Machine learning-based automatic detection of novel coronavirus (COVID-19) disease.

The pandemic was announced by the world health organization coronavirus (COVID-19) universal health dilemma. Any scientific appliance which contributes expeditious detection of coronavirus with a huge recognition rate may be excessively fruitful to doctors. In this environment, innovative automation like deep learning, machine learning, image processing and medical image like chest radiography (CXR), computed tomography (CT) has been refined promising solution contrary to COVID-19. Currently, a reverse transcription-polymerase chain reaction (RT-PCR) test has been used to detect the coronavirus. Due to the moratorium period is high on results tested and huge false negative estimates, substitute solutions are desired. Thus, an automated machine learning-based algorithm is proposed for the detection of COVID-19 and the grading of nine different datasets. This research impacts the grant of image processing and machine learning to expeditious and definite coronavirus detection using CXR and CT medical imaging. This results in early detection, diagnosis, and cure for the accomplishment of COVID-19 as early as possible. Firstly, images are preprocessed by normalization to enhance the quality of the image and removing of noise. Secondly, segmentation of images is done by fuzzy c-means clustering. Then various features namely, statistical, textural, histogram of gradients, and discrete wavelet transform are extracted (92) and selected from the feature vector by principle component analysis. Lastly, k-NN, SRC, ANN, and SVM are used to make decisions for normal, pneumonia, COVID-19 positive patients. The performance of the system has been validated by the k (5) fold cross-validation technique. The proposed algorithm achieves 91.70% (k-Nearest Neighbor), 94.40% (Sparse Representation Classifier), 96.16% (Artificial Neural Network), and 99.14% (Support Vector Machine) for COVID detection. The proposed results show feature combination and selection improves the performance in 14.34 s with machine learning and image processing techniques. Among k-NN, SRC, ANN, and SVM classifiers, SVM shows more efficient results that are promising and comparable with the literature. The proposed approach results in an improved recognition rate as compared to the literature review. Therefore, the algorithm proposed shows immense potential to benefit the radiologist for their findings. Also, fruitful in prior virus diagnosis and discriminate pneumonia between COVID-19 and other pandemics.

Novel coronavirus (COVID-19) diagnosis using computer vision and artificial intelligence techniques: a review.

The universal transmission of pandemic COVID-19 (Coronavirus) causes an immediate need to commit in the fight across the whole human population. The emergencies for human health care are limited for this abrupt outbreak and abandoned environment. In this situation, inventive automation like computer vision (machine learning, deep learning, artificial intelligence), medical imaging (computed tomography, X-Ray) has developed an encouraging solution against COVID-19. In recent months, different techniques using image processing are done by various researchers. In this paper, a major review on image acquisition, segmentation, diagnosis, avoidance, and management are presented. An analytical comparison of the various proposed algorithm by researchers for coronavirus has been carried out. Also, challenges and motivation for research in the future to deal with coronavirus are indicated. The clinical impact and use of computer vision and deep learning were discussed and we hope that dermatologists may have better understanding of these areas from the study.

Spontaneous Resolution of a Rapidly Formed Dense Cataract Following Nd: YAG Laser Peripheral Iridotomy in a Case of Pigmentary Glaucoma.

A 54-year-old man was referred for a senior opinion. His vision had acutely dropped in his right eye from 6/6 to hand movements following Nd:YAG laser peripheral iridotomy for treatment of pigmentary glaucoma. A dense rosette posterior subcapsular cataract had formed in his right eye rapidly after surgery. Within 4 weeks the cataract resolved spontaneously and his vision returned to 6/6. It is hypothesized that a dual mechanism caused the rapidly formed cataract. Shockwaves stemming from Nd:YAG laser resulted in a reversible misalignment of the lenticular fibers, and localized direct damage to capsule caused osmotic imbalance and fluid collection between lamellae. Restoration of the osmotic balance, repair, and formation of lens fibers and clearing of vacuoles led to the resolution of the cataract. The proximity of the concave iris to the lens equator in pigmentary glaucoma was a predisposing factor. This highlights the importance of exercising great caution in using laser peripheral iridotomy in cases of pigmentary glaucoma, particularly if a higher laser power is used and considering initial conservative management of this complication.

