Infectious keratitis may occur after surface ablation procedures or LASIK, as both types of surgery involve disturbance of the ocular surface (Fig 6-5). As a result, eyelid preparation and proper draping are recommended. The risk of infection varies depending on the specific technique, with surface ablation more commonly at risk of postoperative infection compared to LASIK. The most common etiologic agents for these infections are gram-positive organisms, including Staphylococcus aureus, methicillin-resistant Staphylococcus aureus(MRSA),Streptococcus pneumoniae, and Streptococcus viridans. Although health care workers and others exposed in hospital and nursing home settings may be at greatest risk for MRSA infection, MRSA infections have been diagnosed in increasing numbers of cases without known risk factors. Atypical mycobacteria, Nocardia asteroides, and fungi have also been reported to cause infectious keratitis after surface ablation and LASIK.
PRK and other surface ablation techniques involve creation of an iatrogenic corneal epithelial defect that may take 3–5 days to heal. During this time, the risk of postoperative infectious keratitis is greatest because of exposure of the stroma, use of a bandage contact lens, and administration of topical corticosteroid drops, all of which increase the opportunity for eyelid and conjunctival bacterial flora to gain access to the stroma. Treatment of postoperative infectious keratitis consists of culture and sensitivity testing of contact lens and corneal scrapings and institution of appropriate intensive, topical, broad-spectrum antibiotic coverage, being cognizant of the higher prevalence of keratitis secondary to gram-positive organisms. Treatment may require a combination of antimicrobial agents. Fungal keratitis can also occur, especially with concomitant corticosteroid use. With that in mind, cultures should include fungal assays, and treatment for keratitis should include antifungal agents in suspected cases (see BCSC Section 8, External Disease and Cornea).
Figure 6-5 Infectious keratitis 1 month postoperatively after LASIK.
(Courtesy of M. Bowes Hamill, MD.)
Figure 6-6 Infectious keratitis in a LASIK flap after recurrent epithelial abrasion.
(Courtesy of Jayne S. Weiss, MD.)
During or shortly after LASIK, which involves creation of a corneal flap, eyelid and conjunctival flora may enter and remain sequestered under the flap. The antimicrobial components in the tears and in topically applied antibiotic drops have difficulty penetrating into the deep stroma to reach the organisms (Fig 6-6). If a post-LASIK infection is suspected, the surgeon can lift the flap, scrape the stromal bed for culture and sensitivity testing, and irrigate with antibiotics prior to flap repositioning. Intensive treatment with topical antibiotic drops, as described previously, can be started pending culture results. If there is lack of clinical progress, additional scrapings and irrigation may be necessary, the flap may be amputated, and the antibiotic regimen may be altered.
Llovet F, de Rojas V, Interlandi E, et al. Infectious keratitis in 204,586 LASIK procedures. Ophthalmology. 2010;117(3):232–238.
Mozayan A, Madu A, Channa P. Laser in-situ keratomileusis infection: review and update of current practices. Curr Opin Ophthalmol. 2011;22(4):233–237.
Solomon R, Donnenfeld ED, Perry HD, et al. Methicillin-resistant Staphylococcus aureus infectious keratitis following refractive surgery. Am J Ophthalmol. 2007;143(4):629–634.
Wroblewski KJ, Pasternak JF, Bower KS, et al. Infectious keratitis after photorefractive keratectomy in the United States Army and Navy. Ophthalmology. 2006;113(4):520–525.
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.