Evaluation of Visual Outcome of 2 Phakic Posterior Chamber Implantable Lenses in High Myopia: A Comparative Study.

PURPOSE: To evaluate and compare the visual outcomes of two phakic intraocular lenses in high myopia. METHODS: A prospective comparative study was undertaken on 50 eyes of 26 patients {age ≥21 years and divided into two groups (implantable collamer lens [ICL] V4c, n=25 eyes and refractive implantable lens [RIL], n=25 eyes)}. Patients were evaluated for uncorrected distance visual acuity (UCVA), best-corrected distance visual acuity, manifest refractive spherical equivalent (MRSE), contrast sensitivity, intraocular pressure, dilated fundus examination, trabecular-iris angle (TIA), anterior chamber depth, horizontal white-to-white diameter, wavefront aberrometry, and endothelial cell (EC) count. All patients were followed up until 6 months and additionally evaluated for anterior chamber inflammation, cataract, and lens vault. RESULTS: The baseline parameters (UCVA, MRSE, and EC count) and postoperative improvement in UCVA, contrast sensitivity, MRSE, EC loss, safety index, and efficacy index were comparable between both the lenses. The improvement in aberrometric profile was significantly better in the ICL group. The mean postoperative vault was higher in RIL group (434.88±162.48 µm vs. 547.24±159.83 µm, P=0.0173); however, the vault was within normal range in both the groups. The decrease in mean TIA was significantly higher in RIL group (8.58 vs. 13.45 µm, P=0.0073). CONCLUSION: Acrylic phakic lens can be considered as a suitable alternative to collamer lens for refractive correction of high myopia. The collamer lenses showed slight superiority in some qualitative visual parameters; however, collamer lenses do not present with subjective complaints in the patients.

Atypical acquired toxoplasmosis.

A 33-year-old male presented with unilateral painless vision loss with a history of sub-tenon steroid for the same. The fundus showed an elevated focus of retinochoroiditis with vitritis. On investigating for the cause, polymerase chain reaction test on the anterior chamber tap was found to be positive for Toxoplasma. Such confusing and atypical cases usually produce a clinical dilemma and should be managed in a stepwise manner. Ancillary investigations usually provide a clue to the clinician and should be performed without any hesitation.

First report on in-depth genome and comparative genome analysis of a metal-resistant bacterium Acinetobacter pittii S-30, isolated from environmental sample.

A newly isolated bacterium Acinetobacter pittii S-30 was recovered from waste-contaminated soil in Ranchi, India. The isolated bacterium belongs to the ESKAPE organisms which represent the major nosocomial pathogens that exhibit high antibiotic resistance. Furthermore, average nucleotide identity (ANI) analysis also showed its closest match (>95%) to other A. pittii genomes. The isolate showed metal-resistant behavior and was able to survive up to 5 mM of ZnSO4. Whole genome sequencing and annotations revealed the occurrence of various genes involved in stress protection, motility, and metabolism of aromatic compounds. Moreover, genome annotation identified the gene clusters involved in secondary metabolite production (biosynthetic gene clusters) such as arylpolyene, acinetobactin like NRP-metallophore, betalactone, and hserlactone-NRPS cluster. The metabolic potential of A. pittii S-30 based on cluster of orthologous, and Kyoto Encyclopedia of Genes and Genomes indicated a high number of genes related to stress protection, metal resistance, and multiple drug-efflux systems etc., which is relatively rare in A. pittii strains. Additionally, the presence of various carbohydrate-active enzymes such as glycoside hydrolases (GHs), glycosyltransferases (GTs), and other genes associated with lignocellulose breakdown suggests that strain S-30 has strong biomass degradation potential. Furthermore, an analysis of genetic diversity and recombination in A. pittii strains was performed to understand the population expansion hypothesis of A. pittii strains. To our knowledge, this is the first report demonstrating the detailed genomic characterization of a heavy metal-resistant bacterium belonging to A. pittii. Therefore, the A. pittii S-30 could be a good candidate for the promotion of plant growth and other biotechnological applications.

