Patients with a previously confirmed COVID-19 infection had significantly higher corneal and lenticular densitometric values compared with patients without a prior COVID-19 diagnosis, according to a prospective, cross-sectional study.

“In addition to the determination of conjunctival abnormalities, the virus was also found to be present in both tears and conjunctival swab specimens,” Emre Aydemir, MD, of the ophthalmology department at Adiyaman Training and Research Hospital in Turkey, and colleagues wrote in Optometry and Vision Science.

“Further investigations have found viral RNA present in the retinas of COVID-19 patients, as well as various other retinal findings. Cheema et al. reported a keratoconjunctivitis case in a COVID-19 patient presenting with subepithelial infiltrates and dendritic lesions. Despite these reports, research on the effects of the virus on the anterior segment structures such as the cornea and lens is limited.”

Aydemir and colleagues analyzed data on 53 patients who had recovered from lab-confirmed COVID-19 and 51 control patients who had not had COVID-19, matching participants by age and sex. Participants were excluded for previous or current ocular conditions, including keratoconus, contact lens use and ocular trauma, as well as drug use, smoking or alcohol use.

Using a Pentacam HR Scheimpflug imaging system, researchers measured corneal densitometry at the anterior, central and posterior layers and in four concentric zones: diameters of 0 to 2 mm, 2 to 6 mm, 6 to 10 mm and 10 to 12 mm. Lenticular densitometric values were calculated from the center of the pupil at 2 mm (zone 1), 4 mm (zone 2) and 6 mm (zone 3).

Corneal densitometry was significantly higher in the COVID-19 group compared with the control group for the anterior 0 to 2 mm, 2 to 6 mm and 6 to 10 mm zones and total diameter; the central 0 to 2 mm and 2 to 6 mm zones and total diameter; the posterior 0 to 2 mm zone; and the total 0 to 2 mm and 2 to 6 mm zones and total diameter. The other zones also were higher in the COVID-19 group, but those values did not reach significance.

“The differences we found between COVID-19 and control patients in values related to corneal densitometry suggest that there may be a global impact on the cornea, especially in the anterior layer and central zones,” Aydemir and colleagues wrote.

In addition, lenticular densitometric values, with the exception of zone 1, also were significantly higher in the COVID-19 group.

Although this was the first study to quantify corneal and lenticular transparency, the researchers conceded limitations including small sample size, cross-sectional design, examination of patients early in their recovery period and patient use of anticoagulants and antivirals. Future studies may address these issues, Aydemir and colleagues wrote.

“As the pandemic continues to unfold and affect a great number of people, it should be kept in mind that the inflammatory responses triggered by the virus can adversely affect cornea and lens transparency,” they concluded.