Corneal and refractive changes due to orthokeratology

Mountford, John

doi:10.1016/b978-0-7506-4007-7.50009-x

Cited by 2 publications

(2 citation statements)

References 23 publications

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“…Sometimes we come across irregular astigmatism with different keratometry readings on topographer auto keratometer and IOL master [6][7][8]. If there is mild irregular astigmatism it can be dealt by taking the readings which agree most with each other and fed into equalant K program of Barrett's toric IOL calculator this will give the best suited toric model.…”

Section: Mini Reviewmentioning

confidence: 99%

Pearls for Refractive Cataract Surgery

Prateek¹

2018

OAJO

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Section: Mini Reviewmentioning

confidence: 99%

Pearls for Refractive Cataract Surgery

Prateek¹

2018

OAJO

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“…Tangential maps measure the true corneal curvature, while axial maps measure the radius of curvature with respect to the optical axis 30 . Refractive maps calculate the true corneal refractive power using Snell's law, and have been suggested to be the most accurate map for determining the TZ size, 31 although this has not been confirmed 30 . Whilst having limited accuracy to determine refractive power change, tangential subtractive maps provide sophisticated measurements of localised corneal changes and a better representation of the corneal shape after ortho‐k, 31 and thus, were used to evaluate TZ characteristics in the current study.…”

Section: Introductionmentioning

confidence: 99%

Manual and software‐based measurements of treatment zone parameters and characteristics in children with slow and fast axial elongation in orthokeratology

Guo

Cheung

et al. 2022

Ophthalmic Physiologic Optic

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To compare the treatment zone (TZ) measurements obtained using manual and software-based methods in orthokeratology (ortho-k) subjects and explore the TZ characteristics of children with slow and fast axial elongation after ortho-k. Methods: Data from 69 subjects (aged 7 to <13 years old), who participated in three 24-month longitudinal orthokeratology studies, showing fast (>0.27 mm, n = 38) and slow (<0.09 mm, n = 31) axial elongation, were retrieved. The TZ after ortho-k was defined as the central flattened area enclosed by points with no refractive power change. TZ parameters, including decentration, size, width of the peripheral steepened zone (PSZ), central and peripheral refractive power changes and peripheral rate of power change, were determined manually and using pythonbased software. TZ parameters were compared between measurement methods and between groups.Results: Almost all TZ parameters measured manually and with the aid of software were significantly different (p < 0.05). Differences in decentration, size and the PSZ width were not clinically significant, but differences (0.45 to 0.92 D) in refractive power change in the PSZ were significant, although intraclass coefficients (0.95 to 0.98) indicated excellent agreement between methods. Significantly greater TZ decentration, smaller TZ size and greater inferior rate of power change (relative to the TZ centre) were observed in slow progressors using both methods, suggesting a potential role of TZ in regulating myopia progression in ortho-k. Conclusion:TZ measurements using manual and software-based methods differed significantly and cannot be used interchangeably. The combination of TZ decentration, TZ size and peripheral rate of power change may affect myopia control effect in ortho-k.

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Corneal and refractive changes due to orthokeratology

Cited by 2 publications

References 23 publications

Pearls for Refractive Cataract Surgery

Pearls for Refractive Cataract Surgery

Manual and software‐based measurements of treatment zone parameters and characteristics in children with slow and fast axial elongation in orthokeratology

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