Spectral Domain Optical Coherence Tomography Identifies Outer Retina Thinning in Frontotemporal Lobar Degeneration

Abstract

Purpose : Alzheimer’s disease (AD) is associated with thinning of inner retina layers (retinal nerve fiber layer and ganglion cell layer) on spectral domain optical coherence tomography (SD-OCT). Frontotemporal lobar degeneration (FTD) is an age-related dementia with distinct pathology, and up to 30% of clinically diagnosed FTD cases have a neuropathological diagnosis of AD. We determined if the retina has biomarker potential for FTD.

Methods : We consecutively enrolled 38 cases with clinical FTD (mean age 66 years) and 44 controls (mean age 56 years). Cases were diagnosed by a neurologist. Subgroups of presumed molecular pathology (tauopathy, TAR DNA Binding Protein–43, AD, and unknown pathology) were determined by clinical diagnosis, a cerebrospinal fluid biomarker (total tau:amyloid β 1-42), and genetic markers to identify presumed FTD subtypes and AD. Retinal structure was examined with a standard SD-OCT (Spectralis, Heidelberg Engineering, Carlsbad, CA) protocol and retinal layers segmented by a masked analyst with the Iowa Reference Algorithm (v3.6) for a standard ETDRS (Early Treatment Diabetic Retinopathy Study) grid. Eyes with poor image quality, glaucoma or optic nerve disease, high refractive error, or macular disease were excluded. SD-OCT parameters were compared between eyes of cases (n=50 eyes) and controls (n=69 eyes) using a generalized linear model that accounted for inter-eye correlation.

Results : Controlling for age, sex, and race, the cases had a thinner outer retina than controls (p < 0.05, Table 1). There was thinning of the outer nuclear layer (ONL) and ellipsoid zone (EZ) in cases (p < 0.05, Table 1), and the ONL was the main driver of outer retina thinning. Cases and controls had similar thicknesses for inner retinal layers (Table 1). Subgroup analysis demonstrated that the presumed FTD tauopathy subgroup (n=31 eyes) had thinner ONL and EZ than controls (p < 0.05), and all other subgroups but the presumed AD subgroup showed a trend of ONL thinning (Table 2).

Conclusions : In contrast to AD, FTD is associated with predominant thinning of the outer retina rather than the inner retina.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

*From the generalized estimating equations that account for inter-eye correlation. Adjusted for age, sex, and race.

 

*Compared to controls and adjusted for age, sex, and race. From the generalized estimating equation that accounts for inter-eye correlation.