Types Of Contact Lenses Research Articles

A Study on Contact Lens Wear Status of After Corneal Refractive Surgery Subjects

Purpose: After corneal refractive surgery, status of contact lens wearers and the base curve and the diameter of soft contact lenses were identified through investigation. Methods: A survey on contact lens wearing situation with 261 individuals experienced corneal refractive surgery was analyzed. cornea's curvature of after Corneal refractive correction surgery Subjects was measured. The base curves and lens diameters of the 328 types of contact lenses of 37 companies in Korea were analyzed. Results: After corneal refractive surgery it was shown that 16.5% of those were wearing or experience contact lens, and in the purpose of wearing a cosmetic reason was the highest accounting for 81.4%. 86% of people chose an optical shop to purchase contact lenses, and 88.4% of them were wearing cosmetic contact lenses. 58.1% of those who experience a refractive surgery did not inform their history when purchasing contact lenses, and also 65.1% of them bought them without any examination. While wearing contact lens, they answered about uncomfortable details, such as dryness(39.5%), lens movements(18.6%), redness(14%), tears(4.7%) and pain(2.3%). People who want to continuously wear contact lens appeared 25.7%. The average of the average of the flat corneal curvature after surgery was 8.41±0.31mm, steep corneal curvature was found altered comfortable flat with 8.21±0.34mm. On the Korean domestic market, 8.6mm(70.7%) in the base curve of contact lenses, and 14.0mm(41.2%) and 14.2mm(35.1%) in diameter were most distributed, representing that the sort of contact lens for fitting was limited. Conclusions: Despite corneal refractive surgery for a vision correction, people were wearing contact lens just for cosmetic purposes. It was appeared that the types of lens were limitative, and detail examination or the information on a side effect was insufficient. Therefore, it would be necessary to improve for that.

Facteurs de risque de kératites infectieuses chez les porteurs de lentilles de contact, une étude cas-témoins

Currently, the most feared complication by ophthalmologists of contact lens (CL) wear is microbial keratitis (MK), even though its incidence remains low. It is also a significant financial burden for society. This study aimed to identify the risk factors for CL-related MK especially with regard to hygiene and pattern of use, in a large, prospective, multicenter, case-control study. A multicenter retrospective case-control study was designed. The CL-related MK subpopulation (case) was compared with healthy CL wearers (control) using a 52-item anonymous questionnaire designed to determine subject demographics, lens wear history, lens type and disinfection solution, fitting, patient education, hygiene and maintenance of contact lenses, and patient history. Univariate logistic regression analysis was performed to compare both groups. The study included 497cases and 364controls. The risk factors associated with the greatest increased odds of CL-related MK were as follows: extended wear (OR=2.96 [1.65-5.33], P<0.001), occasional overnight lens use (OR=6.37 [4,55-8.90], P<0.001), fitting by an optician (OR=1.97 [1.38-2.83], P<0.001), absence of ophthalmologic exam (OR=6.56 [2-22], P<0.01) or no training in handling the contact lens (OR=4.47 [2.27-8.77], P<0.01), use of optician's disinfection solution (OR=5.55 [3.12-9.85], P<0.001), mixing solutions ("topping off") (OR=4.68 [2.73-8.04], P<0.001), no case replacement (OR=3.95 [2.28-6.82] P<0.01), no compliance with hygiene rules and smoking (OR=2.29 [1.67-3.14], P<0.01). The protective factors associated with the greatest reduction in OR were female gender (OR=0.49 [0.36-0.66], P<0.01), hypermetropia (OR=0.28 [0.16-0.48], P=0.01), rigid contact lens wear, fitting by an ophthalmologist, written and verbal instruction, and daily case maintenance. The knowledge of these risks factors incentivizes action at all levels to reduce the incidence of MK, from the prescriber to the patient, including the type of CL, case and contact lens solution.

Effects of contact lens wearing on keratoconus: a confocal microscopy observation.

