ABSTRACT
A number of retinal disorders preferentially involve the macula or have distinct macular characteristics. Electrophysiologically, the multifocal ERG provides topographical information and is a useful objective measure of macular function. Although the focal ERG can also assess macular dysfunction, the popularity and availability of focal ERG are diminished with advances in multifocal ERG. An isolated macular lesion is unlikely to reduce the overall ERG response enough to affect the full-field ERG, but in some ‘‘macular’’ conditions such as cone dystrophy and X-linked retinoschisis, the fullfield ERG is still needed diagnostically to determine diffuse retinal abnormalities. The pattern ERG is dominated by macular-related activity but provides no topographical information. Likewise, the VEP is dominated by activity from the central visual field but an impaired VEP may be produced by a deficit anywhere along the visual pathway including the retina, optic nerve, and brain. This chapter discusses the utility of electrophysiologic tests in diseases that may be categorized as ‘‘macular disorders.’’ The conditions covered are:
Age-related macular degeneration Macular degeneration-autosomal dominant, recessive Central serous chorioretinopathy Doyne honeycomb retinal dystrophy=malattia leven-
tinese Stargardt macular dystrophy-fundus flavimaculatus Best vitelliform macular dystrophy Cone dystrophy Central cone dystrophy (occult macular dystrophy) Peripheral cone dystrophy Cone dystrophy with supernormal and delayed rod
ERG (supernormal and delayed rod ERG syndrome) Sorsby fundus dystrophy Pattern dystrophy X-linked retinochisis Central areolar choroidal dystrophy North Carolina macular dystrophy (central areolar
pigment epithelial dystrophy) Progressive bifocal chorioretinal atrophy Fenestrated sheen macular dystrophy Familial internal limiting membrane dystrophy
AGE-RELATED MACULAR DEGENERATION
Age-related macular degeneration (AMD), also known as agerelated maculopathy or senile macular degeneration, is one of the leading causes of blindness. Age-related macular degeneration usually affects persons over age 50 years and the incidence increases with age. Age-related macular degeneration is more prevalent among Caucasians than among blacks. Both environmental and genetic factors are involved in the pathogenesis of AMD. Clinical features include macular drusen, pigmentary changes, and geographic atrophy of the retinal pigment epithelium and choriocapillaris. In addition, the disease may progress with further loss of central vision from neovascular maculopathy characterized by choroidal neovascularization, serous or hemorrhagic detachment of the
subretinal and fibrovascular proliferation with scar formation. The diagnosis of AMD is based on clinical examination with the aid of angiography to assess neovascularization. Treatments include high-dose oral antioxidant, vitamin, and mineral supplementation, focal laser photocoagulation, and photodynamic therapy involving systemic administration of a photosensitizing drug followed by nonthermal laser application.
