Epidemiologic trends observed in study of disparities in eye disease

May 4, 2009

Several major epidemiologic trends are apparent in the study of disparities in eye diseases. One decades-long trend has been a steady shift from infectious to chronic sources of disease and mortality. The leading causes of blindness and visual impairment worldwide are cataract and glaucoma, whereas trachoma, once the second-leading cause, now is further down the list, said Debra A. Schaumberg, ScD, OD, MPH, associate professor, Department of Epidemiology, Harvard School of Public Health, Boston.

Fort Lauderdale, FL-Several major epidemiologic trends are apparent in the study of disparities in eye diseases. One decades-long trend has been a steady shift from infectious to chronic sources of disease and mortality. The leading causes of blindness and visual impairment worldwide are cataract and glaucoma, whereas trachoma, once the second-leading cause, now is further down the list, said Debra A. Schaumberg, ScD, OD, MPH, associate professor, Department of Epidemiology, Harvard School of Public Health, Boston.

The transition from infectious to chronic conditions in eye disease, however, seems to be lagging behind that of other major diseases, such as cancers and coronary heart disease, added Dr. Schaumberg, who also is associate epidemiologist, Division of Preventive Medicine, Brigham and Women’s Hospital, Boston.

Studies have uncovered numerous disparities in eye diseases, including gaps between and within ethnic and racial groups, males and females, developed and economically developing countries, and age groups. These disparities are complex and involve an interaction among such factors as behavior, biology, discrimination, environment, a shortage of health-care professionals, and socioeconomic issues, including access to health care, she added.

The expanding body of information on the prevalence of various eye diseases among various subgroups has led to greater understanding of these diseases and to identification of lifestyle factors that could influence the risk of disease development.

A theory called compressed morbidity hypothesizes that healthy lifestyles could reduce and compress disability into a shorter period toward the end of life, Dr. Schaumberg said. Annual declines in morbidity rates in developing countries for the past two decades suggest that this theory is valid, although younger age groups are more likely to have risk factors such as obesity or smoking.

Disparities, however, are apparent in this general trend toward improved health, she said. In developing countries, there has been no evidence of a decrease in morbidity overall or in eye disease.

“In fact, all the indications are that the opposite is occurring,” Dr. Schaumberg said. “Chronic diseases are occurring at earlier ages, and routine secondary types of prevention, including eye surgery, are not widely available.”

Data do not yet indicate any compression of eye disease morbidity, but there is hope since eye disease trends tend to lag behind those for overall health.

“Maybe we just haven’t gotten there yet,” Dr. Schaumberg concluded.