Chapter 26, Problem 1CQ

If the lens of a person’s eye is removed because of cataracts (as has been done since ancient times), why would you expect a spectacle lens of about 16 D to be prescribed?

To determine

Why would you expect a spectacle lens of about 16D to be prescribed?

Answer to Problem 1CQ

The power lens, in normal conditions, is between 50.0 D and 54.0 D, therefore, a prescription of 16.0 D for a spectacle lens is insufficient to correct the sight of a person whose lens has been removed.

Introduction:

Cataract is an anomaly that occurs in the eye, specifically in the lens's eye. This disease consists in the deterioration of the quality of the image produced by a total or partial opacity of the eye lens, causing the light to scatter inside the eye and not be able to focus on the retina.

Explanation:

If a person's lens is removed and a spectacle lens with a prescribed power of 16D is fitted in place, the patient's vision would be evenly blurred. In other words, a power lens of 16D would be insufficient to correct the patient's view knowing that in normal conditions the range of the power lens is between 50.0D (distant vision) and 54.0D (close vision)

Conclusion:

The power lens, in normal conditions, is between 50.0 D and 54.0 D, therefore, a prescription of 16.0 D for a spectacle lens is insufficient to correct the sight of a person whose lens has been removed.

Explanation of Solution

Introduction:

Cataract is an anomaly that occurs in the eye, specifically in the lens's eye. This disease consists in the deterioration of the quality of the image produced by a total or partial opacity of the eye lens, causing the light to scatter inside the eye and not be able to focus on the retina.

If a person's lens is removed and a spectacle lens with a prescribed power of 16D is fitted in place, the patient's vision would be evenly blurred. In other words, a power lens of 16D would be insufficient to correct the patient's view knowing that in normal conditions the range of the power lens is between 50.0D (distant vision) and 54.0D (close vision)

Conclusion:

The power lens, in normal conditions, is between 50.0 D and 54.0 D, therefore, a prescription of 16.0 D for a spectacle lens is insufficient to correct the sight of a person whose lens has been removed.