Medical interventions for fungal keratitis

Fungal hyphae growing into anterior chamber from cornea

To evaluate the efficacy of corneal cross-linking (CXL) as adjuvant therapy for the treatment of fungal ulcerative keratitis. Forty-one patients with fungal ulcerative keratitis were recruited and assigned into two randomized controlled groups. These groups were treated with CXL combined with antifungal medications (CXL-M) or antifungal medications alone (M). The ulcers were assessed by slit-lamp biomicroscopy, slit-lamp images, in vivo confocal microscopy (IVCM), and anterior segment optical coherence tomography (AS-OCT). The patients were followed up before surgery/first visit (FV), 1day after surgery, 1 and 2weeks, and 1, 2, 3, 4, 5, and 6months after surgery/FV. In the cured patients, the area of corneal ulcers, the duration of ulcer healing, the time to non-observed fungal hyphae by IVCM, the number of antifungal medications, the frequency of administered medications, and the maximum ulcer depth decreased significantly after CXL (all P < 0.05) compared with the M group. There were no significant differences in either corneal thickness or epithelial thickness of ulcers after healing between 5 and 6months after surgery in the CXL-M group, while these were increased significantly at 6months compared with 5months after FV in the M group (both P < 0.05). In our study, CXL accelerated healing of the fungal ulcers, shortened the treatment duration, and minimized the need for medications and surgery. It appears that CXL is an effective procedure and adjuvant therapy for managing fungal keratitis.

To evaluate the validity of confocal microscopy in estimating curative effect and in directing the treatment for fungal keratitis in the process of antifungal chemotherapy. Fifty-eight patients, who were confirmed fungal infection by confocal microscopy, were selected from 328 patients with fungal keratitis. All patients received routine topical and/or oral antifungal medication, and were examined by confocal microscopy once a week and one week after discontinuation of the treatment. The density of hyphae in the corneal lesion, the configuration of inflammatory cells and keratocyte were recorded. Antifungal chemotherapy was adjusted according to examination results and medicines were changed accordingly. If no hyphae were detected by confocal microscopy, antifungal medication was maintained for one week and then discontinued. All patients were followed up for two months to ensure no relapse of fungal infection. Fifty three patients were cured. The area of corneal lesions began to reduce 7 days after the beginning of antifungal chemotherapy. Confocal microscopy examination revealed that the hypha positive sites and the density of hypha were reduced gradually; inflammatory cells also decreased, the configuration of corneal lesion was transformed from asymmetry to symmetry; and normal keratocytes could be detected gradually. After 14 days of treatment, ulcers healed up in 37 cases and no hyphae and inflammatory cells were found in 23 cases. After 28 days of treatment, all corneal ulcers healed up; hyphae and inflammatory cells were completely disappeared in 31 patients, but a few hyphae still could be found in 22 patients. Antifungal chemotherapy was tapered gradually if no hyphae and inflammatory cells were detected by confocal microscopy. There was no relapse of fungus infection during 2-month follow-up. Infection deteriorated in the other five patients within 7 days, which showed increased density of hypha and inflammatory cells under confocal microscopy examination. All of them were treated with a penetrating keratoplasty to save the eyeball. Confocal microscopy is an ideal method for the evaluation of curative effects of fungal keratitis in the process of antifungal chemotherapy. This is also a valuable objective tool in directing antifungal medication.

