Ophthalmology
Refractive surgery resources from the Ophthalmology Hyperguide.
LASIK has been well accepted as the surgical standard of care for the correction of refractive error. Unlike phacoemulsification for cataract surgery, which has relatively well-established application guidelines for its…
Presbyopia is the gradual, age-related loss of accommodation. Unlike other refractive errors, presbyopia affects everyone at some point in his or her lifetime. Understanding the cause of this inevitable phenomenon…
Age-related changes in a normal cornea present issues for potential refractive surgery patients of all ages. These issues include whether corneal-based procedures are safe in young people, if older patients respond…
Lamellar corneal surgery originated in the pioneering works of Jose Ignacio Barraquer, MD, who was the first to report on both the theoretical and practical use of this surgical approach to modify the refractive state…
Ultra-short pulsed femtosecond (FS) lasers (Intralase, Irvine, Calif. and Femtec, 2010 Perfect Vision, Germany) now offer an alternative to blade-assisted mechanical microkeratomes for the creation of lamellar…
Incisions, laser ablation, and heat have been used to modify corneal curvature for the correction of refractive error and various pathological conditions. Excimer laser ablation of the corneal periphery in the form of…
Corneal topography was developed as the result of several progressively more sophisticated technical innovations over the past century and a half. The roots of videokeratoscopy extend back to the first keratometer,…
As refractive surgery has grown in popularity over the last decade, the types of surgical options available to correct a patient’s refractive error have also increased in number and become more complex. A recent annual…
It is important for refractive surgeons to be aware that all LASIK procedures affect the ocular surface and tear film dynamics. The LASIK procedure may have an impact on corneal sensation, aqueous tear production, and…
The variety of commercially available excimer laser systems has grown in proportion to the popularity of laser in situ keratomileusis (LASIK). Millions of these surgeries are expected to be performed worldwide in the…
Keratoconus and pellucid marginal degeneration (PMD) are progressive corneal diseases with bilateral corneal thinning that result in corneal distortion and reduced vision. A typical clinical presentation is shown in…
Mild to moderate degrees of hyperopia can be successfully managed with currently available surgical techniques, including tissue removal procedures (e.g., photorefractive keratectomy [PRK] and laser in situ…
In this tutorial, we discuss the importance of objective vertex distance measurements in achieving the most accurate refractive surgical results.
The cornea, being the principal refractive element of the eye, has been the focus of the refractive surgeon’s attention in an attempt to correct refractive errors. Contemporary refractive surgical methodologies aimed at…
Buttonhole flaps (Slide 1), especially thin flaps, are one of the more common LASIK flap-related intraoperative complications encountered, with incidence ranging from 0.1% to 0.2% depending on surgeon experience.1-6 In…
Keratoconus is a progressive disorder of noninflammatory corneal thinning in which the stroma assumes a conical shape, leading to myopia and irregular astigmatism, and mild-to-marked impairment in quality of vision.…
Clinical experience with photorefractive keratectomy (PRK) since its initial U.S. Food and Drug Administration (FDA) approval in 1995 has confirmed the safety and efficacy of the procedure in treating low to moderate…
Close attention to detail is crucial for a surgeon when performing laser in situ keratomileusis (LASIK). In this manner, the surgeon can anticipate and avoid potential complications. This discussion reviews the common…
Close attention to detail is crucial for a surgeon when performing laser in situ keratomileusis (LASIK). In this manner, the surgeon can anticipate and avoid potential complications. This discussion reviews the common…
LASIK's success as a surgical means of correction of refractive error is due in part to the low complication rate associated with this procedure. Many of the complications associated with the procedure are associated…
The form of optical correction chosen by an individual reflects his or her lifestyle including occupational and recreational needs. As such, a patient who is active in sports and outdoor activities that require…
Multifocal intraocular lenses (IOLs) are designed to address both aphakia that is surgically induced during cataract surgery and the loss of accommodation that accompanies the use of monofocal IOLs. When inserted at the…
Accommodation allows the phakic eye to change focus from distant objects to closer objects. During accommodation, an interaction between the ciliary muscle and the crystalline lens allows the required optical power…
Since the introduction of corneal lamellar refractive surgery, complications unique to the creation of the flap have been a concern.1-5 Operative complications related to the lamellar flap include striae, epithelial…
The treatment of high refractive error presents unique challenges to refractive surgeons. In keratorefractive surgery, the anterior corneal curvature is altered to change the conjugation point of the eye. However, a…
Photorefractive keratectomy (PRK) is a corneal-based refractive surgical procedure designed to reduce reliance on spectacles or contact lenses.1,2 PRK is approved by the Food and Drug Administration to treat all aspects…
Excimer laser phototherapeutic keratectomy (PTK) was approved by the U.S. Food and Drug Administration (FDA) in 1995 for the treatment of recurrent corneal erosions, irregular astigmatism, and elevated epithelial or…
Mycobacterium chelonai is a rapidly growing nontuberculous mycobacterium omnipresent in soil, food, and tap and laboratory water.1-4 It is a member of the M. fortuitum complex that is also composed of M. fortuitum and…
Clinician-patient communication is important to ensure a satisfactory outcome for refractive surgery. Clinicians can educate and counsel patients regarding alternatives to refractive surgery, as well as the risks and…
Myopia affects approximately 25% of adults in the United States. Approximately 10% of the myopic population can be expected to have visually significant astigmatism of more than 1 D. With recent technological advances,…
Before the advent of small-incision cataract surgery, a primary goal of cataract surgery was the prevention and postoperative management of unwanted corneal astigmatism. With the introduction of astigmatically neutral,…
Refractive surgery over the past decade has been the fastest-growing segment of the ophthalmic market. Clinicians continue to gain greater experience with the current technology and procedures even as new innovations…
Excimer lasers used in photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) emit a wavelength of 193 nm.1 The concerns over these ultraviolet (UV) laser systems include high investment and…
What differentiates the cornea from materials such as a contact lens? The cornea is an elastic collagen lamellar structure, the curvature of which is maintained firmly and constant by IOP. It is not difficult to imagine…
LASIK has become the most commonly performed surgical procedure for the correction of refractive error. Limitations to LASIK exist, especially in higher refractive errors in which patients can experience reduced…
Before the advent of wavefront technologies, refractive error was measured by only three parameters: sphere, cylinder, and axis. Wavefront analysis has facilitated the evaluation of the eye's entire refractive status to…
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