The Effect of Argon Laser Trabeculoplasty on the Visual Field of Patients with Glaucoma

Abstract

Argon laser tarabeculoplasty (ALT) was performed on 232 eyes of 168 patients. Indication for treatment was progression of visual field loss due to glaucoma, despite maximum tolerated medical treatment. Mean percentage IOP change was -21.6% (± 19); mean F.U. was 9 months (3–21). Visual field were obtained with an Octopus computerized perimeter, using programs 31 or 32. Quantitative analysis of functional results was done only on eyes without significant amount of false answers or visual acuity changes or pupil size changes. 113 eyes met these requirements. IOP variations secondary to ALT were similar to those observed in the total group of treated eyes. Mean F.U. was 10 months (4–21). A visual field change was considered significant when a 15% variation of the mean quadrantic sensitivity was observed and the initial mean sensitivity was greater than 10 dB. When initial mean sensitivity was less than lOdB a 40% change was required to be considered significant. In our sample visual fields improved in 17% of patients, remained unchanged in 55% and worsened in 28%. Although visual field changes and IOP changes did not overlap always as expected there is a good correspondence between hydro dynamic and functional success. Patients with less advanced disease were more likely to have good functional results. The last decades have witnessed much debate regarding how, when, and, even, whether elevated intraocular pressure is responsible for glaucomatous optic nerve damage. Traditionally, treatment has largely been based on lowering intraocular pressure to a level which will no longer compromise an eye. Since the report of Wise and Witter argon laser trabeculoplasty (ALT) has been used successfully to decrease intraocular pressure in patient affected by primary open angle glaucoma (POAG) (7–10). The long-term effect of ALT on the natural history of glaucomatous disease, that is, on the functional visual ability of patients with POAG is, however, not established. We report here information regarding the course of visual field changes in patients undergoing ALT. The data are analyzed to determine possible relationships between change in IOP and change in the visual field.