http://www.ncbi.nlm.nih.gov/entrez/quer ... uery_hl=13

Cornea. 2005 Jan;24(1):92-102. Related Articles, Links


Pathologic findings in postmortem corneas after successful laser in situ keratomileusis.

Kramer TR, Chuckpaiwong V, Dawson DG, L'Hernault N, Grossniklaus HE, Edelhauser HF.

Emory Eye Center, Emory University, Atlanta, GA 30322, USA. Theresa_Kramer@emoryhealthcare.org

PURPOSE: To examine the histologic and ultrastructural features of human corneas after successful laser in situ keratomileusis (LASIK).

METHODS: Corneas from 48 eyes of 25 postmortem patients were processed for histology and transmission electron microscopy (TEM). The 25 patients had LASIK between 3 months and 7 years prior to death. Evaluation of all 5 layers of the cornea and the LASIK flap interface region was done using routine histology, periodic acid-Schiff (PAS)-stained specimens, toluidine blue-stained thick sections, and TEM.

RESULTS: In patients for whom visual acuity was known, the first postoperative day uncorrected visual acuity was 20/15 to 20/30. In patients for whom clinical records were available, the postoperative corneal topography was normal and clinical examination showed a semicircular ring of haze at the wound margin of the LASIK flap. Histologically, the LASIK flap measured, on average, 142.7 microm (range, 100-200). A spectrum of abnormal histopathologic and ultrastructural findings was present in all corneas. Findings at the flap surface included elongated basal epithelial cells, epithelial hyperplasia, thickening and undulations of the epithelial basement membrane (EBM), and undulations of Bowman's layer. Findings in or adjacent to the wound included collagen lamellar disarray; activated keratocytes; quiescent keratocytes with small vacuoles; epithelial ingrowth; eosinophilic deposits; PAS-positive, electron-dense granular material interspersed with randomly ordered collagen fibrils; increased spacing between collagen fibrils; and widely spaced banded collagen. There was no observable correlation between postoperative intervals and the severity or type of pathologic change except for the accumulation the electron-dense granular material.

CONCLUSIONS: Permanent pathologic changes were present in all post-LASIK corneas. These changes were most prevalent in the lamellar interface wound. These changes along with other pathologic alterations in post-LASIK corneas may change the functionality of the cornea after LASIK.

To understand the extent of the damage, you really should get the full-text of this article.

http://www.ncbi.nlm.nih.gov/entrez/quer ... uery_hl=16

1: Ophthalmology. 2005 Apr;112(4):634-44.

Ex vivo confocal microscopy of human LASIK corneas with histologic and ultrastructural correlation.

Dawson DG, Holley GP, Geroski DH, Waring GO 3rd, Grossniklaus HE, Edelhauser HF.

Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, USA.

OBJECTIVE: To perform confocal microscopy on postmortem human LASIK corneas and correlate these findings to histologic and ultrastructure evaluations.

DESIGN: Prospective, consecutive, observational case series.

PARTICIPANTS: Ninety postmortem LASIK corneas (47 patients) were evaluated for histopathology, of which 22 consecutive corneas (12 patients) were also evaluated by confocal microscopy. Six normal corneas (3 patients) served as controls.

METHODS: This observational case series involving 22 corneas from 12 patients with postoperative intervals from 1 month to 6.5 years after LASIK surgery were collected. The corneas were mounted in an artificial anterior chamber and perfused with balanced salt solution before confocal microscopy was performed on the center of the cornea. The corneas were then bisected and processed for light and transmission electron microscopy.

RESULTS: Confocal microscopy, along with histologic and ultrastructural correlations, demonstrated that the most prevalent alterations in the centers of LASIK corneas were a slightly thickened epithelium caused by focal basal epithelial cell hypertrophic modifications, random undulations in Bowman's layer over the flap surface, and a variably thick hypocellular primitive stromal interface scar. By using confocal microscopy, the interface wound was easily identified in 100% of the cases because numerous brightly reflective interface particles were always present in the hypocellular primitive stromal scar. These particles were found primarily to consist of organic cellular constituents, some of which were transient in nature.

CONCLUSION: After LASIK, active stromal wound healing in the central cornea results in the production of a hypocellular primitive stromal scar, whereas secondary tissue adjustments seem to cause the Bowman's layer undulations and the subsequent epithelial cell modifications. Most of the interface particles revealed by confocal microscopy in the region of the stromal scar are organic in nature and presumably innocuous to the cornea.