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Management of Postoperative Complications
VISION REHABILITATION FOR CORNEAS WITH BUTTONHOLE
A buttonholed flap occurs when the microkeratome blade travels more superficially than intended and enters the epithelium/Bowman’s complex. Buttonholes may be partial thickness if they transect the Bowman’s layer or full thickness if they exit through the epithelium. The incidence of buttonholes ranges between 0.2% and 0.56%.1 This is the most common complication in microkeratome LASIK, resulting in the loss of best-corrected visual acuity (BCVA). Risk factors include the following:
- High keratometric values.
- Previous incisional keratotomy.
- Pre-existing surface lesion (eg, pterygiums, corneal scars).
Management
While some recommend proceeding with scraping the epithelium and performing a photorefractive keratectomy (PRK)/LASIK laser ablation (Figures 15-1 and 15-2), this approach may not be feasible in high myopic patients due to the appearance of subepithelial haze.
Figure 15-1. Epithelial flap lifting after alcohol application for 40s.
Figure 15-2. Successful excimer laser treatment. At the patient’s 2-month follow-up visit, his uncorrected distance visual acuity was 20/20. No epithelial ingrowth was observed.
Using a no-touch transepithelial PRK within 2 weeks may prevent irregular astigmatism formation from the uneven ablation profile resulting from any late scar formation.
Video: 0 minutes 5 seconds; LASIK 3 months over buttonhole.
Figure 15-3. Identifying and lifting the flap edge carefully to avoid flap tear due to underlying scarring or melting.
EPITHELIAL INGROWTH
Implantation of epithelial cells in the interface may be due to seeding during surgery or migration under the flap. Most of these cells will disappear without consequences. More concerning is epithelial ingrowth that is contiguous with the flap edge. This can progress to involve the visual axis with irregular astigmatism and possible flap melting. Epithelial growth at the interface may be more common after enhancement procedures due to adjacent epithelial abrasions with increased cell proliferation.
Management
Nonprogressive epithelial ingrowth should be monitored. Hyperopic shift is an early indicator of possible underlying stromal melt. This may result in loss of BCVA. Epithelial cells under the LASIK flap should be managed aggressively if they progress toward the visual axis or if they induce stromal melting. The flap is lifted, the stromal bed and the flap undersurface are thoroughly irrigated and scraped, and the flap is repositioned (Figures 15-3, 15-4, 15-5, and 15-6). Epithelial cell debridement can be achieved mechanically with a #15 blade or with dedicated instruments (eg, Yaghouti LASIK Polisher [ASICO]), or by using excimer laser bursts in phototherapeutic keratectomy mode.
Video: 0 minutes 58 seconds
Figure 15-4. Scrape the bed with a blade and/or a LASIK flap lifter.
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