Amplitude of accommodation

Amplitude of Accommodation is a term used in optometry and ophthalmology to describe the eye's ability to adjust its focus from distant to near objects (and vice versa). This process is achieved through the lens inside the eye changing its shape, a process known as accommodation.

Overview

The amplitude of accommodation refers to the maximum amount of accommodation a person can achieve without visual discomfort. It is measured in diopters, the unit used to measure the refractive power of the lens. The higher the amplitude of accommodation, the greater the eye's ability to focus on near objects.

Factors Influencing Amplitude of Accommodation

Several factors can influence the amplitude of accommodation. These include age, general health, and the presence of certain eye diseases.

Age

The amplitude of accommodation decreases with age, a condition known as presbyopia. In early childhood, the amplitude of accommodation can be as high as 20 diopters. By the age of 45, it typically decreases to about 4.5 diopters, and by the age of 60, it can decrease to 1 diopter or less.

Health and Eye Diseases

Certain health conditions and eye diseases can also affect the amplitude of accommodation. For example, conditions such as diabetes and multiple sclerosis can cause a decrease in the amplitude of accommodation. Similarly, eye diseases such as cataracts and glaucoma can also affect the eye's ability to accommodate.

Measurement

The amplitude of accommodation is typically measured using a method called push-up or push-down amplitude of accommodation test. In this test, a small object is moved closer or further away from the eye until the object becomes blurry. The distance at which this occurs is then converted into diopters to give the amplitude of accommodation.

See Also

• Accommodation (eye)
• Presbyopia
• Diopter
• Optometry
• Ophthalmology