Abstract
Purpose :
To compare refractive prediction error (PE)s between phacotrabeculectomy and phacoemulsification.
Methods :
Refractive PE was defined as the difference of spherical equivalent between the predicted value using the Barrett Universal II formula and the actual value obtained at postoperative one month. 48 eyes that had undergone uncomplicated phacotrabeculectomy (19 eyes, open-angle glaucoma; 29 eyes, angle-closure glaucoma) were matched with 48 eyes that had undergone uncomplicated phacoemulsification by age, average keratometry value and axial length (AL), and their PEs were compared. The factors associated with PE were analyzed by multivariable regression analyses.
Results :
The absolute PE was larger in the phacotrabeculectomy group than in the phacoemulsification group (0.51 ± 0.37D vs. 0.38 ± 0.22D, P=0.033). Larger absolute PE was associated with both longer AL (P=0.010) and higher △intraocular pressure (IOP) (P=0.012). A logistic regression analysis showed that hyperopic shift (PE>0) was associated with shallower preoperative anterior chamber depth (ACD) (P=0.024) and larger △IOP (P=0.031). In the phacotrabeculectomy group, the PE was inversely correlated with AL: long eyes showed myopic shift and short eyes hyperopic shift (P=0.002).
Conclusions :
Intraocular lens power calculation might be less accurate in phacotrabeculectomy than in phacoemulsification due to large AL and ACD changes with IOP lowering. Surgeons therefore should be aware of the possibility of worse refractive outcomes when planning phacotrabeculectomy especially in eyes with high preoperative IOP, shallow ACD, and/or extreme AL.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.