Purpose
To perform segmental analysis of the retinal single-layers in de novo drug-naïve Parkinson’s disease (PD) in order to assess the presence and degree of structural retinal change in the early stage of PD.
Methods
Fifty-four de novo PD (99 eyes) and 23 age-matched controls (39 eyes) were recruited. General ophthalmologic examination and optical coherence tomography (OCT) scans were done. Using automated segmentation software, the parafoveal retina was separated into 10 layers and the mean thickness of each retinal layer was calculated in the 9 sectors of the Early Treatment of Diabetic Retinopathy Study (ETDRS) macular map. The whole retinal layer (WRT), retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL) and photoreceptor layer (PR) thicknesses were compared between de novo PD and control.
Results
There were no significant differences in baseline demographic factors such as age, sex, logMAR visual acuity, spherical equivalent and axial length. De novo PD patients showed OPL thinning in the inferior and nasal sectors of the inner ETDRS circle (35.67±8.75 vs 39.79±12.00 mm, p=0.056 and 33.69±8.06 vs 39.79±11.04 mm, p=0.003). Conversely, the GCL inferior and nasal sectors of the outer circle, the center fovea of the GCL and IPL, and ONL nasal sector of the inner circle showed increased thickness compared to control. (33.43±4.06 vs 30.87±3.65 mm, p=0.001, 38.73±4.01 vs 37.03±4.11 mm, p=0.027, 13.58±5.58 vs 11.82±2.53 mm, p=0.012, 19.37±3.73 vs 18.03±1.94 mm, p=0.006, and 70.47±12.21 vs 65.15±14.43 mm, p=0.030).
Conclusions
Segmental analysis of the retinal single-layers showed evident structural changes in de novo drug-naïve PD. Future studies are warranted to further characterize the topographic pattern and the degree of retinal single-layer change in early stage PD.