The Need for Ocular Protection for Health Care Workers During SARS-CoV-2 Outbreak and a Hypothesis for a Potential Personal Protective Equipment.

SARS-CoV-2 is a coronavirus with high infectivity and has caused dramatic pressure on health systems all over the world. Appropriate personal protection for medical staffs is critical. For ocular protection, there is ongoing hot debate and concern for potential ocular transmission of SARS-CoV-2. Ocular manifestations and positive detection of viral RNA in ocular samples were only reported in very small number of patients infected with SARS-CoV-2. However, health care workers need to face patients more closely and have higher risk of aerosol contamination. Thus, appropriate ocular protection for medical workers is still recommended by organizations such as WHO and American Academy of Ophthalmology. Although eye goggles provide excellent protection and are mandatory for medical practitioners with high risk of exposure, they are not ideal for common clinical practice, because they can disturb vision due to extensive formation of water droplets and frequently cause moderate to severe discomfort after longtime wearing, which have been reported to interfere with working status. For the majority of medical workers who don't deal with high risk patients, they are not advised to wear goggles in daily practice. However, they also face the risk of infection due to the presence of asymptomatic carriers. Especially in situations with high risk of ocular exposure, such as close physical examination, eye surgery, dental clinics and surgery, ocular protection may be needed. Griffithsin has been shown to directly bind to spike proteins and has anti-viral activity against a broad spectrum of viruses, including coronavirus. Griffithsin is found to inhibit the entry of SARS-CoV at relatively low concentration and is stable and non-toxic. SARS-CoV-2 and SARS-CoV share the same entry receptors and their spike proteins are similar in conformation. We hypothesize that contact lenses containing nanoparticles loaded with griffithsin may provide sufficient ocular protection for medical staffs without high risk of exposure during the outbreak period of SARS-CoV-2. If proven effective, griffithsin-loaded contact lens can be considered as a supplementary ocular protective equipment for medical workers who can tolerate well. The daily disposable contact lens should be applied as needed and refrain from extended wearing in order to reduce potential side effects.

Ocular Drug Delivery Systems Using Contact Lenses.

The use of contact lenses as ocular drug delivery systems has been considered intuitive for decades. However, at this time, there are no approved products using such systems. In this article, we review the challenges with current therapies, pharmacokinetics, and pharmacodynamics of different drug classes and the patient population. In addition, we note the relative lack of clinical studies, and list potential products in active development at this time. In particular, we address the alignment of time course of the therapeutic need, the pharmacokinetics of the molecule, and the delivery characteristics of the systems (e.g., pulsatile vs. zero-order). We also discuss the needs of various populations including the elderly (who may have motor and cognitive issues as well as presbyopia) and the young. While a contact lens delivery system may also provide refractive correction, to date, most of the studies have used noncorrective (plano) lenses. We also considered nanotechnology-based carrier systems. We generalize the development of contact lens delivery systems to all ocular delivery systems in which there are relatively few product approvals and long development times.

The COVID-19 pandemic: Important considerations for contact lens practitioners.

A novel coronavirus (CoV), the Severe Acute Respiratory Syndrome Coronavirus - 2 (SARS-CoV-2), results in the coronavirus disease 2019 (COVID-19). As information concerning the COVID-19 disease continues to evolve, patients look to their eye care practitioners for accurate eye health guidance. There is currently no evidence to suggest an increased risk of contracting COVID-19 through contact lens (CL) wear compared to spectacle lens wear and no scientific evidence that wearing standard prescription spectacles provides protection against COVID-19 or other viral transmissions. During the pandemic there will potentially be significant changes in access to local eyecare. Thus, it is imperative CL wearers are reminded of the steps they should follow to minimise their risk of complications, to reduce their need to leave isolation and seek care. Management of adverse events should be retained within optometric systems if possible, to minimise the impact on the wider healthcare service, which will be stretched. Optimal CL care behaviours should be the same as those under normal circumstances, which include appropriate hand washing (thoroughly with soap and water) and drying (with paper towels) before both CL application and removal. Daily CL cleaning and correct case care for reusable CL should be followed according to appropriate guidelines, and CL exposure to water must be avoided. Where the availability of local clinical care is restricted, practitioners could consider advising patients to reduce or eliminate sleeping in their CL (where patients have the appropriate knowledge about correct daily care and access to suitable lens-care products) or consider the option of moving patients to daily disposable lenses (where patients have appropriate lens supplies available). Patients should also avoid touching their face, including their eyes, nose and mouth, with unwashed hands and avoid CL wear altogether if unwell (particularly with any cold or flu-like symptoms).