Objective To analyze the distribution, diversity, and the sensitivity of common pathogen species to antifungal drugs in fungal keratitis during 2000 - 2006 in Shandong province. Methods Samples from corneal serapings and corneal buttons from keratoplasties were used for fungal culture and identification. The distribution and diversity of the pathogens in different years were analyzed. The sensitivity of some common species to antifungal drugs were tested. Results A total of 898 patients were diagnosed as fungal keratitis, in which 770 (85.7%) were positive in fungal culture. Pathogens in 748 cases caused by fungal infection were identified, of which 547 cases were caused by Fusarium (71.0%). The prevelence of Fusarium from 2000 to 2006 was 75.5%, 72.8%, 71.5%, 75.2%, 76%, 68. 8% and 56.4% respectively. Eighty-four cases were caused by Aspergillus( 10.9% ) , which accounted for 15.1% , 15.2% , 13.1%, 10. 2%, 10. 4% , 8.0% and 6. 9% of the cases from 2000 to 2006, respectively. Seventy-four eases were caused by Alternaria (9. 6% ), the percentage of which during 2000 -2006 was 1. 9%, 3.3%, 3.7%, 6. 6%, 8. 8%, 12. 0 and 29. 7% respectively. In genus Fusarium, 10 species were found and the most common species were Fusarium Solani ( 33. 8% ), Fusarium oxysporum ( 28.2% ) and Fusarium moniliforme( 27.4% ). Six species were identified in genus Aspergillus, with Aspergillus flavus (53.6%) and Aspergillus fumigatus (39.3% ) being the most common species. The geometric mean MICs of amphotericin B, terbinafin, itraconazole, 5-flucytosine and fluconazole against the common species were 0. 647, 0. 714, 1. 624, 15. 108 and 27. 070 μg/ml, respectively. The mean MICs of the above five antifungal drugs against Fusarium were 0. 899, 0. 893, 3.077, 37. 124 and 21. 687 μg/ml, respectively, and for Aspergillus, the mean MICs of these agents were 0.794, 0.591, 0.416, 23.973 and 7.127 μg/ml, respectively; for Alternaria,the MICs were 0. 409,0. 479,0. 433,11. 655 and 7. 104 μg/ml ,respectively. Conclusions Genus Fusarium, Aspergillus and Alternaria were the predominant pathogens in fungal keratitis in Shandong Province. During 2000 -2006, Fusarium was the most common one, followed by Aspergillus. The percentage of Aspergillus decreased annually. The third most common pathogen, Alternaria increased during the period. The geometric mean MICs of amphotericin B and terbinafin against Fusarium were lower than those of itraconazole, 5-flucytosine and fluconazole. The MICs of these five anti-fungal drugs against Aspergillus and Alternatia were lower than those for Fusarium. Key words: Keratitis; Eye infections,fungal; Microbial sensitivity tests

Objective To analyze the pathogen distribution and drug sensitivity test results of the corneal ulcers patients who diagnosed as infectious keatitis. Methods The corneal ulcers of the 91 patients with infectious keratitis treated in the department of ophthalmology in the hospital from February 2014 to October 2015 were collected and the specimen was sent for the fungal and bacteria culture and drug sensitivity test of the pathogens. The culture result of corneal ulcers of the patients with infectious keratitis and the drug susceptibility testing result were summarized. Results Among the 91 patients with infectious keratitis, the fungal keratitis were 57 cases accounted for 62.2%; the bacterial keratitis 33 cases accounted for 36.3%; acanthamoeba keratitis 1 case accounted for 1.1%. Among the 57 patients with fungal keratitis, Fusarium species were 27 cases accounted for 47.4%, Alternaria species 21 cases accounted for 36.8%, No-spore species 6 cases accounted for10.5%. Among the 33 patients with bacterial keratitis, gram positive cocci and gram negative bacilli were the commonest pathogens accounted for 72.7% and 21.2%, respectively. Streptococcus pneumoniae was the main pathogen among the gram positive cocci accounted for42.4%. The results of bacteria drug sensitivity tests showed the Streptococcus had the high susceptibility to Cephalosporins, levofloxacin and ofloxacin which was more than 70%. The susceptibility to vancomycin was 100%. The results of fungal drug sensitivity tests showed the terbinafine had 100% susceptibility to the five fungi, Fusarium had the higher susceptibility to the Fluconazole and ketone which was more than 70%. The lower susceptibility was to the amphotericin and voriconazole which was less than 50%. Alternaria species had the higher susceptibility to the four antifungal drugs (terbinafine ketone amphotericin and voriconazole) which was more than 80%, the lower susceptibility to Fluconazole which was 38.1%. No-spore species had the 100% susceptibility to the four antifungal drugs except for voriconazole. Conclusions Fusarium species is the first pathogen of infectious keatitis, Fusarium is the main pathogen and always take the top spot in fungal keratitis. Streptococcus pneumoniae from gram positive cocci is the major pathogen in bacterial keratitis. The Cephalosporins, levofloxacin and ofloxacin can be the conventional drugs because they have the higher susceptibility to the bacterial keratitis caused by Streptococcus. Terbinafine can be the empirical antifungal drugs. Key words: Fungal keratitis; Bacteria keratitis; Drug resistance; Acanthamoeba keratitis