Ultra-wide field indocyanine green angiography in central serous chorioretinopathy.

PURPOSE: To study ultra-widefield indocyanine green angiography (ICGA) patterns in central serous chorioretinopathy (CSC). METHODS: A cross-sectional observational study was undertaken on 30 patients aged 20 to 60 years with CSC at the retina clinic of a tertiary care center. Of them, 43 eyes were affected by CSC, whereas 17 eyes were unaffected as the bilateral disease was observed in 13 patients. All patients were evaluated for best-corrected visual acuity, intraocular pressure, detailed slit-lamp bio-microscopy, indirect ophthalmoscopy, ultra-widefield imaging for pseudo color photograph, fundus autofluorescence (FAF), fundus fluorescein angiography (FFA), and ICGA, and macular swept-source optical coherence tomography (SSOCT) characteristics. RESULTS: The mean age of patients was 41.43 ± 8.81 years (range: 25-59 years). The median log MAR visual acuity in CSC eyes was 0.30 (range: 0.17-1.0), whereas it was 0 in non-CSC fellow eyes ( P < 0.001). Pachy-vessels and late hyperpermeability on ultra-widefield ICGA were observed in all eyes. Vortex vein anastomosis was present in 93% of the affected eyes versus 88.2% in unaffected fellow eyes ( P = 0.61). Disc and posterior poles were the sites of the maximum number of anastomoses in both affected and unaffected eyes ( P = 0.77). Asymmetry in vortex vein drainage of the macula was present in 88.4% of affected eyes and 88.2% of unaffected eyes. CONCLUSION: Studying the ICGA findings in CSC patients emphasized the role of choroidal circulation in pathogenesis as Pachy vessels were observed in all eyes affected with CSC and even fellow eyes of patients. Vortex vein anastomosis around the disc or posterior pole and asymmetric drainage from the macula were noted and could be contributing to CSC pathology.

Clinical Role of Smartphone Fundus Imaging in Diabetic Retinopathy and Other Neuro-retinal Diseases.

Purpose: In today's life, many electronic gadgets have the potential to become invaluable health care devices in future. The gadgets in this category include smartphones, smartwatches, and others. Till now, smartphone role has been highlighted on many occasions in different areas, and they continue to possess immense role in clinical documentation, clinical consultation, and digitalization of ocular care. In last one decade, many treatable conditions including diabetic retinopathy, glaucoma, and other pediatric retinal diseases are being imaged using smartphones.Methods: To comprehend this cumulative knowledge, a detailed medical literature search was conducted on PubMed/Medline, Scopus, and Web of Science till February 2021.Results: The included literature revealed a definitive progress in posterior segment imaging. From simple torch light with smartphone examination to present day compact handy devices with artificial intelligence integrated software's have changed the very perspectives of ocular imaging in ophthalmology. The consistently reproducible results, constantly improving imaging techniques, and most importantly their affordable costs have renegotiated their role as effective screening devices in ophthalmology. Moreover, the obtained field of view, ocular safety, and their key utility in non-ophthalmic specialties are also growing.Conclusions: To conclude, smartphone imaging can now be considered as a quick, cost-effective, and digitalized tool for posterior segment screenings, however, their definite role in routine ophthalmic clinics is yet to be established.

Dense Depth Estimation in Monocular Endoscopy With Self-Supervised Learning Methods.

We present a self-supervised approach to training convolutional neural networks for dense depth estimation from monocular endoscopy data without a priori modeling of anatomy or shading. Our method only requires monocular endoscopic videos and a multi-view stereo method, e.g., structure from motion, to supervise learning in a sparse manner. Consequently, our method requires neither manual labeling nor patient computed tomography (CT) scan in the training and application phases. In a cross-patient experiment using CT scans as groundtruth, the proposed method achieved submillimeter mean residual error. In a comparison study to recent self-supervised depth estimation methods designed for natural video on in vivo sinus endoscopy data, we demonstrate that the proposed approach outperforms the previous methods by a large margin. The source code for this work is publicly available online at https://github.com/lppllppl920/EndoscopyDepthEstimation-Pytorch.

