This is a medical instrument that is used to determine the refractive errors and also the axis of astigmatism of fundus.
This test can be done quickly, easily, reliably, accurately and requires minimal cooperation from the patient.
The two types of retinoscopes are:
- Streak retinoscopes which have a light source which produces a line or streak of light. This streak of light can be changed by moving the slide knob or sleeve.
2. Spot retinoscopes which have a light source that produces a spot of light.
There is a basic principle of retinoscopy which is the Foucault test. This test has a knife edge placed on the principal axis of an optical system (S) which intercepts a bundle of rays coming out of (S). Depending on the position of the knife edge, various distributions of light and shadow can be observed on the anterior surface of (S).
