Range of accommodation is the distance between
**Core Concept**
Range of accommodation, also known as the near point, is the closest distance at which an individual can focus their vision without effort, typically measured in meters or centimeters. This distance varies among individuals and is influenced by factors such as age, refractive error, and ciliary muscle function. The range of accommodation is a critical concept in ophthalmology and optometry.
**Why the Correct Answer is Right**
The range of accommodation is determined by the ciliary muscles, which contract or relax to change the shape of the lens. When the ciliary muscles contract, the lens becomes more spherical, increasing its refractive power and allowing for near vision. The range of accommodation is limited by the maximum contraction of the ciliary muscles and the degree of lens deformation. In individuals with presbyopia, the ciliary muscles lose their elasticity, reducing the range of accommodation and making near vision more difficult.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the range of accommodation is not measured between the eye and the object being viewed, but rather between the eye and the point at which the image is focused.
**Option B:** This option is incorrect because the range of accommodation is not a fixed distance, but rather a variable distance that changes depending on the individual and the task at hand.
**Option C:** This option is incorrect because the range of accommodation is not related to the distance between the eye and the ear.
**Clinical Pearl / High-Yield Fact**
The range of accommodation decreases with age, typically beginning in the early to mid-40s. This decrease is a hallmark of presbyopia, a common age-related refractive error.
**Correct Answer: D.**