To report cases of oil droplet cataract, one cause of decreased vision of unknown etiology.

We performed a retrospective chart review analysis of patients referred to the neuro-ophthalmology clinic due to unknown etiology of decreased visual acuity and diagnosed with oil droplet cataract. Clinical features including history, result of ophthalmologic examinations, and clinical course were evaluated.

Among the patients referred to the neuro-ophthalmology clinic due to unknown etiology of decreased visual acuity, 6 patients were diagnosed with oil droplet cataract. The patients ranged from 38 to 63 years of age and their best corrected visual acuities at their first visits were between 0.1 and 0.7. Ophthalmologic examinations including neuro-ophthalmologic tests were normal except for changes in lens nucleus and peculiar fundus reflexes were observed using retinoscopy in all patients. Five eyes of 4 patients underwent cataract surgery and all 5 eyes achieved the best corrected visual acuity of 1.0 or higher.

Oil droplet cataract is a cause of decreased visual acuity of unknown etiology that can be missed. The disease abnormalities are difficult to observe because only subtle changes in lens nucleus are apparent on slit lamp examination; however characteristic fundus reflexes can be identified using retinoscopy. Ophthalmologists should thoroughly understand the oil droplet cataract and diagnose it in the early stages to avoid misdiagnosis and unnecessary costs.