Efficacy of Voriconazole Corneal Intrastromal Injection for the Treatment of Fungal Keratitis

Fungal Keratitis: Diagnosis, Management, and Recent Advances

Fungal keratitis is one of the major causes of microbial keratitis that may lead to corneal blindness. Many problems related to diagnosis and therapy are encountered in fungal keratitis, including difficulty in obtaining laboratory diagnoses and the availability and efficacy of antifungal medications. Intensive and prolonged use of antifungal topical preparations may not be enough. The use of antifungal medications is considered the main treatment for fungal keratitis. It is recommended to start antifungal therapy after confirmation of the clinical diagnosis with a smear or positive cultures. Topical application of antifungal medications is a mainstay for the treatment of fungal keratitis; however, systemic, intra-stromal, or intra-cameral routes may be used. Therapeutic keratoplasty is the main surgical procedure approved for the management of fungal keratitis with good success rate. Intrastromal corneal injection of antifungal medications may result in steady-state drug levels within the corneal tissue and prevent intervals of decreased antifungal drug concentration below its therapeutic level. In cases of severe fungal keratitis with deep stromal infiltration not responding to treatment, intracameral injection of antifungal agents may be effective. Collagen cross-linking has been proposed to be beneficial for cases of fungal keratitis as a stand-alone therapy or as an adjunct to antifungal medications. Although collagen cross-linking has been extensively studied in the past few years, its protocol still needs many modifications to optimize UV fluence levels, irradiation time, and concentration of riboflavin to achieve 100% microbial killing.

Toxicity of simultaneous intrastromal and intracameral injection of voriconazole on corneal endothelium in a rabbit model

PURPOSE

To investigate the toxicity of repeated simultaneous intrastromal and intracameral injections of voriconazole in corneal endothelial cells in a rabbit model.

METHODS

Thirty-six eyes of 18 New Zealand white rabbits (six eyes per group) were divided into 6 groups according to the concentration of voriconazole (Group A, 0%; Group B, 0.05%; Group C, 0.1%; Group D, 0.25%; Group E, 0.5%; Group F, 1%). A combination of intrastromal and intracameral voriconazole injections were administrated to the eyes of each group three times on days 0, 3, and 7. Corneal clouding grades and central corneal thickness (CCT) were examined on days 0, 3, 7, 10, and 14. The endothelial cell counts (ECC) were measured on days 0 and 14. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed on day 14.

RESULTS

Group F (1%) showed more severe corneal clouding than the other groups (Groups A-E) from day 7 (p < 0.05, respectively). There were no significant differences in CCT and ECC among the six groups at any time point (p > 0.05, respectively). SEM revealed blurring of the cell border and loss of microvilli at concentrations ≥0.25% (Groups D-F). TEM revealed microstructural changes in endothelial cells at concentrations ≥0.1% (Groups C-F), and multiple vacuoles were observed at a concentration of 1% voriconazole (Group F).

CONCLUSIONS

Repeated simultaneous intrastromal and intracameral voriconazole injections at a concentration of 0.1% or higher induced microstructural endothelial damage in rabbit corneal endothelial cells.

Natamycin versus natamycin combined with voriconazole in the treatment of fungal keratitis

Objective

To observe the therapeutic effect of natamycin combined with voriconazole in the treatment of fungal keratitis (FK).

Methods

This is a retrospective study. The subjects of this study were 64 patients with FK who were admitted to Baoding No.1 Central Hospital from February 2019 to July 2022. The enrolled patients were divided into control group (n= 32) and study group (n= 32) by the random number table method. The control group was treated with natamycin alone, and the study group was treated with natamycin combined with voriconazole. The total efficacy, time of disappearance of ocular symptoms, visual acuity level, keratitis severity score, corneal ulcer area, tear fungus index and incidence of adverse reactions were compared between the two groups.

Results

The total efficacy,of the study group was significantly higher than that of the control group. The disappearance time of corneal ulcer, photophobia, foreign body sensation and hypopyon in the study group was shorter than those in the control group. Keratitis severity score and (1,3)-β-D-glucan level in the study group were lower than those in the control group. The corneal ulcer area was narrowed in the study group than that of the control group, and the visual acuity level in the former group was higher than that of the latter group. Besides, there was no significant difference in the frequency of adverse reactions between the two groups.

Conclusion

Natamycin combined with voriconazole is safe and effective in the treatment of FK.

Continuous voriconazole lavage in managing moderate and severe fungal keratitis: a randomized controlled trial

PURPOSE

To assess the effectiveness and safety of continuous lavage with 1% voriconazole (CL) for moderate and severe fungal keratitis.

METHODS

Thirty-one patients were randomized to receive topical eye drops either alone (T) or combined with continuous 1% voriconazole lavage (CL-T). The primary outcome was the cure rate at 3 months. The secondary outcomes were the 6-day efficacy, 3-day infiltration size and depth, hypopyon height, central corneal thickness (CCT), epithelial defect size, and subject feelings and clinical signs assessment scores.

RESULTS

At 3 months, the cure rate was comparable between the groups in patients with moderate fungal keratitis (66.7% vs. 62.5%, P = 0.60). However, among severe cases, 4 cases (44.4%) in the CL-T group healed successfully, while none in the T group; this difference was not significant (P = 0.08), although it was very close to 0.05. This may be related to the small sample size. After 6 days, the percentage of patients with "worsened" ulcers in the CL-T group was lower than that in the T group (0% vs. 31%, P = 0.043). The infiltration size, infiltration depth, and hypopyon height in the CL-T group were smaller than those in the T group after 3 days (all P < 0.05). There was no difference in CCT, epithelial defect size, subject feelings scores, or clinical signs scores between groups.

CONCLUSION

These outcomes suggest that CL is an effective and safe adjuvant method for controlling the progression of moderate and severe fungal keratitis.

TRIAL REGISTRATION NUMBER

ChiCTR2100050565.