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Ankit M Shah,1 Anat Galor1,2 1Bascom Palmer Eye Institute, University of Miami, Miami, FL, USA; 2Surgical Services, Miami Veterans Affairs (VA) Medical Center, Miami, FL, USACorrespondence: Anat GalorBascom Palmer Eye Institute, 900 NW 17th St, Miami, FL, 33136, USAEmail agalor@med.miami.eduAbstract: Infrared (IR) thermographic assessment of ocular surface temperature (OST) is gaining interest as an adjuvant method to evaluate the ocular surface. It is a quick, non-invasive test that causes minimal, if any, discomfort to patients. The purpose of this article was to summarize research on how OST relates to tear film parameters and dry eye disease (DED). PubMed, Google Scholar, and Scopus searches for specific terms were carried out and eligible articles reviewed. OST of the central cornea is ∼ 34-35°C when measured as a single time-point (typically right after a blink). Dynamically, OST values decrease over time at a rate of ∼ − 0.01 °C/s in healthy eyes. Single time-point OST values are impacted by temperature, with positive correlations noted with both ambient (1°C↓ results in ∼ 0.16°C↓ in OST) and body (1°C↑ results in ∼ 0.98°C↑ in OST) temperature. Single time-point OST values are also impacted by tear parameters, with negative correlations noted with tear break-up time (TBUT; r=− 0.61) and positive correlations with lipid layer thickness (∼r=0.50). Dynamically, the rate of OST cooling over the interblink period correlates with various tear parameters including Schirmer’s test scores (r=− 0.39), tear meniscus height (r=− 0.52) and the rate of tear film break-up (r=− 0.74). These data imply that OST decreases more rapidly in individuals with greater tear production, larger tear volumes, and shorter tear break-up times (faster rates of tear film break-up). There are discrepancies in relationships between OST and DED across studies, which is not surprising given that DED encompasses a number of different phenotypic presentations. However, most studies found that OST decreases at a more rapid rate in DED vs. control groups. As such, cooling rate may have utility as a screening tool in DED in combination with established point-of-care tests.Keywords: ocular thermography, tear film, dry eye

Corneal transplant rejection is one of the most frequent complications, with a reported incidence of 16–30%. In our current research, we investigated the use of infrared thermography to detect ocular surface temperature. We also looked at a case of corneal transplant rejection and this case had an elevated ocular surface temperature when compared to the contralateral eye and other eyes without corneal transplant rejection. Twenty-three eyes of twelve patients would serve as control to one eye with clinically evident corneal transplant graft rejection. A Flir T400 320 × 240 pixel, digital thermal camera was used to take a digital photograph and an infrared photograph of each eye. The images were analyzed with the Flir web viewer. We present here a case of corneal transplant rejection documented with both slit lamp photos as well as infrared and corneal surface photos. The studied patient’s unaffected eye, and the control group’s trends did indeed bring the expected results and proved thermal imagery in this particular field a viable examination method. We feel that ocular thermography is a useful adjunctive diagnostic tool and that it may be useful to monitor routine corneal transplant patients. Further research into the temperature changes of corneal transplant patients is needed and may allow for earlier intervention for graft rejection.

Imaging has become indispensable in the diagnosis and management of diseases in the posterior part of the eye. In recent years, imaging techniques for the anterior segment are also gaining importance and are nowadays routinely used in clinical practice. Ocular surface disease is often synonymous with dry eye disease, but also refers to other conditions of the ocular surface, such as Meibomian gland dysfunction or keratitis and conjunctivitis with different underlying causes, i.e., allergies or infections. Therefore, correct differential diagnosis and treatment of ocular surface diseases is crucial, for which imaging can be a helpful tool. A variety of imaging techniques have been introduced to study the ocular surface, such as anterior segment optical coherence tomography, in vivo confocal microscopy, or non-contact meibography. The present review provides an overview on how these techniques can be used in the diagnosis and management of ocular surface disease and compares them to clinical standard methods such as slit lamp examination or staining of the cornea or conjunctiva. Although being more cost-intensive in the short term, in the long term, the use of ocular imaging can lead to more individualized diagnoses and treatment decisions, which in turn are beneficial for affected patients as well as for the healthcare system. In addition, imaging is more objective and provides good documentation, leading to an improvement in patient follow-up and education. Published version This research was funded by the Medical Scientific Fund of the Mayor of the City of Vienna, Project No. 17059.

The focus of this research is the investigation of the Ocular Surface Temperature (OST) in both healthy and pathological (e.g. age-related macular degeneration, eye dry syndrome and choroidal lesions) eyes by using Infrared Thermography (IR). Specifically, the temperature of different anatomical areas (or points) of the eye is measured by applying image processing procedures on the infrared images recorded. It is known that the pathogenesis of some ocular pathology is related to the variation of ocular blood perfusion, and thus to the temperatures of the anterior segment of the eye. Results demonstrated that thermography can provide quantitative documentation of these temperature measurements. Furthermore, thermography is a non-invasive, cheap, harmless and portable technique. The challenge is to make ocular thermography part of the daily diagnostic procedure by providing more and more reliable experimental data.

