For glaucoma suspects, retinal nerve fiber layer (RNFL) thickness may be a more precise predictor of the disease than Bruch’s membrane opening minimum rim width when measured by spectral-domain OCT (SD-OCT), a team of researchers from Duke University suggest.

Their observational cohort study, which was published in Ophthalmology Glaucoma, enrolled 113 eyes of 81 patients who were suspected of having glaucoma based on their optic nerve appearance.

The investigators measured the patients’ RNFL thickness and Bruch’s membrane opening minimum rim width with SD-OCT. All participants had normal visual fields at the time of imaging but were considered suspects based on the appearance of the optic disc during clinical examination. Eyes were classified as glaucomatous or non-glaucomatous based on previous imaging that showed progressive glaucomatous change in the appearance of the optic nerve or RNFL. For each parameter, researchers calculated the area under the receiver operating characteristic (AROC) curve and the sensitivity with fixed specificities of 80% and 95%.

Of the 113 eyes suspected of having glaucoma, 46% had progressive glaucomatous optic nerve changes and were classified as having pre-perimetric glaucoma. Sixty-one eyes (patients who were followed untreated for an average of approximately nine years, 54%) had no progressive glaucomatous optic nerve changes and were classified as normal. The study noted the global RNFL thickness measures were more accurate than the global Bruch’s membrane opening minimum rim width measures. The sensitivity (at 95% specificity) was 60% for the RNFL thickness parameters and 40% for the Bruch’s membrane opening minimum rim width parameter.

The global RNFL thickness parameters that were the most accurate included superotemporal, inferotemporal and superonasal. The only Bruch’s membrane opening minimum rim width parameter with a similar accuracy was inferotemporal.