A study from University of Toronto researchers extends earlier findings of potential adverse effects of ophthalmic preservatives on surgical outcomes, showing that increased preoperative exposure to ophthalmic solutions preserved with benzalkonium chloride is a risk for earlier trabeculectomy failure, independent of the number of medications used.

A retrospective chart review selected 128 patients who had undergone a trabeculectomy between 2004 and 2006. The number and type of ophthalmic drops used preoperatively and relevant demographics were recorded. Surgical failure criteria included inadequate pressure lowering or need for postoperative ocular antihypertensives, laser trabeculoplasty, 5-fluorouracil needling or repeated surgery. Patients were examined for these criteria over a minimum postoperative period of two years. Data were assessed using Kaplan-Meier and Cox regression models.

Complete surgical success was achieved in 47.7 percent of the patients. Patients received between one and eight BAK-containing drops daily, with a median of three. Time to surgical failure in patients receiving higher preoperative daily doses of BAK was shorter than in patients who had less BAK exposure (p=0.008). Proportional hazard modeling identified uveitic and neovascular glaucoma as significant confounders of the univariate model (p=0.024), although the main effect of BAK exposure was maintained, with a hazard ratio of 1.21 (p=0.032). The number of different medications used to control intraocular pressure did not significantly affect survival time in a secondary Cox model (p=0.948).
J Glaucoma 2013;22:730-735.
Boimer C, Birt C.

Endophthalmitis Associated With Intravitreal Injections
A retrospective review of patients who underwent intravitreal injections in two different settings, office-based and operating room, between January 2009 and December 2011 indicates that the rate of clinically suspected endophthalmitis after intravitreal injection is low whether the procedure is performed in the office or operating room setting.

A total of 11,710 intravitreal injections were performed by two physicians during the study period. Group A (n=8,647) underwent intravitreal injection in the examination room in an office-based setting. The intravitreal injections performed included ranibizumab (n=2,041), bevacizumab (n=6,169) and triamcinolone acetonide (437). Diagnoses included neovascular age-related macular degeneration (n=5,376), diabetic macular edema (n=1,587), retinal vein occlusion (n=1,068) and miscellaneous diagnosis (n=616). Group B (n=3,063) underwent intravitreal injection in the operating room. There were 683 ranibizumab injections, 2,364 bevacizumab injections and 16 triamcinolone injections. Diagnoses included neovascular AMD (n=1,936), DME (n=771), RVO (n=189) and miscellaneous (n=267). There were five cases (0.043 percent) of clinically suspected endophthalmitis in the 11,710 injections. Three cases (0.035 percent) occurred in Group A and two cases (0.065 percent) occurred in group B.
Retina 2014;34:18-23.
Tabandeb H, Boscia F, Sborgia A, Cirací L, et al.

Differences in Iris Thickness Among Ethnic Groups
California researchers evaluating the capability of iris thickness parameters to explain the difference in primary angle-closure glaucoma among different ethnic groups suggest that groups with historically higher prevalence of PACG (Chinese Americans) possess thicker irides than other measured groups.

In this prospective study, 259 patients with open angles and 177 patients with narrow angles from five different ethnicities (African American, Caucasian American, Hispanic American, Chinese American and Filipino American) that met the inclusion criteria were consecutively recruited from the University of California, San Francisco, general ophthalmology and glaucoma clinics to receive anterior segment optical coherence tomography imaging under standardized dark conditions. Images from 11 patients were removed due to poor visibility of the scleral spurs, and the remaining images were analyzed using the Zhongshan Angle Assessment Program to assess the following measurements for the nasal and temporal angle of the anterior chamber: iris thickness at 750 and 2,000 μm from the scleral spurs and the maximum iris thickness at the middle one-third of the iris.

In comparing iris parameters among the open-angle ethnic groups, significant differences were found for nasal iris thickness at 750 and 2,000 μm from the scleral spurs in which Chinese Americans displayed the highest mean value (p=0.01; p<0.0001). Among the narrow-angle ethnic groups, significant difference was found for nasal iris thickness at 2,000 μm from the scleral spurs, in which Chinese Americans showed the highest mean value (p<0.0001). A significant difference was also found for temporal maximum iris thickness at the middle one-third of the iris, with African Americans exhibiting the highest mean value (p=0.021). Iris thickness was modeled as a function of angle status using linear mixed-effects regression, adjusting for age, sex, pupil diameter, spherical equivalent, ethnicity and the use of both eyes in patients. The iris thickness difference between the narrow-angle and open-angle groups was significant (p=0.0007).
J Glaucoma 2013;22:673-678.
Lee R, Huang G, Porco T, Chen Y, et al.

Femtosecond Laser-Assisted Cataract Surgery Has a Learning Curve, But is Safe and Efficient

Researchers from the department of ophthalmology at Semmelweis University analyzed the intraoperative complications of the first 100 femtosecond laser-assisted cataract surgeries, as well as possible complications of femtosecond capsulotomies. The researchers determined that while there is a learning curve, with cautious surgical technique these complications can be avoided, and the femtosecond laser-assisted method is safe and efficient for cataract surgery.
A retrospective analysis discovered the following complications: suction break (2 percent); conjunctival redness or hemorrhage (34 percent); capsule tags and bridges (20 percent); anterior tear (4 percent); miosis (32 percent); and endothelial damage due to a cut within the endothelial layer (3 percent). There were no cases of capsule blockage or posterior capsule tear. During the learning curve, there were no complications that would require vitrectomy.
J Cataract Refract Surg 2014;40:20-28.
Nagy Z, Takacs A, Filkorn T, Kránitz K, et al.