Margaux Metzger1, Valentin Navel2, Jean-Vincent Barrière3, Fabrice Kwiatkowski4, Jérémy Hébraud5, Aurélien Mulliez6, Laurence Béral7, Frédéric Chiambaretta8, Frédéric Dutheil9. 1. CHU, Clermont-Ferrand, University Hospital of Clermont-Ferrand, Ophthalmology, Clermont-Ferrand, France. margometzger@gmail.com. 2. Université Clermont Auvergne, CNRS, INSERM, GReD, Translational Approach To Epithelial Injury and Repair, CHU Clermont-Ferrand, University Hospital of Clermont-Ferrand, 63000, Ophthalmology, France. valentin.navel@hotmail.fr. 3. CHU, Clermont-Ferrand, University Hospital of Clermont-Ferrand, Ophthalmology, Clermont-Ferrand, France. 4. Laboratory of Mathematics, Université Clermont Auvergne, Blaise Pascal, Clermont-Ferrand, France. 5. Intensive Care Unit, CHU Clermont-Ferrand, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France. 6. CHU Clermont-Ferrand, University Hospital of Clermont-Ferrand, Biostatistics, Clermont-Ferrand, France. 7. CHU Pointe-À-Pitre Abymes, University Hospital of Pointe-À-Pitre Abymes, Ophthalmology, Pointe-à-Pitre, France. 8. Université Clermont Auvergne, CNRS, INSERM, GReD, Translational Approach To Epithelial Injury and Repair, CHU Clermont-Ferrand, University Hospital of Clermont-Ferrand, 63000, Ophthalmology, France. 9. CNRS, LaPSCo, Physiological and Psychosocial Stress, University Hospital of Clermont-Ferrand, CHU Clermont-Ferrand, Preventive and Occupational Medicine, WittyFit, Université Clermont Auvergne, Clermont-Ferrand, France.
Abstract
PURPOSE: In prospective no-masking, comparative, crossover monocenter clinical trial, we aimed to evaluate whether the optimal subjective refraction technique varies with the keratoconus topography and to identify relevant topographic criteria. METHOD: This study included 72 keratoconus eyes with impaired visual acuity. Each eye tested three methods of refraction (Jackson cylinder, astigmatism dial, stenopeic slit), resulting in three eyeglass lenses. Patients were assigned to the group corresponding to the eyeglass lens offering the best visual acuity. Five topographical characteristics were collected via the Pentacam: mean keratometry (Km), maximum keratometry (Kmax), distance from corneal center to Kmax (dKmax), Belin/Ambrosio Display (BAD_D), and index of surface variance (ISV). RESULTS: Forty-six eyes were included in the dial group (64.8%), 23 eyes in the cylinder group (32.4%), and only 2 eyes in the slit group (2.8%); thus, we only compared dial and cylinder groups. The main analysis retrieved a significant probability to choose dial technic for BAD_D (p = 0.024); when BAD_D is > 9.71 (ROC threshold), the positive predictive value (PPV) = 89.5%, and for ISV, p = 0.012; when ISV is > 77, PPV = 89.1%. The sub-analysis of patients with different visual acuities between cylinder and dial confirmed these results with slightly different thresholds: the probability to choose dial technic was for BAD_D, p = 0.03; when BAD_D is > 7.55, PPV = 90%, and for ISV, p = 0.0084; when ISV is > 71, PPV = 88.5%. CONCLUSION: Refraction method is linked to topographic indices ISV and BAD_D. A BAD_D > 7.55 indicates the dial method. In addition to keratoconus screening and diagnosis, this study suggests a new application of the topographer to select a suitable refraction method for eyeglass prescription. TRIAL REGISTRATION: Study registered on the ClinicalTrials.gov database under n°: NCT04174209.
PURPOSE: In prospective no-masking, comparative, crossover monocenter clinical trial, we aimed to evaluate whether the optimal subjective refraction technique varies with the keratoconus topography and to identify relevant topographic criteria. METHOD: This study included 72 keratoconus eyes with impaired visual acuity. Each eye tested three methods of refraction (Jackson cylinder, astigmatism dial, stenopeic slit), resulting in three eyeglass lenses. Patients were assigned to the group corresponding to the eyeglass lens offering the best visual acuity. Five topographical characteristics were collected via the Pentacam: mean keratometry (Km), maximum keratometry (Kmax), distance from corneal center to Kmax (dKmax), Belin/Ambrosio Display (BAD_D), and index of surface variance (ISV). RESULTS: Forty-six eyes were included in the dial group (64.8%), 23 eyes in the cylinder group (32.4%), and only 2 eyes in the slit group (2.8%); thus, we only compared dial and cylinder groups. The main analysis retrieved a significant probability to choose dial technic for BAD_D (p = 0.024); when BAD_D is > 9.71 (ROC threshold), the positive predictive value (PPV) = 89.5%, and for ISV, p = 0.012; when ISV is > 77, PPV = 89.1%. The sub-analysis of patients with different visual acuities between cylinder and dial confirmed these results with slightly different thresholds: the probability to choose dial technic was for BAD_D, p = 0.03; when BAD_D is > 7.55, PPV = 90%, and for ISV, p = 0.0084; when ISV is > 71, PPV = 88.5%. CONCLUSION: Refraction method is linked to topographic indices ISV and BAD_D. A BAD_D > 7.55 indicates the dial method. In addition to keratoconus screening and diagnosis, this study suggests a new application of the topographer to select a suitable refraction method for eyeglass prescription. TRIAL REGISTRATION: Study registered on the ClinicalTrials.gov database under n°: NCT04174209.
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