scholarly journals REPRODUCIBILITY OF MEASUREMENTS OF PRE-CONTACT LENS TEAR FILM KINETICS UNDER NORMAL AND ADVERSE ENVIRONMENTAL CONDITIONS

2021 ◽  
Vol 5 (1) ◽  
pp. e11-e18
Author(s):  
Michel Guillon ◽  
Kishan Patel ◽  
Ruchi Gupta ◽  
Trisha Patel ◽  
Cecile A. Maissa
Keyword(s):  
Contact Lens ◽  
Environmental Conditions ◽  
Contact Lenses ◽  
Tear Film ◽  
Digital Videos ◽  
Measurement Variability ◽  
Non Invasive ◽  
Parallel Group ◽  
The Mean ◽  
Adverse Environmental Conditions

Objectives: To evaluate the reproducibility of tear film kinetics (TFK) measurements during the full interblink period in habitual wearers of delefilcon A daily disposable contact lenses under different environmentalconditions.Methods: Two independent studies were performed, one involving 90 eyes measurements in 49 subjects and the second involving 58 eyes measurements in 32 subjects, after 3 hours of conventional wear in normal environmental conditions (NEC) and an additional 3 hours of computer use under adverse environmental conditions (AEC), defined as 20% relative humidity (RH). Digital videos were obtained by non-invasive Tearscope illumination, followed by a parallel-group post-hoc comparative analysis by masked investigators of the videos obtained during the two studies. Parameters analyzed included non-invasive break-up time (NIBUT); dehydration speed (DS) between the initial break and the spontaneous blink, and minimum protected area (MPA) of the lens surface by the tear film.Results: After 3 hours of wear in normal environmental conditions, the overall population (n=148) had a mean NIBUT of 7.1 ± 7.0 sec, a mean DS of 0.28 ± 0.66 mm2/sec, and a mean MPA of 93.4 ± 16.6%. After an additional 3 hours in AEC, mean NIBUT was 8.4 ± 9.8 mm2/sec, mean DS was 0.26 ± 0.75 mm2/sec, and MPA was 95.2 ± 14.0%. The TFK characteristics in the two studies were similar for each environmental condition: after 3 hours of conventional wear, the mean [95% CI] differences between the two studies were −0.9 [−3.2, +1.4] sec for NIBUT, 0.00 [−0.22, +0.22] mm2/s for DS, and 2.0 [−3.5, +7.4] % for MPA; after an additional 3 hours of wear in 20% RH, the mean [95% CI] differences between the two studies were −1.3 [−4.5, +1.9] sec for NIBUT, −0.03 [−0.28, +0.22] mm2/s for DS and −0.3 [−4.9, +4.3] % for MPA. Conclusions: This analysis showed that the measurement of pre-contact lens TFK carried out in two differ-ent studies involving habitual wearers of delefilcon A having worn their contact lenses for an initial 3 hours under NEC and a further 3 hours under low (20%) hygrometry (AEC) produced similar on-eye wettability, including a long NIBUT, slow DS following the initial break, and wide MPA at the next blink. The results establish the reproducibility of the measurement of pre-contact lens TFK using the Tearscope; by quantifying the measurement variability, the data makes it possible to carry out precise sample size calculations in future studies involving pre-contact lens TFK measurements to quantify on-eye wettability under both normal and adverse environmental low (20% RH) hygrometric conditions.

scholarly journals WETTABILITY – ANOTHER PARAMETER FOR GOOD FITTING OF A SILICONE-HYDROGEL DAILY DISPOSABLE CONTACT LENS

2019 ◽  
Vol 31 (4) ◽  
pp. 1001-1004
Author(s):  
Nikola Peev
Keyword(s):  
Contact Lens ◽  
Contact Lenses ◽  
Tear Film ◽  
The United States ◽  
Modern World ◽  
Silicone Hydrogel ◽  
Non Invasive ◽  
The World ◽  
Silicon Hydrogel

