Clinicopathological correlation of congenital corneal opacification using ultrasound biomicroscopy

AIM

To investigate the correlation between clinical, high frequency ultrasound biomicroscopy (UBM) and, where possible, histological findings in cases of congenital corneal opacification presenting to the departments of ophthalmology, Great Ormond Street Hospital for Children, London, and the Hospital for Sick Children, Toronto, Canada.

METHOD

22 eyes of 13 children (age range 3-225 days) with congenitally opaque corneas were examined. UBM was performed using the ultrasound biomicroscope (Allergan-Humphrey). All eyes underwent penetrating keratoplasties (PKP) except five. The host corneas were all sent for histological examination.

RESULTS

The final diagnosis in our series was Peters' anomaly in nine cases (70%), corneal dystrophy in two cases (15%), and sclerocornea in two cases (15%). The UBM findings changed the clinical diagnosis in five cases (38%). In these five cases histology was available in four and confirmed the UBM diagnosis in each case. In no case of the 13 where histology was available did it contradict the UBM findings. In two cases a hypoechoic region in the anterior stroma was seen on UBM which correlated histologically with absent Bowman's layer and oedema. In two cases UBM revealed aniridia and in one, congenital aphakia, which was not apparent clinically.

CONCLUSION

UBM examination is not only very useful in evaluating the clinical diagnosis in congenital corneal opacification, it also acts as a preoperative guide in cases undergoing PKP by detecting keratolenticular and iridocorneal adhesions and other ocular abnormalities such as aniridia and congenital aphakia. In all cases where PKP was performed the UBM diagnosis was confirmed histologically. The clinical diagnosis was incorrect in five cases. This has important implications in studies of phenotype/genotype correlation of congenital corneal opacification.

Corneal temperature reversal after storage in Chen medium compared with Optisol GS

PURPOSE

To compare corneal endothelial cell function by measuring corneal thickness during temperature reversal between corneas stored in two different storage media, Optisol GS and Chen Medium (CM).

METHODS

Twenty paired corneas from 10 human donors were randomly assigned for storage at 4 degrees C in Optisol GS (10 corneas) or CM (10 corneas). The storage media were masked, and measurements were done in a masked fashion. After storage for 48 hours, corneal thickness was measured by ultrasonic pachymetry at 2-hour intervals for 12 hours, during which time the corneas were perfused with BSS (balanced salt solution) Plus at 37 degrees C. Scanning electron microscopy of two pairs of corneas from two donors was performed to assess ultrastructural change after 12 hours of warming.

RESULTS

Corneal thickness decreased during the first 4 hours of the warming period and then increased during the 6-to 12-hour warming period. These changes in corneal thickness over time were similar for the two storage media (p = 0.212). Scanning electron microscopy showed greater amounts of endothelial cell disruption in Optisol GS-stored corneas than those stored in CM after 12 hours of warming and perfusion.

CONCLUSIONS

The endothelial pump of corneas stored in CM appear to be as well-preserved as those stored in Optisol GS, although greater endothelial disruption may be present with Optisol GS by scanning electron microscopy. Further studies are required to compare the clinical effectiveness of these two media.

Dislocation of a plate-haptic silicone intraocular lens into the anterior chamber

Posterior dislocation is a well-described complication of plate-haptic intraocular lenses (IOLs). It usually occurs after an opening in the posterior capsule, either intraoperatively or after a neodymium: YAG capsulotomy occurs. We report a case of anterior luxation of a plate-haptic silicone IOL occurring 4 months after uneventful cataract surgery. This case emphasizes the need for a small and continuous capsulorhexis as well as in-the-bag implantation of plate-haptic IOLs.

Detection of hepatitis C virus in the corneas of seropositive donors

PURPOSE

There have been no reported cases of hepatitis C virus (HCV) transmission by corneal transplantation. Previous studies have also shown no correlation between HCV seropositivity and the presence of HCV RNA in the corneal tissues. This study aims to investigate such correlation and to provide further evidence to the possible transmissibility of HCV via corneal grafts.

METHODS

Of the 1,619 potential corneal donors to the Eye Bank of Canada over a 1-year period, 15 tested HCV-positive by the second-generation Abbott HCV enzyme immunoassay (EIA) 2.0 assay. Their sera were further tested with second-generation radio-immunoblot assay (RIBA-II), and their corneas (29 altogether) were processed for identification of HCV RNA using polymerase chain reaction (PCR).

RESULTS

Of the 29 corneas from seropositive donors, HCV RNA was detected in 7 (24.1%).

CONCLUSION

This is the first study in the literature that demonstrates a significant correlation between HCV seropositivity and the presence of HCV in the corneas. Routine HCV serologic testing for all potential corneal donors and rejection of corneal tissues based on HCV seropositivity is certainly justifiable.

Foldable silicone versus poly(methyl methacrylate) intraocular lenses in combined phacoemulsification and trabeculectomy

PURPOSE

To compare the outcome of phacotrabeculectomy with implantation of poly(methyl methacrylate) (PMMA) or foldable silicone intraocular lenses (IOLs).

METHODS

Thirty patients were randomized to receive a 5.5 mm PMMA IOL through a 5.0 mm incision or a foldable silicone IOL (Allergan SI-30) through a 3.2 mm incision. Visual acuity, intraocular pressure (IOP), bleb survival, inflammation, endothelial cell changes, and complications were examined at intervals up to 6 months.

RESULTS

There was no difference between the 2 groups in final visual outcome, final IOP control, bleb survival, and endothelial cell changes. Two months after surgery, there was significantly more inflammation in the silicone IOL group than in the PMMA group (P <. 05). The silicone group had a significantly higher combined complication rate including iris capture, choroidal effusion, and epiretinal membrane formation (P <.05).