Continuous intraocular pressure monitoring in patients with obstructive sleep apnea syndrome using a contact lens sensor.

PURPOSE: To analyse nocturnal intraocular pressure (IOP) fluctuations in patients with obstructive sleep apnea syndrome (OSAS) using a contact lens sensor (CLS) and to identify associations between the OSAS parameters determined by polysomnographic study (PSG) and IOP changes. METHOD: Prospective, observational study. Twenty participants suspected of having OSAS were recruited. During PSG study, IOP was monitored using a CLS placed in the eye of the patient. The patients were classified according to the apnea-hypopnea index (AHI) in two categories, severe (>30) or mild/moderate (<30) OSAS. We evaluated several parameters determined by the IOP curves, including nocturnal elevations (acrophase) and plateau times in acrophase (PTs) defined by mathematical and visual methods. RESULTS: The IOP curves exhibited a nocturnal acrophase followed by PTs of varying extents at which the IOP remained higher than daytime measurement with small variations. We found significant differences in the length of the PTs in patients with severe OSAS compared to those with mild/moderate disease (P = 0.032/P = 0.028). We found a positive correlation between PTs and OSAS severity measured by the total number of apneic events (r = 0.681/0.751 P = 0.004/0.001) and AHI (r = 0.674/0.710, P = 0.004/0.002). Respiratory-related arousal and oxygen saturation also were associated significantly with the IOP PT length. CONCLUSIONS: Periods of nocturnal IOP elevation lasted longer in severe OSAS patients than those with mild/moderate OSAS and correlate with the severity of the disease. The length of the nocturnal PT is also associated to respiratory parameters altered in patients with OSAS.

Estrategia socioeducativa para la familia en el uso de la tecnología sanitaria del lente de contacto / Socio-educative strategy for the family in the use of the sanitary technology of the contact lens

La Estrategia socioeducativa para la familia en el uso de la tecnología sanitaria del lente de contacto, proyecto de investigación del cual derivan los resultados que se exponen en el presente texto; se instituye a partir de un nuevo algoritmo de trabajo por el optometrista, atendiendo a que con la terapéutica encaminada a contrarrestar las complicaciones que ocasiona el uso indebido de la tecnología se ha intentado minimizar las anomalías de enfermedades oculares. Su objetivo general se dirige a un estudio social sobre la innovación, desde la perspectiva de las relaciones ciencia, tecnología y sociedad. El proyecto tiene carácter de innovación tecnológica de tipo Investigación aplicada. Sus resultados validan, desde un enfoque interdisciplinario, las influencias que cada contexto sociocultural ejerce sobre el desarrollo de la ciencia y la tecnología y los impactos sociales(AU)

La The socio-educative strategy for the family in the use of the sanitary technology of the contact lens, research project from which derive the results that are exhibited in the present text; it is instituted from a new work algorithm by the optometrist, attending to that with the therapeutics directed to resist the complications that the undue use of the technology causes, it has tried to minimize the anomalies of ocular illnesses. Its general objective goes to a social study on the innovation, from the perspective of the relations science, technology and society. The project has character of technological innovation of type Applied Investigation. Its results validate, from an interdisciplinary approach, the influences that every sociocultural context exercises on the development of the science and the technology and the social impacts(AU)

Scleral contact lens thickness profiles: The relationship between average and centre lens thickness.

