Jorge Zárate

Corneal ectasia after laser in situ keratomileusis

Purpose: To describe 7 patients who developed ectasia following laser in situ kerato‐mileusis (LASIK). Setting: Instituto de la Visión, Buenos Aires, Argentina. Methods: In this retrospective study of 7 patients, visual acuity, refraction, pachymetry, and corneal topography were examined before and after the refractive procedure and the occurrence of ectasia. Results: Two of the 7 patients required penetrating keratoplasty. Ectasia developed within a mean of 1.02 years ± 0.31 (SD). The clinical evolution of ectasia and the potential physiopathogenic causes of ectasia are described. Conclusion: Ectasia should be considered a potential complication of LASIK that is closely related to corneal thickness, but another variable, the optical zone diameter, should also be considered.

Treatment of Acanthamoeba keratitis by corneal cross-linking.

Purpose: To evaluate the efficacy of corneal cross-linking (CXL; riboflavin/ultraviolet A) as a simple therapy for Acanthamoeba keratitis. Methods: Twenty rabbits were systemically anesthetized and the stroma of their right corneas was inoculated with a suspension of Acanthamoeba. Rabbits were divided into 2 groups: one group was treated with corneal CXL 3 days after infection and the other did not receive any treatment (control). All eyes in both groups were examined before (days 0 and 3) and after (day 7) CXL treatment. On day 7, the eyes were enucleated; 18 corneal buttons (9 of each group) were sent for microbiological examination and 2 (1 of each group) for histopathologic examination. Results: All animals developed Acanthamoeba keratitis. There was no statistically significant difference between groups before treatment (day 0, P = 1, and day 3, P = 0.684). The treated corneas had a higher score (3.48 ± 0.30) at the time of enucleation compared with control corneas (2.60 ± 0.26). This difference was statistically significant (P = 0.008). Microbiological analysis revealed that the treated corneas had a higher protozoal count (2.86 ± 0.09) compared with the control corneas (2.18 ± 0.07); this difference was statistically significant (P = 0.001). Conclusions: Treatment of Acanthamoeba keratitis by corneal CXL (riboflavin/ultraviolet A) did not prove effective in decreasing the intensity and severity of Acanthamoeba keratitis.

Malignant Melanoma of the Conjunctiva: Report of a Case

Malignant melanomas of the conjunctiva are extremely rare in children. The authors report an 11-year-old boy who had a nodule at the limbus in a pigmented area since early childhood. The lesion was excised and the diagnosis of atypical compound nevus was made. Five months later, the patient returned with multiple nodules in the bulbar and palpebral conjunctiva. One of the lesions was excised, and the diagnosis was malignant melanoma. He was lost for follow-up for 6 months; then he presented a large pigmented, vascularized mass protruding through the palpebral aperture. Results of systemic workup for metastatic disease were negative, and an exenteration was performed. A few months later, cervical lymphadenopathy developed followed by extensive metastatic disease.

In vitro Differentiation of Adult Adipose Mesenchymal Stem Cells into Retinal Progenitor Cells

Introduction: It has been previously shown that adult mesenchymal stem cells (MSCs) differentiate into neural progenitor cells (NPCs) and that the differentiation process was completed in 24–48 h. In this previous study, MSCs from a bone marrow or fat source were co-incubated with homologous autoaggressive cells (ECs) against nerve tissue, and these NPCs were successfully used in human regenerative therapeutic approaches. The present study was conducted to investigate whether a similar differentiation method could be used to obtain autologous retinal progenitor cells (RPCs). Methods: Human Th1 cells against retinal tissue were obtained by challenging human blood mononuclear cells with an eye lysate of bovine origin; negative selection was performed using a specific immunomagnetic bead cocktail. Fat MSCs were obtained from a human donor through mechanical and enzymatic dissociation of a surgical sample. The ECs and MSCs were co-cultured in a serum-free medium without the addition of cytokines for 0, 24, 48 and 72 h. The plastic adherent cells were morphologically examined using inverted-phase microscopy and characterized by immunofluorescent staining using antibodies against Pax 6, TUBB3, GFAP, Bestrophin 2, RPE 65, OPN1 SW, and rhodopsin antigens. Results: The early signs of MSC differentiation into RPCs were observed at 24 h of co-culture, and the early differentiated retinal linage cells appeared at 72 h (neurons, rods, Müller cells, retinal ganglion cells and retinal pigmented epithelial cells). These changes increased during further culture. Conclusion: The results reported here support the development of a method to obtain a large number of autologous adult RPCs, which could be used to treat different retinopathies.

