The structure and swelling of corneal scar tissue in penetrating full-thickness wounds.
OBJECTIVE
The purpose of this study was to determine corneal thickness and to examine the collagen and proteoglycans in full-thickness corneal scars up to 16 months following wounding.


METHODS
Ultrasound pachymetry was used to measure the depths of penetrating central scars and their surrounding areas in 16 rabbit corneas. Measurements were taken at regular intervals: 5, 10, 12, and 16 months after healing. Transmission electron microscopy was then used to study the stroma of the resulting scars to observe the collagen organization and the amount, as well as the size, of cuprolinic blue-stained proteoglycan filaments within the stroma. Furthermore, ex vivo swelling of selected wounded contralateral excised corneas was undertaken by the measured addition of distilled water.


RESULTS
In vivo, the thickness of the scar tissue was significantly less than that of the surrounding tissue throughout the period studied. By 12 months the proteoglycan filaments within the scar were of a similar size and number to those within the adjacent tissue, whereas the collagen fibrils within the scar were still disorganized (collagen interweaving, lack of a lamellar structure). Once excised and allowed to swell in water, scar tissue thickness remained relatively unchanged, whereas the surrounding tissue swelled considerably.


CONCLUSIONS
Disorganized fibril arrangement inhibits the normal swelling of the scar tissue, which remains reduced. Furthermore, even after many months of healing, collagen remodeling in corneal scar tissue is not complete.
Connon
Che J
CJ
Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kawaramachi kamigyo-ku, Kyoto 602-0841, Japan. connoncj@cf.ac.uk
Meek
Keith M
KM
D000818:Animals; D002921:Cicatrix / Q000378:metabolism / Q000473:pathology*; D003094:Collagen / Q000502:physiology / Q000648:ultrastructure; D003315:Cornea / Q000648:ultrastructure; D015715:Corneal Edema / Q000378:metabolism / Q000473:pathology*; D065306:Corneal Injuries; D003319:Corneal Stroma / Q000378:metabolism / Q000648:ultrastructure; D015807:Eye Injuries, Penetrating / Q000378:metabolism / Q000473:pathology*; D024022:Fibrillar Collagens / Q000648:ultrastructure; D007211:Indoles; D009942:Organometallic Compounds; D011509:Proteoglycans / Q000502:physiology / Q000648:ultrastructure; D011817:Rabbits; D014945:Wound Healing
D024022:Fibrillar Collagens; D007211:Indoles; D009942:Organometallic Compounds; D011509:Proteoglycans; C015445:copper phthalocyanine; D003094:Collagen