Introduction:Neuronal intranuclear inclusion disease (NIID) is a neurodegenerative disorder that produces a broad spectrum of clinical conditions such as dementia, upper motor neuron involvement, extrapyramidal symptoms, and neuropathy. Some studies have reported ophthalmological conditions associated with the disease; however, the details of these conditions remain unclear.Patient concerns:We report a 63-year-old Japanese female with cognitive decline, blurred vision, photophobia, and color blindness at 52 years of age who was diagnosed with cone dystrophy. She also had anxiety, insomnia, depression, delusions, hallucinations, a wide-based gait with short steps, and urinary incontinence.Diagnoses, interventions, and outcomes:Magnetic resonance imaging revealed diffuse cerebral white matter changes and subcortical hyperintensity on diffusion-weighted imaging. Skin biopsy showed p62-positive intranuclear inclusions in sweat glands.NOTCH2NLCgene analysis revealed abnormal GGC expansion; therefore, NIID was diagnosed.Conclusion:NOTCH2NLCmutation-positive NIID may be associated with retinal dystrophy. Brain magnetic resonance imaging and skin biopsy are helpful diagnostic clues, and gene analysis is crucial for accurate diagnosis and appropriate management.