Endoscopic navigation in the clinic: registration in the absence of preoperative imaging.

PURPOSE: Clinical examinations that involve endoscopic exploration of the nasal cavity and sinuses often do not have a reference preoperative image, like a computed tomography (CT) scan, to provide structural context to the clinician. The aim of this work is to provide structural context during clinical exploration without requiring additional CT acquisition. METHODS: We present a method for registration during clinical endoscopy in the absence of CT scans by making use of shape statistics from past CT scans. Using a deformable registration algorithm that uses these shape statistics along with dense point clouds from video, we simultaneously achieve two goals: (1) register the statistically mean shape of the target anatomy with the video point cloud, and (2) estimate patient shape by deforming the mean shape to fit the video point cloud. Finally, we use statistical tests to assign confidence to the computed registration. RESULTS: We are able to achieve submillimeter errors in registrations and patient shape reconstructions using simulated data. We establish and evaluate the confidence criteria for our registrations using simulated data. Finally, we evaluate our registration method on in vivo clinical data and assign confidence to these registrations using the criteria established in simulation. All registrations that are not rejected by our criteria produce submillimeter residual errors. CONCLUSION: Our deformable registration method can produce submillimeter registrations and reconstructions as well as statistical scores that can be used to assign confidence to the registrations.

The deformable most-likely-point paradigm.

In this paper, we present three deformable registration algorithms designed within a paradigm that uses 3D statistical shape models to accomplish two tasks simultaneously: 1) register point features from previously unseen data to a statistically derived shape (e.g., mean shape), and 2) deform the statistically derived shape to estimate the shape represented by the point features. This paradigm, called the deformable most-likely-point paradigm, is motivated by the idea that generative shape models built from available data can be used to estimate previously unseen data. We developed three deformable registration algorithms within this paradigm using statistical shape models built from reliably segmented objects with correspondences. Results from several experiments show that our algorithms produce accurate registrations and reconstructions in a variety of applications with errors up to CT resolution on medical datasets. Our code is available at https://github.com/AyushiSinha/cisstICP.

Evaluation and Stability Analysis of Video-Based Navigation System for Functional Endoscopic Sinus Surgery on In Vivo Clinical Data.

Functional endoscopic sinus surgery (FESS) is one of the most common outpatient surgical procedures performed in the head and neck region. It is used to treat chronic sinusitis, a disease characterized by inflammation in the nose and surrounding paranasal sinuses, affecting about 15% of the adult population. During FESS, the nasal cavity is visualized using an endoscope, and instruments are used to remove tissues that are often within a millimeter of critical anatomical structures, such as the optic nerve, carotid arteries, and nasolacrimal ducts. To maintain orientation and to minimize the risk of damage to these structures, surgeons use surgical navigation systems to visualize the 3-D position of their tools on patients' preoperative Computed Tomographies (CTs). This paper presents an image-based method for enhanced endoscopic navigation. The main contributions are: (1) a system that enables a surgeon to asynchronously register a sequence of endoscopic images to a CT scan with higher accuracy than other reported solutions using no additional hardware; (2) the ability to report the robustness of the registration; and (3) evaluation on in vivo human data. The system also enables the overlay of anatomical structures, visible, or occluded, on top of video images. The methods are validated on four different data sets using multiple evaluation metrics. First, for experiments on synthetic data, we observe a mean absolute position error of 0.21mm and a mean absolute orientation error of 2.8° compared with ground truth. Second, for phantom data, we observe a mean absolute position error of 0.97mm and a mean absolute orientation error of 3.6° compared with the same motion tracked by an electromagnetic tracker. Third, for cadaver data, we use fiducial landmarks and observe an average reprojection distance error of 0.82mm. Finally, for in vivo clinical data, we report an average ICP residual error of 0.88mm in areas that are not composed of erectile tissue and an average ICP residual error of 1.09mm in areas that are composed of erectile tissue.