Obstructive meibomian gland dysfunction (MGD) frequently induces a chronic complaint with various symptoms related to dry eye and discomfort. Previous research indicates a pivotal role for heat therapy for melting the meibum as part of any successful management plan, but delivery of constant temperature during treatment is vital. This study evaluated the performance of a novel device designed to deliver controlled, latent, moist heat to the eyelids and surrounding area.The signs, symptoms and ocular temperature of 25 normal subjects (M8, F17; age 29.2±5.7 years) were recorded before and after a 10min application of the Blephasteam(®) device. Ocular temperature (non-invasive ocular thermography; A40 Flir, UK), tear film stability (NIBUT), intra-ocular pressure (IOP), and ocular surface staining and hyperaemia were recorded. Results were checked for normality and compared using paired t-tests.Temperatures in both eyelids were significantly greater after device application (upper +1.7±0.9°C; lower +2.1±0.7°C, p0.0005). Bulbar conjunctival hyperaemia significantly decreased after treatment (p0.005), but limbal and palpebral hyperaemia remained similar (p=0.33 and p=0.11, respectively). Ocular surface staining (p=0.74) and tear film stability (p=0.12) were unchanged in this normal cohort, and there was no significant change in IOP (13.8±2.0mmHg vs 12.9±2.2mmHg; p=0.092).The Blephasteam(®) device provides effective levels of warming that would be sufficient to melt meibum, and no adverse ocular responses were recorded in this cohort, indicating that this is a safe device. Interestingly, even in this normal cohort, ocular surface redness appears less after treatment.

Infrared thermography was used to measure temperature differences of the corneal surface between nasal and temporal limbus regions and central cornea of normal dogs and dogs with keratoconjunctivitis sicca (KCS), in order to establish temperature values in normal canine eyes and in patients with decreased Schirmer tear tests (STT) values. Dogs investigated were all either patients seen at the Veterinary Teaching Hospital of Federal University of Parana or normal dogs that belonged to the same institution. STT were performed in all eyes. A total of 40 control eyes (STT ≥15 mm/min) and 20 eyes with low STT values (STT ≤14 mm/min) were examined. The mean STT value for eyes with normal STT values was 22.9 ± 3.9 mm/min (mean ± standard deviation), and the mean STT value for eyes with low STT value was 7.2 ± 4.8 mm/min. The mean corneal temperature was significantly lower in eyes with low STT values than in control eyes (P < 0.0001). The following significant correlations were found: (i) Schirmer and breakup time (BUT) (P = 0.0001, r = 0.5); (ii) STT values and corneal surface temperature (P = 0.001, r = 0.256); (iii) STT values and age (P = 0.0001, r = -0.448); (iv) age and corneal surface temperature (P = 0.0001, r = -0.281); and (v) BUT and corneal surface temperature (P = 0.0001, r = 0.36). Thermography is a method that can differentiate between eyes with normal and abnormal STT values. In the future, thermography might be incorporated as part of the ophthalmic examination and perhaps become a popular ancillary test for the diagnoses of ocular surface disorders.

Objective In recent decades infrared thermography (IRT) has facilitated accurate quantitative measurements of the ocular surface temperature (OST), applying a non-invasive procedure. The objective of this work was to develop a procedure based on IRT, which allows characterizing of the cooling of the ocular surface of patients suffering from dry eye syndrome, and distinguishing among patients suffering from aqueous deficient dry eye (ADDE) and evaporative dry eyes (EDE). Approach All patients examined (34 females and 4 males, 23-84 years) were divided into two groups according to their Schirmer I result (⩽ 7 mm for ADDE and > 7 mm for EDE), and the OST was recorded for 7 s at 30 Hz. For each acquisition, the temperatures of the central cornea (CC) as well as those of both temporal and nasal canthi were investigated. Main results Findings showed that the maximum temperature variation (up to 0.75 ± 0.29 °C) was at the CC for both groups. Furthermore, patients suffering from EDE tended to have a higher initial OST than those with ADDE, explained by the greater quantity of the tear film, evenly distributed over the entire ocular surface, keeping the OST higher initially. Results also showed that EDE patients had an average cooling rate higher than those suffering from ADDE, confirming the excessive evaporation of the tear film. Significance Ocular thermography paves the way to become an effective tool for differentiating between the two different etiologies of dry eye syndrome.

In this paper we propose a methodology for early detection and recognition of Glaucoma in ocular thermographs. Ocular thermography is an efficient tool not only to capture temperatures of corneal surface, but also to detect and visualize any changes on the Ocular surface temperature. The proposed method uses a linear transformation for pre-processing. Logistic Regression based classifier with the features collected from GLCM is used to classify the given ocular IR thermal image into Glaucoma from the normal eye. The efficacy of the proposed technique is proved over a number of ocular thermal image samples.

This review summarizes basic research in orbital and oculoplastic surgery during the past year. Innovative and exciting projects have been undertaken elucidating microscopic anatomy of the orbital septum, orbital lymphatics, and levator elastic fiber network. Eyelid anatomy as assessed by magnetic resonance imaging has been beautifully demonstrated. In the realm of orbital disease, several studies have provided potential alternative therapeutic modalities in the management of the anophthalmic socket. These particular studies range from the use of demineralized bone in the rabbit anophthalmic socket, to the use of bone graft to reconstruct the monkey orbital floor. Further elegant studies outline the velocity of ophthalmic artery flow, and potential applications of ocular thermography.

