Achieved and Functional Optical Zone in Myopic Eyes With High Astigmatism After Small Incision Lenticule Extraction

Liu, Shengtao; Gu, Xuejun; Zhang, Xiaoxue; Zhao, Jing; Zhou, Xingtao

doi:10.3928/1081597x-20220201-01

Cited by 7 publications

(5 citation statements)

References 21 publications

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“…We showed that although SMILE obtained a circular optical zone in the treatment of myopia and astigmatism, astigmatism specifically achieved an elliptical functional optical zone (FOZ). Liu et al ( 48 ) validated in their investigation that eyes with significant astigmatism achieved a higher FOZ and lesser SA induction following SMILE compared to eyes without astigmatism. Therefore, they believe that increasing the size of FOZ can lessen the influence of eccentricity on HOA induction.…”

Section: Discussionmentioning

confidence: 97%

Differences in ocular high order aberrations before and after small incision lenticule extraction for correction of myopia: a systematic review and meta-analysis

Du,

Di,

Yang

et al. 2024

Front. Med.

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ObjectiveTo examine the causes and factors that lead to high order aberration (HOA) during the treatment of myopia using small incision lenticule extraction (SMILE), as well as the differences between SMILE and other corneal refractive surgeries through a systematic review and meta-analysis.MethodsA systematic search was conducted from January 2015 to February 2023 in Pubmed, Embase, Web of Science, and Google Scholar databases to gather relevant studies on SMILE and HOA. Studies meeting specific criteria were chosen, and clinical data was retrieved for analysis.ResultsThis meta-analysis resulted in the inclusion of 19 studies involving 1,503 eyes. Pooled results showed significant induction of total HOA (tHOA, d = −0.21, p < 0.001), spherical aberration (SA, d = −0.11, p < 0.001) and coma aberration (CA, d = −0.18, p < 0.001) after SMILE compared to pre-SMILE, while no significant change in trefoil aberration (TA) was observed (d = −0.00, p = 0.91). There was a significantly lower induction of tHOA after SMILE compared to femtosecond laser-assisted in situ keratomileusis (FS-LASIK, d = 0.04, p < 0.001), and no significant difference was observed compared to wavefront aberration-guided (WFG) refractive surgery (d = 0.00, p = 0.75). There was also a significant association between different levels of myopia and astigmatism, duration of follow-up, lenticule thickness, and preoperative central corneal thickness (CCT) on the induction of tHOA after SMILE (p < 0.05), while the higher preoperative myopia group (sphere > -5D), lower preoperative astigmatism group (cylinder ≤ -1D), larger lenticule thickness group (lenticule thickness > 100 μm), shorter follow-up group (follow-up 1 month postoperatively) and the thicker CCT group (CCT > 550 μm) brought a significant induction of tHOA compared to the opposite comparison group (p < 0.001).ConclusionWhile SMILE can induce HOA significantly, it induces less HOA than FS-LASIK. Postoperative HOA following SMILE can be affected by factors such as myopia, astigmatism, lenticule thickness, CCT, and duration of follow-up. Future research should continue to explore techniques to decrease the induction of HOA by using this methodology.Systematic review registrationhttps://www.crd.york.ac.uk/prospero/.

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Section: Discussionmentioning

confidence: 97%

Differences in ocular high order aberrations before and after small incision lenticule extraction for correction of myopia: a systematic review and meta-analysis

Du,

Di,

Yang

et al. 2024

Front. Med.

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“…Ding et al [ 31 ] confirmed that regardless of the astigmatism intensity, there was no direct relationship between induced aberrations and optical zone eccentricity. Liu et al [ 32 ] found that SA induction in the high astigmatism group was smaller than that in the non-astigmatism group, which they speculated was related to its larger functional optical zone (FOZ). The size of the FOZ may affect the effect of fixation eccentricity on induced CA, as the shape of the FOZ in high astigmatism is elliptical and has a different axis [ 30 ].…”

Section: Discussionmentioning

confidence: 99%

Association of myopia and astigmatism with postoperative ocular high order aberration after small incision lenticule extraction