Image-Based Navigation for Functional Endoscopic Sinus Surgery Using Structure From Motion.

Functional Endoscopic Sinus Surgery (FESS) is a challenging procedure for otolaryngologists and is the main surgical approach for treating chronic sinusitis, to remove nasal polyps and open up passageways. To reach the source of the problem and to ultimately remove it, the surgeons must often remove several layers of cartilage and tissues. Often, the cartilage occludes or is within a few millimeters of critical anatomical structures such as nerves, arteries and ducts. To make FESS safer, surgeons use navigation systems that register a patient to his/her CT scan and track the position of the tools inside the patient. Current navigation systems, however, suffer from tracking errors greater than 1 mm, which is large when compared to the scale of the sinus cavities, and errors of this magnitude prevent from accurately overlaying virtual structures on the endoscope images. In this paper, we present a method to facilitate this task by 1) registering endoscopic images to CT data and 2) overlaying areas of interests on endoscope images to improve the safety of the procedure. First, our system uses structure from motion (SfM) to generate a small cloud of 3D points from a short video sequence. Then, it uses iterative closest point (ICP) algorithm to register the points to a 3D mesh that represents a section of a patients sinuses. The scale of the point cloud is approximated by measuring the magnitude of the endoscope's motion during the sequence. We have recorded several video sequences from five patients and, given a reasonable initial registration estimate, our results demonstrate an average registration error of 1.21 mm when the endoscope is viewing erectile tissues and an average registration error of 0.91 mm when the endoscope is viewing non-erectile tissues. Our implementation SfM + ICP can execute in less than 7 seconds and can use as few as 15 frames (0.5 second of video). Future work will involve clinical validation of our results and strengthening the robustness to initial guesses and erectile tissues.

Anatomically Constrained Video-CT Registration via the V-IMLOP Algorithm.

Functional endoscopic sinus surgery (FESS) is a surgical procedure used to treat acute cases of sinusitis and other sinus diseases. FESS is fast becoming the preferred choice of treatment due to its minimally invasive nature. However, due to the limited field of view of the endoscope, surgeons rely on navigation systems to guide them within the nasal cavity. State of the art navigation systems report registration accuracy of over 1mm, which is large compared to the size of the nasal airways. We present an anatomically constrained video-CT registration algorithm that incorporates multiple video features. Our algorithm is robust in the presence of outliers. We also test our algorithm on simulated and in-vivo data, and test its accuracy against degrading initializations.

Automatic segmentation and statistical shape modeling of the paranasal sinuses to estimate natural variations.

We present an automatic segmentation and statistical shape modeling system for the paranasal sinuses which allows us to locate structures in and around the sinuses, as well as to observe the natural variations that occur in these structures. This system involves deformably registering a given patient image to a manually segmented template image, and using the resulting deformation field to transfer labels from template to patient. We use 3D snake splines to correct errors in the deformable registration. Once we have several accurately segmented images, we build statistical shape models for each structure in the sinus allowing us to observe the mean shape of the population, as well as the variations observed in the population. These shape models are useful in several ways. First, regular video-CT registration methods are insufficient to accurately register pre-operative computed tomography (CT) images with intra-operative endoscopy video because of deformations that occur in structures containing high amounts of erectile tissue. Our aim is to estimate these deformations using our shape models in order to improve video-CT registration, as well as to distinguish normal variations in anatomy from abnormal variations, and automatically detect and stage pathology. We can also compare the mean shape and variances of different populations, such as different genders or ethnicities, and observe the differences and similarities, as well as of different age groups, and observe the developmental changes that occur in the sinuses.