Which Purkinje image forms a real and inverted image?

The Purkinje images are reflections of light from the surfaces of the eye and are often used in ophthalmic measurements. The second Purkinje image, commonly known as PS 2, is typically formed at the anterior surface of the lens and is a real and inverted image.

In this context, the correct identification of the Purkinje image that forms a real and inverted image pertains directly to the properties of the optics involved. The real image is formed when light rays converge, as seen in PS 2, which corresponds to the reflection from the second surface of the cornea and is inverted due to the lens's optics.

Understanding the nature of these images is crucial for applications such as measuring intraocular pressure and evaluating corneal topography. The other Purkinje images—such as the first, third, and fourth—may have different characteristics, such as being virtual or upright, which helps to distinguish them in various optical assessments used in clinical practice.