This document discusses Purkinje images, which are reflections formed in the eye. There are four Purkinje images formed by reflections off of different structures in the eye. The first image is formed by the anterior cornea, the second by the posterior cornea, the third by the anterior lens, and the fourth by the posterior lens. The fourth image is the only inverted and real image, while the others are erect and virtual. The first Purkinje image is the brightest, while the third is less bright than the fourth. These images have various clinical applications and appearances based on eye conditions.

1. Purkinje Images
Name:- Ayan Das
University Roll No. :- 16401722005
Stream:- Bachelor of optometry
Semester:- 3rd
Subject:- Visual Optics (Optics III)
Paper code:- BO-301

2. Introduction
• They are also known as Purkinje-Sanson images or Purkinje reflexes.
• Purkinje images are reflections of objects from the structure of eye.
• Purkinje-Sanson images are named after Czech anatomist Jan Evangelista
Purkyne (1787-1869) and after French physician Joseph Sanson (1790-
1841)

4. Mode of Image formation
• Images are formed due to reflection and refraction.
• 4 purkinje images are formed in the eye

5. Four Purkinje images
• 1ST Purkinje image is formed to anterior cornea
• 2nd Purkinje image is formed by posterior cornea
• 3rd Purkinje image is formed by anterior surface of lens
• 4th Purkinje image is formed by posterior surface of lens

6. Fig:- Four Purkinje images

7. Nature of image
• Out of the 4 images P4 is the only Inverted and Real image.
While the other images are Erect and Virtual.
• P3 image is larger than other image.

8. Brightness of image
• Purkinje image P1 Image is the brightest of the four image.
• P2 image is mild bright.
• P3 have a less brighter intensity than P4.

9. Clinical importance of Purkinje image
• Purkinje image 1 or P1 has many clinical applications including,
Keratometry and Corneal Topography.
• P1 is also used in measuring Angle kappa(Angle of deviation) in
‘Hirschberg Corneal Reflex’ test.

10. Purkinje images in Cataract and Aphakia
• In Patients with mature senile cataract—P4 image will be absent
• In Aphakia —P3 and P4 image will be absent

11. Eye tracking
• Eye tracking is the process of measuring either the point of gaze
(where on is looking) or the motion of an eye relative to the head.
• The first and fourth purinje images can be used for tracking the
Direction of gaze by the Dual-Purkinje image technique.

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