Long-term follow-up of choroidal changes following COVID-19 infection: analysis of choroidal thickness and choroidal vascularity index

Objective: To investigate subclinical choroidal involvement in patients with systemic coronavirus disease 2019 (COVID-19) infection and evaluate its long-term course.Materials and Methods: This prospective, longitudinal study included 32 eyes of 16 COVID-19 patients and 34 eyes of 17 age-matched healthy control subjects. All the participants had a detailed ophthalmologic assessment, including visual acuity assessment, slit-lamp exami-nation, and indirect ophthalmoscopy. Enhanced depth optical coherence tomography imaging of the posterior pole and peripapillary region was performed in the early (days 15-40) and late (ninth month) postinfectious periods. Choroidal vascularity index (CVI) was calculated using ImageJ software (National Institutes of Health, Bethesda, Md.).Results: None of the patients had any examination finding associated with the ocular involvement of COVID-19. Subfoveal choroidal thickness (SFCT) decreased significantly in the early postinfectious period compared with the healthy control individuals (p = 0.045). SFCT increased significantly in the late postinfectious period compared with the early period (p = 0.002), and the difference between patients and control individuals became statistically insignificant (p = 0.362). There was a similar trend for the peripapillary choroidal thickness measure-ments. CVI remained unchanged (p = 0.721) despite the significant decrease in SFCT and total choroidal area (p = 0.042), indicating that this decrease occurred both in choroidal stroma and in blood vessels. CVI remained unchanged in the late postinfectious period (p = 0.575) com-pared with the early period, indicating that recovery occurred in the entire choroidal tissue.Conclusion: This study demonstrates that choroidal thickness was reduced in all measured areas and that this decrease affected all cho-roidal layers. This choroidopathy was reversible and recovered in the ninth postinfectious month.