Acute Secondary Optic Neuropathy as a Complication of a Single Episode of Acutely Raised Intraocular Pressure: A Case Series.

PURPOSE: The purpose of this case series is to report development of acute secondary optic neuropathy due to optic nerve injury associated with single episode of acutely raised intraocular pressure (IOP) of varying etiologies. PATIENTS AND METHODS: Retrospective review of a series of 3 consecutive cases diagnosed at University hospitals of Coventry and Warwickshire and review of published literature. RESULTS: Three cases, respectively, with Posner Schlossman syndrome, acute idiopathic hypertensive anterior uveitis, and primary acute angle-closure initially presented with raised IOPs of 38 to 68 mm Hg. All cases were treated initially with medical management and the primary acute angle-closure case had subsequent Nd:YAG laser peripheral iridotomy. All 3 cases developed acute optic nerve injury with reduced vision, an afferent pupillary defect and optic disc swelling which subsequently persisted as optic neuropathy with sectoral optic atrophy and disc pallor. CONCLUSIONS: This rare cases series highlights the importance of increased awareness of the possibility of developing acute secondary optic neuropathy in patients with acutely raised IOP. On the basis of the acute clinical features, including disc edema with disc hemorrhages and an afferent pupillary defect the most likely pathophysiology of the resultant optic nerve injury is the acute impact of high IOP on optic nerve head perfusion. This appears similar to nonarteritic anterior oschemic optic neuropathy. Other systemic and local risk factors may also contribute. Appropriate timely management to reduce the acutely raised IOP are essential but may not be sufficient in preventing optic neuropathy due to changes at presentation.

Secondary Glaucoma due to Iridescent Crystalline Particles Masquerading as Refractory Hypertensive Uveitis in an Eye With Irradiated Iris Melanoma.

PURPOSE: We report a previously unrecognized mechanism of secondary glaucoma due to iridescent crystalline particles released from an irradiated iris melanoma. It masqueraded as refractory hypertensive uveitis following uncomplicated phacoemulsification. MATERIALS AND METHODS: A 58-year-old gentleman had an iris melanoma that underwent successful regression following irradiation with proton beam radiotherapy. Three years later an uncomplicated phacoemulsification with intraocular lens implant was performed and subsequently the patient presented with apparently "refractory hypertensive uveitis." Closer examination identified unique iridescent crystalline particles originating from a disintegrating tumor and dispersing within the anterior chamber and drainage angle. The patient developed a unilateral secondary open-angle glaucoma attributable to these particles. Ultrasound biomicroscopy of the anterior segment confirmed absence of tumor recurrence or intrascleral spread and systemic investigations ruled out distant metastases. RESULTS: The intraocular pressure was refractory to maximal medical treatment, but was eventually controlled with trans-scleral diode laser cyclo-photocoagulation. CONCLUSIONS: This is the first report of a secondary glaucoma attributable to trabecular blockage with iridescent crystalline particulate material released from a disintegrating, previously irradiated, iris melanoma. Proton beam radiotherapy and possibly phacoemulsification may have played a role in triggering the release of these previously undescribed particles from the atrophied tumor surface. This unique mechanism of secondary glaucoma needs to be kept in mind in such rare cases. Trans-scleral cyclodiode laser may be used as a good initial option in such cases to minimize potential risk of tumor seeding with incisional glaucoma surgery.

Combined Acute Haemolytic and Secondary Angle Closure Glaucoma following Spontaneous Intraocular Haemorrhages in a Patient on Warfarin.

