Welch Allyn 18200 Manuale utente

Streak Retinoscopy

Part Number 18200

La rétinoscopie à strie

No de référence :18200

Strichskiaskop

Teile-Nr. 18200

Retinoscopía de franja

No. de repuesto 18200

Retinoscopia a striscia

N. referenza 18200

English . . . . . . . .1

Français . . . . . .14

Deutsch . . . . . .28

Español . . . . . .42

Italiano . . . . . . .56

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Thank you for purchasing the Welch Allyn No. 18200

3.5v halogen streak retinoscope. This instrument

has been designed to meet the needs of today’s

practitioners and incorporates features not found

on any other retinoscope:

1. External Focusing Sleeve—unique planetary gear

system allows for easy adjustment no matter what size

hand or how instrument is held. Continuous 360°

rotation. Maintains the same plane of focus during

rotation.

2. Improved Light Output—brighter halogen lamp

provides 50 percent more intensity than previous lamps.

The reflex is now crisper and easier to see in all patient’s

eyes. Retinoscopy can be done faster and more accurately.

3. Dust-free Optics—new housings and glass cover on the

front keep the instrument cleaner longer.

4. Crossed Linear Polarizing Filter—dramatically

reduces glare from lenses. Allows retinoscopy to be

performed closer to the axis of the correcting lenses.

5. Fixation Cards—new cards that easily attach increase

the ease with which dynamic retinoscopy is performed.

6. Improved Optics—glare and shadows have been

eliminated for a clearer and more precise view.

7. Interchangeability—By simply changing the lamp,

the streak retinoscope can be converted to a spot

retinoscope.

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1

Introduction

Retinoscopy is a technique for objective refraction of the eye. There

are two basic types of retinoscopy. Static retinoscopy (described in

this booklet) is done with the patient fixating at a distance. Dynamic

retinoscopy is done with the patient fixating at a near target. These

techniques require diligence and expertise that can result in a

precise measurement of the refractive error of an eye.

There are two types of self-illuminated retinoscopes. The streak

retinoscope featured in this booklet is the most widely used

scope today and has largely supplanted the spot retinoscope. In

retinoscopy, a parallel or slightly divergent beam of light is directed

into the patient’s eye. This results in illumination of the retina, and

the reflected light from the retina causes reflexes observed by the

examiner in the patient’s pupil. The refractive status of the eye is

found by using correcting trial lenses to make the far point of the

ametropic eye conjugate to the pupil of the examiner’s eye. When this

is achieved, the movement of the reflex will be neutralized.

The material in the booklet is presented with the assumption that

the reader is familiar with retinoscopy in general. Two excellent

references for retinoscopic technique are:

Corboy, J.M.; The Retinoscopy Book, 3rd Edition, 1989, SLACK Incorporated.

or on videotape: Guyton, D.L.; Retinoscopy: Minus Cylinder Technique or

Retinoscopy: Plus Cylinder Technique, 1986, American Academy of

Ophthalmology—Continuing Ophthalmic Video Education.

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The streak retinoscope is found by most practitioners to be easy to

use, fast, accurate, and especially valuable in determining the axis of

astigmatism.

There are several features of the streak retinoscope that make

determining the refractive state of the eye easy and accurate. These

are:

1. Each meridian can be neutralized separately.

2. All errors can be neutralized using either “with” or “against”

motion or perhaps using both.

3. The axis of astigmatism is apparent.

4. Streak retinoscopy is easy because one watches a band of light

instead of a shadow.

5. Streak retinoscopy may easily be done with undilated pupils.

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Technique

1. The Operation of the Control Sleeve

of the Scope

The operator will note that the width of the

streak varies as the sleeve is raised and

lowered (see Figure 1). When the operating

sleeve is in the lowest position the light rays

emitted are slightly divergent. Here the

instrument acts with a plano mirror effect,

which reflects divergent rays that will never

come to a focus. As the sleeve is raised, the

streak focuses. With the sleeve all the way up,

the retinoscope acts with a concave mirror

effect, where the light rays cross and then

diverge. Because the rays cross, the eye’s

reflex moves in opposite directions with the

concave mirror effect as compared to the

plano mirror effect.

Throughout this booklet, we will use the

plano mirror effect unless specified.

