Thermal conduction in posterior scleritis and choroiditis.

Abstract

Purpose : To study transmission of thermal energy in posterior scleritis and choroiditis in an experimental model and in practice.

Methods : Model cadaveric eyes for posterior scleritis and choroiditis were created by eviscerating intraocular contents leaving behind scleral strip attached to sclero-corneal button (SCB) and by peeling sclera leaving behind choroidal tissue attached to SCB respectively. (Figure 1) Scleral and choroidal tissue was immersed in hot water and temperature changes on the SCB were noted using a non-contact thermal camera (FLIR Cat S 60 mobile phone). Using same device thermography was done for at least 4 visits between the active and resolved disease for posterior scleritis, VKH disease and control. Difference between the Central Corneal Temperature (CCT) and the ipsilateral temporal eye brow temperature was studied during the follow up and the maximum (Δt Max) and the minimum difference (Δt Min) was calculated. The difference between Δt Max and Δt Min called amplitude of fluctuation (Δt amp). (Figure 2) Comparison of means for all groups was done using the ANOVA test and a p value of <0.05 was considered significant.

Results : In model choroiditis and scleritis eye temperature changed by 3.23°C and 3.52°C respectively at 5 min. Nine eyes of 9 patients of posterior scleritis and VKH disease and 10 eye of 10 controls were studied. Mean highest CCT in scleritis, VKH and the control was 33.2°C (range: 31.5°C – 34.4°C), 33.8°C (range: 32.2°C -35.1°C), and 33.8°C (range: 32.7°C - 35.3°C) respectively. (p: 0.416) Mean Δt Max in scleritis, VKH and control was 2.3 (range: 1.7-3.7), 1.9 (range: 0.4-2.8) and 2.2 (range: 0.8-3.8) respectively. (p: 0.669) Mean Δt Min in scleritis, VKH and control was 0.4 (range: -1.1- 1.1), 0.6 (range: 0-1.4), and 0.1 (range: -0.2 – 2.8) respectively. (p= 0.249) Mean Δt amp in scleritis, VKH and control was 1.8 (range: 0.8-3.2), 1.3 (range: 0.3-1.9) and 1.2 (range: 0.5-1.8) respectively. (p= 0.082).

Conclusions : In model eyes scleral tissue conducted more thermal energy. No significant difference was noted in Δt amp of scleritis, VKH and control eyes. The significance level increased for the parameter ”Δt amp” compared to “Δt Max” or “Δt Min.”

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Choroiditis and posterior scleritis model. Sclero-corneal button with attached scleral and choroidal tissue immersed in hot water.

 

Thermography in posterior scleritis. Δt Max: 32.9 – 30= 2.9°C (2a). Δt Min: 31.5-29.7= 1.8°C (2b). Δt amp is 2.9 – 1.8= 1.1°C.