Epidemic keratoconjunctivitis (EKC) due to adenovirus type 8 affected 126 (7%) of 1870 ophthalmology clinic patients during an outbreak. Risk factors and mode of transmission were studied by comparing cases (n = 58) and controls (n = 200) for exposure to risk factors. Pneumotonometry (odds ratio [OR], 10.5; 95% confidence interval [CI], 4.0-27.7), multiple clinic visits (OR, 5.9; 95% CI, 3.3-10.6), and contact with an infected physician (OR, 3.3; 95% CI, 1.2-9.0) were significant risk factors for infection. The hands of 3 patients and 3 physicians with EKC were cultured before and after hand washing to assess adenovirus removal; 3 had hand cultures positive for adenovirus after hand washing. In conclusion, this outbreak appeared to be due to inadequate disinfection of instruments, especially pneumotonometers, and finger-to-eye transmission by health care workers. Hand washing did not reliably remove adenovirus from contaminated fingers. Gloving for exam of eyes with EKC may help prevent transmission. Ophthalmologists with EKC were a significant risk factor for patients and should be furloughed for the duration of communicability.