Findings from a recent study published in Cornea evaluated the long-term effects of coronavirus disease 2019 (COVID-19) on corneal endothelial cell morphology in patients with ocular symptoms to investigate possible corneal involvement in recovered patients.
Give me some background.
COVID-19 is caused by the highly contagious SARS-CoV-2 RNA virus and can present with ocular manifestations such as epiphora, conjunctival congestion, and photophobia.
Previous studies have demonstrated that during the early period of disease, COVID-19 causes a decrease in the number of corneal endothelial cells and hexagonal cells and an increase in the coefficient of variation and central corneal thickness (CCT) in individuals recovering from the infection.
Go on …
Specular microscopy allows for the evaluation of endothelial cell morphology and corneal pachymetry, allowing researchers to develop insights into endothelial cell involvement in various diseases.
- Consequently: The investigators sought to elucidate the long-term impact of COVID-19 on the cornea in recovered patients.
Talk about the study.
In this retrospective, cross-sectional study, investigators included participants in the COVID-19 group who were diagnosed and treated at Istanbul University Cerrahpasa Medical Faculty with polymerase chain reaction (PCR)-confirmed SARS-CoV-2 infection and ocular irritation symptoms.
The control group was made up of age- and sex-matched individuals with no ocular pathologies.
How did they assess corneal cell morphology?
Noncontact specular microscopy was performed using the center method after 156 ± 16 days of COVID-19 diagnosis.
Researchers investigated corneal parameters, such as:
- Endothelial cell density (ECD)
- Hexagonality (HEX)
- HEX is an indicator of corneal endothelial cell uniformity and health
- Lower values potentially demonstrate compromised cell morphology
- A normal cornea is expected to have around 60% HEX
- HEX is an indicator of corneal endothelial cell uniformity and health
- Coefficient of variation
- CCT
Findings?
The study included the specular microscopy results of 54 COVID-19 patients with ocular irritation symptoms and 72 controls in the analyses.
Ocular symptoms in COVID-19 patients included:
- Conjunctival hyperemia
- Foreign body sensation
- Tearing
- Ocular sensation
- Chemosis
How did COVID-19 patients differ from the controls?
The investigators found significantly lower mean (standard deviation [SD]) ECD and HEX levels in the COVID-19 group:
- ECD (P = 0.003)
- COVID-19 group: 2,770 ±31 cells/mm2
- Control group: 2,897 ± 26 cells/mm2
- HEX (P < 0.001)
- COVID-19 group: 46.52% ± 6.38
- Control group: 58.22% ± 13.94
In addition: The coefficient of variation and CCT analyses did not reach statistical significance.
Expert opinion?
These findings and previous case reports on acute graft rejection during COVID-19 infection indicate that “corneal donors with COVID-19 history should be carefully investigated because they may be at high risk of donor rejection or endothelial decompensation,” the study authors noted.
Limitations?
These included:
- Due to risk of contamination, eye examinations were not performed during the active COVID-19 period.
- Patients were included based on self-reported subjective and nonspecific symptoms.
- Patients had ocular surface symptoms, but they performed no conjunctival PCR testing for SARS-CoV-2—as such, it could not be ensured that symptoms were directly linked to COVID-19 itself.
- However, the COVID-19 diagnosis was PCR-proven in all cases, so new-onset ocular symptoms were believed to be associated with COVID-19.
Take home.
These findings suggest that COVID-19 infection can cause long-term alterations to corneal endothelial cells, leading to decreased ECD and impaired endothelial cell morphology.
Future studies should focus on the long-term implications of COVID-19 on corneal health and visual outcomes.