Structural, functional asymmetry associated in glaucoma patients

DENVER – Researchers found significant associations between decreasing visual field sensitivity and increasing structural asymmetry, according to a presentation at the American Academy of Optometry meeting.

Ellen M. Beebe, OD, discussed the study with Primary Care Optometry News following the meeting.

"The purpose of the study was to identify if significant structure-function relationships could be identified in a group of subjects suspicious for glaucoma," she told PCON. "We surmised that the study would help us determine which structural parameters are worthy of further study and may ultimately aid in earlier and more sensitive diagnosis of glaucoma.”

Beebe and colleagues used 110 participants that were participating in a longitudinal, observational glaucoma study. The participants were identified as ocular hypertension patients or glaucoma suspects. Of the 110 participants, 105 were included in the 24-2 visual field analysis, and 75 were included in the 10-2 visual field analysis, Beebe told PCON.

They utilized the Spectralis HD-OCT (Heidelberg Engineering) to measure the retinal nerve fiber layer (RNFL) as well as macular thickness in the participants. Additionally, researchers calculated several values for analysis, including intra-eye macular thickness disparity, lowest eye global RNFL, inter-eye macular thickness asymmetry and inter-eye RNFL asymmetry, Beebe described.

Results showed that structural asymmetry was correlated with 24-2 visual field parameters. Researchers reported in the abstract that the strongest relationship was between inter-eye RNFL asymmetry and 24-2 mean deviation asymmetry.

"Although none of the subjects had any identifiable visual field loss, there were disparities in mean deviation (MD) and pattern standard deviation (PSD) that we used to compare to our structural imaging," Beebe explained to PCON. "We found robust correlations between increasing structural asymmetry and increasing functional asymmetry on the 24-2 visual field test. The most significant parameters included inter-eye macular thickness asymmetry and global RNFL asymmetry.

"The results are remarkable given that all subjects in this study had ‘normal’ visual fields and the small ranges of the visual field parameters (MD, PSD) in the study," she concluded. "Our findings support the premise that structural asymmetry is present and detectable in early ‘pre-perimetric’ glaucoma." – by Chelsea Frajerman

Disclosures: The authors have no relevant financial disclosures.