Among the diseases affecting the eyes, there are also some rare ones, such as keratoconus, corneal degeneration, hereditary corneal dystrophies, and Axenfeld-Rrieger syndrome.

These diseases are rare and disabling, so eye examinations, early diagnosis, and innovative therapies are crucial to avoid invasive interventions, such as corneal transplantation.

Keratoconus

Keratoconus is a progressive bilateral alteration of the cornea, the transparent membrane located at the front of the eyeball, caused by the reduction of rigidity and thinning of the cornea, which becomes deformed until it resembles a cone. 

Keratoconus can manifest with blurred vision, which cannot be corrected using glasses, and perception of distorted and blurred images.

Keratoconus affects both eyes and is particularly common in adolescence, especially in cases where other family members are already affected or in the presence of allergies that cause allergic keratoconjunctivitis.

In cases of familiarity or the manifestation of initial disease symptoms, referring to specialized centers as soon as possible is essential. With an early diagnosis, when the first clinical symptoms do not yet appear (preclinical diagnosis), corneal transplantation can be avoided. 

Today, this is possible with modern technology that creates high-definition corneal tomographic maps and measures corneal stiffness (corneal biomechanics). In addition, with new technologies, it is possible to intervene with minimally invasive therapies called Corneal Cross-Linking with Vitamin B2 or riboflavin eye drops on the cornea’s surface activated by laser with UVA beams.

Hereditary Corneal Dystrophies

Hereditary dystrophies of the cornea are a group of disorders that affect both eyes and have a progressive development.

They can affect various eye areas and are divided into hereditary corneal epithelial, endothelial, Bowman’s membrane, and stromal dystrophies.

An alteration in the shape and function of the cornea characterizes hereditary corneal dystrophies. They generally occur between the ages of 10 and 40 with symptoms such as:

  • Visual impairment of varying degrees;
  • Opacification of the cornea; 
  • Dry eye. 

Again, with early diagnosis, through specialist examinations – especially if there is a family history of the disease – it is possible to avoid corneal transplantation, which is indicated in cases of severe vision reduction. 

Corneal degeneration

Corneal degeneration causes corneal opacity and affects people of different ages. It can occur in both eyes, but not always. 

Several forms of corneal degeneration are recognized: 

  • Gerontoxon, which occurs in old age with a gray-colored band across the entire outer circumference of the cornea, causing loss of visual acuity and corneal opacity;
  • Amyloidosis;
  • Hyaline degeneration;
  • Salzmann’s degeneration;
  • Terrien’s marginal degeneration.

Rieger’s syndrome (or Axenfeld-Rieger)

Rieger syndrome (also known as Axenfeld-Rieger) is often diagnosed at birth. It is a rare inherited genetic disorder that manifests with various malformations of the face, oral cavity, abdominal area, heart, and eyes at the level of the lens and the iris, often with glaucoma. 

There is no specific treatment for this condition, but the aim is to prevent the occurrence of glaucoma. Diagnosis and therapy are essential for glaucoma to prevent worsening symptoms to the point of blindness.