Retinoscopy: Objective Refraction
Ophthalmology High-Yield: Clinical Skills & Optics
1. Principles
Retinoscopy is an objective method to determine the refractive state of the eye by observing the movement of light reflected from the fundus (the red reflex).
2. Reflex Movement Interpretation
| Movement | Refractive State |
|---|---|
| With Movement | Hypermetropia (or low myopia < working distance). |
| Against Movement | Myopia (greater than the working distance). |
| Neutralization | The far point of the eye is at the examiner’s eye. |
3. High-Yield Pearls
- Working Distance: Usually 66 cm (1.5 D) or 1 meter (1.0 D). The “working distance lens” must be subtracted from the final gross power to obtain the net refraction.
- Scissor Reflex: Observed in cases of keratoconus or irregular astigmatism, where the reflex moves in two directions from the center.
- Cycloplegic Refraction: Mandatory for accurate retinoscopy in children and those with accommodative esotropia to eliminate the influence of accommodation.
- Clinical Tip: If the reflex is extremely dull, it may indicate high refractive errors, significant media opacities (e.g., cataract), or advanced macular disease.