Contrast Discrimination and Global Form Perception in Primary Open-Angle Glaucoma and Primary Angle-Closure Glaucoma

Authors

Siddharth K. Karthikeyan, Manipal College of Health professions
Allison M. McKendrick, University of Melbourne
Vijaya H. Pai, Kasturba Medical College, Manipal
Neetha I.R. Kuzhuppilly, Kasturba Medical College, Manipal

Document Type

Article

Publication Title

Investigative ophthalmology & visual science

Abstract

Purpose: This study explored early (contrast discrimination) and intermediate (global form perception) visual processing in primary subtypes of glaucoma: primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG). We aimed to understand early and intermediate visual processing in POAG and PACG, matched for similar visual field defect severity. Methods: Early visual processing was measured using a contrast discrimination task described by Porkorny and Smith (1997), and intermediate processing using a global form perception task using glass pattern coherence thresholds. Thresholds were determined centrally and at a single midperipheral location (12.5°) in a quadrant without visual field defects. Controls were tested in corresponding quadrants to individuals with glaucoma. Results: Sixty participants (20 POAG, 20 PACG, and 20 age-matched controls), aged 50 to 77 years, were included. Visual field defects were matched between POAG and PACG, with mean deviation values of -6.53 ± 4.46 (range: -1.5 to -16.85) dB and -6.2 ± 4.24 (range: -1.37 to -16.42) dB, respectively. Two-Way ANOVA revealed significant differences in thresholds between the glaucoma groups and the control group for both contrast discrimination and global form perception tasks, with higher thresholds in the glaucoma groups. Post hoc analyses showed no significant contrast discrimination difference between POAG and PACG, but POAG had significantly higher thresholds than PACG for form perception. Conclusions: In form perception, POAG showed slightly worse performance than PACG, suggesting that individuals with POAG may experience more severe functional damage than PACG of similar visual field severity.

First Page

33

DOI

10.1167/iovs.65.5.33

Publication Date

5-1-2024

Recommended Citation

Karthikeyan, Siddharth K.; McKendrick, Allison M.; Pai, Vijaya H.; and Kuzhuppilly, Neetha I.R., "Contrast Discrimination and Global Form Perception in Primary Open-Angle Glaucoma and Primary Angle-Closure Glaucoma" (2024). Open Access archive. 6569.
https://impressions.manipal.edu/open-access-archive/6569