The modern world is very fast and dynamic. Consumer requirements rise to every commodity part of their everyday life - food, clothing, cosmetics, and medical devices. Eye care and eye health are also part of them. Companies producing contact lenses work daily to improve the safety and comfort of wearing, as well as on the technical characteristics of the material (type of material, wear time, module, Dk / t etc.). Silicon hydrogel contact lenses (SiHy) were introduced almost two decades ago. At that time it was estimated that there are about 70 million contact lenses all over the world. Since then, their number has doubled and a significant majority now have silicone-hydrogel contact lenses, resulting in a steady and noticeable reduction in the number of regular hydrogel lenses. When the first one-day silicon-hydrogel contact lenses were introduced in 2008, they were announced as breakthroughs in technology. When they were introduced to the market, they were presented in spherical, toric and multifocal designs, which led to a significant increase in the use / prescription of silicon-hydrogel daily disposable contact lenses. A survey conducted in 2014 by the International Consortium illustrates this point. Although, according to this study, the use of SiHy contact lenses varies widely across the world. In the United States, Canada, Australia and the United Kingdom, four to six times more patients were fitted with silicone-hydrogel CLs compared to hydrogels in 2014 and in each country, daily disposable SiHy contact lenses were prescribed with a larger frequency compared to daily disposable hydrogel lenses. It is important to make a good fit to ensure and increase the comfort of wearing contact lenses. In addition to some of the standard fitting techniques such as: keratometry and choice of base curve of the lens; size and eccentricity; an assessment of the mobility of a lens placed in the eye - look positions, mobility, push up test, can be added and the wetting of the contact lens. Even in perfect fit, if the lens does not interact well with the tear film, it would lead to complaints and discomfort in the patient. The degree of wetting is determined by the balance between adhesive and cohesive forces acting on the surface of the lens. CLs, which can support full wetting, allow a tight coating of the tear film, a smooth recovery of the tear layer after eyelid opening and good visual acuity. The interaction between CL, eye surface and tear film is vital to their successful fit. It has long been known that both the organic and inorganic components of the tear film and anterior surface of the eye can deposit deposits on the contact lenses. There are various non-invasive methods for assessing the tear film and, above all, the lipid layer. Some of these are Non invasive breakup time (NIBUT) and specular biomicroscopy. In the present work we will look at daily disposable silicone-hydrogel contact lenses that have been tested in vivo for good wetting, stability and good regeneration of the tear film.

Inflammatory status predicts contact lens discomfort under adverse environmental conditions

2020 ◽  
Vol 18 (4) ◽  
pp. 829-840
Author(s):  
Itziar Fernández ◽  
Alberto López-Miguel ◽  
Vicente Martín-Montañez ◽  
Amalia Enríquez-de-Salamanca ◽  
Margarita Calonge ◽  
...  
Keyword(s):  
Contact Lens ◽  
Environmental Conditions ◽  
Inflammatory Status ◽  
Adverse Environmental Conditions

scholarly journals Clinical Performance of Toris K Contact Lens in Patients with Moderate to Advanced Keratoconus: A Real Life Retrospective Analysis

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Ihsan Yilmaz ◽  
Ferah Ozcelik ◽  
Berna Basarir ◽  
Gokhan Demir ◽  
Gonul Durusoy ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Contact Lens ◽  
Contact Lenses ◽  
Clinical Performance ◽  
Real Life ◽  
Soft Contact Lenses ◽  
Corrected Visual Acuity ◽  
Uncorrected Visual Acuity ◽  
Central Cone ◽  
The Mean

Objectives.To evaluate the visual performance of Toris K soft contact lenses in patients with moderate-to-advanced keratoconus and also to compare the results according to cone types, cone location, and severity of keratoconus.Materials and Methods.Sixty eyes of 40 participants were included in this retrospective study. Uncorrected visual acuity (UCVA), best-spectacle corrected visual acuity (BCVA), best-contact lens corrected visual acuity (BCLCVA), and comfort rating via visual analogue scales (VAS) were measured.Results.The mean age was 27.3 ± 8.6 years (range: 18 to 54). The mean logMAR UCVA, BCVA, and BCLCVA were 0.85 ± 0.38 (range: 0.30–1.30), 0.47 ± 0.27 (range: 0.10–1.30), and 0.16 ± 0.20 (range: 0–1.00). There were significant increases in visual acuities with contact lenses (p<.05). BCLCVA was significantly better in oval type than globus type (p=.022). UCVA and BCLCVA were significantly better in moderate keratoconus group (p=.015,p=.018). The mean line gain in Snellen was 3.6 ± 1.8 lines (range: 0–7 lines). The mean line gain was higher in central cone group than paracentral cone group and oval group than globus group (p=.014,p=.045). The mean VAS score was 8.14 ± 1.88 (range: 6–10).Conclusions.Toris K can improve visual acuity of patients with keratoconus. Toris K is successful even in the moderate and advanced form of the disease.

scholarly journals Morphological and Functional Assessment of Meibomian Glands in Keratoconus

2021 ◽  
Author(s):  
Ömür Ö Uçakhan ◽  
Gökçen Özcan
Keyword(s):  
Ocular Surface ◽  
Tear Film ◽  
Early Screening ◽  
Ocular Surface Disease Index ◽  
Non Invasive ◽  
The Mean ◽  
Meibomian Glands ◽  
Break Up ◽  
And Function ◽  
Corneal Staining

