title: Long-term trends in intraocular pressure after pars plana vitrectomy.
abstract: OBJECTIVE
  To evaluate the effect of vitrectomy on intraocular pressure (IOP).
  
  
  METHODS
  Retrospective cohort study. Medical records of 101 eyes of 101 patients undergoing nonemergent vitrectomy were reviewed for rates of open-angle glaucoma, increased IOP of >4 mmHg from baseline, change in IOP from baseline, and cataract formation. Preoperative and last measured IOPs were recorded. Baseline risk characteristics including lens status and diabetes were analyzed. Main outcome measures were 1) incidence of open-angle glaucoma; 2) increase in IOP of >4 mmHg; and 3) change in IOP.
  
  
  RESULTS
  Mean follow-up was 49 months (range, 12-105 months). Mean baseline IOP was 15.3 mmHg, and mean final IOP was 15.8 mmHg (P = 0.3). At the most recent examination, 35 study eyes had a decrease in IOP from baseline, while 14 eyes had no change and 52 eyes had an increase in IOP. Four study eyes were newly diagnosed with ocular hypertension. No study eye developed open-angle glaucoma or required medical, laser, or surgical treatment for glaucoma. Incidence of increased IOP of >4 was 7% at 4 years and 34% at 8 years. Subgroup analysis of 66 patients comparing study eyes with nonvitrectomized fellow eyes demonstrated no significant difference in rates of increased IOP of >4 (P = 0.85). Neither diabetes nor pseudophakia was associated with significantly increased IOP.
  
  
  CONCLUSIONS
  In this series, vitrectomy does not appear to increase IOP even after removal of the crystalline lens.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
authors.forename: Maziar
authors.initials: M
authors.lastname: Lalezary
authors.forename: Stephen Jae
authors.initials: SJ
authors.lastname: Kim
authors.forename: Kim
authors.initials: K
authors.lastname: Jiramongkolchai
authors.forename: Franco M
authors.initials: FM
authors.lastname: Recchia
authors.forename: Anita
authors.initials: A
authors.lastname: Agarwal
authors.forename: Paul
authors.initials: P
authors.lastname: Sternberg
mesh_terms: D005260:Female; D005500:Follow-Up Studies; D005902:Glaucoma, Open-Angle / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000453:epidemiology; D011184:Postoperative Period; D012164:Retinal Diseases / Q000601:surgery; D012189:Retrospective Studies; D012307:Risk Factors; D014065:Tonometry, Ocular; D014792:Visual Acuity / Q000502:physiology; D014821:Vitrectomy; D014823:Vitreous Hemorrhage / Q000601:surgery