Archive | November 2010

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Chapter 20 – LASIK: Indications and Techniques

Chapter 20 – LASIK: Indications and Techniques JOHN F. DOANE STEPHEN G. SLADE DEFINITION • LASIK stands for laser in situ keratomileusis, in which an anterior flap of cornea is lifted with a keratome and an excimer laser is used to sculpt the stromal bed to change the refractive error of the eye. KEY FEATURES […]

Chapter 19 – Automated and Manual Lamellar Surgical Procedures and Epikeratoplasty

Chapter 19 – Automated and Manual Lamellar Surgical Procedures and Epikeratoplasty SHU-WEN CHANG DIMITRI T. AZAR DEFINITION • Lamellar refractive surgery comprises various surgical procedures that entail lamellar dissection of the cornea and reshaping the corneal stroma to correct refractive errors of the eye. KEY FEATURES • Usually employed to correct high myopia or hyperopia. […]

Chapter 18 – Excimer Laser Photorefractive Keratectomy (PRK)

Chapter 18 – Excimer Laser Photorefractive Keratectomy (PRK) WILLIAM J. LAHNERS DAVID R. HARDTEN DEFINITION • Photorefractive keratectomy (PRK) is a procedure in which the cornea is reshaped using an excimer laser. The procedure is designed to reduce the patient’s dependence on glasses or contact lenses. The excimer laser has revolutionized the field of refractive […]

Chapter 17 – Radial and Astigmatic Keratotomy

Chapter 17 – Radial and Astigmatic Keratotomy KERRY K. ASSIL MARK A. ROTHSTEIN HISTORICAL REVIEW Incisional Keratotomy The Dutch ophthalmologist Snellen[1] (1834–1908) proposed, in his 1869 thesis on the surgical correction of astigmatism, that incisions within the steep corneal meridian might affect astigmatic magnitude. In 1885, Schiøtz,[2] a Norwegian ophthalmologist, confirmed Snellen’s hypothesis when he […]

Chapter 16 – Preoperative Evaluation for Refractive Surgery

Chapter 16 – Preoperative Evaluation for Refractive Surgery JOSHUA A. YOUNG ERNEST W. KORNMEHL PREOPERATIVE WORK-UP • Preoperative work-up consists of a sequence—screening, preoperative examination, and counseling. PATIENT SELECTION • Important factor that determines the likelihood of success in refractive surgery. • Improper preoperative evaluation may result in: • Treatment of patients who should not […]

Chapter 15 – Current Concepts, Classification, and History of Refractive Surgery

Chapter 15 – Current Concepts, Classification, and History of Refractive Surgery JUAN CARLOS ABAD DIMITRI T. AZAR DEFINITION • Refractive surgery is an evolving field of ophthalmology focusing on the correction of refractive errors of the eye, including myopia, hyperopia, astigmatism, and presbyopia. KEY FEATURES • Realistic patient expectations. • Stable preoperative refraction. • Absence […]

Chapter 14 – Perspectives in Aberrations of the Eye

Chapter 14 – Perspectives in Aberrations of the Eye EDMOND H. THALL PAVIKA THAMMANO RUSSELL MILLER DEFINITION • Optical aberrations refer to specific defects in an optical system that diminish the resolution of an image. The eye, like any other optical system, suffers from a number of specific aberrations. KEY FEATURES • Understanding of the […]

Chapter 13 – Ophthalmic Instrumentation

Chapter 13 – Ophthalmic Instrumentation DAVID MILLER EDMOND H. THALL NEAL H. ATEBARA KEY FEATURES • The ability of a transparent medium to bend a ray of light is the basis for most of the instruments used in ophthalmology today. • Spherical lenses, prisms, mirrors, slit-shaped illumination, astronomical and Galilean telescopes, and a multitude of […]

Chapter 12 – Contact Lenses

Chapter 12 – Contact Lenses PAUL F. WHITE CLIFFORD A. SCOTT DEFINITION • Contact lenses are visual devices that provide an artificial anterior refracting surface to the human eye and are used for corrective, cosmetic, and therapeutic purposes. KEY FEATURES • Lenses are made from various soft and rigid materials and are configured in a […]

Chapter 11 – Subjective Testing of Refraction

Chapter 11 – Subjective Testing of Refraction CLIFFORD A. SCOTT DEFINITION • The neutralization of an individual’s refractive error using a variety of tests in which the patient’s responses determine the lens power that best produces a sharply focused image on the retina. • The selection of a prescription for corrective lenses that balances optical […]