Although it has distinctly different characteristics than dry eye or allergic conjunctivitis, there is not a pathological diagnosis in existence for urban conjunctivitis due to ambient pollution, a presenter said here.

"The principal Latin American cities — Santiago in Chile, San Paulo in Brazil, Mexico City in Mexico and Buenos Aires — present with ambient contamination levels higher than those recommended by the World Health Organization," Alejandro Berra, PhD, said at the Argentinean Society of Ophthalmology Annual Course.

He suggested that these pollutants could have a pathologic response in the eye, one that does not fall under allergic or dry eye diagnoses.

Gases such as carbon dioxide, nitrogen and oxygen, metals and particulate materials can be found in the atmosphere, in which the ocular surface comes into contact with 10,000 liters of air per day, he said.

Dr. Berra said there was a correlation between exposure to contaminated ambient gases and changes in the ocular surface in 8,377 patients from Buenos Aires who complained of ocular discomfort and irritation between 2000 and 2006.

In another study, when exposed to one quartile of nitrogen dioxide, 38.5% of patients complained of irritation, but when exposed to four quartiles, 92.9% complained of irritation, he said.

"All of these show that chronic exposure to environmental pollutants of large cities cause symptoms and signs in the ocular surface that can differentiate them from allergic conjunctivitis and dry eye," Dr. Berra said, suggesting that there should be a new classification for urban conjunctivitis due to ambient contamination.

Specifically, he said that irritation, rather than dry eye and itching, showed a statistically significant change. He said that pollution had a unique set of signs and symptoms when compared with dry eye, allergy and toxicity.

Source: The Argentinean Society of Ophthalmology Annual Course

While osteo-odonto-keratoprostheses yielded better anatomical results than osteo-keratoprostheses at 2 years postop, the difference was not statistically significant at 10 years postop, a large chart review found. Conversely, functional results for both techniques were not significantly different at the 2-year follow-up but achieved significant differences at 10 years, the authors noted.

"However, this difference was influenced by the retinal potential and not by the technique itself," the study authors said in the August issue of Graefe's Archive for Clinical and Experimental Ophthalmology .

Rafael I. Barraquer, MD, an OSN Latin America Edition Editorial Board Member, and colleagues analyzed functional and anatomical results for 227 patients who received a keratoprosthesis using tooth and tibial autografts at the Centro de Oftalmología Barraquer in Barcelona , Spain . Specifically, 82 patients received an osteo-keratoprosthesis (group one) and 145 patients received an osteo-odonto-keratoprosthesis (group two). Functional success was defined as a best corrected visual acuity greater than 0.05; anatomical success was defined as retention of the keratoprosthesis lamina.

Mean follow-up time was 3.5 years for group one and 8.4 years for group two.

Based on Kaplan-Meier analyses, 10-year anatomical survival was 66% for patients in group two and 47% for patients in group one.

At 2 years follow-up, functional survival was 63% for patients in group two and 49% for patients in group one; at 10 years, functional survival was 38% for patients in group two and 17% for patients in group one.

Multivariate analysis demonstrated that functional survival was not significantly influenced by either of the surgical techniques, primary diagnosis or age, the authors noted.

"However, a high maximum visual acuity ever reached postop decreased the risk for functional failure," they said.

At 2 years, mean BCVA was 0.33 for patients in group two and 0.28 for patients in group one, according to the study.

Source: Graefe's Archive for Clinical and Experimental Ophthalmology , August 2008

Conjunctival microcysts were found in all hypertensive and glaucomatous eyes in a study, leading researchers to believe that the conjunctiva could be a potential target tissue for in vivo microscopic investigation of glaucoma-induced pathologic modifications.

Marco Ciancaglini, MD, and colleagues at the University of Chieti-Pescara used in vivo confocal microscopy to evaluate conjunctival epithelial characteristics, including mean cell density and the mean area of conjunctival epithelium microcysts, in 30 eyes with untreated ocular hypertension, 96 eyes receiving topical treatment for primary open-angle glaucoma (POAG) and 15 healthy control eyes.

