1,721,003 research outputs found
Qualitative and quantitative analysis of filtering blebs with optical coherence tomography
No full textObjective: To provide a qualitative and quantitative analysis of filtering blebs with optical coherence tomography (OCT) in patients after primary trabeculectomy. Design: Evaluation of diagnostic technology. Participants: We retrospectively studied 20 eyes of 20 patients who had a fornix-based flap in primary trabeculectomy: 14 with mitomycin C (MMC) and 6 without MMC. Methods: Filtering blebs were examined using 2 types of OCTs working at a wavelength of 840 and 1310 nm. In this study, we analyzed both the OCT morphologic pattern and the internal structures of blebs, including bleb wall thickness, scleral flap thickness, and the route under the scleral flap, and quantified the reflectivity of the intrableb area. Results: Blebs were classified according to the Hirooka scheme in 3 OCT morphologic patterns: cystoid, diffuse, and layer type. The MMC was associated with the surgical success (100%). A significant association was found between good functionality and cystoid type with both devices: 840-nm OCT (p = 0.02) and 1310-nm OCT (p = 0.04). A significant difference in morphologic patterns was found using the 2 OCTs. There were no significant differences between successful and unsuccessful filtering surgery for intrableb structures. The reflectivity of filtering blebs correlated very well to the postoperative intraocular pressure (IOP; R2 = 0.90; p = 0.001) and to the reduction of IOP (R2 = 0.58; p = 0.001). Our method to quantify the reflectivity showed a significant degree of intergrader consensus (intraclass correlation coefficient = 0.99; < o 0.001). Conclusions: Although 840-nm OCT was not developed to assess the anterior segment, it may be considered a useful tool to evaluate the functionality of blebs in the postoperative period.Objet
Présentation d'une analyse qualitative et quantitative des bulles de filtration avec la tomographie par cohérence optique (TCO) des patients après une trabéculotomie primaire.
Nature
Évaluation de la technologie du diagnostic.
Participants
Nous avons étudié rétrospectivement 20 yeux de 20 patients qui avaient eu une trabéculotomie primaire avec lambeau à base fornix: 14 avec mitomycine C (MMC) et 6 sans MMC.
Méthodes
Examen des bulles de filtration avec deux types de TCO travaillant dans une longueur d'onde de 840 nm et 1310 nm. Dans cette étude, nous avons analysé par TCO la configuration morphologique et les structures internes des bulles, y compris l'épaisseur de leurs parois, l'épaisseur du volet scléral et le cheminement sous le rabat scléral, ainsi que quantifié la réflectivité de l'aire bullaire.
Résultats
Les bulles ont été classifiées selon le schéma Hirooka sous trois modèles morphologiques TCO : types cystoïdes, diffus et en couches. La MMC était associée à la réussite chirurgicale (100 %). L'on a constaté une association significative entre la fonctionnalité et le type cystoïde avec les deux dispositifs : TCO 840-nm (p=0,02) et TCO 1310-nm (p=0,04). L'on a constaté une différence significative entre les modèles morphologiques avec les deux TCO. Il n'y avait pas de différence significative entre les structures bullaires des chirurgies réussies vs. les échecs. La réflectivité de structures bullaires avait une très bonne corrélation avec la PIO postopératoire (R2=0,9;<0,001) et la réduction de la PIO (R2=0,58; p=0,001). Nos méthodes de quantification de la réflectivité ont démontré un important degré de consensus entre les classificateurs (CEC=0,99; p=0,001).
Conclusions
Bien qu'il ne soit pas développé pour évaluer le segment antérieur, le TCO 840-nm peut être considéré comme outil valide pour évaluer la fonctionnalité des bulles dans la période postopératoire
Flow density analysis in patients affected by Retinitis Pigmentosa with en face enhanced depth imaging angiography optical coherence tomography
No full textGlobal Spread of Coronavirus Disease 2019 and Malaria: An Epidemiological Paradox in the Early Stage of A Pandemic
Full text linkIn the current work, we discovered and analyzed the epidemiological paradox between coronavirus disease 2019 (COVID-19) and malaria in the initial phase of the ongoing pandemic. From the analysis of distribution data, the endemic presence of malaria seems to protect some populations from COVID-19 outbreak, particularly in the least developed countries. In this sense, molecular and genetic variations associated with malaria (e.g., in ACE2) might play a protective role against coronavirus infection. Moreover, the mechanism of action of some antimalarial drugs, e.g., the antiviral function, suggests their potential role in the chemoprophylaxis of coronavirus epidemics, despite possible adverse effects (e.g., retinal toxicity). All these data provide important insights to understand the spreading mechanisms of COVID-19, and to direct scientific research toward the study of some currently available medications
The Waiver of Patent Protections for COVID-19 Vaccines During the Ongoing Pandemic and the Conspiracy Theories: Lights and Shadows of an Issue on the Ground
Full text linkVaccines against the coronavirus disease 2019 (COVID-19) currently constitute the main hope for the fight against the ongoing pandemic. Mass immunization against the severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) should be considered as a global battle in which no country can be left behind, in particular the low-income countries. This last aspect may, in fact, favor the uncontrolled replication of the virus with the insurge of new variants. One of the possible solutions to limit this problem is the waiver of patent protections for COVID-19 vaccines.
