Intraocular pressure measurement with ocular response analyzer over soft contact lens

Purpose: To compare intraocular pressure (IOP) measured with ocular response analyzer (ORA) with and without soft contact lenses (CL) on eye. Methods: Goldmann correlated intraocular pressure (IOPg) and corneal compensated intraocular pressure (IOPcc) were measured in 56 eyes of 28 subjects without any ocular pathology, using ORA. One eye was fitted with Narafilcon A (1-Day Acuvue True Eye, Johnson & Johnson) and the other eye with Nelfilcon A (Daily AquaComfort Plus, Ciba Vision), each with −3.00D and IOPg and IOPcc were again measured over CL. The variation in the IOP with and without CL was determined. Results: Out of 28 subjects, 54% (15) were female. Mean age of the subjects was 29.4 ± 9.8 years. Both the IOPg and IOPcc when measured with CL, were found statistically significantly lower than without CL (p < 0.05). In subjects wearing Narafilcon A lens, IOPg and IOPcc were found 0.88 ± 2.04 mmHg and 1.55 ± 2.16 mmHg lower than without CL, respectively. Similarly, with Nelfilcon A lens, IOPg and IOPcc were found to be 1.03 ± 1.93 mmHg and 1.62 ± 3.12 mmHg lower, respectively. IOPcc was highly affected and underestimated by more than 3 mmHg in upto 36% of the subjects. Conclusion: Measurement of IOP over minus (−3.00D) CL with ORA is dependent upon CL properties when measured in normal IOP population. It showed lower IOP over Narafilcon A and Nelfilcon A soft CL in comparison to the pressures measured without lenses. IOPg was found less affected by CL. For the accurate measurement of IOP with ORA, CL should be removed

Effect of soft contact lens wear on tear level and subjective comfort level

Purpose: The purpose of this study was to determine the effect of three months of soft contact lens (CL) wear on Schirmer score and tear break-up time (TBUT). We also evaluated the effect of change in tear level on subjective comfort level. Methods: This was a longitudinal prospective study conducted in normal myopic subjects who had never worn CL before. Schirmer I test and fluorescein TBUT were measured in each subject. Subjects were fitted with a daily disposable (Nelfilcon A or Stenofilcon A) in one eye and a monthly disposable (Lotrafilcon B or Comfilcon A) in the other eye. Level of comfort was subjectively evaluated two times a day (after commencing lens wear and before taking out the lens) every day in a 100 division scale. The average values were used in the analysis. Level of comfort on first month was compared with the comfort on third month. Tear level tests were repeated after three months of lens wear. Results: Schirmer score reduced by 5.8±9.3 mm (p = 0.000) and TBUT reduced by 2.8±7.9 secs (p = 0.009) after three months of CL wear. The changes in Schirmer score and TBUT were not associated with the lens materials (One way ANOVA, p > 0.05). Subjective comfort level during first month and third month remained same (p = 0.272). There was no correlation of tear Schirmer socre and TBUT with subjective comfort level (p > 0.05). Conclusion: Three months of soft contact lens wear reduced tear level; however, it did not reduce the subjective comfort level.info:eu-repo/semantics/publishedVersio

Uso de lentes de contacto : deteriorização das suas propriedades e alterações fisiológicas associadas

