Characterization of the ocular surface temperature dynamics in glaucoma subjects using long-wave infrared thermal imaging

Ocular effects of exposure to low-humidity environment with contact lens wear: A pilot study

PURPOSE

To compare the ocular effects of exposure to a low-humidity environment with and without contact lens (CL) wear using various non-invasive tests.

METHODS

Fourteen habitual soft CL wearers were exposed to controlled low humidity (5% relative humidity [RH]) in an environmental chamber for 90 min on two separate occasions. First, when wearing their habitual spectacles and then, on a separate visit, when wearing silicone hydrogel CLs that were fitted specifically for this purpose. All participants had adapted to the new CL prior to data collection. Three non-invasive objective measurements were taken at each visit: blinking rate, objective ocular scatter (measured using the objective scatter index) and ocular surface cooling rate (measured using a long-wave infrared thermal camera). At each visit, measurements were taken before the exposure in comfortable environmental conditions (RH: 45%), and after exposure to environmental stress (low humidity, RH: 5%).

RESULTS

CL wearers showed increased blinking rate (p < 0.005) and ocular scatter (p = 0.03) but similar cooling rate of the ocular surface (p = 0.08) when compared with spectacle wear in comfortable environmental conditions. The exposure to low humidity increased the blinking rate significantly with both types of corrections (p = 0.01). Interestingly, ocular scatter (p = 0.96) and cooling rate (p = 0.73) were not significantly different before and after exposure to low humidity. There were no significant two-way interactions between correction and exposure in any of the measurements.

CONCLUSIONS

CLs significantly increased the blinking rate, which prevented a quick degradation of the tear film integrity as it was refreshed more regularly. It is hypothesised that the increased blinking rate in CL wearers aids in maintaining ocular scatter quality and cooling rate when exposed to a low-humidity environment. These results highlight the importance of blinking in maintaining tear film stability.

Relative Stability of Regional Facial and Ocular Temperature Measurements in Healthy Individuals

Purpose

Non-contact measurement of facial temperature using infrared thermography has been used for mass screening of body temperature during a pandemic. We investigated the relative stability of temperature measurement in different facial regions of healthy individuals.

Methods

Twenty healthy subjects underwent two experiments. In the first experiment, subjects washed their faces with a 20°C wet towel for 1 minute. Temperature changes compared to baseline in the forehead, cornea, inner canthus, and outer canthus were determined using an infrared camera for 10 minutes. In the second experiment, lubricating eye drops at 20°C were instilled over one eye. Temperature changes in the same regions of interest were monitored for 5 minutes.

Results

Baseline temperatures before face washing in the forehead and cornea, inner canthus, and outer canthus of the right eye were 33.4°C ± 0.8°C (mean ± SD), 33.3°C ± 0.8°C, 34.3°C ± 0.7°C, and 32.8°C ± 0.7°C, respectively. Reductions in temperature due to face washing were most significant for the forehead and least significant for the cornea. One minute after face washing, the corresponding changes were -2.8°C ± 0.6°C, -0.3°C ± 0.6°C, -0.6°C ± 0.7°C, and -0.9°C ± 0.7°C for the forehead, cornea, inner canthus, and outer canthus, respectively. After administering the eye drops, no significant temperature changes were observed.

Conclusions

When facial temperature was exogenously cooled, the cornea had the most stable temperature readings.

Translational Relevance

When using infrared thermography to screen facial temperature, the measurement of corneal temperature is probably a better representative if the stability of temperature readings is critical.

Mucoadhesive brinzolamide-loaded nanofibers for alternative glaucoma treatment

Despite the advances in the field of pharmaceutical materials and technology, topical administration remains a method of choice for the treatment of eye diseases such as glaucoma, with eye drops being a leading dosage form. Their main disadvantage is a very short drug residence time and thus poor drug bioavailability, leading to the necessity of continuous repeated dosing. Mucoadhesive electrospun nanofibers are promising candidates for overcoming these challenges, while still benefiting from topical ocular administration. As an alternative for eye drops, a nanofibrous drug delivery system (DDS) for the delivery of brinzolamide (BRZ), based on β-cyclodextrin (β-CD), hydroxypropyl cellulose (HPC) and polycaprolactone (PCL), was designed. The results showed β-CD/BRZ guest-host interactions, successful drug incorporation into the nanofibers, and the possibility of more accurate dosing in comparison with the control eye drops. Drug permeation through sheep corneas was almost linear in time, achieving therapeutic concentrations in the receptor medium, and mucoadhesion to sheep eye mucosa was relatively high in case of formulations with high HPC content. All formulations were biocompatible, their mechanical properties were sufficient to handle them without caution and UV irradiation was suitable to reduce bioburden of the fibers matrix, yet no antibacterial properties of BRZ were observed.

Measurement of intraocular temperature in glaucoma: week-day and seasonal fluctuations

PURPOSE

To evaluate long-term intraocular temperature (IOT) variations in eyes with primary open-angle glaucoma (POAG) using an intraocular telemetric sensor.

METHODS

This prospective, open-label, multicentre observational study analysed the IOT variations in 22 eyes of 22 patients with POAG. All enrolled patients underwent implantation of an intraocular pressure (IOP) sensor during cataract surgery. The telemetric system uses a built-in temperature sensor to control measured IOP for temperature. Each time a patient measures their IOP, both the IOP and IOT are recorded in the reader device. Patients were instructed to self-measure their IOP as often as desired, but at least four times daily. Recorded readings were retrieved and analysed using mixed effect models and pairwise comparisons using Bonferroni correction to assess the statistical significance of average IOT variations between each individual weekday and calendar month.

