The natural history of occult choroidal neovascularisation associated with age-related macular degeneration. A systematic review.

INTRODUCTION: The purpose of this review is to combine the results of existing literature on the natural history of occult choroidal neovascularisation (CNV) associated with age-related macular degeneration (AMD).
MATERIALS AND METHODS: Published reports evaluating eyes with occult CNV in AMD patients were selected for meta-analysis based on a computerised MEDLINE search. Pooled estimates of the proportions of eyes with a vision loss greater than 2 to 3 (moderate vision loss) or 6 lines (severe vision loss) at 1 year and 2 to 3 years, respectively, or developing a classic component on fluorescein angiography at 1 year were measured.
RESULTS: There is no significant heterogeneity among published rates of visual loss and development of classic CNV. The overall pooled estimates (95% confidence limits) of the proportions of eyes with at least moderate or severe vision loss, respectively, were 59% (53% to 64.5%) and 34% (25% to 43%) at 1 year and 70% (64% to 76%) and 47% (40% to 54%) at 2 to 3 years; the overall pooled estimate of the percentage of eyes developing classic CNV at 1 year was 46% (39% to 54%).
CONCLUSION: A substantial number of patients with occult CNV from AMD will develop at least moderate visual loss at 1 year and severe visual loss within 3 years. However, visual acuity may remain stable in up to 30% of patients. These results may help us to understand the exact role of new therapies and in planning future trials.