The influence of treatment extent on the visual acuity of eyes treated with Krypton laser for juxtafoveal choroidal neovascularization. Macular Photocoagulation Study Group
PURPOSE: To examine the direct relationship between the extent of treatment
with krypton red laser photocoagulation and visual acuity loss in eyes with
choroidal neovascularization secondary to ocular histoplasmosis or
age-related macular degeneration. PATIENTS AND METHODS: Photographic and
visual acuity records from 129 eyes treated in the Ocular Histoplasmosis
Study--Krypton Laser and 224 eyes treated in the Age-Related Macular
Degeneration Study--Krypton Laser were reviewed. The proportion of eyes
with severe visual acuity loss (6 or more lines of loss) was examined for
subgroups of eyes based on the distance of the neovascular lesion from the
center of the foveal avascular zone and on the extent of laser treatment to
the lesion. Differences in the proportions with severe visual acuity loss
were evaluated by longitudinal data analysis methods. RESULTS: Among eyes
in the Ocular Histoplasmosis Study--Krypton Laser with lesions less than
200 microns from the center of the foveal avascular zone, only 5% of eyes
with laser treatment that covered the foveal side and had a narrow (< or
= 100 microns) border of treatment to adjacent uninvolved retina
experienced severe visual acuity loss compared with approximately 25% of
eyes with either some of the foveal side of the lesion left untreated or a
wide border of treatment on the foveal side. Treatment extent had little
influence on severe visual acuity loss in eyes in the Ocular Histoplasmosis
Study--Krypton Laser with neovascular lesions 200 to 500 microns from the
center of the foveal avascular zone or in eyes in the Age-Related Macular
Degeneration Study--Krypton Laser with lesions in either distance category.
CONCLUSIONS: Accurate, complete treatment of choroidal neovascularization
close to the foveal center is required to provide the patient with the best
chance of avoiding further severe visual acuity loss, especially in
patients with ocular histoplasmosis. Even among experienced retinal
specialists, the required accuracy of treatment is difficult to achieve.
