Inner retinal layer thinning in Parkinson disease

Objective: To quantify retinal thickness in patients with Parkinson disease (PD). Methods: Forty-five eyes of 24 PD patients and 31 eyes of 17 control subjects underwent a comprehensive ophthalmologic examination. We used optical coherence tomography to examine retinal thickness, separately quantifying the inner and outer retinal layers. Intraocular pressure was measured by Goldmann applanation tonometry. Results: The mean (SD) ages of the patients with PD and healthy subjects were 64.0(6.5) years vs 63.5(10.7) years (P=.77). The mean (SD) intraocular pressure was 13.6 (+/-2.7) mm Hg in the PD patients. No difference was found in either the superior or inferior outer retinal layer thickness of PD vs control eyes. The mean (SD) superior inner retinal layer thickness of PD vs control eyes was 88.79 (11.3) μm vs 103.5 (24.3) μm (P=.01), and the mean inferior inner retinal layer thickness was 89.83 (11.1) μm vs 104.0 (23.5) μm (P=.01). Conclusions: The inner retinal layer is significantly thinner in PD patients than in healthy subjects. Idiopathic PD, distinct from glaucoma, needs to be considered in the differential diagnosis of retinal nerve fiber layer thinning.