Du,

Di,

Yang

et al. 2024

BMC Ophthalmol

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Objective To investigate the correlation between higher-order aberrations (HOA) after small incision lenticule extraction (SMILE) and the severity of myopia and astigmatism, along with the relevant factors. These findings will provide valuable insights for decreasing the occurrence of HOA after SMILE and enhancing visual quality. Methods A total of 75 patients (150 eyes) with myopia and astigmatism who underwent SMILE were categorized into four groups based on the severity of myopia and astigmatism: Myopia Group 1 (Group M1, spherical diopter ranged from -1.00 D to -4.00 D), Myopia Group 2 (Group M2, spherical diopter ranged from -4.10 D to -10.00 D), Astigmatism Group 1 (Group A1, cylindrical diopter ranged from 0 D to -1.00 D), and Astigmatism Group 2 (Group A2, cylindrical diopter ranged from -1.10 D to -3.00 D). A comprehensive assessment was performed to examine the association between HOA and various relevant factors, including a detailed analysis of the subgroups. Results Group M1 had significantly lower levels of total eye coma aberration (CA), corneal total HOA (tHOA), internal tHOA, and vertical CA ($${{\text{Z}}}_{3}^{-1}$$ Z 3 - 1 ) after SMILE than Group M2 (P < 0.05). Similarly, Group A1 had significantly lower levels of total eye tHOA, CA, trefoil aberration (TA), corneal tHOA, TA, and vertical TA ($${{\text{Z}}}_{3}^{-3}$$ Z 3 - 3 ) after SMILE than Group A2 (P < 0.05). Pearson correlation analysis indicated a statistically significant positive relationship between the severity of myopia/astigmatism and most HOA (P < 0.05). Subgroup evaluations demonstrated a notable increase in postoperative HOA associated with myopia and astigmatism in Groups M2 and A2 compared with the control group. Lenticule thickness, postoperative central corneal thickness (CCT), postoperative uncorrected distance visual acuity (UDVA), and postoperative corneal Km and Cyl were strongly correlated with most HOA. Age, eyes, and postoperative intraocular pressure (IOP) were only associated with specific HOA. Conclusion HOA positively correlated with the severity of myopia and astigmatism after SMILE. However, this relationship was not linear. HOA after SMILE was influenced by various factors, and additional specialized investigations are required to establish its clinical importance.

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“…It is worth noting that change in the local curvature does not completely reflect the scanning area. For example, Liu et al [33] found that the scanning area after SMILE-corrected myopia and myopic astigmatism was round, but the EOZ was oval. The disadvantage is that each point with zero tangential curvature difference needs to be manually determined by a mouse, and the diameter (one dimension) is measured instead of the area (two dimensions).…”

Section: Evaluation Of Eozmentioning

confidence: 99%

“…However, current research has found that decentration does not exhibit a one-to-one correspondence with the above abnormal visual performance [21, 26, 27, 46]. This is mainly related to the larger EOZ increasing the tolerance of decentration to aberration [3, 33]. For example, in the study of He et al [39], although the decentration induced by SMILE was larger than that induced by FS-LASIK and it was positively correlated with coma and total HOAs, there was no difference in objective visual quality and subjective visual symptoms between the two groups, which may have been due to the larger EOZ of SMILE.…”

Section: Evaluation Of Eozmentioning

confidence: 99%

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Methods of Corneal Vertex Centration and Evaluation of Effective Optical Zone in Small Incision Lenticule Extraction

Chen

Yan

2023

Ophthalmic Res

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Inappropriate small incision lenticule extraction (SMILE) centration methods can affect the decentration of the effective optical zone (EOZ) after operation, which can subsequently lead to the decline of postoperative visual quality. We aimed to provide an overview of corneal vertex (CV) centration methods and an evaluation of the size and decentration of the EOZ in SMILE. We described the CV centration methods for patients with myopia, myopic astigmatism, hyperopia, and large kappa angle. The measurement methods of the EOZ were evaluated from the aspects of corneal morphology and corneal refractive power. Additionally, we summarized the advantages and disadvantages of measuring decentration based on topographic mapping and intraoperative video-captured images. Finally, we discussed the relationship between the EOZ and visual quality. Based on our review, clinicians should consider the following when choosing CV centration methods and evaluating EOZ postoperatively. First, the tear film mark center or topographic map comparison method is preferred for the correction of myopia, low myopic astigmatism, hyperopia, and large kappa angle (>0.2 mm). Triple marking centration is recommended for high myopic astigmatism (-3.5 diopters). Second, the total corneal power better reflects the change in refractive power than the topographic method. The measurement of the area rather than the diameter of the total corneal refractive power is more suitable for the evaluation of non-circular EOZs after high myopia astigmatism (< -2.0 diopters). Third, for the evaluation of decentration, the tangential curvature difference map method is preferred as it is not influenced by offset pupils. Finally, a large EOZ after SMILE may improve patient tolerance to decentration.

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Achieved and Functional Optical Zone in Myopic Eyes With High Astigmatism After Small Incision Lenticule Extraction

Cited by 7 publications

References 21 publications

Differences in ocular high order aberrations before and after small incision lenticule extraction for correction of myopia: a systematic review and meta-analysis

Differences in ocular high order aberrations before and after small incision lenticule extraction for correction of myopia: a systematic review and meta-analysis

Association of myopia and astigmatism with postoperative ocular high order aberration after small incision lenticule extraction

Methods of Corneal Vertex Centration and Evaluation of Effective Optical Zone in Small Incision Lenticule Extraction

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