[show abstract][hide abstract] ABSTRACT: 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.
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.
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.
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.
British Journal of Ophthalmology 02/2002; 86(1):62-9. · 2.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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).
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.
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.
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.
[show abstract][hide abstract] ABSTRACT: 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.
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).
Of the 29 corneas from seropositive donors, HCV RNA was detected in 7 (24.1%).
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.
[show abstract][hide abstract] ABSTRACT: 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.
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.
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.
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.
Journal of Glaucoma 07/2000; 9(3):268-72. · 1.87 Impact Factor
[show abstract][hide abstract] ABSTRACT: To report the ocular presentation and histopathology of a patient with primary localized conjunctival amyloidosis.
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.
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.
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.
American Journal of Ophthalmology 03/2000; 129(2):245-7. · 3.63 Impact Factor
[show abstract][hide abstract] ABSTRACT: To review the indications and patient characteristics for penetrating keratoplasty (PKP).
Retrospective review of records at the Pathology Service, Department of Ophthalmology, University of Toronto from 1964 to 1997.
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.
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.
[show abstract][hide abstract] ABSTRACT: To determine the efficacy of combined phacoemulsification--trabeculectomy in preventing early postoperative increases in intraocular pressure (IOP).
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.
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.
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.
Ophthalmic surgery and lasers 04/1998; 29(4):273-9.
[show abstract][hide abstract] ABSTRACT: 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.
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).
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).
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.
Current Eye Research 02/1998; 17(2):149-52. · 1.71 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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.
Ophthalmic surgery and lasers 12/1997; 28(11):957-60.
[show abstract][hide abstract] ABSTRACT: 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.
Journal of Cataract and Refractive Surgery 12/1997; 23(9):1414-7. · 2.53 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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.
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.
The prevalence of HBV was determined to be 0.25%, HCV, 0.93%; and HIV, 0.031%.
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.
[show abstract][hide abstract] ABSTRACT: 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.
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.
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%).
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.
[show abstract][hide abstract] ABSTRACT: To examine the effects of EGF, delivered from a semi-solid drug delivery system, on corneal epithelial wound healing following anterior keratectomy wound creation in the eyes of New Zealand white rabbits.
A semi-solid drug delivery system based on a Carbopol gel was developed. Following creation of a 7.5 mm circular anterior keratectomy wound, 50 microL of either a placebo gel or an EGF-containing gel, was instilled in the inferior fornix. The gel remained in the eye for 8 hours, at which time it was removed. Anaesthesia was maintained for the entire 8-hour period. Wound healing was evaluated by quantitative morphometry. We evaluated 0.04, 0.1, 0.2, 0.4, and 1% EGF concentrations in the gel. Tear EGF concentrations and histology of the healing corneas were also examined.
The enhancement factor (ratio of the healing rate with the EGF gel and control gel) was 1.13 +/- 0.12, 1.40 +/- 0.14, 1.29 +/- 0.12, 1.80 +/- 0.22, and 1.09 +/- 0.12 for the gels containing 0.04, 0.1, 0.2, 0.4, and 1% EGF by mass, respectively. The increases in the rate of wound healing were significant with the 0.1, 0.2 and 0.4% gel formulations. Histologically, the 0.4% gels resulted in cellular hyperplasia after 5 days of healing. Differences between the placebo gel-treated and EGF-containing gel-treated eyes were evaluated at both 2 and 5 days. The concentration of EGF in the tears during the treatment period was approximately constant for both the 1% and 0.04% gels. The average tear concentration during the instillation period was 2.87 +/- 0.36 micrograms/mL and 200.61 ng/mL +/- 116.10 for the 1% and 0.04% gels respectively.
Treatment with EGF in a Carbopol gel carrier for a period of 8 hours results in significant wound healing enhancement (p < 0.05). The optimum EGF loading in the gel was determined to be 0.4%. A slow release gel may be an effective way to deliver EGF to the corneal surface.
Current Eye Research 04/1997; 16(3):183-90. · 1.71 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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).
Department of Ophthalmology, Toronto Hospital, Ontario, Canada.
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.
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.
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.
Journal of Cataract and Refractive Surgery 04/1997; 23(2):239-43. · 2.53 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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.
[show abstract][hide abstract] ABSTRACT: 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.
[show abstract][hide abstract] ABSTRACT: 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).
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.
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.
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.
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.
Canadian Journal of Ophthalmology 09/1996; 31(5):221-7. · 1.15 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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.