**3.7 Intrastromal injections with antibiotic agents in the management of bacterial keratitis**

Khan et al. were the first to study the intrastromal injections of antibiotic agents in the management of recalcitrant bacterial keratitis. It was studied on patients with infectious crystalline keratopathy secondary to *Streptococcus paranguis*, where cefuroxime 250 μL/mL was administered in intrastromal injection. Yet, the patients initially needed to undergo debridement of mucous plaque and epithelium to expose corneal stroma and biofilm. Intrastromal injection of cefuroxime (1 ml) in the lesion and stroma region was injected by hydration technique [22].

In this case, cefuroxime was chosen above other antibiotics, such as vancomycin, not only for its sensitivity and low inhibitory concentration but also because it is less harmful to the ocular surface.

Liang et al. reported another case of resistant bacterial keratitis. About 0.02 mL of tobramycin (0.3%) in a single intrastromal injection was administered with a 30 G needle. After 6 months, the keratitis became dormant, and 5 years later, there was no sign of a recurrence [23].

Pak et al. was the first to explain triple-bacterial keratitis which was caused by penicillin-resistant *S. aureus*, pan-sensitive *Staphylococcus epidermidis*, and Achromobactin species and its treatment with intrastromal antibiotic injection. When topical treatment failed to treat the keratitis, a new strategy was used and 0.2 mL of 0.5% moxifloxacin was administered intrastromally, precisely at the edge of the infiltrate. The study explained that the complete remission of the keratitis was accomplished with the first dose at the initial and the second dose after 2 weeks [24].
