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Query: UMLS:C0086543 (cataract)
 29,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Three different components contribute to the modulation transfer function of the visual system: (1) formation of the optical image (refractive media, pupil); (2) scattering of light in the prereceptoral layers of the retina; (3) neuronal processing in the retina und superior visual centers. In the presence of media opacities or non-correctable refractive errors, the clinical question often arises as to which macular function can be expected under the assumption of normal optical image formation (e.g. prior to cataract extraction, corneal transplantation, or vitrectomy). Simple tests such as light projection, color discrimination, and two-point discrimination cannot provide adequate information about macular function. The same holds true for the global luminance ERG. The X-ray phosphene is obsolete. The Maddox rod (with limitations), transilluminated Amsler grid, and various entoptic phenomena (Purkinje vascular phenomenon, foveal chagrin, Haidinger's brushes, blue field phenomenon) are available as qualitative subjective tests. Maxwellian view systems with pinhole aperture (potential acuity meter PAM) and the interferometers (retinometer, visometer, SITE-IRAS interferometer) provide quantitative subjective methods. The flash VECP is primarily a qualitative objective test that allows semiquantitative acuity prediction under special conditions (unilateral opacities). Psychophysical criteria that are less affected by the quality of the retinal image show promising developments in future subjective tests, e.g. optotypes in positive contrast, optotypes or targets superimposed on a background of optical noise, or hyperacuity. Future objective test developments are pattern VECP or even pattern ERG elicited by interferometric stimulation, speckle VECP and focal ERG.
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PMID:[Predicting visual acuity in media opacities and uncorrectable refractive errors. Assessing so-called "retinal visual acuity"]. 208 91

Potential visual acuities were measured with the Randwal IRAS portable interferometer, with and without pupil dilation, on a sample of predominately elderly patients with mild to moderate cataract. No clinically significant difference was found between interferometer potential acuities before and after pupil dilation.
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PMID:Potential visual acuity measured with and without pupil dilation. 277 44

The preoperative testing of retinal acuity was evaluated using two instruments in each of 35 eyes having extracapsular cataract extraction. Retinal acuity was measured using the SITE IRAS hand-held interferometer and the Haag-Streit Lotmar visometer. The postoperative findings are given for comparisons of final acuity, prediction, and instrument evaluation. The results showed predicted acuity to be within two lines of the final acuity in 57.1% of eyes with the Haag-Streit unit and in 42.8% of eyes with the SITE instrument. The instrument differences were more in procedure than in results.
J Cataract Refract Surg 1988 Mar
PMID:Clinical comparison of the SITE IRAS hand-held interferometer and Haag-Streit Lotmar visometer. 335 57