Ocular Surface Disease Index and Ocular Thermography in Keratoconus Patients

Purpose. Keratoconus (KC) has been defined as a "noninflammatory" corneal disease, but recent studies have noted a potential inflammatory origin. We analysed the Ocular Surface Disease Index (OSDI) and ocular surface temperature (OST) in KC patients compared to controls. Patients and Methods. A total of 179 eyes in 90 patients with KC (topographic keratoconus classification 0-1 to 4, age 36.1 ± 12.5 years, 65.9% males) and 82 eyes in 41 controls (age 36.4 ± 12.8 years, 47.6% males) were examined. The participants completed the OSDI questionnaire and underwent corneal topography, tomography, and thermography. Additional outcome measures were vision- and discomfort-related OSDI subscores and mean OST at the corneal centre during 10 seconds of sustained eye opening after blinking. Results. The OSDI score (31.4 ± 22.4 vs. 17.5 ± 17.9) and vision- (17.7 ± 14.6 vs. 10.5 ± 13.2) and discomfort-related (14.3 ± 10.7 vs. 9.4 ± 10.5) OSDI subscores were significantly higher in KC patients than in controls (p<0.001). We found no significant difference in the central corneal OST (34.2 ± 0.6°C vs. 34.2 ± 0.7°C; p=0.41) between the two groups (p≥0.22). The OSDI score and subscores poorly to fairly correlated with the surface asymmetry index (SAI) and surface regularity index (SRI; r > 0.174, p<0.005), but did not correlate with the central corneal OST (r < 0.001). OST also did not correlate with the SAI, SRI, and central corneal thickness (r ≥ -0.086). Conclusion. KC patients had increased OSDI scores and vision- and discomfort-related OSDI subscores without an increase in the OST compared to a normal population. OSDI score/subscores weakly correlate with SAI and SRI but do not correlate with OST in KC patients or controls. Vision- and discomfort-related symptoms of KC have to be managed in parallel in ophthalmological practice, but the necessity of anti-inflammatory treatment cannot be verified through ocular thermography. © 2020 Orsolya Németh et al.