PURPOSE: To develop a methodology to reliably determine the thickness profile of scleral contact lenses and examine the relationship between the centre and average lens thickness for a range of lens designs and back vertex powers. METHODS: High-resolution images of 37 scleral trial lenses (Epicon LC, Rose K2 XL and ICD 16.5) were captured using an optical coherence tomographer, and their thickness profiles were generated after correcting for known measurement artefacts. Centre lens thickness values were compared with manual lens gauge measurements, and repeatability was assessed by comparing average thickness values derived from orthogonal meridians of each lens. RESULTS: The imaging technique displayed a high level of agreement with a manual lens gauge for centre thickness measurements; mean difference 5 ±â€¯9 µm (95% LoA -14 to +23 µm), and a very high level of repeatability; mean difference between orthogonal meridians 1 ±â€¯3 µm (95% LoA -6 to +8 µm). Lens thickness profiles varied between lens designs, with distance from the lens centre, and with back vertex power. Increasing back vertex powers resulted in a significant over or underestimation (up to 33% for high minus powers) of the average lens thickness based on the centre lens thickness. CONCLUSIONS: The thickness of scleral contact lenses varies with distance from the lens centre and the back vertex power. The average lens thickness value derived from the entire lens provides a more appropriate representation of the true lens thickness and should be used in the calculation of scleral lens oxygen transmissibility.

Power Profiles and In Vitro Optical Quality of Scleral Contact Lenses: Effect of the Aperture and Power.

OBJECTIVE: To assess the power profile and in vitro optical quality of scleral contact lenses with different powers as a function of the optical aperture. METHODS: The mini and semiscleral contact lenses (Procornea) were measured for five powers per design. The NIMO TR-1504 (Lambda-X) was used to assess the power profile and Zernike coefficients of each contact lens. Ten measurements per lens were taken at 3- and 6-mm apertures. Furthermore, the optical quality of each lens was described in Zernike coefficients, modulation transfer function, and point spread function (PSF). A convolution of each lens PSF with an eye-chart image was also computed. RESULTS: The optical power fluctuated less than 0.5 diopters (D) along the optical zone of each lens. However, the optical power obtained for some lenses did not match with its corresponding nominal one, the maximum difference being 0.5 D. In optical quality, small differences were obtained among all lenses within the same design. Although significant differences were obtained among lenses (P<0.05), these showed small impact in the image quality of each convolution. CONCLUSIONS: Insignificant power fluctuations were obtained along the optical zone measured for each scleral lens. Additionally, the optical quality of both lenses has showed to be independent of the lens power within the same aperture.

Survey to Determine Perceptions and Practices in Contact Lens Use and Identify Key Features of Safe Use Education

Objectives: To identify consumers' tendencies regarding contact lens (CL) use in order to develop recommendations for messages to include in education for safe CL use and in public awareness campaigns. Materials and Methods: Subjects living in Ankara, Turkey who used eyeglasses and/or contact lenses due to refractive error were included in the study. CL users' reasons for choosing CLs for vision correction, CL-related problems they encountered, and their perceptions regarding safe CL use education and regular ophthalmologic follow-up visits were evaluated using a survey completed by 917 participants. Results: In total, 836 survey forms were included in the analysis. Most of the participants were female (59.6%), university students (91.4%), and 18-30 years old (68.9%). According to the survey results, 64.6% of eyeglass users stated that they had never tried CLs, while 17.7% reported using CLs regularly. Most of the participants (61.7%) said they visit an ophthalmologist only when they needed, while 33.1% claimed to attend regular follow-up. When all participants were considered, the level of satisfaction with glasses was 3.11 out of 5, while CL users reported satisfaction of 4.15 out of 5. Most (78.6%) of the CL users said they started using CL by their own initiative, most commonly due to a dislike of eyeglasses. The most frequent complaint from CL users was dry eye and discomfort in the evening. The most common source of CL use education was ophthalmologists (55.5% of the participants), followed by opticians (28.2%). Conclusion: Incorrect and inappropriate information on CL usage may lead to problems that can threaten eye health. The results of our study suggest that providing accurate information through concise messages in physician-supervised education and raising awareness through the media may be beneficial to public health. Therefore, we identified messages about CL usage and quality of life, safety, and the rules for proper use.

On the power profiles of contact lenses measured with NIMO TR1504 / Perfiles de potencia de las lentes de contacto medidas con NIMO TR1504

No disponible

Comparison of Contact Lens Corrected Quality of Vision and Life of Keratoconus and Myopic Patients.

