Q50.3-2CC - Campbell Biology

Question

In a condition called presbyopia, the eyes’ lenses lose much of their elasticity and maintain a flat shape. How would you expect this condition to affect a person’s vision?

Step-by-Step Solution

Answer

The condition of presbyopia will result in altered vision; the affected individual would not focus on close objects with bare eyes as close focusing is attributed to the lens’s spherical shape.

Step 1: Light-detecting organ of humans

Humans are mammalian vertebrates that exhibit astonishing characters such as bipedal locomotion and verbal ability. These organisms have paired structures for detecting light and are placed on either side of the nose; it comprises a single lens and is termed eyes.

Step 2: Structure of the human eye

The eyes of humans have a spherical appearance and are located within the orbits. The three broad regions of the human eye are the fibrous tunic (outermost layer), uvea (middle layer), and the retina (innermost layer). The light-detecting photoreceptor cell is located within the retina.

Step 3: Effect of presbyopia

There are several diseased conditions of the eyes; presbyopia is one such disease. It decreases the eye’s elasticity and gives it a flatter appearance. As a result of this, the affected person’s vision is affected.

A person affected with presbyopia will be able to focus on a far object perfectly. However, as the ability to focus on close objects is regulated by the spherical shape of the eye, such a person will have blurred vision of closely kept objects.