Abstract Purpose: To evaluate the morphology and function of the meibomian glands (MG) in keratoconus patients.Methods: One hundred eyes of 100 keratoconus patients and 100 eyes of 100 age-matched healthy subjects were included into this study. Ocular Surface Disease Index (OSDI) scores, non-invasive break up time (NIBUT), meibography findings, fluorescein staining of the ocular surface, tear film break-up time (TBUT), and Schirmer I test were recorded in all patient eyes and were compared with controls.Results: The mean TBUT and NIBUT were significantly lower, corneal staining and OSDI scores were statistically higher in the keratoconus group (p<0.05). The mean meiboscore, partial gland, gland dropout and gland thickening scores of the upper and lower eyelids were significantly higher in keratoconus patients compared to controls (p<0.05). The NIBUT measurements significantly correlated with MG loss in both upper and lower eyelids (p<0.05). The severity of keratoconus seemed to correlate with meiboscore, partial gland, gland thickening scores in both upper and lower eyelids. Conclusion: Our data suggest that corneal ectasia in keratoconus is associated with alterations in ocular surface, tear film function and MG morphology. Early screening and treatment of MG dysfunction may improve ocular surface quality and allow better disease management in keratoconus patients.

scholarly journals Clinical characteristics of keratoconus patients at the University of KwaZulu-Natal eye clinic

2020 ◽  
Vol 79 (1) ◽  
Author(s):  
Shishka Rupnarain ◽  
Nomvelo Madlala ◽  
Ntokozo Memela ◽  
Simpiwe Ngcobo ◽  
Nonkazimulo Shabalala ◽  
...  
Keyword(s):  
Contact Lens ◽  
Clinical Characteristics ◽  
Contact Lenses ◽  
Corneal Ectasia ◽  
Kwazulu Natal ◽  
Rigid Contact ◽  
The Mean ◽  
The University ◽  
Severe Grade ◽  
Eye Clinic

Background: Patients with keratoconus, which is a common corneal ectasia, often present to specialised clinics for management. Understanding the clinical characteristics of keratoconus patients can help improve knowledge of the presentation and management of this corneal ectasia and predict the needs of the clinic providing care for affected individuals.Aim: To describe the clinical characteristics of keratoconus patients attending the University of KwaZulu-Natal (UKZN) eye clinic.Setting: University of KwaZulu-Natal eye clinic.Methods: The study used a retrospective research design by reviewing the clinical record cards of patients attending the UKZN contact lens eye clinic over a 4-year period (January 2014 to December 2017). Data related to age, clinical characteristics and method of management of the keratoconus patients were extracted and analysed using descriptive statistics.Results: Just less than one-quarter of all patients (n = 1210) attending the UKZN contact lens eye clinic had keratoconus that was most often bilateral. The mean age at presentation was 25.2 ± 9.6 years with 74% of the sample being younger than 30 years. More than 90% (n = 419) of the sample reported refractive reasons as the primary reason for presenting to the clinic. The majority of the sample had severe keratoconus (n = 257) and rigid contact lenses were most commonly used for management of keratoconus patients.Conclusion: Keratoconus presents at an early age with a more severe grade and it is most commonly managed using rigid contact lenses. These findings should be considered for keratoconus screening, diagnosis and treatment programmes in KwaZulu-Natal.

Investigation of Lubrication Characteristics for a Soft Contact Lens

2019 ◽  
Vol 823 ◽  
pp. 105-109
Author(s):  
Hung Jung Tsai ◽  
Jeng Haur Horng ◽  
Chung Ming Tan
Keyword(s):  
Contact Lens ◽  
Contact Lenses ◽  
Hydrodynamic Lubrication ◽  
Tear Film ◽  
Hydrodynamic Pressure ◽  
Slider Bearing ◽  
Soft Contact ◽  
Soft Contact Lens ◽  
Lubrication Characteristics

It is popular to wear the contact lens nowadays. Also, the output value of the contact lens is estimated more than 4 billion NT dollar every year. Because the phenomena of the contact lenses are very complicated, the relevant mechanisms are not well understood. Thus, the security of contact lens needs to be further investigated. In the lubricated mechanism of the contact lens, there is a layer of tear between the contact lens and cornea. The contact lens’ behavior is akin to that of a slider bearing. The lens represents the slider, the eye plays the role of the stationary pad, and the tear film is the lubricant. Hence, hydrodynamics and contact mechanisms of a contact lens are quite a fascinating subject that is relevant to the science of tribology. In the paper, the lubrication mechanisms include the partial hydrodynamic lubrication (contact lens roughness), contact mechanics and Newtonian fluid mechanics have been established. The parameters of roughness, flow factor, tear film geometry, and hydrodynamic pressure distribution are discussed. The developed technology increases the safety of contact lens.

