Research data verify age-related choroidal atrophy but not choroidal thinning

April 15, 2010

Choroidal thinning is not a feature of glaucoma nor does choroidal thickness correlate with retinal nerve fiber layer thickness, according to new study findings.

Naples, FL-Choroidal thinning is not a feature of glaucoma nor does choroidal thickness correlate with retinal nerve fiber layer (RNFL) thickness, according to authors of a recent study, in which spectral-domain optical coherence tomography (SD-OCT) (Spectralis HRA+OCT, Heidelberg Engineering Inc.) was used to measure choroidal thickness. These results did, however, replicate previous findings of age-related choroidal atrophy (ARCA).

The study included SD-OCT data from 21 glaucomatous eyes and 19 normal eyes derived from a population seen in the glaucoma clinic for suspected glaucoma.

Ehrlich is pursuing dual degrees in medicine at Weill Cornell Medical College and in public health at the Joseph L. Mailman School of Public Health, Columbia University, New York. The senior investigator in the research was Nathan M. Radcliffe, MD, assistant professor of ophthalmology, Weill Cornell Medical College.

"Multiple research teams are working on how best to define the choroid and to determine which scanning and analysis protocols are best," Ehrlich said.

"Published literature includes reports by Richard Spaide, MD, of choroidal atrophy with increasing age and by Yin et al. of choroidal insufficiency as a finding in primary open-angle glaucoma," Ehrlich explained. "While we confirmed the age-dependency of choroidal thickness, based on our results, measurement and evaluation of the choroid does not appear to be a useful adjunct to current methods for glaucoma surveillance and management."

Investigators were able to use these data that had already been collected during routine care since they were of high-enough quality to replicate previous work and since the peripapillary retina seemed to be the most important area to examine in glaucoma.

The reported study included data from 19 eyes of patients who presented to the clinic for glaucoma evaluation but had no clinical, structural, or functional evidence of disease and from 21 eyes with diagnosed glaucoma based on two reliable and repeatable visual fields (Humphrey Matrix 24-2, Carl Zeiss Meditec). There was no statistically significant difference in mean age between the two study groups.

For each patient's scan, the manufacturer's software was used to segment and measure the RNFL and was adapted to segment the choroid manually by delineating the area between the outer retinal pigment epithelial border and the inner scleral wall. The software calculated the thickness of that region, representing choroidal thickness.

Global thickness measurements and measurements at the quadrants of the peripapillary region were determined for the choroid by two observers masked to the patient's diagnosis, and one observer measured peripapillary atrophy (PPA) from optic nerve photographs.

Both observers performed choroidal thickness measurements at 238 peripapillary locations from 35 eyes, and comparison of the results showed excellent correlation between their measurements, demonstrating the repeatability of the method used for assessing choroidal thickness.