Date Published: April 17, 2019
Publisher: Public Library of Science
Author(s): Junko Ouchi, Hiroshi Kunikata, Kazuko Omodaka, Haruka Sato, Hiroyuki Sato, Azusa Ito, Naoko Aizawa, Yoshiki Tanaka, Kazuo Ichikawa, Toru Nakazawa, Sanjoy Bhattacharya.
To investigate the clinical significance of color visual acuity (CVA) in preperimetric glaucoma (PPG) and open-angle glaucoma (OAG).
A total of 123 eyes of 73 subjects (22 normal eyes, 14 PPG eyes, and 87 OAG eyes; mean age: 44.9 ± 10.1 years, age range: 21–64 years) were enrolled. CVA was tested for red, green-yellow, blue-green and blue-purple with a newly developed test.
There was no statistical difference in clinical background factors, including age, sex, intraocular pressure, or spherical equivalent between the three groups. Red VA and blue-green VA were significantly worse in the OAG eyes than in the normal eyes (P = 0.008 and P = 0.015, respectively), although green-yellow VA and blue-purple VA were not significantly worse. Furthermore, red VA and blue-green VA were significantly correlated with MD in a group of eyes with either PPG or OAG (r = -0.23, P = 0.023; r = -0.25, P = 0.012, respectively), but green-yellow VA and blue-purple VA were not.
Red VA and blue-green VA were detectably worse in eyes with OAG, in close association with the degree of functional loss. This suggests that measuring CVA with the new color test described here may be a promising supplement to existing methods of detecting glaucoma and evaluating its severity.
Glaucoma affects over 70 million people worldwide and is the second most common cause of blindness.[1, 2] It is a group of diseases characterized by progressive, irreversible optic neuropathy and degeneration of the retinal ganglion cells and their axons, causing a corresponding loss of the visual field (VF). Thus, simple techniques for the early detection of glaucoma, as well as improved methods for preventing its progression, are important goals of public health research that would have a valuable social impact. Glaucomatous axonal loss and associated structural changes have long been known to precede the manifestation of VF defects, as measured with standard automated perimetry (SAP). New advances in imaging methods, particularly optical coherence tomography (OCT), have allowed the early detection of structural changes, such as the loss of macular thickness and circumpapillary retinal nerve fiber layer thickness (cpRNFLT), enabling new research into preperimetric glaucoma (PPG).[4–11] However, the glaucomatous loss of cpRNFLT is difficult to measure in many eyes, because of various confounding factors, such as disc deformation, tilted disc, and peripapillary atrophy.[12, 13] Thus, other approaches are necessary to complement existing structural analyses and to improve the early detection of glaucoma.
This was a single-center, cross-sectional study. This research followed the tenets of the Declaration of Helsinki and was approved by the Institutional Review Board of the Tohoku University Graduate School of Medicine. Written informed consent was obtained from all subjects.
A total of 123 eyes of 73 subjects (22 normal eyes, 14 PPG eyes, and 87 glaucoma eyes; mean age: 44.9 ± 10.1 years, age range: 21–64 years) were enrolled.
In this study, we tested CVA for R, GY, BG and BP using a paper-based chart with Landolt rings to investigate changes in CVA in PPG and glaucoma patients and healthy controls. Interestingly, we found that R VA and BG VA were detectably impaired in eyes with glaucoma, in close association with the degree of functional loss. Contrarily, CVA for other colors, such as GY VA and BP VA, was not impaired in eyes with glaucoma and was not associated with glaucoma severity. This suggests that measuring CVA with the chart described here may be a promising supplement to existing methods of detecting glaucoma and evaluating its severity.