CONCLUSIONS

Foldable silicone IOLs were comparable to conventional PMMA lenses in visual outcome, IOP control, bleb formation, and endothelial changes. However, some silicone lenses are associated with an increased risk of recurrence of inflammation and a higher final complication rate in combined cataract and filtration surgery.

Long-term results of transscleral Nd:YAG cyclophotocoagulation for refractory glaucoma postpenetrating keratoplasty

PURPOSE

To determine the effects of noncontact transscleral Nd:YAG cyclophotocoagulation (NCTY) in the treatment of refractory glaucoma postpenetrating keratoplasty (PKP) with respect to intraocular pressure (IOP), corneal graft survival, and reduction of glaucoma medications.

METHODS

The records of all patients treated with NCTY for refractory glaucoma after PKP at the authors' institution over an 11-year interval were reviewed. The LASAG noncontact Nd:YAG laser (Lasag AG; Thun, Switzerland) was used. Approximately 40 laser applications were delivered per eye. Visual acuity, IOP, glaucoma medications, and corneal graft clarity were evaluated.

RESULTS

Fifty-two eyes met the inclusion criterion. The mean pretreatment IOP was 38.7+/-11.9 mm Hg. The mean posttreatment IOP was 15.8+/-9.7 mm Hg. From life table analysis, the probability of having a posttreatment IOP of 21 mm Hg or less with or without medication was 70% at 1 year and 63% at 5 years. The probability of a graft remaining clear was 79% at 1 year and 56% at 5 years. In 85% of patients the visual acuity remained stable, in 11% the visual acuity improved, and in 4% the visual acuity deteriorated after treatment. One patient developed hypotony. Twenty patients (36.5%) were able to discontinue one or more glaucoma medications posttreatment.

CONCLUSION

In this group of patients with PKP glaucoma, NCTY effectively lowered IOP over the long term, with 36.5% of patients discontinuing one or more glaucoma medications. There was, however, a significant incidence of graft failure at 5 years.

Primary localized conjunctival amyloidosis presenting with recurrence of subconjunctival hemorrhage

PURPOSE

To report the ocular presentation and histopathology of a patient with primary localized conjunctival amyloidosis.

METHODS

A 38-year-old woman presented with a recurrence of episodes of severe bilateral subconjunctival hemorrhage. Ocular examination revealed yellowish, marked folding and redundancy of the conjunctiva in the inferior cul-de-sac of each eye.

RESULTS

After two initial conjunctival biopsies that showed only chronic inflammation, a third biopsy revealed the presence of amyloid in the substantia propria of the conjunctiva.

CONCLUSION

Primary localized conjunctival amyloidosis is rare and usually diagnosed histologically instead of clinically. Recurrence of subconjunctival hemorrhage may be the initial presentation. Evaluation for systemic diseases is advised, though the results of the examination are almost always negative.

Three decades of corneal transplantation: indications and patient characteristics

PURPOSE

To review the indications and patient characteristics for penetrating keratoplasty (PKP).

METHODS

Retrospective review of records at the Pathology Service, Department of Ophthalmology, University of Toronto from 1964 to 1997.

RESULTS

The 6,222 records were reviewed. The leading indications for PKP were regraft, keratoconus (KC), pseudophakic bullous keratopathy (PBK), Fuchs' dystrophy, viral infections, and trauma, in that order. During the second half of the 1980s, PBK replaced KC as the leading indication for transplantation. The average age of patients increased from 49 (+/-19) years during the second half of the 1960s to 63 (+/-20) years at the first half of the 1990s. Gender differences (M/F ratio) were significant for KC, viral keratopathy, trauma, PBK, aphakic bullous keratopathy (ABK), edema of unspecified etiology, interstitial keratitis, rheumatoid arthritis, and Fuchs' dystrophy. Diagnostic category differences between all patients for PKPs and regrafts were significant for autoimmune keratolysis, congenital opacities, PBK, ABK, edema of unspecified etiology, scarring, Fuchs' dystrophy, and KC.

CONCLUSION

Indications are in accordance with the literature with the exception of regraft, which was higher. An increase in the average age of patients corresponded with the PBK epidemic. The high male-to-female ratio among patients with KC was different from that previously reported for the prevalence of this condition. Sex distribution among patients with PBK and ABK showed a female predominance. Differences in the underlying disease distributions between regrafted patients and the rest of the series coincide with prognostic classifications for PKP.

Early intraocular pressure after phacoemulsification combined with trabeculectomy

BACKGROUND AND OBJECTIVE

To determine the efficacy of combined phacoemulsification--trabeculectomy in preventing early postoperative increases in intraocular pressure (IOP).

PATIENTS AND METHODS

Eighty patients were enrolled in a prospective cohort study. Thirty-six patients with cataracts and uncontrolled glaucoma underwent combined phacoemulsification--trabeculectomy, and 44 patients with cataracts underwent phacoemulsification alone. The operations were performed in a standardized manner by one surgeon. IOP was measured at 4 hours, 1 day, and 7 days after surgery. The need for intervention (digital massage, medications) and the presence of complications were documented.

RESULTS

Four hours after surgery, 5.5% of patients undergoing the combined procedure had IOPs greater than 30 mm Hg, compared with 22.7% of phacoemulsification patients (P < .05). No significant difference in IOP was found between the groups at postoperative day 1 or day 7.

CONCLUSION

These results suggest that combined phacoemulsification-trabeculectomy protects against early postoperative elevations in IOP. This finding may influence the surgical management of cataracts in patients with poorly controlled glaucoma and significant compromise of visual field or optic nerve.

Morin hydrate: a better protector than purpurogallin of corneal endothelial cell damage induced by xanthine oxidase and SIN-1

PURPOSE

Free radicals are responsible for tissue injury in corneal preservation and transplantation. Morin hydrate, a flavonoid from Brazil wood, has been shown to be cytoprotective in several types of cells. The aim of this study was to investigate the effectiveness of morin hydrate on rabbit corneal endothelial cells against damage induced by oxyradicals and nitric oxide.

