title: A four-year prospective study on intraocular pressure in relation to phacoemulsification cataract surgery.
abstract: OBJECTIVE
  To follow up prospectively the intraocular pressure (IOP) of healthy eyes with senile cataract undergoing phacoemulsification surgery over a duration of 4 years.
  
  
  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.
authors.affiliation: Department of Ophthalmology, Oulu University Hospital, Oulu, Finland. Aura.Falck@ppshp.fi
authors.forename: Aura
authors.initials: A
authors.lastname: Falck
authors.forename: Nina
authors.initials: N
authors.lastname: Hautala
authors.forename: Nina
authors.initials: N
authors.lastname: Turunen
authors.forename: Pentti Juhani
authors.initials: PJ
authors.lastname: Airaksinen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure / Q000502:physiology; D015992:Body Mass Index; D002386:Cataract / Q000209:etiology; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D018918:Phacoemulsification; D011184:Postoperative Period; D011446:Prospective Studies; D013997:Time Factors; D014065:Tonometry, Ocular