The rotary movement of the control sleeve

mechanism allows the streak to rotate 360°

to ascertain the axis of astigmatism (see

Figure 1).

2. Preliminary Steps

A) Set the sleeve in its lowest position

(plano-mirror effect).

Figure 1

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B) Position yourself 2/3 meter (26") from the patient. This

distance implies a working lens of +1.50D (computed as the

reciprocal of working distance in meters). Working distance

and lens may be varied to suit the practitioner’s needs. (In

this instruction book the 2/3 meter (26") working distance

is assumed. Different working distances can be used, but

remember to adjust for your working distance.)

C) With the refracting equipment in place, direct the patient’s

attention to a fixation spot at 15 feet or more from the eye

and align the streak vertically.

D) Observe the “reflex” which will appear as in Figure 2,

providing no oblique astigmatism is present. If oblique

astigmatism is present, the reflex will appear more like

Figure 3, where the reflex does not appear vertical.

E) Move the vertical streak horizontally across the pupil and

back again and observe whether the reflex moves in the same

direction as the streak or in the opposite direction.

4

Figure 2 Figure 3

No oblique astigmatism Oblique astigmatism

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F) Rotate the control sleeve until the streak is horizontal

and move the streak vertically. The reflex will appear as in

Figures 4 or 5.

G) If the streak and the reflex move in the same direction with

no lens in the refractive apparatus, the refraction is one of

these:

1. Hyperopia;

2. Emmetropia;

3. Myopia of less than 1.50 diopters.

If the reflex moves in the opposite direction, the error is myopia

greater than 1.50 diopters.

3. Determining Refractive Error By Neutralization

Before starting, make sure the eye not being refracted has some

“against” motion using the plano mirror effect. This will blur vision

to prevent accommodation. If “with” or neutral motion is noticed

initially, place about a +1.00 sphere before the eye once neutral

motion is seen.

A) Neutralizing with spheres only:

1. Change sphere in the minus direction until the reflexes in

all axes have “with” motion.

2. Adjust in the plus direction until the reflex fills the pupil

in one meridian and all motion has stopped. This will be

one of the principal meridians if astigmatism is present.

That meridian is then said to be neutralized.

Figure 4 Figure 5

No oblique astigmatism Oblique astigmatism

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3. Test for neutralization by one of these methods:

a) Move the sleeve all the way up (concave mirror

position); the reflex should also appear neutralized;

b) Move closer to the patient and “with” motion should

return; move away and “against” motion should

appear, or

c) Place an extra +0.25 sphere in the apparatus and

“against” motion should appear;

4. Repeat the neutralization in the meridian 90° away.

B) Locating the axis of astigmatism:

Two phenomena help in determining the axis of astigmatism:

break and width. Break is observed when the streak is not

aligned with a principal meridian of the astigmatism (Figures 3

and 5). The streak will be aligned with a principal meridian

when the break effect disappears and the width of the reflex is

narrowest (and it appears its brightest) (Figure 6).

Proceed with neutralization as before—neutralizing one principal

meridian first, then 90° away to neutralize the second principal

meridian (Figures 7 and 8).

6

Figure 6

Figure 7 Figure 8

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4. Interpretation of Results

A) Hyperopia

1. Hyperopia exists when, at the 2/3 meter distance using the

plano mirror effect, “with” motion is neutralized using a

plus lens greater than +1.50 diopters and both meridians

neutralize with the same strength lens.

2. Total hyperopia is estimated by subtracting 1.50 diopters

from the total strength lens used. For example, if it takes a

+2.50 lens to neutralize motion at 2/3 meter, the total

hyperopic error is +1.00 diopter.

B) Myopia

1. Myopia exists under several circumstances.

a) When “with” motion, using the plano mirror effect at 2/3

meter, is neutralized with a plus lens of less than 1.50

diopter strength. (When motion is neutralized with

exactly a 1.50 diopter lens, the eye is emmetropic.)

b) When at 2/3 meter, using the plano mirror effect, no

motion appears at all. In other words, when the motion

is neutralized with no lens in the refracting apparatus.

The myopia is then exactly 1.50 diopters.

c) When the motion is “against” using the plano mirror

effect, and is neutralized with a minus lens.