Tese de Doutoramento em CiênciasAs lentes de silicone-hidrogel de alta transmissibilidade ao oxigénio foram introduzidas no mercado em 1999 para uso contínuo ou prolongado, tendo desde essa data, vindo a sofrer alterações. Resultados recentes apontam para que as complicações associadas à hipoxia têm vindo a desaparecer e o número de profissionais que optam pelas lentes de silicone-hidrogel começa a aumentar. Este trabalho reúne os resultados de um estudo longitudinal realizado ao longo de um período de 2 anos. Um dos objectivos foi avaliar o comportamento das novas lentes de contacto de silicone-hidrogel sobre a fisiologia da superfície ocular quando usadas em porte diário. Foram utilizadas várias técnicas de observação para uma avaliação tanto subjectiva como objectiva das alterações fisiológicas associadas ao seu uso. Outro objectivo desta tese foi estudar quantitativamente a deterioração das lentes de contacto mediante a avaliação de algumas propriedades das lentes novas e usadas, tais como o índice de refracção, humectabilidade da lente, transmitância, rugosidade da superfície e topografia, e analisar a sua possível relação com as alterações ou complicações fisiológicas. Este estudo pretende combinar a análise de propriedades físico-químicas das lentes de contacto e o comportamento clínico destes materiais. Foram seleccionados 61 novos usuários, aos quais foram realizados vários exames que permitiram avaliar a superfície ocular (córnea, pálpebras e conjuntiva), película lacrimal e sensibilidade visual ao contraste. Aos pacientes foi adaptada uma lente diferente em cada olho para ser usada em porte diário e cada paciente foi observado durante 6 meses. As lentes utilizadas neste estudo foram as lentes de silicone-hidrogel pertencentes à 1ª geração: Purevision™ e Focus Night & Day™; as da 2ª geração: Acuvue® Advance™ e O2Optix™ e também uma lente de hidrogel convencional, Acuvue® que funcionou como lente de controlo. Os exames foram realizados no início e ao fim de 1, 3 e 6 meses. Os resultados apresentados nesta tese mostram que as lentes de silicone-hidrogel não podem ainda ser consideradas completamente biocompatíveis umas vez que ainda provocam interacções indesejáveis com a superfície ocular anterior. Este estudo demonstra também que algumas propriedades físico-químicas das lentes de contacto de silicone-hidrogel e convencional utilizadas neste estudo, sofrem alterações depois de usadas. Este padrão de deterioração ou envelhecimento é distinto nos diferentes materiais, dependendo das suas características.The silicone-hydrogel contact lenses with a high oxygen transmissibility were first introduced in the market in 1999 for continuous wear, and have since this date been altered. Recent results indicate that the complications associated with hypoxia have come to disappeared and the number of professionals whom opt to use the silicone-hydrogel contact lenses has begun to increase. This work present the results of a longitudinal study carried over 2-years period. One of the aims was to evaluate the behaviour of the new silicone-hydrogel contact lenses on the physiology of the ocular surface in a daily wear schedule. Several subjective and objective techniques had been used to evaluate the physiological alterations associated to contact lenses wear. Another aim of this thesis was to study quantitatively the deterioration of the contact lenses by means of the evaluation of some properties, such as refractive index, contact lens wettability, transmittance, surface roughness and topography of the new and worn contact lenses and to analyze their possible relation with the physiological alterations or complications. This study it intends to combine the analysis of physical-chemical properties of the contact lenses and the clinical behaviour of these materials. A group of 61 neophytes was selected and subjected to several examinations that allowed to evaluate the ocular surface (cornea, eyelids and conjunctive), lacrimal film and visual contrast sensitivity to be evaluated. Subjects had worn a different lens in each eye in a daily wear schedule during 6 months. The contact lenses used in this study were the first generation of silicone-hydrogel: Purevision™ and Focus Night & Day™; the second generation: Acuvue® Advance™ and O2Optix™ and also a conventional hydrogel contact lens, Acuvue® was used as the control lens. The examinations had been carried through the beginning and to the end of 1, 3 and 6 months. With this work it was possible to show that the silicone-hydrogel contact lenses still cannot be considered completely biocompatible since they still cause undesirable interactions with the anterior ocular surface. This study also demonstrates that the physico-chemical properties of the silicone-hydrogel and conventional contact lenses used in this study, suffer alterations after wear. This standard of deterioration or aging is distinct in the different materials, depending on its characteristics

Evaluation of inflammatory response induced by different types of daily contact lenses

