Corneal Higher-order Aberrations
Conditions
Keywords
higher-order aberrations, Pentacam, Topolyzer, LASIK
Brief summary
Aim of work: To assess the agreement between placido-based topographer (wavelight allegro topolyzer vario) and scheimpflug -based (Oculus Pentacam ) regard measuring corneal higher order aberrations before and after LASIK.
Detailed description
Higher-order aberrations (HOAs) are small optical irregularities of the eye, which can have an impact on the quality of the retinal image. In contrast to lower order aberrations, these errors cannot be corrected with regular spectacles and most contact lenses. Additionally, HOAs are responsible for an array of visual symptoms including dysphotopsia, glare, as well as a reduction in contrast sensitivity. The cornea accounts for approximately 90% of ocular aberrations.Advances and breakthroughs in wavefront aberration measurement technology can help clinicians to better understand and manage corneal higher-order aberrations (HOAs), especially for the preoperative planning of corneal refractive surgery and cataract surgery.A recent study has shown that corneal HOAs can be a sensitive parameter to differentiate early keratoconus from normal eyes. Furthermore, corneal aberrations have been widely used to evaluate dry eye and orthokeratology.LASIK surgery is widely used in the correction of refractive errors It is well known that LASIK surgery induces high-order aberrations (HOA) .The main eye element involved in the generation of such aberrations is the first corneal surface. Currently, devices based on Placido-disc, Hartmann- Shack, ray tracing, or Scheimpflug are routinely used in clinical aberration measurement. Of which Pentacam is one of common instruments that can only measure corneal aberration (including anterior and posterior corneal surface) based on Scheimpflug technology. Also Allegro Topolyzer is a Placido-based topographer that can measure anterior corneal higher order aberrations (HOAs). A better understanding of the agreement of device measurements can provide clinicians with useful information for measuring, correcting, and monitoring aberrations around refractive and cataract surgery. Investigators , therefore, aimed to study the agreement between the two instruments in anterior corneal aberration measurement.
Interventions
DEVICEplacido-based topographer (wavelight allegro topolyzer vario) and scheimpflug -based (Oculus Pentacam )
An informed written consent will be obtained from all patients that will be included in this study. Patients in this study will undergo pentacam and topolyzer examination to asses corneal high order aberrations before LASIK procedure. Patients will be assigned to undergo LASIK. Follow up pentacam and topolyzer examination will be done 3 months after LASIK.
Sponsors
Assiut University
Study design
Observational model
OTHER
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to 45 Years
Healthy volunteers
No
Inclusion criteria
* Patients with refractive errors from +6 diopters to -8 diopters sphere and up to -6diopters cylinder.
Exclusion criteria
* Patients with systemic diseases such as diabetes. * keratoconus or keratoconus suspect, amblyopic eyes. * Patients with best corrected visual acuity (BCVA) not achieving 20/25. * glucoma * Previous ocular surgeries or trauma.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Agreement between placido-based topographer (wavelight allegro topolyzer vario) and scheimpflug -based (pentacam) | Before LASIK and 3 months after LASIK | Agreement between placido-based topographer (wavelight allegro topolyzer vario) and scheimpflug -based (pentacam) regard measuring corneal high order aberrations before and after LASIK. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Changes in high order aberrations after LASIK. | Before LASIK and 3 months after LASIK | Changes in high order aberrations after LASIK using pentacam and topolyzer |
Countries
Egypt
Contacts
Primary ContactNaglaa MA Abdelmohsen, MD
Outcome results
None listed