METHODS

Corneal endothelial cell cultures were prepared from New Zealand white rabbits, using standard microcarrier technique. Two free-radical-generating systems were used-17 IU/L xanthine oxidase/1 mM hypoxanthine and 5 mM 3-morpholinosydnonimine-N-ethylcarbamide (SIN-1, a nitric oxide-donating agent).

RESULTS

Over 95% of cultured corneal endothelial cells necrosed within 3.6 +/- 1.5 min after exposure to xanthine oxidase/hypoxanthine. Adding morin hydrate delayed cell necrosis to 5.8 +/- 0.3 min (0.25 mM morin hydrate), 13.3 +/- 5.0 min (0.5 mM), and 41.5 +/- 8.6 min (1.0 mM). Exposed to nitric oxide generated by SIN-1, cells necrosed by 9.5 +/- 2.5 min, versus 14.1 +/- 1.3 min (0.25 mM morin hydrate), 27.2 +/- 2.0 min (0.5 mM), and 43.3 +/- 5.4 min (1.0 mM). Morin hydrate significantly prolonged survival of cells compared to equimolar concentrations of purpurogallin, Trolox, or ascorbate (P < 0.01).

CONCLUSION

This study demonstrates that morin hydrate behaves as a broad-spectrum antioxidant: it scavenges not only xanthine oxidase/hypoxanthine-generated oxyradicals, but also nonenzymatic, nitrogen-derived radicals, better than those above mentioned antioxidants. This property of morin hydrate may help prevent free radical damage in corneal preservation solutions.

Utilizing eye bank eyes and keratoplasty techniques to teach phacoemulsification

Learning microsurgery can be a difficult task. Three techniques for practicing phacoemulsification using eye bank eyes, rigid contact lenses, and lamellar keratoplasty are described. These simple methods provide a realistic environment for learning and developing microsurgical skills.

Uveitis-glaucoma-hyphema syndrome after handmade, anterior chamber lens implantation

Two patients developed uveitis-glaucoma-hyphema syndrome secondary to implantation of handmade anterior chamber intraocular lenses (IOLs). The IOLs were designed and made by the patients' ophthalmologists in their native Ukraine. The cases illustrate innovative and unusual solutions to the shortage of quality IOLs in the developing world and the challenging management of patients who present with complications arising from these IOLs.

The prevalence of positive hepatitis B, hepatitis C, and HIV serology in cornea donors prescreened by medical and social history in Ontario, Canada

PURPOSE

To determine the prevalence of hepatitis B (HBV), hepatitis C (HCV), and human immunodeficiency virus (HIV) in the serum of cornea donors who had been previously screened by social and medical history by the Eye Bank of Canada, Ontario Division.

METHOD

A retrospective examination of the donor records of the Eye Bank of Canada, Ontario Division, was conducted. A total of 3,228 records were examined covering the period from May 17, 1993 to May 31, 1996.

RESULTS

The prevalence of HBV was determined to be 0.25%, HCV, 0.93%; and HIV, 0.031%.

CONCLUSION

The data revealed that despite the use of medical and social history to prescreen, a small percentage of prescreened donors test serologically positive. A comparison of the prevalence of HBV, HCV, and HIV in the prescreened cornea donors to a similarly screened cohort of blood donors over a similar time period reveals a higher prevalence in all three diseases in the cohort of cornea donors. An examination of the demographic characteristics of the population as a whole versus the three groups with confirmed serology failed to show a significant difference between the seropositive and seronegative groups. This study confirms the value and necessity of serologic prescreening of cornea donors as is currently the standard of practice.

Endothelial cell analysis of corneas from donor eyes with an intraocular lens: a comparative study

PURPOSE

Many eyes are received from patients who have undergone cataract surgery. Few data document the endothelial cell characteristics in these donor eyes, which have previously been disqualified for transplantation. We compared the endothelial characteristics of the corneas from eyes with intraocular lenses (IOLs) with a group of matching controls.

METHODS

The corneal endothelial characteristics, including cell density, polymegethism, and pleomorphism, were prospectively obtained in 15 corneas from eyes with IOL implants and compared with 17 phakic control eyes.

RESULTS

The mean cell densities (+/-SD) were 2,495 +/- 438 cells/mm2 for the eyes with implants and 2,576 +/- 264 cells/mm2 for the controls. The mean coefficient of variation was 0.307 +/- 0.04 and 0.323 +/- 0.04 for IOL and control group, respectively. No significant difference was found between the two groups (t test, power = 0.97 in detecting a mean difference of 20%).

CONCLUSION

Many eyes with IOLs have endothelial cell densities comparable to those of phakic eyes. A decision to use specific corneas should be made individually based on endothelial cell analysis. Previous ocular surgery may not disqualify a corneal donor.

Pediatric cataract management with variations in surgical technique and aphakic optical correction

PURPOSE

The purpose of the study was to compare the results of three techniques of cataract surgery in children. Two methods included intraocular lens (IOL) implantation and one used contact lens correction of aphakia.

DESIGN

Nonrandomized clinical trial.

PARTICIPANTS

Seventy-seven eyes of 50 children between the ages of 2 1/2 and 16 years who had cataract surgery for the treatment of uncomplicated cataract.

INTERVENTION

Thirty-one eyes underwent a "conventional" style of implantation, and a "phaco-style" of surgery was used in 24 eyes. A contact lens was used as the primary means of aphakic correction in 22 eyes.

MAIN OUTCOME MEASURES

The visual results and complications of each type of surgery were compared.

RESULTS

Corrected visual acuities did not differ significantly between the three groups 6 months after surgery. The incidence and type of complications were significantly different. Better lens centration, less long-term iris changes, or wound-related problems were observed with "phaco-style" modification of the technique of IOL insertion.

