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Changes in retinal thickness linked to visual acuity in patients with retinitis pigmentosa
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Retinal thinning and thickening, due to cell loss and presumed edema respectively, may be associated with lower visual acuity in patients who have retinitis pigmentosa, according to a study.
Michael A. Sandberg and colleagues at the Massachusetts Eye and Ear Infirmary performed the study to determine if visual acuity could be linked to the changes in retinal thickness in patients with retinitis pigmentosa.
The study included 162 patients who had typical retinitis pigmentosa with visual acuities of 20/20 to 20/200, minimal to no cataracts and no visible macular cysts.
The researchers measured visual acuities with the Early Treatment Diabetic Retinopathy Study (ETDRS) charts. Optical coherence tomography (OCT) was used to calculate retinal thicknesses and to grade third high-reflectance bands.
The study results showed that the ETDRS acuity was best related to the retinal thickness measured at fixation. Visual acuity was maximal in patients with intermediate retinal thickness and lower in patients with more or less retinal thicknesses.
“By linear regression, the decline in acuity for decreasing retinal thickness was steeper in eyes with an absent third high-reflectance band than for eyes with a partially distinct band,” the researchers said. “No decline was noted in eyes with an intact band.”
According to the study, the OCT third high-reflectance band may help predict which patients are more likely to lose visual acuity as retinal thickness declines.
“An increase or decrease in retinal thickness of more than 17 µm at fixation or 11 µm over the central 1 mm at follow-up can be considered a significant (P<.01) change in these patients,” researchers said.
This study was published in the September issue of Investigative Ophthalmology and Visual Science.