This article was originally published in a sponsored newsletter.

A healthy corneal endothelium is essential for scleral lens wear. Scleral lenses may be contraindicated in some instances (e.g., conditions affecting the corneal endothelium such as reduced endothelial cell density and Fuchs’ endothelial corneal dystrophy).¹ Various techniques may be utilized for successful scleral lens wear including peripheral lens fenestrations and channels within the lens.

COVID-19, caused by the highly contagious SARS-CoV-2 RNA virus, primarily manifests as a respiratory illness.² However, many ocular symptoms including epiphora, conjunctival congestion, photophobia, and eye pain have also been reported.²

Several studies using specular microscopy on patients who had COVID-19 show differing clinical characteristics and recovery times. Erdem and colleagues found significant reductions in endothelial cell density (ECD) and hexagonality (HEX), along with increases in coefficient of variation (CV) and central corneal thickness (CCT) in patients who had COVID-19 compared to controls.³ Similarly, Oren and Kocabas reported decreased ECD and HEX, with an enlarged CV in the cell area.⁴ Both studies accentuated minute alterations in the corneal endothelium during the COVID-19 recovery phase.

One study evaluated the long-term impact of COVID-19 on the morphology of corneal endothelial cells in patients displaying ocular symptoms, aiming to assess the involvement of the cornea in those who have recovered.² By utilizing a retrospective chart review, 54 patients who had symptoms of ocular irritation due to COVID-19 were recruited four to six months after their initial diagnosis at Istanbul University Cerrahpasa Medical Faculty. A control group consisted of 72 patients matched for age and sex without ocular pathology.

Noncontact specular microscopy was conducted 156 ± 16 days post-COVID-19 diagnosis using the center method. The parameters analyzed included HEX, ECD, CV, and CCT. In the COVID-19 patient group, ocular symptoms encompassed epiphora, conjunctival hyperemia, foreign body sensation, chemosis, and ocular secretion.

In the COVID-19 group, the mean ECD was 2770 ± 31 cells/mm² and in the control group, the mean ECD was 2897 ± 26 cells/mm². In COVID-19 patients who had ocular symptoms, this study demonstrated reduced ECD and HEX of corneal endothelial cells. The mean HEX was 46.52 ± 6.38 in the COVID-19 group versus 58.22 ± 13.94 in the control group. The patients who had COVID-19 demonstrated significantly lower ECD and HEX levels when compared to controls (p = 0.003 and p < 0.001, respectively). However, statistical significance was not achieved for the coefficient of variation and central corneal thickness. In this study, long-term corneal endothelial changes after COVID-19 infection were observed.

COVID-19 may lead to long-term changes in corneal endothelial cells, resulting in reduced ECD and HEX. Additional studies should focus on the prolonged effects of COVID-19 on the health of the cornea and visual outcomes.

Reference(s):

1. Fadel D, Kramer E. Potential contraindications to scleral lens wear. Cont Lens Anterior Eye. 2019 Feb;42:92-103.
2. Kılıçarslan O, Yılmaz Çebi A, Doğan C, Arslan OS. Long-Term Corneal Endothelial Parameters of COVID-19 Patients With Ocular Surface Symptoms. Cornea. 2024 Sep 1;43:1124-1127.
3. Erdem S, Karahan M, Ava S, Dursun ME, Hazar L, Keklikci U. Examination of the effects of COVID 19 on corneal endothelium. Graefes Arch Clin Exp Ophthalmol. 2021 Aug;259:2295-2300.
4. Oren B, Kocabas DO. Assessment of corneal endothelial cell morphology and anterior segment parameters in COVID-19. Ther Adv Ophthalmol. 2022 May 9;14:25158414221096057.

Melissa Barnett, OD, FAAO, FSLS is the director of optometry at the University of California, Davis. She has received remuneration from ABB, Acculens, Abbvie, Azura, Bausch + Lomb, BCLA, Bruder, Bruno Vision Care, CooperVision, Dompé, Epion, JJVC Vistakon, Lentechs, Ocusoft, Orasis, RVL Pharmaceuticals, Sight Sciences, Science Based Health, STAPLE Program, Sun Pharma, Taursus, and Visus.