CONCLUSIONS

Pediatric IOL insertion eliminated the need for contact lens wear and did not lead to a significantly different corrected visual acuity 6 months after surgery compared with lensectomy with contact lens correction. Adoption of some of the techniques of modern small-incision cataract surgery for pediatric IOL procedures produces a significant reduction in postoperative anterior segment complications compared with a standard limbal approach. Such modifications allow pediatric IOL insertion to be a safe alternative for the correction of pediatric aphakia.

Experimental autoimmune uveitis in HLA-B27 transgenic mice

The major histocompatibility complex (MHC) gene, HLA-B27 is strongly associated with auto-immune uveitis and spondyloarthropathies in humans. Experimental mouse models of autoimmune uveitis involve systemic immunization with the retinal autoantigen interphotoreceptor retinoid binding protein (IRBP). To assess possible roles of HLA-B27 in autoimmune uveitis, as well as to investigate a possible new animal model of human uveitis, inbred strains of C57BL/6 and C57BL/6 possessing the human HLA-B27 or HLA-A2 transgene were immunized with IRBP emulsified in complete Freund's adjuvant (CFA). Dilated eye examinations were performed to assess the timing and clinical course of any ensuing uveitis. Mice were sacrificed 3 to 4 weeks postinjection and the eyes submitted for histopathologic analysis. CFA alone did not produce any clinical uveitis. Fifty percent of eyes from the background C57BL/6 strain developed uveitis as early as 10 days postinjection. Of the eyes demonstrating uveitis, an average clinical score of 2.5 was present. Pathologically, a moderate scleritis and anterior uveitis was present. Fifty percent of A2 transgenic eyes developed uveitis as early as 14 days postinjection with an average clinical score of 2.0. Pathologically, a mild vitritis was present. Uveitis developed in only 20% of B27 transgenic mice and reached a peak on day 28. The average EAU score in diseased animals was 4.5. A dense retinitis and panuveitis was associated with severe vitritis. We conclude that the presence of the B27 gene is associated with a decreased incidence and slower rate of onset of EAU following immunization with IRBP; however, EAU may be more severe in the HLA-B27 expressing animals who do develop disease.

Giant pseudocyst formation associated with chronic corneal edema

A 39-year-old man with a 3-week history of an enlarging mass protruding from his right cornea is presented. Clinical and pathologic findings were compatible with a large corneal pseudocyst. Causes of corneal cyst and pseudocyst formation, as well as a proposed mechanism for the giant pseudocyst formation presented here, are discussed.

Preoperative ultrasound biomicroscopy to assess ease of haptic removal before penetrating keratoplasty combined with lens exchange

PURPOSE

To evaluate a method of assessing anterior chamber intraocular lens (IOL) haptics before combined penetrating keratoplasty and IOL exchange in eyes with poor corneal clarity resulting from pseudophakic bullous keratopathy (PBK).

SETTING

Department of Ophthalmology, Toronto Hospital, Ontario, Canada.

METHODS

Twelve eyes (25 haptics) with PBK were studied using ultrasound biomicroscopy (UBM). The degree of haptic encasement was graded. The result was compared with the degree of difficulty and the complications encountered in removing the IOL at the time of surgery. The surgeons were masked as to the UBM results.

RESULTS

All haptics were easily visualized with UBM, with 23 in the angle and 2 passing through a peripheral iridectomy. On UBM, 9 haptics were noted to lie free in the angle, and 16 were encased by fibrotic tissue. Eight were covered by less than 100 microns and 8 by more than 100 microns of tissue. Calculations using Kappa statistics found a strong predictive value for the UBM in identifying the presence or absence of fibrotic encasement and degree of difficulty in removing the anterior chamber IOL haptics. Ultrasound biomicroscopy also allowed assessment of the adjacent angle for synechias.

CONCLUSION

Ultrasound biomicroscopy provides an alternative method for evaluating anterior chamber IOL haptics when gonioscopy is not possible because of corneal opacity. This method allows the surgeon to predict preoperatively the degree of difficulty that will be encountered in explanting the IOL.

Clinical outcomes following penetrating keratoplasty using the Barron-Hessburg and Hanna corneal trephination systems

Two corneal suction trephination systems currently in use are the Barron-Hessburg and the Hanna trephine. This study assessed the outcome of patients who received penetrating keratoplasty using these two systems. One hundred twenty-four eyes (62 with the Hanna system, 62 with the Barron-Hessburg system) from 98 patients undergoing penetrating keratoplasty were evaluated retrospectively. Best corrected spectacle acuity and corneal astigmatism were assessed 6 and 12 months after surgery. No significant difference was noted between the groups 6 months after surgery. At 12 months, a significant improvement in spectacle acuity was present with 55% of the Hanna group having visual acuity of 20/40 or better compared with 33% of the Barron-Hessburg group (p < 0.005). This difference was greater if eyes having the best visual prognoses were separately evaluated: 74% of the Hanna group had 20/40 vision or better compared with 41% of the Barron-Hessburg group (p < 0.005). In eyes having a good visual prognosis, a significant improvement in visual acuity was present, with 33% of the Hanna group improving nine or more lines compared with 9% of the Barron-Hessburg group (p < 0.05). Postoperative keratometric and refractive astigmatism were not different at 6 or 12 months. We found that visual recovery at 1 year is better using the Hanna system, especially in eyes with good visual prognoses.

In-vitro comparative study of a locally prepared corneal storage medium and Optisol

OBJECTIVE

To compare the in-vitro safety and efficacy of two corneal storage media, Optisol and H-Sol, a chondroitin-sulfate-based medium containing hydrocortisone prepared at the Eye Bank of Canada (Ontario Division).

DESIGN

Twenty paired corneas from human donors (mean age 67.9 years) were randomly assigned for storage in corneal viewing chambers at 4 degrees C in Optisol (10 corneas) or H-Sol (10 corneas). The storage media were masked, and all measurements were done in a blinded fashion.

