Nonpreserved human amniotic membrane transplantation for conjunctival reconstruction after excision of extensive ocular surface neoplasia.

PURPOSE: To report our experience on the use of nonpreserved human amniotic membrane transplantation (AMT) in ocular surface reconstruction after excision of extensive ocular surface neoplasia (OSN). DESIGN: Prospective noncomparative interventional case series. PARTICIPANTS: In all, 10 eyes of 10 consecutive patients with extensive OSN involving various areas of limbus, conjunctiva, and cornea (conjunctival carcinoma in situ, four eyes; squamous cell carcinoma, three eyes; malignant melanoma, two eyes; conjunctival-orbital lymphangioma, one eye) were included in this prospective noncomparative interventional case series. After excision of the neoplasia with 3-4 mm tumour-free margins, double freeze-thaw cryotherapy was applied to the margins of the remaining conjunctiva, and nonpreserved human amniotic membrane graft was sutured to the adjacent conjunctiva using 8/0 vicryl sutures and cornea using 10/0 nylon sutures, with the epithelial side facing up to cover the bare sclera and cornea. Postoperatively, topical corticosteroids were used for 3 months. RESULTS: After tumour excision and AMT, a satisfactory result with a wet, stable conjunctiva, and rapid and complete healing was observed in all eyes. Over a mean follow-up of 10.0 months (range, 6-27 months), all but one eye remained free of tumour recurrence. In one eye with conjunctival melanoma, there was a small recurrence, which was treated with excision and cryotherapy. Treatment complications were partial stem cell deficiency in two eyes and symblepharon formation in one eye. Immune graft rejection was not encountered. CONCLUSION: Nonpreserved human AMT appears to be useful for reconstruction of ocular surface following excision of extensive OSN.

The evaluation of normal corneal topography in emmetropic eyes with computer-assisted videokeratography.

PURPOSE: By defining the topographic features of normal corneas, corneal surface abnormalities and their relation to visual function may be better understood. In our study, we have defined the corneal topographic features of emmetropic eyes to evaluate the relationship between topographic patterns and visual acuity. METHODS: Topographic pattern of 114 normal corneas of 114 emmetropic subjects with a keratometric astigmatism of 0.5 D or less were analyzed by computer-assisted videokeratography. Thetopographic maps were grouped into the following patterns: round, oval, symmetric bow tie, asymmetric bow tie, and irregular. RESULTS: Asymmetric bow tie was the most common topographic pattern in our study population (33%), followed by symmetric bow tie (29%), round (14%), irregular (12%), and oval (11%) patterns. There were significant differences in the astigmatic values obtained by keratometry versus videokeratography for aspheric patterns, while the values among the spheric patterns were more in agreement. Mean corneal astigmatism calculated from videokeratographic data was 0.24 D for round, 0.61 D for oval, 1.05 D for symmetric bow tie, 0.85 D for asymmetric bow tie, and 0.76 D for irregular patterns. CONCLUSION: We conclude that: the topographic configuration may not be a good predictor of visual function; an emmetropic eye may have an aspheric topographic pattern, such as asymmetric or symmetric bow tie; and the reconstruction algorithm used for providing topographic maps may not be accurate enough to determine the true shape of the corneal surface for interpretation.

Conjunctival impression cytology in patients wearing contact lenses.