In addition, the researchers evaluated the relationship between IOP and age in hypertensive and glaucomatous eyes. The mean defect of visual fields and therapy time were also assessed in glaucomatous eyes.

The investigators found no evidence of conjunctival microcysts in any of the healthy eyes; however, conjunctival microcysts were found in all eyes with ocular hypertension.

In these hypertensive eyes, microcyst density averaged 19.7 cysts/mm² and total microcyst area averaged 4,063.6 µm², the authors noted.

All eyes with POAG had conjunctival microcysts that averaged 28.7 cysts/mm² in density and 6,564.2 µm² in total microcyst area.

The investigators found no significant differences in microcyst parameters between eyes with ocular hypertension and POAG. In addition, no significant associations were found between either hypertensive or POAG eyes for microcyst density, area, IOP, mean defect of visual fields and the time of therapy, according to the study, published in the July issue of Investigative Ophthalmology & Visual Science .

Source : Investigative Ophthalmology & Visual Science , July 2008

A two-step capsulorrhexis allows for safer preparation for phacoemulsification when approaching a hard cataract, a surgeon said here.

Speaking at the All-India Ophthalmological Society session at the Argentinean Society of Ophthalmology Annual Course, Arup Chakrabarti , MS , showed a technique that he devised.

"The most difficult situation in these cataracts is the capsulorrhexis. There is hardly any visibility," he said. "Once the capsulorrhexis in a white cataract situation is done, half the job is done. Subsequently, the surgery should go on extremely well."

With the advent of various dyes, Dr. Chakrabarti said this process has become easier

The first step, Dr. Chakrabarti said, is to perform a small 3-mm to 4-mm capsulorrhexis to allow for its natural move toward the periphery. This allows for easy retrieval for the surgeon, he explained.

"If you feel this rhexis size is not adequate for you to get good phacoemulsification in a hard cataract ... we can perform a two-step rhexis," he said.

In the creation of the second capsulorrhexis, Dr. Chakrabarti showed that he decompresses the capsular bag, removes as much material as possible and re-inflates the bag before performing an additional capsulorrhexis to the necessary size and shape.

"If there is pressure and the cataract is swollen, then I think it is not safe to make a one-step rhexis," he said. "If I try to make a 5-mm rhexis in a cataract that is really swollen, I am taking a lot of risk. If I tend to go to the periphery ... it's very difficult to get it back to the center, whereas if I'm making a 3-mm rhexis, it can tend toward the periphery and still it is in the safe zone."

Source : Argentinean Society of Ophthalmology Annual Course July 2008

Retinal pigment epithelial cells appear to preferentially accumulate the xanthophylls lutein and zeaxanthin over beta-carotene by a process that is dependent on the protein SR-BI, according to a study.

"These data provide new mechanistic information about the preferential accumulation of the xanthophylls in the human eye and strongly suggest the participation of the transporter SR-BI," the study authors said. "Further investigations will be necessary to confirm this suggestion, since the human ARPE-19 cells may not fully recapitulate the properties of the RPE in vivo."

In order to examine the mechanisms through which carotenoids accumulate in RPE cells, Alexandrine During, PhD, and colleagues compared cellular uptakes after introducing lutein, zeaxanthin and beta-carotene into the human RPE cell line ARPE-19.

Once the ARPE-19 cells had fully differentiated, the investigators found that the RPE cells had absorbed approximately twice as much of the xanthophylls lutein and zeaxanthin than beta-carotene ( P < .05).

At 9 weeks, cellular uptakes were 1.6% for beta-carotene, 2.5% for lutein and 3.2% for zeaxanthin, they noted.

When using specific, targeted antibodies against the lipid transporters cluster determinant 36 (CD36) and scavenger receptor class B type I (SR-BI), RPE cellular uptake of beta-carotene and zeaxanthin was significantly decreased by between 40% and 60% in the presence of anti-SR-BI but not with anti-CD36.

In addition, the investigators found that using small interfering RNA against SR-BI yielded a 90% inhibition of SR-BI protein expression, which resulted in a 51% reduction in beta-carotene and an 87% reduction in zeaxanthin, according to the study, published in the August issue of Journal of Lipid Research .

Source: Journal of Lipid Research , August 2008.