onset of treatment, an ocular pulse curve was recorded using oculo-oscillo-dynamography, and the following variables were determined: ocular pulsation amplitude (OPA), pulsatile ocular blood flow (POBF), systolic ophthalmic artery pressure (SOAP), and systolic ocular perfusion pressure (SOPP).

RESULTS

PRPC led to a reduction of OPA and POBF in relation to the untreated contralateral eyes. 3 wks after the 1st coagulation, the reduction averaged 20% (OPA) and 19.1% (POBF). The maximum reduction was found 9 wks after onset of treatment (6 wks after the 2nd coagulation) and amounted to 29.9% and 29.2%, respectively. The differences between photocoagulated and untreated eyes were highly significant on average (P < 0.01; ANOVA) as well as for the time course (P < 0.001). SOAP and SOPP were not changed significantly during PRPC.

CONCLUSIONS

OPA and POBF are determined by the cardiac cycle-related intraocular volume changes depending predominantly on choroidal blood flow. Thus, the reduction of POBF after PRPC is indicative of a lowered pulsatile choroidal blood flow. The morphological substrate is probably the choriocapillaries closure after photocoagulation described in the literature.

Silicone oil for recurrent vitreous hemorrhage in previously vitrectomized diabetic eyes

AIMS

To investigate the clinical course of vitrectomized patients with recurrent diabetic vitreous hemorrhage who were treated by revitrectomy with silicone oil (SO) as a hemostyptic tamponade.

PATIENTS AND METHODS

Fifteen patients with recurrent vitreous hemorrhage due to proliferative diabetic vitreoretinopathy were included in this retrospective study. All eyes had had at least one vitrectomy prior to use of SO and the retina was completely attached at any time before revitrectomy with SO instillation. Thirteen patients had a blind fellow eye. There were 6 males and 9 females (mean age 62.7 years, range 45-76 years). The mean duration of SO tamponade was 25.8 months (range 9-35 months). The average follow-up period was 30.4 months (range 20-48 months).

RESULTS

Ten out of 15 eyes (66.6%) improved postoperatively, 9 eyes had a visual acuity of > or = 0.02 at the latest follow-up visit. Secondary glaucoma occurred in 4 eyes, leading to phthisis in 1 eye. All 5 phakic eyes developed a cataract.

CONCLUSION

A revitrectomy combined with a long-term hemostyptic SO tamponade offers a chance for restoration of useful visual acuity in diabetic eyes with persistent vitreous-hemorrhage that fails to subside after cryocoagulation and vitrectomy without tamponade. Because of possible visual loss from secondary glaucoma related to intraocular SO this treatment should mainly be considered in patients with a blind fellow eye.

[Limits and possibilities of vitreous body surgery in diabetic retinopathy]

BACKGROUND

Several indications for vitreous surgery for complications of diabetic retinopathy have been established, but there is little well-founded information concerning situations in which visual prognosis is poor and vitreous surgery should not be performed.

MATERIALS AND METHODS

The charts of 389 patients who had undergone vitreous surgery for complications of diabetic retinopathy between 1990 and 1994 were retrospectively reviewed. The minimum follow-up was 6 months with a median of 26 months. Using multivariate logistic regression analysis we studied factors which were correlated with a postoperative visual acuity of less than 5/200. A model was developed predicting the probability of an unfavorable visual outcome in various situations.

RESULTS

Forty-five eyes (12%) had a best postoperative visual acuity of less than 5/200. Risk factors were detachment of the macula, extent of the detachment, iris neovascularisations and the duration of visual loss. For reoperations similar risk factors were found. The chance that an eye with total tractional retinal detachment of more than 6 months duration and with rubeosis of the iris will achieve a postoperative visual acuity of 5/200 or better is only 2%.

CONCLUSIONS

Eyes with total tractional retinal detachment, especially with longer duration of the detachment and rubeosis, have a very poor chance of achieving useful vision and should not be operated.

