Treatment frequency and visual outcome in subfoveal choroidal neovascularization related to pathologic myopia treated with photodynamic therapy

Background: The purpose of this study was to examine the influence of treatment frequency on visual acuity of patients with PDT treatment for subfoveal predominantly classic CNV related to pathological myopia. Design: Retrospective case series. Methods: Thirty-seven patients with subfoveal predominantly classic CNV caused by pathologic myopia and treated with PDT were included. All patients received a full ophthalmic examination, including best-corrected visual acuity, slit-lamp biomicroscopy, fundus photography and fluorescein angiography, before first treatment and every 3 months thereafter. Photodynamic therapy was performed according to standard protocol. Main outcome measurements were visual acuity and treatment frequency. Results: The number of treatments received was 3.35 +/- 1.83 (average: 1-7). In 12 eyes (32.43%); the BCVA was stable or increased during the entire follow-up period. In eight eyes (21.62%), the BCVA decreased and did not return to the baseline values. A transient loss of visual acuity (over 3-9 months) with subsequent improvement in visual function was found in 68% (17 eyes). A gain of three or more lines compared with lowest BCVA was found in 56% (14 eyes). The number of treatments did not correlate with baseline BCVA, greatest linear dimension of CNV at baseline or with the change of BCVA from baseline. In cases with transient worsening of BCVA, the recovery of visual acuity correlated significantly with the number of treatments (r=-0.522, P < 0.05; Spearman rank correlation) received. Conclusions: Visual acuity recovery correlates with the number of PDT re-treatments; in many cases, an improvement in visual function after temporary decrease of BCVA can be observed after re-treatment according to current treatment guidelines. The number of PDT treatments has no negative effect on the visual outcome in subfoveal CNVs caused by pathological myopia.