Purpose
Previous work has established the Intraocular Pressure (IOP) lowering effect of cataract surgery and has suggested that this IOP lowering effect is due to the effect of ultrasound energy inducing stress on the trabecular meshwork. We further hypothesize that intraoperative factors such as phaco time and percent phaco may have an effect on IOP lowering after cataract surgery. The purpose of this study is to evaluate the effect of demographic, clinical, and specifically intraoperative variables on IOP lowering after cataract extraction.
Methods
We conducted a retrospective chart review of all 157 patients that met our inclusion criteria that underwent cataract surgery at the Baltimore VA hospital for a 2 year period starting January of 2006. Patients who had cataract surgery combined with another ocular procedure, had previous ocular surgery, or had surgical complications were excluded. We included only one eye for patients who had both eyes operated on in the study period. IOP was measured pre-operatively, at 3 months, 6 months, and yearly for 5 years. Pre-operative IOP was an average of the previous 3 IOP measurements. The primary outcome measure was reduction of IO of 20% or greater at 1 and 2 years. SPSS was used for statistical analysis.
Results
Average patient age was 70.8 +/- 11.2 and average follow up was 2.7 years. Pre-operative IOP was noted to be 14.98 +/- 2.90. Average decrease in IOP was noted to be -1.6 +/-3.5 at 3 months, -1.2 +/-3.4 at 6 months, -0.5+/- 3.4 at one year, and -0.4 +/-3.6 at 2 years. Average Phaco time was 18.4 +/- 21.0 and average percent phaco was 10.5 +/- 6.6. On univariate analysis, more myopic pre-operative refractive error was noted to be associated with greater than 20% IOP lowering at one year (-2.43, P = 0.02 95% CI -3.3, -0.3). At two years, higher pre-operative IOP was noted to be associated with greater than 20% IOP lowering (17.1, P<0.01, 95% CI 1.2, 4.3). Percent phaco and phaco time was not associated with greater than 20% IOP lowering at one (P = 0.72, P = 0.56) or two years (P = 0.06, 0.25).
Conclusions
We noted considerable variation in phaco time, percent phaco, and IOP lowering after cataract surgery. Phaco time and percent phaco are not associated with long term decrease in IOP.
Keywords: 445 cataract •
568 intraocular pressure •
462 clinical (human) or epidemiologic studies: outcomes/complications