[The early postoperative complications and cost-effectiveness analysis of non-penetrating trabecular surgery in patients with primary open angle glaucoma].

Objective: To compare the early postoperative complications of non-penetrating trabecular surgery (NPTS) and modified trabeculectomy (MT) in patients with primary open angle glaucoma, and to analyze the cost-effectiveness of NPTS to prevent adverse events as well.
Methods: One hundred and forty seven consecutive cases (215 eyes) with primary open angle glaucoma from the glaucoma division, Zhongshan Ophthalmic Center, were involved. One hundred and four eyes underwent NPTS; while 111 eyes underwent MT. Visual acuity, intraocular pressure and complications occurred while staying in the hospital, were recorded. Number of need to treat (NNT) was used to analyze the cost-effective for NPTS.
Results: (1) Visual acuity decrease over 2 lines occurred in 25 eyes (24.0%) in NPTS group and 26 eyes (23.4%) in MT group. The difference of visual changes between these two groups was not statistically significant (P > 0.05). (2) One day after the operation, hypotension [IOP less or equal to 5 mm Hg (1 mm Hg = 0.133 kPa)] occurred in 39 eyes in NPTS group (38.2%), and 10 eyes in MT group (9.2%). The difference was significant (P < 0.01). On the day of discharge, the incidence of hypotension was 27.5% in NPTS group and 17.3% in MT group, respectively. The difference was still significant (P < 0.05). (3) Hyphema was found in 20 eyes (19.2%) in NPTS group and ten eyes (9.0%) in MT group. In either group, a surgical procedure was needed in two eyes to evacuate the blood. (4) Two eyes of grade II degrees and five eyes of grade I degrees shallow chamber were found in NPTS group. Five eyes of grade II degrees and five eyes of grade I shallow chamber were found in MT group. The difference of incidence of shallow chamber between these two groups was not statistically significant (P > 0.05). (5) Other complications: In the NPTS group, trabeculo-descemetic membrane rupture occurred in one eye, pupil dilated to 7 mm observed in six eyes; in the MT group, acute elevated IOP occurred in one eye, peripheral anterior synechia at inner incision occurred in one eye, hypotensive macular edema occurred in one eye. (6) The absolute risk ratio (ARR) of NPTS for adverse event was 3.0%, (NNT = 33.2), it costs additional RMB yen 116, 100 for preventing one adverse event. For serious adverse event, ARR = 1.8% (NNT = 55.5), and it costs additional RMB yen 194, 000 to prevent one serious adverse event.
Conclusions: Although the NPTS may reduce the incidence of serious adverse event in comparing with MT, the cost of NPTS is very high, therefore, it is not an optimal procedure in China. Ophthalmologists in the general hospital should familiar with the MT procedure to save the medical expenses.