Intracorneal rings for keratoconus and keratectasia

Ertan, Aylin; Colin, Joseph

doi:10.1016/j.jcrs.2007.02.048

Cited by 171 publications

(137 citation statements)

References 76 publications

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“…1,2 FDA-approved 3 intrastromal corneal ring segments (ICRS) have been found beneficial for the treatment of KC and corneal ectasia following refractive surgery [4][5][6] as they flatten and regularize the cornea by means of an arc shortening effect. 7 The most common types of ICRS used in clinical practice are Intacs (Addition Technology, Inc., Sunnyvale, CA, USA) and Ferrara rings (Ferrara Ophthalmics, Brazil).…”

Section: Introductionmentioning

confidence: 99%

Depth evaluation of intended vs actual intacs intrastromal ring segments using optical coherence tomography

Barbara

Naftali

2015

Eye

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Purpose Evaluation of actual vs intended intrastromal corneal ring segments (ICRS) implantation depth as measured by anterior segment optical coherence tomography (OCT) Methods Prospective study evaluating 30 Intacs segments implanted manually in 19 eyes of 15 patients suffering from keratoconus. Segment depth evaluation was performed using anterior segment OCT. Measurements were performed above and below the segment at 3 points in relation to the incision site. Statistical analysis was performed using the SAS software for ANOVA, matched t-test, and GLIMMIX procedure. Results Intacs segment depth was 153-μm shallower than intended (58% vs 80%). Segment layout demonstrated the proximal and distal portions to be 13-μm shallower and 12-μm deeper (on average), respectively. Intacs segment thickness does not influence implantation depth. Intacs segments implanted in the same eye do not share similar implantation depths. Stromal compression is likely to occur. Conclusion Intacs are implanted at a shallower depth than intended. The 'pocketing' stage prior to implantation most likely has a stronger effect on the segment's final implantation depth than does the incisions' depth.

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Section: Introductionmentioning

confidence: 99%

Depth evaluation of intended vs actual intacs intrastromal ring segments using optical coherence tomography

Barbara

Naftali

2015

Eye

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“…Treatment options include conservative approaches, aimed at maintaining visual acuity, such as rigid contact lenses placed to straighten corneal aberrations (33). Alternatively, more invasive methods are applied using intrastromal corneal implants (34) or performing anterior lamellar keratoplasty or penetrating keratoplasty in extreme cases (35,36). However, all of these techniques only correct the refractive errors of keratoconus and do not treat the cause underlying the corneal ectasia and therefore do not stop the progression of keratoconus.…”

mentioning

confidence: 99%

Effects of Ultraviolet-A and Riboflavin on the Interaction of Collagen and Proteoglycans during Corneal Cross-linking

Zhang

Conrad

2011

Journal of Biological Chemistry

158

112

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Corneal cross-linking using riboflavin and ultraviolet-A (RFUVA) is a clinical treatment targeting the stroma in progressive keratoconus. The stroma contains keratocan, lumican, mimecan, and decorin, core proteins of major proteoglycans (PGs) that bind collagen fibrils, playing important roles in stromal transparency. Here, a model reaction system using purified, non-glycosylated PG core proteins in solution in vitro has been compared with reactions inside an intact cornea, ex vivo, revealing effects of RFUVA on interactions between PGs and collagen cross-linking. Irradiation with UVA and riboflavin cross-links collagen ␣ and ␤ chains into larger polymers. In addition, RFUVA cross-links PG core proteins, forming higher molecular weight polymers. When collagen type I is mixed with individual purified, non-glycosylated PG core proteins in solution in vitro and subjected to RFUVA, both keratocan and lumican strongly inhibit collagen cross-linking. However, mimecan and decorin do not inhibit but instead form cross-links with collagen, forming new high molecular weight polymers. In contrast, corneal glycosaminoglycans, keratan sulfate and chondroitin sulfate, in isolation from their core proteins, are not cross-linked by RFUVA and do not form cross-links with collagen. Significantly, when RFUVA is conducted on intact corneas ex vivo, both keratocan and lumican, in their natively glycosylated form, do form cross-links with collagen. Thus, RFUVA causes cross-linking of collagen molecules among themselves and PG core proteins among themselves, together with limited linkages between collagen and keratocan, lumican, mimecan, and decorin. RFUVA as a diagnostic tool reveals that keratocan and lumican core proteins interact with collagen very differently than do mimecan and decorin.The cornea is the transparent, dome-shaped tissue covering the front of the eye. It is a powerful refracting surface, providing 65-75% of the eye's focusing power, and is made up of three distinct layers: epithelium, stroma, and endothelium. The stroma comprises about 90% of cornea thickness in humans (1).Although it is very highly innervated, it does not contain any blood vessels (2-4). Collagen gives the cornea its strength, elasticity, and form (5). The unique molecular shape, paracrystalline arrangement, and very regular fine diameter of the evenly spaced collagen fibrils are essential in producing a transparent cornea (6, 7).In the corneal stromal extracellular matrix, glycosaminoglycan (GAG) 2 polysaccharides are the most abundant negatively charged macromolecules and are classified on the basis of their repeating disaccharide structures into four main groups: keratan sulfate (KS), chondroitin sulfate/dermatan sulfate (CS/DS), heparan sulfate and heparin, and hyaluronan. Glycosaminoglycans, normally covalently attached to proteoglycan (PG) core proteins, play important roles in corneal transparency, nerve growth cone guidance, and cell adhesion, largely dependent on their patterns of sulfation or lack of it (8, 9). The corneal stroma is comp...

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“…Keratokonus tedavi edilebilir bir hastalık olup erken evrelerde teşhis edildiğinde kornea nakline gidilmeden tedavisi mümkün olmaktadır [1][2][3][4]. Hem cerrahi, hem de cerrahi olmayan tedavi yöntemleri başarıyla uygulanmaktadır.…”

Section: şEkil 1 Normal Ve Keratokonuslu Kornea Görüntüleri (Views Ounclassified

GÖRÜNTÜ BÖLÜTLEME ve GÖRÜNTÜ BENZETİMİ YÖNTEMLERİ YARDIMI ile HASTALIĞIN TEŞHİS ve TEDAVİ SONRASI SÜREÇLERİNİN DESTEKLENMESİ: KERATOKONUS ÖRNEĞİ

Kaya¹,

Çavuşoğlu²,

Çakmak³

et al. 2016

Gazi Üniversitesi Mühendislik-Mimarlık Fakültesi Dergisi

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Intracorneal rings for keratoconus and keratectasia

Cited by 171 publications

References 76 publications

Depth evaluation of intended vs actual intacs intrastromal ring segments using optical coherence tomography

Depth evaluation of intended vs actual intacs intrastromal ring segments using optical coherence tomography

Effects of Ultraviolet-A and Riboflavin on the Interaction of Collagen and Proteoglycans during Corneal Cross-linking

GÖRÜNTÜ BÖLÜTLEME ve GÖRÜNTÜ BENZETİMİ YÖNTEMLERİ YARDIMI ile HASTALIĞIN TEŞHİS ve TEDAVİ SONRASI SÜREÇLERİNİN DESTEKLENMESİ: KERATOKONUS ÖRNEĞİ

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