{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,4]],"date-time":"2026-05-04T10:37:47Z","timestamp":1777891067825,"version":"3.51.4"},"reference-count":24,"publisher":"SAGE Publications","issue":"4","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["THC"],"published-print":{"date-parts":[[2021,7,9]]},"abstract":"<jats:p>OBJECTIVE: This is a case study on the application of a piggy-back lens in the correction of severe keratoconus. METHODS: From the results of general eye examination, refractive state examination, and corneal morphology examination on the patient, it was determined that corneal protrusion and deformation of the right eye were obvious. The right eye was corrected using a piggy-back lens and the left eye with a rigid gas-permeable contact lens (RGPCL) alone. RESULTS: The right-eye lens fit well and the lens coverage was good. Both the static and dynamic fit results for the left-eye lens were good. After wearing the glasses for one month, the patient attended a review and stated that the lenses were comfortable to wear. The patient\u2019s vision was good after wearing the lenses. No obvious congestion was found in the conjunctiva under a slit lamp. The effects on both eyes of wearing RGPCLs were favorable. The corneal curvature reduced and the corneal thickness only changed to a small degree. CONCLUSION: For keratoconus patients, application of a piggy-back lens can improve corrected visual acuity, comfort levels, and safety, prolong the wearing time, and enhance the effect of orthokeratology.<\/jats:p>","DOI":"10.3233\/thc-212889","type":"journal-article","created":{"date-parts":[[2021,4,6]],"date-time":"2021-04-06T13:07:57Z","timestamp":1617714477000},"page":"813-822","source":"Crossref","is-referenced-by-count":1,"title":["Application of piggy-back lens in the correction of severe keratoconus: A case study"],"prefix":"10.1177","volume":"29","author":[{"given":"Fang-Fang","family":"Lan","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lu","family":"Gan","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"179","reference":[{"key":"10.3233\/THC-212889_ref1","doi-asserted-by":"crossref","first-page":"435","DOI":"10.4103\/0301-4738.116070","article-title":"Management of pediatric keratoconus \u2013 evolving role of corneal collagen cross-linking: an update","volume":"61","author":"Kankariya","year":"2013","journal-title":"Indian J Ophthalmol."},{"key":"10.3233\/THC-212889_ref2","doi-asserted-by":"crossref","first-page":"297","DOI":"10.1016\/S0039-6257(97)00119-7","article-title":"Keratoconus","volume":"42","author":"Rabinowitz","year":"1998","journal-title":"Surv Ophthalmol."},{"key":"10.3233\/THC-212889_ref3","doi-asserted-by":"crossref","first-page":"257927","DOI":"10.1155\/2015\/257927","article-title":"An update on the safety and efficacy of corneal collagen cross-linking in pediatric keratoconus","volume":"2015","author":"El Rami","year":"2015","journal-title":"Biomed Res Int."},{"key":"10.3233\/THC-212889_ref4","doi-asserted-by":"crossref","first-page":"796","DOI":"10.1016\/j.jcrs.2007.12.039","article-title":"Collagen crosslinking with riboflavin and ultraviolet-A light in keratoconus: long-term results","volume":"34","author":"Raiskup-Wolf","year":"2008","journal-title":"J Cataract Refract Surg."},{"key":"10.3233\/THC-212889_ref5","doi-asserted-by":"crossref","first-page":"2257","DOI":"10.1007\/s10792-017-0699-8","article-title":"Pediatric keratoconus: a review of the literature","volume":"38","author":"Mukhtar","year":"2018","journal-title":"Int Ophthalmol."},{"key":"10.3233\/THC-212889_ref6","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1111\/cxo.12047","article-title":"Recent advances in corneal transplantation for keratoconus","volume":"96","author":"Cassidy","year":"2013","journal-title":"Clin Exp Optom."},{"key":"10.3233\/THC-212889_ref7","doi-asserted-by":"crossref","first-page":"398","DOI":"10.1016\/S0886-3350(97)80184-8","article-title":"Corneal transplant for keratoconus: results in early and late disease","volume":"23","author":"Buzard","year":"1997","journal-title":"J Cataract Refract Surg."},{"key":"10.3233\/THC-212889_ref8","doi-asserted-by":"crossref","first-page":"691","DOI":"10.1001\/archophthalmol.2011.7","article-title":"Corneal transplantation for keratoconus: a registry study","volume":"129","author":"Kelly","year":"2011","journal-title":"Arch Ophthalmol."},{"key":"10.3233\/THC-212889_ref9","doi-asserted-by":"crossref","first-page":"342","DOI":"10.1016\/0002-9394(82)90537-2","article-title":"Epikeratophakia for the treatment of keratoconus","volume":"93","author":"Kaufman","year":"1982","journal-title":"Am J Ophthalmol."