Clinical trial NCT01527721: Blurring Strength & Aberrometric Changes Following Corneal Cross-linking (CxL) and CxL Combined With Photorefractive Keratectomy (PRK) in Keratoconus
Official title: Blurring Strength & Aberrometric Changes Following Corneal Cross-linking (CxL) and CXL Combined With Photorefractive Keratectomy (PRK) in Keratoconus.
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Keratoconus
Keywords: keratoconus
CxL
CxL combined with t-PRK
Lead sponsor: Democritus University of Thrace
Sponsor class: OTHER
First posted: 2012-02-07
Enrollment: 32
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: NON_RANDOMIZED
Intervention model: PARALLEL
Primary purpose: TREATMENT

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.

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

Primary outcomes:
measure: Higher order corneal aberations
timeFrame: 1 year postoperatively
Secondary outcomes:
Other outcomes:
Locations:
city: Alexandroupolis
country: Greece
facility: Eye Institute of Thrace (EIT)
Study officials:
References:
citation: 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.