Optimizing Uv-A Irradiation Profiles In Crosslinking For Progressive Keratoconus: A Comparison Of Outcomes After Standard Accelerated And Topography-Guided Protocols
Published 2024 - 42nd Congress of the ESCRS
Reference: FP18.10 | Type: Free paper | DOI: 10.82333/try0-ex11
Authors: Bruno Magalhães Teixeira* 1 , Telmo Cortinhal 1 , João Gil 2 , Pedro Gil 3 , Andreia Rosa 2 , Maria João Quadrado 2 , Joaquim Murta 2
1Ophthalmology Unit,Unidade Local de Saúde de Coimbra,Coimbra,Portugal, 2Ophthalmology Unit,Unidade Local de Saúde de Coimbra,Coimbra,Portugal;University of Coimbra,Faculty of Medicine,Coimbra,Portugal;Clinical Academic Center of Coimbra,Coimbra,Portugal;Coimbra Ophthalmology Unit,Coimbra,Portugal, 3Ophthalmology Unit,Unidade Local de Saúde de São José,Lisboa,Portugal;University of Coimbra,Faculty of Medicine,Coimbra,Portugal;Clinical Academic Center of Coimbra,Coimbra,Portugal
Purpose
To compare visual and tomographic outcomes of crosslinking treatment for progressive keratoconus, utilizing excimer-laser assisted epithelium removal and either central uniform irradiation (C-CXL) or customized topography-guided irradiation (TG-CXL).
Setting
Department of Ophthalmology, Unidade Local de Saúde de Coimbra (ULS Coimbra), Coimbra, Portugal; and Coimbra Ophthalmology Unit, Private Practice, Coimbra, Portugal.
Methods
Retrospective study. Patients with progressive keratoconus underwent TG-CXL or C-CXL. In both procedures the epithelium was removed using phototherapeutic keratectomy (PTK) with a 50 µm ablation within a 7.0 mm optic zone, followed by riboflavin application every 2 minutes for 10 minutes. In TG-CXL this was followed by topography-guided ultraviolet-A (UVA) irradiation, with treatment energies ranging from 10 to 5.4J/cm2 and fluence of 10mw/cm2. In C-CXL the cornea was uniformly irradiated with UVA using 6.0J/cm2 and fluence of 10mw/cm2. Visual, refractive, and tomographic data were collected at baseline, 6, and 12 months postoperatively.
Results
Fifty-four eyes from 48 patients were included (27 eyes for each group) with no significant baseline differences. Kmax significantly flattened at 1 year (-0.83±1.64 D; p=0.02) for TG-CXL, but not C-CXL (-0.46±2.04 D; p=0.256). Inferior-Superior asymmetry index decreased significantly at 1 year for TG-CXL (-8.17±9.56 D; p<0.01), but not for C-CXL (-3.69±11.69 D; p=0.11). Changes remained stable between 6 and 12 months in both groups. BCVA improved significantly at 1 year (difference to baseline: TG-CXL -0.13±0.14 logMAR; p<0.01 and C-CXL -0.24±0.38 logMAR; p=0.02; No difference between groups; p=0.24). There was a significant myopic shift in both groups (difference to baseline: TG-CXL -1.05±2.08 D; p=0.02 and C-CXL -0.90±1.49 D; p=0.03).
Conclusions
One year after surgery, TG-CXL leads to greater Kmax flattening and topographic regularization than C-CXL. Both procedures lead to improved visual acuity and a myopic shift. These results support the use of topography-guided crosslinking as a new valuable solution in the treatment of progressive keratoconus.