2020–2021 BCSC Basic and Clinical Science Course™
3 Clinical Optics
Chapter 7: Optical Considerations in Keratorefractive Surgery
The normal human cornea has a prolate shape that reduces spherical aberration.
Keratorefractive surgical procedures modulate the shape of the cornea to reduce refractive error but can induce irregular astigmatism.
New algorithms for excimer procedures have dramatically decreased the incidence and severity of night vision problems.
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.
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.
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.