Large Hypertransmission Defects Show Limited Correlation to Visual Function in Early AMD

In intermediate AMD, large hypertransmission defects (≥250µm) may indicate disease progression and serve as a structural biomarker for evaluating visual function deterioration. Photo: Nanegrungsunk O, et al. Eye (Lond). September 15, 2024. Click image to enlarge. For patients with age-related macular degeneration (AMD), regions of hypertransmission (HT) on OCT represent retinal pigment epithelium loss or damage, elevating the risk of progression for intermediate AMD (iAMD) eyes. Large HT defects (≥250µm) are predictive of geographic atrophy onset, the growth and occurrence of which are suggested as potential outcome measures for iAMD trials. Researchers recently conducted a study to analyze the presence and implications of HT in normal aging and in patients with early and intermediate AMD, as well as analyze how large HT defects contribute to impaired visual function among these populations. The results, published in American Journal of Ophthalmology, suggest that while large HT defects may not be a prominent indicator of early AMD progression, it could serve as a useful biomarker for later stages of the disease.Conducted under the Alabama Study on Early Age-Related Macular Degeneration 2 (ALSTAR2), this prospective cohort study included participants aged 60 and older diagnosed with normal macular health (n=236), early AMD (n=134) or iAMD (n=90). A total of 460 eyes from 460 patients were analyzed at baseline, and 339 eyes were followed up after three years. Participants underwent comprehensive testing, including spectral domain OCT angiography (OCT-A), color fundus photography and various vision tests.Key findings indicated that HT of any size was most common in iAMD eyes (86.7%), compared to early AMD (35.1%) and normal eyes (3.8%). Interestingly, large HT defects were statistically significantly more prevalent in normal (13.3%) and iAMD (4.2%) eyes than in early AMD (0.4%).At both baseline and follow-up, eyes presenting with large HT defects exhibited reduced photopic contrast sensitivity, mesopic contrast sensitivity and prolonged rod intercept time, indicating impaired rod-mediated dark adaptation. For instance, rod intercept time was significantly prolonged in eyes with large HT defects (32.0 minutes) compared to those without the feature (18.5 minutes). Low luminance visual acuity and scotopic light sensitivity were also worse among participants with large HT defects at three years.These findings, the researchers explain in their paper, indicate a limited correlation between the presence of HT and visual function, suggesting that the biomarker may be more indicative of overall disease severity rather than a direct result of localized pathology underlying its development. Considering this, the authors hypothesize that while large HT defects “may not be a major structural correlate” in early stages of AMD, their presence could be valuable in monitoring patients who are at heightened risk for progressing to later stages of the disease. They added, “rod-mediated dark adaptation delay, which starts in aging, is well underway before the appearance of noteworthy numbers of large HT defects.”In conclusion, the study authors wrote, “Our data may help narrow the progression window where large HT defects can serve as important biomarkers for disease progression.”Click here for the journal source. Johnston W, Kim SS, Kar D, et al. Hypertransmission and vision in aging and age-related macular degeneration: longitudinal data from ALSTAR2. Am J Ophthalmol. August 21, 2025. [Epub ahead of print]. This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.