Special cases for healing the eye’s surface - Part 2: Map-Dot-Fingerprint Corneal Dystrophy (MDF).

Map-Dot-Fingerprint Corneal Dystrophy (MDF) is a specialized version of Recurrent Corneal Erosion (see my last post on RCE). Unlike RCE, no deep scratch is required to set up the cornea for these open sores, because MDF is a genetic disorder that causes patches of “poor topsoil,” so the “turf” of cells growing on the corneal surface have poor “root systems” to otherwise help them stick on. Like RCE, patients suffer from these open sores worst if they have poor tears and similarly are often aware of the sores when they first open their eyes in the morning. This is because the “rocky” topsoil tends to elevate the epithelial (turf-like) cells above the normally smooth surface and the eyelids tend to “stick” to these elevated “islands” of cells – so the friction of opening lids can tear these cells loose and cause sudden open sores (like RCE).

When there are elevations of small islands, they look like “Dots” when discrete, but when they form whorl-like patterns, they can mimic a “Fingerprint” or even the continent of a country “Map.” It commonly requires special dyes and special lighting at a slit lamp (the clinical microscope used in a detailed eye exam) to see them, as they will displace the dye - like an island “sticking up out of the ocean” (of tears). Many MDF dry eye patients have patchy affected areas and if they are small and not in the center of the cornea, they may cause little-to-no trouble. Bigger trouble comes from larger patches – especially if they are centrally located. These areas can act like a “wet rug,” where whole areas can slip and slide with blinking, until they “break open” and cause sudden pain. Affected eyes can cause blurry vision from the shifting irregularities of this surface and can cause light sensitivity from glare and tearing from tortured corneal nerves reacting to these open sores.

For eyes who have this genetic problem causing recurrent erosions or are centrally (visually) affected - especially if anticipating cataract surgery with centrally affected corneas, it is common to require scraping the “turf” and “poor topsoil” away to allow better, smoother resurfacing from healing. We covered the various ways to help smooth the “topsoil” out and promote a good “root system” in the last (RCE) post. The reason to apply this to centrally affected corneas – especially before cataract surgery – is because good readings of the corneal surface are critical to determining the type and power of the implants used to focus the eye after cataract surgery (and permanently placed at the time of that cataract surgery). A wrong reading can translate to a wrong implant and a need for thicker glasses after the surgery (to make up for the poor focus from a wrong implant). We will cover this issue in greater detail when we cover Salzman’s Nodular Corneal Dystrophy and pterygium as they relate to cataract surgery.

With great tears and smaller affected areas of MDF, most patients will never know they even have this problem. This is because they have the lubrication and support to help even weak roots “hang on” and create a smoother, more rugged surface. “Bad tears” – especially combined with larger patches of weaker-rooted surface cells, tend to have the worst problems. Better support (as in the best tears) always seems to heal these problems better and faster, so it pays to have a dry eye specialist assist when you have a problem like MDF Corneal Dystrophy.