[Results of pan-retinal argon laser coagulation in proliferative diabetic retinopathy]

To minimize the risk of visual loss and to stop the progression of diabetic retinopathy argon laser treatment is the therapy of choice in proliferative diabetic retinopathy (PDR). The results after panretinal argon laser coagulation (ALC) were studied retrospectively considering visual outcome and frequencies of diabetic ocular complications. In all 95 patients were included in whom laser treatment had been performed due to clinically and angiographically diagnosed proliferative diabetic retinopathy at the Department of Ophthalmology between 1990 and 1994 with a follow-up of at least 1 year. The most frequent diabetic complications observed were vitreous haemorrhage in 9 (or 9.5%) and iris neovascularization in 10 cases (or 10.5%). Rare complications were neovascular glaucoma in 3 patients (or 3.2%) and tractional retinal detachment in 4 patients (or 4.2%). Nearly 70% of the patients maintained or improved visual acuity after laser treatment. The frequency of diabetic complications of PDR after ALC was significantly associated with older age, diabetes type II, longer duration of diabetes and elevated blood pressure.

[The new laser Doppler velocimetry for the measurement of retinal circulation and its clinical application]

We developed a new laser Doppler instrument to measure retinal blood flow. This instrument is equipped with an eye tracking system, which maintains the laser beam on the retinal vessel, thus enabling the measurement of patients with poor visual acuity and poor fixation. In diabetic patients even those without retinopathy, the retinal blood flow decreased compared to the control subjects. This was mainly the result of decreased retinal blood speed and no significant change in the arterial diameter. In diabetic patients requiring panretinal photocoagulation, we studied the regional changes in retinal blood flow following superior or inferior half fundus argon laser treatment, which produced a significant retinal blood flow decrease only in the treated area. We also studied the retinal circulatory changes in retinal branch vessel occlusion. In retinal branch view occlusion, the blood flow in arteries supplying the affected lesion showed 80-90% decrease compared to the arteries supplying the unaffected region. In retinal branch artery occlusion, the retinal blood flow in occluded arteries showed 40-50% decrease compared to the non-occluded arteries. In one patient with retinal branch vein occlusion in whom we measured the retinal blood flow over 18 months, the blood flow increased with the development of collateral vessels. The results showed that retinal circulatory abnormalities can be also evaluated quantitatively during the course of retinal vascular occlusive disease by our newly developed laser Doppler instrument, which proved that this instrument is a clinically very useful tool.

Cataract surgery and YAG-laser capsulotomy following vitrectomy for diabetic retinopathy

The present study was initiated to assess time-course and risk factors for the development of cataract and posterior-capsule opacification as well as complications of cataract surgery and YAG-laser capsulotomy following vitrectomy for diabetic retinopathy. The charts of all patients undergoing vitrectomy for diabetic retinopathy during a 5-year period in a university eye hospital were retrospectively reviewed. The course of 306 consecutive eyes in which the lens was retained during vitrectomy was analyzed for subsequent cataract surgery and YAG-laser capsulotomy. The first 6 months after cataract or YAG-laser surgery were examined for the occurrence of complications. Data were analyzed with regard to the time course using Kaplan-Meier life-table analysis. The proportion of eyes that underwent cataract surgery after vitrectomy increased nearly linearly with time, approaching 75% after 5 years. Silicone tamponade (relative risk 1.9; P = 0.0005) and transscleral retinal cryotherapy (relative risk 1.4; P = 0.003) were risk factors for subsequent cataract surgery. No significant cataractogenous effect of intravitreal gas as compared with balanced salt solution was found. YAG-laser capsulotomy was performed in 60% of vitrectomized diabetic eyes within 2 years but in only 10% of nondiabetic controls (P < 0.0001). Within 6 months of extracapsular cataract surgery with implantation of an intraocular lens (IOL) in 54 eyes, no serious complication was observed. After YAG-laser capsulotomy, vitreous hemorrhage occurred within 6 months in 6 of 21 eyes. In conclusion, cataract surgery was performed in 75% of the phakic eyes within 5 years of vitrectomy for diabetic retinopathy. Posterior capsular opacification is particularly common in this subset of eyes. No serious complication was observed after extracapsular cataract surgery with IOL implantation, but YAG-laser capsulotomy was associated with an increased risk for vitreous hemorrhage.

