(RxWiki News) Vision can change depending on the time of day, but it can also change depending on location, according to new research.
A recent study found that older patients both with and without glaucoma had better vision in a clinic setting than at home.
The researchers also found that lighting in the clinic was significantly better than home lighting, and noted that this could explain the difference in vision.
"Choose appropriate lighting for your home."
This study was led by Anjali M. Bhorade, MD, MSCI, of the Department of Ophthalmology and Visual Sciences at Washington University School of Medicine in St. Louis, Missouri. The research team compared vision measured in clinics to vision measured at home and examined factors that could be responsible for any differences seen.
Dr. Bhorade and colleagues analyzed data from 126 patients with glaucoma and 49 patients without glaucoma who were between the ages of 55 and 90 in the Glaucoma and Comprehensive Eye Clinics at Washington University.
Patients were excluded from the study if they had certain types of glaucoma, any other eye conditions, glaucoma suspect status (having risk factors for glaucoma but not yet diagnosed) or ocular hypertension (higher than normal pressure inside the eye).
These researchers recorded the time of day, the length of the visit, the quality of lighting and the weather during the visit.
These researchers measured distant visual acuity (clearness of vision) using Early Treatment Diabetic Retinopathy Study charts. These charts have lines of letters and the letters change in size from line to line. Participants stood a few meters away from these charts and read the letters.
Near visual acuity was measured using Lighthouse Near Visual Acuity card. The card also contained letters that the participants read, but they stood closer to the card.
These researchers also measured visual field for glaucoma patients. Visual field is the total area in which objects can be seen through side vision as the eyes are focused forward.
The visual field for each eye was categorized into a glaucoma stage between 0 and 5 using the Glaucoma Staging System. Stages 0-1 were considered to be mild stages of glaucoma, stages 2-3 were considered moderate, and stages 4-5 were considered advanced.
Several factors were taken into account that could have influenced vision. These factors included age, sex, race/ethnicity, education, occupation and presence of other conditions.
These researchers found that the average scores for the visual acuity tests were significantly higher in the clinic than in the home for all study participants.
For distant visual acuity, 29 percent of participants with glaucoma read two or more lines better in the clinic than at home, and 39 percent with advanced glaucoma read three or more lines better in the clinic than at home.
Of the entire sample, 21 percent read two or more lines better in the clinic than at home for near visual acuity.
These researchers also found that lighting was significantly better in the clinic than it was in participants’ homes.
The authors of this study concluded that poorer vision at home when compared to the clinic was likely a result of poorer home lighting.
"This interesting study shows that visual acuity (ability to resolve detail) in patients with glaucoma is better when tested under the ideal conditions typically encountered during an eye exam than when tested under more "real life" conditions in the patients home. Since acuity is an important marker of visual performance, doctors should be aware of this information in assessing patients' visual disability and when correlating patients' subjective complaints with acuity measured in the office," said Christopher Quinn, OD, optometrist at Omni Eye Service.
This study was published on November 21 in JAMA Ophthalmology.
This research was funded by awards and grants from multiple institutions, including the National Eye Institute, Pfizer, the American Glaucoma Society and Research to Prevent Blindness.
The researchers reported no competing interests.