Laser treatment of drusen to prevent progression to advanced age-related macular degeneration

Maurizio B Parodi, Gianni Virgili, Jennifer R Evans
Cochrane Database of Systematic Reviews 2009, (3): CD006537

BACKGROUND: Drusen are amorphous yellowish deposits beneath the sensory retina. People with drusen, particularly large drusen, are at higher risk of developing age-related macular degeneration (AMD). The most common complication in AMD is choroidal neovascularisation (CNV), the growth of new blood vessels in the centre of the macula. The risk of CNV is higher among patients who are already affected by CNV in one eye.It has been observed clinically that laser photocoagulation of drusen leads to their disappearance and may prevent the occurrence of advanced disease (CNV or geographic atrophy) associated with visual loss.

OBJECTIVES: To examine the effectiveness and adverse effects of laser photocoagulation of drusen in AMD.

SEARCH STRATEGY: We searched CENTRAL, MEDLINE and EMBASE on 14 November 2008.

SELECTION CRITERIA: Randomised controlled trials (RCTs) of laser treatment of drusen in AMD in which laser treatment had been compared with no intervention or sham treatment. Two types of trials were included. Some trials studied one eye of each patient (unilateral studies); other studies recruited patients with bilateral drusen and randomised one eye to photocoagulation or control and the fellow eye to the other group.

DATA COLLECTION AND ANALYSIS: Two review authors independently selected studies and extracted data. We pooled data from unilateral and bilateral studies using a random-effects model. For the bilateral studies, we estimated the within-patient correlation coefficient from one study and assumed it was valid for the others.

MAIN RESULTS: We found nine studies which randomised 2216 people: four unilateral trials, three bilateral trials and two trials that included both a unilateral and a bilateral study arm.Overall, the studies were of moderate quality. Only half of the trials reported adequate allocation sequence generation, allocation concealment and masking of visual acuity outcome assessors.Although two (of the nine) studies reported significant drusen disappearance at two years, photocoagulation did not appear to affect the development of CNV at two years follow up (nine studies, 1767 people followed up, odds ratio (OR) 1.04, 95% CI 0.71 to 1.51) or the loss of three or more lines of visual acuity (six studies, 1628 people followed up, OR 1.17, 95% CI 0.75 to 1.82).

AUTHORS' CONCLUSIONS: The trials included in this review confirm the clinical observation that laser photocoagulation of drusen leads to their disappearance. However, there is no evidence that this subsequently results in a reduction in the risk of developing CNV, geographic atrophy or visual acuity loss.

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