Histopathological findings after intracorneal ring segment implantation in keratoconic human corneas.
OBJECTIVE
To evaluate histopathological changes induced in keratoconic corneas after implantation of Intacs intracorneal ring segments (Addition Technology, Inc.).


METHODS
Departments of Ophthalmology and Pathology, Hospital Pellegrin, Bordeaux, France.


METHODS
This retrospective study included 8 keratoconic, contact-lens-intolerant eyes of 8 patients who had penetrating keratoplasty (PKP) after removal of Intacs inserts because of a poor refractive outcome or insert extrusion. Light microscopy was performed on all specimens after conventional staining. Immunohistochemistry was performed to identify cell types located next to the tunnel using AE1/AE3 cytokeratins, CD34, vimentin, collagen IV, and alpha-smooth muscle actin monoclonal antibodies.


RESULTS
Conventional histology showed hypoplasia of the epithelium immediately surrounding the channel. There was no evidence of an inflammatory response or foreign-body granuloma. Keratocyte density was decreased above and below the tunnel, and collagen IV synthesis was seen in the scar area. All samples stained negatively with alpha-smooth muscle actin, indicating that myofibroblasts were not present. These changes were no longer visible when PKP was performed more than 6 months after Intacs explantation.


CONCLUSIONS
Intacs induced keratocyte apoptosis, probably through a switch to a collagenous synthetic phenotype. Although histological changes seem to be entirely reversible after implant removal, longer follow-up is necessary to determine whether they accelerate corneal thinning and keratoconus progression via apoptosis and release of metalloprotease.
Samimi
Sépideh
S
Ophthalmology and Pathology Departments, Hospital Pellegrin, Bordeaux, France.
Leger
François
F
Touboul
David
D
Colin
Joseph
J
D000199:Actins / Q000378:metabolism; D000328:Adult; D018952:Antigens, CD34 / Q000378:metabolism; D017209:Apoptosis; D024141:Collagen Type IV / Q000378:metabolism; D003319:Corneal Stroma / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D020878:Device Removal; D018450:Disease Progression; D005260:Female; D005347:Fibroblasts / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000378:metabolism; D007640:Keratoconus / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D015948:Keratoplasty, Penetrating; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D012189:Retrospective Studies; D014746:Vimentin / Q000378:metabolism
D000199:Actins; D018952:Antigens, CD34; D024141:Collagen Type IV; D014746:Vimentin; D007633:Keratins