Retinoscope: Principle, types, Technique, and Clinical Applications

This presentation provides a comprehensive overview of the retinoscope, an essential diagnostic instrument in optometry and ophthalmology. It covers the principle of retinoscopy, types of retinoscopes, step-by-step procedure, clinical applications in objective refraction, interpretation of reflex movements, and common troubleshooting tips. Designed for optometry students and eye care professionals, the content emphasizes clinical relevance and practical learning.

1. Retinoscope Ms. Reshu Yadav Assistant Professor SHS CSJM UNIVERSITY

2. RETINOSCOPY Retinoscopy introduced by Bowmann in 1859, is also known as skiascopy or Shadow test or Pupilloscopy or koreoscopy. It is an objective method of finding out the error of refraction by utilizing the technique of neutralization.

3. Principle of Retinoscopy Focault’s principle . It is based on the fact that when light is reflecting from a mirror into the eye, the direction in which the light will travel across the pupil will depend upon the refractive status of the eye.

4. Optics of Retinoscopy In retinoscopy, an area of the fundus is illuminated by the light reflected into the patient’s eye with the help of a retinoscope. This illuminated area serves as an object & the rays which emanate from this area illuminate the pupillary area & forms its image at the far point of the eye. When the immediate source of light is moved across the eye, the behaviour of the luminous reflex in the pupil will depend upon the refractive status of the eye.

5. Pre- requisites for Retinoscopy A dark room, preferably 6m distance. A trial set/box A trial frame Distance vision chart Near vision chart Retinoscope

6. Retinoscope Retinoscope is a simple device to perform the retinoscopy. Retinoscopes available are of two types- Reflecting mirror retinoscope Self-illuminating retinoscope

7. Reflecting mirror Retinoscope They are cheap & the most commonly employed. A source of light is required when using mirror retinoscope, which is kept above & behind the head of patient. The source of light used should be small, bright & enclosed, a pointolite is ideal. A mirror retinoscope may consist of a single plane mirror or a combination of plane & concave mirror (Priestly- smith’s mirror). Plane mirror gives comparatively more accurate results than the concave mirror.

8. The central aperture in this mirror should be 3-4mm in diameter so that a sufficient amount of light can enters the observer’s eye.

9. Self illuminating Retinoscope Self illuminating retinoscopes are costly but handy. Two types of self illuminating retinoscopes are available. These are- Spot retinoscope Streak retinoscope

10. Streak Retinoscope The illumination is provided by a special bulb that has a straight filament, thus forming a streak in its projection. The retinoscope is performed in the usual way & a band of light appears in the pupillary area which moves ‘with’ or ‘against’ the movement of band of light outside the pupil. The movement of the band of light is then neutralized by adding appropriate spherical lenses as describes in reflecting mirror retinoscopy. The streak retinoscope is more popular, since it is more sensitive than spot retinoscope in detecting astigmatism.

11. Procedure The patient is made to sit at a distance of 1m(per ease of calculation) from the examiner. However, a working distance 0f 2/3m is more convenient & so is preferred in practice. With the help of retinoscope, light is thrown into on the patient’s eye, who is instructed to look at a far point (to relax accommodation). However when cycloplegic has been used, the patient can look directly into the light & have the refraction assessed along the actual visual axis. Through a hole in the retinoscope mirror’s, the examiner observes a red reflex in the pupillary area of the patient. Then, the retinoscope is moved is horizontal & vertical meridian, keeping a watch on the red reflex.

12. Stages of Retinoscopy

13. Characteristics of moving retinal reflex are as follows- Speed & brilliance- In low degree of refractive error the shadow (red reflex) seen in the pupillary area is faint & moves rapidly with the movement of the mirror, whereas in high degree od ametropia it is very dark & moves slowly. Width of reflex- Narrow in high degree of ametropia & wide in low degree of ametropia. At the neutralization point, the entire pupil is filled with light. In the presence of astigmatism- When the axis does not correspond with the movement of the mirror, the shadow appears to swirl around.

14. Observation Depending upon the movement of the red reflex, the result are interpreted as follow- No movement- It indicates the myopia of 1D. With movement- It indicates the patient is either emmetropic, hypermetropic or myopia less than 1D. Against movement- It indicates the myopia of more than 1D.

15. Neutralization process Let’s suppose, we can put +1.00DS, this power gives on horizontal meridian with streak retinoscope. If it neutralize i.e no movement occur & if it occurs shows against movement, it means it highly neutralize than reduce a power which is given suppose it is neutralize with. Check another principle meridian & neutralize it with same process.