Prediction of postoperative refractive astigmatism before toric intraocular lens implantation

Abstract

Background To determine the preoperative factors influencing refractive astigmatism after cataract surgery for astigmatism correction by toric intraocular lens (IOL) implantation and to evaluate the prediction model using these factors. Methods Prospective, observational case series. The right eyes of forty consecutive patients with preoperative corneal astigmatism of the total cornea of 1.5 diopters (D) or more in magnitude and scheduled for implantation of a non-toric IOL during cataract surgery with a 2.4-mm temporal clear corneal incision were examined prospectively. The vertical/horizontal astigmatism component (J0) and oblique astigmatism component (J45) of refractive and corneal astigmatism were converted using power vector analysis. Multivariate regression analysis was performed with refractive astigmatism at three months postoperatively as the dependent variable, and preoperative parameters including age, sex, refractive astigmatism, corneal astigmatism, sphere, spherical equivalent, intraocular pressure, corneal thickness, anterior chamber depth, lens thickness, lens positions (tilt and decentration), axial length, and corneal higher order aberrations as independent variables. The root mean square (RMS) errors were calculated to express the regression model fit. Results The regression model for the J0 component was $$ Postoperative\kern0.34em refractive\kern0.2em J0=1.05\times Coneal\kern0.2em J0-0.14 $$ P o s t o p e r a t i v e r e f r a c t i v e J 0 = 1.05 × C o n e a l J 0 − 0.14 (R2 = 0.96, P < 0.001). The model for the J45 component was $$ Postoperative\kern0.34em refractive\kern0.2em J45=0.68\times Coneal\kern0.2em J45+0.19\times Preoperative\kern0.34em refractive\kern0.2em J45-0.06 $$ P o s t o p e r a t i v e r e f r a c t i v e J 45 = 0.68 × C o n e a l J 45 + 0.19 × P r e o p e r a t i v e r e f r a c t i v e J 45 − 0.06 (R2 = 0.72, P < 0.001). The mean RMS errors for preoperative corneal astigmatism alone and the multivariate model were 0.58 D and 0.46 D, respectively. There was a statistically significant difference between them (P = 0.02). Conclusions Refractive astigmatism after implantation of a toric IOL can be predicted by the regression model more accurately than by corneal astigmatism alone. However, the prediction of oblique astigmatism remains a challenge.

Implantation of a toric intraocular lens after repeated radial keratotomy procedures: A case report

“…In addition, the magnitude of total corneal astigmatism (real K) changed from 0.93 D or 1.64 D, preoperatively, to 1.38 D, postoperatively in the right eye, whereas this changed from 3.60 D or 3.81 D, preoperatively, to 4.00 D, postoperatively in the left eye. These changes are comparable to perioperative changes of corneal astigmatism previously reported [ 18 ]. Examining the central 3-mm zone, the corneal regular astigmatism (real K) showed minimal perioperative changes, with values shifting slightly from 0.98 D to 1.08 D in the right eye and from 2.78 D to 2.50 D in the left eye.…”

Comparison of refractive and visual acuity results after Contoura® Vision topography-guided LASIK planned with the Phorcides Analytic Engine to results after wavefront-optimized LASIK in eyes with oblique astigmatism

“…The orientation of astigmatism is also known to be a factor influencing refractive surgery results. Outcomes after cataract surgery and toric IOL implantation tend to be more variable in eyes with oblique astigmatism relative to eyes with ATR or WTR astigmatism [ 12 ]. One study of correcting astigmatism with a corneal refractive procedure suggests results are also more variable when the astigmatism is oblique [ 13 ].…”

Refractive Status in Eyes Implanted with Toric and Nontoric Intraocular Lenses during Combined Cataract Surgery and Microhook Ab Interno Trabeculotomy

“…In two patients of the toric IOL group with high myopia and pseudoexfoliation (PXF), slight deterioration of postoperative absolute refractive astigmatism compared to the preoperative values was observed. Postoperative refractive astigmatism is thought to include toric IOL rotation, lens capsule (and/or IOL) tilt, decentration, and unknown ocular components in addition to corneal astigmatism [ 18 ]. In the high myopic patients with lax capsule and PXF patients with zonular weakness, IOL and capsule tend to rotate and tilt [ 18 , 19 ].…”

“…Postoperative refractive astigmatism is thought to include toric IOL rotation, lens capsule (and/or IOL) tilt, decentration, and unknown ocular components in addition to corneal astigmatism [ 18 ]. In the high myopic patients with lax capsule and PXF patients with zonular weakness, IOL and capsule tend to rotate and tilt [ 18 , 19 ]. In the current study, postoperative toric IOL rotation was not examined, and IOL rotation and/or lens capsule IOL tilt after surgery may have occurred in our two cases; thus, we should take notice of the possibility to not correct the preoperative astigmatism in the patients with high myopia and PXF.…”