Retinoscopy Flashcards
What is Objective Refraction?
Determining refractive status without input by the patient.
What are the 3 types of Objective Refraction?
- Retinoscopy: Requires patient cooperation and judgement of clinician. Retinoscopy is a form of objective refraction.
- Autorefraction Does not require evaluations of patient or clinician (does require patient cooperation and an operator)
- Photorefraction Photo or video-graph of pupils interpreted by trained clinician or instrument
Retinoscopy
Relies on the following:
The eye is a __________: focusable light can only enter or exit through the pupil.
closed optical system
Retinoscopy
Relies on the following:
The image detection during subjective refraction effectively occurs at ______ (junction of inner/outer segments of photoreceptors).
outer limiting membrane
Retinoscopy
Relies on the following:
Reflection of light from inside the eye produces a ______.
“fundus reflex”
What is the outer limiting membrane?
It is the junction of inner/outer segments of photoreceptors.
Retinoscopy
Relies on the following:
The __________ is also at the outer limiting membrane. Thus, the effective surfaces for reflection and subjective refraction are ________.
effective ocular reflecting surface for visible light
coincident
Why do we do retinoscopy?
- Serves as a starting point for the subjective refraction
- Independent objective confirmation of subjective results
- May be heavily relied on to determine spec Rx for patients unable or unwilling to give reliable subjective responses (examples?)
How do you set up for the retinoscopy test?
Retinoscopy Technique (set-up)
• Phoropter comfortably in front of patient
• Dark room
• Large fixation target at distance
• Examiner positioned arms length away, slightly temporal to eye being scoped:
• one hand manipulates scope
• other hand changes lenses within phoropter
Retinoscopy Technique (procedure) 1) Determine if spherical or astigmatic (is reflex same in all meridians?) What does that mean?
- if same in all meridians (spherical)
* if different (astigmatic), determine the two principal meridians
Retinoscopy Technique (procedure)
2) Neutralize using ____ lenses for “with” motion and ___ for “against” motion (goal is no motion)
• neutralize any meridian if spherical
• neutralize both principal meridians separately if astigmatic (leave “against” in second meridian scoped for minus cylinder).
plus lenses for “with” motion
minus for “against” motion
Retinoscopy Technique (procedure) 3) Complete same procedure in both eyes
4) Add _____ power to compensate for working distance
minus
Tell me about the retinoscopy technique (working distance)?
To compensate for working distance (WD): Add minus sphere = reciprocal of WD
Examples: for 50 cm WD, 1/.5 = 2 (add -2.00 D sphere to both eyes to compensate for WD)
For 67 cm WD, 1/.67 = 1.5 (add -1.50 D sphere to both eyes to compensate for WD)
Summary of Retinoscopy Technique
1) Determine if ________
2) Neutralize using ____ lenses for “with” motion and ____ for “against” motion (goal is no motion)
3) Complete same procedure in both eyes
4) Add minus power to compensate for working distance
- spherical or astigmatic (is reflex same in all meridians?)
• if same in all meridians (spherical)
• if different (astigmatic), determine the two principal meridians - plus
minus
• in any meridian if spherical
• in both principal meridians separately if astigmatic (leave “against” in second meridian scoped for minus cylinder). - minus
Optical Principles
The _____ of retinoscopy (neutrality) occurs when the far point matches with the aperture of the retinoscope.
Endpoint
Optical Principles
How is the endpoint obtained?
1) moving far point to retinoscope (w/ lenses) = static retinoscopy
2) moving retinoscope to far point = dynamic retinoscopy
Optical Principles
What is static retinoscopy?
moving far point to retinoscope (w/ lenses) = static retinoscopy
Optical Principles
What is dynamic retinoscopy?
moving retinoscope to far point = dynamic retinoscopy
Optical Principles
The preferred working distance may vary by practitioner (≈ arms length). You must correct for specific working distance used (add reciprocal of working distance in meters to _____).
endpoint
Fundus Reflex (general principles) (We use these as clues to do retinoscopy.) • \_\_\_\_\_ is red-orange in color, because it is reflected from retina
Reflex
Fundus Reflex (general principles) (We use these as clues to do retinoscopy.) • Procedure to obtain endpoint similar to\_\_\_\_\_\_.
“hand neutralization.”
Fundus Reflex (general principles) (We use these as clues to do retinoscopy.) • Neutrality is a range of uncertainty between perceptible “with” and “against” motions \_\_\_\_\_\_\_.
(bracket midway).
Fundus Reflex (general principles) (We use these as clues to do retinoscopy.) • Six aspects of reflex indicate refractive status:
1) brightness
2) direction of motion
3) speed of motion
4) width
5) definition
6) alignment
Fundus Reflex (details) • Gets \_\_\_\_\_\_ as you approach neutrality (\_\_\_\_\_ when not close or have media opacities, etc.)
brighter
dimmer
Fundus Reflex (details)
• Motion ____ as you approach neutrality (endpoint = no motion). Remember, motion in same direction requires plus lenses to neutralize and motion in opposite direction requires minus lenses to neutralize.
decreases
Fundus Reflex (details)
• Speed _____ as you approach neutrality (yes, that’s correct!)
increases
It. approaches infinity.
Fundus Reflex (details) • Width \_\_\_\_\_\_ as you approach neutrality
narrows
Fundus Reflex (details) • Definition \_\_\_\_\_ as you approach neutrality. It becomes more aligned with streak as you approach neutrality.
increases
It’s easier to see the edges and it is clearer.
Fundus Reflex (abnormal)
• Sometimes the reflex looks funny or “confused.”
• Some portions of reflex may behave different than others
• An example is “scissors” motion (peripheral portions of reflex differ from central portion).
What do we do in these cases?
Pay attention to the reflex in the CENTER of the pupil.
Pay attention to the brackets.
Control of Accommodation
• During ________, accommodation should be relaxed.
This is achieved by “fogging” both eyes prior to determining endpoint.
Question: Doesn’t that blur the target? What about second eye (once first eye neutralized)?
standard “static” retinoscopy
Answer:
Adding too much plus, the eye can’t accommodate.
Control of Accommodation
Make sure patient fixates distant target, not retinoscope light. How can you tell?
Reflex and pupil changes
What are potential problems that could interfere with retinoscopy?
- Examiner too far to the side (excess obliquity of observation)
- Reflections (from cornea and/or lenses)
- Accommodation
What are we hoping to get from doing retinoscopy?
Retinoscopy Results
Should be repeatable within _____ D in each principal meridian, and ____ axis of cylinder.
+/- 0.50
+/- 5°
What are we hoping to get from doing retinoscopy?
Retinoscopy Results
Retinoscopy ≠ subjective refraction
Retinoscopy is objective. The findings require modification during subjective refraction.
Retinoscopy findings and subjective refraction are highly _____.
correlated
What are we hoping to get from doing retinoscopy?
Retinoscopy Results
There is consistent _____ bias of retinoscopy in young patients.
hyperopic
