Eyelid, Periorbital, and Ocular Surface Temperature Differences Between Sjögren’s Eyes and Asymptomatic Controls Holly B. Hindman 1,2, Christine Callan 1,2, Ranjini Kottaiyan 1,2, Kerstin Abreau 3, Aizhong Zhang 4,5, James Aquavella 1,2, James Zavislan 4,5 1 Flaum Eye Institute, 2 University of Rochester, 3 Juniata College, 4 Center for Visual Science, 5 Institute of Optics

Background Sjögren’s Syndrome (SS) is an autoimmune mediated inflammatory disorder characterized by dry eyes and mouth. Infrared (IR) thermography is promising technology for ocular surface investigations as it is non-invasive and has high accuracy. IR imaging has been previously used to differentiate dry and normal eyes on the basis of ocular surface temperatures. 1, 2 Prior work in our laboratory has demonstrated that subjects with Sjögren’s Syndrome experience increased cooling of their ocular surfaces over an interblink interval. 3 The current study also compared eyelid and periorbital skin temperatures between SS and healthy control subjects to determine if the temperatures of the surrounding tissues are also relevant in understanding ocular surface temperature differences between these groups. 4

Purpose To compare the ocular surface, eyelid, and periorbital skin temperatures in subjects affected by dry eye resulting from Sjögren’s Syndrome with healthy controls within a controlled environmental chamber.

Methods Subjects: Data were collected from 10 subjects (20 eyes) with SS, and 10 age-matched, asymptomatic, control subjects (20 eyes). All patients included in the SS group fulfilled the AECG criteria for classification of SS. 5 The control group was comprised of patients that reported no subjective dry eye symptoms, and had no previous diagnosis of SS. Methods: Measurements were taken in a climate controlled chamber, with standardized conditions set to 75º F and 40% RH. Images were taken over 5-second blink intervals using an infrared thermal camera (Thermovision SC325, FLIR System). Post-image processing was completed utilizing custom written Matlab code (Mathworks, Inc.).

Methods (continued) Three locations for each data set were analyzed: Ocular surface: central (1), nasal, (2) and temporal (3) (Fig. 1a) Eyelid: central (1), nasal (2), and temporal upper lid (3) (Fig. 1b) Periorbital skin: superonasal (1), inferonasal (2), and inferotemporal orbital rim (3) (Fig. 1c) Temperature values were averaged over each region. Statistical analyses were performed using t-tests. Fig 1. Position of regions for analysis for ocular surface (a), eyelid (b), and periorbital skin (c). All regions were 3.6 or 5.4* mm in diameter (* a1, b1). a.b.c.

Results Qualitative differences in temperature were observed between normal control eyes and Sjögren’s eyes Fig. 2. Representative infrared images of control eyes and Sjögren’s eyes demonstrating qualitative show differences in ocular and skin temperatures compared to controls. (a) eye closed (b) eye open

Results Sjögren’s syndrome (SS) eyes have cooler mean OST & eyelid temperatures Fig 3. Mean Ocular Surface Temperatures (OST) of the 1) central cornea 2) nasal conjunctiva and 3) temporal conjunctiva of Sjögren’s and normal eyes. The mean OSTs of SS are significantly cooler than those of controls in the central corneal, nasal conjunctival, and temporal conjunctival regions (p-value < 0.01). Fig 4. Temperatures 1) central 2) nasal, and 3) temporal upper eyelid in Sjögren’s and normal eyes. The central (1) and nasal (2) eyelid regions were found to be cooler in SS (p- value < 0.01). No temperature differences were found in the temporal (3) eyelid region. * * * * *

Results Periorbital skin temperatures differ between Sjögren’s and controls Fig 5. Periorbital Temperatures of Sjögren’s eyes and normal controls over 1) superonasal orbital rim, 2) the inferonasal orbital rim, 3) the inferotemporal orbital rim. The two nasal orbital rim regions (1&2) were found to be warmer (p-value < 0.01) in SS than those of controls while the inferotemporal orbital rim (3) was found to be cooler in SS (p- value < 0.01). * * *

Supplemental Graphs Fig. 6. Time-segmented cooling rates of Sjögren’s eyes and normal controls demonstrate faster cooling rates particularly immediately after lid opening. Fig. 7. Ocular surface temperatures were cooler initially and cooled more rapidly in Sjögren’s eyes relative to normal controls

Discussion Our results are consistent with other reports in that Sjögren’s eyes hadcooler ocular surface temperatures and faster cooling rates relative to normal eyes. Our study also measured for the first time, the temperatures of the surrounding tissues and found that Sjögren’s eyes have cooler eyelids and other periorbital temperature differences from normals. Temperatures of the surrounding structures likely impact the ocular surface temperature (e.g. cooler eyelid temperatures provide a cooler “thermal pulse” 6 with each blink to the ocular surface which may account for the cooler OST upon eyelid opening of SS patients). Lid temperature may impact initial ocular surface temperature whereas the change in OST observed during the interblink period may be more affected by tear film evaporation. Additional research is needed to better understand the identified differences in temperature and their potential pathophysiologic underpinnings.

Conclusion In this study we have demonstrated significant differences in lid and periorbital temperatures between Sjögren’s syndrome eyes and age-matched normal controls. Given the transfer of heat by conduction and proximity of these tissues to the ocular surface, the temperature differences in the lids and periorbital likely play an important role in the initial ocular surface temperature differences identified.

Acknowledgements: Funding was provided by: RPB, CVS training grant T32 EY No Financial Disclosures References: 1 Azharuddin M, et al. Thermal fluctuation based study of aqueous deficient dry eyes by non-invasive thermal imaging. Exp Eye Res. 2014;120: Kottaiyan R, et al. Integrated Multimodal Metrology for Objective and Noninvasive Tear Evaluation. Ocul Surf. 2012; 10: Kottaiyan R, et al. Tear Dynamic Measurements in the Differentiation of Sjogren’s Dry Eye from Non-Sjogren’s Dry Eye. ARVO Chang, Hsiao, & Liao. Application of digital infrared thermal imaging in determining inflammatory state and follow-up effect of methyprednisolone pulse therapy in patients with Grave’s opthalmopathy. Graefes Arch Clin Opthalmol 2007;246: Goules AV, et al. Classification criteria of Sjögren's syndrome. J Autoimmun. 2014; 48-49; Zhang, Aizhong. Thermal analysis of dry eye subjects and the thermal impulse perturbation model of ocular surface. Manuscript submitted for publication