The frontier of genetic testing in ophthalmology, including the availability of a variety of tests to screen for genetic alterations that appear causally related to the development of glaucoma in adults as well as in children, is advancing. The knowledge being developed by the cooperative efforts of researchers and clinicians worldwide in glaucoma genetics is providing new diagnostic and potentially therapeutic opportunities. Judged by the pace of the research it is possible that in the next several years specific defects in a number of “glaucoma genes” will be found that influence the development of elevated intraocular pressure and/or visual field loss. Using the recent findings on the trabecular meshwork glucocorticoid response (TIGR) gene as a paradigm, it is also possible that we may learn mechanisms by which environmental influences and “susceptibility” or “protective” genes can modulate the disease phenotype, potentially through interactions with the gene's promoter. This information could help provide an understanding of clinically observed variations within families of the onset and severity of glaucoma. Studies of how the genetic base is influenced by various “stress” and hormonal factors offer additional prospects to understand changes in homeostatic mechanisms by which the normal physiologic balance in both the front and back of the eye is altered. It is anticipated that the practical value of genetic testing in glaucoma as well as the research opportunities derived from the studies should continue to develop in coming years thereby aiding the clinician in making individual decisions and providing new approaches for defining and treating different forms of glaucoma.