Abstract
Purpose: :
To assess typical ocular thermal symmetry in a group of control subjects, and to observe whether inter-ocular asymmetry in selected subjects appears related to the presence of pathology of the ocular surface or adnexa.
Methods: :
A portable infra-red camera (ThermoVision A40M, Flir) was used to record asymmetry in ocular and peri-orbital skin surface temperature in 49 healthy control subjects (19M, 30F; mean age 41.3±18.2yrs), and in 22 symptomatic patients (14M, 8F; mean age 44.1±19.7yrs) attending a hospital emergency department. Statistical comparisons using paired t-tests and confidence intervals were applied between controls and groups of pathology, and cases of isolated pathology were also observed.
Results: :
In control subjects, the mean temperature difference between corneae was 0.06±0.23°C (95% CI -0.005 to 0.13°C; p=0.07), and typical peri-orbital asymmetry was 0.09±0.19°C (95% CI 0.04 to 0.15°C; p<0.05). There was no significant thermal asymmetry between symmetrical points on the face (0.05±0.42°C (95% CI -0.07 to 0.17°C; p=0.41). The effect of age (0.07<p<0.52) and gender (0.29<p<0.94) on thermal asymmetry in control subjects was statistically insignificant. Subjects with chalazia (n=10) showed significant thermal asymmetry between eyelids: mean difference +0.54±0.33°C (95% CI 0.19 to 0.88°C; p<0.05). Ocular surface temperature overlying corneal abrasions (n=6) increased by +0.70±0.31°C (95% CI 0.37 to 1.02°C; p<0.005), whereas in cases of acute corneal ulceration (n=3) average thermal difference between corneae was -2.39±0.83°C (95% CI -4.45 to -0.32°C; p<0.05), with the affected eye exhibiting the reduced temperature. Where an inflammation of the iris, sclera or conjunctiva was present, the overlying increase in temperature varied from +1.52 to +3.66°C, compared with the fellow eye in individuals (n=3).
Keywords: imaging/image analysis: clinical • anterior segment • eyelid