OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What causes some people to be short-sighted?

1. The lens is too thin

2. The lens is the wrong shape or the eyeball is too long

3. Light is not bending enough

4. Aging of the retina

The correct answer is: The lens is the wrong shape or the eyeball is too long

Short-sightedness, or myopia, occurs when the light entering the eye is not focused accurately on the retina. This misalignment happens either because the eyeball is elongated or because the cornea (the clear front surface of the eye) or lens is shaped in a way that causes light to bend too much. In the correct answer, the mention of the lens being the wrong shape or the eyeball being too long is accurate because these conditions lead to an increased focal length, meaning that light rays converge before they reach the retina. As a result, distant objects appear blurry while close objects can be seen clearly. Other options touch on various aspects of vision but do not directly address the underlying cause of short-sightedness. For example, a lens that is too thin or light not bending enough typically relates to different visual impairments, such as hyperopia (farsightedness). Aging of the retina is also a different condition, more commonly associated with other issues such as presbyopia.