PURPOSE: To compare and analyze changes in vision quality, subjective symptoms, and psycho-social satisfaction in keratoconus and myopic patients following the wearing of contact lenses. METHODS: This study enrolled 25 keratoconus and 25 myopic patients with corrected vision over 0.8 according to the Snellen chart due to treatment with contact lenses. Patients were surveyed prior to the wearing of contact lenses, and again after three months of contact lens usage with a questionnaire about quality of vision and life. The changes in visual function, visual symptoms, and psycho-social well-being before and after contact lens usage were analyzed. RESULTS: The keratoconus patients' overall degree of satisfaction was higher than the overall degree of satisfaction of myopic patients, and the motivation for contact lens usage and purpose of contact lens treatment were different in the two groups. Keratoconus patients experienced greater changes in satisfaction, particularly in satisfaction during night activities, short-distance work, and the reading of fine print. Furthermore, they experienced fewer dry eye symptoms but greater foreign body sensations than patients with myopia following treatment with contact lenses. No statistically significant differences in social role functions existed between the two groups. Keratoconus patients had a lower expectation of visual acuity recovery before treatment with contact lenses (Mann-Whitney U-test, p = 0.049) compared to myopic patients, and more anxiety about vision loss following treatment (Wilcoxon signed-rank test, p = 0.018) compared to their level of anxiety about vision loss before treatment with contact lenses. CONCLUSIONS: Although the same treatment was applied, keratoconus and myopic patients experienced different types of discomfort and areas of improvement in contact lens corrected vision. Therefore, not only corrected vision, but also subsequent improvement and discomfort outcomes should be considered by patients when choosing contact lens treatment. For patients with mild keratoconus, contact lens treatment may be an efficacious first treatment modality.

[Contact lens care and maintenance]. / Surveillance, hygiène et entretien des lentilles de contact.

All contact lenses with replacement schedules longer than daily must be maintained. At each step of their use, the lenses may be contaminated. Contact lens solutions perform the essential functions of cleaning, decontaminating and preserving the lenses to prevent infectious problems and improve wearing comfort. Contact lens contamination essentially comes from hands, cleaning solutions, cases, water and the environment. The pathogenic microorganisms are mainly Gram-negative bacteria, fungi and amoebae. Contact lens deposits may or may not have an organic origin. Their presence increases the risk of infection because they serve as a nutrient matrix for microbes, and they are responsible for wearing discomfort. Contact lens solutions differ in their composition, their mechanism of action and the concentration of the various agents. To prescribe the best lens care system to each wearer and for each material, it is necessary to be very familiar with them. Maintenance is the main cause of discomfort with contact lenses, either through improper use, solution-material incompatibility, or a reaction of the wearer to the components.

[The search for electrophysiological predictors of visual comfort after presbyopia correction with contact lenses]. / Recherche d'indices électrophysiologiques de confort visuel après correction de la presbytie par lentilles de contact.

Starting at 40 years of age, prespyopia affects a quarter of the world population. Many techniques of presbyopia surgery have emerged in recent years. The purpose of this study was to compare monovision and multifocality and to identify clinical and electrophysiological predictive markers of visual comfort for each correction available in clinical practice. Ten presbyopic patients participated in this study. Patients received monovision and multifocal correction using contact lenses for three weeks each in a random order. A clinical evaluation (visual acuity, TNO test, binocular contrast sensitivity and quality of vision questionnaires) and an electrophysiological evaluation (monocular and binocular pattern VEP with multiple spatial frequencies: 60, 30 and 15') were performed before and after each correction modality. The P100 was significantly wider and slightly earlier after binocular compared to monocular stimulation at T0. The TNO stereopsis score decreased significantly after correction. No other significant differences, either on clinical or electrophysiological criteria, were found between the two modes of correction. Several significant correlations were found between the stereoacuity difference depending upon correction and evoked potentials by binocular pattern at T0. The larger the stereoacuity difference (better stereoacuity with multifocal compensation), the longer the latency of the P100 using 60' checks (R=0.82; P=0.004) and the greater the amplitude of the N75 using 30' (R=0.652; P=0.04). Our study found no differences between the 2 types of correction, but it highlights a benefit of VEP used in current practice and measurement of the P100 wave, the best indicator of stereopsis and the most consistent, to predict visual comfort after compensation presbyopia.

Design and analysis of Bayesian adaptive crossover trials for evaluating contact lens safety and efficacy.

