Thermography in the assessment of filtering bleb condition

PURPOSE: To assess the state of the filtration bleb in patients with open-angle glaucoma in different terms after glaucoma surgery by method of thermography.

MATERIALS AND METHODS: 35 patients (35 eyes) with open-angle glaucoma were examined 1, 7 days, and 1-3-6 months after minimally invasive sinustrabeculectomy using the infrared camera Тesto 875-2i with SuperResolution technology and telephoto lens 9×7°. The bleb area and temperature were evaluated With IRSoft and Universal Desktop Ruler software. Intraocular pressure (corneal compensated) (IOPcc) was measured with Ocular Response Analyzer® (ORA). Investigation protocol included 2 groups. Group 1 — 15 patients (15 eyes) with moderate glaucoma. Group 2 — 20 patients (20 eyes) with advanced glaucoma. All patients went through glaucoma surgery, microinvasive sinustrabeculectomy. Management and recurrent examinations were carried on the first day and 7 days after glaucoma surgery; then 1, 3 and 6 months after surgery.

RESULTS: The IOP level was significantly lowered in all patients in all terms of management in comparison with the baseline IOP level. High statistical correlation was determined in patients of 1 group between IOPcc and the index of temperature difference between the filtering bleb (Tfb) and surrounding conjunctiva temperatures (Tsc), in all management terms after surgery (in 1, 3, 6 months) with correlation coefficient of >0.7. In group 2 statistical correlation was determined between IOPcc and index of temperature difference between filtering bleb and surrounding conjunctiva temperatures (Δ Тsc – Тfb) at 1 week, 1 and 3 months after surgery. The same correlation coefficient was determined between filtering bleb temperature and Δ Тsc – Тfb at 6 months after surgery.

CONCLUSION: Thermography is a safe and noninvasive method that credibly detects temperature elevation in surgery zone, indicates IOP level raise and can predict the beginning of filtering bleb scarring. This method shows the necessity of needling procedure in different terms after surgical treatment and allows to control its effectiveness.

open-angle glaucoma, filtering bleb, scarring, thermography, corneal compensated intraocular pressure, Ocular Response Analyzer

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