Global Retinal Sensitivity Significant in Early, Intermediate AMD

Age-related macular degeneration (AMD) had a statistically significant relationship with global retinal sensitivity changes under mesopic and scotopic lighting, according to a review published in Eye. This relationship was found specifically in early and intermediate AMD.

AMD can lead to adverse effects on a patient’s quality of life due to vision and functional changes. Visual fields for functional testing for AMD have been proposed as a way to assess the visual function of those with AMD, but their role in practice has not been specifically defined. This review aimed to evaluate the significance of visual field defects found under mesopic and scotopic lighting in terms of clinical relevancy in patients with early and intermediate AMD. The review also aimed to determine the best test for early and intermediate AMD.

Woman having vision problems | Image credit: StockPhotoPro - stock.adobe.com

All studies that could be included were those that included visual field tests done under mesopic or scotopic lighting. Participants needed to be treatment naïve and have eyes with early and/or intermediate AMD. Devices that measured different light sensitivities were categorized as visual field testing. PubMed and Embase were searched for the studies from the beginning of their index through to May 14, 2022.

The researchers were looking for global mean sensitivity (MS) as their primary outcome, which was measured using the average sensitivity in decibels (dB) in the retina area. This was done in a comparison between early/intermediate AMD and normal eyes. All studies were evaluated for a risk of bias.

There were 77 studies included in the review, all of which were observational. The number of eyes evaluated ranged from 3 to 319, with 101 visual field protocols used across the 77 studies. A high risk of bias was found in at least 1 domain of 74 studies, with patient selection having a high risk of bias in 64 studies and comparability of study groups having a high risk of bias in 35 studies.

A total of 42 studies were used to calculate the global MS for patients with early/intermediate AMD compared with normal eyes. There were 2587 eyes with early/intermediate AMD and 1348 with normal eyes. Global MS was found to be lower in patients with early/intermediate AMD compared with the normal group with an effect size of –0.9 (95% CI, –1.04 to –0.75). In a further meta-analysis to determine any confounding factors, the only factor that affected outcomes was the device used. Radius, background luminance, and adaptation time were not found to significantly affect outcomes.

Global MS was reduced when comparing intermediate AMD vs early AMD with a medium effect size of –0.58 (95% CI, –0.88 to –0.29) which was equivalent to a dB of –2.55 (95% CI, –3.62 to –1.47). Global MS was also reduced in the presence of RPD. Global MS was also reduced in longitudinal follow-up compared with baseline at –0.62 (95% CI, –0.84 to –0.41).

Comparing lighting found that mesopic MP-1 had the greatest effect sizes of –1.72 (95% CI, –2.34 to –1.1); MAIA devices also had similarly high effect sizes (–0.99; 95% CI, –1.26 to –0.72).

There were some limitations to this study. For instance, there are less demanding ways of measuring low-light function, including low-luminance visual acuity, that have not been reviewed. Downstream effects of these visual field tests were not evaluated.

The researchers concluded that global retinal sensitivity changes under mesopic and scotopic lighting had statistical significance in patients with early/intermediate AMD, specifically when using MP-1 and MAIA devices in mesopic light. Real-world patient outcomes using these results should be the subject of future research.

Reference

Trinh M, Kalloniatis M, Khuu SK, Nivison-Smith L. Retinal sensitivity changes in early/intermediate AMD: a systematic review and meta-analysis of visual field testing under mesopic and scotopic lighting. Eye. Published online March 18, 2024. doi:10.1038/s41433-024-03033-0