Interface infectious keratitis following deep anterior lamellar keratoplasty.

A 32-year-old female patient underwent deep anterior lamellar keratoplasty (DALK) in both eyes for advanced keratoconus. She developed an infiltrate in the nasal paracentral interface of the left eye. In view of the paracentral location, localized epithelial removal/stromal scraping was done and the infiltrate was removed using forceps and sent for microbiological assay, which revealed fungal filaments. The patient successfully responded to intensive topical antifungal therapy with the maintenance of visual acuity. Interface keratitis following DALK frequently needs graft lift/interface wash due to deep location, rapid spread and poor penetration and efficacy of topical medications. In view of a paracentral location, modified debulking with topical therapy resulted in a satisfactory outcome in our case thereby avoiding the need for more invasive treatments.

Infectious keratitis at the interface between the donor graft and the host Descemet's membrane (DM) following deep anterior lamellar keratoplasty (DALK) is a rare occurrence. The most common cause is reported to be Candida species.[1] Interface keratitis responds poorly to topical medications and, hence, requires surgical intervention.

We report a case of interface infectious keratitis following DALK that successfully responded to modified debulking and medical treatment.

Case Report

A 32-year-old female patient presented to our hospital on January 23, 2015, with clinical features of bilateral advanced keratoconus (KC) with central corneal haze. Her best-corrected visual acuity (BCVA) in the right eye (RE) was 6/40 (Snellen chart) N24 with a correction of − 20.75 DS/−6.00 DC at 10° and in the left eye (LE) was 6/15 N12 with a correction of −20.00 DS/−6.00 DC at 180° [Fig. 1a and b].

Figure 1

(a) Scheimpflug imaging showing advanced keratoconus in the right eye; (b) left eye

In view of advanced KC with central haze, very thin central corneal thickness (340 microns), and very steep sagittal curvatures (>65D), DALK was advised to the patient in both eyes, RE first. The patient underwent DALK in both eyes; on February 13, 2015, in RE and March 09, 2015, in LE. Surgery was uneventful in both eyes. Big bubble technique was used to obtain complete DM baring and interrupted sutures were used to fix the graft. On May 6, 2015, the patient presented for follow-up. She had a BCVA of 6/9 in the RE (3 months postoperative) and 6/12 in LE (2 months postoperative). The LE showed a dense infiltrate in the nasal paracentral interface [Fig. 2]. The patient was empirically started on topical moxifloxacin and topical voriconazole 2 hourly along with topical homatropine eye drops three times/day to LE. Topical steroids were discontinued. The patient was reviewed after 5 days. BCVA was maintained at 6/15. In view of the absence of worsening, deep location of the infiltrate and maintaining vision, topical medications were continued, and the patient was asked to review after 3 weeks.

Figure 2

Dense interface Infiltrate at 2 months postoperative left eye

After 3 weeks (89th day), the patient returned for follow-up with reduced visual acuity in her LE (counting fingers 1 m) with dense infiltrate measuring 1 mm × 1 mm, extending anteriorly toward superficial stroma and posteriorly toward the anterior chamber with the appearance of a streak hypopyon [Fig. 3].

Figure 3

Progressive infiltrate at 3 months postoperative

The options at this stage were:

Interface wash with removal of infiltrate for microbiological assay: This has an attendant risk of DM perforation and spread of infection

Scraping of the epithelium and stroma over the infiltrate with the removal of the fluffy mass.

We followed the second technique using a capsulorhexis forceps. Staining was positive for fungal filaments; culture revealed no growth for either fungus or bacteria.

The patient was additionally prescribed topical natamycin eye drops 1 hourly along with systemic itraconazole 100 mg twice a day for 7 days.

The patient started responding to treatment and infiltrate started to resolve by the 95th day. Visual acuity improved to 6/60 [Fig. 4].

Figure 4

Infiltrate responding to treatment following debulking

By the 106th day, visual acuity had improved to 6/24 with the presence of a macular-leucomatous scar at the site of resolution of infiltrate. Topical antifungal medication was reduced to six times/day. Topical loteprednol eye drops were started at a minimal dosage of three times/day [Fig. 5].

Figure 5

Resolving infiltrate with beginning scar formation

By the 119th day (4 months), visual acuity was 6/18 with no signs of infection. A leucomatous scar was present at the site of infiltrate [Fig. 6a and b].

Figure 6

Resolved infiltrate with leucomatous scar: (a) Diffuse illumination; (b) slit section

Discussion

Interface keratitis between the donor and host corneas following lamellar keratoplasty is a rare complication. In a retrospective review of 135 patients who had undergone anterior lamellar keratoplasty (ALK), Sharma et al. found that interface microbial keratitis developed postoperatively in 3 out of 15 cases.[2]

The most common causative pathogens identified were Candida species although the Herpes simplex virus and both Gram-positive and Gram-negative bacteria have been isolated.[13] The time from surgery to presentation varies considerably. Infectious keratitis can present as early as 2 days following uncomplicated surgery (Klebsiella pneumoniae) and as late as 2.5 months postoperatively.[4]

On the basis of the above reports, in our case, we had started the patient on topical voriconazole and moxifloxacin at initial presentation of the interface infiltrate.

Clinically, interface keratitis presents as white or creamy deposits at the host–donor interface in the center or periphery of the donor lenticule. A majority of cases show little inflammation presumably because of prior topical steroid use. These cases often have an aggressive clinical course and are often unresponsive to topical and oral antibiotic therapy. Microbiological diagnosis of the infectious organism is obtained from cultures of the material collected from the interface, donor scleral rims, or the removed infected donor lenticule.[3]

In a report of nine cases of interface keratitis following lamellar keratoplasty, Sharma et al. found that 55.5% of cases failed medical therapy and required therapeutic penetrating keratoplasty.[2] Fontana et al. describe removing the lamellar graft in a case of Candida albicans-related interface keratitis, irrigating the recipient bed with amphotericin B, and attaching a new lamellar graft. This was unsuccessful in controlling the keratitis, and 2 weeks later, penetrating keratoplasty was necessary. Penetrating keratoplasty has also been reported as the definitive treatment by others.[1]

In our case, in view of the paracentral infiltrate, we could obtain material from the deep-seated infiltrate using forceps under topical anesthesia after the removal of epithelium over the infiltrate. This enabled an etiologic diagnosis and successful management. This also averted a possible need for surgical intervention, i.e., graft lift and interface wash (which carries a significant risk of DM perforation/conversion to penetrating keratoplasty) while maintaining an acceptable level of BCVA.

In view of the shorter duration of topical steroids in DALK, the spread of infection without symptoms may be averted. Furthermore, in our case, since the steroids were already on a tapering dosage (twice daily), the patient became symptomatic and was already on frequent follow-ups, thereby enabling early detection and treatment.

Conclusion

Interface infectious keratitis is a potentially serious complication following DALK. In view of deep-seated infection, silent spread, nonresponse to topical medications, and difficulty to obtain microbiological samples, it usually requires surgical intervention. If it is present in a paracentral location, localized removal of epithelium and removal of infiltrate using a forceps may serve to obtain microbiological samples/debulk the infectious load, thereby permitting continued topical medication and successful resolution of infection. Furthermore, in our case, we were able to restart topical steroids and limit the extent of scar to a paracentral location (no further treatment of the scar was deemed necessary), thus maintaining an acceptable level of final BCVA despite the induced astigmatism.

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Conflicts of interest

There are no conflicts of interest.