Thermography is an investigative technique which allows rapid color-coded display of the temperature across a wide surface by means of infrared detection. We describe an ocular thermographic study of a normal population and present case studies describing the application of this technique for patients with ocular disease. We found that 95% of the normal population have an interocular temperature difference (temperature of center of right cornea minus temperature of center of left cornea) of 0.60 degrees or less. There appears to be a greater difference in temperature between the limbus and the center of the cornea in patients with dry eyes. This technique has potential for evaluating tear film disorders and inflammatory conditions, for monitoring the progress of such conditions, and for evaluating the efficacy of various treatments.

Purpose Heat therapy is the standard treatment regime for obstructive meibomian gland dysfunction (MGD). Research has shown the melting point of the meibum is raised to 35C in MGD compared to 32C in normal subjects, and sustained heat delivery is essential in effective treatments. This study was designed to evaluate the changes in ocular surface signs and temperature efficacy of a novel device which delivers latent moist heat to the eye lids and surrounding area for 10 minutes. Methods A prospective, controlled, single intervention trial recruited 25 normal subjects (M8, F17; age 29.2±5.7yrs). Ocular temperature, tear film stability, ocular hyperaemia and surface staining were measured, using non-invasive ocular thermography and Efron grading respectively,, before and after device application. Results were checked for normality and compared using paired t-testing. Results Temperature significantly increased to effective levels in both the upper (37.7±0.58C; p

PURPOSE. To examine the relation between ocular surface temperature (OST) assessed by dynamic thermal imaging and physical parameters of the anterior eye in normal subjects. METHODS. Dynamic ocular thermography (ThermoTracer 7102MX) was used to record body temperature and continuous ocular surface temperature for 8 s after a blink in the right eyes of 25 subjects. Corneal thickness, corneal curvature, and anterior chamber depth (ACD) were assessed using Orbscan II; noninvasive tear break-up time (NIBUT) was assessed using the tearscope; slit lamp photography was used to record tear meniscus height (TMH) and objective bulbar redness. RESULTS. Initial OST after a blink was significantly correlated only with body temperature (r = 0.80, p < 0.0005), NIBUT (r = -0.68, p < 0.005) and corneal curvature (r = -0.40, p = 0.05). A regression model containing all the variables accounted for 70% (p = 0.002) of the variance in OST, of which NIBUT (29%, p = 0.004), and body temperature (18%, p = 0.005) contributed significantly. CONCLUSIONS. The results support previous theoretical models that OST radiation is principally related to the tear film; and demonstrate that it is less related to other characteristics such as corneal thickness, corneal curvature, and anterior chamber depth. © 2007 American Academy of Optometry.

Infrared ocular thermograms were recorded for a group of 36 dry eye patients and for 27 age- and sex-matched controls. Mean ocular surface temperature was greater in the dry eye group (32.38 +/- 0.69 degrees C) compared with the control group (31.94 +/- 0.54 degrees C; p < 0.01). In addition, there was a greater variation of temperatures across the ocular surface in the dry eye group, illustrated by the difference in temperature between the limbus and the centre of the cornea (0.64 +/- 0.20 degrees C in dry eye patients compared with 0.41 +/- 0.20 degrees C in the control group; p < 0.001). This parameter was also shown to be greater in dry eye patients who displayed either a fast tear break-up time or a poor Schirmer's test result. Infrared thermography is a non-invasive and objective technique that may prove a useful research tool for study of the tear film, its deficiencies and its various treatment modalities.

PURPOSE: Corneal temperature changes in photorefractive keratectomy (PRK) have been implicated in the aetiology of subepithelial haze. This study was undertaken to quantify the temperature change during this surgical procedure. METHODS: Non-contact, colour-coded ocular thermography was performed by using an infrared detection system during PRK on a group of 12 subjects. RESULTS: Mean (+/-SD) central ocular surface temperature (OST) after epithelial debridement was 29.15 +/- 0.39 degrees C. Mean peak OST during PRK was 37.77 +/- 0.67 degrees C, with most of the temperature increase occurring during the first 15 s. Factors such as ablation depth, optical correction, and procedure duration were not demonstrated to have a significant effect on corneal temperature during the procedure, suggesting a complex relation between-PRK parameters and the change in corneal temperature. CONCLUSIONS: Previous work suggested that corneal collagen denatures at approximately 39 degrees C, and it has been demonstrated that corneal temperature may be elevated to this level during routine PRK. Further research is indicated into the effects of preoperative cooling and pausing in treatment to reduce temperature changes.

Measuring the surface temperature of the cornea by contact thermometry has the disadvantages that anaesthesia and sterility are necessary and that temperature is measured at a point. A method of measuring corneal temperature using a bolometer that does not have these disadvantages is described, together with the results obtained. In addition the theoretical and practical considerations in its use are discussed. A value for the emissivity of the corneal surface of between 0·97 and 1 is derived.