Quantitative analysis of related parameters of retinal nerve fiber layer and ganglion cell complex thickness in patients with different degrees of Parkinson's disease.

objectiveA quantitative analysis was performed to evaluate the morphologic changes of the retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC) in patients with Parkinson's disease (PD).

methodsThirty PD patients were enrolled, and they were allocated to the mild-to-moderate PD group (n = 15) or severe PD group (n = 15) according to the severity of PD. Twenty healthy volunteers (20 eyes) were included as controls. Optical coherence tomography (OCT) was used to measure the thickness of mean RNFL and each of the sectors: temporal-upper (TU), superior-temporal (ST), superior-nasal (SN), nasal-upper (NU), nasal-lower (NL), inferior-nasal (IN), inferior-temporal (IT), temporal-lower (TL). The thickness of macular GCC, superior GCC, and inferior GCC was also measured.

resultsNo difference was found between the three groups with respect to age, sex and disease course (p > 0.05). The mean RNFL thickness was 118.15 ± 10.25 µm in the control group, 96.12 ± 9.45 µm in the mild-to-moderate PD group, and 80.48 ± 10.35 µm in the severe PD group. Significant differences were found in the mean RNFL thickness and thickness of TU, IN, IT and TL sectors among the three groups (p < 0.05). These values, mean RNFL, TU, IN, IT, and TL, were lower in both the PD groups than those in the control, among them the severe PD group had the lowest values. A quantitative analysis of the macula GCC was also performed. Overall, there were significant differences in mean macula, superior, and inferior GCC thickness among the three groups (p < 0.05). The two PD groups had lower values of mean macula, superior, and inferior GCC thickness than that in the controls (p < 0.05); and the severe PD group had lowest values of these parameters.

conclusionIn this study, significant thinning of RNFL and macular GCC was found in PD patients. The more serious the illness, the more the thickness becomes thinner. The OCT measurement was found useful in detecting the structural alterations in the retina of PD. The technique may be useful in follow-up of the disease progression after further validation.