Advanced Geometric Optics
In this tutorial, a few concepts regarding the way light rays interact with thick lenses, that is, real lenses we use, are discussed. Next, the different kinds of magnification of images produced by lenses and the…
Ophthalmology
Clinical ophthalmology
Clinical ophthalmology resources from the Ophthalmology Hyperguide.
23 resourcesAlphabetical A–Z
Anisometropia
Anisometropia is an unequal refractive error in both eyes of an individual. Because truly identical refractive errors in eyes is not the norm, clinical usage of the term anisometropia is reserved for patients with…
Basic Geometric Optics
In order to understand the way light behaves, it is best to divide its properties into two different realms. For example, physical optics helps to explain how light has different colors, how lasers produce such energy,…
Corneal and External Disease from Light Injury
Although ocular exposure to light is an obvious necessity for sight, it has been implicated as a causative element in a host of disorders of the human eye, involving structures including the cornea and ocular surface,…
Functional Impact of Visual Loss in the Aged Patient
The aging population in the United States will cause a demographic shift in medical care. The aging boom is due in part to the increase in average life expectancy (75.5 years in 1991) and the aging of post-World War II…
Lasers
The word laser is an acronym for light amplification by stimulated emission of radiation. Lasers operate in the quantum world of atoms and photons. Three concepts involving the interaction between photons and atoms are…
Lasers in the Treatment of Anterior Segment Disorders
Ophthalmic lasers are used to treat a variety of anterior segment disorders. The anterior segment tissues that can undergo laser treatment include the cornea, iris, trabecular meshwork (TM), lens capsule, and ciliary…
Optics of Contact Lenses
Contact lenses are made from a variety of polymers that can be separated into two broad categories: soft, or hydrogel, lenses and rigid lenses.
Optics of Human Eyes
Light focused by the human eye is refracted by multiple curved surfaces before falling on the retina, where an electrical impulse is generated, eventually perceived as vision. The corneal tear film, corneal layers, and…
Optics of Intraocular Lenses
The implantation of intraocular lenses (IOLs) following removal of a cataractous crystalline lens is one of the most common surgical procedures performed in the United States. From an optical standpoint, the typical…
Optics of Refractive Surgery
In the past decade, refractive surgery has become a widespread means for reducing refractive error in the adult population. The two most prevalent techniques are incisional surgeries, such as radial keratotomy (RK) and…
Prisms and Mirrors
Light passing through a flat (planar) interface between media of different refractive indices is refracted without change of vergence. At a curved surface, vergence would be altered. If an optical medium is limited by…
Progressive Addition Lenses
With age, people become presbyopic (i.e., experience loss in power of accomodation). Reading small print, performing operations on small objects, or working with detailed technical drawings may become difficult. Reading…
Retinal Disease and Light Exposure
Although ocular exposure to light is an obvious necessity for sight, it has been implicated as a causative element in a host of disorders of the human eye, involving structures including the cornea and ocular surface,…
Retinal Lasers: Laser Types, Instrumentation, Uses, and Tissue Interactions
Meyer-Schwickerath has been credited with early attempts at retinal photocoagulation; first with sunlight in 1946, then with his development of the xenon-arc lamp in 1956.1 The first ophthalmic laser was developed by…
Retinoscopy
Retinoscopy is an objective method of determining a patient's refractive error. Although some degree of patient cooperation is needed, no subjective responses from the patient are necessary. The accuracy of the…
Subjective Refraction Part I
Accuracy in objective refraction (retinoscopy) relies on the retinoscopist's abilities or the autorefractor's software. However, subjective refraction involves complex interaction between a refractionist and a patient…
Subjective Refraction Part II
To ensure that accommodation does not degrade the results of refraction, it is sometimes necessary to eliminate the patient’s ability to accommodate, albeit temporarily. Cycloplegic eye drops provide an anticholinergic…
Subjective Refraction, Part I
Accuracy in objective refraction (retinoscopy) relies on the retinoscopist's abilities or the autorefractor's software. However, subjective refraction involves complex interaction between a refractionist and a patient…
Subjective Refraction, Part II
To ensure that accommodation does not degrade the results of refraction, it is sometimes necessary to eliminate the patient’s ability to accommodate, albeit temporarily. Cycloplegic eye drops provide an anticholinergic…
The Care and Management of a Dissatisfied Refraction Patient
It is a truism that, "If you operate, you will have complications." Wise surgeons plan ahead to avoid complications and to manage those that unavoidably occur. Also a truism - clinicians who prescribe glasses will have…
The Physics of Light
Vision is the perception of light. To comprehend the nature of human vision, an understanding of the properties of light is necessary. Many of the technologies used for examining the eye and treating ocular disease take…
Visual Acuity
The measurement of visual acuity enables physicians to communicate with the patient, as well as other physicians, the level of preservation or degradation of vision. Visual acuity serves as a report card for the…
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