Hemispheric analysis for detecting intraretinal thickness alterations in mild cognitive impairment and Alzheimer’s disease

Abstract

Purpose : Detail analysis of tomographic thicknesses of intraretinal layers may provide more sensitive detection of neurodegeneration in mild cognitive impairment (MCI) and Alzheimer’s disease (AD). Our study was to evaluate hemispheric intraretinal thickness maps in MCI and AD and their diagnostic values compared to conventional ganglion cell layer thickness analysis.

Methods : Totally 29 patients diagnosed with AD (n=12) and MCI (n=17) and 22 age matched controls were recruited. All subjects were imaged with custom ultrahigh-resolution OCT (URH-OCT) to obtain 6 intraretinal thickness maps and Zeiss Cirrus HD-OCT for obtaining ganglion cell-inner plexiform layer (GCIPL) thickness map. Orion software was used and further analysis was done using hemispheric partition and the Early Treatment Diabetic Retinopathy Study (ETDRS) methods. Receiver operating characteristic curves were calculated and sensitivity and specificity were used to evaluate diagnostic performance.

Results : Using hemispheric partition, the retinal nerve fiber layer (RNFL) thickness of nasal inferior, inner temporal superior (ITS), inner temporal inferior (ITI), inner nasal inferior (INI) and outer nasal inferior sectors and the inner nuclear layer (INL) thickness of nasal superior, ITS, ITI and INI sectors were significantly thinner in the AD than control (p<0.05). The GCIPL thickness of superior, ITS, ITI, INI and outer nasal superior (ONS) sectors in the AD were significantly thinner than control (p<0.05). In contrast, only GCIPL thickness of superior, ITS, ITI, INI, ONS and inner nasal superior area in the MCI were significantly thinner than control (All p<0.05). Using EDTRS partition, GCIPL thickness of the inner superior sector in MCI was significant thinner than control (p<0.05). Interestingly, GCIPL analysis by the conventional method only found a significant thinning located at inferior temporal sector (p<0.05). The best distinguishing parameter was the ITS thickness of INL (0.76; 95% confidence interval [CI]=0.59–0.92) for AD patients and the ONS thickness of GCIPL by UHR-OCT for MCI (0.81; 95% CI=0.63–0.99).

Conclusions : The thinning of the RNFL, GCIPL and INL can be detected by the hemispheric method using UHR-OCT in the AD and MCI patients, which appeared to be more sensitive for early detection of retinal neurodegeneration than the EDTRS partition and conventional GCIPL analysis.

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