Abstract
Purpose:
To measure ocular surface temperature (OST) in mild-moderate dry eye (DE) patients and to correlate values with disease severity
Methods:
30 patients diagnosed as having mild-moderate DE according to DEWS guidelines (DEWS grade 1 and 2, 15 patients each) and 30 normal subjects were included in this prospective controlled study. Exclusion criteria were: history of atopy, allergic diseases, infectious surface diseases, chemical/thermal injury. Dynamic infrared non-contact thermal imaging (Tomey TG 1000, Nagoya, Japan; Emmeciquattro, Parma, Italy) was used to measure OST in 3 circular (4 mm diameter) regions: central cornea (CC), nasal conjunctiva (NC) and temporal conjunctiva (TC). The procedure was repeated 3 times during a single session by 2 examiners. OST was measured immediately after blinking at eye opening (T0) and after 10 second of sustained eye opening (T1); the difference between the two values (Δ) was calculated. Discomfort subjective symptoms were evaluated with OSDI questionnaire. Schirmer test I, Break up Time (BUT), Lissamine green vital staining, conjunctival scraping cytology and determination of exudated serum albumin in tears were performed in all subjects. OST and Δ values recorded in all regions were correlated (Pearson’s r) with the tests. Data were statistically evaluated by applying Student’s t test, Mann-Whitney and Wilcoxon’s tests, when appropriate, significance p<.05
Results:
OST measurements showed high reproducibility and repeatability (concordance coefficient 0.972 and 0.954, respectively). OST was higher in NC, followed by TC and CC, this one being the cooler region in all subjects. T0 was significantly lower in each region in DE patients as compared to controls (medium+SD respectively 34.01±0.76 vs 34.29±0.33 °C in CC; 35.01±0.6 vs 35.25±0.37 °C in NC; 34.20±0.71 vs 34.47±0.41 °C in TC). Δ values were found to be always significantly higher in DE patients vs controls, especially in CC (-0.25 vs -0.17 respectively). T0 in CC was found to be inversely correlated with OSDI score (r=-0.45), and DEWS grade (r=-0.42). Δ values in NC was found correlated with Lissamine score (r=-0.36) and with albumin concentration in tears (r=+0.43)
Conclusions:
OST in mild-moderate DE patients was demonstrated to be lower than in control subjects in all regions; OST also appeared to be inversely related to disease severity and subjective symptoms, mainly in the central cornea region
Keywords: 486 cornea: tears/tear film/dry eye •
474 conjunctiva •
550 imaging/image analysis: clinical