**Question:** A 35 years old hypermetrope is using 1.50 D sphere both eyes. Whenever his glasses slip downward on his nose he will feel that his near vision:

**Core Concept:**

In hypermetropia (farsightedness), the eye has a longer focal length than normal, causing light rays to converge too far away from the retina. This results in blurry vision at near distances. When wearing glasses, the objective prescription (1.50 D sphere) compensates for this by correcting the refractive error. However, when the glasses slip downwards on the nose bridge, the lenses are no longer in their intended position to focus light correctly on the retina. This can lead to a temporary worsening of near vision due to improper light convergence.

**Why the Correct Answer is Right:**

The correct answer (D) explains the underlying mechanism of how farsighted individuals with glasses experience changes in vision when their glasses slip downwards. In the absence of proper lens alignment, the glasses cannot effectively correct the refractive error, resulting in worsening of near vision as the lenses are positioned further away from the intended focal point on the retina.

**Why Each Wrong Option is Incorrect:**

A. This option does not address the issue of improper lens alignment when glasses slip downwards.
B. This option discusses the effect of lens movement but does not explain the worsening of near vision in hypermetropic patients.
C. This option talks about the general impact of lens movement but does not address the specific situation of a hypermetropic patient experiencing worsening near vision due to glasses slipping downwards.

**Clinical Pearl:**

When wearing glasses, ensure the lenses are securely positioned on the nose bridge to prevent worsening of near vision or other visual disturbances caused by improper lens alignment. Regularly inspect and adjust your glasses to maintain optimal vision correction. In cases where glasses continuously slip due to nose bridge shape or size issues, consider consulting an optometrist for proper nose pad adjustment or consultation about contact lenses as an alternative vision correction method.