Infectious keratitis is one of the dreaded events after refractive surgery, with a reported incidence of 0.03% to 0.2% after laser in situ keratomileusis (LASIK) and surface ablation procedures.1,2 Small-incision lenticule extraction (SMILE, Carl Zeiss Meditec AG) is the latest advancement in the field of refractive surgery, which entails the creation of a stromal lenticule that is subsequently removed to offer a myopic correction. Bilateral infectious bacterial keratitis and unilateral sterile keratitis have been reported after small-incision lenticule extraction.3,4 To our knowledge, no cases of demonstrated fungal keratitis after small-incision lenticule extraction have been reported. Herein, we report a case of unilateral fungal keratitis and discuss the subsequent management.
A 20-year-old woman presented to the refractive services at the Centre for Sight, New Delhi, India, seeking correction for myopic astigmatism of −2.50 −1.50 × 20 in the right eye and −2.0 −1.0 × 155 in the left eye. Her medical history was unremarkable with no risk factors for infection and no history of diabetes or previous contact lens wear. An ocular evaluation did not reveal clinical signs of periocular pathology such as blepharitis or dacryocystitis. Corneal tomography (Pentacam, Oculus Optikgeräte GmbH) was within normal limits, with a minimum corneal thickness of 547 μm and 553 μm in the right eye and left eye, respectively.
Small-incision lenticule extraction was performed using a femtosecond-laser system (Visumax, Carl Zeiss Meditec AG). Preoperative preparation included lid cleaning with povidone–iodine 0.5% and topical administration of povidone–iodine 0.1%. Separate sets of surgical sheets, lid speculums, and surgical instruments were used for each patient. The surgery was reported as uneventful.
The postoperative treatment regimen included moxifloxacin 0.5% ophthalmic solution 4 times a day, loteprednol etabonate 0.5% in tapered doses, and polyethylene glycol and propylene glycol 0.3% 6 times a day.
On postoperative day 1, the patient reported defective vision, intense pain, and photophobia in the right eye. Her uncorrected distance visual acuity (UDVA) was 20/40 in the right eye and 20/20 in the left eye. A slitlamp evaluation of the right eye revealed focal paracentral infiltrates involving the interface (Figure 1). Because the infiltrative material was insufficient to perform a scraping, an empirical treatment with topical fortified vancomycin 5% and fortified tobramycin 1.4% eyedrops was started on an hourly basis, and topical steroid administration was withdrawn. However, the clinical condition worsened over a subsequent few days and a dense infiltrate involving the cap was noted on postoperative day 4, with a decline in the UDVA to 20/200 (Figure 2). The left eye demonstrated a clear interface. Corneal scraping was performed and the infiltrate was sent for microscopic examination and culture inoculation. A potassium hydroxide mount revealed septate fungal filaments. At this juncture, antibiotics were withdrawn and topical voriconazole 1% and natamycin 5% were initiated on an hourly basis, along with cycloplegic drops (homatropine hydrobromide) twice a day.
Three days later, culture reports from the interface scraping showed significant growth of Aspergillus species. An interface wash with an antifungal solution (voriconazole 1%) was performed daily over the next 5 days.
On subsequent visits, the patient demonstrated clinical improvement and the corneal infiltrate showed progressive resolution. At the 3-month postoperative visit, her UDVA improved to 20/60 in the right eye. Her corrected distance visual acuity was 20/45 with an astigmatic correction of −1.0 × 10. A slitlamp evaluation revealed a central fibrotic stromal scar, with no evidence of active keratitis (Figure 3). A dense scar at the corneal interface was demonstrated on anterior segment optical coherence tomography (Figure 4). The left eye maintained a UDVA of 20/20.
Infectious keratitis is a potentially sight-threatening event after refractive surgery. Various organisms have been identified in post-LASIK infective keratitis, with gram-positive bacteria responsible for early onset infection, whereas atypical mycobacteria and fungi are more commonly implicated in late-onset disease.5 Predisposing factors include excessive surgical manipulation, breaks in the epithelial barrier or delayed postoperative reepithelialization, and intraoperative contamination.6 Creating an interface in small-incision lenticule extraction might introduce the microorganisms directly into the stroma, and an associated epithelial defect that serves as a portal for infection might not be necessary. In addition, contaminated irrigating fluids used for interface wash during small-incision lenticule extraction could cause direct stromal inoculation. Because no proven additional benefit of interface wash has been established, it could be avoided.
Ivarsen et al.7 demonstrated the incidence of complications in more than 1500 eyes after small-incision lenticule extraction, and reported 5 cases of culture-negative interface infiltrates that healed without scarring. Another study8 reported 1 case of infectious infiltrate in a cohort of 246 eyes, with subsequent response to topical antibiotics and interface irrigation. Photoactivated chromophore for infectious keratitis–crosslinking has also been described for the treatment of corneal infiltrates, with greater success in bacterial keratitis.9 The subsequent use was demonstrated for the treatment of a culture-proven Staphylococcus infiltrate noted in the anterior cap after small-incision lenticule extraction.10 The procedure helped limit the spread of the infiltrate to the cap-stromal interface, precluding the need for an interface irrigation.
A high degree of suspicion coupled with rapid diagnosis and prompt therapy is required. The management of infectious keratitis after small-incision lenticule extraction can be challenging because performing an adequate scraping might be difficult in deep-seated infiltrates. The penetration of antibiotics into the deeper stromal layers and anterior chamber is adequate. The same, however, is untrue for antifungals, which demonstrate a poor penetration into the deeper corneal layers. The small-incision lenticule extraction interface provides a unique opportunity for antifungals to be directly administered into the interface, leading to a prompt response to therapy and eventual resolution with scarring.
To our knowledge, we described the first reported case of fungal keratitis after small-incision lenticule extraction. Our case demonstrated a deep-seated infiltrate involving the interface, requiring scraping for microbiological investigation and subsequent interface irrigation. This allowed greater antifungal penetration and removal of the sequestered nidus of infection. In addition, a closer follow-up is imperative because of the aggressive clinical presentation with fungal keratitis. The earlier studies demonstrate a delayed onset of fungal infiltrates usually 2 weeks after surgery. In contrast, our patient presented with an early infiltrate. A high degree of clinical suspicion, especially in tropical countries with a higher incidence of fungal keratitis in comparison to western literature, is necessary and corticosteroid administration should be withheld until microbiological diagnosis is established.11
In conclusion, although infection after keratorefractive procedures are rare, they might result in significant visual loss. A high suspicion of fungal keratitis should be present, even for cases with early presentation and eyes refractory to broad spectrum antibiotic therapy. Prompt interface scraping for microbiological analysis and subsequent irrigation could limit disease severity and significant visual loss.
None of the authors has a financial or proprietary interest in any material or method mentioned.
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