Effect of axis orientation on visual performance in astigmatic eyes

Kobashi, Hidenaga; Kamiya, Kazutaka; Shimizu, Kimiya; Kawamorita, Takushi; Uozato, Hiroshi

doi:10.1016/j.jcrs.2012.03.032

Cited by 60 publications

(60 citation statements)

References 26 publications

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“…Oblique axis astigmatism has been associated with poorer visual performance than WTR or ATR astigmatism. 25,26 Our J45 regression slope results are similar to the findings of Tong et al 16 and Huynh et al 21 Relation Between Change in Keratometric Astigmatism and Change in Internal Astigmatism With Age…”

Section: Relation Between J45 Keratometric Astigmatism and J45 Internsupporting

confidence: 89%

Longitudinal Change and Stability of Refractive, Keratometric, and Internal Astigmatism in Childhood

Harvey¹,

Miller²,

Twelker³

et al. 2014

Investigative Ophthalmology & Visual Science

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PURPOSE. To assess longitudinal change in refractive, keratometric, and internal astigmatism in a sample of students from a population with a high prevalence of with-the-rule (WTR) astigmatism and to determine the optical origins of changes in refractive astigmatism. METHODS.A retrospective analysis of longitudinal measurements of right eye refractive and keratometric astigmatism in Tohono O'odham Native American children was conducted. Changes in refractive and keratometric astigmatism per year were compared in a younger cohort (n ¼ 1594, 3 to <11 years old) and an older cohort (n ¼ 648, 11 to <19 years old). Data were analyzed in clinical notation (Cyl) and vector notation (J0, J45). RESULTS.On average, refractive astigmatism (means: 1.19 diopters [D] Cyl, þ0.54 J0, þ0.03 J45) resulted primarily from WTR corneal astigmatism (means: þ0.85 J0, À0.02 J45) and against-the-rule (ATR) internal astigmatism (means: À0.31 J0, þ0.05 J45). Mean longitudinal changes in astigmatism were statistically significant (younger cohort À0.02 D/y Cyl; older cohort þ0.06 D/y Cyl). In the younger cohort, astigmatism decreased with age in low and moderate astigmats (<3.00 D) and increased with age in high astigmats ( ‡3.00 D). In the older cohort, astigmatism increased with age across all levels of astigmatism. Longitudinal changes in keratometric and internal astigmatism were negatively correlated in both cohorts.CONCLUSIONS. Cross-sectional data suggest the presence of a constant ATR contribution from internal astigmatism (0.60 D Cyl) that is close to the 0.50 D ATR constant reported by Javal and others. Highly astigmatic 3-to <11-year-old children and children older than age 11 years show a small (not clinically significant) increase in astigmatism with age. A negative correlation between changes in keratometric astigmatism and internal astigmatism suggests an active compensation that may contribute to the stability of astigmatism in Tohono O'odham children.Keywords: astigmatism, refractive error development, children, Native American R esearch conducted over the past 15 years has yielded a large longitudinal database on refractive development in Tohono O'odham children. There is a high prevalence of astigmatism among elementary school children who are members of this Native American tribe.1-4 The high prevalence of refractive astigmatism in Tohono O'odham children is present in infancy and persists at least through elementary school. 1,2,4-7 A longitudinal study of corneal astigmatism in 960 Tohono O'odham children aged 6 months through 7 years showed that in early development (6 months to <3 years), astigmatism decreased in children with high astigmatism (À0.37 diopters [D]/y) and remained stable in children with little or no astigmatism (þ0.05 D/y).7 From age 3 through 7 years, astigmatism decreased in children with both high astigmatism (À0.11 D/y) and low/no astigmatism (À0.03 D/y). 7 A detailed account of changes in astigmatism beyond age 7 years in this population has not yet been reported. However, a recent report on change...

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Section: Relation Between J45 Keratometric Astigmatism and J45 Internsupporting

confidence: 89%

Longitudinal Change and Stability of Refractive, Keratometric, and Internal Astigmatism in Childhood

Harvey¹,

Miller²,

Twelker³

et al. 2014

Investigative Ophthalmology & Visual Science

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“…In this sense, a number of studies have not found a strong effect of induced cylinder axis on the changes in VA with astigmatism 19, 20, 21, 22, 23, 30. However, other studies have reported that ATR induced a greater reduction in VA compared to with WTR astigmatism6, 8, 24, 25, 26, 27, 28 and vice versa 25 . Methodological differences in terms of how astigmatism was simulated (with a cross-cylinder, pure positive cylindres, etc.)…”

Section: Discussionmentioning

confidence: 96%

“…On the contrary, in the description of a surgical method for optimizing the outcomes of refractive surgery, Alpins 26 also assumed that WTR astigmatism has a greater optical tolerance than ATR or oblique astigmatism. Kobashi et al 27 reported that oblique astigmatism had lower VA and reading performance than those with uncorrected 0° and 90° axis of astigmatism. Atchinson et al 8 found that subjective blur-limits for cylinder at 0° axis, were greater (about 20%) than those for oblique axes.…”

