A recent study took a closer look at retinal thickness changes in patients with preclinical Alzheimer’s disease, hoping to identify a potential new biomarker. Although several studies have found this population exhibits reduced retinal thickness on OCT, this latest research found Alzheimer’s patients did not demonstrate a significant change in retinal layer thickness compared with controls.

The single-center study included 145 cognitively healthy monozygotic twins of at least 60 years of age. Their preclinical Alzheimer’s disease was defined as cognitive normalcy with the presence of amyloid-beta on positron emission tomography. The researchers calculated binding potential and performed OCT on the subjects at baseline and at 22 months to assess any changes in total and individual inner retinal layer thickness in the macular region and peripapillary retinal nerve fiber layer thickness.

Of the 145 subjects, 11% were positive for amyloid-beta. The researchers compared the rate of change in retinal thickness between those who were positive and negative for amyloid-beta and found no difference. However, they identified a positive association between binding potential and change in inner plexiform layer thickness in the inner macular ring.

Though the researchers found that amyloid-beta positive individuals didn’t demonstrate a difference in rate of change in retinal thickness compared with controls, they did find that subjects with a higher binding potential at baseline showed less inner plexiform layer thinning over time.

The researchers concluded that OCT’s usefulness in preclinical Alzheimer’s disease screening seems limited, but the notable changes in the inner plexiform layer may warrant further research.