OUTCOME MEASURES

Corneal clarity and thickness (measured at 0, 2, 4, 8 and 12 days), endothelial cell density and morphology (analysed at days 0 and 12). At day 12 cell viability was determined by staining with trypan blue and alizarin red S, and three randomly selected corneas from either medium were examined by scanning electron microscopy and transmission electron microscopy.

RESULTS

Corneal thickness increased significantly from day 0 to day 12 in both Optisol and H-Sol, and corneal clarity decreased significantly in both media over this period (p < 0.05). At days 2, 4, 8 and 12 the corneas stored in Optisol were significantly thinner than those stored in H-Sol (p < 0.05). There were no significant differences between the media in any of the other indices studied. Endothelial cell density decreased significantly in both Optisol and H-Sol (p < 0.05). There were no within-group differences in percentage of cell loss, coefficient of variation of cell area, figure coefficient or percentage of hexagonal cells.

CONCLUSIONS

The difference in corneal thickness between Optisol and H-Sol may have been due to the higher concentration of chondroitin sulfate in the former (2.5%, compared with 2% in H-Sol) or perhaps to the addition of other components to Optisol that are not present in H-Sol. Efforts continue to improve the formulation of H-Sol. Further studies are necessary to assess its safety and efficacy in vivo.

Perfluorodecalin corneal toxicity: five case reports

Perfluorodecalin is a perfluorocarbon liquid used intraoperatively in retinal detachment repair. It is usually removed at the end of the procedure; however, residual amounts may be retained when poor corneal clarity or intraocular hemorrhage obscures the view. No clinical reports exist on the consequences of retained perfluorodecalin in the anterior segment. We report five cases in which perfluorodecalin was in prolonged contact with the cornea. The period of time for corneal pathology to occur and the role perfluorodecalin played in the etiology of such changes is discussed. A total of 348 patients with retinal detachments in one retinal practice underwent repair using pars plana vitrectomy combined with intraoperative perfluorodecalin between January 1992 and May 1994. Postoperatively, residual perfluorodecalin was observed in the anterior chamber in contact with the corneal endothelium in five patients. The patients were followed clinically for a period of up to 18 months. Four of five patients developed corneal changes from prolonged contact with perfluorodecalin. Corneal edema developed in the area perfluorodecalin-endothelial contact in three of five eyes. The period of perfluorodecalin-endothelial contact before corneal decompensation occurred ranged from 4 to 13 weeks. Two eyes required penetrating keratoplasties for progressive corneal edema. Corneal edema was reversed in one eye after removal of perfluorodecalin from the anterior chamber via multiple paracentesis. One of the remaining eyes developed deep corneal vascularization without edema in the area of perfluorodecalin contact after 12 months. These observations suggest that corneal toxicity may be induced by intraocular perfluorodecalin if it is allowed direct contact with the corneal endothelium for periods as short as 1 month. Some of these changes may be reversible if perfluorodecalin is aspirated from the anterior chamber. Further investigations are required to examine perfluorodecalin-induced corneal toxicity.

Antimetabolite interactions with epidermal growth factor

Antimetabolites such as 5-fluorouracil and mitomycin C are known to delay wound healing. Epidermal growth factor (EGF) has been shown to accelerate corneal epithelial wound healing. This study was designed to investigate the effects of EGF on corneal epithelial healing that has been modified by antimetabolite treatment. New Zealand White rabbits were pretreated with either saline (controls) or 5-fluorouracil (5FU) injected subconjunctivally, or mitomycin C (MMC) applied topically. Circular anterior stromal wounds were created, followed by a 6-hour perfusion of normal saline or 50 micrograms/ml of EGF. Subconjunctival saline or 5FU, or topical MMC treatments were continued after wounding for a total of 6 days. Corneas were photographed and quantitative morphometry of the wound site was performed. Compared with saline controls, MMC significantly delayed wound healing (P < 0.05) whereas 5FU did not (P > 0.05). Compared with 5FU, MMC significantly delayed wound healing with either normal saline or EGF perfusion (P < 0.05). In the presence of either 5FU or MMC, EGF perfusion had no significant effect on the corneal wound-healing rate (P > 0.05). Corneal wound healing is not affected by subconjunctivally injected 5FU while it is delayed by topically applied MMC. EGF treatment does not overcome the inhibitory effects of MMC. EGF therapy may not be useful in the treatment of complications related to antimetabolite therapy.

Pharmacokinetic differences between ocular inserts and eyedrops

Controlled release ocular inserts have been found to increase the amount of drug which is absorbed into the aqueous humour when compared to eyedrops. Systemic absorption following delivery using a controlled release insert has been found to be dependent on the release rate of the insert. The objective of this study was to determine if ocular inserts affect drug absorption into other ocular tissues such as the conjunctiva and iris-ciliary body. Ocular absorption studies were performed using albino rabbits and ethylene-vinyl acetate controlled release devices containing timolol maleate. A compartmental model previously developed to simulate ocular absorption following eyedrop administration was modified and used to simulate these experiments. The conjunctival absorption coefficient calculated by the model and the AUC of the conjunctiva per mumol of delivered drug were found to be 2.7 and 42 times higher, respectively, for the ocular insert as compared to eyedrop administration. The increased conjunctiva absorption was likely the result of reduced tear mixing, which caused a high local concentration of timolol between the insert and the conjunctiva. The AUC of the iris-ciliary body per mumol of delivered drug was found to be 24 times higher for the ocular inserts as compared to eyedrop administration. The AUC of the iris-ciliary body was found to be 1.4 times higher than the AUC of the aqueous humour for eyedrop administration, but 9 times greater for delivery via the ocular inserts. Thus, the increased absorption into the iris-ciliary body and aqueous humour observed for ocular inserts is partially the result of an increase in the amount of drug which enters these tissues via penetration across the conjunctiva and sclera.

