Treatment of duck-phenotype keratoconus using asymmetric intrastromal corneal ring-segments with hybrid technique
DOI:
https://doi.org/10.70313/2718.7446.v18.n1.398Keywords:
keratoconus, cornea, corneal topography, corneal diseases, corneal pachimetryAbstract
Objective: To evaluate the safety and efficacy of using asymmetric intrastromal corneal ring-segments (ICRS) for the treatment of duck-phenotype keratoconus through an hybrid technique.
Methods: A retrospective study was performed in a private clinic of Cordoba City (Argentina), evaluating patients with duck-phenotype keratoconus, implanted with one segment of Keraring AS6 (Mediphacos, Belo Horizonte, Brazil). Uncorrected distance visual acuity (UDVA), manifest refractive spherical equivalent (MRSE), manifest refractive astigmatism, and topographic parameters were evaluated before and six months after the procedure.
Results: 31 eyes of 27 patients received Keraring AS6 implants, attaining a reduction in median UDVA from 0.7 to 0.3, mean keratometry from 47.39 ± 2.75 D to 45.45 ± 2.97 D, median refractive astigmatism from -5.00 D to -2.50 D and MRSE from -5.25 D to -2.62 D. All effects were statistically significant (p < 0.01).
Conclusions: In the present series, Keraring AS6 implantation by hybrid technique was effective and safe for correcting corneal irregularities secondary to duck-phenotype keratoconus, improving UDVA, MRSE, manifest astigmatism, and topographic parameters.
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References
Rabinowitz YS. Keratoconus. Surv Ophthalmol. 1998; 42(4): 297-319. doi:10.1016/s0039-6257(97)00119-7
Vought R, Greenstein SA, Gelles J, Hersh PS. The pathophysiology of keratoconus. Cornea. 2025; 44(2): 137-143. doi: 10.1097/ICO.0000000000003585.
Albertazzi R, Blanco T. Génesis del queratocono, el “neuromisterio” mejor guardado: una visión neuroquímica y neurodegenerativa. Oftalmol Clin Exp 2020; 13(4): 173-188. doi:10.70313/2718.7446.v13.n4.32
Alfonso JF. Clasificación del queratocono basada en fenotipos clínicos: influencia del astigmatismo congénito en la morfología del queratocono. In: del Buey Sayas A, Peris Martínez C, editors. Biomecánica y arquitectura corneal. Barcelona: Elsevier España, 2014, p. 165-184.
Kang MJ, Byun YS, Yoo YS, Whang WJ, Joo CK. Long-term outcome of intrastromal corneal ring segments in keratoconus: five-year follow up. Sci Rep. 2019; 9(1): 315. doi:10.1038/s41598-018-36668-7
Schanzlin DJ, Asbell PA, Burris TE, Durrie DS. The intrastromal corneal ring segments. Phase II results for the correction of myopia. Ophthalmology. 1997; 104(7): 1067-1078. doi:10.1016/s0161-6420(97)30183-3
Burris TE, Ayer CT, Evensen DA, Davenport JM. Effects of intrastromal corneal ring size and thickness on corneal flattening in human eyes. Refract Corneal Surg. 1991; 7(1): 46-50.
Prisant O, Pottier E, Guedj T, Hoang Xuan T. Clinical outcomes of an asymmetric model of intrastromal corneal ring segments for the correction of keratoconus. Cornea. 2020; 39(2): 155-160. doi:10.1097/ICO.0000000000002160.
Sartori MBF, Kalaf AM, Cruz LI. Assymetric intrastromal corneal ring segments. In: Almodin E, Nassarala BA, Sandes J, editors. Keratoconus: a comprehensive guide to diagnosis and treatment. Cham: Springer Switzerland, 2022, p. 575-585.
Alfonso JF, Lisa C, Merayo-Lloves J, Fernández-Vega Cueto L, Montés-Micó R. Intrastromal corneal ring segment implantation in paracentral keratoconus with coincident topographic and coma axis. J Cataract Refract Surg. 2012; 38(9): 1576-1582. doi:10.1016/j.jcrs.2012.05.031
Alfonso JF, Fernández-Vega Cueto L, Baamonde B, Merayo-Lloves J, Madrid-Costa D, Montés-Micó R. Inferior intrastromal corneal ring segments in paracentral keratoconus with no coincident topographic and coma axis. J Refract Surg. 2013; 29(4): 266-272. doi:10.3928/1081597X-20130318-06
Fernández-Vega Cueto L, Lisa C, Poo-López A, Madrid-Costa D, Merayo-Lloves J, Alfonso JF. Intrastromal corneal ring segment implantation in 409 paracentral keratoconic eyes. Cornea. 2016; 35(11): 1421-1426. doi:10.1097/ICO.0000000000000978.
Fernández-Vega-Cueto L, Lisa C, Alfonso-Bartolozzi B, Madrid-Costa D, Alfonso JF. Intrastromal corneal ring segment implantation in paracentral keratoconus with perpendicular topographic astigmatism and comatic axis. Eur J Ophthalmol. 2021; 31(4): 1540-1545. doi:10.1177/1120672120952346
Coşkunseven E, Ambrósio R Jr, Smorádková A, et al. Visual, refractive and topographic outcomes of progressive thickness intrastromal corneal ring segments for keratoconic eyes. Int Ophthalmol. 2020; 40(11): 2835-2844. doi:10.1007/s10792-020-01467-5. [errata correction: Int Ophthalmol. 2020; 40(11): 2845.]
Coskunseven E, Kayhan B. Clinical, tomographic, and topometric outcomes of progressive thickness intracorneal ring segment implantations in duck-type keratoconus. Indian J Ophthalmol. 2022; 70(8): 2939-2945. doi:10.4103/ijo.IJO_2770_21.
Arbelaez JG, Arbelaez MC. Efficacy of progressive thickness intrastromal corneal ring segments in the treatment of duck phenotype keratoconus. Eur J Ophthalmol. 2021; 31(5): 2191-2199. doi:10.1177/11206721211001722.
Baptista PM, Marques JH, Neves MM, Gomes M, Oliveira L. Asymmetric thickness intracorneal ring segments for keratoconus. Clin Ophthalmol. 2020; 14: 4415-4421. doi:10.2147/OPTH.S283387
Barugel R, David C, Kallel S, et al. Comparative study of asymmetric versus non-asymmetric intrastromal corneal ring segments for the management of keratoconus. J Refract Surg. 2021; 37(8): 552-561. doi:10.3928/1081597X-20210526-01
Vega-Estrada A, Chorro E, Sewelam A, Alio JL. Clinical outcomes of a new asymmetric intracorneal ring segment for the treatment of keratoconus. Cornea. 2019; 38(10): 1228-1232. doi:10.1097/ICO.0000000000002062.
Kammoun H, Piñero DP, Álvarez de Toledo J, Barraquer RI, García de Oteyza G. Clinical outcomes of femtosecond laser-assisted implantation of asymmetric ICRS in keratoconus with no coincidence of topographic and comatic axes. J Refract Surg. 2021; 37(10): 693-699. doi:10.3928/1081597X-20210712-04.
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