Utility of an open field Shack-Hartmann aberrometer for measurement of refractive error in infants and young children

Harvey, Erin M.; Miller, Joseph M.; Schwiegerling, Jim

doi:10.1016/j.jaapos.2013.05.015

Cited by 6 publications

(4 citation statements)

References 55 publications

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“…Another potential limitation might be the lack of a cycloplegic procedure for the KR-1W measurement. Although cycloplegia provides more repeatable inter-visit results, this is mostly applicable for spherical power, and has only a subtle effect on cylindrical power [ 41 – 43 ]. However, the design of the study was not intended to compare values between visits, but rather to decompose the TA for each reading.…”

Section: Discussionmentioning

confidence: 99%

Ocular residual and corneal astigmatism in a clinical population of high school students

et al. 2018

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PurposeTotal refractive astigmatism is usually the first consideration that guides the selection of contact lens type (e.g., spherical or toric), while the ocular source of the astigmatism is a second, but more important consideration, for the final clinical decision. This study was conducted to provide detailed data on this topic by evaluating astigmatic components in Chinese adolescents.MethodsParticipants were recruited from healthy high school students undergoing an annual ocular examination at a local hospital. Total astigmatism (TA), corneal astigmatism (CA), and ocular residual astigmatism (ORA) were determined by a Hartmann-Shack wavefront analyzer system (KR-1W, Topcon) with the natural pupil. The axis relationship between CA and ORA was placed into three categories: on-axis, defined as an axis with a difference of 0 ± 10°; opposite-axis, a difference of 90 ± 10°; and the rest defined as oblique-axis.ResultsThe study consisted of 1,466 students (57.84% girls, age: 16.49 ± 1.05 years). ORA was present in 83.97%, 66.64%, and 45.23% of participants, according to the various criteria for astigmatism (≥ 0.50 D, ≥ 0.75 D, and ≥ 1.00 D, respectively). While with-the-rule was the most common axis orientation for both TA (76.28%) and CA (89.94%), against-the-rule predominated in ORA (93.82%; χ2 = 1688.544, p < 0.001). Opposite-axis was the major type of axis difference (90.96%) of clinical significance (i.e., ≥ 1.00 D) between CA and ORA, which also prevailed in all levels of TA (range: 56.25–82.26%).ConclusionsORA is common in high school students and usually demonstrates a compensation relationship with CA, which should be taken into consideration when determining the design of contact lenses to correct refractive error.

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Section: Discussionmentioning

confidence: 99%

Ocular residual and corneal astigmatism in a clinical population of high school students

et al. 2018

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“…At least 7 images were required for averaging within each subject. 14 The total root-mean-square (RMS) was calculated as the root of the sum of squared Zernike coefficients after scaling each observation to a 4 mm diameter pupil and averaging the coefficients within subjects. We also combined the individual Zernike coefficients related to coma (z07s and z08s) into a single unsigned RMS coma.…”

Section: Methodsmentioning

confidence: 99%

Higher-order aberrations and best-corrected visual acuity in Native American children with a high prevalence of astigmatism

Miller

Harvey

Schwiegerling

2015

Journal of American Association for Pediatric Ophthalmology and

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Purpose To determine whether higher-order aberrations (HOAs) in children from a highly astigmatic population differ from population norms and whether HOAs are associated with astigmatism and reduced best-corrected visual acuity. Methods Subjects were 218 Tohono O’odham Native American children 5–9 years of age. Noncycloplegic HOA measurements were obtained with a handheld Shack-Hartmann sensor (SHS). Signed (z06s to z14s) and unsigned (z06u to z14u) wavefront aberration Zernike coefficients Z(3,−3) to Z(4,4) were rescaled for a 4 mm diameter pupil and compared to adult population norms. Cycloplegic refraction and best-corrected logMAR letter visual acuity (BCVA) were also measured. Regression analyses assessed the contribution of astigmatism (J0) and HOAs to BCVA. Results The mean root-mean-square (RMS) HOA of 0.191 ± 0.072 μm was significantly greater than population norms (0.100 ± 0.044 μm. All unsigned HOA coefficients (z06u to z14u) and all signed coefficients except z09s, z10s, and z11s were significantly larger than population norms. Decreased BCVA was associated with astigmatism (J0) and spherical aberration (z12u) but not RMS coma, with the effect of J0 about 4 times as great as z12u. Conclusions Tohono O’odham children show elevated HOAs compared to population norms. Astigmatism and unsigned spherical aberration are associated with decreased acuity, but the effects of spherical aberration are minimal and not clinically significant.

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“…Any measure containing >2D cylinder was excluded from analysis as it was likely due to poor subject fixation based on findings that the increase in astigmatism resulting from accommodation is <2D, 15–17 and that the subjects in this experiment had low baseline amounts of uncorrected astigmatism in their habitual correction (mean −0.48±0.25D, range 0.00 to −1.27D).…”

Section: Methodsmentioning

confidence: 99%

Accommodative Gain in Relation to Perceived Target Clarity

Roberts¹,

Anderson

Stuebing³

2015

Optometry and Vision Science

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Purpose The purpose of this study is to determine the relationship between target clarity and the magnitude of accommodative lag using the metric accommodative gain (AG). Methods Monocular accommodative responses were measured with Grand Seiko autorefraction using both proximal and minus lens techniques in 139 subjects 5–35 years old. Subjects viewed a 1.5mm letter at 13 discrete distances (range = 40 – 3.33cm) for the proximal technique and fixed at 33cm through minus lenses of increasing power for the lens technique. Subjects were instructed to keep the target clear and report when it blurred. The AG was calculated (accommodative response / accommodative demand) for the four greatest consecutive demands perceived clear (termed conditions 1–4) and the first demand perceived blurry (termed condition 5). Results Multivariate planned contrast, including age as a predictor, revealed mean AG was significantly larger when the target was clear (range = 0.71 to 0.77 for conditions 1–4 across techniques) versus blurry (0.59 and 0.68 for condition 5 across techniques) (p<0.001 for proximal and p<0.036 for lens). Age was only a contributing factor for the proximal technique with youngest subjects having the largest decrease in AG when the target changed from clear to blurry (p=0.017). Conclusions These data suggest that across age and technique, the AG is relatively constant when the target is perceived clear, but drops below ~70%, on average, once the target is perceived as blurry for subjects ranging from 5 to 35 years of age. The AG may be a useful metric to compare accommodative responses across a range of demands and to identify accommodative responses which may not be sufficient to perceive a clear target.

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Utility of an open field Shack-Hartmann aberrometer for measurement of refractive error in infants and young children

Cited by 6 publications

References 55 publications

Ocular residual and corneal astigmatism in a clinical population of high school students

Ocular residual and corneal astigmatism in a clinical population of high school students

Higher-order aberrations and best-corrected visual acuity in Native American children with a high prevalence of astigmatism

Accommodative Gain in Relation to Perceived Target Clarity

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