BACKGROUND: To report the first described case of combined haemolytic and acute angle closure glaucoma secondary to spontaneous intraocular haemorrhages in a patient on excessive anticoagulation. To the best of our knowledge, this is the first case reported in the literature presenting with raised intraocular pressure due to both mechanisms. CASE DESCRIPTION: A 90-year-old woman presented with acute pain and reduction in vision in the left eye. Her intraocular pressure (IOP) was 55 mm Hg. There were red tinted blood cells in the anterior chamber giving it a reddish hue. The patient was known to have advanced wet macular degeneration. She was taking oral warfarin for atrial fibrillation. Her international normalised ratio (INR) was 7.7. B-scan ultrasound of posterior segment showed vitreous and suprachoroidal haemorrhages. An ultrabiomicroscopic examination confirmed open angles. A diagnosis of haemolytic glaucoma secondary to intraocular haemorrhages was made. The IOP was controlled medically. Warfarin was withdrawn and oral vitamin K therapy was initiated leading to a rapid INR reduction. Three days later, her anterior chamber became progressively shallower causing a secondary acute angle closure which was managed medically. After 2 months, the left IOP was well-controlled without any medications and the eye was not inflamed. Her vision in that eye remained perception of light. CONCLUSION: Patients with suprachoroidal haemorrhages should be closely monitored as they might subsequently develop acute angle closure despite an initially open angle and well-controlled INR and IOP. Excessive anticoagulation needs to be prevented to minimise the risk of sight-threatening complications.

Rare case of post-cataract-surgery Prevotella endophthalmitis diagnosed by polymerase chain reaction DNA sequencing.

We report the presentation, diagnosis, and management of endophthalmitis caused by the opportunistic Prevotella species. The case was referred to us following uneventful phacoemulsification and intraocular lens implantation. Accurate identification of this rare cause of endophthalmitis was made using bacterial polymerase chain reaction DNA sequencing. Subsequent prompt modification of antibacterial therapy allowed resolution of signs and symptoms and significant visual recovery. To our knowledge, this is the first reported case of diagnosis and management of post-cataract-surgery endophthalmitis caused by the opportunistic Prevotella species.

Extension of retracted glaucoma drainage tube using a 22-gauge intravenous catheter in complex pediatric glaucoma.

PURPOSE: To describe the use of the readily available, sterile, and economical 22-gauge intravenous catheter (Venflon) as a preferable option for extending the tube of glaucoma drainage devices in cases of tube retraction in complex pediatric cases. METHODS: A report of noncomparative retrospective evaluation of 2 pediatric cases with tube retraction treated with the extension of the tube. The tube of the drainage devices (1 Baerveldt and 1 Molteno) was extended using a segment of a 22-gauge intravenous catheter (Venflon). The available follow-up for both the cases is 8.5 months. RESULTS: In both cases an adequate length of the tube was obtained in the anterior chamber. In the first case an excellent drainage bleb formed over the plate and the intraocular pressure (IOP) reduced from 28 to 11 mm Hg. In the second case only a 25% reduction of IOP (from 40 to 30 mm Hg) and a shallow bleb was seen for a few weeks only as extensive fibrosis over the plate limited the drainage. There has been no displacement of the tube in the follow-up period. CONCLUSIONS: The readily available, sterile, and economical 22-gauge intravenous catheter (venflon) segment is a structurally and functionally appropriate, and cost effective option for extension of both Baerveldt and Molteno drainage implants in complex pediatric cases. However other factors limiting drainage from tube, such as extensive scarring over the plate may limit the reduction of IOP.

Ocular decompression retinopathy after trabeculectomy with mitomycin-C for angle recession glaucoma.

A 45-year-old male presented with intractable glaucoma following 360-degree angle recession after blunt trauma. He underwent an uncomplicated trabeculectomy with mitomycin-C (MMC). Adequate precautions were taken to reduce the chances of sudden lowering of intraocular pressure (IOP). He did not have any intraoperative shallowing of the anterior chamber or postoperative hypotony, but still developed ocular decompression retinopathy. On detailed review of the previously reported cases we discovered that besides a large IOP drop after surgery, either the preoperative rise of IOP in all these cases was over a relatively short period or the course of their glaucomatous process was likely to have exposed them to intermittent spikes of high IOP. To our knowledge this factor has not been previously postulated in the pathophysiology of ocular decompression retinopathy. We illustrate this with a rare case of ocular decompression retinopathy after trabeculectomy with MMC for post-traumatic angle recession glaucoma.

