to the editor: The article on the visually impaired patient by Drs. Rosenberg and Sperazza is an important review of eye disease for the family physician. However, the article contains some omissions.
The authors correctly state that visual acuity using a standard Snellen chart should be used to assess all patients for visual impairment. However, this test has to be performed under standard conditions so that inconsistency in acuity measurements does not lead to inappropriate clinical decision making. The two critical variables are the distance between the patient and the chart, and the illumination of the chart. The distance should be permanently marked so that it cannot be erased, and the patient should be placed directly behind that mark. The chart can be illuminated by directing a spotlight at it.1
The section of their article on age-related macular degeneration (ARMD) is not current. The authors state, “if neovascularization develops [in patients with nonexudative ARMD], retinal laser therapy has proved to be useful”; they add, “photodynamic therapy and intravitreal injections of antivascular endothelial growth factor and corticosteroids have shown promise in treating subsets of patients with macular degeneration.” Photodynamic therapy has been superseded by antivascular endothelial growth factor antibodies such as ranibizumab (Lucentis) and bevacizumab (Avastin), which have been shown to be superior in clinical trials; these are now the treatment of choice for exudative (“wet”) ARMD.2,3 Rapid referral to an ophthalmologist for intraocular injection of one of these agents is essential because undue delay could lead to irreversible loss of vision in the affected eye.
The authors state that “glaucoma causes increased ocular pressure that can damage the ganglion cell layer of the retina and cause visual loss.” Raised intraocular pressure is only one risk factor for the development of glaucoma, a condition that has a multifactorial etiology. Glaucoma is characterized by gradual progressive loss of the retinal ganglion cell nerve fiber layer that then manifests as visual field loss and may eventually cause total irreversible blindness in the affected eye.4
editor's note: This letter was sent to the authors of “The Visually Impaired Patient,” who declined to reply.