Rarely, it may cause acute vision loss with severe pain due to perforation of the cornea.

It is typically characterized by a clear, bilateral thinning (ectasia) in the inferior and peripheral region of the cornea, although some cases affect only one eye.

Pain is not typically present in pellucid marginal degeneration, and aside from vision loss, no symptoms accompany the condition.

However, in rare cases, PMD may present with sudden onset vision loss and excruciating eye pain, which occurs if the thinning of the cornea leads to perforation.

The cornea just above the region of thinning is of normal thickness, and may protrude anteriorly, which creates an irregular astigmatism.

[5] This is described as a "beer belly" appearance since the greatest protrusion occurs below the horizontal midline (unlike keratoconus).

[5] Corneal topography may show a "crab claw-like" appearance, a finding that is seen in both keratoconus and in pellucid marginal degeneration.

[11] There is evidence suggesting corneal collagen cross-linking may be beneficial for patients with pellucid marginal degeneration.

[12][13][14] Research shows some promising results by combining collagen cross linking with photorefractive keratectomy, or with topography-guided transepithelial surface ablation.

[7] Corneal transplant surgery may be difficult due to the peripheral thinning of the cornea, even with large and off-center grafts.

Transplantation of the entire thickness of the cornea (penetrating keratoplasty) may be performed if there is enough normal tissue present.

[15][16] Due to the thinning of the cornea, people with PMD are poor candidates for procedures such as LASIK and photorefractive keratectomy.