Regular eye exams in elderly help functional vision

May 1, 2006

Outside of the (clinical) trial setting, people behave differentlyand will not necessarily heed advice to obtain an annual exam.

Durham, NC-Elderly people who receive regular eye examinations experience less decline in functional vision, suggest the results of a recent longitudinal analysis.

Researchers found that, on average, each additional year of eye examinations was associated with better visual health and vision-related functioning, said Frank A. Sloan, PhD, the J. Alexander McMahon professor of health policy and management and professor of economics, Duke University, Durham, NC.

Dr. Sloan was one of the authors of a study that was published showing the apparent benefits of regular eye exams (J Am Geriatr Soc 2005;53:1867-1874). He noted that many things happen between screening and an improved outcome that may lead to these results, such as diagnosis and medical or surgical treatment of cataracts and glaucoma, but these factors are not identified or measured in the database used for the study.

Importance of eye exams

One of the implications from this study is the importance of encouraging elderly patients to receive regular eye exams. While general practitioners and internists are perhaps the audience most in need of this message and should use it as additional motivation to refer their patients to eye-care professionals, there is also a message for ophthalmologists, Dr. Sloan said. He explained that they need to work with physicians outside of their specialty to stress the importance of regular eye exams for the elderly and to try to increase the percentage of patients who receive these screenings.

While there are practice guidelines recommending regular eye examinations for individuals with chronic eye diseases, they are often based on evidence from clinical trials. However, outside of the trial setting, people behave differently and will not necessarily heed advice to obtain an annual exam. Elderly patients may have serious illnesses such as heart disease or cancer whose treatment takes precedence over eye care, or the obstacle may be a practical issue such as lack of transportation to a doctor's office.

While there is a need for empirical data, it would be extremely difficult to design and conduct a prospective national longitudinal analysis among the elderly population that would explore the relationship between regular eye exams and changes in self-reported vision, provider codes for vision, and self-reported functional status, such as limitations on activities of daily living.

Data analysis

Therefore, the investigators relied on data from Medicare claims and enrollment, merged with data from the National Long-Term Care Survey (NLTCS), a longitudinal study of people aged 65 and older conducted every 5 years. The investigators analyzed data from 1994 to 1998 and changes in visual and functional status between 1994 and 1999, analyzing a representative sample of the U.S. elderly population that consisted of 14,215 Medicare beneficiaries.

The combined data were used to assess whether regular eye exams were associated with a greater or lesser ability to read a newspaper, the probability of having read during the week before the interview, development of blindness or low vision, and an increase in the number of limitations in instrumental activities of daily living (IADLs) and activities of daily living (ADLs).

ADL limitations include needing help with eating, bathing, toileting, dressing, getting in and out of bed, or getting around inside. Limitations with IADLs consist of needing help with preparing meals, doing laundry, light housework, grocery shopping, keeping track of bills, taking medicine, and making telephone calls.

The investigators had to counter the effects of using observational data, including the possibility that the eye exams were a function of visual status. For example, if people who are having trouble reading or driving are more likely to see a doctor, this complicates the effort to determine causation between the exam and visual and lifestyle outcomes, Dr. Sloan explained. Methodological strategies such as instrumental variables and a statistical technique were used to overcome this problem.

Results of their analysis showed that during the 5 years of follow-up analysis, about 15% of the individuals in the sample developed difficulty with each of the outcome measures except a diagnosis of blindness or low vision, which occurred in only 1.4% of cases.