In treating glaucoma, don’t forget old-fashioned clinical skill
The cover story in the current issue of Ocular Surgery News focuses on the progression of glaucoma, one of our field’s most perplexing mysteries. The longer I practice ophthalmology, the less certain I have become that we really understand glaucoma. Sure, I can follow accepted standards of care, setting target pressures and assessing regularly for compliance and efficacy, but I feel less and less like we really know what’s going on, especially with the enigmas we call low-tension glaucoma and ocular hypertension.
New technologies such as high-resolution optical coherence tomography scans give us reason for hope, offering unprecedented analysis of the functional unit of vision that is affected by glaucoma — the optic nerve and its associated fiber layer. Clearly, this powerful tool has a place along with visual field testing to help gauge the progression of this disease. But let’s not forget the most valuable tool we possess — a careful visual optic nerve examination, comparing to well-done previous photographs.
Let’s face it, visual field testing is a very limited technology. After all, the test is performed by a machine, but the test is not performed on a machine. The patient taking a field test is prone toward making all sorts of errors. Additionally, as cataracts progress year by year, general sensitivity declines, and this can exaggerate focal field defects. Don’t forget about dry eye, a condition that increases with age and also reduces the reliability of this test.
Optic nerve OCT scanning also has its failings, with interference coming from media opacity and the limitations of the technician performing the test.
Let’s remember that the capable brain of a practitioner, combined with time spent doing a careful examination, is the best tool we have for helping prevent progression of one of the most challenging diseases we treat.