A complete ophthalmic examination was performed, including refraction, visual acuity, visual field, biomicroscopic slit lamp examination, electroretinography (ERG), and funduscopy. Best-corrected visual acuity was measured in each eye with a Landolt chart, and the decimal values were converted to the logarithm of the minimal angle of resolution (logMAR) units. The visual field was assessed by Goldman kinetic perimetry (V-4e, I-4e, and I-2e targets). The clinical diagnosis was based on visual acuity, visual field, fundus photographs, and ERG findings. ERG recordings were performed in accordance with the guidelines provided by the International Society for Clinical Electrophysiology of Vision, using a monopolar contact lens electrode. Basic retinal imaging was performed using color fundus photographs, and an optical coherence tomography (OCT) device (Spectralis; Heidelberg Engineering, Heidelberg, Germany) was also used in some patients.