Researchers from Johns Hopkins and the National Institute on Aging have presented evidence that older Americans with age-related macular degeneration tend not to travel as far from home as older adults with unimpaired vision. This was not the case, however, among the study subjects with glaucoma, even though both conditions cause vision loss which generally makes travel more difficult.
The research, entitled Alteration of Travel Patterns with Vision Loss from Glaucoma and Macular Degeneration, was published in the November 2013 issue of JAMA Ophthalmology (formerly Archives of Ophthalmology). JAMA Ophthalmology is an international peer-reviewed journal published monthly by the American Medical Association.
The authors are Frank C. Curriero, PhD; Jessie Pinchoff, MPH; Suzanne W. van Landingham, MD; Luigi Ferrucci, MD, PhD; David S. Friedman, MD, PhD; and Pradeep Y. Ramulu, MD, who represent the following institutions: Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland; Wilmer Eye Institute, Johns Hopkins School of Medicine; and the National Institute on Aging, National Institutes of Health.
About the Research
From Macular degeneration tied to staying closer to home via Reuters Health:
Older Americans with macular degeneration tend not to travel as far from home as others with [unimpaired], according to a new study. However, that was not the case among people with glaucoma, even though both conditions cause vision loss which could make traveling more difficult, researchers said.
Previous studies established that people with age-related macular degeneration (AMD) stop or restrict their driving, but not necessarily that they travel less, according to lead author Frank Curriero of the Johns Hopkins Bloomberg School of Public Health in Baltimore.
“This study uses global positioning systems to demonstrate that when AMD patients do go outside their homes, that they don’t go as far away from home as compared to individuals with [unimpaired] vision, and tend to live a more constricted life. We didn’t think AMD and glaucoma would have different outcomes, so that was unexpected,” he said.
Age-related macular degeneration damages sharp detail and central vision [i.e., visual acuity], which is important for reading and driving. Glaucoma damages the eye’s optic nerve and often lead to the slow loss of peripheral vision [i.e., visual field loss].
The average daily excursion, or maximum distance from home, was 5.6 miles for people with macular degeneration, 6.3 miles for people with glaucoma and 6.9 miles for those without vision loss.
For people with macular degeneration, every line they had to move up on an eye chart due to vision loss was tied to a quarter-mile decrease in the farthest distance traveled from home. However, that association was not as clear among people with glaucoma or in the comparison group.
Lines on an Eye Chart and Vision Loss
Visual acuity is a number that indicates the sharpness or clarity of vision. In the United States, the Snellen Eye Chart is a test that is commonly used by eye care professionals to measure a person’s distance visual acuity. It contains rows of letters, numbers, or symbols printed in standardized graded sizes.
To test your eyes, your eye doctor will ask you to read or identify each line or row at a fixed distance (usually 20 feet), although a 10-foot testing distance is also used.
- If you can read line 8 (directly above the red bar) from 20 feet away while wearing your regular glasses or contact lenses, the doctor records your vision (or visual acuity) as 20/20 with best correction.
- If the smallest print you can read is line 3 (T, O, Z) from 20 feet away while wearing your regular glasses or contact lenses, the doctor records your vision (or visual acuity) as 20/70 with best correction.
- If you can only read the big “E” on line 1 of the chart from 20 feet away while wearing your regular glasses or contact lenses, the doctor records your vision (or visual acuity) as 20/200 with best correction.
More about the Study from JAMA Ophthalmology
From the article abstract:
Objective: To determine whether decreased visual acuity from age-related macular degeneration (AMD) and visual field loss from glaucoma are associated with restricted travel patterns in older adults.
Setting: Patients were recruited from an eye clinic, while travel patterns were recorded during their real-world routines using a cellular tracking device.
Participants: Sixty-one control subjects with normal vision, 84 subjects with glaucoma with bilateral [i.e., both eyes] visual field loss, and 65 subjects with AMD with bilateral or severe unilateral [i.e., one eye] loss of visual acuity had their location tracked every 15 minutes between 7 am and 11 pm for 7 days using a tracking device.
Results: [For] subjects with AMD and control subjects, average excursion size decreased by approximately one-quarter mile for each line of better-eye visual acuity loss. Similar but not statistically significant associations were observed … for visual field loss in subjects with glaucoma and control subjects. Being married or living with someone and younger age were associated with more distant travel, while less-distant travel was noted for older individuals, African Americans, and those living in more densely populated regions.
Conclusions: Age-related macular degeneration–related loss of visual acuity, but not glaucoma-related loss of visual field, is associated with restriction of travel to more nearby locations. This constriction of life space may impact quality of life and restrict access to services.