C) Astigmatism

1. Astigmatism exists when the two principal meridians

neutralize with different strength lenses. It may be present

in many forms.

a) Simple hyperopic;

b) Simple myopic;

c) Compound hyperopic;

d) Compound myopic;

e) In the mixed form

(one meridian hyperopic and the opposite one myopic).

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2. Astigmatism can be measured in one of two ways:

a) Neutralize one principal meridian first. Then add the

appropriate plus or minus cylindrical lens until the

other principal meridian is neutralized.

b) Neutralization may also be done by continuing to add

spherical lenses until the second principal meridian

is neutralized. Then the astigmatic error is equal to

the difference in strength of lenses necessary to

neutralize the two meridians.

5. Special Considerations

A) Axis of astigmatism: Extreme care must be used in setting the

axis of the cylinder. If the correcting cylinder is of the proper

power, a 10° error in axis will produce a new astigmatism

of approximately one third of the strength of the original

astigmatism with its principal meridian at approximately 45°

to those of the original astigmatism. The technique for setting

the axis is referred to as “straddling”. When you have an

approximate correction of the refractive error and wish to

refine the axis setting, the following technique will be helpful.

Move up closer to the eye so that the edges of the reflex can

be seen, and compare the widths of the two reflexes as you

rotate the streak 45° to either side of the correcting cylinder

axis. Recede slowly while doing this. Compare the widths of

the two reflexes. If there is an axis error, the reflex will be

different widths in the two positions. If you are using plus

cylinders, rotate the axis toward the narrow band until the

reflex widths are equal. With minus cylinders, move the axis

away from the narrow band. When the reflex widths are

equal, the proper axis has been determined. It is important

that the spherical and cylindrical strength be checked again

after completion of this maneuver.

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Other Features

This retinoscope was designed with the needs of today’s practitioner

in mind. Listed below are several additional features that will

increase your diagnostic capability.

DYNAMIC RETINOSCOPY—The Welch Allyn 3.5v Halogen

streak retinoscope can be outfitted with magnetic fixation cards

(No. 18250) to help perform dynamic retinoscopy. In dynamic

retinoscopy, the patient is asked to fixate on words, shapes or

another age-appropriate target in the plane of or even on the

retinoscope itself. Dynamic retinoscopy is usually done immediately

after completing static retinoscopy. There are many methods of

dynamic retinoscopy, among these are book retinoscopy, bell

retinoscopy, MEM (Monocular Estimation Method) retinoscopy

and near retinoscopy.

Some uses of Dynamic Retinoscopy:

1. To check for accommodative disorders;

2. To obtain refractive information;

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3. To help decide amplyopic therapy;

4. To determine the adequacy of

cyclopegia.

For more information on Dynamic

Retinoscopy, read the following:

Guyton, D.L., O’Connor, G.M.: Dynamic

Retinoscopy, Current Opinion in

Ophthalmology 1991, 2:78-80.

Locke, L.C., Somers, W.: A Comparison

Study of Dynamic Retinoscopy Techniques.

Optom Vis Sci 1989, 66:540-544.

Mazow, M.L., France, T.D., Finkleman,

S., Frank, J.: Acute Accommodative and

Convergence Insufficiency. Trans Am

Ophthalmol Soc. 1989, 87:158-173.

SPIRALLING—Spiralling is a method for

estimating ametropia without lenses. This

can be helpful in determining the starting

point for lens introduction when working with patients who have a

high unknown ametropia. The Welch Allyn No. 18200 streak

retinoscope is particularly well suited for this technique because the

instrument maintains the same focal plane during streak rotation.

CROSSED LINEAR POLARIZING FILTER—A crossed linear

polarizing filter can be engaged by moving the sliding switch on the

practitioner’s side of the instrument from the down to the up position

(see Figure 9). This filter cuts down on reflections and allows

retinoscopy to be performed closer to the axis of the correcting lens.

SPOT RETINOSCOPY—The Welch Allyn No. 18200 streak

retinoscope can be converted to a spot retinoscope by simply

changing the lamp. In recent years the spot retinoscope has been

largely supplanted by the streak but there are some practitioners who

still favor the spot retinoscope.

Figure 9

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Some arguments presented for using the spot retinoscope are:

1. When working with pediatric patients, it is important to get the

most information in the shortest amount of time. The spot scope,

based on the shape of the reflex, can help detect astigmatism very

quickly. Also significant amounts of myopia and hyperopia can be

determined rapidly.

