Practical F.O.U.R.: How PERRLA is measured

What is PERRLA?

PERRLA is an acronym used to describe the look and function of the patient's eye.

PERRLA represents:

Pupils
Equal
Round
Reactive to
Light and
Accomodation

How is PERRLA measured?

Pupils
Pupils, in PERRLA stands for the presence of pupils in the patients eye. The clinician can simply look into the patient's eye to check for the presence of the pupil or with the help of the pen torch (to better illuminate the eye), check for the presence of the pupil in both eyes.

Equal
This stands for the size of the pupil. The clinician is required to measure the pupil of both eyes and compare whether or not are of equal size. A ruler is used to measure the size of the pupil in both photopic (bright) and scotopic (dark) conditions. To measure the pupil size in a scotopic condition, the Burton's lamp is used to illuminate the eye. The measurement of the pupil size in a scotopic condition can be seen in the second video inserted below.

Round
This represents the shape of the pupil. While a normal pupil should be round,the clinician should take note if the pupil is observed to be of any other shape. The clinician can observe the shape of the pupil with or without the help to a pen torch to illuminate the eye (shown at an angle below the eye and not directly).

Reactivity to Light
This represents the reactivity of the pupil to a light stimulus, meaning which the amount of time taken for the pupil to constrict when slight is shone upon it. The clinician uses a pen torch to shine a beam of light unto the patient's eye and observes the speed of constriction. This is done on both eyes. The speed of constriction should be almost immediate in a normal eye. The clinician will recorded the speed in different grades,3++ being normal reaction to light.

Reactivity to Accommodation
Accommodation occurs when the patient is required to look from a far object to a near object. During accommodation, the pupils will constrict and convergence will be observed as well. The clinician will have to observe this change in pupil size and eye movement. The eye's reactivity to accommodation is recorded down and ranked in the same way as the reactivity to light (3++ being the normal reaction). The first video attached below illustrates the convergence and constriction when fixating form far target to near target as well as divergence and dilation when fixating from near target to far target.