As the second leading cause of blindness, the development of simple methods to detect glaucoma as early as possible is a critical research goal. The most important components of human vision are:

• Spatial perception, made up of visual acuity (VA) and contrast sensitivity 
• Temporal perception, or the time it takes to process visual stimuli
• Color perception

Most glaucoma patients do not exhibit reduced VA until the later stages of the disease. This makes it difficult to detect early-stage glaucoma with standard VA testing. Researchers of a 2019 study, published in the journal PLOS, created a new test to assess the significance of color visual acuity (CVA) as an early indicator of glaucoma.*

What they did

The research team hypothesized that CVA might change for different colors in eyes with glaucoma and that those changes might be related to glaucoma severity. To test their hypothesis, the team recruited 73 participants, aged 21-64 (mean age 44.9), from Tohoku University Hospital. 

A total of 123 eyes were involved in the study:

• 22 normal eyes 
• 14 eyes with preperimetric glaucoma (PPG)
• 87 eyes with open-angle glaucoma (OAG) 

The participants first underwent an ophthalmological exam and then the newly developed test, which includes a paper chart with colored Landolt rings (i.e., incomplete circles). 

CVA was tested for:

• Black-white (BW)
• Red (R)
• Green-yellow (GY)
• Blue-green (BG)
• Blue-purple (BP)

What they found

Results of the study revealed that:

• Red (R) and blue-green (BG) VA were significantly worse in eyes with OAG than in the normal eyes and closely associated with glaucoma severity and functional loss.
• Green-yellow (GY) and blue-purple (BP) VA were not significantly worse in eyes with glaucoma than in normal eyes and not closely associated with glaucoma severity and functional loss
• Black-white (BW) VA was not significantly lower.

What it means

This study is the first to show that CVA for some colors was noticeably lower in eyes with glaucoma than in healthy eyes. These results:

• Point to glaucoma as a cause of acquired color vision defects
• Recommend the new chart-based color test as a promising addition to current methods of diagnosing glaucoma and assessing its severity

*Ouchi, J., Kunikata, H., Omodaka, K., Sato, H., et al. (2019, Apr. 17). Color Visual Acuity in Preperimetric Glaucoma and Open-Angle Glaucoma. PLOS One. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0215290