PURPOSE: Evaluation of contact lens-induced cytologic changes on the conjunctival surface. METHODS: Fifty eyes of 25 patients wearing soft or rigid gas-permeable contact lenses, and 50 healthy eyes of 25 control subjects were examined with conjunctival impression cytology. Of the patients wearing contact lenses, 40% did not have any contact lens-related complaints, whereas 60% had some minor complaints related to contact lens intolerance. The material obtained by impression cytology was examined with regard to epithelial cell morphology, goblet cell density, and snake-like nuclear chromatin changes. RESULTS: When epithelial cell morphology was graded according to the system described by Nelson, specimens from the control group revealed 90% of the eyes to be grade 0 and 10% to be grade 1, whereas of the eyes wearing contact lenses, 8% were grade 0, 36% grade 1, 32% grade 2, and 24% grade 3. Thus statistically significant differences were observed between the control group and the contact lens group with regard to each grade (p < 0.05) as well as to the goblet cell densities (p < 0.05). Snake-like chromatin changes, on the other hand, were observed in 30 and 27% of the eyes wearing soft and rigid gas-permeable contact lenses, respectively, whereas these were not encountered in any eye in the control group. CONCLUSION: Epithelial changes were noted to be more frequent and more severe in symptomatic patients than in those without any complaints. No correlation was found between average duration of contact lens wear and the risk of contact lens intolerance or development of squamous metaplasia.

The use of rigid gas permeable contact lenses in scarred corneas.

Perforating corneal injuries often result in scarred corneas in which adequate visual rehabilitation cannot be achieved with spectacles due to irregular corneal surface. In these eyes, the presence of aphakia often adds to the problem with the coexistence of anisometropia. In this study, rigid gas permeable (RGP) contact lenses were fit in 33 post-traumatic scarred corneas of 33 patients. Twenty-seven of the 33 eyes (82%) were successfully fit without complications for an average follow-up of 19.3 months. The success rate was observed to be lower (50%) for patients less than 10 years old, whereas it was 100% in patients older than 20 years. The six failures included two eyes with amblyopia and unsatisfactory visual acuity, two eyes in two patients who lacked motivation to use contact lenses, and two eyes that were contact lens intolerant. There was no significant correlation between the failure groups and the location and size of the corneal scar. The only contact lens related complication was punctate epithelial keratitis in three of the 33 eyes (9%). The results of this study indicate that RGP contact lenses are successful in the majority of patients (82%) with post-traumatic scarred corneas, especially in the adult age group, and may obviate corneal surgery in these patients.

Penetration of cyclosporin A into the rabbit cornea and aqueous humor after topical drop and collagen shield administration.

We used commercially available 12-hour collagen shields to deliver cyclosporin A (CsA) to the cornea and aqueous humor in rabbit eyes. Six New Zealand white rabbits were divided into three groups. The first group (four eyes) received 6 mg of CsA in castor oil and the second group (four eyes) received 6 mg of CsA in olive oil applied as topical drops to rabbit eyes within 12 hours. In the third group (four eyes) 12-hour collagen shields soaked in 6 mg CsA in olive oil were applied to rabbit eyes. The amount of CsA in corneal and aqueous samples from eyes treated with CsA castor oil and CsA olive oil were compared with each other and with collagen shield treated eyes. CsA concentrations were measured by radioimmunoassay. After the total dose of 6 mg CsA, percentage penetration was measured as follows: CsA castor oil--0.51% in aqueous and 20.75% in cornea; CsA olive oil--0.17% in aqueous and 11.13% in cornea; and with collagen shields--0.44% in aqueous and 11.84% in cornea. These results show that the CsA levels of castor oil drops were higher than those obtained with olive oil drops. In eyes with collagen shields, CsA levels were higher than olive oil drops but nearly equal to the castor oil drops. Collagen shields may be useful as an ocular delivery system for CsA.

Contamination in contact lens care systems.

We studied the rate of contamination in the contact lens care systems and conjunctivas of 30 asymptomatic cosmetic soft contact lens wearers. In caring for their lenses, 23 patients used chemical disinfection systems (quaternary ammonium solutions), six patients used hydrogen peroxide, and one used heat. Eighteen patients used unpreserved intravenous saline solution, and only seven patients used commercially prepared preserved saline solutions. Cultures were obtained from lens cases, lens care solutions, and conjunctivas. Contamination was found in 70% of the lens care systems. Fifty-seven percent of the patients had lens case contamination, and 17% had conjunctival contamination. The most frequently isolated bacteria in the lens care systems were Pseudomonas, Staphylococcus epidermidis, and Escherichia coli. We suggest the development of more effective systems for disinfection.