Study of the lens epithelial cell density in cataractous eyes operated on with extracapsular and intercapsular techniques

ABSTRACT Epithelial cell counting was performed in 47 fragments from lens anterior capsules obtained during extracapsular and intercapsular surgery. Mean cell count was 3,277 cell/mm2; there was no correlation between cell number and age and no significant difference in cell counts between extracapsular and intercapsular surgery. There were, however, significant differences between advanced cataracts and the other cataract types (2,947 vs. 3,356). This may be important in explaining the differences in regenerative opacification of the posterior capsule in the different types of cataracts.

Ciliary body tumor and cataract : Local resection combined with phacoemulsification

&NA; A 57‐year‐old man developed a ciliary body mass, clinically diagnosed as malignant melanoma of the ciliary body, that produced a cataract in the right eye. Treatment was cataract surgery with sclerouvectomy performed simultaneously. Pathohistologic examination revealed an acquired adenoma of the nonpigmented ciliary epithelium. The clinicopathologic features and treatment of this tumor are discussed.

Staining of the Internal Limiting Membrane with the Use of Heavy Brilliant Blue G

Background: Brilliant blue G (BBG) is frequently used in chromovitrectomy to facilitate internal limiting membrane (ILM) peeling. A study was initiated to evaluate if heavy BBG is safe and effective in staining the ILM. Methods: We studied 30 eyes, 23 with idiopathic macular holes and 7 of patients with diabetic macular edema. Removal of the ILMs was assisted by heavy BBG staining. In cases with histopathological correlation the ILMs were evaluated with hematoxylin and eosin, Masson’s trichrome, periodic acid-Schiff and glial fibrillary acidic protein staining. In addition, immunohistochemistry was also performed using specific antibodies for vimentin, neuron-specific enolase, factor VIII and CD68. Using the Image-Pro Plus software of Media Cybernetics Co. we found an average thickness in ILMs. Results: Of the ILM specimens sent, 19/30 (63.33%) could not be processed properly because of the limited sample material, recognizing only fragments of dispersed fibrillar material. In macular hole ILMs we found an average thickness of 1.3 ± 0.65 µm, and in diabetic macular edema ILMs an average thickness of 6.2 ± 1.4 µm. Conclusions: In heavy BBG-assisted ILM peeling we observed no intraoperative or postoperative complications after a mean follow-up of 12 months. Heavy BBG could be an effective and safe vehicle for staining the ILM.

Calibrated needle for ophthalmic fine needle aspiration biopsy

In a great majority of cases, uveal tumours are diagnosed and treated based solely upon clinical examination and ancillary diagnostic studies such as ultrasonography and angiography.1 In general, diagnostic fine needle aspiration biopsy (FNAB) is limited to situations presenting as a diagnostic dilemma such as differentiation between an amelanotic uveal melanoma and a metastatic uveal tumour.2–5 The other major indication for ophthalmic FNAB is for prognostication purposes of uveal melanoma being treated with radiation therapy.6 Most ophthalmic surgeons have used available needles without customisation ranging in size from 22 gauge (G) to 30G, with the 25G needle being the most commonly used.2 ,7 , …

Congenital Glaucoma: Light and Scanning Electron Microscopy of Trabeculectomy Specimens

Until 1968, we treated congenital glaucoma with goniotomy according to Barkan’s technique. With this method, we achieved favorable results in 65 % of the cases (in some after three goniotomies). Since 1969, we consider trabeculotomy according to Harms’ technique the surgical procedure of choice in congenital glaucoma. Our first results were published in 1972 (13). At present we have been able to control the intraocular pressure in 96 % of our cases (120 cases followed from 1 – 9 years).

Episcleral Venous Pressure

We were able to make all these measurements of episcleral venous pressure, thanks to the generosity of our colleague Dr. R. Brubaker of the US Institute of Health who gave us the equipment and showed us how to use it.