Influence of Ocular Residual Astigmatism and Target-Induced Astigmatism on the Efficacy of the Implantation of a Toric Implantable Collamer Lens With Central Hole for Myopic Astigmatism Correction.

Jing Zhao,Jiao Zhao,Xiaoying Wang,Wen Yang,Yishan Qian,Xingtao Zhou,Ling Sun

doi:10.3389/fmed.2021.737358

Abstract

PurposeTo investigate the effects of ocular residual astigmatism (ORA) and target-induced astigmatism (TIA) on the efficacy of toric implantable collamer lens (TICL) with central hole for myopic astigmatism correction.MethodsRetrospective case series. One hundred and eighteen eyes implanted with a TICL (V4c) from 118 patients were included. Subjective refraction and corneal topography were examined preoperatively, at 1 and 12 months postoperatively. The eyes were divided into the low-ORA ( ≤ 0.5 D) and high-ORA (>0.5 D) groups based on vector analysis, and into the low-TIA (≥0.75D and <2 D) and the high-TIA (≥2 D and ≤ 4 D) groups according to preoperative refractive astigmatism. Correction index (CI) and index of success (IOS) were compared between different groups.ResultsAll surgeries were uneventful, and no complications occurred during follow-up. At 1 and 12 months postoperatively, no significant differences were found in CI or IOS values between the high and low ORA groups, while significantly higher CI and lower IOS were detected in the high-TIA group than in the low-TIA group (P < 0.05). No significant difference was found in CI between 1 and 12 months postoperatively in either group (P > 0.05). However, significantly lower IOS was found at 12 months compared with 1 month postoperatively for each group (P < 0.05).ConclusionsToric implantable collamer lens (TICL) implantation is effective in correcting myopic astigmatism and is more effective in eyes with high TIA, while ORA has a minor effect.

Highlights

Ocular refractive astigmatism (RA) is a combination of corneal astigmatism (CA) and ocular residual astigmatism (ORA), CA representing the major component [1]
Laser treatment has a variety of surgical methods, such as laser-assisted in situ keratomileusis (LASIK), laser-assisted subepithelial keratomileusis (LASEK), photorefractive keratectomy (PRK), and small incision lenticule extraction (SMILE)
No significant differences were found in age, sex, sphere, RA, spherical equivalence (SE), corrected distance visual acuity (CDVA), CA, target-induced astigmatism (TIA), intraocular pressure (IOP), and endothelium cell density (ECD) between the high- and lowORA groups

Summary

Introduction

Ocular refractive astigmatism (RA) is a combination of corneal astigmatism (CA) and ocular residual astigmatism (ORA), CA representing the major component [1]. ORA can affect ocular astigmatism in different ways: it can partly neutralize CA, reducing ocular RA, or be superimposed with CA to aggravate RA [2]. Astigmatism can be corrected by refractive surgery including corneal laser treatment and intraocular lens implantation. For eyes in which ORA is the main RA component, laser ablation might induce new astigmatism on the cornea, which is supposed to increase anterior corneal astigmatism to compensate for internal astigmatism. Our team [4–6] has demonstrated that ORA influences the efficacy of LASIK, LASEK, and SMILE in correcting myopic astigmatism when refractive correction is confined to the anterior cornea. Roszkowska [7] evaluated the efficacy, safety, stability, and predictability of PRK in correcting myopic astigmatism, hyperopic astigmatism, and mixed astigmatism, and demonstrated that PRK achieved satisfactory correction of all types of astigmatism with moderate and high cylinder magnitudes after 3 years of follow-up

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Results

Conclusion