Prognostic Factors for Visual Outcome and Growth After Photodynamic Therapy for Subfoveal Predominantly Classic Choroidal Neovascularization

Abstract

Purpose: : To identify clinical, angiographic and autofluorescence parameters at baseline that may influence the initial response to photodynamic therapy (PDT) in patients with age–related macular degeneration (AMD) and subfoveal predominantly classic choroidal neovascularization (CNV).

Methods: : 43 consecutive patients (45 eyes) with subfoveal predominantly classic CNV secondary to AMD treated with PDT were included in this study. Demographics, visual acuity measured using the Early Treatment for Diabetic Retinopathy Study (ETDRS) visual acuity charts, fluorescin angiography (FFA) and fundus autofluorescence (AF) images using a Heidelberg Retinal Angiograph (HRA–2) were obtained at baseline and at 3 months following PDT. The total area of the lesion as determined by FFA was measured (mm²) at baseline and at 3 months.The total area of fundus AF abnormality corresponding to the lesion was measured (mm²) and the predominant pattern of AF detected at this site was recorded at baseline. In addition, the background AF pattern outside of the area of the lesion was also recorded. Good visual outcome at 3 months was defined as a loss of less than 15 letters in the ETDRS visual acuity score. Growth of CNV at 3 months was considered whenever the lesion at 3 months had increased in size when compared with baseline measurements as determined by FFA.

Results: : A statistically significant correlation was found between baseline vision and vision at 3 months following PDT (p=0.004), with those eyes having better visual acuity at baseline having higher chance of a good visual outcome at 3 months. Those eyes with growth of the CNV at three months had a higher chance to lose more than 15 letters of ETDRS visual acuity score at 3 months (p=0.041). There was no correlation between the total area of fundus AF abnormality, the pattern of fundus AF found at the site of the lesion, or the pattern of AF present outside the area affected by the lesion(background AF) and the visual outcome at 3 months (p =0.481, p=0.785, p=0.859 respectively) or growth of the lesion at 3 months (p = 0.266, p =1, p = 0.773, respectively).

Conclusions: : Baseline visual acuity and size of the lesion were found to have a statistically significant influence in the initial response to PDT in patients with subfoveal predominantly classic CNV secondary to AMD. Fundus AF abnormalities were not found to be predictive of an initial response to PDT.

Keywords: age-related macular degeneration • photodynamic therapy • visual acuity