Simultaneous Corneal Wavefront-Guided Trans-PRK and Corneal Collagen Crosslinking After ICRS Implantation for Moderate Keratoconus
Condition: Moderate Keratoconus
MeSH terms: Keratoconus
Study type: Observational

Summary: 
      The investigators aim to investigate the effects of combined corneal wavefront-guided
      transepithelial photorefractive keratectomy (tPRK) and accelerated corneal collagen
      cross-linking (CXL) after intracorneal ring segment (ICRS) implantation in patients with
      moderate keratoconus. Medical records of 23 eyes of 23 patients undergoing combined tPRK and
      CXL after ICRS implantation were retrospectively analyzed. Uncorrected distance visual acuity
      (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent
      (MRSE), corneal indices based on Scheimpflug tomography, higher-order aberrations (HOAs), and
      corneal biomechanical properties were evaluated before and after ICRS implantation, and at 1,
      3, and 6 months after combined tPRK and CXL. Corneal biomechanical properties were measured
      using the dynamic Scheimpflug analyzer at approximately the same time of day.
    

Detailed description: 
      The investigators aim to investigate the effects of combined corneal wavefront-guided
      transepithelial photorefractive keratectomy (tPRK) and accelerated corneal collagen
      cross-linking (CXL) after intracorneal ring segment (ICRS) implantation in patients with
      moderate keratoconus. Medical records of 23 eyes of 23 patients undergoing combined tPRK and
      CXL after ICRS implantation were retrospectively analyzed. Uncorrected distance visual acuity
      (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent
      (MRSE), corneal indices based on Scheimpflug tomography, higher-order aberrations (HOAs), and
      corneal biomechanical properties were evaluated before and after ICRS implantation, and at 1,
      3, and 6 months after combined tPRK and CXL. Corneal biomechanical properties were measured
      using the dynamic Scheimpflug analyzer at approximately the same time of day. The dynamic
      Scheimpflug analyzer automatically calculated corneal deformation amplitude, radius values,
      and maximal concave power when the cornea is deformed to its greatest curvature by the air
      puff. The deformation amplitude is defined as the maximum amplitude when the cornea is
      deformed to its greatest concave curvature and is influenced by corneal stiffness. The radius
      values represent the central concave curvature at the highest concavity (depressed to the
      highest concavity), while maximal concave power is the inverse radius of the curvature at the
      highest concavity.
    

Intervention name(s): combined corneal wavefront-guided transepithelial photorefractive keratectomy (tPRK); accelerated corneal collagen cross-linking (CXL)
Intervention type(s): Procedure; Procedure
Intervention description(s): After at least 1 month (average 2.7 ± 1.1 months; range 1 to 4 months), all patients were scheduled for combined corneal wavefront-guided tPRK and accelerated CXL treatment. tPRK between the corneal ring segments was performed using an excimer laser (Amaris 1050 Excimer Laser platform; Schwind eye-tech-solutions GmbH and Co KG, Kleinostheim, Germany).; After at least 1 month (average 2.7 ± 1.1 months; range 1 to 4 months), all patients were scheduled for combined corneal wavefront-guided tPRK and accelerated CXL treatment. tPRK between the corneal ring segments was performed using an excimer laser (Amaris 1050 Excimer Laser platform; Schwind eye-tech-solutions GmbH and Co KG, Kleinostheim, Germany).
Observational model: Case-Only
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        Patient was intolerant to contact lenses, had moderate keratoconus without apical scarring,
        and if progression had been noted over the previous 6 months. All included patients
        underwent combined corneal wavefront-guided tPRK and CXL at least 1 month (average 2.7 ±
        1.1 months; range 1 to 4 months) after ICRS implantation. We excluded patients with central
        or para-central corneal scarring, central pachymetry < 400 microns, corneal endothelial
        cell density of less than 2000 cells/mm2, systemic autoimmune disease, a history of
        herpetic corneal disease, pregnancy, lactation, or severe dry eye syndrome.