Haemophilus aphrophilus bleb infection after a mitomycin trabeculectomy

BACKGROUND

Haemophilus aphrophilus is a rare cause of ocular infection. It has been reported once as a cause of late-onset endophthalmitis in a patient with an inadvertent bleb after cataract surgery. We present a case of Haemophilus aphrophilus bleb infection after a mitomycin trabeculectomy.

METHODS

A 56-year-old woman presented with a bleb infection 10 weeks after a mitomycin C augmented trabeculectomy at a University tertiary referral practice of one of the authors (GET). The causative organism was Haemophilus aphrophilus, identified by the Toronto Public Health Laboratory, Ontario, Canada.

RESULTS

The bleb infection resolved following topical, subconjunctival and intravenous antibiotic therapy. A formal bleb revision was required to repair a persistent bleb leak.

CONCLUSION

Patients who have had trabeculectomies augmented with mitomycin C may be predisposed to bleb infection with unusual organisms. Prompt diagnosis and treatment is necessary to control the infection. Increased awareness and communication with laboratory personnel may increase the isolation of this fastidious organism.

Comparative cytoprotection of cultured corneal endothelial cells by water-soluble antioxidants against free-radical damage

We reported previously that purpurogallin (PPG) markedly protects the cultured rabbit corneal endothelial cells (RCEC) against oxyradical damage generated with hypoxanthine (HX) and xanthine oxidase (XO)(1). In this study, we further compared the cytoprotective activities of PPG versus Trolox (TX, alpha-tocopherol, a water-soluble analogue of vitamin E) and ascorbate (Asc) in confluent cultured RCEC with phase contrast microscopy and confirmed by transmission electron microscopy. PPG prolonged survival of the oxyradical damaged cells longer than those without PPG present (18.6 +/- 1.4 min at 1.0 mM and 11.2 +/- 1.0 at 0.25 mM respectively vs. 7.3 +/- 0.8 min in control). At levels equimolar to PPG, TX, and Asc were less effective in delaying cell necrosis caused by HX and XO (p < 0.01). When exposed to superoxide radicals generated by menadione, RCEC necrosed at 29.8 +/- 1.5 min compared to PPG 47.2 +/- 1.0 min at 1.0 mM and 38.9 +/- 1.0 min at 0.25 mM. This was significantly different from TX and Asc at corresponding concentrations (p < 0.01). PPG scavenges not only HX-XO-generated oxyradicals, but also nonenzymatically produced superoxide radicals, more actively than two well known antioxidants--TX and Asc.

Infectious crystalline keratopathy following trabeculectomy and low-dose topical steroids

A case of infectious crystalline keratopathy in a patient who had undergone trabeculectomy without 5-fluorouracil is described. Chronic low-dose topical steroids were employed. Crystalline keratopathy occurring in this setting has not been previously described. A 73-year-old diabetic women presented with feathery crystal-like corneal infiltrates. These were cultured and treated with antibiotics based on the sensitivities. The cultures showed a nutritional variant of Streptococcus that was difficult to grow on routine culture plates. It was sensitive to vancomycin. Resolution of the infection occurred with topical treatment. Infectious crystalline keratopathy is a rare but classical corneal infection. The microbiological characteristics that give rise to its clinical appearance and laboratory characteristics are discussed. A rationale for diagnosis and treatment is suggested.

A compartmental model for the ocular pharmacokinetics of cyclosporine in rabbits

Studies were conducted in rabbits to determine the ocular distribution and elimination of cyclosporine, with the objective of developing a comprehensive pharmacokinetic model. Following a bolus dose into the anterior chamber, drug levels were measured in the aqueous humor, cornea, iris/ciliary body, lens, sclera, and conjunctiva. Cyclosporine was rapidly eliminated from the aqueous, but drug levels in ocular tissues persisted for in excess of 48 hours, particularly in the cornea and iris/ciliary body. The terminal elimination half life from these tissues was 45 hr and 30 hr, respectively, providing evidence that these tissues could act as a reservoir for the drug. It was found that a compartmental model accurately described the experimental data. A single compartment was used for each of the tissues and fluids sampled, except for the cornea, which was subdivided into two compartments, representing its tissue and aqueous regions.

Depot drug delivery system for 5-fluorouracil after filtration surgery in the rabbit

We investigated the potential value of 50:50 poly (DL glycolic acid-lactic acid) (PGLA) copolymer as a degradable depot delivery system for 5-fluorouracil (5-FU) after filtration surgery. Analysis of retrieved discs after implantation in 22 eyes of 22 pigmented rabbits showed a dual drug release profile and polymer mass loss characteristics. In a second group of pigmented rabbits implantation of PGLA discs impregnated with 5-FU (22 eyes) significantly lengthened the survival time of filtration fistulae compared with discs without 5-FU (18 eyes) or no disc (10 eyes) (p < 0.0001). Use of PGLA copolymer impregnated with 5-FU could prove valuable for patients undergoing glaucoma filtering surgery.

Comparative antioxidant protection of cultured rabbit corneal epithelium

Oxygen-free radicals may injure the epithelium of corneas in storage awaiting transplantation. This study compared the cytoprotective effects of several antioxidants against oxygen-free radical injury to rabbit corneal epithelial cells in vitro. Cultured rabbit corneal epithelial cells were exposed to oxygen-free radicals generated by xanthine oxidase and hypoxanthine. The cytoprotective activities of various antioxidants on this system were compared using established morphologic criteria. The results demonstrated that purpurogallin at 1.0 mM delayed cell necrosis to 9.98 +/- 1.16 min compared with 2.96 +/- 0.67 min without antioxidant protection. This degree of protection was significantly different from that provided by ascorbate (1.0 mM), trolox (1.0 mM), superoxide dismutase + catalase, catalase (92,000 IU/L), mannitol (1.0 mM), and superoxide dismutase (24,200 IU/L) (p < 0.01). We concluded that purpurogallin effectively protects corneal epithelium from oxygen-free radical injury and may help prevent such injury in corneal preservation solutions.

