Clinical Skills Retionscopy

Retinoscopy

objective measurement of the refractive state

starting point for subjective refraction

Why is retinoscopy used

useful for infants, illiterates, nonverbal patient, uncooperative patient

retro illumination can detect pathology

The retinoscope is an optical instrument made from an

illumination system and an obesrvation system

illumination system

The light on the patient's face moves in the _____ direction as that of the examiner moving

same

the light in the patient's pupil moves _______ direction as the light on the face

the same or opposite

depending on the patient's refractive error!

examiner needs to see the pupil image

clearly!

plane mirror

apparent light source behind peephole

(light coming from examiner)

concave mirror

displacement of the light source to in front of the plan of the mirror (crosses over)

(light coming from in between patient and examiner)

plane mirror illumination on the face ____

matches light on the retina

sleeve in DOWN position

concave mirror illumination on the face and on the retina ___

will move in the direction opposite to that of the mirror

SLEEVE UP

The orientation of the streak is always ------- to the meridian of the eye being scoped

at right angles

named for the movement of the beam

streaking =

scoping

Forms of retinoscopy

Static

Dynamic

Static retinoscopy

refractive state while patient fixates on distant object (relaxed accommodation)

6m/20ft/optical infinity

Dynamic Retinoscopy

active accommodation

fixates in near

refractive state while patient fixates at object in the plane of the retinoscope (near targets)

types of dynamic retinoscopy

sheard's method

tait's method

Nott's method

Bell retinoscopy

Monocular estimation method (MEM)

mohindra near retinoscopy

in optics we talk about the ____ while in CS we talk about the_____

error

correction

emmetropia (CS)

parallel light comes to a single point focus on the retina

plano sphere

Simple myopia (CS)

parallel light comes to a single point focus in front of the retina

(-2.25 sphere)

simple hyperopia (CS)

parallel light comes to a single point ficus behind the retina

(+1.75 sph)

observation of the reflex or

motion

With motion

when light is in the right side of the face/eye the reflex is seen in right side of pupil

when light is in left side of face/eye reflex seen in left side of pupil

Against motion

when light is in right side of the face reflex seen in left side of pupil

when light is in left side of the face/eye reflex seen in right side of pupil

Neutral

pupil is illuminates only when the spot on the retina is on the optic axis of the eye

flashing or blinking

no motion

clinical definition of neutral

reflex seen within the pupil of the patient when the peephole of the retinoscope is conjugate to the patient's retina

how can we neutralize motion with retinoscopy

with changing distances

with changing lenses

Changing distances only works with ____ prescriptions

MYOPIC

Far point

Myopic patients have a place at some point in front of optical infinity where the peephole of the retinoscopy is conjugate with the retina (the patients far point)

an objective puntum remotum

If you see against motion

move forward

Any myope can be scoped by finding the distance of the retinoscope peephole for neutral motion - convert the distance to find power

In myopia the far point is

finite distance in front of the eye

In emmetropia the far point is

optical infinity

in hyperioia the fair point is

behind the eye

For emmetroes it is inonveinent to scope at infinity so we

use working distance lenses

for hyperopes, because the far point is behind the eye, we must use

convex lenses

CHANGING LENSES

for all rx

if you see neutral

no lenses are needed

if you see with

need to add plus lenses to have the reflex focus faster onto the retina

(hyperopes)

if you see against

need to add minus lenses to have the reflex be pushed back to the retina

(myopes)

if we perform retinoscopy at optical infinty

images in front of the retina - against motion

images on the retina - neutral

images behind the retina - with

BUT we perform retinoscopy at arms length!

Light from infinity enters the eye as

parallel rays

Light from shorter distances enters light as

divergent rays

we must make them parallel by adding converging lenses (plus lenses/convex)- working distance lenses !

50 cm

+2.00 D

57 cm

1.75

67 cm

1.50

Gross lenses

Rx needed to see neutral at arms length

Net lenses

Rx given to the patient

Neutralize "with" motion

add PLUS in 0.25 or 0.50 D steps

Neutralize against motion

add MINUS lenses

Gross lens power =

WD lens power + net lens power

Net lens power =

Gross - WD

Verifying the Rx

speed of motion

brightness of reflex

mirror position

speed of motion

the pupil reflex will be slower and narrower the further away from neutral you are

brightness of reflex

Peephole is the ------ of the optical system

field stop

When the patient's retina is ----- with the peephole, the illuminated area of the retina is usually larger that the observed area

not conjugate

In high myopia or hyperopia - the reflex seen is ------- and ----than the diameter of the pupil

dull (out of focus)

larger

(difficult to judge speed of movement or which direction the movement is)

As approaching neutral the reflex appears

brighter

Plane mirror (sleeve down)

