retinoscope, optom faslu muhammed

RETINOSCOPY OPTOM FASLU MUHAMMED

It’s a method to evaluate the refractive error of an eye objectively by utilizing the technique of neutralization.

We evaluate the eye as an optical instrument, ignoring any information the eye transmit to the brain. Retinoscopy does not depend on the patient’s vision or judgment.

PRINCIPLE It is based on the fact that when light is

reflected from mirror in to the eye the direction in which the light will travel across the pupil will depend up on the refractive state of the eye.

Bring pts FP to retinoscope peep hole. Emmetropia:infinity hyperopia:beyound infinity Myopia:less than infinity

The first objective diagnosis of refractive error was by French Ophthalmologist “F. Cuignut”

“Father of Retinoscopy”

Jack C. Copeland, the father of Streak Retinoscope, who developed the Retinoscope and spent his life teaching its use”

EVOLUTION

Skiascopy Dioptroscopy Pupilloscopy Korescopy Umbrascopy Scotoscopy

Types Of Retinoscope:A)Reflecting(mirror) retinoscopes:

*Cheap & the most commonly employed

*A source of light is required,which is kept above & behind the head of the patient.

*The source of light used should be small,bright & enclosed.

*A mirror retinoscope may consist of a single plane mirror or a combination of plane and concave mirrors(Priestley-Smith’s mirror)

A BMirror retinoscopes: A)Plane mirror; B)Priestley-smith’s mirror

*The central aperture in the mirror should be 3-4mm in diameter so that a sufficient amount of light can enter the observer’s eye.

B)Self-illuminated retinoscopes:*Costly but handy*2 types: (i)a spot retinoscope (ii)a streak retinoscope

(ii)a.Heine streak retinoscope b.Welch allen streak retinoscope

(i)A spot retinoscope

Spot retinoscopes:*It consists of a bulb with a tiny wired filament about 1-2 mm in size.

Streak retinoscopes: In streak retinoscope the illumination is

provided by a special bulb that has a straight filament.

It is more sensitive than spot retinoscope in detecting astigmatism. It is provided by a special bulb that a straight filament,thus forming a ‘streak’ in projection.

SURFACE ANATOMY

PROJECTION SYSTEM

PROJECTION SYSTEM

OBSERVATION SYSTEM

PREREQUISITES FOR RETINOSCOPY 1. dark room 2.Trial set 3.Trial frame 4.Phoropter/refractor 5.Distance target 6.Retinoscope

PROCEDURE Patient is made to sit at a distance of 1m,67 cm,

50 cm.. from the examiner. With the help of a retinoscope, light is thrown onto

the patient’s eye. Who is instructed to look at a farpoint (to relax

accommodation).

Through the hole of retinoscope , the examiner observes a red reflex in the pupillary area of the patient.

Move the retinoscope in horizontal and vertical meridia.

Neutralise the reflex

THE CHARACTERISTICS OF THE MOVING RETINAL REFLEX ARE AS FOLLOWS:

Speed and brilliance. Width of reflex. In the presence of astigmatism.

STATIC VERSUS DYNAMIC RETINOSCOPY Static:procedure performed without active

use of accommodation Dynamic:with active use of accommodation

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