2. For vision screening a large number of patients, e.g. school

screenings, the spot retinoscope can help provide more

information in a shorter period of time.

3. For judging the fit of hard contact lenses the spot scope can be

helpful in assessing power correction, centration, tear film layer,

etc.; and to check soft lenses for indications of buckling, lens

transparency, and steep or flat corneal correspondence.

To convert the No. 18200 streak retinoscope to a spot

retinoscope, simply insert the No. 08300 lamp (see directions

on page 12). The spot retinoscope is used in the plano mirror

position (sleeve all the way down).

For more information on Spot Retinoscopy, read the following:

Borish, I.M.; Clinical Refraction 3rd Edition, 1970, The Professional

Press Inc. Pg 672.

Cleaning Instructions

Retinoscope—External housings may be cleaned with a mild

detergent and soft cloth. Do not immerse. Windows may be

cleaned with alcohol on a cotton swab or lens paper.

Fixation Cards—May be cleaned with a mild detergent.

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Instructions for

Lamp Replacement

No. 18200 Streak Retinoscope

(Use only Welch Allyn 3.5v Halogen Lamp No. 08200)

No. 18300 Spot Retinoscope

(Use only Welch Allyn 3.5v Halogen Lamp No. 08300)

1. Remove retinoscope from power source.

2. Remove lamp: Lift out with nail file, letter opener or similar

instrument under base flange.

CAUTION: Lamp may be hot and should be allowed to

cool before removal.

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3. Insert new lamp:

08200 lamp—line up pin on lamp with slot between the metal

electrical contact wires. Push lamp into receptacle as far as

it will go.

08300 lamp—push lamp into receptacle as far as it will go.

Lamp should insert easily—do not force. Lamp base contact pin

should be even with metal cutouts in retinoscope base.

4. Replace retinoscope on power source.

The No. 18200 and No. 18300 are essentially the same instrument.

The No. 18200 streak retinoscope can be converted to a spot

retinoscope by simply inserting the 08300 lamp, and vice versa.

Slot

Electrical contact wires

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Merci d’avoir fait l’achat du rétinoscope à strie à

halogène 3,5 V no 18200 de Welch Allyn. Cet instrument

a été conçu pour répondre aux besoins des praticiens

d’aujourd’hui et comprend des fonctions qu’aucun autre

rétinoscope ne peut offrir :

1. Manchon de focalisation externe – ce système exclusif à

engrenage planétaire facilite le réglage, quelles que soient la

taille de la main et la manière dont l’instrument est tenu. Il

permet une rotation continue sur 360° et conserve le même

plan de convergence pendant la rotation.

2. Rendement lumineux accru – la lampe à halogène

améliorée procure 50 % de plus d’intensité lumineuse que

les lampes précédentes. Le réflexe, plus net, est plus facile à

voir dans l’oeil de tous les patients. La rétinoscopie est

effectuée plus rapidement et plus efficacement.

3. Protection des composants optiques contre la

poussière – Le nouveau boîtier muni d’un couvercle en

verre à l’avant garde l’instrument propre plus longtemps.

4. Filtre polarisant à champs linéaires croisés – il réduit

considérablement l’éblouissement causé par les lentilles et

permet d’effectuer la rétinoscopie plus près de l’axe des

lentilles correctrices.

5. Cartes de fixation – de nouvelles cartes à installation

rapide facilitent l’exécution de la rétinoscopie dynamique.

6. Composants optiques améliorés – l’éblouissement et les

ombres ont été éliminés pour assurer une vue plus claire et

plus précise.

7. Interchangeabilité – il suffit de changer la lampe pour

convertir le rétinoscope à strie en rétinoscope à spot.

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Introduction

La rétinoscopie, technique de réfraction objective de l’œil, se divise en deux

types fondamentaux : la rétinoscopie statique (décrite dans cette brochure),

au cours de laquelle le patient fixe une cible à une distance, et la

rétinoscopie dynamique, au cours de laquelle le patient fixe une cible

rapprochée. Ces techniques, qui exigent diligence et compétence, permettent

de mesurer avec précision les erreurs de réfraction de l'œil.

