Relationship Between Biometric Parameter and IOP Changes Following Cataract Surgery

Abstract

Purpose : Cataract surgery can cause anatomical changes in the eye that may explain intraocular pressure differences over time. We were interested in whether changes in anterior segment parameters 1 month after cataract surgery were associated with a change in intraocular pressure (IOP) on postoperative day 1.

Methods : We used an optical biometer (The Lenstar LS 900, Haag-Streit, Switzerland) to measure Axial length (AL), Central Corneal Thickness (CCT), Aqueous Depth (AD), Anterior Chamber Depth (ACD), Lens Thickness (LT), Power of the Flat Meridian (K1), Power of the Steep Meridian (K2), Astigmatism (AST), White-to-White Distance (WTW), X-Coordinate of Iris Barycenter From Visual Axis (ICX), and Y-Coordinate of Iris Barycenter From Visual Axis (ICY) prior to and approximately one month after uncomplicated cataract surgery. We measured IOP using applanation tonometry (Goldmann or Tonopen) on 3 different days prior to surgery to find the mean preoperative IOP. We defined postoperative IOP on day 1 as IOP measured within 30 hours following surgery. We used univariable linear regression and single backwards elimination multivariable regression to find associations between biometric parameters and day 1 postoperative IOP changes.

Results : We included 26 eyesin this study. Demographics data and baseline characteristics are shown in Table 1. Table 2 shows changes in biometric parameters along with the univariate and multivariate regression results. AD (average increase of 1.52 mm), ACD (average increase of 1.51 mm), and LT (average decrease of 4.12 mm) were significantly altered following cataract surgery. Both the univariable and multivariable models showed LT and ICY to have an inverse association with postoperative IOP on day 1.

Conclusions : In this study, patients with a greater decrease in lens thickness and greater change in Y-coordinate of the iris barycenter from the visual axis after a cataract surgery were more likely to have a higher day one postoperative IOP. These larger changes in biometric parameters may suggest a higher impact to the conventional outflow pathway. Future studies will examine the relative importance of preoperative biometric measures vs. change in biometric measures for their association with both short-term and longer-term IOP.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

 

Table 2: Parameter changes and relationship to IOP change.
*Units for the coefficient are mmHg per parameter unit, e.g. 0.94 mmHg/mm for AL.