Abstract
Purpose: :
To evaluate the relationship between IOP control and bleb morphology after trabeculectomy (TLE) in patients with primary open angle glaucoma.
Methods: :
Patients who underwent fornix based TLE with MMC from Jan. to July 2008 at the Japanese Red Cross Medical Center were enrolled. Bleb and supra cilio-choroidal space (SCCS) images were obtained using anterior segment OCT (Visante OCT) at three visits (first visit; within two weeks, second visit; at one month, third visit; three months after TLE). Bleb images were obtained in 4 scanning directions cut at the center of the bleb. SCCS images were taken at 12, 3, 6 and 9 o’clock. Four different parameters were measured ; (a) length of the transparent cavity including loose reticular tissue, (b) a height of the bleb which was defined as distance between the conjunctiva and surface of the sclera, (c) existence of lake under the scleral flap, (d) height of SCCS. Maximum Values of each parameter were selected from all scanning directions. At the third visit, IOP control was judged as follows, good IOP control; post-op IOP with more than 30% reduction of pre-op IOP and less than 21mmHg, and failed IOP control; less than 30% reduction of pre-op IOP or more than 22 mmHg. Statistical significance was evaluated by significance test for group effects in mixed- effects analysis of variance model(a)(b)(d) and fischer’s exact test(c).
Results: :
Thirty four eyes (IOP before TLE; 29.5±7.7mmHg) of 32 patients were used. The good and failed IOP control groups were composed of 25 eyes (13.0±3.3mmHg) and 9 eyes (24.4±8.1mmHg), respectively, with statistical significance in the parameters (a, P=0.047) and (c, P=0.0009) between the two groups. In the good IOP control group, all six eyes with disappeared bleb had a lake under the scleral flap (c). Although there was no significance in parameter (d) between two groups, the height of SCCS at the first visit tended to be larger in the failed IOP control group. Avascular bleb was not observed in any eyes at the third visit.
Conclusions: :
A bleb cavity seemed to be important for IOP control, but a lake under the scleral flap was also very important, possibly enhancing uveo-scleral outflow routes. Large cilio-choroidal detachment in the early post-op period seemed to be a risk for failed IOP control.
Keywords: imaging/image analysis: clinical