Anterior, posterior, and nonkeratometric contributions to refractive astigmatism in pseudophakes

Kansara, Neal; Cui, David; Banerjee, Kalins; Landis, Zachary; Pantanelli, Seth

doi:10.1097/j.jcrs.0000000000000390

Cited by 6 publications

(7 citation statements)

References 21 publications

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“… 37–39 Several studies have since used rotating Scheimpflug imaging and dual Scheimpflug and Placido disk imaging to demonstrated that PCA has an average magnitude of approximately 0.24–0.42 D and is vertically oriented in the majority of eyes, particularly in patients with WTR anterior corneal astigmatism. 7 , 9 , 12 , 20 , 22 , 26 , 39–43 LaHood et al 14 measured PCA using the recently released IOLM with SS-OCT and telecentric keratometry and found that PCA ranged from 0 to 1.21 D with an average magnitude of 0.24 D. Similar to Scheimpflug and Purkinje imaging, IOLM measured a vertically oriented steep axis of the posterior cornea in 73% of eyes and PCA was found to be significantly greater in WTR eyes compared to ATR eyes. 14 In the present study, an average PCA of 0.24 ± 0.15 D (ranging from 0 to 0.67 D) was measured using IOLM for all eyes and higher PCA was observed in WTR eyes compared to ATR eyes, which aligns with previous studies.…”

Section: Discussionmentioning

confidence: 99%

Comparison of Barrett Toric Calculations Using Measured and Predicted Posterior Corneal Astigmatism in Cataract Surgery Patients

Lukewich¹,

Murtaza²,

Somani³

et al. 2022

OPTH

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Aim To compare residual astigmatism prediction errors across Barrett toric calculations using predicted posterior corneal astigmatism (PCA) and PCA measured using the IOL Master 700 with total keratometry (IOLM). Methods A retrospective cohort study was undertaken on patients with corneal astigmatism and no other ocular comorbidities that underwent uneventful refractive femtosecond laser-assisted cataract surgery with toric IOL implantation between May 2019 and November 2019. Toric calculations were performed using the Barrett toric calculator and the following values: predicted PCA with anterior corneal measurements from Pentacam, IOLM standard keratometry (SK), OPD scan, and median measurements from these devices; predicted PCA with IOLM total keratometry (TK); and measured PCA with IOLM SK or IOLM TK. Residual astigmatism prediction error was calculated for each device and method of calculation at postoperative month 1 and 3 using the astigmatism double angle plot tool. Results A total of 24 eyes, 10 with-the-rule (WTR), 10 against-the-rule (ATR) and 4 oblique astigmatism, from 24 patients were included in this study. PCA ranged from 0.00 to 0.67 D with a mean of 0.24 ± 0.15 D in all eyes. PCA was significantly greater in WTR eyes (0.32 D) compared to ATR eyes (0.16 D; p < 0.05). In ATR eyes, calculations made using IOLM SK and measured PCA had significantly lower total corneal astigmatism and toric IOL cylinder power compared to calculations made using Pentacam and IOLM TK (p < 0.05). No significant difference in mean absolute or centroid residual astigmatism prediction error was observed across devices or calculation methods. The percentage of eyes with absolute astigmatism prediction errors ≤0.5 D was not significantly different across groups. Conclusion Barrett toric calculations using predicted PCA and PCA measured using IOLM produced comparable residual astigmatism prediction errors. The incorporation of median measurements did not significantly impact calculation accuracy.

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Section: Discussionmentioning

confidence: 99%

Comparison of Barrett Toric Calculations Using Measured and Predicted Posterior Corneal Astigmatism in Cataract Surgery Patients

Lukewich¹,

Murtaza²,

Somani³

et al. 2022

OPTH

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“…All these variables typically have little influence on the total refractive astigmatism in pseudophakia, but they may become relevant when the corneal contribution is very low [ 21 – 23 ]. Moreover, the total amount of the pseudophakic refractive astigmatism cannot be explained by the sole refractive assessment of the anterior segment, even if it is conducted in detail [ 24 ].…”

Section: Discussionmentioning

confidence: 99%

One-dioptre toric IOL versus spherical IOL in eyes with low preoperative corneal astigmatism

Bellucci

Panico²,

Tedesco

et al. 2022

Int Ophthalmol

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Purpose To investigate the advantages/disadvantages of a 1.0 D toric IOL vs spherical IOL after regular phacoemulsification in eyes with preoperative astigmatism ≤ 1 D. Methods Retrospective comparative series involving pseudophakic eyes with preoperative topographic astigmatism ≤ 1.0 D implanted either with monofocal 1.0 D Toric IOL (T-group), or with spherical IOL (S-group). The postoperative refractive astigmatism (PRA, i.e. surgically induced + corneal) was the main outcome; also considered in the analyses were the uncorrected and best-corrected distance visual acuity (VA). The data were referred to the last postoperative follow-up visit, 2 to 4 months after surgery. Results A total of 60 eyes were included: 30 in the T-group and 30 in the S-group, matched for patient’s age, laterality, and axial length. Before surgery, the mean corneal astigmatism was 0.62 ± 0.39 D in the T-group and 0.54 ± 0.33 D in the S-group (p = 0.4). In the S-group, PRA was 0.73 ± 0.37 D, higher than the corresponding preoperative corneal astigmatism (p = 0.040). In the T-group, PRA was 0.58 ± 0.31 D; the variation was not statistically significant. Uncorrected VA was significantly better in the T-group vs the S-group (p = 0.007), and the best-corrected VA was comparable in the two groups. Conclusion The present study indicated that in eyes with very low preoperative astigmatism, 1.0 D toric IOLs were able to limit the increase of the PRA instead of those observed with the spherical IOLs. This could support the better uncorrected VA recorded in the T-group.

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“…The magnitude and meridian of the anterior corneal astigmatism were also measured using TONOREF I and II. Furthermore, ocular residual astigmatism which was defined as the difference between manifest refractive astigmatism and anterior corneal astigmatism by Alpins was calculated [ 24 , 25 ]. …”

Section: Methodsmentioning

confidence: 99%

Long-term changes in the refractive effect of a toric intraocular lens on astigmatism correction

Hayashi

Yoshida

Hayashi

et al. 2021

Graefes Arch Clin Exp Ophthalmol

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Purpose To 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. Methods Unilateral 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. Results In 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. Conclusion The 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.

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Anterior, posterior, and nonkeratometric contributions to refractive astigmatism in pseudophakes

Cited by 6 publications

References 21 publications

Comparison of Barrett Toric Calculations Using Measured and Predicted Posterior Corneal Astigmatism in Cataract Surgery Patients

Comparison of Barrett Toric Calculations Using Measured and Predicted Posterior Corneal Astigmatism in Cataract Surgery Patients

One-dioptre toric IOL versus spherical IOL in eyes with low preoperative corneal astigmatism

Long-term changes in the refractive effect of a toric intraocular lens on astigmatism correction

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