To determine whether a novel third-generation chelating agent (8 mM disodium EDTA dehydrate and 20 mM 2-amino-2-hydroxymethyl-1, 3-propanediol) would act as an antimicrobial potentiator to enhance in vitro activity of antifungal medications against fungal isolates obtained from horses with mycotic keratitis. Fungal isolates (3 Aspergillus isolates, 5 Fusarium isolates, 1 Penicillium isolate, 1 Cladosporium isolate, and 1 Curvularia isolate) obtained from horses with mycotic keratitis and 2 quality-control strains obtained from the American Type Culture Collection (ATCC; Candida albicans ATCC 90028 and Paecilomyces variotii ATCC 36257). Minimum inhibitory concentrations (MICs) against fungal isolates for 4 antifungal drugs (miconazole, ketoconazole, itraconazole, and natamycin) were compared with MICs against fungal isolates for the combinations of each of the 4 antifungal drugs and the chelating agent. The Clinical and Laboratory Standards Institute microdilution assay method was performed by use of reference-grade antifungal powders against the fungal isolates and quality-control strains of fungi. Values for the MIC at which the antifungal drugs decreased the growth of an organism by 50% (MIC50) and 90% (MIC90) were decreased for the control strains and ophthalmic fungal isolates by 50% to 100% when the drugs were used in combination with the chelating agent at a concentration of up to 540 microg/mL. The chelating agent increased in vitro activity of antifungal drugs against common fungal pathogens isolated from eyes of horses with mycotic keratitis.

Fungal infections are often associated with prolonged hospital stay and high mortality, and are costly to the healthcare system. The incidence of fungal infections has increased in tandem with the growing number of immunocompromised patients in recent years, underlining the need for novel antifungal agents. The 2000s were the most prolific decade for the development of antifungal drugs, with the introduction of newer triazoles (voriconazole, posaconazole) and echinocandins (caspofungin, micafungin, anidulafungin), providing a wider choice of treatment options. These newer antifungal agents, however, are much more expensive, and thus, significantly increase hospital drug expenditure. Relative health returns of these high-cost alternatives need to be determined given that healthcare services have limited resources. Accordingly, this thesis was geared towards deriving critical information to facilitate decision making by the healthcare providers in optimising the use of these high-cost antifungal agents for the prophylaxis and treatment of fungal infections. Three main areas were explored: voriconazole prophylaxis in lung transplant (LTx) recipients, cost-effective use of echinocandins in treating candidaemia and invasive candidiasis (IC) and the potential use of caspofungin eye drops for the treatment of fungal keratitis. Within the context of antifungal prophylaxis in lung transplantation, there is no consensus with respect to the choice of agent and strategy due to the paucity of data. An anonymous web-based survey was conducted to determine antifungal prophylactic practice in LTx centres world-wide. Findings from the survey indicated that voriconazole was the most commonly used agent for both universal and pre-emptive prophylaxis within the first six months post-LTx. A retrospective, single-centre, observational study was then undertaken to investigate the efficacy and safety of voriconazole pre-emptive prophylaxis in 62 LTx recipients. Six months after initiation of voriconazole prophylaxis, the majority (75.8%) had successful eradication of fungal colonisation; one patient developed proven fungal infection. Sixteen (25.8%) had died by 12 months after commencing prophylaxis, half due to Bronchiolitis Obliterans Syndrome. Chronic rejection within the 30 days prior to voriconazole prophylaxis was significantly associated with mortality at the 6-month and 12-month end-points. Ten patients (16.1%) had drug-related hepatotoxicity. The second focus was to determine the cost-effectiveness of echinocandins compared to other antifungal agents in treating candidaemia and IC. Accordingly, pharmacoeconomic comparisons between echinocandins (caspofungin, micafungin, anidulafungin), liposomal amphotericin B (LAmB) and fluconazole in the Australian setting were conducted. The comparisons employed decision analytical models based on treatment pathways derived from published randomised clinical trials, and utilised expert panels from Australia. Analyses were from a hospital perspective and cost inputs were obtained from the latest Australian resources. The robustness of the economic models was evaluated by sensitivity analyses. Hospitalisation was revealed as the major cost driver. Anidulafungin was a cost-effective option compared to fluconazole, with an incremental cost-effectiveness ratio of AU$22,003 per life-year saved. Micafungin was expected to have a total net cost-saving of AU$10,957 per patient over LAmB, whereas it was cost-equivalent to caspofungin, with variation in drug acquisition cost likely to be a critical factor. The final aim was to investigate the potential use of caspofungin eye drops as a novel strategy to treat fungal keratitis, with the intention of improving clinical outcomes and saving costs. The successful use of intrastromal and topical caspofungin 0.5% in combination with voriconazole in a case of refractory atypical Alternaria keratitis in a local institution was reported. The utility of caspofungin eye drops in fungal keratitis, however, remains limited, partly due to the lack of data on penetration into the human eye. A liquid chromatography/mass spectrometry assay was then developed and validated to determine the concentrations of caspofungin in human aqueous humour. An open-label study demonstrated that caspofungin 0.5% eye drops resulted in low penetration into the human eye in the absence of inflammation or corneal abrasion, but were generally well tolerated. The eye drops were shown to be stable for at least 28 days at 4 ± 1oC, affording economical use in clinical practice. This thesis has explored a number of important aspects related to the optimal and cost-efficient use of high-cost antifungal agents. Significantly, the data will facilitate informed decision making by clinical practitioners and healthcare policy makers about the use of these high-cost antifungal agents.

