Comparing the ocular surface temperature and dry eye condition of keratoconus with normal eyes using infrared thermal imaging

Purpose This study was conducted to compare the ocular surface temperature in keratoconus eyes with that in normal eyes. Methods A total of 27 participants were enrolled, with 10 and 17 participants in the keratoconus and control groups, respectively. Participants in the control group underwent an ophthalmic slit lamp examination and ocular thermography, while an additional corneal tomography was performed for those in the keratoconus group. Results For patients with keratoconus, the mean upper eyelid temperature (UET) was 32.36 ± 1.02 °C, inner canthus temperature (ICT) was 34.25 ± 0.83 °C, outer canthus temperature (OCT) was 33.62 ± 0.96 °C, initial central corneal temperature (initial CCT) was 33.04 ± 1.03 °C, sixth-second CCT (6 s-CCT) was 32.67 ± 1.19 °C, and the mean change in CCT measured within 6 s (change in CCT within 6 s) was 0.36 ± 0.26 °C. For controls, the values for UET, ICT, OCT, initial CCT, 6 s-CCT, and change in CCT within 6 s were 32.35 ± 1.13 °C, 34.14 ± 0.91 °C, 33.51 ± 1.02 °C, 33.22 ± 1.01 °C, 32.99 ± 1.01 °C, and 0.22 ± 0.17 °C, respectively. Except for the change in CCT within 6 s ( p = 0.022), no significant differences were observed in UET (p = 0.973), ICT ( p = 0.659), OCT ( p = 0.697), initial CCT (p = 0.556) or 6 s-CCT ( p = 0.310) between the two groups. Conclusion The keratoconus eyes showed faster changes in CCT and evaporation of tear film after opening the eyes. Therefore, the keratoconus eyes had a higher incidence of dry eye conditions.