On 2 October 2020, India and South Africa asked the World Trade Organization (WTO) to allow all countries to choose to neither grant nor enforce patents and other intellectual property (IP) related to COVID-19 drugs, vaccines, diagnostics and other technologies for the duration of the pandemic, until global herd immunity is achieved.
On 5 May 2021, the United States (US) administration announced the willingness to liberalize intellectual property concerning the COVID-19 vaccines (1, 2).
Although this issue is very interesting, its feasibility is particularly complex and intricate. Accordingly, there are discordant opinions among scholars and physicians on the real usefulness of patent liberalization (3–6). It has been suggested that an exception be made to the agreements establishing the World Trade Organization, in particular The Agreement on Trade Related Aspects of Intellectual Property Rights. This request would be based on the theory according to which the vaccines against the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) during a pandemic should be considered as a “common good”, similarly to water, or air. According to the Economic Theory of the Commons, which is supported by Elinor Ostrom, winner of the 2009 Nobel prize in Economics, the aforementioned terms should be considered in the Roman category of “res communes omnium”, meaning not appropriable and precluded from legal trade (7, 8).
From a practical point of view, the suspension of patent protections would limit the business models for the legitimate producers of COVID-19 vaccines. Among the potential strategies to encourage the waiver of patent protections it is possible to include: the direct donation of vaccines from the high-income countries, the reduction of the costs of the production lines, the shortening of the duration of patent protections, and a series of preferential patent waivers to countries that manufacture a large fraction of the global vaccines (e.g., India). One of the further possible solutions is represented by the solidarity by several governments or other agencies. This strategy is pursued, for example, by the program for COVID-19 Vaccines Global Access (COVAX). The latter is supported by Global Alliance for Vaccines and Immunization (GAVI), Coalition for Epidemic Preparedness Innovations (CEPI), and the World Health Organization (WHO) (9, 10)
Resolution of pinguecula-related dry eye disease after argon laser photocoagulation
Full text linkPurpose: To describe an unusual case of unilateral, chronic symptoms and signs of dry eye, and recurrent episodes of ocular irritation related to pinguecula, which were refractory to prior medical treatments, successfully treated with argon laser photocoagulation. Methods: A 36-year-old man presented with an elevated yellowish mass on his conjunctiva in his left eye, which was associated with dry eye symptoms and general discomfort, such as “tighten-ing sensation” and “stiffness”. On clinical assessment, the left eye revealed a mild conjunctival injection, a fluorescein break-up time (FBUT) of 3.5 s, an abnormal fluorescein staining, and a Schirmer I test of 5 mm. Optical coherence tomography (OCT) imaging evidenced a height at the most elevated point of the pinguecula of 740 μm. The patient underwent argon-laser photocoagulation. Results: After 2 weeks postoperatively, no residual of pinguecula or focal injection of the conjunctiva was detected by slit-lamp biomicroscopy and there was a significant improvement of clinical symptoms and signs: Schirmer I test and FBUT increased to 12 mm and >10 s, respectively, and fluorescein staining was absent. OCT imaging revealed a smooth structure of conjunctival contour, with a height of 404 μm. According to an ex juvantibus line of reasoning, definitive diagnosis was pinguecula-related dry eye disease. Conclusion: Based on the concept that tear film instability and inflammation are two key components of the pathogenesis of dry eye, we coined the term “pinguecula-related dry eye disease,” which can be successfully treated by a complete, accurate removal of the lesion with argon laser photocoagulation
The Bull’s Eye Pattern of the Tear Film in Humans during Visual Fixation on En-Face Optical Coherence Tomography
Full text linkThe aim of the study was to define and characterize the optical behavior of the tear film during visual fixation in humans on en-face optical coherence tomography (OCT). We included 20 healthy participants, 60% female, aged from 25 to 42 years (33.05 ± 4.97 [mean ± SD]) and ten patients with severe dry eye, 50% female, aged from 26 to 42 years (33.7 ± 5.31). To perform high-resolution tear film imaging, participants were asked to gaze at the internal fixation point in the spectral-domain anterior segment OCT device, and meanwhile scanning session was executed at the following time-points after blinking: at the 2 nd , 3 rd , 4 th , 5 th , and 6 th second. After one hour, OCT imaging was repeated (second session) by a different operator masked to the study to verify the reliability of results. During each measuring session, a pulse oximetry was used for continuously measuring the heart rate and oxygen saturation (SpO 2 %). A preliminary experiment was also performed to test the absence of geometric patterns from the anterior surface of a motionless artificial eye. OCT imaging showed a motionless, stable anterior surface of the artificial eye and in dry eye patients. Conversely, in the healthy participants of the study, a bull’s eye pattern of the tear film was detected by OCT at the 2 nd , 3 rd , 4 th , 5 th , and 6 th second after blinking, respectively, in 45%, 60%, 45%, 60%, and 40% of OCT scans during the first session, and in 35%, 65%, 65%, 60%, and 35% of cases in the second session. Overall, a total of 200 OCT scans were performed in normal human population. A significant correlation was found between the novel tear film pattern and heart rate during the first and the second session (p < 0.01) in healthy eyes. Conversely, no correlation was revealed with SpO2%. Intraclass correlation (ICC) analysis for OCT imaging of the tear film revealed a statistically significant reproducibility of the results (ICC = 0.838; p < 0.01), indicating the high level of reliability of the method, independently of heart rate and SpO2% variables. There exists a novel, geometric pattern of the tear film during visual fixation detectable by en-face OCT, which is mainly evident as heart rate increases. Its discovery implies in turn the presence of a specific vibration (or imperceptible motion) of the tear film that, at present, is not recognized and corrected by the OCT software (in image postprocessing) unlike other eyeball movements