A crossover study, also referred to as a crossover trial, is a form of longitudinal study. Subjects are randomly assigned to different arms of the study and receive different treatments sequentially. While there are many frequentist methods to analyze data from a crossover study, random effects models for longitudinal data are perhaps most naturally modeled within a Bayesian framework. In this article, we introduce a Bayesian adaptive approach to crossover studies for both efficacy and safety endpoints using Gibbs sampling. Using simulation, we find our approach can detect a true difference between two treatments with a specific false-positive rate that we can readily control via the standard equal-tail posterior credible interval. We then illustrate our Bayesian approaches using real data from Johnson & Johnson Vision Care, Inc. contact lens studies. We then design a variety of Bayesian adaptive predictive probability crossover studies for single and multiple continuous efficacy endpoints, indicate their extension to binary safety endpoints, and investigate their frequentist operating characteristics via simulation. The Bayesian adaptive approach emerges as a crossover trials tool that is useful yet surprisingly overlooked to date, particularly in contact lens development.

Ready for action / Listos para la acción

No disponible

The measurement of intraocular pressure over positive soft contact lenses by rebound tonometry / Medición de la presión intraocular sobre lentes de contacto blandas positivas, mediante tonometría de rebote

Purpose: To investigate if the accuracy of intraocular pressure (IOP) measurements using rebound tonometry over disposable hydrogel (etafilcon A) contact lenses (CL) is affected by the positive power of the CLs. Methods: The experimental group comprised 26 subjects, (8 male, 18 female). IOP measurements were undertaken on the subjects’ right eyes in random order using a Rebound Tonometer (ICare). The CLs had powers of +2.00D and +6.00D. Measurements were taken over each contact lens and also before and after the CLs had been worn. Results: The IOP measure obtained with both CLs was significantly lower compared to the value without CLs (t test; p<0.001) but no significant difference was found between the two powers of CLs. Conclusions: Rebound tonometry over positive hydrogel CLs leads to a certain degree of IOP underestimation. This result did not change for the two positive lenses used in the experiment, despite their large difference in power and therefore in lens thickness. Optometrists should bear this in mind when measuring IOP with the rebound tonometer over plus power contact lenses (AU)

Objetivo: Investigar si la precisión de las mediciones de la presión intraocular (PIO), utilizando la tonometría de rebote sobre las lentes de contacto (LC) desechables de hidrogel (etafilcon A), se ve afectada por la potencia positiva de dichas lentes. Métodos: El grupo experimental incluyó a 26 sujetos, (8 varones, 18 mujeres). Se realizó la medición de la PIO en los ojos derechos de los sujetos, de modo aleatorio, utilizando un Tonómetro de Rebote (ICare). Las LC tenían potencias de +2,00D y +6,00D. Se realizaron mediciones con cada lente de contacto, y también antes y después a su uso. Resultados: El valor de la PIO obtenido con ambas LC fue considerablemente menor al valor sin LC (t del test; p<0,001), aunque no se halló una diferencia significativa entre las dos potencias de las lentes. Conclusiones: La tonometría de rebote sobre las LC positivas de hidrogel origina un cierto grado de subestimación del PIO. Este resultado no sufrió variación entre las dos lentes positivas utilizadas en el experimento, a pesar de la gran diferencia de potencia, y por tanto del espesor de las lentes. Los optometristas deberían de tener en cuenta estos resultados en a la hora de medir el PIO con un tonómetro de rebote, con lentes de contacto de mayor potencia (AU)

Reliability of power profiles measured on NIMO TR1504 (Lambda-X) and effects of lens decentration for single vision, bifocal and multifocal contact lenses / Fiabilidad de los perfiles de potencia medidos con NIMO TR1504 (Lambda-X), y efectos del descentramiento de las lentes monofocales, bifocales y multifocales