Background Recurrent fungal keratitis after corneal transplantation is a primarily cause of treatment failure. Owing to different recurrence positions and clinical features, to choose the appropriate therapy is relative difficult. Objective This study was to investigate the clinical features, therapy and treating outcome of recurrent fungal keratitis after corneal transplantation. Methods Forty-one patients with recurrent fungal keratitis from 628 patients with fungal keratitis who underwent corneal transplantation at the Shandong Eye Hospital from January 2004 through December 2011 were retrospectively reviewed. The positions of recurrent lesions, managements and outcomes were analyzed. Results The positions of recurrent keratitis included transplantation bed, anterior chamber and vitreous in the 41 patients. The fungal infection relapsed in 28 patients (7.12%) undergone penetrating keratoplasty (PKP) and 13 patients (5.53%) undergone lamellar keratoplasty (LKP), without significant difference between them (χ2=0.61, P>0.05). Thirty-six patients were cured, with the overall cure rate 87.80%. Among the 11 recurrence cases on the edge of recipient bed, 3 patients were cured by drug therapy, and other 8 patients were cured by surgery, including lesion resection and/or conjunctival flap cover for 6 patients with lesion >2 mm and secondary PKP for 2 patients with lesion≤2 mm. Four patients with recurrence lesion under the graft following LKP were treated by the reoperation PKP. The different managements were performed in 5 recurrent patients in anterior chamber, including intrachamber injection of drug for 2 patients, anterior chamber lavage for 2 patients and PKP again in 1 patient. Multiple-site recurrent lesions were seen in 12 patients, and the lesions were cured by drug therapy, lesion resection or conjunctival flap cover in 5 patients and by PKP again in 7 patients. In 9 patients with vitreous recurrence, only 4 patients were cured by anti-fungal drug, and ocular evisceration were performed in other 5 patients. Conclusions The clinical features and locations of recurrent fungal keratitis are key basis for the delection of therapeutic regimens. Based on different clinical features, most of the fungal keratitis recurrence after corneal transplantion can be cured. Drug therapy is preferred for the recurrence lesion on recipient bed, and intrachamber drug injection is preferred for recurrence in anterior chamber. For the patients with vitreous recurrence, vitrectomy combined with intravitreal drug should be performed as early as possible. Key words: Cornea; Infection/recurrent, therapy; Fungus; Keratoplasty; Retrospective

