Thermography: a new option to monitor filtering bleb function?

PURPOSE

To evaluate the filtering bleb function after trabeculectomy using a new ocular surface thermography device.

METHODS

Thirty-five eyes of 35 patients after trabeculectomy were included in this prospective study. The filtering bleb function was tested with a new ocular surface-oriented, infrared radiation thermographic device in a noncontact manner (TG 1000). The eyes were classified into poorly controlled and well-controlled intraocular pressure (IOP) groups according to the patients' postoperative IOP. According to Kawasaki and colleagues, the mean temperature decrease in the filtering bleb (TDB) for evaluating bleb function was used, where TDB=(mean temperature of the temporal and nasal bulbar conjunctiva)-(mean temperature of the filtering bleb). Furthermore, the filtering bleb was evaluated during 10 seconds of eye opening and a new parameter was introduced, the TB10sec. TDB and TB10sec were analyzed statistically.

RESULTS

The TDB was 0.911°C (±0.467) and the TB10sec was -1.027°C (±0.312) in the well-controlled IOP group. The TDB was 0.599°C (±0.499), and the TB10sec was -0.623°C (±0.265) in the poorly controlled IOP group, respectively. The difference in TDB (P=0.045), as well as that of TB10sec (P<0.001), between the well-controlled and poorly controlled IOP groups was significant.

CONCLUSIONS

Temperature decrease in the filtering bleb provides information about its function. Because of the easy handling and reproducible measurements, thermography using Tomey TG 1000 may be a useful tool in the evaluation of filtering bleb function.