To evaluate the corneal cell morphology of new keratoconus patients wearing two different types of rigid gas-permeable (RGP) contact lenses for 1y. Thirty nine eyes of 39 new keratoconus patients were selected and randomly fitted with two types of RGP contact lenses. Group 1 had 21 eyes with regular rigid gas-permeable (RRGP) contact lens and rest 18 eyes were in group 2 with specially designed rigid gas-permeable (SRGP) contact lens. Corneal cell morphology was evaluated using a slit scanning confocal microscope at no-lens wear and after 1y of contact lens wearing. After 1y of contact lens wearing in group 1, the mean anterior and posterior stromal keratocyte density were significantly less (P=0.006 and P=0.001, respectively) compared to no-lens wear. The mean cell area of anterior and posterior stromal keratocyte were also significantly different (P=0.005 and P=0.001) from no-lens wear. The anterior and posterior stromal haze increased by 18.74% and 23.81%, respectively after 1y of contact lens wearing. Whereas in group 2, statistically significant changes were observed only in cell density & area of anterior stroma (P=0.001 and P=0.001, respectively) after 1y. While, level of anterior and posterior stromal haze increased by 16.67% and 11.11% after 1y of contact lens wearing. Polymegathism and pleomorphism also increased after 1y of contact lens wearing in both the contact lens groups. Confocal microscopy observation shows the significant alterations in corneal cell morphology of keratoconic corneas wearing contact lenses especially in group 1. The type of contact lens must be carefully selected to minimize changes in corneal cell morphology.

Conjunctival Microbiome Changes Associated With Soft Contact Lens and Orthokeratology Lens Wearing.

Usage of different types of contact lenses is associated with increased risk of sight-threatening complications. Changes in the ocular microbiome caused by contact lens wear are suggested to affect infection development in those individuals. To address this question, this study compares conjunctival microbial communities in contact lens wearers with those in noncontact lens wearers. Paired-end sequencing of the V3 region of the 16S rRNA gene was used to characterize the bacterial communities on the conjunctival surfaces of contact lens wearers and nonwearers. No differences in microbial diversity were detected between contact lens wearers and nonwearers. Nevertheless, some slight microbe variability was evident between these two different groups. Bacillus, Tatumella and Lactobacillus abundance was less in orthokeratology lens (OKL) wearers than in nonwearers. In soft contact lenses (SCL) wearers, Delftia abundance decreased whereas Elizabethkingia levels increased. The difference in the SCL and nonwearer group was smaller than that in the OKL group. Variations in the conjunctival taxonomic composition between SCL wearers were larger than those in other groups. Sex differences in the conjunctival microbiota makeup were only evident among nonwearers. Even though there were slight percentage changes between contact lens wearers and nonwearers in some microbes, there were no differences in their diversity. On the other hand, contact lens usage might cause relative abundance of some taxa to change. Our results will help assess whether or not conjunctival microbiome changes caused by contact lens wear affect infection risk.

소프트 콘택트렌즈 착용자의 피팅 상태에 따른 각막 이심률과 곡률반경과의 상관관계

Purpose. Because of a recent increase in use of soft contact lens at younger ages, in the present study, the correlation between corneal eccentricity and radius of curvature and fitting types of contact lens was investigated. Methods. The study evaluated the fitting status of targets through lens centration, push-up test, dynamic lag test and static lag test of lenses usually worn by 49 men and women (98eyes) in their 20s to 30s who put on soft contact lenses. After evaluation, the subjects were classified into 3 categories by fitting status(steep, aligment and flat). The radius of corneal curvature in the naked eyes was measured by using keratometer. Moreover the corneal eccentricity in the nasal side, temporal side, superior side and inferior side was measured by using the device capable of measuring the corneal eccentricity. Results. The radius of corneal curvature and corneal eccentricity of soft lenses worn by subjects were higher in the order of steep fitting and flat fitting, and the higher average corneal curvature radius and corneal eccentricity is intend to be more steep fitting(p=0.051, p=0.052). The corneal eccentricity showed a tendency to nasal fitting type at the higher eccentricity and temporal fitting type at the smaller eccentricity, statistically significant difference was observed(p<0.05). The study showed there were low correlation that nasal and temporal side at steep fitting, superior side at normal fitting and 4side(nasal, temporal, superior, inferior) at flat fitting, therefore when the corneal eccentricity changed the radius of corneal curvature also changed. The corneal eccentricity and the radius of corneal curvature showed statistically significant difference at 4side and each fitting types(p<0.05). Conclusions. The results of this study, the fitting status, of wearer are based on radius of corneal curvature and corneal eccentricity, and if lens fitting would be done considering that, it seems to be useful in a soft contact lens prescription.