Purpose: To evaluate the repeatability of power profiles measured on NIMO TR1504 (Lambda-X, Belgium) and investigate the effects of lens decentration on the power profiles for single vision (SV), bifocal (BF) and multifocal (MF) contact lenses. Methods: Accuracy of the sphere power was evaluated using single vision BK-7 calibration glass lenses of six minus and six plus powers. Three SV and four BF/MF contact lenses - three lenses each, were measured five times to calculate the coefficients of repeatability (COR) of the instrument. The COR was computed for each chord position, lens design, prescription power and operator. One lens from each type was measured with a deliberate decentration up to ±0.5mm in 0.1mm steps. Results: For all lenses, the COR varied across different regions of the half-chord position. In general, SV lenses showed lower COR compared to the BF/MF group lenses. There were no noticeable trends of COR between prescription powers for SV and BF/MF lenses. The shape of the power profiles was not affected when lenses were deliberately decentered for all SV and PureVision MF lenses. However, for Acuvue BF lenses, the peak to trough amplitude of the power profiles flattened up to 1.00D. Conclusion: The COR across the half-chord of the optic zone diameter was mostly within clinical relevance except for the central 0.5mm half-chord position. COR were dependent on the lens type, whereby BF/MF group produced higher COR than SV lenses. The effects of deliberate decentration on the shape of power profiles were pronounced for lenses where the profiles had sharp transitions of power (AU)

Objetivo: Evaluar la repetibilidad de los perfiles de potencia medidos con NIMO TR1504 (Lambda-X, Bélgica) e investigar los efectos del descentramiento de las lentes sobre los perfiles de potencia de las lentes de contacto monofocales (SV) bifocales (BF) y multifocales (MF). Métodos: Se evaluó la exactitud de la medida de la potencia esférica utilizando lentes de vidrio monofocales de calibración BK-7, con lentes de seis potencias positivas y seis potencias negativas. Se realizaron cinco mediciones en tres muestras de cada una de las tres lentes monofocales y cuatro lentes bifocales/multifocales diferentes, para calcular los coeficientes de repetibilidad (COR) del instrumento. Se calculó el COR para cada posición de la cuerda, diseño de la lente, prescripción de potencia, y operador. Se midió una lente de cada tipo con un descentramiento deliberada de hasta ±0,5mm, en intervalos de 0,1mm. Resultados: Para todas las lentes, el COR reflejó variaciones en las diferentes regiones de la posición de media cuerda. En general, las lentes monofocales reflejaron un COR menor en comparación a las lentes del grupo BF/MF. No se produjeron variaciones notorias del COR entre las prescripciones de potencia de las lentes monofocales y bifocales/multifocales. La forma de los perfiles de potencia no se vio afectada al descentrar deliberadamente todas las lentes monofocales y PureVision MF. Sin embargo, para lentes Acuvue BF, la amplitud entre el punto más alto y el más bajo de los perfiles de potencia reflejó un aplanamiento de hasta 1,00D. Conclusión: El COR a lo largo de la cuerda media del diámetro de la zona óptica se mostró dentro de la relevancia clínica, excepto en la posición central de la cuerda media de 0,5mm. Los COR dependieron del tipo de lente, reflejando el grupo de lentes bifocales/multifocales un COR superior al de las lentes monofocales. Los efectos del descentramiento deliberado en la forma de los perfiles de potencia fueron significativos en aquellas lentes en las que dichos perfiles tenían unas transiciones de potencia más abruptas (AU)

Developments in contact lens measurement: A comparative study of industry standard geometric inspection and optical coherence tomography.

PURPOSE: The aim of this study was to compare a developmental optical coherence tomography (OCT) based contact lens inspection instrument to a widely used geometric inspection instrument (Optimec JCF), to establish the capability of a market focused OCT system. METHODS: Measurements of 27 soft spherical contact lenses were made using the Optimec JCF and a new OCT based instrument, the Optimec is830. Twelve of the lenses analysed were specially commissioned from a traditional hydrogel (Contamac GM Advance 49%) and 12 from a silicone hydrogel (Contamac Definitive 65), each set with a range of back optic zone radius (BOZR) and centre thickness (CT) values. Three commercial lenses were also measured; CooperVision MyDay (Stenfilcon A) in -10D, -3D and +6D powers. Two measurements of BOZR, CT and total diameter were made for each lens in temperature controlled saline on both instruments. RESULTS: The results showed that the is830 and JCF measurements were comparable, but that the is830 had a better repeatability coefficient for BOZR (0.065mm compared to 0.151mm) and CT (0.008mm compared to 0.027mm). Both instruments had similar results for total diameter (0.041mm compared to 0.044mm). CONCLUSIONS: The OCT based instrument assessed in this study is able to match and improve on the JCF instrument for the measurement of total diameter, back optic zone radius and centre thickness for soft contact lenses in temperature controlled saline.