RESULTS

The mean age of patients was 67.8±6.8 years and 36.4% were women. A total of 132 745 readings over 21 102 measurement-days were obtained. On average, IOT was significantly higher on Sundays (34.57°C; 95% CI 34.37 to 34.78) than on any other day of the week (p<0.001). Mean IOT on other weekdays ranged from 34.48°C to 34.51°C. Over the year, IOT followed a clear seasonal pattern, reaching its maximum in July (34.8°C; 95% CI 34.56 to 34.97) and its minimum in January (34.4°C; 95% CI 34.15 to 34.56; p<0.001).

CONCLUSIONS

This study demonstrates the feasibility of continual and long-term measurement of IOT using intraocular sensors. The results show significant short-term and long-term fluctuations of IOT. Research is warranted to understand the impact of IOT variations on IOP, ocular perfusion and glaucoma progression.

Ocular surface temperature differences in glaucoma

PURPOSE

Accumulating evidence suggests that neuroinflammation and immune response are part of the sequence of pathological events leading to optic nerve damage in glaucoma. Changes in tissue temperature due to inflammation can be measured by thermographic imaging. We investigated the ocular surface temperature (OST) profile of glaucomatous eyes to better understand the pathophysiology of these conditions.

METHODS

Subjects diagnosed with glaucoma (primary open angle glaucoma [POAG] or pseudo exfoliation glaucoma [PXFG]) treated at the Sam Rothberg Glaucoma Center (11/2019-11/2020.) were recruited. Healthy subjects with no ocular disease served as controls. The Therm-App thermal imaging camera was used for OST acquisition. Room and body temperatures were recorded, and the mean temperatures of the medial cantus, lateral cantus, and cornea were calculated with image processing software.

RESULTS

Thermographic images were obtained from 52 subjects (52 eyes: 25 POAG and 27 PXFG) and 66 controls (66 eyes). Eyes with glaucoma had a significantly higher OST compared to controls (mean 0.9 ± 0.3°C, p < 0.005). The difference between the two groups remained significant after adjustment for age, sex, intraocular pressure (IOP) and room and body temperatures. Lens status and topical IOP-lowering medication did not significantly affect OST. A subgroup analysis revealed that the OST was higher among eyes with POAG compared to eyes with PXFG, but not significantly.

CONCLUSIONS

Differences in the OST between glaucomatous and normal eyes strengthens current thinking that inflammation affects the pathophysiology of glaucoma. Longitudinal studies are warranted to establish the prognostic value of thermographic evaluations in these patients.

[Thermography of ocular surface tissues in the assessment of aseptic postoperative inflammation]

PURPOSE

To determine the thermographic parameters of ocular surface tissues in various types of anti-glaucoma operations.

MATERIAL AND METHODS

The study included 70 patients with glaucoma (140 eyes) and 28 patients (56 eyes) with cataract and planned phacoemulsification. All patients underwent dynamic infrared thermography of the eye surface to evaluate the aseptic inflammatory response before and after surgery.

RESULTS

The increase in the temperature of the ocular surface tissues was longer after penetrating glaucoma surgery than after the non-penetrating type, which indicates a more prolonged inflammatory aseptic reaction in response to surgical intervention.

CONCLUSION

The obtained results allow the development of a rational tactic of preoperative drug preparation and more effective postoperative management.

Design of the ocular coil, a new device for non-invasive drug delivery

Eye drops and ointments are the most prescribed methods for ocular drug delivery. However, due to low drug bioavailability, rapid drug elimination, and low patient compliance there is a need for improved ophthalmic drug delivery systems. This study provides insights into the design of a new drug delivery device that consists of an ocular coil filled with ketorolac loaded PMMA microspheres. Nine different ocular coils were created, ranging in wire diameter and coiled outer diameter. Based on its microsphere holding capacity and flexibility, one type of ocular coil was selected and used for further experiments. No escape of microspheres was observed after bending the ocular coil at curvature which reflect the in vivo situation in human upon positioning in the lower conjunctival sac. Shape behavior and tissue contact were investigated by computed tomography imaging after inserting the ocular coil in the lower conjunctival fornix of a human cadaver. Thanks to its high flexibility, the ocular coil bends along the circumference of the eye. Because of its location deep in the fornix, it appears unlikely that in vivo, the ocular coil will interfere with eye movements. In vitro drug release experiments demonstrate the potential of the ocular coil as sustained drug delivery device for the eye. We developed PMMA microspheres with a 26.5 ± 0.3 wt% ketorolac encapsulation efficiency. After 28 days, 69.9% ± 5.6% of the loaded ketorolac was released from the ocular coil when tested in an in vitro lacrimal system. In the first three days high released dose (48.7% ± 5.4%) was observed, followed by a more gradually release of ketorolac. Hence, the ocular coil seems a promising carrier for ophthalmic drugs delivery in the early postoperative time period.

Characterization of the ocular surface temperature dynamics in glaucoma subjects using long-wave infrared thermal imaging: publisher's note

This publisher's note corrects the funding section in J. Opt. Soc. Am. A36, 1015 (2019)JOAOD61084-752910.1364/JOSAA.36.001015.