Aim: To investigate microscopic changes in corneal morphology in chloroquine (CQ)-treated patients without corneal abnormalities being diagnosable by slit lamp microscopy.
Methods: Thirty-six eyes of 36 patients with rheumatoid arthritis (RA) were divided into two groups: group 1 included 26 patients receiving chloroquine therapy; group 2 included the other 10 patients, not receiving chloroquine therapy. The control group included 15 healthy subjects. Best spectacle-corrected visual acuity (BSCVA), intraocular pressure (IOP) and slit lamp microscopy and in vivo confocal microscopy examinations were performed on all subjects.
Results: In group 1, hyperreflective abnormal particles were found in different layers of the cornea in 19 (75%) of 26 eyes by confocal microscopy. The deposits were present within the superficial epithelium (14/19), basal epithelium (8/19) and anterior stroma (5/19). In both RA groups, more beaded and tortuous fibers were seen in the sub-basal corneal nerve bundles, and the sub-epithelial and stromal nerves had much more branches, than did normal controls. The anterior keratocyte density in group 1 was lower than in group 2 (P < 0.05) and the number of sub-basal nerves was larger than in group 2 (P < 0.05). Cumulative dosage had a statistically significant correlation with anterior keratocyte density, the number of sub-basal nerves and the density of abnormal particles.
Conclusion: Corneal microdeposits are an important manifestation of chloroquine-induced keratopathy. Corneal stroma cell density and corneal nerve number and morphology changes are also useful for detecting early chloroquine-induced keratopathy. This would be proved in our future longitudinal studies.