Identifying maculopathy after neodymium: YAG membranotomy for dense diabetic premacular hemorrhage

PURPOSE

To assess the value of neodymium:YAG membranotomy in achieving rapid intravitreal dispersion of dense diabetic premacular hemorrhage and allowing the identification and treatment of maculopathy before panretinal photocoagulation (PRP).

METHODS

A pilot study, in which nine eyes with dense diabetic premacular hemorrhages were treated with neodymium:YAG membranotomy, is described. After intravitreal dispersion of premacular blood, fundus examination and fluorescein angiography were performed to identify neovascularization and macular edema. Macular photocoagulation was performed before PRP in eyes with co-existing maculopathy and neovascularization.

RESULTS

Complete intravitreal dispersion was achieved in all eyes within 1 week. Clinically significant macular edema was identified and treated, before PRP, in three eyes. No exacerbation of macular edema occurred after PRP, and visual acuity was stabilized at pre-hemorrhage levels in seven eyes and to within one line in the remaining two eyes. No traction retinal detachments or rebleeding occurred, and vitrectomy was not required in any eye.

CONCLUSIONS

Early neodymium:YAG membranotomy may obviate the need for early vitrectomy for dense diabetic premacular hemorrhage, and allows early identification and treatment of maculopathy, before PRP, thus reducing the risk of exacerbation after PRP. Further studies to evaluate this treatment modality, particularly with respect to long-term visual prognosis, appear warranted.

[Diabetic retinopathy]

Retinal complications of diabetes mellitus are chronic but late functional signs can lead to delayed diagnosis and treatments. Light coagulation (argon laser radiation) is recognized for its efficiency at the stage of "mature" retinopathy, converting the prognosis of a disease which was leading to blindness. Photocoagulation is not used in the early stages (early or strictly posterior pole diabetic retinopathy); partial regression or stabilization can be hoped with intensive medical treatment of diabetes. Treatment of diabetes could become the best preventive treatment. Light coagulation is used at stages when the disease is not reversible (non or preproliferative and proliferative). In tractional retinal detachment surgery remains active, always corresponding to too late treatments. Although pharmacology has progressed (inhibitors of platelet agregation and of non enzymatic glycation) medical therapy remains controversial.

[On the role of the posterior hyaloid membrane in the pathogenesis of and surgery for proliferative diabetic retinopathy]

A total of 278 patients subjected to transciliary vitrectomy for proliferative diabetic retinopathy (PDR) were followed up. Thirty preparations of epiretinal membranes removed in surgery were examined under an optic microscope. Vessels newly forming in PDR were found to grow mainly along the external surface of the posterior hyaloid membrane; they ceased their growth after its removal. The posterior hyaloid membrane is the anatomical object of surgical intervention of PDR. The proliferative form of diabetic retinopathy is never seen in the presence of a naturally occurring or vitrectomy-induced complete posterior hyaloid detachment, that is why if the posterior hyaloid membrane is well detached from the retina in the course of operation, panretinal laser coagulation in the postoperative period is not recommended.

Basic fibroblast growth factor and vascular endothelial growth factor are present in epiretinal and choroidal neovascular membranes

PURPOSE

To determine whether vascular endothelial growth factor and basic fibroblast growth factor, which may be critical mitogens for neovascularization, are present together in human retinal and choroidal neovascular membranes.

METHODS

Light microscopic immunocytochemistry using antibodies against vascular endothelial growth factor, basic fibroblast growth factor, and several cellular "marker" proteins on frozen sections from three choroidal neovascular membranes from patients with age-related macular degeneration, seven surgically excised epiretinal membranes from patients with proliferative diabetic retinopathy, and six epiretinal membranes from patients with nonischemic proliferative retinopathies.

RESULTS

All three choroidal neovascular membranes and all seven epiretinal membranes stained positive for vascular endothelial growth factor. Two choroidal neovascular membranes and six of the epiretinal membranes were positive for basic fibroblast growth factor. The same cells were often positive for both antigens. None of the epiretinal membranes from patients with nonischemic proliferative retinopathies were positive for either growth factor. Many of the cells that demonstrated growth factors were glial cells, vascular endothelial cells, and retinal pigment epithelial cells.

