Question
| A. | Hypermetropia |
| B. |
Myopia |
| C. | Astigmatism |
| D. |
Presbyopia |
|
Correct Answer » C Explanation |
 |
Sturm’s conoid is a three-dimensional representation of astigmatism. It is a conical surface that is generated by plotting the refraction of light rays passing through a cylindrically shaped lens.
The curved lines represent the refractive power of the cylindrical lens at different points across the lens surface. The center of the conoid represents the point of zero astigmatism, while the outer edges represent the points of maximum astigmatism.
This image can be used to help understand and diagnose astigmatism, a common refractive error that causes blurred vision at all distances. Astigmatism occurs when the cornea or lens of the eye has an irregular shape, causing light rays to be refracted unevenly and focus at multiple points on the retina.
Sturm’s conoid provides a visual representation of how this uneven refraction occurs in cylindrical lenses, and can help eye care professionals design corrective lenses to compensate for the astigmatism.
