Corneal Topography Asymmetry Indices Changes After Corneal Refractive Surgery

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

Study Overview

• Status: Completed
• Conditions: Myopia
• Intervention / Treatment: Other: Refractive surgery

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.

• Study Type: Observational
• Enrollment (Actual): 30

Contacts and Locations

Study Locations

• Egypt
  • El-Garbeia
    • Tanta, El-Garbeia, Egypt, 31515
      • Tanta university hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 19 years to 35 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• 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

Description

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

Study Plan

How is the study designed?

Design Details

• Observational Models: Other
• Time Perspectives: Retrospective

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Group(1): Patient who underwent PRK	Other: Refractive surgery; Refractive surgery for correction of error of refraction
Group(2): Patient underwent LASIK	Other: Refractive surgery; Refractive surgery for correction of error of refraction

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
To evaluate the changes that occur in the corneal indices after corneal refractive surgery either PRK or LASIK.	Using the results of measurements of Scheimpflug camera (Pentacam Oculus- Germany) :that includes the following indices; Average keratometric value (K mean) in diopters; Maximum simulated keratometry (Kmax) in diopters; Index of Surface Variance (ISV) in microns; Index of Vertical Asymmetey (IVA) in microns; Radii Minimum (R min) in microns; Index of height asymmetry (IHA) in microns; Index of height decantation (IHD) in microns; Aberration coefficient (ABR) The numbers from preoperative records will be compared with postoperative records after the refractive surgery is done . All the values will be expressed as mean ± standard deviation and the data will be analyzed as 1 months, 3 months and 6 months after surgery	6 months

Collaborators and Investigators

• Sponsor: Tanta University

Publications and helpful links

General Publications

• 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.
• 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.
• 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.
• 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.

Study record dates

Study Major Dates

• Study Start (Actual): April 13, 2021
• Primary Completion (Actual): October 30, 2021
• Study Completion (Actual): January 30, 2022

Study Registration Dates

• First Submitted: October 13, 2020
• First Submitted That Met QC Criteria: October 13, 2020
• First Posted (Actual): October 19, 2020

Study Record Updates

• Last Update Posted (Actual): February 8, 2022
• Last Update Submitted That Met QC Criteria: February 7, 2022
• Last Verified: February 1, 2022

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Eye Diseases; Refractive Errors; Myopia
• Other Study ID Numbers: 34081/9/20

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: Yes
• IPD Sharing Time Frame: 3 months
• IPD Sharing Access Criteria: Link
• IPD Sharing Supporting Information Type: Study Protocol

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No