Treatment of macular subretinal neovascularization with the red-light krypton laser in presumed ocular histoplasmosis syndrome

Treatment of recurrent juxtafoveal subretinal neovascular membranes with krypton red laser photocoagulation

Thirty-seven eyes initially treated with argon blue-green, argon green, or krypton red laser photocoagulation demonstrated a recurrent subretinal neovascular membrane (SRNVM) at the edge of the treatment scar extending into the foveal avascular zone and were retreated with krypton red laser photocoagulation. The subretinal neovascular membrane was due to the presumed ocular histoplasmosis syndrome (POHS) in 10 eyes, aging macular choroidal degeneration (AMCD) in 22 eyes, and miscellaneous causes in five eyes. Anatomic success, defined as complete obliteration of the recurrent SRNVM, was achieved in 26 eyes (70%). When compared to pretreatment visual acuities, 23 of 37 eyes (62.2%) had stable or improved postoperative visual acuities during the follow-up period. Twenty-six eyes were retreated one time; nine eyes required two retreatments; and two eyes required three retreatments. Final visual results showed visual acuity greater than or equal to 20/40 in 7 eyes (18.9%); visual acuity greater than or equal to 20/80 in 16 eyes (43.8%); visual acuity greater than or equal to 20/100 in 19 eyes (51.4%); visual acuity greater than or equal to 20/200 in 27 eyes (73%); and visual acuity greater than or equal to 20/400 in 34 eyes (91.9%).

Ocular effects of various laser wavelengths

Lasers have become an indispensable tool in management of many ocular disorders. This review describes the principles of lasers and the effects various laser modalities and wavelength modalities can produce on ocular structure. Guidelines are provided for appropriate selection of various wavelengths and prevention of complications of the laser treatment.

Macular photocoagulation. Optimal wavelength selection

Relative merits of different laser wavelengths for macular photocoagulation are analyzed in terms of light scattering and light absorption in hemoglobin, melanin, and macular xanthophyll. Disadvantages of inner retinal damage in the macula caused by the blue-green argon photocoagulators in standard clinical use are discussed, along with advantages of argon green and krypton yellow light. Results of treatment of subretinal neovascularization in disciform macular degeneration are presented. A repetitive treatment, close follow-up protocol was employed with the objectives of closing neovasculature and preserving central visual field. In 74 successive patients treated with monochromatic argon green radiation, neovasculature was closed in 93%, central visual field loss was reduced or stabilized in 76%, and visual acuity was improved or stabilized in 70%. Results were analyzed in terms of location and size of the neovascular membrane, and it was found that best results were obtained with neovascularization farther than 600 microns from the foveola and smaller than 2 mm2. In 17 patients with neovascular membranes more than 600 microns from the foveola, neovasculature was closed in 100%, central visual field loss was reduced or stabilized in 94%, and visual acuity was improved or stabilized in 88%. Similar results were obtained with monochromatic krypton yellow radiation.