Ocular response to environmental variations in contact lens wearers.

To assess the influence of different indoor environments simulated in an environmental chamber on soft contact lens (CL) wearers. Fifty-four CL wearers were grouped based on their symptoms while wearing their CLs. Subjects were fitted with two different CL types, conventional hydrogel (Omafilcon A) and silicone hydrogel (comfilcon A), and exposed to two controlled indoor environmental conditions, standard [50% relative humidity (RH), 23°C, 930mb of atmospheric pressure] and adverse (in-flight air cabin environment: 5% RH, localised air flow, 23°C, 750mb atmospheric pressure), for 90min in an environmental chamber, making a total of four visits. Symptoms, tear osmolarity, pre-lens tear breakup time (PLBUT), phenol red thread test, visual acuity, bulbar and limbal hyperaemia, corneal and limbal staining, and CL dehydration were assessed using repeated measures analysis of variance. A linear mixed model was used to analyse the effect of environment, CL type, discomfort-based grouping, and time on blink rate. Environment was found to significantly (p≤0.018) affect limbal and bulbar hyperaemia, PLBUT, tear osmolarity, and CL dehydration. Likewise, CL type significantly (p≤0.04) affected nasal and total corneal staining, limbal conjunctival staining, CL dehydration, comfort, and blurred vision. The environment, CL type, and time had significant effects (p≤0.0001) on the blink rate. Ocular surface integrity and blink rate in CL wearers depend on the environment CL users are exposed to, as well as on the soft CL type that they are wearing. Tight control of environmental conditions can contribute to a better understanding of CL-related discomfort.

Violet Light Exposure Can Be a Preventive Strategy Against Myopia Progression

Prevalence of myopia is increasing worldwide. Outdoor activity is one of the most important environmental factors for myopia control. Here we show that violet light (VL, 360–400nm wavelength) suppresses myopia progression. First, we confirmed that VL suppressed the axial length (AL) elongation in the chick myopia model. Expression microarray analyses revealed that myopia suppressive gene EGR1 was upregulated by VL exposure. VL exposure induced significantly higher upregulation of EGR1 in chick chorioretinal tissues than blue light under the same conditions. Next, we conducted clinical research retrospectively to compare the AL elongation among myopic children who wore eyeglasses (VL blocked) and two types of contact lenses (partially VL blocked and VL transmitting). The data showed the VL transmitting contact lenses suppressed myopia progression most. These results suggest that VL is one of the important outdoor environmental factors for myopia control. Since VL is apt to be excluded from our modern society due to the excessive UV protection, VL exposure can be a preventive strategy against myopia progression.

Contact lenses wearing. How much do patients know and how to improve it.

Aim: To assess the level of knowledge and experience of contact lens users who have attended the eye casualty seeking advice and treatment for contact lens related problem. The articlewill also providea concise review of the literature regarding contact lens history, types, uses and complications and explore the pathophysiology of the contact lens related conditions. The article will discuss the management and preventive measures for those conditions that may lead to blindness.Methods: Prospective review of patients who have attended a regional eye casualty over a period of January to March 2015.Patients were recruited following the triage details provided. The inclusion criteria was all contact lens users aged16years and above and have been using contact lens for a minimum of 6 months. Survey questionnaire were given to patients who filled them prior to their consultation with the ophthalmologist. The audit was registered with the clinical effectiveness department of the author’s Trust.Extensive review of the literature in regards to contact lens also has been carried out.Results: There were a total of 63 patients under review during the study period consisting of 29 males and 34 females. Ages ranged from 16–80 years. The most common type of lenses used is the soft monthly contact lenses which were found in 55.5% of the target group.The survey has shown the optician as the main provider for the lens in 95% , with the remaining of patients order them online.More than 60% of the target group have shown bad behaviour in sleeping, swimming and showering while having the contact lens in. The majority have indicated that they were given instructions on insertion and removing of the contact lens. However 33.4% have not had information when to seek medical advice. The main source of information given to the users was the optician in 58.8% followed by other resource such as internet, leaflets, and friends in 39.6%. Neither the GP nor the nurse has shown to provide any advice and this could be explained as the optician is the main contact and provider for the contact lens and the only contact with the GP or the Practice nurse would be when there is an issue with the ocular health.The daily duration of wearing contact lens ranged from 4-18 hrs. The figures given has shown an over usage of such lens by some of those users. Furthermore, 55.5% of the users have indicated the using of lubrication eye drops with their contact lens.1in 2 have experienced contact lens related issues prior to their attendance that range from dry eyes to sight threatening corneal ulcersFinally 57% of the target group have been diagnosed with contact lens related infective keratitis and have been treated with intensive topical antibiotics, while the rest have other contact lens related issue that varies from tear film disturbance to allergic conjunctivitis and superficial punctate keratitis.The survey strongly emphasises the need to re-educate contact lens users about the standard guidelines and activities required to follow while wearing contact lens.Conclusion: Providing advice and education to the contact lenses users is imperative and following the standardsguidelines of contact lens, care is essential for usersin order to avoid any sight threatening condition. There is a need to re-educate patients regarding their contact lens care and the preventive measure of contact lens related complications.

