Map dot fingerprint dystrophy (MDFD), also known as epithelial basement membrane dystrophy, is an incredibly common but frequently overlooked cause of a range of problems in the eye. The goal of this blog is not to reiterate what we already know about basement membrane dystrophy but to point out some lesser known sequela of this condition.
First, patients can lose vision from MDFD. Shown here is a clear example of how the irregularity in corneal topography matches nicely the map lines shown in the video. This patient lost 2 lines of vision from an irregular corneal surface.
Secondly, we all know about the morning pain symptoms that patients can have, and we know that MDFD can result in recurrent corneal erosions. However, in some patients, as in this case, MDFD did not result in pain upon wakening, but, instead, caused painless excessive tearing. (please see my blog on corneal erosion syndrome where pain is a symptom). The painless tearing results from a lacrimal gland response to overnight corneal injury. How then can there be no pain from the erosion? The patient likely has a neurotrophic cornea. I will dedicate future blog posts to the interesting subset of patients with a neurotrophic cornea.
Finally , MDFD is often misdiagnosed as dry eye. While dry eye can exacerbate and cause recurrences, and while improving lubrication is the first line of treatment, the underlining etiology is not dry eye, but in fact, corneal erosions. What is key here is not to immediately jump to a dry eye diagnosis when the patient presents with tearing. Also, taking a thorough history is key and sometimes even more important than physical findings. While the corneal findings in this case are obvious, subtle signs of map lines, dots, or fingerprints can be subtle and easily missed, especially underneath the upper eyelid.
In summary, there are 3 take home messages here. First, MDFD can result in a significant decrease in vision. Second, painless, excessive tearing can be the only symptom. Third, MDFD is frequently misdiagnosed as dry eye syndrome which was a diagnosis that was given to this patient . #cornealerosion #mapdotfingerprintdystrophy #basementmembranedisease #dryeyes #cornea #tearing #topography #visionloss