THE LATEST RESEARCH

Study Implicates a Growth Factor Other than VEGF in Diabetic Retinopathy
Results of a study published in the New England Journal of Medicine indicate that the protein hormone erythropoietin is a potent angiogenic factor that acts independently of vascular endothelial growth factor (VEGF) in proliferative diabetic retinopathy. Researchers measured erythropoietin and VEGF in vitreous fluid samples from 144 patients. The median vitreous levels of both erythropoietin (p<0.001) and VEGF (p<0.001) were significantly higher in the 73 patients with proliferative diabetic retinopathy compared with the levels in 71 patients who did not have diabetes. Based on multivariate logistic-regression analyses, the researchers concluded that erythropoietin was more strongly associated with proliferative diabetic retinopathy than VEGF.

Source: Watanabe D, Suzuma K, Matsui S, et al. Erythropoietin as a retinal angiogenic factor in proliferative diabetic retinopathy. N Engl J Med 2005;353(8):782-792.

Management of Dislocated Foldable IOLs
Outcomes from a consecutive, single-surgeon case series suggest that the widely accepted techniques for managing dislocated PMMA IOLs can also be safely and effectively used to manage dislocated foldable IOLs. In 17 of the 32 cases analyzed, the surgeon repositioned the IOL without scleral suture. In eight cases, he repositioned the IOL with scleral suture, and in seven cases he exchanged the IOL. He exchanged the IOL in all cases where the haptics, by design, were extremely flexible. Mean time from lens dislocation to treatment was 165 days. Other conditions, including but not limited to retinal detachment, age-related macular degeneration, retained lens fragments, and vitreous hemorrhage, were present at the time of presentation in 23 eyes. Mean follow-up after the repair surgery was 9.3 months (50 days to 7.5 years). Visual acuity results and complication rates were similar across all types of IOLs and management approaches. The study author stated that his preferred approach to a dislocated foldable IOL is sulcus fixation without sutures. When sulcus fixation is not possible, scleral suture techniques can be considered, but IOL exchange is a good alternative.

Source: Smiddy WE. Management of dislocated foldable intraocular lenses. Retina 2005;25:576-80.

IVT for CME Secondary to BRVO
Doctors in St. Louis recently reported that intravitreal triamcinolone (IVT) may be useful for treating cystoid macular edema (CME) secondary to branch retinal vein occlusion (BRVO). They reviewed medical records and identified cases in which patients with BRVO and no prior laser therapy were treated with IVT. From among those cases, they identified six in which decreased visual acuity was thought to be mainly due to clinically significant CME and follow-up was at least three months. Mean Snellen visual acuity at the time of IVT treatment was 20/166 (range 20/40 to 6/200). The mean time between BRVO and treatment with IVT was 3.5 months. Three patients required a second injection of IVT, but mean final visual acuity in all eyes after one or two injections improved to 20/106 (range 20/200 to 20/30). All eyes showed improvement in vision, and 83.3 percent improved by two lines or more. Also, in four of the five patients for whom optical coherence tomography (OCT) measurements were available, a decrease in central foveal thickness was noted. One patient required surgical intervention for a significant increase in intraocular pressure.

Source: Lee H, Shah GK. Intravitreal triamcinolone as primary treatment of cystoid macular edema secondary to branch retinal vein occlusion. Retina 2005;25:551-55.

IVT Clears More Quickly from Vitrectomized Eyes
IVT cleared 1.5 times faster from vitrectomized rabbit eyes than it did from nonvitrectomized rabbit eyes, which could be a consideration for planning the treatment in humans, according to a group of researchers. They performed standard pars plana vitrectomy in 42 of 84 eyes. They injected all 84 eyes with 0.1 mL (0.3 mg) of IVT. They obtained every 12 eyes by euthanizing six rabbits one, two, four, seven, 12, 20 or 30 days after the injection. They enucleated the eyes, froze them and used high-performance liquid chromatography and ultraviolet absorbance detection to quantify the amounts of IVT present. After 30 days, triamcinolone was detected in one eye in the vitrectomized group and in four of six eyes in the nonvitrectomized group. Triamcinolone half-life was 1.57 days in the vitrectomized group and 2.89 days in the nonvitrectomized group.

Source: Chin HS, Park, TS, Moon YS, Oh JH. Difference in clearance of intravitreal triamcinolone between vitrectomized and nonvitrectomized eyes. Retina 2005;25(5):556-60.

Clarifying the Role of OCT
Based on their assessment of 131 eyes of 118 patients, researchers in the United Kingdom concluded that compared with fluorescein angiography (FA), OCT is effective for detecting the presence of choroidal neovascularization (CNV), but less accurate for identifying its components. The consecutive series of patients, all suspected of having CNV, underwent OCT and stereo FA imaging. One masked observer examined the OCT images alone and then stereo color photographs as well. Another masked observer examined the angiography images. They found that the sensitivity and specificity of OCT for detecting new, potentially treatable CNV were 96.4 percent and 66.0 percent, respectively. For OCT with stereo images, the sensitivity was 94.0 percent, and the specificity was 89.4 percent. For detecting CNV with a classic component, the sensitivity and specificity of OCT alone were 78.6 percent and 82.7 percent. When OCT and stereo color images were examined together, sensitivity was 82.1 percent, and specificity was 89.3 percent. The researchers stated that OCT at this time cannot replace FA for accurately diagnosing CNV components, but could be a useful tool for prioritizing requests for angiography.

Source: Sandhu SS, Talks SJ. Correlation of optical coherence tomography, with or without additional colour fundus photography, with stereo fundus fluorescein angiography in diagnosing choroidal neovascular membranes. Br J Ophthalmol 2005;89:967-70.