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

NCT ID: NCT01527721

Last Updated: 2017-01-18

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 32 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2010-09-30
• Study Completion Date: 2012-01-31

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).

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.

Conditions

Keratoconus

Study Design

• Allocation Method: NON_RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: NONE

Study Groups

CxL group

Volunteers of this group received CxL treatment.

Group Type: EXPERIMENTAL

Corneal Collagen Cross-Linking (CxL)

Intervention Type: PROCEDURE

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.

tCxL group

Volunteers of this group received CxL combined with t-PRK treatment

Group Type: EXPERIMENTAL

Corneal Collagen Cross-Linking combined with t-PRK

Intervention Type: PROCEDURE

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.

Interventions

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.

Intervention Type: 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.

Intervention Type: PROCEDURE

Eligibility Criteria

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

• Minimum Eligible Age: 18 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Democritus University of Thrace

OTHER

Sponsor Role: lead

Responsible Party

Georgios Labiris

Senior Lecturer of Ophthalmology

Responsibility Role: PRINCIPAL_INVESTIGATOR

Locations

Eye Institute of Thrace (EIT)

Alexandroupoli, , Greece

Countries

Greece

References

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.

Reference Type: RESULT

PMID: 27099464 (View on PubMed)

Other Identifiers

3/2/2012 37

Identifier Type: -

Identifier Source: org_study_id