Characteristics of Astigmatism after MyoRing Implantation

Bahram KHOSRAVI, Masoud KHORRAMI-NEJAD, Sattar RAJABI, Mohamad AMIRI, Hesam HASHEMIAN, Mehdi KHODAPARAST

Abstract


Considering the rising number of MyoRing implantation procedures in keratoconic corneas and the refractive outcomes associated with this treatment modality, this study aimed to evaluate and compare the magnitude and axis orientation of total and corneal astigmatism between before and after MyoRing implantation in 34 eyes of 28 patients with keratoconus (KCN) (mean age: 29.41 ± 7.0 years). The inclusion criterion was a reliable diagnosis of clinical KCN based on corneal biomicroscopic and tomographic findings. The mean total astigmatism of ocular refraction decreased significantly from -4.27 ± 3.15 D (before MyoRing implantation) to -2.18 ± 1.63 D (after MyoRing implantation) (P < 0.001). The mean astigmatism in the anterior and posterior surface of the cornea decreased significantly by 1.16 D (P = 0.001) and 0.24 D (P = 0.009), respectively, after MyoRing implantation. Before MyoRing implantation, the axis orientation of total ocular astigmatism for with-the-rule, oblique, and against-the-rule astigmatism was 21%, 42%, and 37%, respectively; at 6 months after MyoRing implantation, it was 18%, 24%, and 58%, respectively. Before MyoRing implantation, the axis orientation for with-the-rule, against-the-rule, and oblique astigmatism of the anterior surface of the cornea was 59%, 24%, and 17%, respectively; at 6 months after MyoRing implantation, it was 52%, 24%, and 24%, respectively. Before MyoRing implantation, the axis orientation of with-the-rule, oblique, and against-the-rule astigmatism of the posterior surface of the cornea was 68%, 29%, and 3%, respectively; at 6 months after MyoRing implantation, it was 67%, 12%, and 12%, respectively. MyoRing implantation significantly decreased the amount of total, anterior, and posterior corneal astigmatism.


References


Rabinowitz YS. Keratoconus. Surv Ophthalmol. 1998;42(4):297-319. doi: 10.1016/s0039-6257(97)001 19-7

Norouzpour A, Mehdizadeh A. A novel insight into keratoconus: mechanical fatigue of the cornea. Med Hypothesis Discov Innov Ophthalmol. 2012;1(1):14-7. pmid: 24600612

Vazirani J, Basu S. Keratoconus: current perspectives. Clin Ophthalmol. 2013;7:2019-30. doi: 10.2147/OPTH .S50119 pmid: 24143069

Smolek MK, Beekhuis WH. Collagen fibril orientation in the human corneal stroma and its implications in keratoconus. Invest Ophthalmol Vis Sci. 1997;38(7):1289-90. pmid: 9191590

Li X, Rabinowitz YS, Rasheed K, Yang H. Longitudinal study of the normal eyes in unilateral keratoconus patients. Ophthalmology. 2004;111(3):440-6. doi: 10.1016/j.ophtha.2003.06.020 pmid: 15019316

Marsack JD, Parker KE, Applegate RA. Performance of wavefront-guided soft lenses in three keratoconus subjects. Optom Vis Sci. 2008;85(12):E1172-8. doi: 10.1097/OPX.0b013e31818e8eaa pmid: 19050464

Reeves SW, Stinnett S, Adelman RA, Afshari NA. Risk factors for progression to penetrating keratoplasty in patients with keratoconus. Am J Ophthalmol. 2005;140(4):607-11. doi: 10.1016/j.ajo.2005.05.029 pmid: 16226512

Lim L, Pesudovs K, Coster DJ. Penetrating keratoplasty for keratoconus: visual outcome and success. Ophthalmology. 2000;107(6):1125-31. pmid: 108578 32

T AI, Elmor O. Intracorneal Rings (INTACS SK) Might be Beneficial in Keratoconus; A Prospective Nonrandomized Study. Med Hypothesis Discov Innov Ophthalmol. 2013;2(2):35-40. pmid: 24600640

Jabbarvand M, Salamatrad A, Hashemian H, Mazloumi M, Khodaparast M. Continuous intracorneal ring implantation for keratoconus using a femtosecond laser. J Cataract Refract Surg. 2013;39(7):1081-7. doi: 10.1016/j.jcrs.2013.02.054 pmid: 23706931

Jadidi K, Nejat F, Mosavi SA, Naderi M, Katiraee A, Janani L, et al. Full-ring Intrastromal Corneal Implantation for Correcting High Myopia in Patients with Severe Keratoconus. Med Hypothesis Discov Innov Ophthalmol. 2016;5(3):89-95. pmid: 28293654

Alio JL, Vega-Estrada A, Esperanza S, Barraquer RI, Teus MA, Murta J. Intrastromal corneal ring segments: how successful is the surgical treatment of keratoconus? Middle East Afr J Ophthalmol. 2014;21(1):3-9. doi: 10.4103/0974-9233.124076 pmid: 24669139

Pinero DP, Alio JL, El Kady B, Coskunseven E, Morbelli H, Uceda-Montanes A, et al. Refractive and aberrometric outcomes of intracorneal ring segments for keratoconus: mechanical versus femtosecond-assisted procedures. Ophthalmology. 2009;116(9):1675-87. doi: 10.1016/j.ophtha.2009.05 .016 pmid: 19643498

Shabayek MH, Alio JL. Intrastromal corneal ring segment implantation by femtosecond laser for keratoconus correction. Ophthalmology. 2007;114(9):1643-52. doi: 10.1016/j.ophtha.2006.11. 033 pmid: 17400293

Alio JL, Pinero DP, Daxer A. Clinical outcomes after complete ring implantation in corneal ectasia using the femtosecond technology: a pilot study. Ophthalmology. 2011;118(7):1282-90. doi: 10.1016/ j.ophtha.2010.12.012 pmid: 21440940

Chatzis N, Hafezi F. Progression of keratoconus and efficacy of pediatric [corrected] corneal collagen cross-linking in children and adolescents. J Refract Surg. 2012;28(11):753-8. doi: 10.3928/1081597X-20121011 -01 pmid: 23347367

Koch DD, Ali SF, Weikert MP, Shirayama M, Jenkins R, Wang L. Contribution of posterior corneal astigmatism to total corneal astigmatism. J Cataract Refract Surg. 2012;38(12):2080-7. doi: 10.1016/j.jcrs.2012.08.036 pmid: 23069271

Kamiya K, Shimizu K, Igarashi A, Miyake T. Assessment of Anterior, Posterior, and Total Central Corneal Astigmatism in Eyes With Keratoconus. Am J Ophthalmol. 2015;160(5):851-7 e1. doi: 10.1016/j.ajo. 2015.08.016 pmid: 26299537

Aslani F, Khorrami-Nejad M, Aghazadeh Amiri M, Hashemian H, Askarizadeh F, Khosravi B. Characteristics of Posterior Corneal Astigmatism in Different Stages of Keratoconus. J Ophthalmic Vis Res. 2018;13(1):3-9. doi: 10.4103/jovr.jovr_217_16 pmid: 29403582


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