Keratoconus

Keratoconus is an eye disease that usually begins in the teenage years, becoming more active between 20 and 30, and then more dormant from the age of 40. It always displays secondary symptoms such as allergies, short-sightedness, or astigmatism. The Cornea develops into a conical shape leading to a dilution of the central corneal area and reduced vision

There are several ways to treat the condition including glasses, hard gas permeable contact lenses (e.g.,FlexCone); soft contact lenses, (e.g.HydroCone); surgical procedures (e.g. grafting and corneal transplant) and Corneal collagen crosslinking with riboflavin.keratoconus_info

As a Keratoconus patient with glasses it is likely 2 or 3 pairs will be needed to cope with fluctuations in vision due to the changing shape of the cone. Hard gas permeable contact lenses will provide good vision but will always have associated ‘foreign body’ comfort issues, possible limited wearing times, as well as not being suitable for certain activities such as sports. Keratoconus is an eye disease which leads to a conical distortion and/or a progressive thinning of the central Cornea.

KeratokonusAt the beginning it often only effects one eye, however over the medium term the second eye follows. Most frequently it effects only the central region of the cornea, a linear ethiopathology can’t be proved. Males suffer Keratoconus more than females (ratio 2:1)

Often, a person who has keratoconus is Myopic, and in addition to the Myopia the cone-shaped distortions also creates irregular astigmatism. With glasses this ametropia is often not possible to correct 10/10.

A solution that avoids these problems and can greatly improve quality of life are soft HydroConecontact lenses, lenses specifically designed for all levels of Keratoconus.

Indication
Grading
After affects
Contact lenses

Keratoconus symptoms

Objective observation

  • Frequent refractive changes
  • Increase of astigmatism
  • Advanced Keratoconus can be determined with a horizontal observation of the eye

Subjective observation

  • Diplopia
  • Blur
  • Halo-effects

Possible causes for keratoconus:

  • Genetic imprinting
  • Metabolic reasons
  • Weak collagen corneal connective tissue
  • Frequent eye-grating can increase the chances of keratoconus
  • Fissure in the cornea, Corneal thinning
  • Thinning of cornea after Lasik
  • Stress

Although the condition of Keratoconus has been recognised for over 200 years, an unequivocal cause has not yet been defined Keratoconus progression and relative corrective progression Relatively smooth divergence between the central and peripheral corneal topography.

Alternatives to stabilise the corneal surface:

Crosslinking: A modern alternative to stabilise the cone
Intacs: 2 plastic parts are implanted into the cornea to decrease the irregularity.

Grading scale

(Table Grades 1-4) Amsler-Krumeich keratoconus classification
Krumeich criteria:

Grade Clinical criteria
Grade 1

  • eccentric corneal steepening
  • induced myopia and/or astigmatism ≤5D
  • corneal curves ≤ 48D
  • no corneal imprint

Grade 2

  • nduced myopia and/or astigmatism > 5D and ≤8D
  • corneal curves ≤ 53D
  • no central corneal imprint
  • corneal thickness ≥ 400 µm2

Grade 3

  • induced myopia and/or astigmatism > 8D and ≤10D
  • corneal curves > 53D
  • no central corneal imprint
  • corneal thickness 200-400 µm

Grade 4

  • eye examination (refraction) impossible
  • corneal curves > 55D
  • central corneal imprint
  • corneal thickness ≤ 200 µm

After affects with Keratoconus

  • Enduring red eye
  • Diplopia
  • Ghosting
  • Distortions
  • Photo-sensitivity
  • Dazzling and glare
  • Depleted facial muscles
  • Halos
  • Streaking effects
  • Decreased vision at twilight and at night
  • Dry eye and hypersensitivity
  • Decreasing comfort/tolerance of contact lens wear especially over longer periods of wear (e.g. they slip or even drop off the eye)
  • Decreased tear-quality

Kontaktlinsen bei Keratokonus

Traditionally, rigid gas permeable lenses are prescribed to patients with keratoconus, however soft alternatives now exist offering greater comfort and potentially longer wearing times. These soft lenses are manufactured in modern materials such as Silicone Hydrogel and are individually made to the patient’s requirements, optimising fit and vision. They can also offer the patient the option of occasional wear for hobbies and sports activities.

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  • HydroCone: Soft contact lenses for keratoconus stages 1-4
  • HydroCone P: Soft contact lenses for keratoconus stages 1-4 with the additional correction of presbyopia

SwissLens also offers conventional rigid gas-permeable contact lenses for keratoconus:

  • FlexCone: Rigid gas permeable contact lenses for keratoconus stages 1-4
  • FlexCone P: Rigid gas permeable contact lenses for keratoconus stages 1-4 with the additional correction of presbyopia