scholarly journals Pre-lens tear film evaluation scale: a tool for analyzing the tear film-lens interaction with respect to the material used

2012 ◽  
Vol 2 (1) ◽  
pp. 7
Author(s):  
Papagni Antonio ◽  
Rossella Fonte ◽  
Luca Benzoni
Keyword(s):  
Contact Lens ◽  
Contact Lenses ◽  
Tear Film ◽  
Patient Case ◽  
History Information ◽  
Eye Examination ◽  
The Relationship ◽  
Lens Surface ◽  
Insight Into

In clinical practice, to avoid or reduce the failure rate among users of contact lenses, it is necessary to obtain a detailed patient case history, information concerning symptoms, and a complete eye examination. In addition, application of an auxiliary photographic reference scale might increase the chances of improving initial success or, for existing contact lens wearers, provide insight into the extent or severity of symptoms. Patient symptoms are often directly related to contact lens failure, which in turn is related to the quality of the pre-corneal tear film as well as the <em>wettability</em> of the contact lens surface. We describe the relationship between the quality of the tear film, with particular attention to pre-contact lens tear film, variability in contact tolerance, and the material of which the contact lens is made.

scholarly journals A new surface coating designed to improve comfort for made-to-measure GP contact lenses

The Eye ◽  
2019 ◽  
Vol 126 (2019-2) ◽  
pp. 52-58
Author(s):  
Martin Conway
Keyword(s):  
Surface Properties ◽  
Contact Lens ◽  
Surface Coating ◽  
Polymer Coating ◽  
Contact Lenses ◽  
Tear Film ◽  
Deposit Formation ◽  
Dry Eyes ◽  
Optimum Range ◽  
Design And Manufacturing

Design and manufacturing of material for contact lens¬es require a balance of functionality and comfort that cannot achieved in all contact lenses. Tangible Hydra-PEG™ technology helps improve the surface properties of contact lenses of any type, including customized lenses made from any material. Tangible Hydra-PEG™ is a polymer coating; it contains 90% water, which ensures maintenance of the tear film, improve¬ment of wettability and lubricating, as well as resistance to the deposit formation, and therefore can be especially helpful to users of rigid gas-permeable contact lenses, which are worried about dry eyes or general discomfort. According to conducted studies, 69% users sur¬veyed preferred lenses coated with Tangible Hydra-PEG™ to conventional lenses due to a higher level of comfort. This technology has been approved by the FDA. Currently, the products of the Optimum range by «Con¬tamac» company are available with innovative Tangible Hydra-PEG™ coating: Optimum Classic (Dk 26), Comfort (Dk 65), Extra (Dk 100) и Extreme (Dk 125).

scholarly journals EVALUATION OF CLINICAL AND FUNCTIONAL OUTCOME OF MULTIFOCAL CORRECTION BY CONTACT LENS IN PATIENTS WITH PRESBYOPIA AND MYOPIA REFRACTION

2016 ◽  
Vol 1 (6) ◽  
pp. 103-107
Author(s):  
Рогожникова ◽  
Elena Rogozhnikova ◽  
Селиверстова ◽  
Nataliya Seliverstova ◽  
Розанова ◽  
...  
Keyword(s):  
Contact Lens ◽  
Contact Lenses ◽  
Tear Film ◽  
Functional Results ◽  
Corneal Epithelial ◽  
Interaction Field ◽  
Standard Procedures ◽  
Quality Of Vision ◽  
Selection Of

The aim of the study was to evaluate the effectiveness of multifocal contact lens correction in patients with presbyopia and myopic refractive error. The study involved 45patients with myopia ranging in age from 43 to 56years in conditions of habitual monofocal contact lens correction, a month after the selection and wearing multifocal contact lenses. Contact correction was carried out according to standard procedures taking into account the accuracy of contact lens fitting, with carrying out functional tests for the “dry eye” syndrome and evaluation of corneal epithelial thickness (Optovue, USA). The as-sessment of the following parameters of visual perception was made: far, near and middle distance (monocular and binocular) visual acuity, the spatial contrast sensitivity, stereovision (I &amp; II Lang test), the area of binocular interaction field (binarymeter), the quality of vision (VF-14 test ). The use of multifocal contact lenses for the correction of presbyopia with the initial myopic refraction ensures high functional results at different distances. Patients with a myopic refraction, previously used contact lenses, easy pass to multifocal correction option. The greatest satisfaction by achieved vision noted in those patients who had achieved refraction (–)0.5diopters. In the selection of contact lenses in older patients the thickness of the corneal epithelium and tear film validity must be taken into account.

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