Synopsis of Studies:

A maxim in glaucoma therapy for as long as any of us can remember is that lowering the intra-ocular pressure slows the progression of optic nerve progression. In the 1990’s, the consensus opinion and standard of care dictated intraocular pressure lowering even though formal studies have never been done. At this time, there was concern that third party payers might not pay for glaucoma treatments in the absence of scientific data confirming IOP lowering improved glaucoma outcomes.

In response of this challenge, a series of randomized studies was organized in the 1990’s. This alphabet soup includes: AGIS, CIGTS, OTHS, CNTGT, and EMGT. The result of these studies confirmed that IOP reduction is effective in slowing the progression of POAG.

A brief synopsis of some of the studies:

OHTS – Ocular Hypertension Treatment Study: After 5 years, 10% of control (no medication) patients developed glaucoma as compared to only 5% of treated patients. Optic nerve cupping changes in this study were found to be the most sensitive way to monitor for progression. The risk of untreated ocular hypertension patient developing glaucoma thus is about 1% per year.

EMGT – Early Manifest Glaucoma Trial: On the average, IOP was reduced by 5.1 mm Hg 25%. Risk of progression decreased about 10% with each mm of HG reduction. Patients treated in the EMGT had ½ the progression risk of control patients. In this study of high and normal tension glaucoma patients, it was found that visual field deterioration and the optic disk hemorrhages were the most sensitive signs of glaucomatous progression (as opposed to cupping changes).

AEGIS – Advanced Glaucoma Intervention Study: Whereas in the OHTS and EMGT studies the pressure-lowering goal was 25%, in these advance patients, we should lower the pressure more aggressively. To achieve these lower pressure ( 12.0 mm of Hf or so) filtering surgery must be considered as option if medications and laser treatments are ineffective.

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