Contact lenses affect corneal thickness

Contact lenses negatively influence corneal physiology, according to a study conducted at an Istanbul medical school.

In 84 eyes of 45 patients, Baris Yeniad, MD, and colleagues found that both soft and rigid gas-permeable contact lenses caused both corneal thickening and thinning in different areas of the cornea within the first few months of wear. Contact lens wear was also linked to corneal flattening and steepening by the 1-year follow-up.

The investigators assigned the patients, who were first time contact lens wearers, to one of three groups based on the duration of wear: 1 month, 6 months and 1 year. They also divided the patients into two subgroups according to the type of contact lens, rigid or soft.

The patients, who ranged in age from 15 to 44, achieved a mean visual acuity of 0.92 ± 0.26 with their contact lenses. In comparison, their best corrected visual acuity with spectacles was 0.82 ± of 0.26.

Investigators noted that corneal thickening began within 1 month when compared to nine measurements of corneal thickness and topography recorded at baseline. At 6 months, patients with soft contact lenses experienced corneal thinning in all regions; patients with gas-permeable lenses experienced thinning in all regions except the inferior temporal region.

At 1 year, investigators noted corneal thinning in all regions except the inferior nasal region in soft lens wearers, and in all regions except the central region in gas-permeable lens wearers.

They also observed corneal flattening at months 1 and 6 as well as corneal steepening at 1 year.

The study appears in Eye & Contact Lens: Science and Clinical Practice.