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3. Potential new fluoroquinolone treatments for suspected bacterial keratitis

Author

Timothy Neal, Stephen B Kaye, Stephen Tuft, Tobi Somerville, Gabriela Czanner, Keri McLean, Rose Herbert, Mary Caddick, and Shakeel Herwitker

Subjects
Ophthalmology, RE1-994
Abstract

Topical fluoroquinolones (FQs) are an established treatment for suspected microbial keratitis. An increased FQ resistance in some classes of bacterial pathogens is a concern. Some recently developed FQs have an extended spectrum of activity, making them a suitable alternative for topical ophthalmic use. For example, the new generation FQs, avarofloxacin, delafloxacin, finafloxacin, lascufloxacin, nadifloxacin, levonadifloxacin, nemonoxacin and zabofloxacin have good activity against the common ophthalmic pathogens such as Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pneumoniae and several of the Enterobacteriaceae. However, because there are no published ophthalmic break-point concentrations, the susceptibility of an isolated micro-organism to a topical FQ is extrapolated from systemic break-point data and wild type susceptibility. The purpose of this review is to compare the pharmacokinetics and pharmacodynamics of the FQs licensed for topical ophthalmic use with the same parameters for new generation FQs. We performed a literature review of the FQs approved for topical treatment and the new generation FQs licensed to treat systemic infections. We then compared the minimum inhibitory concentrations (MIC) of bacterial isolates and the published concentrations that FQs achieved in the cornea and aqueous. We also considered the potential suitability of new generation FQs for topical use based on their medicinal properties. Notably, we found significant variation in the reported corneal and aqueous FQ concentrations so that reliance on the reported mean concentration may not be appropriate, and the first quartile concentration may be more clinically relevant. The provision of the MIC for the microorganism together with the achieved lower (first) quartile concentration of a FQ in the cornea could inform management decisions such as whether to continue with the prescribed antimicrobial, increase the frequency of application, use a combination of antimicrobials or change treatment.

Published
2022
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4. Standard automated perimetry using size III and size V stimuli in advanced stage glaucoma: an observational cross-sectional comparative study

Author

Tobi Somerville, Gabriela Czanner, Fiona J Rowe, Devindra Sood, and Ishaana Sood

Subjects
Medicine
Abstract

Objectives In this study, we sought to evaluate the extent of further visual field that could be assessed when using stimulus size V in standard automated perimetry compared with size III in advanced stage glaucoma and whether cut-off values could be determined for when to switch from size III to size V.Design Prospective cross-sectional study.Setting Single-centre outpatient eye clinic in India (New Delhi).Participants Advanced stage glaucoma defined as stages 3–4.Intervention Central static perimetry with Octopus 900 G programme (size III stimulus dynamic strategy) and low vision central programme (size V stimulus dynamic strategy).Primary and secondary outcome measures Visual field assessment for right and left eyes with both sizes III and V were undertaken within one clinic visit.Results We recruited 126 patients (170 eyes). Mean patient age at assessment was 55.86 years (SD 15.15). Means (SD) for size III versus size V, respectively, were 6.94 dB (5.58) and 12.98 dB (7.77) for mean sensitivity, 20.02 dB (5.67) and 19.22 dB (7.74) for mean deviation, 5.89 dB (2.29) and 7.69 dB (2.78) for standard loss variance and 3.32 min (1.07) and 6.40 min (1.43) for test duration. All except mean deviation were significantly different between size III and V tests.Conclusion Useful visual field information was obtained with size V stimuli which allowed continued monitoring of these patients that was not possible with size III. Increased test duration, standard loss variance and mean sensitivity were found with size V, as expected, given that more visual responses were obtained with the increased target size. A switch from size III to V may be considered when mean sensitivity reaches 10 dB and/or mean deviation reaches 18 dB.

