Retinoscopy

 

🔍 What is Retinoscopy?

Retinoscopy is a diagnostic procedure used to estimate the refractive status of the eye by observing the reflected light (reflex) from the retina while moving a light beam across the pupil.

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🔧 Equipment Used

• Retinoscope: A handheld instrument that shines a beam of light into the eye

• Trial lenses / Phoropter: To neutralize the reflex and determine the refractive power

• Lens rack or trial frame: For manual lens insertion during testing

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🧪 How Retinoscopy Works

1. The examiner shines light into the patient's eye using a retinoscope.

2. The light reflects off the retina and comes back out through the pupil.

3. The examiner moves the light beam horizontally and vertically.

4. The movement of the retinal reflex (the light seen in the pupil) is analyzed.

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🧠 Types of Retinoscopy

1️⃣ Static Retinoscopy

• Performed when the patient is focusing on a distant target

• Most common for measuring distance refractive error

2️⃣ Dynamic Retinoscopy

• Patient focuses on a near target

• Used to assess accommodative function, especially in kids

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👁️‍🗨️ Interpreting the Reflex

Reflex Movement	Indicates	Correction Needed
"With" movement	Light reflex moves same direction as retinoscope	Hyperopia or low myopia
"Against" movement	Reflex moves opposite direction	Myopia
No movement (neutral)	Correct lens has been reached	None further

The goal is to neutralize the reflex by adding lenses — when there’s no movement, the refractive error has been corrected.

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🧮 Important Concept: Working Distance

• The examiner typically performs retinoscopy at 50 cm or 66 cm

• So a "working distance lens" (e.g., +2.00 D for 50 cm) must be subtracted from the final result to get the accurate prescription

Example:
If reflex is neutralized with +3.00 D at 50 cm
→ Actual correction = +3.00 – 2.00 = +1.00 D

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🧾 Advantages of Retinoscopy

• Objective (no patient feedback needed)

• Ideal for:

  • Children

  • Non-verbal or uncooperative patients

  • Suspected malingering

• Can detect media opacities, poor fixation, or accommodative problems

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⚠️ Clinical Pearls

• Cycloplegic retinoscopy is used in children to paralyze accommodation, revealing latent hyperopia

• Scissor reflex or irregular movement may suggest astigmatism

• Can also give clues about ocular media clarity (e.g., cataract, corneal scar)

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🎯 Summary

Aspect	Detail
Purpose	Measure refractive error
Instrument	Retinoscope
Reflex Types	"With", "Against", Neutral
Static vs Dynamic	Distance focus vs Near focus
Used in	Kids, non-verbal patients, objective exams
Final result	Adjust for working distance