Allergic manifestations of contact lens wearing.

Contact lens-induced papillary conjunctivitis (CLPC) is a common ocular allergic disease in contact lens wearers. In its more severe form, it can cause giant papillary conjunctivitis, resulting in contact lens intolerance and the need to discontinue the use of contact lenses. This review presents the pathogenesis, clinical manifestations and management guidelines of this common disorder. Different types of contact lenses are associated with differences in the severity of CLPC. Refitting patients with silicone hydrogel contact lenses or with daily disposable contact lenses may improve the signs and symptoms of CLPC. The recent introduction of the topical immunomodulatory agent tacrolimus in other severe allergic eye diseases may apply in suppressing the allergic inflammation in CLPC as well. CLPC is a common ocular disorder in contact lens wearers, with a significant impact on the quality of vision. It should be promptly recognized by healthcare practitioners and managed by modifications of the types and wearing schedules of contact lenses, as well as novel treatment options with topical immunomodulators.

Effect of Environmental Conditions on the Concentration of Tear Inflammatory Mediators During Contact Lens Wear.

To analyze the influence of environmental conditions on the concentrations of tear inflammatory mediators during contact lens (CL) wear. Fifty-four CL wearers completed 4 visits combining the bilateral use of omafilcon A or comfilcon A CL and a 90-minute exposure to 2 environmental conditions: standard [50% relative humidity (RH), 23°C, 930 mb] or adverse (5% RH, localized air flow, 23°C, 750 mb). Four microliters of tears was collected by capillarity from each subject. Changes in concentration of epidermal growth factor (EGF); interleukin (IL)-1 receptor antagonist, IL-1β, IL-2, IL-4, IL-6, and IL-8; tumor necrosis factor (TNF) α; monocyte chemoattractant protein-1; and matrix metalloproteinase (MMP)-9 were analyzed. The effects of the environment, CL type, and symptoms were evaluated using a 3-way mixed analysis of variance with repeated measures. Under the standard condition, EGF significantly increased [0.36; 95% confidence interval (CI), 0.08 to 0.64], and IL-1β (-0.48; 95% CI, -0.84 to -0.12) and IL-2 (-0.48; 95% CI, -0.87 to -0.09) significantly decreased. Under the adverse condition, IL-6 significantly increased (0.35; 95% CI, 0.09 to 0.62). Comparing conditions, EGF change was significantly lower (P = 0.02) and IL-1β, IL-2, IL-6, and TNF-α changes were significantly higher (P ≤ 0.04) under the adverse condition. Additionally, IL-1β significantly decreased with comfilcon A (-0.51; 95% CI, -0.88 to -0.15), being significantly lower (P = 0.01) than the change with omafilcon A (0.06; 95% CI, -0.23 to 0.35). The secretion of several tear inflammatory mediators during CL wear differs depending on the environmental conditions and the CL type used. These outcomes might help to understand the effect of the environment and CL materials on the ocular surface of CL wearers.

