Thicker macula tied to better vision

In healthy eyes, a thicker macula and ganglion cell-inner plexiform layer (GCIPL) is associated with better visual functioning, according to a recent Singapore study.

“In our large, multi-ethnic population-based study, we found that a thicker optical coherence tomography (OCT)-measured average macular thickness and GCIPL thickness were both independently associated with better best-corrected visual acuity (BCVA) and visual functioning scores,” researchers said.

The study included 4,450 participants (mean age, 58.6±8.6 years; 51.4 percent female), contributing 7,744 eyes for analysis. The mean BCVA was 0.10±0.11, while the mean central subfield and macular thicknesses were 246.1±21.5 µm and 276.0±13.4 µm, respectively. GCIPL had an average thickness of 80.4±7.1 µm. [Sci Rep 2020;10:6142]

Most OCT parameters were significantly associated with BCVA even after multivariable adjustment. Each 20-µm increment in mean GCIPL thickness, for example, correlated with a significant improvement in BCVA (β, –0.031, 95 percent confidence interval [CI], –0.047 to –0.014; p<0.001).

The same was true for each 20-µm increase in both average macular (β, –0.009; 95 percent CI, –0.014 to –0.003; p=0.001) and central subfield (β, –0.009; 95 percent CI, –0.014 to –0.004; p<0.001) thickness. Outer retinal thickness was unrelated to BCVA (β, 0.000, 95 percent CI, –0.010 to 0.010; p=0.983).

This was reflected in patient sentiment, as measured by the 11-item, interviewer-administrated visual functioning questionnaire (VF-11). Fully adjusted analysis showed that a 20-µm increase in average GCIPL (β, 0.05, 95 percent CI, 0.01–0.08) and macular (β, 0.04, 95 percent CI, 0.01–0.06) thickness led to a 0.9-percent and 0.7-percent increase in VF-11 scores, respectively.

The same magnitude increases in central subfield and average outer retinal thickness likewise yielded slight improvements in VF-11 scores but failed to reach significance.

“[O]ur study demonstrates that in an adult Asian population with healthy eyes, thicker macula and GCIPL were associated with better VA and better visual functioning,” the researchers said. “To the best of our knowledge, this is a novel finding in healthy eyes.”

The present study enrolled patients from the Singapore Epidemiology of Eye Diseases study, excluding those who had undergone previous retinal procedures and had pre-existing retinal diseases. Subjective refraction was performed to measure BCVA, while spectral-domain OCT was used to obtain images of the macula.

“These findings support our initial hypothesis that in healthy eyes, a thicker macula is associated with better vision and vision-specific functions. This finding may help to partially explain the subtle variation in vision and visual function among nonpathological eyes that is sometimes observed in clinic,” the researchers said.

“Overall, despite the statistically significant associations observed between macular parameters and visual functions, it should also be noted that the observed effect estimates were generally small. Hence, the clinical impact of these observed associations remained to be evaluated in future studies,” they added.