A four-year prospective study on intraocular pressure in relation to phacoemulsification cataract surgery

Aim of study: To follow up prospectively the intraocular pressure (IOP) of healthy eyes with senile cataract undergoing phacoemulsification surgery over a duration of 4 years. Patients and methods: Thirty-five patients entering first eye cataract surgery had IOP measured by applanation tonometry pre-operatively and on day 1, at 1 month, 6 months, 1 year, 2 years and 4 years after surgery at 9 a. m. and again at 2 p. m. in the Department of Ophthalmology, Oulu University Hospital. Thirty-four patients attended the 1-year checkup, and the 2- and 4-year results are available for 31. Results: The pre-operative IOP was 16.0 (SD 4.3, range 6-25) mmHg in the morning and 16.4 (SD 4.0, range 8-25.5) mmHg in the afternoon. On the first postoperative day, the IOP was 2.1 +/- 5.6 mmHg higher than before surgery (p = 0.029). At 1 month, the IOP morning measurement had decreased 2.8 +/- 3.6 mmHg, and in the afternoon, the decrease was 3.0 +/- 2.7 mmHg from the pre-operative level. At 6 months, the decrease was 3.3 +/- 2.7 mmHg in the morning and 3.6 +/- 2.7 mmHg in the afternoon, at 1 year, 3.2 +/- 3.0 mmHg and 3.5 +/- 3.2 mmHg, at 2 years, 3.2 +/- 2.4 mmHg and 3.1 +/- 2.8 mmHg, and at the 4-year postoperative checkup, 3.6 +/- 3.4 mmHg and 3.6 +/- 2.7 mmHg, respectively (p = 0.000 for all time-points). Conclusions: IOP decreases by about 3 mmHg (16-23% from the pre-operative IOP level) after phacoemulsification and remains at this reduced level with no trend towards an increase during 4 years.