2 Practice of Retinoscopy Importance of art & science of refractionMastery over the principles & practiceNearly 15 million visually impairedRefractive errors constitutes 10% of blindness second only to cataractEarly detection, precise estimation , optimum correction is essential
3 Importance of Retinoscopy Restoration of visionPrevention of strabismus & amblyopiaChildren with poor vision wrongly dubbed dyslexic & mentally retardedGood vision helps in mental, social, emotional and psychological development and scholastic pursuitsRefraction accounts for more than 50% of ophthalmic OPD work
4 Retinoscopy Objective method of estimation of ref status Can be done with out cycloplegics (dry refraction)-Will be fallacious – latent & facultative : missedPrecise assessment of astigmatism & axes difficultDifficult in children, uncooperative patients & small pupils(old & DM) opacities in MediaCycloplegic refraction essential in children, strabismus
5 Retinoscopy… Cycloplegic refraction essential when Objective refraction does not tally with subjective acceptance, clarity , comfortPts’ symptoms out of proportion to abs. fraction of manifest errorBest cycloplegic – short acting, quick acting, effective, adequate duration , good safety profile, good shelf life, cost factor , side effects
7 Equipment requiredLister’s bulb, retinoscope, trial frame, trial lenses, occluder , pin hole, dark room, VT chartsOphthalmologist/ refractionist sits at 1 mtPts ‘ accommodation relaxed – pupil dilatedListers bulb placed behind, above & to one side of pts’ headRetinoscope mirror reflects light to pts’ eye
8 Retinoscopy Procedure Begins with directing light into pts’ eye and illuminating area of retinaEmergent rays from pts eye forms an imageIt is referred to as red fundal glowBy convention referred to patients’ pupillary areaFormed at far point (at infinity) of pts eye in emmetropia, in front of pts’ eye in myopia and behind pts’ eye in hypermetropia
9 Retinoscopy Procedure… Moving the light across the pts’ retina & observing the movement of the fundal glow- ref status is assessedWith suitable lenses, movement of fundal glow is neutralized & error estimated
10 Retinoscopy Procedure… If fundal glow moves with the mirror(plane), neutralized with plus lensesIf fundal glow moves against the mirror – neutralized with minus lensesPoint of neutralization – no movement of fundal glow will be seen, cross checked with concave mirrorUltimately pt of neutralization is to achieve 1.0D myopia using suitable lenses
11 Retinoscopy Procedure… Two meridians (vertical & hori) checked to take care of astigmatismBoth eyes checked to take care of anisometropiaConcentrate on pupillary zone(corneal centre), avoid extreme periphery
12 Calculations Distance (1 mt) factor- 1.0D Cycloplegic D, to be deduced 1.5DEg.-2.0DTo be deducted : 1.5D-2.0D-3.5DRef error: -3.5D sph-3.5D
16 After calculations- transcribe into spectacle format If pt is over 40 yrs ,near vision additionat 40 yrs- +1.0D , add 0.5D for every 5 yrs upto 60 yrsInstead of Lister’s bulb & mirror,self illuminated streak retinoscope can be usedWith advent of autorefractometer craze for computer testing, art of retinoscopy is dyingWith skill, patience & perseverance it is the best method for estimation of ref errors.
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