Background Fungal keratitis has poor prognosis and high blinding rate, so it is vital to identify the risk factors that affect the treating outcome and prognosis of fungal keratitis. Objective This study was to evaluate the clinical outcome of fungal keratitis and identify the affecting factors. Methods This was a series cases-observational study.A total of 267 eyes of 267 patients with fungal keratitis were included in Henan Eye Institute during January 2013 to January 2014.Eye examinations were performed including slit-lamp microscope examination, corneal smears, confocal microscopy, fungal culture and identification.Combined anti-fungal drugs were topically used in all eyes for the initial treatment then the treating regimen were selected based on the susceptibility testing.corneal lesion resection combined with conjunctival flap transplantation, lamellar corneal transplantation or penetrating corneal transplantation was performed respectively on the patients with poor curative effect after drug treatment.The clinical prognosis of the patients was graded and the affecting factors for clinical outcome were evaluated.This study protocol complied with Helsinki Declaration and was approved by Ethic Committee of Henan Eye Hospital.Written informed consent was obtained from patients or guardians. Results One hundred and eighty-five eyes were cured by anti-fungal eye drops with the effective rate of 69.29%, and the inflammation was controlled in 60 eyes who received combination procedure of anti-fungal drugs with different surgeries, while 22 eyes lost visual function because of refractory glaucoma and final evisceration.The total clinical effective rate was 91.76%.Aspergillus and Fusarium spp. appeared to be the most common pathogenic fungi by drug sensitivity test.The keratitis caused by Aspergillus had lowest cure rate among different fungi (χ2=11.350, P=0.002) and the most poor clinical prognosis (H=31.285, P=0.013). The medication curative rate was 71.8% in the patients with positive culture outcome, which was higher than 62.5% in the patients with negative culture outcome (χ2=8.75, P<0.01). A significant difference was found in the medication curative rate and prognosis between the patients with ≥2 kinds of sensitive anti-fungal drugs and the patients with <2 kinds of sensitive anti-fungal drugs (77.5% versus 52.3%, χ2=9.63, P<0.01; H=24.281, P=0.021). Size of infiltration area, with or without hypopyon, number of sensitive drugs, and pathogenic fungi were significantly correlated with clinical outcome(all at P<0.05). Conclusions In vitro susceptibility testing can guide clinical drug treatment of fungal keratitis.Infiltration area >16 mm2, hypopyon >2 mm, resistance to those drugs in vitro and infection of Fusarium.spp or Aspergillus.spp are predictors of a poor outcome. Key words: Eye infections, fungal/therapy; Keratitis, fungal, Treatment outcome; Risk factors; Human

Fungal keratitis is one of major blindness disease in corneal infection. At present, mistake and missed diagnosis were often happened in Fungal keratitis. Initial doctor was insufficient knowledge of diagnosis. There were not to do etiology examination in corneal fungal infection, and lead to some case getting worse during medicinal treated. Highly ratio patients need controlled infection by corneal transplantation due to severe lack antifungal eye drops, and poor understood the way of antifungal medicine in clinic. Finally, Fungal keratitis is still one of major intractable disease in corneal infection, because some doctor were short of experience to hold surgical opportunity and indication, and corneal donor severe shortage in China.

Objective: To assess the impact of the pre-diagnostic use of corticosteroid on the prognosis of visual outcomes and treatment methods of fungal keratitis. Methods: This was a retrospective consecutive case cohort study. Two hundred and eleven eyes of 211 patients diagnosed with fungal keratitis from December 2014 to December 2015 in Shandong Eye Hospital were analyzed. Thirty-six eyes of 36 patients with a history of corticosteroid use before the diagnosis was the corticosteroid group. The remaining 175 eyes of 175 patients with no use of corticosteroid before or during the treatment was the control group. Patients' demographics, clinical findings, management details, changes after the antifungal therapy, and corrected distance visual acuity 2 months after the cure were recorded. Independent samples t test and chi-square test were used for statistical analysis. Results: The demographic data were matched between the two groups. The fungal onset time of the corticosteroid group was 14.5±10.1 days, which was significantly shorter than that of the control group, 20.6±22.5 days (t=2.657, P=0.008). The mean diameter of corneal lesions was 6.3±2.4 mm in the corticosteroid group, which was significantly larger than that of the control group 4.8±2.1 mm (t=3.683, P<0.001). The positive rate of a corneal scrape was 97.2% in the corticosteroid group and 90.6% in the control group, with no significant difference between the groups (χ2=1.633, P=0.201). Only 1 case (2.8%) in the corticosteroid group was cured by antifungal drugs, which was significantly lower than that of the control group, with 34 cases (19.4%) (χ2=5.983, P=0.014). Penetrating keratoplasty was performed in 22 cases (61.1%) in the corticosteroid group, a proportion that was significantly higher than that in the control group, with 55 cases (31.4%) (χ2=11.351, P=0.001). A corrected distance visual acuity of less than 0.3 after antifungal therapy was recorded in 32 cases (88.9%) in the corticosteroid group, a proportion which was significantly higher than in the control group, 110 cases (62.8%) (χ2=9.194, P=0.002). Conclusions: Corticosteroid use before a diagnosis of fungal keratitis can increase the range of lesions, while antifungal drugs seem to be less effective, which increases the probability of penetrating keratoplasty and a poorer outcome. Key words: corticosteroid; fungal keratitis; prognosis

