Retinoscopy is the cornerstone objective refraction technique in optometric and ophthalmic practice. By projecting a streak or spot of light into the eye and observing how the reflex moves through the pupil, a trained examiner can determine refractive error without any verbal feedback from the patient. This makes retinoscopy invaluable for infants, nonverbal patients, malingerers, and as a starting point for subjective refraction. ABO-NCLE, IJCAHPO COA and COT examinations, and AAO board certification all expect a working command of the procedure.
Concept Overview
Retinoscopy works on the principle of conjugate foci. Light from the retinoscope enters the patient's eye, reflects off the retina, and exits as a divergent beam that the examiner observes through the peephole. By moving the streak across the pupil and adding lenses in front of the eye, the examiner shifts the patient's far point until it coincides with the examiner's pupil. At that moment the reflex fills the pupil and stops moving, indicating neutralization.
The Reflex and What It Tells You
- With motion: the reflex inside the pupil moves in the same direction as the streak. Indicates the patient's far point is behind the examiner. Add plus power.
- Against motion: the reflex moves opposite to the streak. The far point is between the patient and the examiner. Add minus power.
- Neutrality: the reflex fills the pupil and there is no apparent movement. The far point is at the examiner's eye.
Brightness, speed, and width of the reflex give clues to how far you are from neutrality. A dim, slow, narrow reflex is far from neutral. A bright, fast, wide reflex is close. With high refractive errors a scissors reflex (two halves moving in opposite directions) suggests irregular astigmatism or keratoconus.
How It's Performed
Standard static retinoscopy is performed with the patient fixating a distant target (usually 20 feet or 6 meters away) while the examiner sits at a fixed working distance, most commonly 67 cm (about 26 inches) which corresponds to +1.50 D of working-distance compensation. ABO-NCLE materials and most optometric programs teach the 67 cm distance, while some clinicians prefer 50 cm (+2.00 D). The choice must remain consistent throughout the exam.
- Dim the room. A dilated or naturally large pupil produces a brighter, easier-to-read reflex.
- Have the patient fixate the distant target. Encourage them to look around your ear or shoulder so your head does not block fixation. This relaxes accommodation, which is essential because retinoscopy at distance assumes the eye is relaxed.
- Position the retinoscope at your dominant eye and align with the patient's right eye first, then left. Do not block the fellow eye unless performing monocular cycloplegic work.
- Sweep the streak horizontally across the pupil and observe the reflex. Then sweep vertically. Note motion direction and any meridional difference.
- Add lenses from the trial frame or phoropter. Use plus to neutralize with-motion, minus to neutralize against-motion. Approach neutrality gradually.
- Find the two principal meridians if astigmatism is present. Rotate the streak until it aligns with the reflex inside the pupil with no break (the streak and reflex are parallel). Neutralize one meridian, then rotate 90 degrees and neutralize the other.
- Subtract working distance from the gross retinoscopy finding. With a 67 cm distance subtract 1.50 D from the spherical component to get the net refractive error.
Identifying the Cylinder Axis
Three signs help locate the cylinder axis: the break (the reflex appears displaced from the streak when the streak is off-axis), the thickness (the reflex looks narrower when the streak is on-axis), and the brightness (the reflex is brightest when the streak aligns with the principal meridian). Use any of these cues to refine axis before neutralizing each meridian.
Equipment
The streak retinoscope (Copeland or Welch Allyn pattern) is the workhorse instrument. It contains a bulb, a condensing lens, a sleeve that controls vergence, and a mirror with a peephole. Sleeve position changes the source vergence:
- Sleeve down (plane mirror effect): divergent light leaves the instrument. Most clinicians work in this position. With motion means add plus.
- Sleeve up (concave mirror effect): convergent light leaves the instrument. Motion direction reverses. Less commonly used in routine practice.
You also need a working refraction setup: a phoropter or trial frame with a full lens set, a distance fixation target, and a way to dim the room. For pediatric and nonverbal work, near retinoscopy with loose lens bars, Mohindra technique (monocular near retinoscopy at 50 cm in a dark room with the fixation light of the retinoscope itself), or cycloplegic retinoscopy after instillation of a cycloplegic agent are standard variants.