Ocular Drug Delivery through pHEMA-Hydrogel Contact Lenses Co-Loaded with Lipophilic Vitamins

Ocular drug delivery through hydrogel contact lenses has great potential for the treatment of ocular diseases. Previous studies showed that the loading of lipophilic vitamin E to silicone-hydrogel contact lenses was beneficial in ocular drug delivery. We hypothesized that vitamin E loading to another type of popular hydrogel contact lenses, pHEMA-hydrogel contact lenses, improves ocular drug delivery by increasing the drug loading or the duration of drug release. Loading of vitamin E to pHEMA-hydrogel contact lenses significantly increased the loading of a hydrophilic drug surrogate (Alexa Fluor 488 dye) and two hydrophilic glaucoma drugs (timolol and brimonidine) to the lenses by 37.5%, 19.1%, and 18.7%, respectively. However, the release duration time was not significantly altered. Next, we hypothesized that the lipophilic nature of vitamin E attributes to the enhanced drug loading. Therefore, we investigated the effects of co-loading of another lipophilic vitamin, vitamin A, on drug surrogate delivery. We found out that vitamin A loading also increased the loading of the drug surrogate to pHEMA-hydrogel contact lenses by 30.3%. Similar to vitamin E loading, vitamin A loading did not significantly alter the release duration time of the drug or drug surrogate.

Effect of bandage contact lens wear and postoperative medical therapies on corneal healing rate after diamond burr debridement in dogs.

To determine the effect of bandage contact lens wear and type of post-operative medical treatment on corneal healing rates in dogs after diamond burr debridement. 237 client-owned dogs. Canine patients having undergone diamond burr debridement (DBD) for treatment of spontaneous chronic corneal epithelial defects (SCCEDs) were included. Patients were put into 1 of 12 different groups based on type of postoperative medical regimen and whether a bandage contact lens (BCL) was utilized. Each dog was examined on a routine basis until the cornea was fluorescein negative. Data points collected included age, sex, breed, diabetic status, eye affected, Schirmer tear test 1, rebound tonometry, type and frequency of topical antibiotic, use of topical sodium chloride, use and retention of BCL, and days until healed. A total of 237 dogs, each contributing one eye to the study, underwent DBD for SCCEDs. All eyes treated had estimated median±standard error (SE) days to heal of 9.37±0.42days. When sodium chloride and BCL were utilized, ofloxacin had a significantly shorter median healing time when compared to oxytetracycline (adjusted P=0.0158) and tobramycin (adjusted P=0.0261). BCL use significantly improved healing times (P=0.0002). Overall BCL retention rate was 62.02% (80 of 129). PureVision lenses were retained more often compared to Acrivet lenses (P<0.0001). Overall, BCL retention significantly improved healing rates (P=<0.0001). Postdebridement antibiotic type or use of sodium chloride ointment had minor effects on healing rates. Bandage contact lens use and retention significantly improves healing times.

Effects of Pigment Location in Tinted Contact Lenses on the Ocular Surface.

To evaluate the effects of the location of pigments in decorative tinted soft contact lenses on the ocular surface. Thirty test subjects were enrolled in this study. All subjects wore the following types of contact lenses, classified according to the location of the pigment layer, in one eye in three different testing sessions: conventional clear lenses, tinted lenses with a pigment layer embedded in the lens matrix, and tinted lenses with an exposed pigment layer on the surface. Tear samples were collected, the ocular surface status was evaluated, and subjective symptoms were surveyed after lens wear for 8 hours. The tinted lenses with surface pigments resulted in a greater increase in epidermal growth factor and interleukin-8 levels compared with the clear lenses and tinted lenses with embedded pigments (p < 0.050). Ocular surface parameters and subjective symptom scores were significantly different among three lens types (p < 0.050), with the clear lenses showing superior results compared with the two tinted lenses (p < 0.050). The tinted lenses with exposed pigments resulted in a greater degree of conjunctival redness and ocular surface staining and poorer symptom scores compared with the tinted lens with embedded pigments (p < 0.050). Our results suggest that the presence of surface pigments in tinted contact lenses increases ocular inflammation and results in a poorer ocular surface status and greater discomfort compared with clear lenses and tinted lenses with an embedded pigment layer.

