Clinical, Anatomical, and Densitometric Changes following Dresden vs. Accelerated Corneal Cross-Linking in Progressive Keratoconus

Abstract

Background To compare clinical, anatomical, and densitometric changes following Dresden (DCXL) vs. accelerated (ACXL) corneal UVA cross-linking (CXL; Avedro KXL, Geuder, Heidelberg, Germany) in progressive keratoconus (KC).

Methods and Material In this retrospective study, we analyzed 20 patients following DCXL (3 mW/cm², 30 min, 5.4 J/cm²) and 44 patients following ACXL (9 mW/cm², 10 min, 5.4 J/cm²) between January 2016 and February 2020. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), central corneal thickness (CCT), steepest keratometry (K_max), keratoconus index (KI), thinnest pachymetry (Pthin), and corneal densitometry (CD) were measured before and 3, 6, 12, and 24 months after CXL.

Results During the follow-up period, no changes in UCVA, BSCVA, K_max, KI, or Pthin occurred. CCT significantly decreased 3 months after DCXL (p = 0.032) and ACXL (p = 0.006). At the 12- and 24-month follow-up, CCT remained decreased in the DCXL (p = 0.035, 0.036, respectively) but not in the ACXL group. At the 12-month follow-up, the reduction in CCT was significantly greater in DCXL compared to ACXL (p = 0.012). At the 3-, 6-, 12-, and 24-month follow-ups, we found a significant increase in the anterior stroma CD following DCXL (p = 0.019, 0.026, 0.049, 0.047, respectively) but not ACXL. The CD changes were localized in the central concentric zones (0.0 to 6.0 mm). No intra- or postoperative complications occurred.

Conclusion ACXL and DCXL effectively halted KC progression. ACXL proved to be a safe time-saving alternative to conventional DCXL. DCXL led to a reduction in CCT and an increment in the CD of the central anterior stroma during 24 months of follow-up.

Zusammenfassung

Hintergrund Vergleich klinischer, anatomischer und densitometrischer Veränderungen nach Dresdner Protokoll (DCXL) vs. „accelerated“ Protokoll (ACXL) des UVA-Crosslinkings der Hornhaut (CXL; Avedro KXL, Geuder, Heidelberg, Deutschland) bei progressivem Keratokonus (KC).

Material und Methoden In dieser retrospektiven Studie analysierten wir 20 Patienten nach DCXL (3 mW/cm², 30 min, 5,4 J/cm²) und 44 Patienten nach ACXL (9 mW/cm², 10 min, 5,4 J/cm²) zwischen Januar 2016 und Februar 2020. Die unkorrigierte Sehschärfe (UCVA), die bestkorrigierte Sehschärfe (BSCVA), die zentrale Hornhautdicke (CCT), der maximale Hornhautbrechwert (K_max), der Keratokonusindex (KI), die dünnste Pachymetrie (Pthin) und die Hornhautdensitometrie (CD) wurden vor sowie 3, 6, 12 und 24 Monate nach dem CXL analysiert.

Ergebnisse Während der Nachbeobachtungszeit traten keine Veränderungen in UCVA, BSCVA, K_max, KI oder Pthin auf. Die CCT nahm 3 Monate nach DCXL (p = 0,032) und ACXL (p = 0,006) signifikant ab. Bei der 12- und 24-monatigen Nachuntersuchung blieb die CCT in der DCXL- (p = 0,035 bzw. 0,036), nicht aber in der ACXL-Gruppe verringert. Bei der 3-, 6-, 12- und 24-monatigen Nachuntersuchung fanden wir eine signifikante Zunahme der anterioren Stroma-CD nach DCXL (p = 0,019, 0,026, 0,049 bzw. 0,047), nicht aber nach ACXL. Die CD-Veränderungen waren in den zentralen konzentrischen Zonen (0,0 bis 6,0 mm) lokalisiert. Es traten keine intra- oder postoperativen Komplikationen auf.

Schlussfolgerung ACXL und DCXL haben die Progression des KC erfolgreich aufgehalten. ACXL erwies sich als sichere, zeitsparende Alternative zur konventionellen DCXL. DCXL führte innerhalb von 24 Monaten postoperativ zu einer Verringerung der CCT und einer Zunahme der CD des zentralen anterioren Stromas.

Conclusion Box

Already known:

• DCXL is a well-established treatment option to halt KC progression.

• Based on the Bunsen-Roscoe law of reciprocity, ACXL is theoretically equally efficient to DCXL. However, its clinical equivalence remains unclear.

Newly described:

• A significant decrease in CCT was witnessed in the DCXL and ACXL groups at the 3-month follow-up and persisted only in the DCXL group until the 24-month follow-up.

• Total anterior stroma CD was significantly elevated only in the DCXL group. The CD elevations were localized in the central concentric zones (0.0 to 6.0 mm).

Key words

keratoconus - cornea - Dresden protocol - accelerated protocol

Schlüsselwörter

Crosslinking - Keratokonus - Hornhaut - Dresden-Protokoll - Accelerated Protokoll Crosslinking

Publication History

Received: 06 June 2023

Accepted: 31 October 2023

Article published online:
17 January 2024

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