Ocular thermography in keratoconus

AbstractKeratoconus (KC) is defined as a non‐inflammatory corneal disease, however, recent studies discuss a potential inflammatory origin. 251 eyes of 132 patients with KC (TKC ‘0‐1’ to ‘4’; age 37.1 ± 13.2 years, 65.7% males) and 75 eyes of 39 healthy subjects (TKC ‘‐’, age 35.4 ± 12.8 years, 43.6% males) were examined. KC was diagnosted using slitlamp examination and corneal topo‐ (TMS‐5, Tomey, Erlangen‐Tennenlohe, Germany) and tomography (Pentacam, Wetzlar, Germany). The patients filled the Ocular Surface Disease Index (OSDI) questionnaire (score ranges for normal 0–12; mild 13–22; moderate 23–32; severe 33–100 ocular surface disease) and were examined by the Ocular Surface Thermographer TG‐1000 (Tomey, Erlangen‐Tennenlohe, Germany). Main outcome measures beside OSDI were mean corneal surface temperature (CST) at the center and 2 mms from the center nasally, temporally, superiorly and inferiorly, during 10 seconds of sustained eye opening, after blinking.OSDI Score was significantly higher in KC (30.4 ± 21.5) as in normal subjects (14.6 ± 15.3) (p < 0.001). There was no significant difference in central (34.2 ± 0.6 vs 34.2 ± 0.6), nasal (34.2 ± 0.6 vs 34.1 ± 0.6), temporal (34.1 ± 0.6 vs 34.2 ± 0.6) and superior (34.1 ± 0.6 vs 34.1 ± 0.6) CST between both groups (p > 0.75). OSDI Score was correlated with surface asymmetry index (SAI) and surface regularity index (SRI) of topographer and with TKC of tomographer (p < 0.006), however did not correlate with CST at the corneal center (p = 0.80). CST at corneal center was also not correlated with SAI, SRI and TKC (p > 0.18).An increased OSDI Score may refer to corneal surface irregularity in KC, which is not accompanied by an increased CST. Further studies are necessary to clarify the potential inflammatory origin of KC.