Il existe deux types de rétinoscope à éclairage intégré : le rétinoscope à

strie, dont il est question dans cette brochure, le plus couramment employé

aujourd'hui, et le rétinoscope à spot, largement supplanté par le premier. La

rétinoscopie consiste à diriger un faisceau lumineux parallèle ou légèrement

divergent dans l’œil du patient, dont la rétine est alors éclairée. La lumière

réfléchie par la rétine provoque des réflexes, observés par le praticien dans

l’œil du patient. Pour mesurer l'état de réfraction de l’œil, on utilise des

lentilles correctrices d'essai afin de faire correspondre le punctum remotum

de l’œil amétropique avec la pupille du praticien. Lorsqu’on obtient ce

résultat, le déplacement du réflexe est neutralisé.

L’information que nous présentons dans cette brochure suppose que le

lecteur connaît les principes généraux de la rétinoscopie. Voici deux

excellents ouvrages de référence concernant cette technique :

Corboy, J.M. ; The Retinoscopy Book, 3

e

édition, 1989, SLACK Incorporated

Sur bande vidéo : Guyton, D.I. ; Retinoscopy: Minus Cylinder Technique ou

Retinoscopy : Plus Cylinder Technique, 1986, American Academy of

Ophthalmology – Continuing Ophthalmic Video Education.

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La plupart des praticiens jugent le rétinoscope à strie facile d’emploi, rapide,

précis et particulièrement utile pour déterminer l’axe d’astigmatisme.

Le rétinoscope à strie comporte plusieurs fonctions grâce auxquelles il est

facile de déterminer avec précision l’état de réfraction de l’œil :

1. Chaque méridien peut être neutralisé séparément.

2. Toutes les erreurs peuvent être neutralisées par un déplacement « dans

le même sens », « dans le sens contraire » ou les deux.

3. L’axe d’astigmatisme est visible.

4. La rétinoscopie à strie est facile à effectuer, car le praticien regarde une

bande de lumière au lieu d’une ombre.

5. La rétinoscopie à strie peut facilement s’effectuer lorsque la pupille n’est

pas dilatée.

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Technique

1. Fonctionnement du manchon de

commande du rétinoscope

L’utilisateur notera que la largeur de la strie varie

selon qu’il lève ou qu’il abaisse le manchon (voir

1a figure 1.) Quand le manchon est à sa position

la plus basse, les rayons lumineux émis sont

légèrement divergents. L’instrument agit alors

comme un miroir plan, en reflétant des rayons

divergents qui ne convergeront jamais. A mesure

que l’on relève le manchon, la strie converge.

Lorsque le manchon est complètement relevé, le

rétinoscope agit comme un miroir concave ; les

rayons lumineux se croisent, puis divergent.

Lorsque les rayons se croisent, le réflexe de l’œil

se déplace dans la direction opposée par rapport

à l’effet de miroir plan.

Nous utiliserons dans cette brochure l’effet de

miroir plan, sauf indication contraire.

Le mouvement de rotation du mécanisme du

manchon de commande permet de faire tourner

la strie sur 360° pour déterminer l’axe

d’astigmatisme (voir 1a figure 1).

2. Étapes préliminaires

A) Régler le manchon à sa position la plus

basse (effet de miroir plan).

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Figure 1

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B) Se placer à environ 66 cm (26 po) du patient. Cette distance

requiert une lentille de + 1,50 D (la valeur inverse de la distance

opérationnelle en mètres). La distance opérationnelle et la lentille

peuvent varier selon les besoins du praticien. (Dans cette brochure,

nous supposons que la distance opérationnelle est de 66 cm (26

po). Il est possible d’utiliser différentes distances opérationnelles ;

ne pas oublier, toutefois, d’effectuer les réglages en fonction de cette

valeur.)

C) Le dispositif de réfraction étant en place, demander au patient de

fixer un point situé à 5 m (15 pieds) ou plus de son œil et aligner

la strie verticalement.

D) Observer le « réflexe » qui apparaîtra comme illustré à la figure 2

s’il n’y a pas d’astigmatisme oblique. Sinon, il apparaîtra comme

illustré à la figure 3, c’est-à-dire qu’il ne sera pas vertical.

E) Déplacer la strie verticale de gauche à droite sur la pupille, et

observer si le réflexe se déplace dans la même direction que la strie

ou dans la direction opposée.

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Figure 2 Figure 3

Pas d’astigmatisme oblique Astigmatisme Oblique

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