CONCLUSIONS

Colocalization of two growth factors in the same cells of ocular neovascular membranes suggests that more than one growth factor may contribute to pathologic angiogenesis. Growth factors in neovascular tissues are not localized exclusively in the vascular endothelium. Because expression of some growth factors is stimulated by hypoxia, their localization within choroidal neovascular membranes suggests that hypoxia may be an etiologic factor for choroidal as well as for retinal neovascularization.

Prediction of visual acuity after early vitrectomy in diabetics

In proliferative diabetic retinopathy the indication of early vitrectomy remains controversial. At present, no decision rule exists for the assessment of the various factors predicting the postoperative visual outcome. We reviewed 75 vitrectomies in 68 diabetics from our clinic. All vitrectomies were done by one surgeon. In all cases, vitrectomy was indicated because of nonclearing vitreous hemorrhage and/or fibrovascular proliferation. A linear regression model was used to identify factors correlating with the visual outcome. By means of univariate analysis, six of nine clinical variables were found to be associated with the final visual outcome. Dividing the patients into two groups according to their preoperative visual acuity (group 1 hand movement, group 2 better than hand movement), we identified two predictors that were independently associated with the postoperative visual acuity: group 1-the visual acuity of the fellow eye (P < 0.05) and rubeosis iridis (P < 0.05); group 2-the visual acuity of the fellow eye (P < 0.001) and preexisting systemic diabetic vascular disorders (P < 0.01). Based on this model, a formula was derived to predict the visual acuity at 6 months postsurgery. For easier handling the prognostic factors of a poor visual outcome (less than 0.1) were summarized in a flow chart. The test is a useful tool for the preoperative evaluation of various risk factors and, hence, for more reliable prediction of a poor visual outcome. Thus, it may be especially useful to objectify the risk-benefit ratio for early vitrectomy in diabetics.

[Comparative study on diode laser (680 nm) and krypton laser mild photocoagulation--histological findings and therapeutic outcome for diabetic maculopathy]

A histopathological study of macaca monkey retina-choroid was carried out for one month after mild photocoagulation with a diode laser (680 nm) and a krypton laser (647 nm). Both lasers produced the same damage to the outer layer of retina and to the melanocytes of 1/3 of the inner choroid. Mild focal photocoagulation was done for 6 patients (12 eyes) with diabetic maculopathy. The patients were 41 to 67 years old, suffering from diabetes mellitus for 5 to 25 years. The grade of their retinopathy was Fukuda's classification AI, AII, and BI. AII eyes were tested before and 3-6 months after photocoagulation for corrected visual acuity, fluorescein angiography, and visual field sensitivity by Octopus automated static perimetry. Visual acuity was stable in all cases. Central sensitivity was better in 2 eyes and unchanged in 4 eyes in both types of laser photocoagulation. In cases of total loss, one eye was improved, 4 eyes were unchanged and one eye was worsened by diode laser photocoagulation and one eye was improved, 2 eyes were unchanged and 3 eyes were worsened by krypton laser photocoagulation. The diode laser (680 nm) might be as useful for ophthalmic laser treatment as the krypton laser.

Intraocular oxygen tension in eyes with proliferative diabetic retinopathy with and without vitreous

BACKGROUND

Intraocular oxygen tension was measured in the eyes of patients with proliferative diabetic retinopathy with or without vitreous in order to determine local differences in tissue oxygenation in the vitreous cavity before and after vitrectomy.

METHODS

We measured oxygen tension, using polarographic oxygen electrodes, at various intraocular locations in 30 eyes of 29 patients with diabetic traction retinal detachment who were candidates for vitrectomy (pre-vitrectomy group) and 13 eyes of 13 diabetic patients who had previously undergone vitrectomy (post-vitrectomy group).

RESULTS

In the pre-vitrectomy group, oxygen tensions proximal to the neovascularization of the disc and the neovascularization elsewhere were significantly higher than the values obtained at other locations in the vitreous cavity. In the post-vitrectomy group, however, the oxygen tensions at those locations were significantly lower than those in the pre-vitrectomy group. There were no significant differences between the values obtained at any of the measurement locations in the post-vitrectomy eyes.

