Start by a general observation, noting the shape and size of the pupil in ambient bright light. Size is measured in millimetres and the normal pupil ranges from 1-8 mm. Next, dim the light and have the patient fixate on the far wall. You can then observe the pupils closely by shining a bright light on the patient's face from below (minimise the shadow cast by the nose by placing the light in the midline). If you think there is size asymmetry, a good trick is to stand back and observe the red reflex of both eyes simultaneously with the ophthalmoscope. A slight difference will then become more apparent. If you have access to a slit lamp, use it as a lot of more detailed information can be gauged about the abnormally shaped pupil.Assessing pupillary reflexes There are essentially three reflexes to specifically test for Light reflex test
What it assesses - the integrity of the pupillary light reflex pathway. How to perform it - dim the ambient light and ask the patient to fixate a distant target. Illuminate the right eye from the right side and the left from the left side. (Make sure you do not stand in front of the patient, as their pupils will accommodate to focus on you.) Record whether there is a direct pupillary response (the pupil constricts when the light is shone on it) and a consensual response (the fellow pupil constricts too). Normal test - there should be a brisk, simultaneous, equal response of both pupils in response to light shone in one or the other eye.