The Optical Design of the Human Eye: a Critical Review

Abstract

Cornea, lens and eye models are analyzed and compared to experimental findings to assess properties and eventually unveil optical design principles involved in the structure and function of the optical system of the eye. Models and data often show good match but also some paradoxes. The optical design seems to correspond to a wide angle lens. Compared to conventional optical systems, the eye presents a poor optical quality on axis, but a relatively good quality off-axis, thus yielding higher homogeneity for a wide visual field. This seems the result of an intriguing combination of the symmetry design principle with a total lack of rotational symmetry, decentrations and misalignments of the optical surfaces (J Optom 2009;2:3-18 ©2009 Spanish Council of Optometry) KEY WORDS: human eye's optical design; eye models; design principles; ocular aberrations; optical quality of the eye. RESUMENEn este trabajo, los modelos de córnea, de cristalino y de ojo se analizan y se comparan con los datos experimentales para evaluar las propiedades y, eventualmente, para desvelar los principios del diseño óptico que afectan a la estructura y al funcionamiento del sistema óptico del ojo humano. A menudo encontramos una coincidencia razonable entre los modelos y los datos experimentales, pero también se ponen de manifiesto algunas paradojas. El diseño óptico parece corresponderse con el de un gran angular. En comparación con los sistemas ópticos convencionales, el ojo tiene una mala calidad óptica en eje pero, por el contrario, presenta una calidad relativamente buena fuera de eje, proporcionando así una gran homogeneidad a una amplia extensión del campo visual. Este hecho parece ser el resultado de una curiosa combinación del principio de diseño simétrico con una total ausencia de simetría de rotación, con descentramientos y con una deficiente alineación de las superficies ópticas. (J Optom 2009;2:3-18 ©2009 Consejo General de Colegios de Ópticos-Optometristas de España) PALABRAS CLAVE: diseño óptico del ojo humano; modelos de ojo; principios de diseño; aberraciones oculares; calidad óptica del ojo.

Assessment of minimum permissible geometrical parameters of a near-to-eye display

“…Many of the proposrd models of the human eye often show good much with experimental data but still some discrepancies exist [12,13]. There is no a universal model [13]. On the other hand, these discrepancies are associated with the wide angle viewing [12,13] that is not considered in the paraxial approximation.…”

“…There is no a universal model [13]. On the other hand, these discrepancies are associated with the wide angle viewing [12,13] that is not considered in the paraxial approximation. Moreover, by studying a paraxial image formation, it is not necessary to take into account variations of the refractive indexes in the real human eye [12][13][14][15].…”

“…Optics of the human eye has been a subject of intensive investigations since development of optical instruments. Many of the proposrd models of the human eye often show good much with experimental data but still some discrepancies exist [12,13]. There is no a universal model [13].…”

“…A great variety of models describing the optics of the human eye, which itself poses a formidable challenge and is a complex optical system with evolutionary optimized design, have been proposed [12][13][14][15]. The variety of the models reflects the fact that all they are incomplete.…”

The Individual Virtual Eye: a Computer Model for Advanced Intraocular Lens Calculation

“…Surface elevation and normals can be evaluated efficiently at any position algebraically. This modeling represents only a rough approximation to a human crystalline lens, which has a non-homogeneous gradient index 69 -however most kinds of artificial lenses can be specified this way, including toric and aspheric lenses.…”