Background/Purpose

Due to a variety of factors it is challenging to make a definite diagnosis in the early stages of Sjögren’s syndrome (SS). The ocular examination, including fluorescein and tear break-up time (TBUT), have been a critical part of the diagnosis algorithm. Limitations of these techniques are their relative invasiveness and lack of specificity. They can also have intrinsic toxicity, including cellular morphologic changes, including loss of cellular motility, cell detachment and death. We propose ocular surface temperature (OST) measurements as a novel, non-invasive technique that can potentially overcome these limitations.

Methods

We evaluated 5 subjects with SS that fulfilled American European Consensus Group criteria (AECG SS), 5 subjects with early disease (early SS), and 5 healthy controls (HCs). The early SS was defined as presence of autoantibodies suggestive of SS, ocular dryness less than 5 years, not fulfilling the AECG criteria. OST measurements were taken on both eyes over a 5 second interval, 30 measurements per second. In addition, tear film break-up time (TBUT), Schirmer, and fluorescein staining scores were obtained for each patient and each eye. For the early SS and AECG SS subjects we also obtained SF36, visual analog scale (VAS) for dryness, ESSDAI (EULAR SS Disease Activity Index) and standard of care laboratory analysis.

For each patient, the OST measurements from both eyes were averaged to create a single observation for each individual. Receiver operating characteristic (ROC) curves were fit using the different potential metrics under two different classification scenarios: HC vs early SS and SS, and SS vs HC and early SS. 

Results

Clinically, subjects with early SS had a lower SF36, VAS, ESSDAI, ESR, CRP, ANA and anti-Ro titers, and lower IgG compared with AECG SS. They also had a higher WBCs and complement levels. Although none of these differences reached statistical significance, they are suggesting that subjects with early SS had less active immunological disease and less subjective dryness than subjects with AECG SS.

An exponential transformation on OST and a log transformation on TIME produced an approximately linear relationship. The interaction was found to be statistically significant (p < 0.0001). This interaction indicates that early SS had a significantly less negative slope than the other two groups. The slope of the transformed linear relationship appeared to be the best metric for classifying AECG SS vs HC and early SS. 

Conclusion

Using OST we showed that subjects with early SS had a slower fall in their ocular temperature (indicative of less dryness) than patients with AECG SS and clearly separated from HCs. The ocular temperature measured at each second correlated best with the tear break up time (TBUT), suggesting that it could be used in conjunction with standard of care ocular dryness measurement, potentially improving the sensitivity of ocular measurements. Although the clinical characteristics of the AECG SS vs. early SS did not reach statistical significance, the trends suggested that early SS had less dryness, and less actively immunological disease (lower level of autoantibodies, lower inflammatory markers and IgG level), consistent with early disease.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/ocular-surface-temperature-in-early-sjogrens-syndrome-and-established-disease/