One of the major potential complications of surface ablation is corneal haze. To decrease the chance of post–surface ablation corneal haze, especially for eyes with previous corneal surgery such as PRK, LASIK, PKP, RK, or primary surface ablations for moderate to high treatments or deeper ablation depths, a pledget soaked in mitomycin C (usually 0.02% or 0.2 mg/mL) can be placed on the ablated surface for approximately 12 seconds to 2 minutes at the end of the laser exposure. The concentration and duration of mitomycin C application varies by diagnosis and surgeon preference; however, most surgeons tend toward shorter durations of mitomycin C exposure. Application of mitomycin C for 12 seconds appears to be as efficacious for prophylaxis as prolonged times. Some surgeons reduce the amount of treatment when applying mitomycin C in surface ablation due to reports of potential endothelial cell toxicity. The cornea is then copiously irrigated with balanced salt solution to remove excess mitomycin C. To avoid damage to limbal stem cells, care should be taken not to expose the limbus or conjunctiva to mitomycin C. Confocal microscopy studies of human eyes have shown a reduced keratocyte population and less haze in eyes that received mitomycin C.
Some surgeons apply sterile, chilled, balanced salt solution or a frozen cellulose sponge before and/or after the surface ablation procedure in the belief that cooling reduces pain and haze formation. However, the advantage of this practice has not been substantiated in a controlled study. Care should be taken to not expose the eye to tap water, which may result in infectious contamination.
If the LASEK or epi-LASIK variant has been performed, the surgeon carefully floats and moves the epithelial sheet back into position with balanced salt solution. Antibiotic, corticosteroid, and, sometimes, nonsteroidal anti-inflammatory drugs (NSAIDs) are then placed on the eye, followed by a bandage contact lens. Some NSAIDs and antibiotics can be placed directly on the corneal bed, whereas others should be placed only on the surface of the contact lens, as they have been associated with poor corneal healing. If the patient cannot tolerate a bandage contact lens, a pressure patch may be used. Of note, the American Society of Cataract and Refractive Surgery released a clinical alert on February 14, 2013, discussing the postoperative risks posed by certain medications used topically prior to or during LASIK or PRK. The medications listed in this statement have the potential to cause flap slippage and/or diffuse lamellar keratitis (DLK) following LASIK surgery and poor epithelial healing following PRK.
ASCRS Cornea and Refractive Surgery Clinical Committees. Medication alert for LASIK and PRK. [Eyeworld website.] March 2013. Available at www.eyeworld.org/article-medication-alert-for-lasik-and-prk. Accessed November 5, 2016.
Carones F, Vigo L, Scandola E, Vacchini L. Evaluation of the prophylactic use of mitomycin-C to inhibit haze formation after photorefractive keratectomy. J Cataract Refract Surg. 2002; 28(12):2088–2095.
Lee DH, Chung HS, Jeon YC, Boo SD, Yoon YD, Kim JG. Photorefractive keratectomy with intraoperative mitomycin-C application. J Cataract Refract Surg. 2005;31(12):2293–2298.
Virasch VV, Majmudar PA, Epstein RJ, Vaidya NS, Dennis RF. Reduced application time for prophylactic mitomycin C in photorefractive keratectomy. Ophthalmology. 2010;117(5): 885–889.
After the ablation is completed, the flap is replaced onto the stromal bed. The interface is irrigated until all interface debris is eliminated (which is apparent more readily with oblique than with coaxial illumination). The surface of the flap is gently stroked using a smooth instrument, such as an irrigation cannula or a moistened microsurgical spear sponge, from the hinge, or center, to the periphery. This approach helps to ensure that wrinkles are eliminated and that the flap settles back into its original position, as indicated by realignment of the corneal marks made earlier. The peripheral gutters should be symmetric and even. The physiologic dehydration of the stroma by the endothelial pump will begin to secure the flap in position within several minutes. If a significant epithelial defect or a large, loose sheet of epithelium is present, a bandage contact lens should be put in place. Once the flap is adherent, the eyelid speculum is removed carefully so as not to disturb the flap. Most surgeons place varying combinations of antibiotic, NSAID, and corticosteroid drops on the eye at the conclusion of the procedure. The flap is usually rechecked at the slit lamp before the patient leaves to make sure it has remained in proper alignment. A clear shield or protective goggles are often placed to guard against accidental trauma that could displace the flap. Patients are instructed not to rub or squeeze their eyes.
Lui MM, Silas MA, Fugishima H. Complications of photorefractive keratectomy and laser in situ keratomileusis. J Refract Surg. 2003;19(Suppl 2):S247–S249.
Price FW Jr. LASIK. Focal Points: Clinical Modules for Ophthalmologists. San Francisco: American Academy of Ophthalmology; 2000, module 3.
Schallhorn SC, Amesbury EC, Tanzer DJ. Avoidance, recognition, and management of LASIK complications. Am J Ophthalmol. 2006;141(4):733–739.
Excerpted from BCSC 2020-2021 series: Section 13 - Refractive Surgery. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.