Clinical trial NCT04589091: Corneal Topography Asymmetry Indices Changes After Corneal Refractive Surgery
Official title: Corneal Topography Asymmetry Indices Changes After Corneal Refractive Surgery
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Myopia
Lead sponsor: Tanta University
Sponsor class: OTHER
First posted: 2020-10-19
Enrollment: 30
Sex: ALL
Minimum age (years): 19
Maximum age (years): 35
Standard ages: ADULT
Accepts healthy volunteers: no
Observational model: OTHER
Time perspective: RETROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: We will retrospectively review the medical records of all patients who underwent refractive surgery referred from the out-patient clinic of Tanta University hospital between September 2015 and September 2020

Brief summary: To evaluate the changes that occur in the corneal indices after corneal refractive surgery either PRK or LASIK.

Detailed description: Retrospectively review the medical records of all patients who underwent refractive surgery referred from the out-patient clinic of Tanta University hospital between September 2015 and September 2020 .

Data collection will include:

Preoperative and postoperative Evaluation: Age, sex, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest and cycloplegic refraction, Slit lamp biomicroscopy, fundus examination.

Data of Corneal Tomography keratometric using Scheimpflug camera (Pentacam Oculus- Germany) :that includes the following indices

1. Average keratometric value (K mean) in diopters
2. Maximum simulated keratometry (Kmax) in diopters
3. Index of Surface Variance (ISV) in microns
4. Index of Vertical Asymmetey (IVA) in microns
5. Radii Minimum (R min) in microns
6. Index of height asymmetry (IHA) in microns
7. Index of height decantation (IHD) in microns
8. Aberration coefficient (ABR)

The data of the pentacam will be collected pre-operative and analyzed at 1 month, 3 months and 6 months with recording of the complications.

Eligibility criteria: Inclusion Criteria:

* Patients who underwent refractive surgery either PRK, LASIK with age between 19 and 35 years old

Exclusion Criteria:

* Kertoconus.

  * Corneal scarring.
  * Previous corneal infections.
  * Minimum corneal thickness at the thinnest location less than 400 µm.
  * History of uveitis or ocular allergy.
  * Pre-existing glaucoma.
  * Data not available

Primary outcomes:
measure: To evaluate the changes that occur in the corneal indices after corneal refractive surgery either PRK or LASIK.
timeFrame: 6 months
Secondary outcomes:
Other outcomes:
Locations:
city: Tanta
country: Egypt
facility: Tanta University Hospital
state: El-Garbeia
Study officials:
References:
citation: Bailey MD, Zadnik K. Outcomes of LASIK for myopia with FDA-approved lasers. Cornea. 2007 Apr;26(3):246-54. doi: 10.1097/ICO.0b013e318033dbf0.
citation: Sridhar MS, Rao SK, Vajpayee RB, Aasuri MK, Hannush S, Sinha R. Complications of laser-in-situ-keratomileusis. Indian J Ophthalmol. 2002 Dec;50(4):265-82.
citation: Mohammadi SF, Nabovati P, Mirzajani A, Ashrafi E, Vakilian B. Risk factors of regression and undercorrection in photorefractive keratectomy: a case-control study. Int J Ophthalmol. 2015 Oct 18;8(5):933-7. doi: 10.3980/j.issn.2222-3959.2015.05.14. eCollection 2015.
citation: Belin MW, Ambrosio R Jr. Corneal ectasia risk score: statistical validity and clinical relevance. J Refract Surg. 2010 Apr;26(4):238-40. doi: 10.3928/1081597X-20100318-01. No abstract available.