MCQ – 84583

Correct Answer � B Explanation

The given image represents Simple Myopic Astigmatism, where light comes to two focal points: one before the retina, and one on the retina.

• Astigmatism is a refractive error that creates an asymmetric blur in the vision due to the irregular corneal curvature/shape (corneal astigmatism) or the lens (lenticular astigmatism). 
•  Due to this condition, the light rays that enter the eye fail to converge at a single focal point on the retina and form two foci instead. 
• The lack of a single point focus results in the formation of blurred images on the retina.

The Five Different Types of Astigmatism

• With all types of astigmatism, light rays come together to form not one but two focal points. The mere fact that there are two focal points formed, instead of just one (in the normal seeing eye) creates vision problems.

First Type:
The first type of astigmatism is called Simple Myopic Astigmatism, where light comes to two focal points: one before the retina, and one on the retina.

Second Type:
The second type is called Simple Hyperopic Astigmatism, where light comes to two focal points: one on the retina and another focal point that would be a virtual point behind the retina.

Third Type:
The third type is called Compound Myopic Astigmatism where light comes to two focal points, both of which are before the retina but at two different locations before the retina.

Fourth Type:
 The fourth type is called Compound Hyperopic Astigmatism where light comes to focal points both of which would be in a virtual location behind the retina but at different virtual locations behind the retina.

Fifth Type:
The fifth type is called Mixed Astigmatism where light rays come to two focal points, one of which is before the retina and the other of which is behind the retina.