To compare the effect of mechanical and alcohol-assisted excision on the histological ultrastructure of epithelial disks from human corneas. Vardinoyiannion Eye Institute of Crete, University of Crete, Medical School, Crete, Greece. Ten eyes of 10 patients were deepithelialized by 1 of 2 two techniques. In 6 eyes, a customized instrument was used to mechanically separate the epithelial layer. In 4 eyes, the epithelial disks were obtained using the conventional laser-assisted subepithelial keratectomy (LASEK) technique; that is, with alcohol concentrations of 15% and 20%. All specimens were assessed by light and electron microscopy, and the histological findings of the 2 methods were compared. Transmission electron microscopy showed that when the epithelial disks were excised by mechanical separation, the lamina densa and lamina lucida were preserved and the hemidesmosomes had normal morphology along almost the entire length of the basement membrane. The basal epithelial cells of the separated epithelial disks showed minimal trauma and edema. Specimens obtained using 15% and 20% alcohol concentrations showed formation of cytoplasmic fragments of the basal epithelial cells, enlargement of the intercellular spaces, and extensive discontinuities in the basement membrane, which was excised at the level of the lamina lucida. Mechanical separation did not affect the normal cell morphology of the excised epithelial disks. Transmission electron microscopy of the specimens proved the manual technique is less invasive to epithelial integrity than LASEK using either alcohol concentration.

No abstract

The reports of an increasing incidence of iatrogenic ectasia, the evolution of wavefront aberrometry, and the suggestion that the laser in situ keratomileusis flap could lead to unpredictable biomechanical corneal changes have renewed interest in surface ablation and have set the stage for the introduction of alternative photorefractive treatment modalities. The theoretical advantage of surface procedures, such as laser epithelial keratomileusis that preserve the epithelial button, stems from the repositioning of the epithelial flap over the laser-ablated corneal surface. This epithelial sheet is thought to act as a natural contact lens that decreases postoperative pain and haze formation. Epipolis laser in situ keratomileusis is an alternative modality of epithelial separation with the use of a device that features a blunt oscillating blade. This surgical approach does not require the use of alcohol for epithelial loosening.

Preliminary clinical results suggest that epi-LASIK is a safe and efficient method for the correction of low myopia. Further studies will establish this method as an alternative surface ablation procedure.

To prospectively study the effects of the use of Intacs microthin prescription inserts (Addition Technology Inc, Fremont, Calif) for the postoperative management of corneal ectasia resulting from laser in situ keratomileusis (LASIK). Methods: In this prospective nonrandomized clinical trial, 10 eyes of 7 patients with post-LASIK corneal ectasia (2 men and 5 women) aged 33 to 46 years (mean±SD, 40.67 ± 5.99 years) were included. The follow-up ranged from 6 to 24 months (mean±SD, 15.0±6.5 months). Two Intacs segments of thickness depending on the residual refraction of the patients were inserted in each eye. Main Outcome Measures: Uncorrected visual acuity, best spectacle-corrected visual acuity, refractive outcome, and topographic findings after Intacs implantation. Results: Intacs were successfully implanted in all eyes. Spherical equivalent error was statistically significantly reduced after Intacs implantation (pre-Intacs, mean±SD: −4.81±3.24 Diopters (D) (range, −13.75 to −2.50 D) to −0.96±2.93 D (range, −8.75 to 2.50 D) (PϽ.001). Pre-Intacs uncorrected visual acuity was 20/100 or worse in all eyes (range, counting fingers to 20/100) while at the last follow-up examination, 9 (90%) of 10 eyes had uncorrected visual acuity of 20/40 or better (range, counting fingers to 20/20). Three eyes maintained the pre-Intacs best spectacle-corrected visual acuity while the rest of the eyes (7) experienced a gain of 1 to 2 lines. The mean difference between pre-Intacs and last follow-up best spectacle-corrected visual acuity was a gain of 1.00±0.82 lines. Conclusions: Intracorneal ring segments implantation improved uncorrected visual acuity and best spectaclecorrected visual acuity in patients with post-LASIK ectasia. Even though the results are encouraging, concern still exists regarding the long-term effect of such an approach for the management of post-LASIK ectasia.