},{"key":"10.3233\/THC-212889_ref10","doi-asserted-by":"crossref","first-page":"1294","DOI":"10.1001\/archopht.1986.01050210048024","article-title":"Epikeratophakia for keratoconus. The nationwide study","volume":"104","author":"McDonald","year":"1986","journal-title":"Arch Ophthalmol."},{"key":"10.3233\/THC-212889_ref11","doi-asserted-by":"crossref","first-page":"18","DOI":"10.4103\/0301-4738.105049","article-title":"Anatomical and functional graft survival, 10 years after epikeratoplasty in keratoconus","volume":"61","author":"Panda","year":"2013","journal-title":"Indian J Ophthalmol."},{"key":"10.3233\/THC-212889_ref12","doi-asserted-by":"crossref","first-page":"456","DOI":"10.1016\/S0886-3350(98)80284-8","article-title":"Live-epikeratophakia for keratoconus","volume":"24","author":"Krumeich","year":"1998","journal-title":"J Cataract Refract Surg."},{"key":"10.3233\/THC-212889_ref13","doi-asserted-by":"crossref","first-page":"620","DOI":"10.1016\/S0002-9394(02)02220-1","article-title":"Riboflavin\/ultraviolet-a-induced collagen crosslinking for the treatment of keratoconus","volume":"135","author":"Wollensak","year":"2003","journal-title":"Am J Ophthalmol."},{"key":"10.3233\/THC-212889_ref14","first-page":"184","article-title":"Corneal collagen cross-linking in the stabilization of keratoconus","volume":"116","author":"Maier","year":"2019","journal-title":"Dtsch Arztebl Int."},{"key":"10.3233\/THC-212889_ref15","doi-asserted-by":"crossref","first-page":"8145651","DOI":"10.1155\/2017\/8145651","article-title":"Corneal collagen cross-linking for keratoconus: systematic review","volume":"2017","author":"Kobashi","year":"2017","journal-title":"Biomed Res Int."},{"key":"10.3233\/THC-212889_ref16","doi-asserted-by":"crossref","first-page":"196","DOI":"10.1016\/S1542-0124(12)70166-0","article-title":"Excimer laser phototherapeutic keratectomy","volume":"4","author":"Ayres","year":"2006","journal-title":"Ocul Surf."},{"key":"10.3233\/THC-212889_ref17","doi-asserted-by":"crossref","first-page":"144","DOI":"10.1097\/ICO.0b013e31818526b8","article-title":"Excimer laser phototherapeutic keratectomy for keratoconus nodules","volume":"28","author":"Elsahn","year":"2009","journal-title":"Cornea."},{"key":"10.3233\/THC-212889_ref18","doi-asserted-by":"crossref","first-page":"79","DOI":"10.1016\/j.survophthal.2019.07.002","article-title":"Phototherapeutic keratectomy","volume":"65","author":"Nagpal","year":"2020","journal-title":"Surv Ophthalmol."},{"key":"10.3233\/THC-212889_ref19","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1186\/s40662-016-0040-z","article-title":"The use of intracorneal ring segments in keratoconus","volume":"3","author":"Vega-Estrada","year":"2016","journal-title":"Eye Vis (Lond)."},{"key":"10.3233\/THC-212889_ref20","doi-asserted-by":"crossref","first-page":"1886","DOI":"10.1016\/j.jcrs.2007.06.055","article-title":"Intracorneal ring segment implantation for the management of keratoconus: safety and efficacy","volume":"33","author":"Zare","year":"2007","journal-title":"J Cataract Refract Surg."},{"key":"10.3233\/THC-212889_ref21","doi-asserted-by":"crossref","first-page":"220","DOI":"10.1097\/ICU.0000000000000582","article-title":"Effectiveness of intracorneal ring segments for keratoconus","volume":"30","author":"Park","year":"2019","journal-title":"Curr Opin Ophthalmol."},{"key":"10.3233\/THC-212889_ref22","doi-asserted-by":"crossref","first-page":"214","DOI":"10.1097\/01.ico.0000178276.90892.ac","article-title":"Oxygen transmissibility of piggyback systems with conventional soft and silicone hydrogel contact lenses","volume":"25","author":"L\u00f3pez-Alemany","year":"2006","journal-title":"Cornea."},{"key":"10.3233\/THC-212889_ref23","first-page":"1","article-title":"Piggy-back fitting post-intaes insertion for keratoconus","volume":"4","author":"Scheid","year":"2005","journal-title":"J Silicone Hydrogels."},{"key":"10.3233\/THC-212889_ref24","first-page":"1161","article-title":"Critical oxygen levels to avoid corneal edema for daily and extended wear contact lenses","volume":"25","author":"Holden","year":"1984","journal-title":"Invest Ophthalmol Vis Sci."}],"container-title":["Technology and Health Care"],"original-title":[],"link":[{"URL":"https:\/\/content.iospress.com\/download?id=10.3233\/THC-212889","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T05:53:17Z","timestamp":1777614797000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.sagepub.com\/doi\/full\/10.3233\/THC-212889"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,7,9]]},"references-count":24,"journal-issue":{"issue":"4"},"URL":"https:\/\/doi.org\/10.3233\/thc-212889","relation":{},"ISSN":["0928-7329","1878-7401"],"issn-type":[{"value":"0928-7329","type":"print"},{"value":"1878-7401","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,7,9]]}}}