Published
2021
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5. Deep sclerectomy and trabeculectomy augmented with Mitomycin C: 2-year post-operative outcomes

Author

Tobi Somerville, Mark Batterbury, Rahul Dwivedi, Anshoo Choudhary, Clare Rogers, and Robert Cheeseman

Subjects
medicine.medical_specialty, Intraocular pressure, Visual acuity, genetic structures, medicine.medical_treatment, Mitomycin, Glaucoma, Trab, Trabeculectomy, 03 medical and health sciences, Cellular and Molecular Neuroscience, 0302 clinical medicine, Postoperative Complications, Deep sclerectomy, Ophthalmology, Mitomycin C, medicine, Glaucoma surgery, Humans, Intraocular Pressure, Retrospective Studies, business.industry, SARS-CoV-2, COVID-19, medicine.disease, Sensory Systems, eye diseases, Treatment Outcome, 030221 ophthalmology & optometry, sense organs, medicine.symptom, Complication, business, 030217 neurology & neurosurgery, Follow-Up Studies
Abstract

Purpose Two-year post-operative outcomes of both deep sclerectomy (DS) and trabeculectomy surgery (Trab) augmented with Mitomycin C (MMC) at a single tertiary eye centre. Methods Retrospective review of DS + MMC and trabeculectomy + MMC at a single centre between February 2015 and March 2018. Patients with a minimum of 12-month follow-up were included. Post-operative follow-up: day 1, week 1, months 1/3/6/12/18/24. Primary outcomes: changes in intraocular pressure (IOP) and changes in LogMAR visual acuity (BCVA) pre- and post-procedure. Secondary outcomes: changes in number of eye drops, number of follow-up clinic visits, post-operative complications and further surgical interventions. Complete success: IOP ≤ 21 mmHg off all IOP-lowering medications. Qualified success: IOP ≤ 21 mmHg on medication. Failure: IOP > 21 mmHg at 24 months or ≤ 5 mmHg on 2 consecutive follow-up visits after 3 months +/− additional incisional glaucoma surgery +/− loss of light perception. Statistical analysis performed using Microsoft Excel + SPSS. Results 90 eyes: DS + MMC = 46 eyes, Trab + MMC = 44 eyes. DS + MMC v Trab + MMC: mean pre-op IOP = 19.57 mmHg v 18.89 mmHg, significantly reduced at all post-operative time-points for both groups (p < 0.001). Mean IOP reduction from baseline = 33.94% v 38.39%; > 30% IOP reduction = 54.35% v 68.18%. IOP ≤ 16 mmHg = 82.61% (38/46) v 95.46% (42/44), IOP ≤ 12 mmHg = 52.17% (24/46) v 72.72% (32/44). Complete success = 67.39% v 61.36%, qualified success = 26.09% v 29.55%, failure = 6.52% v 9.09%. Post-op BCVA: no statistically significant differences between two groups (p = 0.09). Mean pre-op drops v post-op drops = 2.98 v 0.38 (DS + MMC; p < 0.001); 2.68 v 0.39 (Trab + MMC; p < 0.001). Further surgical intervention = 13% v 29.55%. Mean number of post-op clinic visits DS + MMC v Trab + MMC = 10.09 v 13.02 (p = 0.005). Conclusion Both procedures achieve sustained intraocular pressure and drop reduction at 2 years post-op. DS + MMC has lower complication rates requiring less intervention and significantly fewer clinic visits, which may be an important factor for deciding surgical management of glaucoma patients in the era of Covid-19 to reduce patient/clinician exposure to the virus.

Published
2021

6. Recurrent microbial keratitis and endogenous site Staphylococcus aureus colonisation

Author

Jayendra Shankar, Stephen B. Kaye, Sarah Aldwinckle, Malcolm J. Horsburgh, Tobi Somerville, Timothy Neal, and Henri Sueke