Myopia - against

Emmetropia - neutral

Hyperopia - with

Concave Mirror (sleeve up)

Myopia - with motion

Emmetropia - neutral

Hyperopia - against

Types of prescriptions

Spherical

Astigmatic - majority of population

WTR astigmatism

most corneal power in vertical

most plus refracting power at 90th

correct with minus cylinder x190

Against the Rule astigmatism

greatest power in horizontal

most plus refracting power @ 180

correct with minus cylinder x 90

Oblique astigmatism

31-59 degrees

121-149 degrees

Majority of population have ___ astigmatism

WTR

scoping parallel to 90th first

scoping parallel to 180th second

interval of sturm

The distance between the two line images

circle of least confusion

located at dioptric mean of two focal lines

Regular Astigmatism

meridians are 90 degrees apart

See slides and draw images of astigmatics

Astigmatic Retinoscopy

neutralize first meridian with sphere (affects all meridians)

second meridian must be AGAINST (so we can do minus cyl)

neutralize second meridian with minus cylinder - only affect one meridian

8 types of refractive diagnosis

Emmetropia

Simple Myopia

Simple Hyperopia

Compound Hyperopic astigmatism

Simple hyperopic astigmatism

Simple myopic astigmatism

Compound myopic astigmatism

Mixed astigmatism

Compound Hyperopic Astigmatism

both focal lines are located behind retina

both meridians will be "with" motion

neutralize the slowest with first (most plus power)

a plus sphere lens moves both meridians forward

the second meridian will be against

Must have one neutral and second myopic for minus cylinder

Simple Hyperopic Astigmatism (SHA)

one is on the retina (neutral) and one is behind the retina (with)

Neutralize the "with" first (most + power)

Plus sphere lens will move both meridians forward

the second meridian will be against

Must have one neutral and second myopic for minus cylinder

Simple Myopic Astigmatism (SMA)

one on the retina (neutral) and one in front of the retina (against)

first meridian is already neutralized

second meridian will be against

NO sphere needed

Must have one neutral and second myopic for minus cylinder

Compound Myopic Astigmatism (CMA)

Both will be in front of the retina (against)

neutralize the fastest brightest against (closest to neutral)

a minus sphere lens moves both meridians back

second meridian will be against

Must have one neutral and second myopic for minus cylinder

Mixed Astigmatism (MA)

one behind the retina (with) and one will in front of the retina (against)

neutralize the with motion median first (most plus)

use a plus sphere to move both meridians forward

second meridian will be more against

Must have one neutral and second myopic for minus cylinder

Retinoscopy rules

1. Use sphere power first to neutralize the most plus meridian

2. Minus Cylinder - neutral in one meridian and against in the other

3. Use MINUS CYLINDER with axis of correcting cylinder matching orientation with the against motion

4. Add enough cyl power to get neutral motion

5. Both meridians will now be neutral (gross)

6. Remove working distance (-WD from sph)

7. Record NET lenses

Minus Cylinder

begin with the meridian with the most "with" motion (thinner reflex) --> change the sphere only til neutral

second meridian must be against to neutralix with minus clinder (minus)

Down on the wheel adds

PLUS

neutralize WITH motion

UP on the wheel adds

MINUS

neutralizes against

Ways to identify meridians

Looking at streak

1. Break in Streak

2. thickness if streak (thinner when aligned)

Moving streak

3. Skew in movement

Concentrate on the center --- of pupil

3 mm

PROCEDURE and PARTS OF PHOROPTER

VERIFY

Bracket with lenses

go past neutral

add plus lenses to get Against

add minus to get with

then reduce back to netral

Bracket with distance

move in until see with motion

move back until see against motion

Verify with Mirror postion

stays neutral in either position!

Straddling axis - Look

place streak at 45d degree to either side of axis

move in until see "with" motion

Observe reflex - NO movement

should eb equal on both side

if reflex is brighter on either side you have indorrect axis - 5 degree steps

Straddling axis - move

place at 45 degrees to either side of axis

move the streak - motion should be the same on both sides (both with or both against)

if not - move toward the side with against 5 degree steps

Sources of error

1. Active accommodation

2. incorrect working distance - wrong net lenses

3. off-axis scoping - induced astigmatism

4. failure to locate primary meridians - scissors motion seen

5. spherical aberration - refractive surgery/disease

6. Very small pupils - hard to see reflex/ cataracts

7. eye turn - hard to get good fixation

8. very high ametropia - difficult to tell mtion

The lens combination that allows us to see Neutral in static retinoscopy is called the ___________ lenses

GROSS

The lens combination that we would prescribe to a patient would be called the ____________ lenses.

NET

SEE SLIDES FOR PRACTICE