Abstract
Abstract: :
Purpose:To report the data of existing literature on the natural history of occult choroidal neovascularization (O-CNV) in patients with age related macular degeneration (AMD). Methods:MEDLINE database was used as primary data source. Search was conducted using the textword "occult choroidal neovascularization" to identify studies reporting information on vision loss and disease progression in symptomatic patients with O-CNV as defined by fluorescein angiography and observed for at least 1 year. Results:Among 122 articles, 8 potentially relevant reports were identified: 4 were randomized clinical trials (RCTs) and 4 were observational case series (OCS). RCTs: (#1) among 26 eyes of patients with decreased vision and O-CNV assigned to observation by the MPS Group in the AMD Study Krypton Laser, 41% and 70% lost 6 or more lines at 1 and 5 years, respectively, and 46% developed classic CNV (C-CNV) at 1 year (MPS Study group, 1996); (#2) 62% and 52% of 40 eyes with subfoveal O-CNV in patients assigned to observation in a pilot trial evaluating grid laser treatment of O-CNV deteriorated 2 or more lines and developed C-CNV at 1 year, respectively (Stevens, 1997); (#3) 49.2% of 59 patients with O-CNV assigned to observation in the Radiation Therapy for Neovascular AMD (RAD) Study lost 3 or more lines at 1 year (RAD Study Group, 1999); (#4) 68% and 47% of 92 patients with O-CNV assigned to placebo in the Verteporfin in Photodynamic Therapy (VIP) trial, lost 3 and 6 or more lines, respectively at 2 years; 49% of these patients developed C-CNV at 2 years (VIP report nr. 2, 2001). OCS: (#1) 47% of 68 patients whose data were retrospectively reviewed and with a follow-up of over 1 year lost 6 or more lines and 61% progressed to disciform scar at the most recent examination (Bressler, 1988); (#2) 40% of 82 patients with a mean follow up of 3 years lost 6 or more lines and 29% developed classic CNV (Soubrane, 1990); (#3) among few eyes which were followed for over 1 year from a large series of patients with O-CNV studied and classified in subgroups with indocyanine green angiography (ICGA), 40% to 67% lost 2 or more lines at 1 year, depending on the ICGA pattern (Guyer, 1996); (#4) in 55 patients with well-defined plaque CNV on ICGA initial and final median visual acuity were 20/50 and 20/100, respectively (Pece, 2000). Conclusion:Although some studies have shown that occult CNV has a more variable and benign course than C-CNV, many eyes with O-CNV in symptomatic patients have a significant chance of developing severe visual acuity loss and C-CNV after 1 year of observation. New treatment modalities are needed to reduce the risk of severe vision loss in these patients.
Keywords: 346 choroid: neovascularization • 308 age-related macular degeneration • 352 clinical (human) or epidemiologic studies: natural history