Spot vs Streak Retinoscopes
Spot retinoscopes project a circular light source and were once standard. The streak retinoscope, introduced by Copeland in the 1920s, made cylinder identification much faster because the linear streak is easier to align with a meridian. Modern training emphasizes the streak instrument. ABO-NCLE candidates should know both exist but expect questions about streak technique.
Interpretation
Gross retinoscopy is what is in the trial frame at neutralization. Net retinoscopy is gross minus working distance. Always document both. A gross of +2.50 -1.00 x 180 at a 67 cm working distance becomes a net of +1.00 -1.00 x 180. The cylinder power and axis do not change; only the spherical component is adjusted.
Common Findings and What They Mean
- Bright, fast, full reflex from the start: low refractive error near plano. Small lens additions will reach neutrality.
- Dull, slow, narrow reflex: high refractive error. Use larger lens steps to approach neutral, then refine.
- Scissors reflex: two halves of the reflex move toward and away from each other. Suggests irregular astigmatism, keratoconus, early cataract, or significant spherical aberration.
- Dark spot or shadow in the reflex: media opacity, lens vacuoles, or vitreous floaters can produce focal disruptions.
- No reflex obtainable: dense cataract, vitreous hemorrhage, retinal detachment, or extremely high refractive error beyond available lens range.
Patient Communication
Retinoscopy is brief, painless, and silent on the patient's part, but a few cues help cooperation. Tell the patient you will be shining a light in their eye and that they will see a moving streak. Ask them to keep both eyes open and to look at the letter, picture, or red dot on the far wall. If they keep glancing at your light, redirect them to the distant target and remind them that looking at the bright light will blur the result.
For pediatric patients use a video, a small toy taped to the wall, or a parent's voice as a fixation target. With infants near retinoscopy or Mohindra technique replaces distance fixation. Always explain to a parent what you are doing so they can help keep the child engaged.
Accommodative Pitfalls
Active accommodation will cause myopic shifts and unstable end points. If the reflex keeps changing as you neutralize, the patient is fogging in and out of accommodation. Re-instruct them to look at the distance target, fog the fellow eye with extra plus, or, in pediatric work, instill a cycloplegic agent and refract once cycloplegia is complete. The AAO recommends cyclopentolate 1% for most pediatric retinoscopy, with atropine reserved for high accommodative cases.
Exam Tips
ABO-NCLE, IJCAHPO COA and COT, and paraoptometric (CPO/CPOA) examinations all test retinoscopy concepts. High-yield points to memorize:
- Working distance compensation: 67 cm = 1.50 D, 50 cm = 2.00 D, 100 cm = 1.00 D. The reciprocal of the working distance in meters equals the diopters to subtract.
- With motion always means add plus. Against motion always means add minus. This holds in plane-mirror (sleeve down) position.
- Neutrality is when the reflex fills the pupil and shows no movement. At neutrality the patient's far point is at your peephole.
- The cylinder axis is found before cylinder power. Use break, thickness, and brightness signs.
- Streak and reflex parallel means you are on-axis. A break means you are off-axis and need to rotate the streak.
- Static retinoscopy assumes accommodation is relaxed. Anything that triggers accommodation invalidates the result.
- Cycloplegic retinoscopy is the gold standard for pediatric and high-hyperope refraction. Subtract working distance after cycloplegia just as in routine static work.
- Net refraction = gross refraction minus working distance, applied to the spherical component only.
- Scissors reflex is a red flag for keratoconus or other irregular astigmatism. Refer for topography.
Retinoscopy is a skill that improves with reps. Practice on cooperative adults first, then progress to pediatric and special-population technique under supervision. On exams, expect questions that test working-distance math, motion direction, and the meaning of common reflex artifacts. ABO-NCLE, IJCAHPO, and AAO published exam outlines all list retinoscopy as a core competency for entry-level eye care professionals.