Retinoscopy Flashcards
Objective refraction
Determining refractive status without input by the patient
What are some forms of objective refraction
- retinoscopy
- autorefraction
- photorefraction
What does retinscopy rely on
- eye is in a closed optical system (1 way in, 1 way out)
- image detection occurs at outer limiting membrane
- fundus reflex
- reflecting surface for visible light is also at the outer limiting membrane
What gives us the objective refraction in retinoscopy
- starting point for subjective refraction
- independent objective confirmation of subjective results
- good for patients unable or unwilling to give reliable subjective responses
Against motion in retinoscopy
Add minus
With motion in retinoscopy
Add plus
Retinoscopy set up
- phoropter comfortably in front of patient
- dark room
- large fixation target at distance
- arms length away, slightly temporal to eye being scoped
Retinoscopy technique
- Determine if spherical or astigmatic (reflex same in all meridians)
- Neutralize using plus for with, minute for against
- Do both eyes
- Add minus power to compensate for working distance
If the reflex is the same in all meridians
Its spherical
If the reflex is different in different meridians
Astigmatic, determine the two principal meridians
How to neutralize astigmatism in retinoscopy
Neutralize both principal meridians separately, leave “against” in second meridian scoped for minus cylinder
How do you compensate for working distance in retinoscopy
Add minus sphere (reciprocal of WD)
1/(WD in m)
endpoint of retinoscopy
Occurs when far point coincides with aperture of retinoscope
How to obtain far point of retinoscopy
- Moving far potion to retinoscope with lenses (static)
2. Moving retinoscope to far point (dynamic)
Static retinoscopy
Moving far point to retinoscope using lenses
-what we normally use
Dynamic retinoscopy
Moving retinoscope to far point
-special circumstances, kids who wont keep focus
Is everyone’s working distance the same?
No, varies from person to person, usually the arm length
Fundus reflex color and reason
Red- organs because it is reflected from retina
What is the procedure to obtain endpoint similar to?
Hand neutralization
Neutrality
A range of uncertainty between perceptible “with” and “against” motions (bracket midway)
Aspects of reflex indicate refractive status
- Brightness
- Direction of motion
- Speed of motion
- Width
- Definition
- Alignment
When does the fundus reflex get brighter?
As you approach neutrality
When doe the fundus reflex get dimmer?
When not close or when you have media opacities (cataract)
When does the motion decrease?
As you approach neutrality (endpoint=no motion)
When does speed of reflex increase?
As you approach neutrality
What happens to the width when you approach neutrality?
Narrows
When does definition increase in retinoscopy?
As you approach neutrality
When does it become more aligned with streak in retinoscopy?
As you approach neutrality
What causes abnormal fundus reflex?
- higher order aberrations
- some portions of reflex may behave different than others
- scissors (peripheral portions of reflex differ from central portion)
Accommodation in static retinoscopy
Should be relaxed
How can you tell if someone is accommodating too much?
Look at reflex in center of pupil, pupils will also constrict
Fogging
Adding more plus to both eyes prior to determine end point
Where should patient fixate?
On distant target, not retinoscope light
Potential problems
- Examiner too far to side
- reflections
- accommodation
Retinoscopy results
Should be repeatable within +/- .50D in each principal meridian and +/- 5 degrees axis of cylinder
Is retinoscopy the same as a subjective refraction?
No
Is retinoscopy the same thing as a the E.G. Rx?
No, wont necessarily use the same numbers, probably not going to write RX with this
Is retinoscopy subjective or objective?
Objective
What do retinoscopy findings require?
Modification during subjective refraction
Retinoscopy findings and subjective findings
Highly correlated
What retinoscopy in young patients
Consistent hyperopic bias