Post-mortem corneal thickness measurements with a portable optical coherence tomography system: a reliability study
No full textThe purpose of this study was to determine the repeatability and reproducibility of post-mortem central corneal thickness (CCT) measurements by using a real-time, portable optical coherence tomography (OCT) system on an animal model, and to prospectively evaluate the time-course of post-mortem changes in CCT. Forty-six ocular globes of sheep (Ovis aries) were analyzed with a portable spectral-domain OCT device by two operators at different postmortem intervals (PMIs) as follows: immediately (i.e. within 10 minutes), at the 30(th) minute, at the 1(st), 6(th), 12(th), 24(th) and 48(th) hour, and later (up to the 96(th) hour). The coefficient of repeatability ranged from 0.3% to 3.5%, and coefficients of reproducibility ranged from 0.2% to 3.7% in the central region of the cornea. The intraclass correlation coefficients were particularly high at different PMIs, thus confirming good measurement reliability with the portable OCT. The average CCT decreased immediately and then increased thereafter, with two peaks at 6 and 24 hours after death. Our results suggest that portable OCT is a reliable tool for monitoring CCT variations after death and may be useful in characterizing corneas before explantation, detecting quantitative variations during post-mortem corneal degeneration or assessing changes in CCT for forensic implications
Simultaneous occlusion of three cilioretinal arteries following scleral buckling surgery under local anesthesia
Full text linkBACKGROUND:
Cilioretinal artery (CRA) occlusions are rare in young patients. In these cases, the most commonly associated causes are considered to be the same as those implicated in central retina artery occlusions, such as vasculitic processes, migraine, cardiac disorder, and coagulation abnormality. The aim of this article was to report for the first time the medical records and investigational results of an unusual case of simultaneous occlusion of three CRAs after scleral buckling surgery under local anesthesia.
METHODS:
A complete ophthalmic examination, including color fundus image, fundus fluorescein angiography, optical coherence tomography, visual field, as well as systemic and laboratory assessments, was performed.
RESULTS:
A case of contemporaneous blockage of three CRAs after ab externo surgery for retinal detachment in a 29-year-old Caucasian woman was reported. The interdisciplinary approach and the imaging results have allowed us the clinical definition of such a very rare case.
CONCLUSION:
Here, we reported that optical coherence tomography is an indispensable tool to better delineate the pathological process and follow atrophic changes in the macula, especially in cases in which fundus fluorescein angiography and systemic tests may be poorly informativ
A novel technique of contrast-enhanced optical coherence tomography imaging in evaluation of clearance of lipids in human tears
Full text linkPurpose: The aim of this work was to gather preliminary data in different conditions of healthy eyes, aqueous tear deficient dry eyes, obstructive meibomian gland disease (MGD) and non-obvious obstructive MGD (NOMGD) individuals, using a new, contrast-enhanced optical coherence tomography (OCT) imaging method to evaluate the clearance of lipids in human tears. Methods: Eighty-two adult patients presenting with complaints of ocular irritation were studied for abnormalities of the ocular surface and classified as healthy (n = 21), aqueous tear deficient dry eyes (n = 20), obstructive MGD (n = 15) and NOMGD (n = 26) individuals. A lipid-based tracer, containing an oil-in-water emulsion, was used to obtain an enhanced OCT imaging of the lower tear meniscus. After instillation, a dramatic initial increase of reflectivity of the lower tear meniscus was detected by OCT, followed by a decay back to baseline values over time. Based on this finding, the clearance of lipids was measured in real-time by Fourier-domain anterior segment OCT. Results: The differences in the clearance of lipids among the four groups as well as the correlations between symptom questionnaire score, standardized visual scale test, fluorescein break-up time, ocular surface fluorescein staining score, Schirmer I test scores were found to be statistically significant. The individual areas under the curve of the clearance of lipids calculated by the receiver operating characteristic curve technique ranged from 0.66 to 0.98, suggesting reliable sensitivity and specificity of lipid-enhanced OCT imaging. Conclusions: This new technique of contrast-enhanced OCT imaging of the tear film following lipid-based tracer instillation provides a measure of the clearance of lipids. The quantitative values found are in agreement with other methods of evaluation of the lacrimal system. An improvement of the clinician's ability in the diagnosis and understanding of abnormalities of the ocular surface may be achieved by this simple approach
- …
