THE LATEST RESEARCH

Study Further Defines PDT Complication Rates
A retrospective interventional case series conducted in Switzerland put the incidence of acute severe visual acuity decrease after photodynamic therapy (PDT) with verteporfin (Visudyne) at nearly 3 percent. A total of 485 treatments were delivered to 273 patients with subfoveal choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD) and pathologic myopia. Within seven days of treatment, eight patients (2.9 percent) experienced an acute severe visual acuity decrease of at least four ETDRS lines.

Other complications were infusion-related back or chest pain (2.2 percent), dyspnea and flushing during infusion (0.7 percent), body pain, shortness of breath, and elevated blood pressure (4.8 percent), and general pruritus (2.2 percent), which started four hours after infusion and resolved within 72 hours. No injection site effects, extravasation or photosensitivity reactions were observed. The authors wrote that the results of this study do not change their opinion that the benefits of PDT outweigh the risks.

Source: Schnurrbusch UE, Jochmann C, Einbock W, Wolf S. Complications after photodynamic therapy. Arch Ophthalmol 2005;123(10):1347-50.

Early Retreatment with PDT Provides No Significant Benefit
Retreatment of wet AMD with verteporfin PDT in two-month intervals did not show a significant overall benefit at one year compared with the standard regimen. The primary outcome measure in the prospective, randomized, multicenter clinical trial involving 203 patients with predominantly classic CNV was best-corrected mean ETDRS visual acuity. During the first six months of follow-up, one group of patients was retreated every two months and another group was retreated every three months. From six to 12 months, both groups were retreated every three months. Visual acuity was similar in both groups at baseline.

During the 12 months of follow-up, mean visual acuity was better in the early retreatment group at all intervals, but no statistically significant benefit was seen in the overall population at any time (p>0.1). On the secondary outcome of loss of fewer than three lines of vision, a trend toward better outcomes was observed in the early retreatment group. No statistically significant difference was observed in lesion size for either group throughout follow-up.

Source: Michels S, Wachtlin J, Gamulescu MA, et al. Comparison of early retreatment with the standard regimen in verteporfin therapy of neovascular age-related macular degeneration. Ophthalmology 2005;112(12):2070-2075.

In a 76-year-old man with a 14-week history of blurred vision, a color image shows pigmentary changes, fluorescein angiography shows subretinal neovascularization, and autofluorescence is continuous, which indicates that the retinal pigment epithelium is intact.

Using Autofluorescence Imaging to Better Understand AMD

To describe the autofluorescence characteristics of CNV in patients with AMD, a group of researchers captured 65 images of eyes in various stages of the disease. Twenty images were of recent-onset CNV; eight were of eyes one to six months after diagnosis of CNV; and 37 were late-stage CNV.

They compared the autofluorescence images from the first two groups with fluorescein angiography images. In 16 of 20 cases of early-onset CNV, hyperfluorescence on fluorescein angiography corresponded to areas of normal autofluorescence. Adjacent areas of increased autofluorescence were observed in 13 cases. In 18 of the 20 early-onset images, the main areas of abnormal autofluorescence were larger than the main areas of abnormal fluorescence on angiography. In the second group (one to six months after CNV diagnosis) and the third group (late-stage CNV) areas of decreased autofluorescence corresponded to areas of previous leakage on fundus fluorescein angiography or atrophy.

The researchers noted that the preserved autofluorescence in early-onset CNV indicated viable retinal pigment epithelium initially, which has implications for visual prognosis. They also noted that decreased autofluorescence in the other two groups indicated loss of retinal pigment epithelium and photoreceptors.

Source: Dandekar SS, Jenkins SA, Peto T, et al. Autofluorescence imaging of choroidal neovascularization due to age-related macular degeneration. Arch Ophthalmol 2005;123:1507-1513.

Resistance to Fourth-Generation Fluoroquinolones
To study prophylactic use and bacterial resistance to fourth-generation fluoroquinolone antibiotics in culture-positive cases of acute postoperative endophthalmitis, retinal specialists in New York reviewed two years of cases. Of the 42 eyes with endophthalmitis, 31 (74 percent) were treated prophylactically with fourth-generation fluoroquinolones, and 19 (45 percent) had a positive culture. Five of these organisms were resistant to fourth-generation fluoroquinolones [coagulase-negative staphylococcus (3) and methicillin-resistant staphylococcus aureus (2)]. Resistance to earlier-generation fluoroquinolones was seen in more than half of the cases. No gram-positive organism was resistant to vancomycin. The study authors noted that prophylactic use of fourth-generation fluoroquinolones did not prevent endophthalmitis, and many organisms are resistant to all generations of fluoroquinolone antibiotics.

Source: Acute endophthalmitis in eyes treated prophylactically with 4th generation fluoroquinolone antibiotics, Deramo VA, Lai JC, Fastenberg DM, Udell I, 2005 American Academy of Ophthalmology paper presentation, Chicago, Ill.

Visual Function 10 Years after Scleral Buckling
In 205 eyes that underwent scleral buckling for rhegmatogenous retinal detachment, visual acuity continued to improve over a 10-year period while visual field did not. The retrospective review of the nonconsecutive case series showed that during the first postoperative year (p<0.0001) and the next nine years (p<0.0001) visual acuity increased significantly. Also, between the procedure and one month postoperatively, the area size of visual field (Goldmann perimetry) increased significantly (V-4 isopter, p=0.0001; I-4 isopter, p=0.0001), but the area size of each isopter did not change significantly between one month and 10 years after the procedure.

Source: Mikio S, Yoshikazui I, Yoshikatsu W, Hisashi M, et al. 10-year follow-up of visual functions in patients who underwent scleral buckling. Retina 2005;25(8):965-971.

A recent analysis indicated that the annual rate of malignant transformation (left) of a choroidal nevus (right) in the U.S. white population is one in 8,845.

Estimated Rate of Malignant Transformation of Choroidal Nevi
An analysis of published data suggested that the annual rate of malignant transformation of a choroidal nevus in the U.S. white population is low, one in 8,845. Researchers conducted a literature review and utilized data from the 2000 Census and the Surveillance, Epidemiology, and End Result database (1973-2000). The prevalence of choroidal nevus in the studied population ranged from 4.6 percent to 7.9 percent. The number of individuals with choroidal melanoma in the corresponding age- and race-matched population ranged from 989 to 1,008 (mean 1,002). The results of the analysis are also based on the assumption that all choroidal melanomas arise from pre-existing nevi.

Source: Singh AD, Kalyani P, Topham A. Estimating the Risk of Malignant Transformation of a Choroidal Nevus. Ophthalmology 2005;112(10):1784-9.