**5. Recent advances in surgical treatment**

Surgical intervention may be an option for patients with refractory FK not responding to medical treatment and severe fungal infections. Penetrating keratoplasty is considered the most common surgical intervention for serious fungal keratitis and cases with perforation or impending perforation. Recent advances have added more options such as targeted drug delivery at the site of infection in the form of intrastromal injections, collagen cross-linking and rose Bengal aided photodynamic therapy.

#### **5.1 Intrastromal voriconazole**

The efficacy of topical, as well as systemic, voriconazole is well established. Intra stromal voriconazole has been found as an effective approach for targeted drug delivery in the management of deep FK not responding to standard topical therapy [95–97]. Targeted drug delivery overcomes the issue of poor bioavailability of drugs in cases of deep fungal keratitis. It provides a depot of drug, close to the infected area. However, risk of introducing a new infection, inadvertent anterior chamber entry while performing the procedure in a hazy cornea are associated.

#### **5.2 Intracameral amphotericin B**

Intracameral Amphotericin B is another approach for targeted drug delivery, indicated when medical treatment with topical and systemic antifungal has failed, especially in cases with deep mycosis, endothelial plaque and presence of hypopyon with inflammation of the anterior chamber. The concentration injected, ranges between 5 and 10 μg/0.1 ml [98, 99].

#### **5.3 Penetrating Keratoplasty**

Penetrating Keratoplasty (PK) is indicated for treatment of refractory or severe fungal keratitis, corneal thinning and perforation in FK [100]. A retrospective study including 52 eyes which underwent PK for corneal perforations secondary to FK, reported improved visual acuity in 46 eyes (88.5%) and clear grafts in 44 eyes (84.6%) at final follow-up [101]. The common complications of PK are graft rejection, recurrence of infection, and secondary glaucoma. Following PK, oral and topical antifungal medications are usually continued for 2 weeks and if pathology reports presence of fungus on the margin of the cornea sample, treatment continues for 6–8 weeks.

Cyclosporine has been recommended after PK in cases of fungal keratitis as it has been suggested to have dual antifungal and anti-immune properties [102]. However; evidences at present are limited, further studies are required to evaluate the risk and benefit of cyclosporine patients undergoing corneal transplant for fungal keratitis.
