Map-dot-fingerprint dystrophy is a common eye condition that affects the clear, dome-shaped front surface of the eye known as the cornea. This disorder is also medically termed Anterior Basement Membrane Dystrophy (ABMD) or Epithelial Basement Membrane Dystrophy (EBMD). It involves an irregularity in the structure of the cornea’s outermost layer, which can cause the corneal surface to become uneven. While many individuals who have the condition remain unaware of it, the irregularity can sometimes lead to discomfort or vision issues. The condition is generally manageable, but it can be the source of significant pain for a subset of affected people.
Defining the Corneal Dystrophy
A corneal dystrophy is a group of disorders that cause material to build up in the cornea, often affecting its transparency and shape. Map-dot-fingerprint dystrophy specifically involves the cornea’s outermost layer, the epithelium, and its underlying foundation, the basement membrane. The epithelium acts as the protective skin over the eye.
The epithelial cells are meant to anchor securely to the basement membrane. In this dystrophy, the basement membrane thickens and becomes irregular, sometimes duplicating or migrating into the epithelial layer. This abnormality weakens the bond between the epithelium and the underlying layers of the cornea. Because the anchoring mechanism is compromised, the surface cells cannot adhere properly, creating the structural defect.
The official name, Anterior Basement Membrane Dystrophy, highlights this issue with the basement membrane at the front of the cornea. When the epithelial cells cannot properly stick down, it results in an unstable surface that can easily lift away from the rest of the eye. This instability is the root cause of the symptoms and the characteristic patterns seen by eye care professionals.
What the Patterns and Symptoms Mean
The condition gets its common name from the distinct patterns observed on the corneal surface during an eye examination. The “map” pattern refers to large, slightly grayish outlines that look like a landmass, which are sheet-like arrangements of abnormal basement membrane material. The “dots” are clusters of opaque, tiny cysts, or microcysts, that form in the epithelium due to trapped cell debris. These microcysts can rupture, contributing to surface instability.
The “fingerprint” pattern appears as fine, concentric, parallel lines that resemble actual fingerprints. These lines are folds or reduplications of the abnormal basement membrane extending into the epithelial layer. These patterns create an uneven corneal surface, which can cause light to scatter, leading to symptoms like blurred, fluctuating, or distorted vision.
The most painful symptom is recurrent corneal erosion, where the weakened epithelium spontaneously tears away from the underlying tissue. This event is extremely painful because the cornea is densely packed with nerve endings. Erosions typically occur upon waking in the morning because the eyelid can slightly adhere to the dried epithelial surface overnight, tearing it off upon the first opening of the eyes. Other common symptoms include a gritty or foreign body sensation, sensitivity to light, and excessive tearing.
Identifying the Cause and Diagnosis
The exact cause of Anterior Basement Membrane Dystrophy is often unknown, as it occurs sporadically without a clear trigger. While classified as a dystrophy, it is not always inherited, though autosomal dominant patterns have been observed in some families. A history of eye trauma or previous eye surgery can sometimes precipitate its development. The condition is common, affecting an estimated 2% to 43% of the general population.
Diagnosis is made by an ophthalmologist, who uses a specialized microscope called a slit lamp. This device allows the physician to examine the cornea in high magnification and visualize the characteristic map, dot, and fingerprint patterns. The patterns are most easily seen with reflected light, a technique called retroillumination. Corneal topography, which creates a detailed map of the corneal surface curvature, may be used to assess the degree of surface irregularity. The presence of these specific patterns, combined with patient history of recurrent erosions, confirms the diagnosis.
Treatment Options and Prognosis
Treatment aims to keep the corneal surface smooth, promote better adherence of the epithelium, and manage painful erosions. For mild cases or during a painful erosion episode, conservative management is the first step. This includes frequent lubricating eye drops and applying hypertonic saline drops or ointments, such as 5% sodium chloride, which help draw fluid out of the cornea to reduce swelling. A soft bandage contact lens may also be placed on the eye to protect the exposed tissue and promote healing.
If symptoms are persistent or severe, more advanced interventions may be necessary to remove the irregular tissue and encourage the growth of a new, healthier epithelial layer.
Advanced Interventions
A procedure called epithelial debridement involves gently scraping away the damaged surface cells, often followed by a treatment to strengthen the underlying adhesion. Phototherapeutic Keratectomy (PTK) uses an excimer laser to precisely remove the abnormal tissue and smooth the corneal surface. Anterior stromal puncture involves creating tiny, intentional scars in the underlying tissue to serve as stronger anchors for the regrowing epithelium.
The prognosis for people with map-dot-fingerprint dystrophy is generally favorable. The condition rarely results in severe or permanent vision loss, and many individuals remain asymptomatic throughout their lives. While the disorder can be chronic and symptoms may wax and wane, most cases are successfully managed with conservative medical treatment or minor procedures. Even after successful treatment, the patterns may recur, requiring ongoing monitoring by an eye care professional.