What does aphakia refer to?

Aphakia specifically denotes the absence of the lens of the eye. This condition can occur as a result of surgical removal of the lens, often due to cataracts, or as a consequence of trauma or another eye disease. The absence of the lens significantly affects the eye's ability to focus light correctly on the retina, leading to issues with vision clarity.

While other options describe different eye-related conditions, they do not accurately define aphakia. For instance, a defect in the refractive power of the eye can lead to various visual impairments, but it does not specifically reference the absence of the lens. Double vision is generally referred to as diplopia, which is distinct from aphakia. Lastly, the turning inward of the eyelid is known as entropion, which is also unrelated to the specific definition of aphakia. Hence, understanding that aphakia is about the lens's absence highlights its essential medical consideration in ocular health and vision correction.