A study which followed participants for over twenty years has found that severe visual impairment is often caused by AMD or age related macular degeneration. The study, which was conducted by Ronald Klein and his colleagues from the University of Wisconsin School of Medicine and Public Health in Madison, has been termed the Beaver Dam Eye Study and has been published in the journal Ophthalmology.
The research began during the 1988 to 1990 period, when 4,926 participants between the ages of 43 and 86 were checked for their visual acuity. Out of these participants, 3,721 returned for a follow up between 1993 and 1995 2,692 participants returned from 1998 to 2000, 2,397 came for the follow up in 2003 to 2005, and 1,913 participants returned in 2008 to 2010. The participants who failed to return for the follow-up were mainly those who had died during the course of the study.
The vision of all the participants was checked during the follow ups. If the best corrected visual acuity in the better eye was found to be less than 20/40 in the better eye when it was 20/40 in both eyes before the study, the participant was said to be suffering from visual impairment. If, during the follow up, the best corrected visual acuity was found to be less than 20/200, the participant was said to be suffering from severe visual impairment.
Macular degeneration was found to be age related
The researchers noticed that none of the participants between the age groups of 50-54 and 60-64 suffered from severe visual impairment. However, 0.2% of the participants in the age bracket of 70-74, 1.6% between 80-84 years, and 6.9% above the age of 85 years were found to be suffering from severe visual impairment. It was observed that the most common cause of visual impairment in these patients was age related macular degeneration.
Age related macular degeneration is the most common cause of severe visual impairment. Therefore, it is essential to monitor the elderly for any signs of visual impairment and to treat it before it leads to complete vision loss.
Ronald Klein, Kristine E. Lee, Ronald E. Gangnon, et al. Incidence of visual impairment over a 20-year period.