BACKGROUND: To minimize the risk of viral transmission, ophthalmology practices limited face to face encounters to only patients with urgent and emergent ophthalmic conditions, in the weeks after the start of the COVID-19 epidemic in the United States. The impact of this is unknown. METHODS: We did a retrospective analysis of the change in the frequency of ICD-10 code use and patient volumes in the six weeks before and after the changes in clinical practice associated with COVID-19.RESULTS: The total number of encounters decreased four-fold after the implementation of clinic changes associated with COVID-19. The low vision, pediatric ophthalmology, general ophthalmology, and cornea divisions had the largest decrease of in-person visits. Conversely, telemedicine visits increased sixty-fold. The number of diagnostic codes associated with ocular malignancies, most ocular inflammatory disorders, and retinal conditions requiring intravitreal injections increased. ICD-10 codes associated with ocular screening exams for systemic disorders decreased during the weeks post COVID-19. CONCLUSION: Ophthalmology practices need to be prepared to experience changes in practice patterns, implementation of telemedicine, and decreased patient volumes during a pandemic. Knowing the changes specific to each subspecialty clinic is vital to redistribute available resources correctly.