Laser photocoagulation for neovascular age-related macular degeneration

Background: Laser photocoagulation was the first treatment introduced to try to halt the progression of neovascular age-related macular degeneration (AMD), in which newly formed vessels or choroidal neovascularisation (CNV) grow under the macula leading to the occurrence of a scotoma or blind spot in the central visual field.

Objectives: The aim of this review was to examine the effects of laser photocoagulation for neovascular AMD.

Search strategy: We searched the CENTRAL, MEDLINE, EMBASE, LILACS, NRR and ZETOC in March 2007.

Selection criteria: We included randomised trials of laser photocoagulation in people with CNV due to AMD.

Data collection and analysis: Two authors independently extracted the data. The risk ratio (RR) of severe visual loss (loss of six or more lines of visual acuity) was estimated at three months and two years after treatment.

Main results: Fifteen trials were included in the review (2064 participants). Three types of photocoagulation were used in the trials: direct photocoagulation of the entire CNV (11 trials), perifoveal photocoagulation (one trial) and grid photocoagulation (three trials). In 12 trials the control group was observation only. One trial compared photocoagulation to submacular surgery and two trials compared different lasers. Data on the progression of visual loss could be extracted from five of the eight trials of direct photocoagulation of the CNV versus observation. The treatment effect was in the direction of harm in all studies at three months follow up (RR 1.41, 95% confidence intervals (CI) 1.08 to 1.82). After two years the treatment effect was in the direction of benefit (RR 0.67, 95% CI 0.53 to 0.83). These studies were clinically heterogeneous with participants having CNV lesions in different locations and different baseline visual acuities. There was little evidence of statistical heterogeneity at three months but substantial statistical heterogeneity at two years. However, all treatment effects in the individual trials were in the direction of benefit. One study comparing perifoveal photocoagulation or observation of subfoveal CNV found benefits that were statistically significant only at two years (RR 0.36, 95% CI 0.18 to 0.72). Other comparisons did not demonstrate differences.

Authors' conclusions: In the medium to long term laser photocoagulation of CNV slows the progression of visual loss in people with neovascular AMD. However, it is associated with an increased risk of visual loss immediately after treatment and this period may be longer in people with subfoveal AMD. With the advent of modern pharmacological therapies, and concern for the impact of iatrogenic scotoma in subfoveal CNV, laser photocoagulation of subfoveal CNV is not recommended. No studies have compared photocoagulation with modern pharmacological agents for AMD for non-subfoveal CNV.