Retinoscopy

Question 1

Techniques for determining refractive index without input by the patient

Answer 1

Retinoscopy

Autorefraction

Photorefreaction

Question 2

Retinoscopy relies on the following:

Answer 2

The eye is a closed optical system: focusable light can only enter of exit the pupil.

Image detection during subject refraction effectively occurs at outer limiting membrane (junction of inner/outer segments of photoreceptors)

Reflection of light from inside the eye produces a “fundus reflex”

The effective ocular reflecting surface for visible light is also at the outer limiting membrane.

Question 3

Reflection of light from inside the eye produces a:

Answer 3

Fundus reflex

Question 4

Image detection during subjective refraction AND effective ocular reflecting surface for visible light occur at:

I.e. The effective surfaces for reflection and subjective refraction are..

Answer 4

The outer limiting membrane. They are coincident.

Question 5

Why do retinoscopy?

Answer 5

Starting point for subjective refraction

Serves as OBJECTIVE confirmation of SUBJECTIVE results.

Heavily relied on to determine spec Rx for pts unable or unwilling to give reliable responses

Question 6

Setup for Retinoscopy

Answer 6

Phoropter comfortably in front of pt

Dark room

Large fixation target in distance

Examiner positioned arms length away, slightly temporal to eye being scoped:

• one hand manipulates scope
• other can changes lenses within phoropter

Question 7

Procedure for Retinoscopy

Answer 7

1. Determine if spherical or astigmatic (is reflex same in all meridians?)
2. Neutralize using plus lenses for “with” motion and minus for “against” motion (goal is no motion)
3. Complete same procedure in both eyes
4. Add minus power to compensate for working distance

Question 8

When doing retinoscopy, what if reflex is same in all meridians?

Answer 8

Spherical

Question 9

When doing retinoscopy, what is the reflex is different?

Answer 9

Astigmatic.

Determine the two principal meridians

Question 10

When neutralizing the reflex, what do you use for “with” motion?

“Against” motion?

Answer 10

Plus

Minus

Question 11

In retinoscopy, you always want to start with…

Answer 11

AGAINST motion

If you don’t, increase power and work your way back.

Question 12

To compensate for working distance, add _____ sphere

Answer 12

Minus.

Minus = reciprocal of WD

For 67 cm WD, 1/.67 = 1.5

Question 13

Endpoint of retinoscopy occurs when…

Answer 13

Far point coincides with aperture of retinoscope

Neutrality

Question 14

Neutrality is obtained by:

Answer 14

1. Moving far point to retinoscope (w/ lenses) = static retinoscope
2. Moving retinoscope to far point = (dynamic retinoscope)

** MUST correct for specific working distance used (add reciprocal of working distance in meters to end point) **

Question 15

Static retinoscopy

Answer 15

Moving far point to retinoscope (w/ lenses)

Question 16

Dynamic retinoscopy

Answer 16

Moving retinoscope to far point

Question 17

Fundus reflex

Answer 17

Reflex is red-orange in color, because it is reflected from retina

Procedure to obtain endpoint similar to “hand neutralization.”

Neutrality is a range of uncertainty between perceptible “with” and
“against” motions (bracket midway).

Question 18

6 aspects of reflex that indicate refractive status

Answer 18

1. Brightness
2. Direction of motion
3. Speed of motion
4. Width
5. Definition
6. Alignment

Question 19

Fundus reflex becomes __________ as you approach neutrality.

Answer 19

Brighter

Question 20

Motion ____________ as you approach neutrality.

Endpoint = _____ motion

Answer 20

Decreases

No

Question 21

Speed ___________ as you approach neutrality.

Answer 21

Increases.

Hmm, but motion decreases.

Question 22

Width ___________ as you approach neutrality.

Answer 22

Narrows

Question 23

Definition ___________ as you approach neutrality.

Answer 23

Increases

Question 24

Reflex becomes more _________ with streak as you approach neutrality.

Answer 24

Aligned

Question 25

Abnormal fundus reflex

Answer 25

looks funny or confused Portions of reflex may behave different than others An example is "scissors" motion

Question 26

Control of Accommodation

Answer 26

During standard “static” retinoscopy, accommodation should be relaxed. Achieved by “fogging” both eyes prior to determining endpoint. Doesn’t that blur the target? What about second eye (once first eye neutralized? Make sure patient fixates distant target, not retinoscope light. How can you tell?

Question 27

Potential Problems in Retinoscopy

Answer 27

Examiner too far to the side (excess obliquity of observation) Reflections (from cornea and/or lenses) Accommodation

Question 28

Retinoscopy Results

Answer 28

Should be repeatable within +/- .50 D in each principal meridian, and +/- 5° axis of cylinder Retinoscopy findings and subjective refraction are highly correlated. consistent hyperopic bias of retinoscopy in young patients