Platelet lysate and chondroitin sulfate loaded contact lenses to heal corneal lesions

Hemoderivative tear substitutes contain various ephiteliotrophic factors, such as growth factors (GF), involved in ocular surface homeostasis without immunogenic properties.The aim of the present work was the loading of platelet lysate into contact lenses to improve the precorneal permanence of platelet lysate growth factors on the ocular surface to enhance the treatment of corneal lesions.To this purpose, chondroitin sulfate, a sulfated glycosaminoglycan, which is normally present in the extracellular matrix, was associated with platelet lysate. In fact, chondroitin sulfate is capable of electrostatic interaction with positively charged growth factors, in particular, with bFGF, IGF, VEGF, PDGF and TGF-β, resulting in their stabilization and reduced degradation in solution. In the present work, various types of commercially available contact lenses have been loaded with chondroitin sulfate or chondroitin sulfate in association with platelet lysate to achieve a release of growth factors directly onto the corneal surface lesions. One type of contact lenses (PureVision®) showed in vitro good proliferation properties towards corneal cells and were able to enhance cut closure in cornea constructs.

Cavitas Sensors: Contact Lens Type Sensors &amp; Mouthguard Sensors

Abstract“Cavitas sensors” attached to body cavities such as the contact lens and mouthguard (“no implantable”, “no wearable”) are attracted attention as self‐detachable devices for daily medicine. Many types of contact lens (CL) sensors using electrical and optical methods have been developed for monitoring not only chemicals (glucose, lactate) and electrical conductivity in tear fluid, but also transcutaneous gases at eyelid mucosa. A CL intraocular pressure telemetric sensor has been also commercialized and applied to patients for monitoring the intraocular pressure. Some mouthguard sensors have been investigated for a real‐time measurement of salivary chemicals. A graphene based sensor on tooth enamel was reported to be capable of salivary bacterium detection. Here we review the challenges regarding the integration of biosensors into monitoring for biological information of body cavities. The self‐detachable cavitas sensors are expected to improve the quality of life in the near future.

Use of Scleral Lenses and Miniscleral Lenses After Penetrating Keratoplasty.

To examine the clinical outcomes of scleral lenses for visual rehabilitation after penetrating keratoplasty (PK). A retrospective review was conducted for 34 patients (48 eyes) who had a history of prior PK and were fit with scleral lenses between October 2009 and December 2013 at the UC Davis Eye Center. The most common initial indication for PK was keratoconus in 27 eyes (56%). Thirty-three eyes (69%) had previously been fit with other types of contact lenses, with small-diameter rigid gas-permeable lenses being the most common. The improvement in best-corrected visual acuity with a scleral lens compared with prior spectacle refraction or other contact lens was a mean of two best-corrected visual acuity lines. Forty-four eyes (91.7%) achieved functional vision with best scleral lens-corrected visual acuities of 20/40 or better. Patients who continued wearing scleral lenses were significantly more likely to report "good" subjective vision compared with patients who abandoned scleral lens wear (P=0.009), although change in objective best-corrected visual acuity did not differ significantly. There were no cases of infectious keratitis. Six eyes (12.5%) developed graft rejection; 3 were able to resume scleral lens wear. Nineteen eyes (39.5%) discontinued scleral lens wear for various reasons, the most common reason for discontinuation of lens wear was difficulty with scleral lens insertion or removal (8 eyes, 42.1%). Scleral lenses are effective and safe in patients who have had PK. There was a mean gain in visual acuity, with the majority of patients achieving 20/40 vision or better. The patient's subjective perception of vision was a significant factor in determining whether scleral lens wear was continued or abandoned.

Objective and subjective evaluation of the performance of medical contact lenses fitted using a contact lens selection algorithm.

