High-resolution genotyping of Pseudomonas aeruginosa strains linked to acute post cataract surgery endophthalmitis outbreaks in India

BACKGROUND: Investigation of two independent outbreaks of post cataract surgery endophthalmitis identified the reservoir of epidemic strains of P. aeruginosa. METHODS: Patient isolates cultured from vitreous fluid of all the nine cases and from the peripheral devices of phacoemulsification machine were subjected to high-resolution Fluorescent Amplified Fragment Length Polymorphism (FAFLP) analysis. RESULTS: FAFLP based genotyping of the isolates confirmed nosocomial transmission. Although biochemical characterization and antibiotic susceptibility profiles grouped all the isolates together, FAFLP based genotyping revealed that, all the outbreak isolates were derived from 2 different strains, with independent origins. One group of isolates was traced to phacoprobe and the second one to the internal tubing system of the phacoemulsification machine used in cataract surgery. In silico analysis indicated possible evolution in both the clusters of P. aeruginosa isolates due to genetic polymorphisms. The polymorphisms were mapped to gene products (cell envelope, outer membrane proteins) possibly having significant role in pathogenesis. CONCLUSION: The present study is probably the first one to apply FAFLP typing successfully to investigate outbreaks of postoperative endophthalmitis (POE) in an ophthalmic setting, which was able to identify the source, and helped to make rational decisions on sterilization procedures that halted more cases of infection in these hospitals

Qualitative ultrasound biomicroscopy in glaucoma

Background: UBM is a high-resolution ultrasound technique which allows non-invasive, in vivo imaging of the anterior segment and iridocorneal angle. Purpose: This video is compilation of short video clips and images which gives description on identification of angle closure due to pupillary block, peripheral anterior synechiae, iris bombe, plateau iris, supra ciliary effusion, and malignant glaucoma. It also shows video demonstrating partially and fully patent iridotomy and features of trabeculectomy bleb. Synopsis: This video summarizes importance of UBM application in angle closure glaucoma to understand its pathophysiology by showing the relationship between the peripheral iris, trabecular meshwork and ciliary processes. Highlights: UBM provides two-dimensional, grayscale images of the angle structures and allows identification of non-pupillary block mechanism in angle closure glaucoma, which can be recorded for qualitative and quantitative analyses. Video Link: https://youtu.be/prsmGnR8jY

Imaging iridotrabecular contact in angle closure

Background: With ultrasound biomicroscopy (UBM), radial scans are taken by using a typical ciliary process, to show the details of the iridocorneal angle, the anterior surface of the ciliary body, and its relation to the posterior iris. Appositional closure represents potentially reversible contact between the peripheral iris and trabecular meshwork. The appositional closure can further be classified according to the configuration of iridotrabecular contact (ITC). UBM can be performed in dark and light conditions, which has been shown to be useful for detecting changes in iridocorneal angle configuration associated with dark and light. Purpose: To image ITC configuration in appositional angle closure and also image iridocorneal angle in dark and bright light room illumination. Synopsis: UBM demonstrates two types of ITC configuration in appositional closure which are, B-type and S-type. It can also demonstrate the presence of sinus of Mapstone in S-type of ITC. Highlights: UBM allows imaging of dynamic changes in the iris and shows that the degree of appositional angle closure is a dynamic process that can change rapidly depending on the lighting conditions. Video link: https://youtu.be/tgN4SLyx6wQ

Qualitative ultrasound biomicroscopy of the normal anterior segment

Background: Ultrasound biomicroscopy (UBM) is a high-resolution ultrasound technique that allows noninvasive, in vivo imaging of the ocular anterior segment structures. Before interpreting the UBM images of the diseased eyes, it is essential to understand the structures seen in the UBM image of the normal eye. Purpose: This video is a compilation of short video clips that gives description of identification of the anterior segment structures in the axial scan, a cross-sectional view through the anterior chamber angle region of a normal subject in a radial scan, and identification of ciliary processes in the transverse scan. Synopsis: UBM provides two-dimensional, grayscale images of the various anterior segment structures and allows all these structures to be imaged simultaneously, in their normal state, as they occur in the living eye. The real-time image is displayed on a video monitor and can be recorded for qualitative and quantitative analysis. Highlights: The video gives an overview of identification of normal anterior segment structures on UBM. Video link: https://youtu.be/3KooOp2Cn30

Sources of errors in measurement of retinal nerve fiber layer thickness using optical coherence tomography

Background: Optical coherence tomography (OCT)–obtained retinal nerve fiber layer (RNFL) thickness measurements allow for qualitative and quantitative assessment of RNFL thinning in glaucoma. Errors in data acquisition or in software analysis may result in artifacts and erroneous RNFL thickness measurements that may lead to an inaccurate clinical interpretation. Purpose: This video describes tips to recognize artifacts in RNFL thickness measurement in various OCT printouts. Synopsis: The video presents a series of OCT of optic nerve head printouts with artifacts and useful teaching points to identify the same and its source of error. Highlights: The technician must confirm the quality and accuracy of the acquired data before the patient returns to the physician with the final printout. Recognition of artifacts and identifying its source of error is critical to interpret the data accurately, avoiding erroneous clinical interpretation. Video Link: https://youtu.be/rRZVeTaivI

Quantitative ultrasound biomicroscopy of iridocorneal angle

Background: Ultrasound biomicroscopy (UBM) is a high-resolution ultrasound technique, which allows noninvasive, in vivo imaging of the ocular anterior segment structures. Purpose: This video gives a description of the identification of the iridocorneal angle structures in the cross-sectional view in a radial scan through a typical ciliary process and a guide toward measuring the angle parameters. Synopsis: UBM provides two-dimensional, grayscale images of the iridocorneal angle. The real-time image is displayed on a video monitor and can be recorded for qualitative and quantitative analysis. The angle parameters can be measured by in-built calipers in the machine software and manipulated by the examiner. Highlights: This video demonstrates UBM caliper positions as displayed on the monitor and marked by the examiner for the measurement of various anterior segment parameters of the eye. Video link: https://youtu.be/WTXMupYoyww

Radial peripapillary capillary network in optic disc anomalies with abnormal tissues on disc surface

Background: Optic disc anomalies with abnormal tissue on the disc surface includes, myelinated nerve fiber, optic disc drusen, and Bergmeister papillae. Imaging the radial peripapillary capillary (RPC) network in optic disc anomalies with optical coherence tomography–angiography (OCTA) can give information on the RPC network in these conditions. Purpose: This video describes the OCTA of optic nerve head and RPC network using the angio disc mode in cases of optic disc anomalies with abnormal tissue on the disc surface. Synopsis: This video presents characteristic features of RPC network in one eye each of myelinated nerve fiber, optic disc drusen, and Bergmeister papillae. Highlights: OCTA in optic disc anomalies with abnormal tissue on the disc surface show a dense RPC microvascular network. OCTA is an effective imaging modality to study vascular plexus/RPC and their alteration in these disc anomalies. Video link: https://youtu.be/zlflgijy56c