Intraocular pressure decrease after phacoemulsification in patients with pseudoexfoliation syndrome

Purpose: To determine the intraocular pressure (IOP) response to phacoemulsification cataract extraction with posterior chamber intraocular lens (PC IOL) implantation in patients with pseudoexfoliation syndrome.Setting: Eye clinics at the University of Ottawa Eye Institute, Ottawa, Ontario, Canada.Methods: A retrospective cohort study design assigned patients to 1 of 3 subgroups: pseudoexfoliation syndrome (PEX) (n = 21), primary open-angle glaucoma (POAG) control (n = 23), and cataract control (n = 23). Inclusion criteria consisted of age older than 50 years, open angle by gonioscopy, and a cataract requiring phacoemulsification. The IOP response was determined at intervals up to 18 months.Results: Postoperative IOP changes from baseline in the PEX group were -1.81, -4.52, and -2.31 mm Hg at 3, 6, and 12 months, respectively. The changes in the POAG control group were -2.22, -2.32, and -1.88 mm Hg, respectively, and in the cataract control group, -2.49, +0.45, and +0.28 mm Hg. Patients in the PEX group had a reduction in IOP from baseline at all postoperative measurements. That reduction was significantly greater than in the POAG and cataract control groups at 6 months (P =.012 and P =.002, respectively) and 12 months (P =.001 and P =.050, respectively).Conclusions: Patients with pseudoexfoliation syndrome had a postoperative IOP reduction from baseline at all measurements and a significantly greater reduction than patients in the POAG and cataract control groups at 6 and 12 months. Phacoemulsification cataract surgery with PC IOL implantation may be effective in managing patients with pseudoexfoliation syndrome who have elevated IOP and visually significant cataract but no advanced optic nerve damage

Correction of intraocular pressure for changes in central corneal thickness following photorefractive keratectomy

Objective: To investigate the relation between measurements of intraocular pressure (IOP) and central corneal thickness (CCT) in myopic patients undergoing photorefractive keratectomy (PRK).Design: Descriptive study.Setting: University-affiliated eye care centre in Ottawa.Patients: A total of 481 consecutive eyes of 318 patients with a mean preoperative refractive error of -6.50 dioptres treated with excimer PRK between March 1993 and December 1996.Outcome measures: IOP measured by Goldmann applanation tonometry and CCT before and 3, 6, 12, 18 and 24 months after surgery.Results: CCT was a significant predictor of IOP only before PRK and 6 months after PRK (p \u3c or = 0.05). The relation between IOP and CCT suggests corrections for CCT that are not clinically significant (0.81 mm Hg [standard error (SE) 0.33 mm Hg] and 1.00 mm Hg [SE 0.38 mm Hg] per 100 microns of corneal thinning preoperatively and at 6 months respectively). On average, there was a significant decrease in IOP after PRK (0.96 mm Hg and 1.24 mm Hg at 12 and 24 months respectively) (p \u3c 0.05). There was a significant correlation between change in IOP and change in CCT (decrease of 2.1 mm Hg per 100 microns of corneal thinning) (p \u3c 0.05). For a given change in CCT, individual changes in IOP were variable, with increases or decreases of more than 5 mm Hg in some cases.Conclusions: There are individual differences in IOP changes following PRK. Until further data are available we propose that the change in IOP between the preoperative visit (or the fellow eye, if healthy or untreated) and the 12-month visit be used as an individual correction factor to be applied to IOP measurements in the operated eye

Changes in measured intraocular pressure after hyperopic photorefractive keratectomy

Purpose: To investigate the effect of hyperopic photorefractive keratectomy (PRK) on intraocular pressure (IOP) measurements.Setting: University of Ottawa Eye Institute, Ottawa Hospital, Ottawa, Canada.Methods: In this retrospective cohort study, IOP and central corneal thickness (CCT) were measured preoperatively and at 1, 2, 3, 6, 12, 18, and 24 months in 191 eyes that had hyperopic PRK with the VISX Star excimer laser. All corrections applied were between +1.00 and +6.50 diopters (D) of sphere and less than 3.75 D of cylinder.Results: At all postoperative examinations, the mean IOP in the hyperopic PRK group was 1.0 to 1.8 mm Hg lower than the preoperative IOP (P \u3c.001). A large range of IOP changes was found across the population; eg, at 6 months, 49% of the eyes had a change in IOP from baseline of at least +/-3 mm Hg. A mean reduction of 19 microm of CCT was found with pachymetry after surgery (P \u3c .001). The change in IOP readings postoperatively was not correlated with age, sex, keratometric readings, or applied correction. Changes in IOP were strongly correlated with preoperative IOP at all time points and with preoperative CCT at 18 and 24 months (P \u3c .001). After hyperopic PRK, the measured IOP was more likely to increase in patients with preoperative IOPs less than 14.5 mm Hg and more likely to decrease in patients with preoperative IOPs above 14.5 mm Hg.Conclusion: Changes in IOP after hyperopic PRK were similar to changes after myopic PRK, despite only minimal changes in the CCT. This suggests that hyperopic PRK results in biomechanical effects that modify the elastic properties of the cornea beyond the changes in rigidity expected from central corneal thinning. There was a strong negative correlation between the measured preoperative IOP and the change in IOP postoperatively that was likely the result of regression of the mean effect

Intraocular pressure following phacoemulsification in patients with and without exfoliation syndrome: A 2 year prospective study

Aim: To determine the long term intraocular pressure (IOP) response to phacoemulsification in patients with and without exfoliation syndrome (XFS).Methods: Prospective, multicentre, cohort study with the following inclusion criteria: age over 50 years, open iridocorneal angle, and cataract. Two groups were enrolled: those with XFS and those without. The main outcome was mean IOP reduction 2 years after phacoemulsification cataract extraction (PCE). Univariate and multivariate analyses were performed.Results: 183 patients were enrolled, 71 with and 112 without XFS. There were 29 patients with glaucoma in both groups. Mean baseline IOP was higher in XFS compared to control eyes (17.60 (SD 3.23) mm Hg v 16.08 (3.18) mm Hg, p = 0.002). Overall IOP reduction was significantly greater in the XFS group at the 2 year time point (-1.85 mm Hg v -0.62 mm Hg in the controls (p = 0.0037)). Multivariate analysis demonstrated that the IOP lowering effect in the XFS group may be related to irrigation volume at the time of surgery. In the subgroup analyses IOP lowering was significantly greater in the XFS and XFG patients than in controls without glaucoma, and POAG controls, respectively. The percentage of patients with a postoperative IOP spike was similar and relatively high in both XFS and control groups (34% v 25%; p = 0.54).Conclusion: IOP decreases more in patients with XFS following PCE compared to control eyes without XFS. This effect is more pronounced in glaucoma patients and persists for at least 2 years