Subjects
Male, 0301 basic medicine, Staphylococcus aureus, medicine.medical_specialty, Conjunctiva, Corneal diseases, lcsh:Medicine, Nose, medicine.disease_cause, Gastroenterology, Article, Keratitis, Arthritis, Rheumatoid, Cornea, 03 medical and health sciences, 0302 clinical medicine, Internal medicine, Throat, medicine, Humans, lcsh:Science, Multidisciplinary, Diagnostic Tests, Routine, business.industry, lcsh:R, Middle Aged, Staphylococcal Infections, medicine.disease, 030104 developmental biology, medicine.anatomical_structure, Carriage, Rheumatoid arthritis, 030221 ophthalmology & optometry, Pharynx, Female, lcsh:Q, Infection, business
Abstract

This study investigated Staphylococcus aureus carriage in patients with microbial keratitis (MK). 215 patients with MK, 60 healthy controls and 35 patients with rheumatoid arthritis (RA) were included. Corneal scrapes were collected from patients with MK. Conjunctival, nasal and throat swabs were collected from the non-MK groups on a single occasion and from the MK group at presentation and then at 6 and 12 weeks. Samples were processed using conventional diagnostic culture. 68 (31.6%) episodes of clinically suspected MK were classed as recurrent. Patients with recurrent MK had a higher isolation rate of S. aureus from their cornea than those with a single episode (p S. aureus from their conjunctiva compared to control participants, 20.6% (14/68) versus 3% (5/60) respectively (p = 0.01). Significantly more patients with recurrent MK (12/68, 17.6%) were found to have S. aureus isolated from both their conjunctiva and nose than those with a single episode of MK (7/147, 4.8% p = 0.002) and compared to patients in the control group (3/60, 5.0% p = 0.03). The results indicate that patients with recurrent MK have higher rates of carriage of S. aureus suggesting endogenous site colonisation as a possible source of recurrent infection.

Published
2020

7. Use of a corneal impression membrane and PCR for the detection of herpes simplex virus type-1

Author

Matthias Brunner, Jayavani Myneni, Tara Rajhbeharrysingh, Stephen B. Kaye, Caroline E Corless, Timothy Neal, Stephanie Tiew, and Tobi Somerville

Subjects
Adult, Male, 0301 basic medicine, Microbiology (medical), medicine.medical_specialty, Serial dilution, 030106 microbiology, HSV keratitis, Herpesvirus 1, Human, Real-Time Polymerase Chain Reaction, medicine.disease_cause, Microbiology, Specimen Handling, Keratitis, Cornea, Clinical study, Random order, Young Adult, 03 medical and health sciences, medicine, Humans, Aged, DNA Primers, Aged, 80 and over, Cycle threshold, business.industry, Herpes Simplex, General Medicine, Middle Aged, medicine.disease, Dermatology, 030104 developmental biology, Real-time polymerase chain reaction, Herpes simplex virus, Molecular Diagnostic Techniques, DNA, Viral, Female, business
Abstract

Purpose. To investigate the use of a corneal impression membrane (CIM) for the detection of herpes simplex virus type 1 (HSV-1) in suspected herpes simplex keratitis (HSK). Methodology. In the laboratory study, swabs and CIMs made from polytetrafluoroethylene were spiked with different concentrations of HSV-1. DNA was extracted and real-time PCR undertaken using two sets of primers. In the clinical study, consecutive patients presenting with suspected HSK were included. For each patient, samples were collected from corneal lesions with a swab and a CIM in random order. Clinical details were collected using a standardized clinical form and patients were categorized into probable, presumed and possible HSK. Results. There was no difference in the performance of both primer sets for all HSV-1 dilutions (P=0.83) using a CIM or between a CIM and a swab (P=0.18). In total, 110 patients were included. Overall, 73 patients (66.4 %) had probable, 20 patients (18.2 %) presumed and 17 patients (15.5 %) possible HSV-1 keratitis. The HSV-1 detection rate was significantly higher using a CIM (40/110, 36.4 %) than a swab (28/110, 25.5 %) (P=0.004). In the probable HSV keratitis group, the detection rate using a CIM was 43.8 % compared to 27.4 % for a swab (P=0.004). The cycle threshold values obtained for the conjunctival swabs were higher than those obtained for the CIMs (P

Published
2019

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