Purpurogallin as a cytoprotector of cultured rabbit corneal endothelium

We examined the protective properties of purpurogallin, a naturally occurring phenol, in delaying necrosis of cultured corneal endothelial cells caused by oxygen free radicals. Endothelial cell cultures were prepared from New Zealand white rabbits using microcarrier cell culture techniques. Corneal endothelial cells were treated with hypoxanthine (2 mM) and xanthine oxidase (67 IU/L) to generate free radicals. The criteria for cell necrosis were cytoplasmic shrinkage, dissolution of plasma membranes and presence of "haloes" around the cells on phase contrast microscopy, confirmed by transmission electron microscopy. More than 95% of second-generation cells exhibited morphologic evidence of necrosis within 4.62 +/- 0.82 minutes after exposure to oxyradicals. The addition of purpurogallin (0.25 or 1.0 mM) significantly increased time to cell necrosis to 8.18 +/- 0.83 and 11.59 +/- 1.71 minutes respectively (p < 0.05). Further studies are under way to determine whether purpurogallin may be useful in preventing endothelial cell damage in corneas preserved for corneal transplantation.

Local efficacy of cyclosporine in corneal transplant therapy

Studies were conducted to evaluate the efficacy of direct injections of cyclosporine (CsA) into the anterior chamber for the prevention of corneal allograft rejection in Dutch Belted rabbits. The mean survival time (MST) of grafts progressively increased from 50 to 89 days as the CsA concentration in the dose was increased from 1 to 10 mg/mL. Injection of 30 microL of 20 mg/mL CsA in olive oil prolonged graft survival to beyond 125 days without any signs of rejection. By comparison, the MST of allografts in control animals which received no therapy was 32 +/- 5 days, and the MST in animals administered a placebo of olive oil only was 31 +/- 4 days. The observed concentration dependence of the MST on CsA concentration is likely related to the time over which the drug delivery rate provides sufficient drug to achieve a therapeutic concentration in the aqueous humor; these studies suggest that the minimum delivery rate to the anterior chamber is between 200 and 325 ng/day. The efficacy of CsA was due to local delivery, and was likely not a systemic effect, because CsA was not detected in the systemic circulation at any time. This indicates that direct delivery of CsA to the eye can be useful in prolonging corneal graft survival, while minimizing systemic side effects. Separate experiments revealed that episodes of advanced rejection could not be reversed by a 30 microL dose of 20 mg/mL CsA to the anterior chamber, indicating the importance of avoiding long periods of subtherapeutic dosing.

Releasable "U" suture for trabeculectomy surgery

Overfiltration after glaucoma surgery can lead to significant complications. Tight suturing of the trabeculectomy flap reduces this problem but can lead to higher pressure and poor drainage of aqueous. Releasable sutures often leave irritating exposed suture ends. We describe a simple two-arm releasable suture technique that leaves no exposed suture ends until one arm of the suture is removed. Good control of postoperative pressure with few complications was achieved in 28 cases using this technique, which allows manipulation at the slit lamp of the trabeculectomy flap, obviating laser lysis of the sutures.

Epikeratophakia for correction of complicated aphakia

We reviewed the cases of 21 patients (22 eyes) who underwent epikeratophakia for aphakia with at least 4 months' follow-up. Thirteen had traumatic cataracts, six had relative contraindications for implantation of an intraocular lens (IOL), one had a dislocated IOL and one had bilateral congenital cataracts. The mean best corrected visual acuity was 20/32.0 (range 20/20 to 20/70) before surgery and 20/38.6 (range 20/20 to 20/70) after surgery. The uncorrected visual acuity improved in all eyes. Twenty eyes (91%) were within two lines of the preoperative best corrected acuity; all eyes were within four lines. Twenty eyes were within 3.0 dioptres of emmetropia postoperatively; all eyes were within 5.0 dioptres of emmetropia. No serious complications were encountered. We conclude that epikeratophakia is a good alternative for the correction of aphakia.

Continuous epidermal growth factor delivery in corneal epithelial wound healing

PURPOSE

To investigate the effects of a single prolonged exposure to recombinant epidermal growth factor on the healing of anterior keratotomy wounds in New Zealand white rabbits.

METHODS

After wounding, eyes were perfused for 1, 2, 4, and 8 hours with either epidermal growth factor solution at a concentration of 50 micrograms/ml or balanced saline solution using a Morgan therapeutic lens (Mortan Inc, Missoula MT) and a syringe pump. Furthermore, concentration response was evaluated by perfusing with epidermal growth factor solutions at concentrations of 5, 50, 100 and 500 micrograms/ml for 4 hours. Wound healing rates were determined by quantitative morphometry of the wound area. The ratio of healing rates of eyes perfused with epidermal growth factor and control eyes provided a measure of the effect of epidermal growth factor on wound healing, and was defined as the epidermal growth factor enhancement factor.

RESULTS

The enhancement factor was found to be 1.04 +/- 0.08, 1.17 +/- 0.07, 1.43 +/- 0.09, and 1.59 +/- 0.07 for perfusion times of 1, 2, 4, and 8 hours, respectively. The concentration response enhancement factors were 0.99 +/- 0.08, 1.43 +/- 0.09, 1.21 +/- 0.09, and 0.95 +/- 0.07 for the 5, 50, 100, and 500 micrograms/ml 4-hour perfusions, respectively.

CONCLUSION

The results indicated that continuous epidermal growth factor exposures of as few as 2 hours produced a significant increase in healing rates (P < 0.05); increasing the time of exposure further increases the rate of wound healing. Results from the concentration response experiments showed that the optimum epidermal growth factor concentration for enhancing epithelial wound healing is approximately 50 micrograms/ml.

