Role of argon laser trabeculoplasty as primary and secondary therapy in open angle glaucoma in Indian patients. (Scientific Correspondence).

Aims: To study the efficacy of argon laser trabeculoplasty (ALT) as a primary and secondary therapy in Indian patients with primary open angle glaucoma (POAG).

Methods: ALT was performed as a primary therapy in 40 eyes of 21 patients newly diagnosed with POAG (group I) and as a secondary therapy in 39 eyes of 21 patients who had been taking topical antiglaucoma medications for more than 1 year. The best corrected visual acuity, baseline intraocular pressure (IOP), diurnal variation of IOP, anterior chamber angles, and visual fields were the various parameters evaluated before and after performing ALT. Follow up visits were scheduled at 24 hours, 1 week, 1 month, 3 months, 6 months, and 1 year after the surgery. The patients were recalled at the end of 5 years for the final follow up examination. Success of ALT was defined as IOP [less than or equal to]21 mm Hg without any medication with no progression of disc or visual field changes.

Results: The prelaser mean IOP was 25.8 (SD 3.4) mm Hg in group I and 26.1 (3.2) mm Hg in group II. The mean post-laser IOP at 5 year follow up was 18.1 (3.2) mm Hg in group I and 22.7 (3.9) mm Hg in group II (p= 0.002) while the mean reduction in IOP was 5.7 (1.8) mm Hg in group I and 3.2 (0.8) mm Hg in group II (p<0.001). The diurnal variation reduced from a preoperative value of 7.9 (1.4) mm Hg to 3.6 (1.3) mm Hg in group I and from 7.7 (1.4) mm Hg to 5.8 (1.8) mm Hg in group II (p<0.001). The success rate of ALT was 75% at 1 year and 65% at 5 years in group I and 35% at 1 year and 10% at 5 years in group II.

Conclusion: ALT can be used as a primary therapy in pigmented eyes with POAG. ALT is less effective as a secondary therapy in controlling the IOP in eyes of patients on long term topical antiglaucoma treatment.

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The initial treatment of primary open angle glaucoma (POAG) has been the reduction of intraocular pressure (IOP), by using topical medications. If medical therapy fails, then the patient is generally subjected to surgery. The introduction of argon laser trabeculoplasty (ALT) enabled glaucoma specialists to interpose an intermediate treatment between medical therapy and surgery to lower the IOP and postpone/obviate the need for filtering surgery. Several investigators have shown that ALT as a primary treatment may be more efficacious than topical antiglaucoma therapy in reducing the IOP and may help glaucoma patients enjoy a better quality of life by reducing the inconvenience and side effects of ocular hypotensive medications. (1-3)

Although the efficacy of ALT has been established in white populations, (4-8) there are very few studies to suggest the role of ALT as a primary therapy for eyes with dark brown irides. (9) In the present study, we evaluated the role of ALT as a primary therapy and also as an adjunctive secondary procedure in POAG patients on topical antiglaucoma medications.

MATERIAL AND METHODS

Consecutive patients definitively diagnosed to have POAG at the glaucoma service were enrolled for the study over a period of 6 months. The criteria for patient selection were age [less than or equal to]50 years, phakic eyes, cup:disc ratio of 0.5 or more, polar notching or narrowing of the neuroretinal rim, and asymmetry …