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PupillaEye Exam Lab

Streak retinoscopy: with motion, against motion and neutralization

Updated

Quick answer

Streak retinoscopy measures refractive error objectively by watching the red reflex in the pupil as you sweep a streak of light across it. If the reflex moves in the same direction as the streak ("with motion"), add plus lenses; if it moves the opposite way ("against motion"), add minus lenses. At neutralization the pupil fills with light and shows no motion. The neutralizing lens minus the dioptric value of your working distance — for example 1.50 D at 67 cm — is the refractive error in that meridian.

Open the simulator

Setting up

  • Choose a working distance you can keep constant, usually 67 cm (an arm's length) or 50 cm.
  • Dim the room and ask the patient to look at a distant target past your ear, so accommodation stays relaxed. In children and young hyperopes, cycloplegic drops give the most reliable result.
  • Examine the patient's right eye with your right eye and the left eye with your left eye, staying as close to the patient's line of sight as you can without blocking the target.
  • Set the retinoscope to emit divergent light (the usual plano-mirror setting of the sleeve).

Reading the reflex

What you seeMeaningWhat to do
With motionThe far point is behind you: hyperopia, emmetropia, or myopia smaller than your working-distance dioptresAdd plus
Against motionThe far point lies between you and the patient: myopia greater than your working-distance dioptresAdd minus
Neutral: the pupil fills with light and there is no motionThe far point is at your peepholeRecord the lens

Far from neutral the reflex is dim, slow and narrow. As you approach neutral it becomes brighter, faster and wider. To confirm neutral, lean slightly closer — the reflex should change to with motion — and slightly further back — it should change to against motion.

Working distance and the final prescription

At neutralization, the lens in front of the eye (the gross retinoscopy) puts the patient's far point at your peephole instead of at infinity. To get the distance prescription, subtract the dioptric value of your working distance: net = gross − (1 ÷ working distance in meters).

Working distanceSubtract
50 cm2.00 D
67 cm1.50 D
100 cm1.00 D

Example: at 67 cm the reflex neutralizes with +3.00 D, so the net refraction is +3.00 − 1.50 = +1.50 D. Many examiners instead place a working-distance lens (+1.50 D for 67 cm) in the trial frame first, so the lens that then neutralizes the reflex is the prescription itself.

Astigmatism: finding the principal meridians

  1. Rotate the streak through 180 degrees. In astigmatism the reflex shows a break (the band in the pupil is not in line with the streak outside), differences in width and brightness between meridians, and skew (the reflex moves obliquely).
  2. Rotate the streak until the band in the pupil lines up with it: that orientation marks a principal meridian, and the other is 90 degrees away.
  3. Neutralize one meridian with spheres. Then neutralize the other meridian with more sphere, or with a cylinder whose axis is set parallel to the streak used to measure that meridian.
  4. Combine the two net meridian powers into a prescription.

Worked example at 67 cm: +1.00 D neutralizes the 90° meridian and +3.00 D the 180° meridian. After subtracting 1.50 D, the net powers are −0.50 D along 90° and +1.50 D along 180°. The prescription is −0.50 / +2.00 × 090 in plus-cylinder form, or +1.50 / −2.00 × 180 in minus-cylinder form.

Common mistakes

  • Letting the working distance drift during the examination.
  • Working too far off the visual axis, which creates false astigmatism.
  • Letting the patient look at your light, so accommodation makes a hyperope look less hyperopic.
  • Forgetting to subtract the working distance.
  • Mistaking a very dim reflex with no clear motion for neutral: a large refractive error can look like that too.

Practice it on the virtual patient

  1. Open the streak retinoscopy simulator and set your working distance.
  2. Sweep the streak across the pupil and decide whether you see with or against motion.
  3. Add sphere lenses until the reflex neutralizes.
  4. Add astigmatism, find the two principal meridians, neutralize each one and subtract the working distance to write the prescription.
Open the simulator

Frequently asked questions

With motion or against motion: which needs plus lenses?

With motion needs plus lenses and against motion needs minus lenses. A simple memory aid is "with — add plus; against — add minus".

What working distance should I use for retinoscopy?

Use a distance you can hold constant, most commonly 67 cm (subtract 1.50 D) or 50 cm (subtract 2.00 D). Keeping the distance consistent matters more than the exact value.

What does neutralization look like in retinoscopy?

At neutralization the whole pupil fills with bright red light and there is no visible motion as you sweep the streak. Leaning slightly closer gives with motion, and moving slightly further away gives against motion.

Why use cycloplegic drops for retinoscopy in children?

Children have strong accommodation that can hide hyperopia during retinoscopy. Cycloplegic drops relax accommodation, so the full refractive error, including latent hyperopia, can be measured.