Dr. John Miller’s presentation, “Quantitative Contrast Sensitivity Longitudinal Changes Correlate Better Than Visual Acuity With Geographic Atrophy Progression,” at the American Society of Retina Specialists 2024 Annual Meeting addressed the need to investigate functional endpoints beyond visual acuity (VA) for monitoring geographic atrophy (GA) that may better correlate with geographic atrophy (GA) size.
Although fundus autofluorescence (FAF) is the gold standard for GA diagnosis, functional outcomes of GA are not as clear. Clinical trials have shown that VA and some other functional tests correlate weakly with GA size and progression. Recently, the focus has moved toward OCT biomarkers that are more sensitive to early alterations in GA, according to Dr. Miller. Even though contrast sensitivity (CS) changes can appear early in age-related macular degeneration (AMD), they are not routinely tested for in clinical practice.
The Quantitative Contrast Sensitivity Function Test
Dr. Miller then discussed the findings of a prospective observational study conducted at Mass Eye and Ear to investigate correlations between total GA size and the quantitative contrast sensitivity function (qCSF) test using spectral-domain (SD)-OCT for GA diagnosis and FAF for GA size. Eyes with GA and fovea involvement were tested: 83 cross-sectionally and 30 longitudinally. Minimum follow-up time was between 6 months and 1 year.
SD-OCT and FAF were performed on the same day as qCSF testing. Total GA size was measured by 2 masked graders on FAF using the semiautomatic Heidelberg RegionFinder tool. Primary endpoints included total GA size, VA, and qCSF outcomes.
Total GA Correlated With Contrast Sensitivity
Regression models controlling for age, lens status, and GA pattern showed that total GA was associated with multiple qCSF outcomes including area under the log contrast sensitivity function and contrast sensitivity thresholds but was not associated with VA. Similarly, Pearson correlations revealed that total GA size was correlated with qCSF outcomes but not with VA. Longitudinal change in total GA size on FAF was significantly associated with change in qCSF, but not with general VA or change in VA. Results of the qCSF test also correlated with visual field quality of life (VFQ) scores but not VA in AMD. Strong test–retest reliability was seen in 121 eyes.
Contrast Sensitivity Tracks Progression and Measures Treatment Effect
When asked about differentiating later-stage AMD from earlier stages, Dr. Miller said, “We have the largest dataset of contrast sensitivity in dry AMD, and we have shown that you can differentiate state and it is better than VA.” Even in the intermediate disease group, the qCSF test showed disease progression over time. Dr. Miller noted that type of retinopathy disease also can be differentiated by the qCSF test.
Advantages of using the qCSF test include the following:
- Tests a wide range of contrast and spatial frequencies
- Allows for personalization and gaining of more information through use of an active learning-based algorithm
- More time-efficient—reduces the number of trials from hundreds to dozens
- Can generate a contrast curve in 2–5 minutes per eye
In concluding his talk, Dr. Miller said that about 50% of his clinical practice gets tested with this device every day and that “contrast sensitivity seems to be a better functional endpoint to track GA progression and to measure treatment effect in AMD routine practice and clinical trials.”