I couldn’t believe my eyes when I was scrolling through my Facebook feed on Monday.  First, I was shocked to hear of the passing of David Bowie, but I also noticed that along with this news, there were several stories about his iconic eye appearance.  I had always been told, and always believed, that David Bowie’s unusual eye appearance was due to heterochromia iridis…

I guess I was wrong! After reading a few of these articles, I found that the real reason David Bowie’s eyes appeared to be different colors was because he had anisocoria! Did you know that? Or had you also been duped into believing he had heterochromia?!

Here’s the Real Story…

Back when David Bowie was 15 years-old, he and his buddy (George Underwood) got into a bit of a scuffle over a girl that they both liked. During the fight, David Bowie took a sucker punch to the left side of his face. Bowie reportedly suffered a deep corneal abrasion from Underwood’s fingernail. Additionally, the trauma and force of the blow damaged Bowie’s iris, causing complete paralysis of his iris sphincter muscle. Therefore, his left eye was left permanently dilated and unresponsive to light stimuli, while his right eye was unaffected. 

So, David Bowie did not actually have two different colored eyes, although it appeared that way. Both of his eyes were blue, but because his pupil was so much larger in his left eye, it made the left eye appear much darker than his bright blue right eye. Most people would be a little peeved at their friend for causing such pain and a significant cosmesis issue; however, Bowie had remained good friends with Underwood and even thanked him for giving him his iconic look that worked perfectly with his unique style!

Anisocoria

With anisocoria being such hot topic at the moment, let’s take a minute to review some of its most common causes:

• Physiologic anisocoria: Approximately 20% of the population naturally has a slight different in the size of each pupil. The best way to test this is to measure the pupil size in both bright and dim illumination; the difference in pupil size should be the same. 
• Horner’s syndrome: Anisocoria due to Horner’s syndrome results from a lesion in the  oculosympathetic pathway. This lesion could be either central, preganglionic, or postganglionic, and is characterized by the classic triad of ptosis, miosis, and anhydrosis on the affected side. When a person has Horner’s syndrome manifest early in life (congenital Horner’s) the pigment of the iris stroma will fail to develop, and the person will display heterochromia iridis. 
• Mechanical anisocoria: Anisocoria can also be caused by trauma to the iris (as in Bowie’s case), from prior eye surgery, injury, or an inflammatory reaction that has resulted in synechia. 
• Adie’s tonic pupil: Damage to the ciliary ganglion or short ciliary nerves will produce an abnormal pupil known as an Adie’s pupil. Adie’s pupils have several features, including minimal reaction to light, slow and tonic near reflex, accommodative paresis, a larger pupil on affected side (initially), and cholinergic hypersensitivity of the denervated muscle. 
• Argyll Robertson Pupil: A lesion in patients with neurosyphilis causes excessive parasympathetic activity, resulting in small pupils. In these cases, there is no reaction to light, near reflex is normal, and pupils react normally to accommodation and convergence (light-near dissociation). Pupils are also irregular in shape and miotic, and dilate very poorly with mydriatics. 
• Oculomotor (3rd) nerve palsy: Patient’s presenting with a 3rd nerve palsy will exhibit an eye that is turned down and out, with a complete ptosis. In some (but not all) people, they will also present with a fixed, dilated pupil on the affected side. Lesions due to ischemia usually spare the pupil, but those due to compression lesions often affect the pupil size. 
• Pharmacological agents: Certain drops, medications, plant matter, etc. will cause dilation of the pupils if instilled into the eye. In most of these cases a thorough case history will help explain the anisocoria. Although, in some patients an offending agent cannot be identified and all other possibilities must be ruled out before coming to this conclusion. 

“If you’re sad today, just remember that the world is over 4 billion years old and you somehow managed to exist at the same time as David Bowie.”

-Dr. Dexter 

The Top 15 Tips and Tricks for Studying for Part I of NBEO^®

We’ve put together a ton of great tips and tricks for studying for Part I of NBEO along with two tailored study programs that will help you thoroughly prepare for the big day. Remember, you’ve made it this far and you can totally do this!

Some of the Top 15 Tips include:

• Familiarize Yourself with the Test Format
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