Krypton laser photocoagulation for idiopathic neovascular lesions. Results of a randomized clinical trial. Macular Photocoagulation Study Group
The Idiopathic Neovascularization Study--Krypton Laser is a multicenter
randomized controlled clinical trial conducted to determine whether krypton
red laser photocoagulation is useful in preventing or delaying loss of
visual acuity in eyes that have either choroidal neovascularization 1 to
199 microns from the center of the foveal avascular zone or choroidal
neovascularization 200 microns or farther from the foveal avascular zone
center with associated blood and/or blocked fluorescence extending within
200 microns of the foveal avascular zone center in the absence of any other
clinically significant eye disease. Eligible lesions could have blood or
blocked fluorescence that extended through the entire avascular zone.
Patients were assigned to laser photocoagulation (n = 24) or to observation
only (n = 25). With 65% of these patients followed up for 5 years and 85%
for 3 years, there is evidence that krypton laser treatment is beneficial.
After 3 years of follow-up, 2 (10%) of 20 treated eyes in comparison with 7
(37%) of 19 untreated eyes had lost six or more lines of visual acuity (P =
.15). Furthermore, more untreated eyes than treated eyes had experienced
such losses at each point in follow-up after the 3-month examination. The
findings from this trial taken with findings of other trials conducted by
the same investigators for lesions similar in appearance and location but
secondary either to age-related macular degeneration or to ocular
histoplasmosis support the conclusion that patients with idiopathic
parafoveal neovascularization benefit from laser treatment.
