PC - Retinoscopy - Week 2

Question 1

How do retinoscopes work?

Answer 1

Emits light towards the pupil, allowing the operator to view the red reflection of the retina.

Question 2

Describe the basics of how a retinoscope is used.

Answer 2

Practitioner sweeps the beam across the eye. The movement of the red refex relative to the direction of the sweep indicates the type of refractive error, and the speed indicates magnitude.

Question 3

What is the objective of retinoscopy?

Answer 3

The eye should illuminate with the red reflex all at once.

Done by finding the far point of the eye, and adjusting it with lens.

Question 4

Define a with movement in retinoscopy. What does this kind of movement indicate?

Answer 4

The red reflex in the pupil is in the same direction as the direction of sweep used by the practitioner.
Indicates hyperopia.

Question 5

Define an against movement in retinoscopy. What does this kind of movement indicate?

Answer 5

The red reflex in the pupil is in the opposite direction as the direction of sweep used by the practitioner.
Indicates myopia.

Question 6

Define a neutral movement in retinoscopy. What does this kind of movement indicate?

Answer 6

The red reflex has no direction as the eye illuminates at once.
Indicates emmetropia.

Question 7

Define static retinoscopy and dynamic retinoscopy.

Answer 7

Static - used to quantify amount of ametropia objectively

Dynamic - used to objectively investigate accommodative state of the eye - near vision

Question 8

Describe the basic clinical procedure for static retinoscopy.

Answer 8

Align the phoropter or trial frame, with both patients eyes open.
Have them focus at distance
Face the patient, with a working distance of 50-67cm
View their RE with your RE, their LE with your LE
Do not obscure their distance target

Question 9

How is retinoscopy performed if the patient has astigmatism?

Answer 9

The beam must be aligned to their meridian axis.

Instrument must always be moves perpendicular to the streak. If horizontal, beam should be moved up/down.

Question 10

In an astigmatic patient, when meridia is found, how can the second one be determined?

Answer 10

Rotate the beam to 90 degrees of the first meridia.

If it isnt present, the patient may be spherical.

Question 11

In an astigmatic patient with 2 meridia, which should be neutralised first?

Answer 11

Most hyperopic/least myopic first.

Question 12

What happens to the movement speed and brightness as you approach neutralisation?

Answer 12

Movement will quicken, and brightness will increase.

At neutralisation, movement is undetectable, and and brightness is highest.

Question 13

Describe how neutralisation is achieved.

Answer 13

Continue adding powers until the reversal of movement. At that point, powers can be removed by a step or so.

Question 14

Once a meridian is neutralised, what lens is used for the second meridian? What should the axis coincide with?

Answer 14

Minus cylindrical lens, with axis coinciding with the same direction as the streak/beam orientation, perpendicular to the sweep direction.

Question 15

Whena cylinder is added, would the orientation of the reflex change?

Answer 15

No, if it does, it indicates obliquely crosses cylinder.

Question 16

How can the end points be confirmed?

Answer 16

Move closer - expect with movement

Move away - expect against movement

Question 17

Working distance is typically 50 or 67cm. What lens are needed to account for this?

Answer 17

50cm - +2.00D

67cm - +1.50D

Question 18

What kind of lens is needed for a with movement? What about against movement?

Answer 18

With - plus lens

Against - negative lens

Question 19

Is the red reflex typically very bright or dim?

Answer 19

Very bright at neutrality.
Is dim in high ametropes (both kinds)
May also be dim due to media opacities

Question 20

What is the movement speed of red reflex like at high dioptres?

Answer 20

At 3 dioptres, speed is very slow and can be difficult to tell apart with or against movement.

Question 21

What happens to the width of the red reflex at high dioptres, and as you approach neutrality?

Answer 21

Is very wide (pupil diameter) at high dioptres. Becomes smaller as neutrality is approached, but enlarges once again at neutrality.

Question 22

Describe how a given meridia is neutralised.

Answer 22

The streak/beam is orientated perpendicular to the meridia.
It is swept parallel to the meridia
ie. Vertical meridia - horizontal beam, swept vertically along the meridia

Question 23

Describe how an undetectable initial reflex can occur.

Answer 23

As ametropia increases, the speed of reflex decreases, mimicking neutralisation.
The dullness will indicate it is not at neutrality.

Question 24

Name 12 potential problems that can occur during retinoscopy.

Answer 24

Undetectable initial reflex
Undetected cylinder
Small pupils and media opacities
Failure to allow for working distance lens
Split reflex
Scissors reflex
Excessive reflections
Incorrect working distance
Viewing off visual axis
Poor accommodative control
Failure to locate principle meridian
Failure to obtain reversal (2nd meridian)

Question 25

What causes the split reflex, and how can it be mitigated?

Answer 25

Occurs with cyclopegia, due to spherical abberation.

Concentrate on the centre of the beam

Question 26

What causes the scissors reflex?

Answer 26

Irregular cornea, like keratoconus