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B. K. Windisch, P. E. Rafuse, L. M. Shuba, M. T. Nicolela; Prediction of the Intraocular Pressure After Trabeculectomy or Phaco-Trabeculectomy. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4158. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Trabeculectomy is the most commonly performed glaucoma procedure worldwide. During surgery, physicians usually adjust the tension of the sutures in the scleral flap until the desired amount of fluid efflux is obtained. The main purpose of this study is to prospectively investigate the surgeons' accuracy of prediction of early postoperative intraocular pressure (IOP) based on the fluid drainage observed at the completion of the surgery.
62 glaucoma patients undergoing primary trabeculectomy (T) or phaco-trabeculectomy (PT) with mitomycin C were prospectively and consecutively enrolled in this observational study. Either one of the three glaucoma specialists or one glaucoma fellow performed all surgeries. The surgeon and the surgeon assistant independently predicted at the end of the surgery the IOP on the first postoperative day, based on the intraoperative assessment of the degree of fluid egress observed during surgery.
On the first postoperative day the measured mean IOP was 24.03 (±10.4 mmHg). The surgeons predicted on average IOP’s that were 3.76 mmHg lower than what was observed (P=0.00). The IOP predictions were within 5 mmHg of the observed IOP in 24 (38.7%) patients, between 6 to 11 mmHg in 18 (29.0%) patients, between 12 to 17 mmHg in 13 (21.0%) patients and greater than 18 in 7 (11.3%) patients. IOP predictions were within 5 mm Hg in 51.9% of cases of primary T, but only in 28.6% of primary combined PT (P=0.08). The accuracy of IOP predictions was independent on the surgeon (P=0.69), but some observers were more accurate than others in predicting the IOP (P=0.05).
Surgeons were able to predict the IOP’s on the first postoperative day within 5 mmHg in about 40% of cases, but in 60% of cases predictions were off by more than 5 mmHg. On average, the predicted IOP’s tended to be lower than the measured IOP. There was a trend for more accurate predictions in T than in PT, but the difference did not reach statistical significance. The future goal of this prospective study is to evaluate whether early IOP is a good predictor of long-term IOP control or need for additional procedures such as laser suture lysis or bleb needling.
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