Thermography in posterior scleritis

A.&nbsp;Kawali, S.&nbsp;Sanjay, P.&nbsp;Mahendradas, R.&nbsp;Shetty Narayana Nethralaya Eye Hospital, Bangalore, India Aim: to evaluate the utility of thermography in posterior scleritis (PS). Patients and Methods: this prospective observational case-control study included 6 patients with monolateral PS (study group) and 10 healthy volunteers (control group). Ocular surface temperature (OST) was measured in all participants using a non-contact thermal camera (FLIRTM) integrated onto a smartphone (CAT S 60). The difference in OST between the affected eye and the healthy (fellow) eye on thermograms (Δt) was measured at each visit in both groups. Maximum (ΔtMax) and minimum (ΔtMin) Δt for each eye as well as the amplitude of fluctuations (ampΔt) referred to as the difference between ΔtMax and ΔtMin were calculated for each eye. AmpΔt was compared between the groups. Results: in a total of 6 PS patients, B-scan ultrasonography revealed the thickening of the posterior sclera. Choroidal folds (n=4), internal limiting membrane fold (n=2), subretinal fluid (n=3), and optic disc edema (n=2) were identified by eye fundus exam. At presentation, Δt was maximum in all PS patients and reduced unequally after starting treatment. Mean ampΔt was 1.21 °C (1.47–1.04 °C) in PS group and 0.44 °C (0.13–0.63 °C) in the control group. 3 out 6 PS patients were diagnosed with recurrences as demonstrated by OST spikes compared to previous measurements. Conclusion: this article describes a novel technique of the measurement and monitoring of OST. It was demonstrated that PS is associated with the increase in OST measured by thermography. Further large-scale studies are needed to evaluate the potentialities of thermography for detecting occult or subclinical intraocular inflammation. Keywords: ocular thermography, posterior scleritis, ocular surface temperature, eye temperature, occult inflammation. For citation: Kawali A., Sanjay S., Mahendradas P., Shetty R. Thermography in posterior scleritis. Russian Journal of Clinical Ophthalmology. 2020;20(4):204–208. DOI: 10.32364/2311-7729-2020-20-4-204-208. <br

Multimodal Imaging of the Normal Eye

Multimodal imaging is the concept of \ue2\u80\u9cbundling\ue2\u80\u9d images obtained from various imaging modalities, viz., fundus photograph, fundus autofluorescence imaging, infrared (IR) imaging, simultaneous fluorescein and indocyanine angiography, optical coherence tomography (OCT), and, more recently, OCT angiography. Each modality has its pros and cons as well as its limitations. Combination of multiple imaging techniques will overcome their individual weaknesses and give a comprehensive picture. Such approach helps in accurate localization of a lesion and understanding the pathology in posterior segment. It is important to know imaging of normal eye before one starts evaluating pathology. This article describes multimodal imaging modalities in detail and discusses healthy eye features as seen on various imaging modalities mentioned above

Aqueous humor tyrosinase activity is indicative of iris melanocyte toxicity

Antibiotics such as fluoroquinolones (FQLs) are commonly used to treat ocular infections but are also known to cause dermal melanocyte toxicity. The release of dispersed pigments from the iris into the aqueous humor has been considered a possible ocular side effect of the systemic administration of FQLs such as Moxifloxacin, and this condition is known as bilateral acute iris transillumination (BAIT). Bilateral acute depigmentation of iris (BADI) is a similar condition, with iris pigment released into the aqueous, but it has not been reported as a side effect of FQL. Iris pigments are synthesized by the melanogenic enzyme tyrosinase (TYR) and can be detected but not quantified by using slit-lamp biomicroscopy. The correlation between dispersed pigments in the aqueous and the extent of melanocyte toxicity due to topical antibiotics in vivo is not well studied. Here, we aimed to study the effect of topical FQLs on iris tissue, the pigment release in the aqueous humor and the development of clinically evident iris atrophic changes. We evaluated this process by measuring the activity of TYR in the aqueous humor of 82 healthy eyes undergoing cataract surgery following topical application of FQLs such as Moxifloxacin (27 eyes, preservative-free) or Ciprofloxacin (29 eyes, with preservative) or the application of non-FQL Tobramycin (26 eyes, with preservative) as a control. In addition, the patients were questioned and examined for ocular side effects in pre- and post-operative periods. Our data showed a significantly higher mean TYR activity in the aqueous humor of Ciprofloxacin-treated eyes compared to Moxifloxacin- (preservative free, p < 0.0001) or Tobramycin-treated eyes (p < 0.0001), which indicated that few quinolones under certain conditions are toxic to the iris melanocytes. However, the reduced TYR activity in the aqueous of Moxifloxacin-treated eyes was possibly due to the presence of a higher drug concentration, which inhibits TYR activity. Consistently, immunoblotting analysis of the aqueous humor from both Ciprofloxacin- and Moxifloxacin-treated eyes showed the presence of soluble TYR enzyme, thus reflecting its toxicity to iris melanocytes and corresponding to its activity in the aqueous humor. Intriguingly, none of these patients developed any clinically appreciable ocular side effects characteristic of BAIT or BADI. Overall, our results suggest that topical antibiotics cause different levels of iris melanocyte toxicity, releasing dispersed pigments into the aqueous humor, which can be measured through TYR enzyme activity. Hence, we conclude that topical FQLs may cause subclinical toxicity to the iris melanocytes but may not be the sole cause of the development of BAIT or BADI. (C) 2017 The Authors. Published by Elsevier Ltd