2020–2021 BCSC Basic and Clinical Science Course™
3 Clinical Optics
Chapter 7: Optical Considerations in Keratorefractive Surgery
Highlights
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The normal human cornea has a prolate shape that reduces spherical aberration.
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Keratorefractive surgical procedures modulate the shape of the cornea to reduce refractive error but can induce irregular astigmatism.
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New algorithms for excimer procedures have dramatically decreased the incidence and severity of night vision problems.
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The diagnosis of irregular astigmatism is made by meeting clinical and imaging criteria: loss of spectacle best-corrected vision but preservation of vision with the use of a gas-permeable contact lens, coupled with topographic corneal irregularity.
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Irregular astigmatism can frequently be understood in terms of basic aberration types, of which as few as 5 are of clinical interest. Aberrations are also conveniently described in terms of Zernike polynomials.
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Appropriate identification of preoperative irregular astigmatism is critical in keratorefractive surgery to optimize the visual result.
Excerpted from BCSC 2020-2021 series : Section 3 - Clinical Optics. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.