The optic nerve is the physical connection between the eye and the brain. Because of the importance of this connection, evaluating the health of the optic nerve is critical to assess both eye health and systemic health.
Swelling of the optic nerve is called papilledema, and is a medical emergency that may require neuroimaging, lumbar puncture, and hospitalization to determine the cause. However, between 1-2% of the population have a condition called optic nerve drusen that can mimic papilledema.
Optic nerve drusen is generally a benign condition that is most easily diagnosed using a function within the Optomap called autofluorescence. Autofluorescence is not visible with conventional dilated eye exams. An imaging device such as the Optomap is needed to assess the autofluorescence of the retina. In a normal autofluorescent image, the optic nerve will appear dark because there are no photoreceptors (rods and cones) or retinal pigment epithelium within the nerve (see below).
Normal autofluorescence darkness in an optic nerve
The following examples are of actual patients seen by Dr. Lewis that show optic nerve drusen, and how the Optomap was used to differentiate between the benign condition of optic nerve drusen and the medical emergency of papilledema.
Patient 1: 53 year old male. No vision complaints, just here for an updated glasses exam. No eye health concerns were noted at his last exam at another clinic. In the color Optomap image on the left, subtle elevation and blurring of the nasal border of the optic nerve can be seen. Is this papilledema and thus a medical emergency? The autofluorescent view on the right shows hyperautofluorescence on the superior nasal and inferior nasal border of the nerve that confirms the diagnosis of optic nerve drusen and not papilledema. Autofluorescence is not visible without imaging devices such as the Optomap.
53 year old male right eye
Patient 2: 45 year old female. Routine exam, no eye health concerns were discussed after her last dilated exam with an ophthalmologist here in Vancouver 1 year ago. In the color Optomap image on the left eye, there is subtle blurring and elevation of the nasal and inferior nasal optic nerve. So subtle that it was not seen at her last dilated exam (records were requested and there was nothing noted about the optic nerve appearance). Is this sudden onset papilledema and thus a medical emergency? The autofluorescent view on the right shows hyperautofluorescence on the nasal and inferior nasal border of the optic nerve that confirms the diagnosis of optic nerve drusen and not papilledema. Autofluorescence is not visible without imaging devices such as the Optomap.
45 year old female left eye
Patient 3: 51 year old female. Never had a formal eye exam, has only used reading glasses to get by for up close vision. In the color Optomap image on the left eye, there is subtle blurring and elevation of the nasal optic nerve. Is this papilledema and thus a medical emergency? The autofluorescent view on the right shows hyperautofluorescence on the nasal border of the optic nerve that confirms the diagnosis of optic nerve drusen and not papilledema. Autofluorescence is not visible without imaging devices such as the Optomap.
51 year old female right eye
Discussion
We still dilate patients when medically appropriate. However, dilation without also performing Optomap imaging with autofluorescence can leave incomplete information as these cases illustrate. This information can be incredibly helpful in determining whether a condition is benign, or a medical emergency. Autofluorescence is one of the many reasons why Dr. Lewis recommends that all patients have an Optomap during their routine exam.