CONCLUSION

Neovascular tissues in the eyes of diabetic patients demonstrated higher oxygen tensions than non-neovascular tissues. This finding suggests that neovascular issue may compensate for intraocular hypoxia by releasing oxygen from the front. Successful diabetic vitrectomy reduces the activity of the neovascular tissue and equalizes levels of oxygenation in the tissue of the vitreous cavity.

[Retinal vessels before and after photocoagulation in diabetic retinopathy. Determining the diameter using digitized color fundus slides]

BACKGROUND

Retinal vessel diameter is an important parameter in blood flow analysis. Despite modern digital image technology, most clinical studies investigate diameters subjectively using projected fundus slides or negatives. In the present study we used a technique to examine vessel diameters by digital image analysis of color fundus slides. We investigated in a retrospective manner diameter changes in twenty diabetic patients before and after panretinal laser coagulation.

MATERIAL AND METHODS

Color fundus slides were digitized by a new high resolution scanning device. The resulting images consisted in three channels (red, green, blue). Since vessel contrast was the highest in the green channel, we assessed grey value profiles perpendicular to the vessels in the green channel. Diameters were measured at the half-height of the profile.

RESULTS

After panretinal laser coagulation, average venous diameter was decreased, whereas arterial diameter remained unchanged. There was no significant relation between the diameter change and the number of laser burns or the presence of neovascularization.

CONCLUSIONS

Splitting digitized images into color planes enables objective measurements of retinal diameters in conventional color slides.

Vitreous laser absorption following fluorescein angiography in diabetic patients

BACKGROUND

Sodium fluorescein staining of the vitreous following fluorescein angiography may interact with laser photocoagulation.

METHODS

We evaluated the laser absorption by fluorescein in the vitreous when photocoagulation is performed following fluorescein angiography in 15 eyes of nine diabetic patients. Axial fluorescein concentration in the vitreous was measured by a scanning vitreal fluorophotometer. The amount of light absorbed by the fluorescein within the vitreous was calculated according to the Lambert-Beer law.

RESULTS

The mean fluorescein concentration ranged from 2.93 ng cm-3 to 105.16 ng cm-3 at 1 h after injection of fluorescein and from 8.03 to 188.56 ng cm-3 after 4 h. Maximum laser absorption at 488 nm ranged from 6.79% (after 1 h) to 14.53% (after 4 h); at 514.5 nm it ranged from 0.96% to 2.14%; at 532 nm it ranged from 0.03% to 0.07%. At lambda > 550 nm, laser absorption was found to be negligible.

CONCLUSIONS

In order to optimize the effect of photocoagulation, especially during long photocoagulation sessions, argon blue laser (488 nm) should be avoided following fluorescein angiography. Argon green laser (514.5 nm) should be used within 1 h after fluorescein injection. Frequency-doubled Nd:YAG laser (532 nm), krypton laser (647 nm) or semiconductor diode laser (810 nm) may be used at any time.

Hemodynamic alterations in diabetic retinopathy

PURPOSE

This study was designed to examine the characteristics of retrobulbar circulation and the role of glycemic control in patients with diabetes and varying stages of retinopathy.

METHODS

Seventy-three eyes in 37 patients with diabetes were assigned to one of the following four study groups: nonproliferative diabetic retinopathy (non-PDR), proliferative diabetic retinopathy (PDR), post-panretinal photocoagulation (PRP), or preretinopathy (the control group). Color Doppler imaging was used to quantitate peak systolic blood flow velocities of the central retinal artery (CRA), the central retinal vein (CRV), the posterior ciliary artery (PCA) and the ophthalmic artery. Glycated hemoglobin (HbA1c) levels were used as an indicator of glycemic control.

