Errors in Pupil Assessment

Proper pupil assessment technique is THE most important skill every ophthalmic assistant must possess.  If you employ improper technique you will miss pupillary abnormalities which may be a sign of a life threatening condition.

Why We Check Pupils

Life threatening conditions such as brain aneurysms, brain tumors, optic neuropathies cranial nerve palsies, carotid artery aneurysms and cancerous tumors can cause abnormal pupillary responses.  You can help save a life by discovering pupillary abnormalities.

Error #1:  Not using a bright test light or blocking the test light with your finger. 

You cannot properly assess pupils without using a bright test light. Some technicians erroneously think they are doing light sensitive patients a favor by dulling the test light with a finger; however you will miss subtle pupil abnormalities if you do.   In many ways, subtle pupil defects are more important to identify than obvious pupil defects because eyes with subtle defect frequently do not not have associated signs and symptoms.

Patients who are photo-phobic may need what I like to call 'vocal anesthesia' meaning you talk them through it.   Encourage the patent by saying 'I know it's bright... you're doing great..  bear with me... we're almost done."

Error #2: Checking pupils with room lights on. 

How can you observe the pupils' full response to light if you begin the test with the pupil already constricted due to the room light?  Use ambient room light, which is just enough light to observe the patient but not enough light to constrict the pupils.

Error #3: Not measuring pupil size.

Pathological and life threatening conditions such as Horner's Syndrome, III Cranial Nerve Palsies and brain aneurysms can cause anisocoria, a condition in which the pupils are > 1 mm difference in size.  When anisocoria is present, measure and document pupil size with indirect illumination with the room lights on and off.  Pupils that vary in the amount of anisocoria in dark and light are more suspect of having a pathological condition.

Proper pupil assessment technique is a critical skill every ophthalmic assistant must develop. Never take short cuts when it comes to pupil assessment. If you're in doubt about whether pupils are abnormal, ask your physician to assess the pupils prior to dilation.