Biomaterial Database

Funduscopic systems: magnification in ametropia and aphakia. 1985

T Raasch

The magnification of the fundus image with various forms of funduscopy in ametropia and aphakia is poorly understood. This paper investigates these relationships. Direct and indirect ophthalmoscopy and biomicroscopic funduscopy is included. The Gullstrand Simplified Schematic Eye is modified by changing either the axial length, the power of the cornea, or the index of refraction of the lens to produce ametropia. Aphakia is produced by considering these same eyes with the crystalline lens removed. The magnification of these various eye/funduscope systems is presented, along with general principles illustrated by the figures.

UI	MeSH Term	Description	Entries
D006956	Hyperopia	A refractive error in which rays of light entering the eye parallel to the optic axis are brought to a focus behind the retina, as a result of the eyeball being too short from front to back. It is also called farsightedness because the near point is more distant than it is in emmetropia with an equal amplitude of accommodation. (Dorland, 27th ed)	Farsightedness,Hypermetropia
D007089	Image Enhancement	Improvement of the quality of a picture by various techniques, including computer processing, digital filtering, echocardiographic techniques, light and ultrastructural MICROSCOPY, fluorescence spectrometry and microscopy, scintigraphy, and in vitro image processing at the molecular level.	Image Quality Enhancement,Enhancement, Image,Enhancement, Image Quality,Enhancements, Image,Enhancements, Image Quality,Image Enhancements,Image Quality Enhancements,Quality Enhancement, Image,Quality Enhancements, Image
D007909	Lenses	Pieces of glass or other transparent materials used for magnification or increased visual acuity.
D009216	Myopia	A refractive error in which rays of light entering the EYE parallel to the optic axis are brought to a focus in front of the RETINA when accommodation (ACCOMMODATION, OCULAR) is relaxed. This results from an overly curved CORNEA or from the eyeball being too long from front to back. It is also called nearsightedness.	Nearsightedness,Myopias,Nearsightednesses
D012030	Refractive Errors	Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.	Ametropia,Refractive Disorders,Ametropias,Disorder, Refractive,Disorders, Refractive,Error, Refractive,Errors, Refractive,Refractive Disorder,Refractive Error
D005654	Fundus Oculi	The concave interior of the eye, consisting of the retina, the choroid, the sclera, the optic disk, and blood vessels, seen by means of the ophthalmoscope. (Cline et al., Dictionary of Visual Science, 4th ed)	Fundus of the Eye,Ocular Fundus,Fundus, Ocular
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001035	Aphakia	Absence of crystalline lens totally or partially from field of vision, from any cause except after cataract extraction. Aphakia is mainly congenital or as result of LENS DISLOCATION AND SUBLUXATION.	Aphakic Eye,Aphakic Eye, Post-traumatic,Aphakic Eye, Traumatic,Aphakias,Aphakic Eye, Post traumatic,Aphakic Eyes,Aphakic Eyes, Post-traumatic,Eye, Aphakic,Eye, Traumatic Aphakic,Post-traumatic Aphakic Eye,Post-traumatic Aphakic Eyes,Traumatic Aphakic Eye,Traumatic Aphakic Eyes
D019721	Ophthalmoscopes	Devices for examining the interior of the eye, permitting the clear visualization of the structures of the eye at any depth. (UMDNS, 1999)	Funduscopes,Funduscope,Ophthalmoscope