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RetinoscopyDr Mohamed Adel Abdelshafik

Professor of ophthalmology – Ain Shams University Cairo Egypt

RetinoscopyRetinoscopy

Source of light

patientDoctormirror

Direction of mvt of mirror

Against No mvt With mvt

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- 2

- 2

0

0

+5

+5

- 4 - 2+ 3

We add – 2 on results :

• One for the distance of one meter • One for the tone of ciliary muscle if

atropine was used

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1

2

3

4

5

1

2

against

no mvt

3

4

5

with

with

with

no mvt

against

with

with

with

٤

no mvt

againstNo movement

with

with

with

No movement

No movement

No movement

no mvt

no mvt

no mvt

no mvt

no mvt

Far point

We add -1 D for the distance of one meter

Focal length

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Far point

+60 D

We add another -1 D for tone of CM if atropine was used during retinoscopy

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Source of light

As rays comes out from the eye parallelparallel---- with movement of RR

As rays comes out from the eye DivergentDivergent---- with movement of RR

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As rays comes out from the eye ConvergentConvergent---- with movement of RR

Observer

As rays comes out from the eye ConvergentConvergent---- with movement of RR

Observer

All the time pupil of pt looks fully illuminated : no mvt

As rays comes out from the eye ConvergentConvergent---- with movement of RR

Observer

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• In high errors the RR appears dim and moves slowly

• And in low errors the RR appears bright and moves rapidly

RR : dimmoves slowly

1

2

Image 2

Image 1

1

RR : brightmoves rapidly

1

2

Image 1

Image 2

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Verification of refraction

Verification of refraction

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Plan mirror

Concave mirror

Changing to a concave or convex mirror

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11 22 33 44

fi l

U + F = V

F

final vergenceInitial vergence

Lens power

F

F

F

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Rapidity of movement of RR :Rapidity of movement of RR :

• Rapidity of mvt of mirror

• Distance between mirror and source of light

• Distance between doctor an patient

• Error of refraction

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animation

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Approaching neutrality

Far point

Far point

Far point

Narrow

Wide

Filled

Finding the cylindrical axis

1. Break 2.Width & brightness

Off axisOff axis On axis

thickdim

thinbright

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Finding the cylindrical axis

3. Skew

Finding the cyln. Axis (straddling)

Cyl. is at 80oCyl. is at 80o

Correct axis

If proper axis …….the RR in the2 positions Should be equal. Here …. Move in the direction of the bright, narrow reflex

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Dynamic Retinoscopy

• The aim is to measure the effectiveness of the accommodation rather than the refractive error itself.

• we need to estimate the power of relative accommodation for a given distance.

Subjective method Objective method

Subjective method to determine Relative accommodation :Relative accommodation :

–– is the amount of accomm that can be exerted while conv. remained fixed (while fixing one point)

Clear image seen with both eyes33 cm

Should be as large as possible = large amount of acc. in reserve.

Should be at least as the –ve part.

So at 3 m.a. the relative acc is 5 D

Add –ve lenses till blurring (e.g. -3) …. +ve relative acc

Add +ve lenses till blurring (e.g. +2)….. –ve relative acc

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objective method to determine

Relative accommodation :Relative accommodation :

Dynamic retinoscopy

The examiner attracted the kid’s attention to the accommodative target and evaluated the retinoscopic reflex in both eyes.

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Focus binocularly

At working distance

Using distance

correction

to fixate an accommodative target at his working distance.

Expected movement of RR is No mvtbut with movement is obtained !

The lag can be explained as an inexactness of focusing.

This is known as the dynamic or objective lag , in normal individuals, usually falls between +0.25D and +1.00D..

If object moved slightly closer to pt No mvtIf + 0.5 or +0.75 are added binocularly No mvt

33 cm

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It can also be measured by moving backward ..

This distance is then measured and the two distances converted into dioptric values to work out the amount of lag present.

When this “With” mvt has been neutralized (the low neutral point)

Accomm.

Shadow is reversed ( high neutral point)

convex lenses are then added binocularly

When “With” mvt has been neutralized (the low neutral pointthe low neutral point)

Accomm.

Shadow is reversed ( high neutral pointhigh neutral point)

“neutral zone “ i.e. -ve relative accomm.i.e. Accomm that can be relaxed relative to convergence

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“neutral zone “

Accomm.

This highest (stongest) convex lens will relax his accomm to max. for that point. It is found it is too strong for the comfort of the patient. It is usually comfort to patient to exert a part of

accommodation.

Correction of presbyopia

• Glasses of distance• Then give convex lens suitable for

pt’s point of near work pt s point of near work. • We must keep 1/3 of his power of

accommodation in reserve (comfortable zone of accommodation)

• 2/3 of accommodation can be used and 1/3 should be kept in reverse to avoid fatigue.g

Comfort zone.