In Vivo Quantification of Bacterial Keratitis with Optical Coherence Tomography
ABSTRACT To quantify the human corneal inflammatory response in treated bacterial keratitis with long-wavelength anterior segment optical coherence tomography (AS-OCT).
Patients with clinically suspected bacterial keratitis were recruited from the corneal service at Southampton Eye Unit, UK. Patients underwent AS-OCT and slit-lamp examination on presentation (day 0) and days 3, 7, and 14 of treatment. Corneal thickness (CT) in the infiltrated area, infiltrate thickness (IT), and infiltrate width (IW) were measured on high-resolution AS-OCT scans. Mean values for each day and rates of change for each interval were calculated and compared (one-way ANOVA, paired t-test).
Twenty-six eyes of 26 patients were recruited. Mean CT and IT on presentation were 905 μm and 388 μm, respectively. On days 3, 7, and 14, CT and IT decreased to 753 μm and 320 μm (P < 0.01), 678 μm and 296 μm (P < 0.01), and 584 μm and 207 μm (P < 0.01), respectively. Mean IW, 1498 μm on presentation, did not change during treatment (P > 0.30). Mean daily rate of CT reduction was faster in the early (days 0-3) compared to late (days 7-14) phase (4.49% vs. 1.33%, P = 0.006). Mean daily rate of IT reduction was no different in early, middle, and late phases (5.41% vs. 1.19% vs. 3.38%, P > 0.01). In the late phase, IT decreased faster than CT (3.38% vs. 1.33%, P = 0.003).
CT and IT decreased significantly by day 3 in resolving bacterial keratitis. The rapid early phase reduction in IT and CT was followed by rapid late phase IT reduction. This study demonstrates that serial AS-OCT examination can be used to monitor in vivo the clinical course of inflammatory disease.
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ABSTRACT: OBJECTIVE: To determine the intra and inter-user reliability of central corneal thickness (CCT) measurements obtained using a portable spectral-domain optical coherence tomography (SD-OCT) device in healthy feline eyes. ANIMALS: Twenty clinically normal cats. PROCEDURES: Gentle manual restraint was utilized for proper animal positioning. Central corneal thickness measurements were obtained from both eyes of each animal three times by two operators in succession. A 6 mm, corneal pachymetry protocol was performed using the Optovue(®) iVue SD-OCT system. The CCT was automatically calculated using the pachymetry software generated from eight radial scans, 6 mm in length. The CCT was recorded for each operator and compared statistically for both intra and inter-user reliability. RESULTS: Twenty cats (11 CM, 9 SF) with a mean age of 4.7 years were examined. The mean CCT for all eyes examined was 629.08 ± 47.05 μm. No significant difference in CCT was found based on the eye examined (OD vs. OS) or age of the animal. However, the CCT of spayed females was significantly higher (42.64 ± 18.0 μm) as compared to castrated males (P = 0.03). There was no significant difference in CCT measurements between replicates performed by the same operator or between operators. The mean difference in CCT between operators was 0.38 μm. The coefficient of variation for each user and between users was very low (range 0.68-1.5%). The intra-class correlation coefficient comparing operators was 0.975. CONCLUSIONS: The Optovue(®) iVue SD-OCT device is capable of obtaining CCT measurements with excellent intra and interoperator reliability in healthy feline eyes.Veterinary Ophthalmology 01/2013; DOI:10.1111/vop.12029 · 1.09 Impact Factor
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ABSTRACT: The objective of this study was to determine central corneal thickness (CCT) and the intra- and interuser reliability using a portable spectral-domain optical coherence tomography (SD-OCT) device in canine eyes. Twenty clinically normal dogs were examined. CCT measurements were obtained from both eyes of each animal three times by two operators in succession. The CCT was automatically calculated using the pachymetry software generated from eight radial scans, 6 mm in length. Mean canine CCT was 606.83±39.45 μm for all eyes examined. There was no significant difference in CCT based on the eye examined (OD vs OS), age or gender of the animal. There was no significant difference in CCT between replicates performed by the same operator; however, a small but significant difference was noted in CCT between operators. The mean difference in CCT between operators was 1.9 μm (P=0.03). The coefficient of variation for each user and between users was very low (range 0.64-1.7 per cent). The intraclass correlation coefficient comparing operators was 0.975. Based on these results, the SD-OCT device evaluated is capable of obtaining precise CCT measurements with excellent intra- and interoperator reliability in canine eyes.05/2013; DOI:10.1136/vr.101530
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ABSTRACT: The aim of this study was to develop and characterize a new contact lens-associated fungal keratitis rat model and to assess the ability of non-invasive spectral-domain optical coherence tomography (SD-OCT) to detect pathological changes in vivo in fungal keratitis. We used SD-OCT to image and measure the cornea of Sprague Dawley rats. Fusarium infection was initiated in the rat eye by fitting Fusarium solani-soaked contact lenses on the experimental eye, while the control animals received contact lenses soaked in sterile saline. The fungal infection was monitored with periodic slit-lamp examination and in vivo SD-OCT imaging of the rat eye, and confirmed by histology, counting of viable fungi in the infected rat cornea, and PCR with specific primers for Fusarium sp. We imaged and measured the rat cornea with SD-OCT. Custom-made contact lenses were developed based on the OCT measurements. Incubation of contact lenses in a F. solani suspension resulted in biofilm formation. We induced contact lens-associated Fusarium keratitis by fitting the rat eyes for 4 h with the Fusarium-contaminated contact lenses. The SD-OCT images of the cornea correlated well with the slit-lamp and histopathological results and clearly defined clinical signs of infection, namely, increased corneal thickening, loss of epithelial continuity, hyper-reflective areas representing infiltrates, and endothelial plaques characteristic of fungal infection. Moreover, in three cases, SD-OCT detected the infection without any clear findings on slit-lamp examination. Infection was confirmed with histological fungal staining, PCR, and microbiological culture positivity. We developed a highly reproducible rat contact lens model and successfully induced contact lens-associated Fusarium keratitis in this model. The clinical presentation of contact lens-associated Fusarium keratitis in the rat model is similar to the human condition. SD-OCT is a valuable tool that non-invasively revealed characteristic signs of the fungal infection and could provide sensitive, objective monitoring in fungal keratitis.Molecular vision 12/2013; 19:2596-605. · 2.25 Impact FactorThis article is viewable in ResearchGate's enriched formatRG Format enables you to read in context with side-by-side figures, citations, and feedback from experts in your field.