Elevated Anti-Cyclic Citrullinated Peptide Levels Associated with Filamentary Keratitis

To assess two cases of filamentary keratitis with elevated serum levels of anti-cyclic citrullinated peptide (anti-CCP) antibodies without known rheumatoid arthritis (RA).

A retrospective chart review was conducted on cases with filamentary keratitis and elevated anti-CCP antibodies between January 2021 and January 2023. Patient demographics, clinical characteristics, and serological test results were reviewed.

The first patient, a 77-year-old man, presented with foreign body sensation and eye redness. He reported mild dry mouth but no joint pain or known autoimmune disease, though he had a family history of RA. Schirmer test scores were 7 and 12 mm in the right and left eyes, with an ocular staining score (OSS) of 12 in each eye. His serum anti-CCP antibody level was >2,777 U. Over 3 years of follow-up, he showed no signs of RA development. The second patient, an 84-year-old man, presented with severe burning and light sensitivity but no dry mouth or joint pain. Schirmer test scores were 2 and 3 mm in the right and left eyes, with OSS of 9 and 5, respectively. His serum anti-CCP level was 1330 U. He developed inflammatory arthritis and was diagnosed with RA 16 months after initial presentation.

This report suggests that filamentary keratitis with elevated serum anti-CCP antibody levels may indicate early RA. These findings underscore the importance of anti-CCP testing in filamentary keratitis patients, even without typical RA symptoms. Further research is needed to explore the link between anti-CCP antibodies and ocular surface diseases in RA.