The application of temperature measurement of the eyes by digital infrared thermal imaging as a prognostic factor of methylprednisolone pulse therapy for Graves’ ophthalmopathy

Abstract

Graves' ophthalmopathy (GO) involves autoimmune process resulting in proptosis, congestion, oedema and diplopia. Werner's NOSPECS classification and clinical activity score (CAS) of GO cannot objectively describe the inflammatory status. Digital infrared thermal imaging (DITI) detects local temperature and may reflect the degree of orbital inflammation. The aim of this study was to evaluate the clinical application of the eye temperature measured by DITI. Forty-six patients with GO receiving intravenously methylprednisolone pulse therapy (MPT) were included in this study. Local temperatures of the lateral orbit, upper eyelid, inner caruncle, medial conjunctiva, lateral conjunctiva, lower eyelid and cornea were measured with DITI before and after MPT. CAS, proptosis, eye movement (EOM) and diplopia were also recorded. Improvement of CAS was defined as at least one point decrease at either side of the eye, which was 0.5 score decrease as to the average of bilateral CAS. Local temperatures of the eyes decreased after MPT. The mean value of temperature (MT) of 12 points including the lateral orbit, upper eyelid, inner caruncle, medial conjunctiva, lateral conjunctiva and lower eyelid of both eyes before MPT was 32.65 degrees . The mean change of MT after MPT (DeltaT) was -0.22 degrees. DeltaT significantly negative-correlated with basal MT (correlation coefficient=-0.54, p=0.004). Higher baseline MT and CAS before MPT correlated with higher possibility of improvement of CAS after MPT (p=0.013 and 0.012, respectively). Baseline MT and CAS together correlated with improvement of CAS after MPT better than baseline CAS alone could do (area under the receiver operating characteristic curve: 82.81% and 66.63%, respectively). Basal temperature of the eyes measured by DITI was an objective indicator of inflammation of GO. Combining CAS and MT could better predict the outcome of MPT than CAS alone.