Intrastromal Correction of Ametropia by a Femtosecond Laser

Intrastromal Correction of Ametropia by a Femtosecond Laser

This study evaluates the intrastromal correction of ametropia with a femtosecond laser made by 20/10 PERFECT VISION. This laser generates a beam of ultrashort, infrared pulses which enables very precise cuts in the cornea. By these cuts lamellae of the cornea are separated locally, and in the consequence the curvature of the cornea is changed, and the correction of the diagnosed ametropia can be achieved. On the contrary to cuts which are generated with a sharp knife, the cuts generated when using a laser can be generated just inside the cornea without opening the surface of the cornea. This means the procedure is minimal-invasive.

The study hypothesis is: Different types of ametropia can be corrected safely and on long-term by intrastromal cuts.

Inclusion Criteria:

• age: > 18 years
• stable distance refraction for at least one year (i.e. a maximum change of 0.5 D)
• in the case of presbyopia: minimum near add +2D to + 4D
• in the case of myopia or hyperopia (without astigmatism): minimal 1D and maximum 3D
• in the case of myopia or hyperopia (with astigmatism): spherical equivalent of minimal 1D and maximum 3D
• BSCVA of the eye to be treated >= 0.63
• patients are willing and in such conditions to come to the follow-up exams
• no further ocular pathologies

Exclusion Criteria:

• age: < 18 years

• refraction less than +/- 1 D or higher than +/- 3 D (not valid for presbyopia patients)

• minimal pachymetry of < 500µm

• K-mean < 37 D or > 60 D

• Difference (K-max minus K-min) > 5D

• Difference cycloplegic refraction to subjective refraction more than 1 D (valid only for hyperopia correction)

• patients with previous intraocular or corneal surgeries (e.g. post-LASIK or PRK patients). Exemption: standard cataract surgery.

• patients with one or more of the following ocular pathologies:

  • keratokonus
  • corneal scars
  • transplanted cornea
  • disorders of wound healing
  • trauma
  • glaucoma
  • epilepsia
  • nystagmus
  • lack of concentration
  • other complicated illnesses
  • diabetes mellitus
  • instable K-readings as a sign of instable cornea
  • weakness of connective tissue
  • sensitivity against the drugs used in the study
  • continuous wearing of contact lenses before the pre-exam, and before the surgery. At least 14 days before these dates patients must abstain from wearing CL.
  • patients in pregnancy or during lactation
  • patients who take part in another clinical trial