Biomaterial Database

Vision with bifocal intraocular lenses. 1993

M C Knorz

Universitäts-Augenklinik, Klinikum Mannheim, Germany.

The laboratory and clinical results of tests of different bifocal intraocular lenses (BIOLs) are compared. Included are two-zone refractive BIOLs with a central near zone and an annular distance zone (group 1); three-zone refractive BIOLs with a central distance zone, an annular near zone, and a peripheral distance zone (group 2); diffractive BIOLs (group 3); multizone refractive BIOLs (group 4); and other BIOLs (group 5). All BIOLs cause a significant loss of image contrast and acuity at low contrast. The incidence of visual side effects (e.g., halos, glare) varies but is significantly higher than that obtained with monofocal IOLs. On the other hand, BIOLs provide a depth of focus of 3-4 D as compared with only 1.5 D for monofocal IOLs. In group 1, distance vision is reduced in bright light, which limits the clinical use of these BIOLs. In group 2, distance vision is better than near vision. Thus, a temporary near add is required in some cases. In group 3, distance and near vision are similar, but the incidence of visual side effects is higher than that in group 2. Only BIOLs of groups 2 and 3 can be recommended for clinical use in selected patients. Not enough data are currently available on the other groups. Patient selection is the most critical factor for BIOLs. Ideal patients are relatively young and active, are highly motivated, show no ocular pathology, and have a normal pupil, an axial length of 22-24.5 mm, and a corneal astigmatism of less than 1 D. Reduced image contrast, mainly at near focus, and visual side effects must be acceptable. Bilateral implantation yields the best results. A monofocal fellow eye is a definite contraindication. In summary, BIOLs cannot replace monofocal IOLs. However, they provide a valuable alternative in selected patients.

UI	MeSH Term	Description	Entries
D007910	Lenses, Intraocular	Artificial implanted lenses.	Implantable Contact Lens,Lens, Intraocular,Contact Lens, Implantable,Intraocular Lens,Intraocular Lenses,Lens, Implantable Contact
D010358	Patient Participation	Patient involvement in the decision-making process in matters pertaining to health.	Patient Activation,Patient Empowerment,Patient Engagement,Patient Involvement,Patient Participation Rates,Activation, Patient,Empowerment, Patient,Engagement, Patient,Involvement, Patient,Participation Rate, Patient,Participation Rates, Patient,Participation, Patient,Patient Participation Rate
D011474	Prosthesis Design	The plan and delineation of prostheses in general or a specific prosthesis.	Design, Prosthesis,Designs, Prosthesis,Prosthesis Designs
D003867	Depth Perception	Perception of three-dimensionality.	Stereopsis,Stereoscopic Vision,Depth Perceptions,Perception, Depth,Perceptions, Depth,Stereopses,Stereoscopic Visions,Vision, Stereoscopic,Visions, Stereoscopic
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000065	Accommodation, Ocular	The dioptric adjustment of the EYE (to attain maximal sharpness of retinal imagery for an object of regard) referring to the ability, to the mechanism, or to the process. Ocular accommodation is the effecting of refractive changes by changes in the shape of the CRYSTALLINE LENS. Loosely, it refers to ocular adjustments for VISION, OCULAR at various distances. (Cline et al., Dictionary of Visual Science, 4th ed)	Accommodation, Lens,Ocular Accommodation,Ocular Distance Accommodation,Accommodation, Ocular Distance,Distance Accommodation, Ocular,Lens Accommodation,Ocular Distance Accommodations
D012641	Selection, Genetic	Differential and non-random reproduction of different genotypes, operating to alter the gene frequencies within a population.	Natural Selection,Genetic Selection,Selection, Natural
D014785	Vision, Ocular	The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.	Vision,Light Signal Transduction, Visual,Ocular Vision,Visual Light Signal Transduction,Visual Phototransduction,Visual Transduction,Phototransduction, Visual,Transduction, Visual
D014786	Vision Disorders	Visual impairments limiting one or more of the basic functions of the eye: visual acuity, dark adaptation, color vision, or peripheral vision. These may result from EYE DISEASES; OPTIC NERVE DISEASES; VISUAL PATHWAY diseases; OCCIPITAL LOBE diseases; OCULAR MOTILITY DISORDERS; and other conditions (From Newell, Ophthalmology: Principles and Concepts, 7th ed, p132).	Hemeralopia,Macropsia,Micropsia,Day Blindness,Metamorphopsia,Vision Disability,Visual Disorders,Visual Impairment,Blindness, Day,Disabilities, Vision,Disability, Vision,Disorder, Visual,Disorders, Visual,Hemeralopias,Impairment, Visual,Impairments, Visual,Macropsias,Metamorphopsias,Micropsias,Vision Disabilities,Vision Disorder,Visual Disorder,Visual Impairments
D014792	Visual Acuity	Clarity or sharpness of OCULAR VISION or the ability of the eye to see fine details. Visual acuity depends on the functions of RETINA, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast.	Acuities, Visual,Acuity, Visual,Visual Acuities