Thick keratoconic cornea associated with posterior polymorphous corneal dystrophy

Area of Science:

• Ophthalmology
• Corneal Diseases
• Genetics

Background:

• This report details a unique case of bilateral keratoconus with posterior polymorphous corneal dystrophy (PPCD).
• The patient presented with unusually thick, non-edematous corneas, a presentation atypical for these conditions.

Observation:

• A 27-year-old myopic woman exhibited bilateral corneal protrusion, stromal/endothelial opacities, and steepening on topography.
• Pachymetry revealed central corneal thickness of 605μm (RE) and 612μm (LE).
• Specular microscopy showed reduced endothelial cell density with significant pleomorphism and polymegathism.

Findings:

• Clinical and paraclinical data suggest co-existing keratoconus and PPCD.
• The patient's significantly thickened corneas, without edema, represent an unusual finding compared to literature reports of corneal thinning in similar cases.
• The presence of generalized advanced corneal steepening and increased elevations further supports the diagnosis.

Implications:

• This case underscores the complex relationship between PPCD and corneal ectatic disorders like keratoconus.
• Further research into genetic factors is necessary to elucidate the association between PPCD and keratoconus, particularly in cases with atypical corneal thickness.
• The findings may prompt re-evaluation of diagnostic criteria and management strategies for patients presenting with overlapping corneal conditions.