Objective To evaluate the efficacy of debridement and biological amniotic membrane transplantation combined with subconjunctival injection of antifungal drugs for fungal keratitis.Methods Thirty nine eyes of 39 patients with fungal keratitis were enrolled in this study.The patients underwent corneal debridement combined with biological amniotic membrane transplantation.Subconjunctival injection of antifungal drugs and antifungal eye drops were used after operation.The follow up time was 3 to 6 months.The healing of corneal ulcer,amniotic membrane and visual acuity were investigated under slit lamp microscope.Results Corneal ulcer in 36 cases healed.3 patients underwent biological amniotic membrane transplantation again because of biological amniotic membrane falling off and corneal ulcer healed after transplantation and local antifungal drugs.Conclusion Debridement combined with biological amniotic membrane transplantation and antifungal drugs were effective for the treatment of fungal keratitis. Key words: Membrane, amniotic ; Transplantation ; Injection, subconjunctival ; Keratitis, fungal

To determine if pretreatment with antifungal agents is predictive of worse clinical outcome in a fungal keratitis clinical trial. Non-pre-specified subgroup analysis of a randomized controlled trial in a tertiary hospital. Three hundred twenty-three fungal ulcer cases with an enrolment visual acuity of 20/40 to 20/400. The Mycotic Ulcer Treatment Trial I was a randomized, double-masked trial to determine the optimal treatment for filamentous fungal keratitis at the Aravind Eye Care System, India. Enrolled cases were randomized to receive topical natamycin or voriconazole. Prior antifungal medication use, dose and duration were collected at enrolment. A subgroup analysis was performed to determine if patients using natamycin or azoles at presentation have worse clinical outcomes compared with those who were not pretreated. Three-month visual acuity (primary), 3-month infiltrate or scar size, corneal perforation and/or transplant and re-epithelialization time. Of the 323 patients enrolled, 44% presented on an antifungal agent. Pretreated patients had larger mean baseline infiltrate size (P < 0.001) and epithelial defect size (P = 0.02). Multivariate regression analysis demonstrated that pretreatment was associated with significantly worse 3-month visual acuity (P = 0.006), larger 3-month scar size (P < 0.001) and increased odds of corneal perforation and/or transplant (P = 0.001). Fungal keratitis that is smear-positive despite being pretreated with appropriate antifungal agents appears to be a risk factor for worse outcomes, likely a result of initial ulcer severity and treatment failure. These patients may benefit from more aggressive multimodal therapy at a tertiary centre.

The preparation and therapeutic effects of β-glucan-specific nanobodies and nanobody-natamycin conjugates in fungal keratitis.

Introduction: Fungal keratitis is a commonly encountered infection of the cornea which may lead to moderate to severe visual loss. Aim: To report the result of intra-stromal voriconazole in refractory keratomycosis. Method: Fungal keratitis is a commonly encountered infection of the cornea which may lead to moderate to severe visual loss. It may be caused by several species of fungi and accounts for nearly 50% of all cases of infectious keratitis in developing countries. The penetration of antifungal drugs into the deeper layers of cornea is sub-optimal, thus making it difficult to treat cases of deep fungal keratitis. We report two cases of refractory fungal keratitis; one caused by aspergillus fumigates and other by fusarium as seen on lactophenol cotton blue mount from scrapings. Both the cases were resistant to topical 5% natamycin and 1 % voriconazole and therefore, intra-stromal voriconazole reconstituted to 50 microns / 0.1 ml was injected circumferentially into the mid-stroma in close proximity to the ulcer margins in both the cases. Result: A marked reduction in the size of ulcer (both epithelial defect and infiltrates) was noted at 72 hours after intra-stromal voriconazole. A repeat injection was given in both the cases four days after the first injection. No complications were seen in any of the cases. Conclusion: Intra-stromal voriconazole offers an effective adjunctive in treating refractory keratomycosis as the direct deposition of drug into deeper stroma results into higher therapeutic concentrations into ulcer; thus obviating the need for therapeutic penetrating keratoplasty in such patients.