RESULTS

The authors found that the CRA maximum blood flow velocity levels were significantly higher in the pre-retinopathy group (9.8 +/- 2.1 cm/second) than in the non-PDR group (8.1 +/- 2.2 cm/second). In addition, the CRV maximum blood flow velocity levels were significantly higher in the pre-retinopathy group (5.7 +/- 0.9 cm/second) than in both the PDR group (4.8 +/- 1.5 cm/second) and the PRP group (4.9 +/- 1.7 cm/second). No significant differences were seen in blood flow velocity levels of the ophthalmic artery and the PCA among the retinopathy groups. No correlation was found between HbA1c levels and the stage of retinopathy. The presence of systemic hypertension showed no significant effect on blood flow velocities in the various retinopathy groups.

CONCLUSION

This study demonstrates the presence of some circulatory changes in the CRA and the CRV in patients' eyes with diabetic retinopathy when compared with patients' eyes in the pre-retinopathy stage of the disease. These data support the contention that changes in retrobulbar circulation and microcirculation occur during the pathogenesis of diabetic retinopathy. The clinical significance of these findings needs to be determined.

Perioperative analysis of vitreous cell components by immunoimpression cytology

BACKGROUND

Perioperative analysis and classification of vitreous cell components needs a quick method sufficient to prepare both single cells and cellular membranes.

METHODS

In an attempt to clarify the usefulness of immunoimpression cytology we examined 82 eyes with proliferative vitreoretinopathy, proliferative diabetic retinopathy, perforating injuries and contusions.

RESULTS

With this method it is possible to perioperatively obtain cells from surfaces of vitreous membranes as well as single cells in suspension. After staining, various cell types could be differentiated morphologically and on the basis of antibody response to cell markers. We found single cells reacting with the antibodies 27E10 (4 positive of 14 tested), vimentin (2/12), RM 3/1 (2/15), LCA (1/ 11) and, particularly, with antiproliferating cell nuclear antigen (9/18).

CONCLUSION

With immunoimpression cytology it is possible to determine cell surface markers rapidly and accurately from specimens obtained at the time of vitrectomy. The clinical utility of this test will be ascertained by future studies.

Life expectancy of diabetic patients undergoing vitreous surgery

BACKGROUND

Patients with advanced diabetic eye disease are commonly in poor general health. In addition to the ocular status, life expectancy is an important factor in the decision whether and how to perform vitreous surgery. The present study investigates mortality and risk factors for survival in diabetic patients following vitrectomy.

METHODS

The follow up of 332 consecutive patients who underwent vitrectomy for complications of diabetic retinopathy between 1990 and 1994 was studied retrospectively. Survival and risk factors for survival were analysed using the Kaplan-Meier life table method and for multivariate analysis the Cox proportional hazard model.

RESULTS

The 5 year survival rate was 68%. Absence of heart disease was the most important predicting factor for survival. Fifty per cent of the patients with heart disease had died within 3.5 years. Patients without heart disease had a 5 year survival rate of 90%. Other significant, independent risk factors were age and presence of nephropathy.

CONCLUSION

In diabetic patients undergoing vitrectomy the presence of heart disease indicates a poor prognosis for survival. This should be taken into consideration for indications and strategies in cases of vitrectomy.

Preservation of retinal sensitivity in central visual field after panretinal photocoagulation in diabetics

Changes in retinal sensitivity within central 30 degrees following panretinal photocoagulation (PRP) for more severe diabetic retinopathy were investigated. Twenty-five eyes with visual acuity of 0.4 or better and minimal maculopathy were studied prospectively. All underwent PRP in two sittings, and Humphrey field analyzer 30-2 threshold test was done before and 1 week, 1 and 3 months after the treatment. The mean retinal sensitivity threshold was obtained from each hemifield between 15 and 30 degrees and from the central 15 degree area, and the changes in the values were analyzed. Mean sensitivity threshold in the upper visual field at pre-PRP, post-PRP 1 week, 1, 3 months were 15.62, 13.81, 14.31, 14.85, respectively. Values in the lower field were 18.71, 17.25, 17.10, 18.17. Difference between pre-PRP and post-PRP was statistically significant at 1 week but no longer thereafter. Retinal sensitivity within the central 15 degrees remained stable. The data show that retinal sensitivity decreases significantly 1 week after PRP but recovers upto 95% of pre-PRP level over the following 3 months.