Potential contamination of the G-probe used for transscleral cyclodiode.

AIM: To present a case where we noted occult contamination of the G-probe used for transscleral cyclodiode and to critically analyze the techniques used for making a G-probe suitable for repeated use. MATERIALS AND METHODS: Close microscopic examination of the G-probes used once for transscleral cyclodiode was done and a critical review of the literature on practice of reuse of the G-probe and the techniques used to "cleanse" the probe before reuse was performed. RESULTS: We noticed microscopic contamination of the G-probe by the tear film fluid in all the probes examined by us. The review of literature indicates that repeated use of the G-probe is not uncommon. The types of techniques used for making it suitable for repeated use indicate that it is not universally recognized that the lumen of the G-probe can accumulate fluid during the procedure, which makes it potentially hazardous when used for other patients. CONCLUSIONS: In our opinion the G-probe should not be reused as inadequately reprocessed G-probe can lead to risk of nosocomial infections, serious iatrogenic complications, and medico-legal problems.

Optimization of biometry for intraocular lens implantation using the Zeiss IOLMaster.

PURPOSE: To compare the accuracy of biometry using conventional A-scan ultrasonography and partial coherence interferometry, and to improve the accuracy of biometry by sequential audit of postoperative refractive error. METHODS: The study was performed in three phases. In phase 1, 20 consecutive patients undergoing routine phacoemulsification underwent biometry using both A-scan ultrasonography and the Zeiss IOLMaster (ZIOLM). A single experienced optometrist refracted all patients 2 weeks after surgery. The errors between expected and achieved refraction were calculated and compared between the two methods. In phases 2 and 3, a further 22 and 20 patients, respectively, were recruited and only the ZIOLM was used for biometry. The manufacturer's suggested A-constant was refined and the error between expected and achieved refraction was calculated. RESULTS: In phase 1, the median unexpected error for the ZIOLM was +0.63 (interquartile range +0.368 to +1.015) and for A-scan biometry was - 0.24 (interquartile range - 1.335 to +0.802). In phase 1 65% of patients' postoperative refractions were found to be within 1.0 D of emmetropia using the ZIOLM (55% using A-scan biometry). Refinements to the A-constant improved this to 95% by phase 3. CONCLUSION: An error was identified in IOL power estimation with the ZIOLM, when using the manufacturer's recommended A-constant (recommended and previously optimized ultrasound A-constant 118.0; ZIOLM optimized A-constant 118.6). Serial modifications to the A-constant were successful in reducing the unexpected error to well within the tolerance limits of published international standards.

Optimization of biometry for intraocular lens implantation using the Zeiss IOLMaster.

PURPOSE: To compare the accuracy of biometry using conventional A-scan ultrasonography and partial coherence interferometry, and to improve the accuracy of biometry by sequential audit of postoperative refractive error. METHODS: The study was performed in three phases. In phase 1, 20 consecutive patients undergoing routine phacoemulsification underwent biometry using both A-scan ultrasonography and the Zeiss IOLMaster (ZIOLM). A single experienced optometrist refracted all patients 2 weeks after surgery. The errors between expected and achieved refraction were calculated and compared between the two methods. In phases 2 and 3, a further 22 and 20 patients, respectively, were recruited and only the ZIOLM was used for biometry. The manufacturer's suggested A-constant was refined and the error between expected and achieved refraction was calculated. RESULTS: In phase 1, the median unexpected error for the ZIOLM was+0.63 (interquartile range+0.368 to+1.015) and for A-scan biometry was --0.24 (interquartile range--1.335 to+0.802). In phase 1 65% of patients' postoperative refractions were found to be within 1.0 D of emmetropia using the ZIOLM (55% using A-scan biometry). Refinements to the A-constant improved this to 95% by phase 3. CONCLUSION: An error was identified in IOL power estimation with the ZIOLM, when using the manufacturer's recommended A-constant (recommended and previously optimized ultrasound A-constant 118.0; ZIOLM optimized A-constant 118.6). Serial modifications to the A-constant were successful in reducing the unexpected error to well within the tolerance limits of published international standards.