OPTM2133 Lecture Notes - Lecture 1: Retinoscopy, Autorefractor, Refractive Error
Document Summary
Projector chart: measures va (resolving ability of a person given by a number, wall chart (most basic), self-illuminated chart (translucent; backlit), led. Room size from subject is less of problem. Illumination of room doesn"t affect measurements: wear and tear. Power of the lens never changes -> l value changes. Beam splitter - fenestrated (small centre hole) vs semi-reflecting/silvered mirror. Scopes retina to find refractive error of person. Retinoscope: objective refraction to get a start value. Indirect - form an image of persons retina and look at this image. Converges divergent rays coming out of instrument onto retina. Patch of illuminated retina (diverging rays) from patient"s retina and forms image (this is the one practitioner sees) Light from top: used to look at retina. Illumination system: has to be alignment of illumination and observation system (only point where you"ll see retina, myopes - view of retina is smaller. Slitlamp biomicroscope: optic section through cornea and lens, magnifies anterior structure.
