Abstract
PurposeTo examine the long-term changes in the astigmatism-correcting effect of a toric intraocular lens (IOL) after stabilization of surgically induced astigmatic changes due to cataract surgery.MethodsUnilateral eyes of 120 patients that received a toric IOL for against-the-rule (ATR) or with-the-rule (WTR) astigmatism were enrolled. Manifest refractive and anterior corneal astigmatism, and ocular residual astigmatism which is mainly derived from internal optics were examined preoperatively, at approximately 2 months postoperatively (baseline) and at 5 ~ 10 years postbaseline. The astigmatism was decomposed to vertical/horizontal (Rx) and oblique components (Ry), which was compared between baseline and 5 ~ 10 years postbaseline.ResultsIn the eyes having ATR astigmatism, the mean Rx and Ry of the manifest refractive and corneal astigmatism significantly changed toward ATR astigmatism between the baseline and 5 ~ 10 years postbaseline (p ≤ 0.0304), but those of ocular residual astigmatism did not change significantly between the 2 time points. In the eyes having WTR astigmatism, the Rx and Ry of refractive, corneal, and ocular residual astigmatism did not change significantly between the 2 time points. Double-angle plots revealed an ATR shift in refractive and corneal astigmatism and no marked change in the ocular residual astigmatism in the eyes with ATR astigmatism, and there is no change in this astigmatism in the eyes with WTR astigmatism.ConclusionThe long-term changes with age in the effect of a toric IOL significantly deteriorated due to an ATR shift of corneal astigmatism in the eyes having ATR astigmatism, while it was maintained in eyes having WTR astigmatism, suggesting that ATR astigmatism should be overcorrected.
Highlights
Toric intraocular lenses (IOLs) effectively correct preexisting corneal astigmatism when implanted during cataract surgery and substantially improve uncorrected visual acuity [1,2,3,4,5]
The ocular residual astigmatism, which mainly consists of the effect of a toric IOL, and uncorrected and corrected distance visual acuity did not change significantly for 5 ~ 10 years postoperatively
The present study revealed that, in the eyes having ATR astigmatism before implantation of a toric IOL, the amount of ATR astigmatism of the manifest refractive astigmatism increased significantly in association with an ATR shift of corneal astigmatism over a period of 5 ~ 10 years after stabilization of the astigmatic correcting effect of a toric IOL
Summary
Toric intraocular lenses (IOLs) effectively correct preexisting corneal astigmatism when implanted during cataract surgery and substantially improve uncorrected visual acuity [1,2,3,4,5]. The long-term changes in the visual effects of toric IOLs on astigmatic correction remain unclear. Some studies report that the visual effects and rotational stability of toric IOLs are well maintained over 1- or 2-year follow-up times [14,15,16,17,18]. The long-term changes in the effects of toric IOLs for astigmatism correction after stabilization of surgically induced astigmatic change, have not been evaluated for longer postoperative intervals. The present study examined the changes with age in the astigmatism-correcting effects of toric IOLs for 5 ~ 10 years after stabilization of surgically induced astigmatic changes. In the present study, the long-term changes in the effects of a toric IOL were separately evaluated in eyes having preoperative ATR or WTR astigmatism
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