Introduction: Contact lenses (CL) are biocompatible materials however, CL can also act as a vector for microorganisms to adhere and transfer to the ocular surface. Communal microorganisms that uneventfully cohabitate on lid margins and conjunctiva and potential pathogens that are found transiently on the ocular surface can adhere to CL in vivo. In the presence of reduced tissue resistance, these resident microorganisms or transient pathogens can invade and colonize the cornea or conjunctiva and produce inflammation or infection. Approximately two thirds of the isolated bacteria from CL-associated microbial keratitis are Gram-negative bacterial strains, most notably Pseudomonas aeruginosa but also some Serratia species, while one third comprises Gram-positive cocci, including Staphylococcus aureus and Staphylococcus epidermidi. Purpose: In order to access the inflammatory potential of daily disposable CL, the propose of this study was to evaluate the inflammatory response induced by different types of daily CL before and also after a normal daily wear. The inflammatory response can be measured by quantifying the Tumor Necrosis Factor alpha (TNF-α) produced by macrophages after contact with the CL. The microorganisms that are able to adhere to the CL are the major inducer of a possible inflammatory response, so microbiome of CL after the normal daily wear will also be evaluated. Methods: To establish the best incubation time to evaluate the pro-inflammatory potential of the daily weared CL (8 hours of wear), they were co-incubated with a macrophage cell culture for 3h, 8h and 14h and TNF-α in the supernatant of co-incubation was quantified by ELISA. Macrophage cell viability after co-incubation with CL was also accessed by lactate dehydrogenase (LDH) leakage assay. Results: The results showed that after 3h of co-incubation, only the positive control (containing LPS) showed a significant increase in TNF-α values. After 8h, of co-incubation the weared CL showed a significant increase of four times, while at 14h that increase was only of 2.5 times. Analysis of the LDH showed that at 14h of co- incubation more than 50% of the macrophage cells were death, contrary to 3 and 8 hour of co-incubation that showed viability values above 85%. Conclusion: These results indicated that the best incubation time to test the inflammatory potential of the CL wear 8 hours of co-incubation.info:eu-repo/semantics/publishedVersio

Contrast sensitivity function with soft contact lens wear

Purposes: To compare contrast sensitivity function (CSF) with soft contact lens (SCL) and spectacles wear. To investigate the effect of a three-month period of SCL wear on CSF.Methods: Forty-seven myopic subjects with no history of contact lens (CL) wear were included in this longitudinal prospective study. CSF was measured with spectacles using the CSV-1000 (VectorVision, Greenvile, OH). Subsequently, subjects were fitted with a daily disposable lens (Nelfilcon-A, Stenofilcon-A or Nesofilcon-A) in one eye and a monthly disposable lens (Lotrafilcon-B. Comfilcon-A or Balafilcon-A) in the other eye and wore the same type of CLs for three months. CSF was measured again on the same day and after three months wearing CLs. Differences in CSF with spectacles and CLs on baseline and changes to CSF after three months of CLs wear were assessed. The effect of lens materials and wearing modality on CSF change was also investigated.Results: CSF was higher with CLs in comparison to the values with spectacles for spatial frequencies of 3, 6 and 12 cycles per degree (cpd) (p 0.05). There was no difference in CSF between hydrogel and silicone CLs as well as when comparing daily with monthly wear CLs (p > 0.05).Conclusion: CSF is better with CLs than with spectacles. CSF values with CL are similar between =baseline and after 3 months of lens wear. (C) 2020 Spanish General Council of Optometry. Published by Elsevier Espana, S.L.U.This work was supported by the Portuguese Foundation for Science and Technology (FCT) within the framework of the Strategic Funding UID/FIS/04650/2019

Interactions between contact lenses and lens care solutions: Influence in optical properties

Purpose: Investigate changes in optical properties of contact lenses materials (transmittance and reflectance) and lens care solutions (absorption and fluorescence) resulting from its interaction. Methods: From an experimental study, triplicate measurements of transmittance and reflectance of five contact lenses (Senofilcon A, Lotrafilcon B, Balafilcon A, Comfilcon A, and Omafilcon A), as well as UV-vis absorption and fluorescence of four lens care solutions (LCS) (ReNu MultiPlus, Biotrue, OPTI-FREE PureMoist, and AOSept Plus), were evaluated before and after 8 h, one day and one week in storage. The outcomes were provided by Shimadzu UV3101-PC UV-vis-NIR spectrophotometer equipped with an integrating sphere, between 200-700 nm, and SPEX-Fluorolog 2 FL3-22 spectrofluorometer. Results: All variables exhibited statistically significant differences over time. Comfilcon A showed the lowest ultraviolet radiation (UVR) A & B attenuation. Balafilcon A and Lotrafilcon B displayed a slight suppression of UVR. Senofilcon A was effective in UVR protection and showed less effect on the fluorescence of lens care solutions. Overall, the reflectance decreased after storage (p < 0.05). AOSept Plus absorbance and fluorescence demonstrated lower interactions than multipurpose solutions (MPS), and Lotrafilcon B induced more remarkable changes in optical properties of LCS than the other materials. Conclusion: The findings suggest that optical variables of lens care solutions and contact lenses changed mutually after storage, probably associated with biochemical and biophysical interactions between components and the release of some polymer compounds. These findings can provide additional information about the interaction of CL materials and LCS in clinical behavior.This work was supported by the Portuguese Foundation for Science and Technology (FCT-Portugal) in the framework of the Strategic Funding of CF-UM-UP (UIDB/04650/2020)

