Blurring Strength & Aberrometric Changes Following Corneal Cross-linking (CxL) and CxL Combined With Photorefractive Keratectomy (PRK) in Keratoconus

Blurring Strength & Aberrometric Changes Following Corneal Cross-linking (CxL) and CXL Combined With Photorefractive Keratectomy (PRK) in Keratoconus.

Primary objective of this study was to assess the impact of the two prevalent therapeutic options, CxL and CxL combined with topography-guided photorefractive keratectomy (t-PRK), on both anterior and posterior corneal High order aberations (HOAs).

Study Overview

• Status: Completed
• Conditions: Keratoconus
• Intervention / Treatment: Procedure: Corneal Collagen Cross-Linking (CxL); Procedure: Corneal Collagen Cross-Linking combined with t-PRK

Detailed Description

The Pentacam Classic (Oculus Optikgerate GmbH, Heidelberg, Germany, software version 1.14r04) was used for the sake of the study.32 patients with keratoconus were included in the study. Of them, 19 patients underwent CxL treatment (CxL group), while the rest 13 patients underwent CxL combined with t-PRK (tCxL) [tCxL group]. If both eyes were eligible, only one eye was enrolled in the study.Regarding Scheimpflug camera (Pentacam Classic, Oculus Optikgerate GmbH, Heidelberg, Germany, software version 1.14r04 ) measurements, acceptable maps had at least 10.0mm of corneal coverage. Moreover, images with extrapolated data in the central 9.0mm zone were excluded.

For both anterior and posterior corneal surfaces, Pentacam-derived HOAs parameters for both pupil diameters of 4mm and 6mm were calculated, as well as the HOA root mean square (RMS)values. Pentacam-derived HOA measurements were obtained one day prior to treatment and then one year post-op.The impact of the surgical technique (either CXL or tCXL) on spherocylindrical error was evaluated by power vector analysis as described before. Furthermore, manifest refractions comprising of sphere (S), cylinder (C) and axis (φ), were converted into three dioptric powers (M, J0 and J45). Moreover, we calculated the overall blurring strength (B) of the spherocylindrical error by measuring the length of the produced vector.

• Study Type: Interventional
• Enrollment (Actual): 32
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Greece
  • Alexandroupolis, Greece
    • Eye Institute of Thrace (EIT)

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• progressive keratoconus

Exclusion Criteria:

• glaucoma or suspicion for glaucoma,
• central corneal thickness (CCT) less than 400μm,
• K-readings more than 60D,
• history of herpetic keratitis,
• pregnancy or nursing,
• underlying autoimmune disease

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: CxL group; Volunteers of this group received CxL treatment.	Procedure: Corneal Collagen Cross-Linking (CxL); The same surgical procedure was applied to all keratoconus patients that included: Instillation of proparacaine hydrochloride 0.5% drops for topical anaesthesia, application of a sponge saturated with 10% alcohol to the central cornea for 30 seconds and subsequent de-epithelialization by means of a hockey knife. Following de-epithelialization, a mixture of 0.1% riboflavin in 20% Dextran solution was instilled to the cornea for 30 minutes (2 drops every 2 minutes) prior to the irradiation, until the stroma was completely penetrated and aqueous was stained yellow. The UVA radiation source was UV-XTM Zurich, . Instillation of riboflavin drops (1 drop every 2 minutes) was continued during irradiation, as well, in order to sustain the necessary concentration of the riboflavin. Moreover, balanced salt solution (BSS) was applied every 6 minutes to moisten the cornea.
Experimental: tCxL group; Volunteers of this group received CxL combined with t-PRK treatment	Procedure: Corneal Collagen Cross-Linking combined with t-PRK; For tCxL group, the topo-guided PRK preceded the CXL. The epithelium was mechanically removed with a hockey knife and ablation was performed in a 9.0 mm zone with a maximal intended ablation depth of 50μm. No adjuvant Mitomycin-C was applied in any case. For the photorefractive ablation we used the Allegretto Wave 200 Hz (1.0071-1-0.81/1.208 software/ WaveLight AG, Erlangen, Germany) with the T-CAT ablation profile.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Higher order corneal aberations	1 year postoperatively

Collaborators and Investigators

• Sponsor: Democritus University of Thrace

Publications and helpful links

General Publications

• Labiris G, Sideroudi H, Angelonias D, Georgantzoglou K, Kozobolis VP. Impact of corneal cross-linking combined with photorefractive keratectomy on blurring strength. Clin Ophthalmol. 2016 Apr 1;10:571-6. doi: 10.2147/OPTH.S100770. eCollection 2016.

Study record dates

Study Major Dates

• Study Start: September 1, 2010
• Primary Completion (Actual): December 1, 2011
• Study Completion (Actual): January 1, 2012

Study Registration Dates

• First Submitted: February 3, 2012
• First Submitted That Met QC Criteria: February 6, 2012
• First Posted (Estimate): February 7, 2012

Study Record Updates

• Last Update Posted (Estimate): January 18, 2017
• Last Update Submitted That Met QC Criteria: January 14, 2017
• Last Verified: January 1, 2017

More Information

Terms related to this study

• Keywords: keratoconus; CxL; CxL combined with t-PRK
• Additional Relevant MeSH Terms: Eye Diseases; Corneal Diseases; Keratoconus
• Other Study ID Numbers: 3/2/2012 37