Section: Introductionmentioning

confidence: 99%

Influence of different types of astigmatism on visual acuity

Remón

Monsoriu

Furlan

2017

Journal of Optometry

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PurposeTo investigate the change in visual acuity (VA) produced by different types of astigmatism (on the basis of the refractive power and position of the principal meridians) on normal accommodating eyes.MethodsThe lens induced method was employed to simulate a set of 28 astigmatic blur conditions on different healthy emmetropic eyes. Additionally, 24 values of spherical defocus were also simulated on the same eyes for comparison. VA was measured in each case and the results, expressed in logMAR units, were represented against of the modulus of the dioptric power vector (blur strength).ResultsLogMAR VA varies in a linear fashion with increasing astigmatic blur, being the slope of the line dependent on the accommodative demand in each type of astigmatism. However, in each case, we found no statistically significant differences between the three axes investigated (0°, 45°, 90°). Non-statistically significant differences were found either for the VA achieved with spherical myopic defocus (MD) and mixed astigmatism (MA). VA with simple hyperopic astigmatism (SHA) was higher than with simple myopic astigmatism (SMA), however, in this case non conclusive results were obtained in terms of statistical significance. The VA achieved with imposed compound hyperopic astigmatism (CHA) was highly influenced by the eye's accommodative response.ConclusionsVA is correlated with the blur strength in a different way for each type of astigmatism, depending on the accommodative demand. VA is better when one of the focal lines lie on the retina irrespective of the axis orientation; accommodation favors this situation.

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“…The current cases with WTR astigmatism in the non-toric group had less residual refractive cylinder compared to the cases with ATR astigmatism. Some studies have reported less of an effect on VA in cases with WTR astigmatism [14,15]. A recent study of posterior astigmatism reported the amount of overestimated cylinder when the anterior astigmatism is measured in cases with WTR astigmatism and underestimated in cases with ATR astigmatism, and a new nomogram was recommended [16,17].…”

Section: Discussionmentioning

confidence: 99%

Comparison between Toric and Non-Toric Intraocular Lenses in Patients with Corneal Astigmatism: A One-Year Multicenter Study

Miyajima¹,

Inoue²

2016

J Clin Exp Ophthalmol

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Objective: To compare the clinical results obtained with a toric intraocular lens (IOL) and non-toric IOL in eyes with corneal astigmatism.Methods: This multicenter retrospective study included eyes with corneal astigmatism ranging from 0.75 diopter (D) to 3.00 D that were implanted with a toric IOL and a non-toric IOL. Non-toric IOLs were implanted before toric IOLs were approved, and the eyes were divided into three groups (T3, T4, or T5) depending on the preoperative degree of corneal astigmatism. Residual refractive cylinder, uncorrected distance visual acuity (UDVA), and contrast sensitivity were compared more than 1 year after implantation. Results:The toric group included 149 eyes (mean patient age, 73.7 ± 7.9 years standard deviation, SD) and the non-toric group included 121 eyes (mean patient age, 76.2 ± 5.9 years). One year postoperatively, the respective residual refractive cylinder values and ± SD of the toric/non-toric groups were -0.61 ± 0.43/-1.45 ± 0.98 D (all eyes), -0.58 ± 0.42/-1.14 ± 0.70 D (T3), -0.59 ± 0.42/-1.63 ± 0.99 D (T4), and -0.67 ± 0.47/-2.18 ± 1.27 D (T5). The respective logarithm of the minimum angle of resolution UDVA values was 0.00 ± 0.12/0.16 ± 0.20 (all eyes), 0.00 ± 0.11/0.13 ± 0.18 (T3), 0.00 ± 0.13/0.25 ± 0.23 (T4), and 0.00 ± 0.11/0.17 ± 0.16 (T5). The toric group had better cylinder and UDVA outcome values; the difference between the groups reached significance (p<0.0001). In the toric group, the IOL rotation after implantation was 4.3 ± 4.0 degrees. Conclusion:Toric IOLs reduced the residual refractive cylinder in cases with corneal astigmatism between 0.75 and 3.00 D, and this effect was similar among different toric models. Toric IOLs are useful to improve the UDVA after cataract surgery.

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Effect of axis orientation on visual performance in astigmatic eyes

Abstract: No author has a financial or proprietary interest in any material or method mentioned.

Cited by 60 publications

References 26 publications

Longitudinal Change and Stability of Refractive, Keratometric, and Internal Astigmatism in Childhood

Longitudinal Change and Stability of Refractive, Keratometric, and Internal Astigmatism in Childhood

Influence of different types of astigmatism on visual acuity

Comparison between Toric and Non-Toric Intraocular Lenses in Patients with Corneal Astigmatism: A One-Year Multicenter Study

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