title: A novel index for predicting intraocular pressure reduction following cataract surgery.
abstract: OBJECTIVE
  The results of a study designed to investigate the predictive value of preoperative anterior chamber depth (ACD) and intraocular pressure (IOP) are reported. The relation between these factors and their effect on the reduction in IOP following phacoemulsification cataract surgery was also studied.
  
  
  METHODS
  The ACD and IOP were prospectively measured in 103 non-glaucomatous eyes of 103 patients who underwent uneventful phacoemulsification and posterior chamber intraocular lens (PCIOL) implantation. Other data which were recorded included best corrected visual acuity, axial length, lens thickness, and severity of lens opacity.
  
  
  RESULTS
  The ACD increased by a mean (SD) of 1.10 (0.44) mm (p<0.00001) and this increase was significantly and inversely related to preoperative ACD (r(2) = 68%; p<0.01). IOP dropped by a mean of 2.55 (1.78) mm Hg following cataract surgery (p<0.0001), and this reduction was significantly and positively related to preoperative IOP (r(2) = 56%; p<0.01), and significantly and inversely related to preoperative ACD (r(2) = 21%; p<0.01). A novel ratio, the pressure to depth (PD) ratio (preoperative IOP/preoperative ACD), was found to be significantly and positively related to the surgically induced reduction in IOP (r(2) = 73%; p<0.01), and IOP was reduced by > or =4 mm Hg in all patients with a PD ratio >7.
  
  
  CONCLUSIONS
  The reduction in IOP following cataract surgery was found to be positively related to preoperative IOP, and inversely related to preoperative ACD. Furthermore, these results indicate that a novel index, the PD ratio, is strongly predictive for IOP reduction following cataract extraction, and may prove useful in surgical decision making.
authors.affiliation: Department of Ophthalmology, Waterford Regional Hospital, Waterford, Republic of Ireland. sharifissa@yahoo.co.uk
authors.forename: S A
authors.initials: SA
authors.lastname: Issa
authors.forename: J
authors.initials: J
authors.lastname: Pacheco
authors.forename: U
authors.initials: U
authors.lastname: Mahmood
authors.forename: J
authors.initials: J
authors.lastname: Nolan
authors.forename: S
authors.initials: S
authors.lastname: Beatty
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000867:Anterior Chamber / Q000473:pathology; D002386:Cataract / Q000473:pathology / Q000503:physiopathology*; D003657:Decision Making; D006801:Humans; D007429:Intraocular Pressure; D019654:Lens Implantation, Intraocular; D007908:Lens, Crystalline / Q000473:pathology; D008875:Middle Aged; D018918:Phacoemulsification; D011184:Postoperative Period; D011300:Preoperative Care / Q000379:methods; D011379:Prognosis; D011446:Prospective Studies; D014792:Visual Acuity