Malignant acanthosis nigricans. A case report

PURPOSE

The authors present a case of malignant acanthosis nigricans that has two unusual aspects. The first is involvement of the lid margins with confluent papillomata, causing severe visual impairment, and the second is the association with lung malignancy.

METHODS

A 65-year-old Portuguese man presented with decreased vision, papillomatous lid lesions, pruritus, and progressive thickening of the skin of his face, neck, axillae, and inguinal creases. A diagnosis of acanthosis nigricans was made after skin biopsy. Systemic investigations showed a suprahilar mass, and biopsy was positive for squamous cell carcinoma of the lung.

RESULTS

The patient underwent excision of papillomata from all four lid margins, and this was repeated 1 year later. He also completed a course of palliative radiotherapy.

CONCLUSION

Malignant acanthosis nigricans is rarely associated with lung neoplasms, being more commonly a manifestation of intra-abdominal malignancies. Of note in this case is the extensive ocular involvement and visual impairment.

Continuous flow perfusion of gentamicin with a scleral shell reduces bacterial colony counts in experimental Pseudomonas keratitis

We have previously shown the pharmacokinetic value of delivering gentamicin to the rabbit anterior segment using the Morgan Therapeutic Lens. The present study utilized an intrastromal injection model of Pseudomonas keratitis to test the therapeutic efficacy of continuous flow delivery of gentamicin with the Morgan therapeutic lens. All eyes (n = 52) received an intrastromal injection of approximately 1800 colony forming units (CFU) of Pseudomonas aeruginosa. At 22 hours after injection, eyes were perfused for 6 hours with saline or gentamicin (1, 2.5 or 5 mg/ml), or received gentamicin drops (13.6 mg/ml) at 15 minutes for four doses, then hourly for 6 hours. Corneas were homogenized and plated to determine bacterial survival, and expressed as log colonies (CFU). Log CFU recovered were 7.37 +/- 0.04, 6.64 +/- 0.20, 5.64 +/- 0.31, and 3.56 +/- 0.50 log CFU for saline perfusion, 1, 2.5, 5 mg/ml gentamicin perfusion respectively. Following six hours of treatment with topical fortified gentamicin drops, 5.93 +/- 0.34 log CFU were recovered. Gentamicin perfusion (5 mg/ml) was significantly different from saline or the other treatment groups (P < 0.05). Continuous corneal perfusion with the Morgan Therapeutic Lens demonstrated an increasing dose response curve with increasing perfusate concentration. It was effective in the treatment of experimental Pseudomonas keratitis.

Cyclosporine in the treatment of nonmicrobial inflammatory ophthalmic disease

Eighteen patients with severe, progressive nonmicrobial inflammatory ophthalmic disease (including five with intermediate uveitis, four with sympathetic ophthalmia and three with serpiginous choroiditis) that had not responded to conventional therapy were treated with cyclosporine. Three of the four patients with sympathetic ophthalmia responded quickly and maximally, and the fourth showed partial improvement. One patient, with several corneal graft failures in the right eye, started cyclosporine therapy after undergoing left corneal transplantation; at the last follow-up visit the graft had been clear for almost 3 years. The response was inconsistent in patients with other types of eye disease. In general, the drug was well tolerated; however, two patients stopped treatment because of unpleasant side effects. No serious or irreversible complications developed. The results suggest that cyclosporine therapy is useful in the treatment of sympathetic ophthalmia and in high-risk corneal transplantation.

Toxicity and pharmacokinetics of intravitreally injected ciprofloxacin in rabbit eyes

To assess the toxicity of intraocular injection of ciprofloxacin, 22 New Zealand white rabbits received midvitreal injections of 100, 200, 400, 800 or 3200 micrograms of ciprofloxacin in 0.1 mL of distilled water (39 eyes) or 0.1 mL of distilled water only (5 eyes). The ocular pharmacokinetics of intravitreally injected ciprofloxacin was determined by aqueous humour and vitreous sampling 1, 2, 4, 8, 12, 18 or 24 hours after midvitreal injection of 100 micrograms of the drug in one eye each of 25 New Zealand white rabbits. The samples were analysed by means of a disc diffusion bioassay. No ocular damage was noted on ophthalmoscopy at any of the concentrations tested. Histologic study showed mild, transient vacuolation of the nerve-fibre layer in all eyes, including the control eyes, 2 hours after injection; at 24 hours no vacuolation was evident except at concentrations of 800 and 3200 micrograms, at which plexiform layer damage was evident. Peak aqueous and vitreous levels of ciprofloxacin were obtained at 1 hour (0.59 and 27.26 micrograms/mL respectively); the vitreous level fell to below 1.0 micrograms/mL 12 hours after injection. We conclude that intravitreally injected ciprofloxacin may be a safe and useful antibiotic in the treatment of aminoglycoside-resistant bacterial endophthalmitis.

Collagen shields: efficacy, safety and comfort in the treatment of human traumatic corneal abrasion and effect on vision in healthy eyes

To study the efficacy, safety and comfort of porcine collagen shields in the treatment of traumatic corneal abrasion, patients with corneal abrasions that had occurred within 24 hours before examination were treated with either a collagen shield (18 patients) or tight patching (12 patients). There was no significant difference in the rate of healing or the proportion of corneas healed between the two groups. The collagen shield was significantly more comfortable than the patch (p < 0.05). After 1 hour of wear the collagen shield allowed useful vision (mean 20/100) in nine healthy volunteer subjects. Collagen shields may be of benefit in carefully selected cases of traumatic corneal abrasion.

Familial congenital corneal anaesthesia

Congenital corneal anaesthesia is a cause of severe corneal ulceration and scarring in childhood. Although uncommon, it may be underdiagnosed when present as an isolated entity. Measures such as the use of elbow splints and tarsorrhaphy may be necessary to prevent visual loss. In rare instances, the condition may be inherited. A family is presented with autosomal dominant isolated congenital corneal anaesthesia, and the systemic associations and treatment of the condition are reviewed.