To investigate microscopic changes in corneal morphology in chloroquine (CQ)-treated patients without corneal abnormalities being diagnosable by slit lamp microscopy.
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.
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.
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.