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

Sponsor

Democritus University of Thrace (Other)

Overall Status

Completed

CT.gov ID

NCT01527721

Collaborator

(none)

Enrollment

Location

Arms

Duration (Months)

Patients Per Site Per Month

Study Details

Study Description

Brief Summary

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).

Condition or Disease	Intervention/Treatment	Phase
Keratoconus	Procedure: Corneal Collagen Cross-Linking (CxL) Procedure: Corneal Collagen Cross-Linking combined with t-PRK	N/A

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 Design

Study Type:

Interventional

Actual Enrollment :

32 participants

Allocation:

Non-Randomized

Intervention Model:

Parallel Assignment

Masking:

None (Open Label)

Primary Purpose:

Treatment

Official Title:

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

Study Start Date :

Sep 1, 2010

Actual Primary Completion Date :

Dec 1, 2011

Actual Study Completion Date :

Jan 1, 2012

Arms and Interventions

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.

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.

Outcome Measures

Primary Outcome Measures

Higher order corneal aberations [1 year postoperatively]

Eligibility Criteria

Criteria

Ages Eligible for Study:

18 Years and Older

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

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

Contacts and Locations

Locations

	Site	City	State	Country	Postal Code
1	Eye Institute of Thrace (EIT)	Alexandroupolis		Greece

Sponsors and Collaborators

Democritus University of Thrace

Investigators

None specified.

Study Documents (Full-Text)

None provided.

More Information

Publications

None provided.

Responsible Party:

Georgios Labiris, Senior Lecturer of Ophthalmology, Democritus University of Thrace

ClinicalTrials.gov Identifier:

NCT01527721

Other Study ID Numbers:

3/2/2012 37

First Posted:

Feb 7, 2012

Last Update Posted:

Jan 18, 2017

Last Verified:

Jan 1, 2017

Keywords provided by Georgios Labiris, Senior Lecturer of Ophthalmology, Democritus University of Thrace

keratoconus

CxL

CxL combined with t-PRK

Additional relevant MeSH terms:

Keratoconus

Study Results

No Results Posted as of Jan 18, 2017