Introduction to Retinoscopy Vike Vicente, MD Assistant Professor of Clinical Pediatrics and Ophthalmology Georgetown University Hospital

Introduction to Retinoscopy Retinoscopic refraction allows the examiner to objectively determine a patient’s refractive error and to prescribe proper glasses. This is very useful in nonverbal or preverbal patients and patients with inconsistent responses to a subjective refraction. The results may be affected by the patient’s accommodation, and therefore, the patient should be fully cyclopleged (or be cooperative enough to focus on a distant target).

Cycloplegia In our practice we use: < 6 months of age: 1 drop OU of cyclopentolate 0.5%/phenylephrine 2.5% 6 months to 12 years: 1% cyclopentolate > 13 years: 1% tropicamide and 2.5% phenylephrine for 13 years and older. Patients with dark eyes may require two sets of drops 5 minutes apart. It is important to avoid overdosing young patients as they will be more susceptible to anticholinergic effects such as gastroparesis, psychosis, flushing, etc. A larger, dilated pupil will also make it easier for the examiner to see a larger red reflex.

Loose Lenses vs. Phoropter For young patients who cannot sit at the phoropter, trial lenses may be used. A phoropter can be used after the age of 5 years. It is useful if the phoropter has an “R” setting. This places a +1.50 sph lens over the eye and allows the examiner sitting 66 cm to measure the refraction without having to subtract the working distance.

The Retinoscope: Sleeve up or down Retinoscopes are made by different brands, with different sleeve positions. They will have a sleeve up or sleeve down position (see next slides). It is important to use the sleeve position which produces a divergent light. If the sleeve is in the proper position, the streak of light will be divergent and can not be focused on a wall at any distance.

Retinoscope Streak retinoscope bulb has linear filament Move sleeve up or down to produce divergent light Sleeve position varies among instruments

Which sleeve position should you use? Unable to bring in focus no matter where you hold the retinoscope

When would you use the sleeve up, or a thin focused intercept? To better determine the astigmatic axis off the phoropter or trial frame

When would you use the sleeve up, or a thin focused intercept? To better determine the astigmatic axis off the phoropter or trial frame

Retinoscope Sleeve test Put sleeve all the way up Aim streak toward your sleeve Move retinoscope to and fro If streak can focus, put sleeve all the way down

Examiner position: The examiner and retinoscope should be 66 cm away from the patient. The reciprocal of this working distance, 1.5 D, should be subtracted from the final prescription to place the far point of the patient at infinity. If retinoscopy is performed on a patient’s right eye, the examiner should use his or her right eye and hold the retinoscope in their right hand. This will allow the patient to look past the examiner’s right shoulder at a distant target. If the examiner is too far to the right or left of the patient a false plus cylinder error will be induced at 180 degrees.

As the rectangular light intercept is swept across the pupil, it will create a red reflex that moves or fills the pupil (end point of refraction). The rectangle’s long axis should be parallel with the direction in which it is being swept. The light rectangle should be vertical if it is being swept left to right across the 90 degree axis. If the patient’s far point is behind the examiner (hyperopia), the red reflex will move in the same direction as at the light intercept, this is called “with motion.” Plus lenses should be added to converge the red reflex light and bring the far point onto the examiner until the “with motion” is neutralized and the pupil fills in. If the patient’s far point is between the patient and the examiner (myopia) the red reflex will move in the opposite direction as the light intercept and is called “against motion”. Minus lenses should be placed until the motion is neurtralized and the light is diverged away from the patient, onto the retinoscope. If the patient has astigmatism a different red reflex motion will be observed in different axes. If you are working in plus cylinder form, neutralize the most minus or against motion first, then add sphere or cylinder power at the axis 90 degrees away.

With vs. Against movement Intercept Pupil Peephole Far point At neutralization

With vs. against movement Intercept Pupil Peephole Far point “With” movement

With vs. against movement Intercept Pupil Peephole Far point “Against” movement

Remember… An emmetropic child retinoscoped from the side will show against-the-rule astigmatism Horizontal displacement from the visual axis Plus axis of correction at 180 degrees Correct, patient: plano Incorrect patient: -0.50 +1.00 x 180

Plain, sphere

With motion…. Add plus

Against motion…. Add minus

Fills in… just right

Example # 1

With motion…. Add plus

+5.00 Add minus Oops too much plus, Now against motion…

+3.00 Final Rx? +1.50 sph Fills in… just right

Example # 2

Against motion…. Add minus

-5.00 Oops too much minus With motion…. Add plus

-3.00 Final Rx? -4.50 sph Fills in… just right

With Astigmatism Example #1

With motion at 90 Against motion at 180… 1st neutralize the against motion Add some minus

-3.00 180 is neutralized

-3.00 Now neutralize 90 With motion… Add plus

+1.00 Final Rx? -4.50 +4.00 X 90 Fills in… just right

-3.00 +4.00 Or you could also do it this way -4.50 +4.00 X 90

With Astigmatism Example #2

1st neutralize the against motion Add some minus With motion at 90 Against motion at an oblique angle

-3.00 OK oblique Against motion is neutralized

-3.00 Now neutralize Oblique with motion

-3.00 +4.00 Final Rx? -4.50 +4.00 X 70

More examples

Scissors Keratoconus Occurs when one part of the lens or cornea is more myopic

Posterior Lenticonus?

PSC?

Way off lens power Cataract Dull reflex DDx?

What is going on? Changing direction… The patient is still accommodating! Miosis This is useful for dynamic retinoscopy Can a young hyperope accommodate to a near point? …

Always do what the central area tells you. What is causing the different zones? Does this patient see better at night or during the day?

Spherical Aberration Produces bulls-eye retinoscopic reflex Especially in young children Peripheral portions of pupil myopic compared with central portion at neutralization (“With” movement centrally, “against” peripherally) Concentrate on central part of reflex