The phenotype of age-related macular disease provides information about the genes that confer risk and the environmental factors that are involved in risk in a particular individual.

May 2 - Fort Lauderdale, FL - The phenotype of age-related macular disease provides information about the genes that confer risk and the environmental factors that are involved in risk in a particular individual.

"It has been thought for a long time that both inheritance and environment play a role in the pathogenesis of disease," said Alan Bird of the Moorfields Eye Hospital, London. "There is a great deal of evidence for genetic predisposition to age-related macular degeneration (AMD) from many twin and sibling studies. An individual will develop AMD disease if they have appropriate genetic risk factors and appropriate environmental pressures."

At the annual meeting of the Association for Research in Vision and Ophthalmology, Dr. Bird stated that there are qualitative differences in phenotype between late and early age-related macular degeneration (AMD), and particularly in early disease. He and his colleagues found solid concordance in phenotype between the two eyes of an individual in many of the qualitative attributes of early age-related maculopathy, that is, the density, the number, and the size of drusen, which do not fluoresce.

In a study of late AMD, most eyes had great concordance between lesions bilaterally, but this was not absolute. In a small percentage of eyes, geographic atrophy caused visual acuity bilaterally. In the United Kingdom, this occurs in 20% to 25% of patients with AMD. However, in Iceland, for example, this occurs in 80% of patients, which may reflect that the environment plays a role.

He also noted that the phenotypic characterization produces purer samples of disease, which should aid genetic and epidemiological research. Phenotype also may lead to concepts of pathogenesis.