Thoughts From Your Colleagues
I disagree with Dr. Cockerham’s comment in “When It’s Not Glaucoma” (Feature, November) that glaucoma is usually symmetric. The old Duke-Elder series on “simple glaucoma” states, “For one eye can be affected some considerable time before its fellow, it must be concluded that simple glaucoma is essentially a bilateral disease.”1 This asymmetry may be more pronounced in patients with normal-tension glaucoma.1 Cataract, chronic open-angle glaucoma, and age-related macular degeneration are almost always a bit asymmetric and sometimes very asymmetric.
The big question is why are these three major age-related ocular diseases asymmetric? I have always had the suspicion that there is something wrong with the total ocular microcirculation in the eye with the worst disease severity (especially with cataracts). We need a functional metabolic scan of the retina to better understand such diseases. Optical coherence tomography only shows structural changes, which usually occur late in the course of a disease process.
Judson P. Smith, MD
Fort Worth, Texas
1 Drance SM et al. Am J Ophthalmol. 1968;65:891.
Dr. Smith’s concerns are valid: Approximately 25% of patients with open-angle glaucoma have asymmetric disease (i.e., afferent pupillary defect [APD] is present, fields and OCT are dissimilar).1,2 However, 75% or so do have symmetric disease. In this article, the point being made is that when signs are asymmetric—especially if intraocular pressures are symmetric and significant APD is present—symptoms and signs of another cause should be sought as well. One must ask the right questions and look carefully to fully confirm that the problem is truly glaucoma.
Kimberly Cockerham, MD, FACS
1 Schiefer U et al. Br J Ophthalmol. 2012;96(5):629-633.
2 Page CJ et al. J Natl Med Assoc. 1985;77(12):979-984.
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