Some instruments were used to aid us in the experiment. Namely the pen torch, Burton's lamp, digital camera, and the reading chart.
Each alphabet in PERRLA has a meaning; it is stated below together with the steps and questions that are needed to ask one while checking patient’s eyes:
• Pupils - Is the pupil present? We need to check whether if the subject has a pupil or else the 'Perrla' cannot continue.
As seen in the above picture, the above right eye has pupil present and it is round.
• Equal – both pupils must be equal in size.
• Round – both pupils must be round in shape and not any other shape.
the above picture seen above is the left eye and it is as round as the right eye. Both pupil are also round in shape. Thus, we can continue with the PERRLA experiment.
• Reactive to • Light – pupils must be reactive to light. If light is shone directly in the right eye, there must be a constriction of the right and the left pupil. Followed by dilation of both pupils when light is brought away. Direct papillary reflex takes place when light is shone directly on the retina of the same eye. Consensual reflex happened when the left eye constricts when light is flashed into the right eye, because portion of the retina is stimulated when light was flashed onto the right retina.
The above picture shows the pupil constricts when light is shone directly to the right eye. This shows direct pupil reflex.
This pupil, from the left eye has shown constriction even though light was shone on the right eye. This explains consensual pupil reflex.
• Accommodation – allow the subject to focus on an object. The size of subject’s pupil would be more dilated and larger when the object is brought closer to the eye. The size of subject’s pupil would become smaller and constricts as the object is being brought further away from the subject or when the subject is forced to view an object at a far distant. While using PERRLA in a photopic environment.
The picture above shows a Burton's lamp and its used to magnify the pupil to determine if the pupil is round and for measuring the pupil accurately. The picture shows how the burton's lamp is used to magnify the eye. A ruler is placed behind the Burton's lamp for measuring the pupil size.
Sources from: http://rarediseases.about.com/od/medicalterms/g/perrla.htm
http://www.opt.indiana.edu/riley/HomePage/Pupil_Abnormal/1_Saint_Pupil_Abnormal.html
While using PERRLA in a scotopic environment.
