Fluctuation of intraocular pressure in glaucoma patients before and after trabeculectomy with mitomycin C

PURPOSE: Intraocular pressure (IOP) fluctuation is considered as a risk factor for glaucoma progression. We investigated IOP values and IOP fluctuation before and after trabeculectomy (TE) with mitomycin C (MMC) measured by 48-hour diurnal-nocturnal-IOP-profiles (DNP). METHODS: Pre- and postoperative DNPs of 92 eyes undergoing primary TE with MMC were analysed. Each 48-hour IOP-profile involved 10 IOP measurements (8:00 a.m., 2:00 p.m., 6:00 p.m., and 9:00 p.m. in sitting and at 00:00 in supine position). The "preoperative DNP" was performed a few weeks before TE. The "postoperative DNP" was performed at least six months (range: 6 months-2 years) after TE. Mean IOP values and IOP fluctuations were calculated. RESULTS: After TE with MMC mean IOP was reduced from 16.94±3.83 to 11.26±3.77 mmHg at daytime and from 18.17±4.26 to 11.76±3.90 mmHg at night. At daytime mean IOP-fluctuation decreased from 8.61±4.19 to 4.92±2.52 mmHg, at night from 3.15±2.95 to 1.99±1.82 mmHg. Mean IOP was lower on the second day of the preoperative DNP. This effect was not present in the postoperative DNP. Preoperatively, IOP was controlled in all eyes with a mean of 3.22±0.94 antiglaucomatous agents. Postoperatively, IOP≤15 mmHg was achieved in 71.7%, IOP≤18 mmHg in 77.1% and a decrease in IOP of >30% in 47.8% without antiglaucomatous therapy. Postoperatively, pseudophakia was associated by a higher mean IOP-fluctuation compared to the phakic eyes. CONCLUSIONS: TE with MMC significantly reduces both mean IOP-values and IOP- fluctuations at day and night at least 6 months postoperatively. The effect of TE on the IOP fluctuation was less pronounced in pseudophakic eyes.