Coa Accomodation

Front 1

Cycloplegics drops paralyze what muscle?

Back 1

Sphincter muscle that controls the iris, and ciliary muscle suspending accommodation. Tropicamide and cyclopentalate are two examples of this drop.

Front 2

Mydriatic drop?

Back 2

A mydriatic, such as phenylephrine (a poor dilator by itself), works with cycloplegics to boost dilation by stimulating the dilator muscle of the iris.

Front 3

The Near Point of Accommodation and the Amplitude of Accommodation

Back 3

The amplitude of accommodation is the inverse (reciprocal) of the near point expressed in meters. Suppose you measure the near point of accommodation to be 14 cm. We must first convert this to meters by moving the decimal point two spaces to the left. Therefore, 14.0 centimeters becomes .14 meters. The reciprocal is found by dividing this number into 1. You might want to do this with your cellphone.

1/.14 = 7.14 diopters of accommodative ability

Front 4

Another example of amplitude of accommodation is

Back 4

Let's take a closer look at the 45 year old. The amplitude of accomodation is 3.5 diopters. Half of 3.5 is 1.75. We need 2.5 diopters of power to focus at 16 inches, so we subtract 1.75 from 2.5 to get the shortfall in power, which is .75 diopter. Thus our 45 year old would need an add of about +1.00, which is what many age/add tables will give you.

This measurement is particularly useful in the evaluation of the patient who seems to be out of the normal range. For example:

the younger patient (< 40) who has reading difficulty and may need an add power
the older patient with a glasses complaint who may have been given an add that is too strong