In vivo analysis of daily disposable contact lenses wettability

Introduction: Wettability is an important property of contact lens (CL) materials. When a lens has a poor wettability tends to dehydrate more and become uncomfortable for the user. Today there are several contact lenses on the market that incorporate moisturizing agents that target the best comfort and the time of wear. Propose: The aim of this study was to determine “in vivo” wettability of recent daily disposable CL. Methods In this contralateral open trial, 27 subjects (8 males) with mean age of 28.2±7.5 years were randomly fitted with 6 daily disposable CL. The lenses materials used were: Stenfilcon A (Cooper Vision), Delefilcon A (Alcon), Nelfilcon A (Alcon), Narafilcon A (Johnson & Johnson), Nesofilcon A (Bausch & Lomb) and Omafilcon A (Cooper Vision). Patients were followed over a day of CL wear. The principal measurements were the non-invasive break-up time (NIBUT) and pre-lens non-invasive break-up time (PL-NIBUT) assessed 10 minutes (PL-NIBUT1) and 4.4 ± 0.2 hours (PL-NIBUT2) after CL wear. The measurements were made with a Tearscope Plus (Keeler Instruments Ltd, Windsor, UK) with a grid in a room temperature of 21.3±2.5°C. Three measurements for each lens were made and the mean values were compared. Results It was observed a decrease in PL-NIBUT over contact lens wear period. Although the initial NIBUT values were higher than the average values recorded for PL-NIBUT1 and PL-NIBUT2 for each of the lenses tested, there were no significant differences for NIBUT values (p = 0.622), PL-NIBUT1 (p = 0.624) and PL-NIBUT2 (p = 0.631) between the various materials used. The eyes fitted with narafilcon A recorded the largest decrease in the PL-NIBUT decreasing from13.99±4.40 s to 7.91±1.56 s over 4.4 hours of wear. This difference was statistically significant (p = 0.008). Similar results were obtained for nesofilcon A (13.88±4.99 s to 8.27±1.66 s, p=0.008); stenfilcon A (13.36±4.00 s to 9.28±1.70 s, p=0.027) and Omafilcon A (12.99±1.71 s to 9.21±2.09 s, p=0.004). Compared to NIBUT values, the nesofilcon A users revealed a greater reduction in PL-NIBUT1 (after 10 minutes of CL wear) (13.88±4.99 s to 9.72±2.12 s, p = 0.027) and the same behavior was obtained for Omafilcon A material (12.99±1.71 s to 11.06±2.26 s, p = 0.003). Data analysis also revealed no statistically significant differences in PL-NIBUT for patients fitted with the delefilcon A (11.26±3.9 s to 9.12±1.67 s) (p = 0.102) and nelfilcon A (12.77±1.65 s to 9.4±3.81 s) (p = 0.110) throughout the period of use of CL. Conclusion The delefilcon A and nelfilcon A exhibit a greater consistency in the PL-NIBUT values over the 4.4 hours of lenses wear. The incorporation of PVA (polyvinyl alcohol) may have a beneficial effect on the stability of the tear film. However, studies with a larger sample size are needed to confirm these results and to associate with subjective comfort.info:eu-repo/semantics/publishedVersio

Evaluación de la transmitancia en lentes de contacto con diferentes potencias

[Extracto] Justificación y objetivos - Cuando la luz atraviesa cualquier material absorbente, su intensidad disminuye y esta variación puede ser dependiente de factores como la potencia, la espessura y el coeficiente de absorción del material de la lente de contacto (LC). Evaluación de la influencia de la potencia en la transmitancia de lentes de contacto , en diferentes regiones del espectro electromagnético: Visible (400-700 nm), UVA (315-400 nm), UVB (280-315 nm) y UVC (230-280 nm). [...]info:eu-repo/semantics/publishedVersio