To evaluate the performance of medical contact lenses (CLs) for a wide range of clinical indications. Prospective cross-sectional study. A total of 281 eyes were evaluated in 281 consecutive patients (≥18 years of age; CL use ≥3 months) who visited the contact lens service in a tertiary academic clinic for a scheduled follow-up visit. The main outcome measured were clinical indications for CL wear; CL type; change in corrected distance visual acuity (CDVA) with CL use; CL wearing duration; CL wearing time; subjective performance measured using a visual analog scale (VAS) questionnaire (score range: 0-100); and effectiveness of the lens-selection algorithm. Wearing CLs significantly improved CDVA compared to wearing spectacles (median change: -0.15 logMAR, range: 1.00 to -2.10; P<.001). Daily-wear CLs were worn by 77% of patients for a median of 15h/day (range: 5-18h/day), median 7 days/week (range: 1-7 days/week). High subjective scores were measured, with similar results obtained between the scleral lens and soft lens groups. The medical CL fitting was found to be generally effective (the overall satisfaction rating was ≥70 for 81% of patients). Fitting CLs based on the lens-selection algorithm yielded positive clinical results, including improved visual acuity, satisfactory wearing time, and high overall subjective performance. Moreover, subjective performance was similar between users of scleral lenses and users of soft lenses. These results underscore the importance of prescribing scleral lenses and the need for tertiary eye clinics to offer patients a variety of CL types.

Effect of contact lens use on Computer Vision Syndrome.

To analyse the relationship between Computer Vision Syndrome (CVS) in computer workers and contact lens use, according to lens materials. Cross-sectional study. The study included 426 civil-service office workers, of whom 22% were contact lens wearers. Workers completed the Computer Vision Syndrome Questionnaire (CVS-Q) and provided information on their contact lenses and exposure to video display terminals (VDT) at work. CVS was defined as a CVS-Q score of 6 or more. The covariates were age and sex. Logistic regression was used to calculate the association (crude and adjusted for age and sex) between CVS and individual and work-related factors, and between CVS and contact lens type. Contact lens wearers are more likely to suffer CVS than non-lens wearers, with a prevalence of 65% vs 50%. Workers who wear contact lenses and are exposed to the computer for more than 6 h day(-1) are more likely to suffer CVS than non-lens wearers working at the computer for the same amount of time (aOR = 4.85; 95% CI, 1.25-18.80; p = 0.02). Regular contact lens use increases CVS after 6 h of computer work.

Descriptive analysis of the type and design of contact lenses fitted according to keratoconus severity and morphology

Keratoconus is characterized by bilateral asymmetrical corneal ectasia that leads to inferior stromal thinning and corneal protrusion. There is currently a lack of consensus regarding the most efficacious method for fitting contact lenses in patients with keratoconus, given the various topographical patterns and evolution grades observed in affected populations. The purpose of the present study was to evaluate the association between keratoconus evolution grade and topography pattern and the type and design of fitted contact lens. We performed a retrospective analysis of contact lenses fitted in a total of 185 patients with keratoconus (325 eyes). Keratoconus was classified as either grade I, II, III, or IV based on keratometry and cone morphology (nipple, oval, globus, or indeterminate) results. A total of 325 eyes were evaluated in the present study. Of the 62 eyes classified as grade I, 66.1% were fitted with monocurve contact lenses. Of the 162 eyes classified as grade I and II, 51%, 30%, and 19% were fitted with adapted monocurve rigid gas-permeable contact lenses (RGPCL), bicurve lenses, and others lens types, respectively. Bicurve lenses were fitted in 52.1% and 62.2% of eyes classified as grade III and IV, respectively. Of the eyes classified as grade III and IV, monocurve and bicurve RGPCL were fitted in 26% and 55%, respectively. In eyes with oval keratoconus, 45%, 35%, and 20% were fitted with monocurve lenses, bicurve lenses, and other lens types, respectively. In eyes with round cones (nipple morphology), 55%, 30%, and 15% were fitted with bicurve lenses, monocurve lenses, and other lens types, respectively. Monocurve RGPCL were most frequently fitted in patients with mild to moderate keratoconus and oval cones morphology, while bicurve lenses were more frequently fitted in patients with severe and advanced keratoconus. This was probably because bicurve lenses are more appropriate for round cones due to increased corneal asphericity.

Investigation of the Degree of Disorder of the Structure of Polymer Soft Contact Lenses Using Positron Annihilation Lifetime Spectroscopy PALS.

Hydrogel and silicone-hydrogel polymeric materials are widely used in ophthalmology for the manufacture of contact lenses. An important aspect is the investigation of the structure of these materials. This study has been conducted in order to compare the degree of disorder and presence of free volumes in the internal structure of the polymeric soft contact lenses Omafilcon A (hydrogel) and Comfilcon A (silicone-hydrogel). Differences in the occurrence of trapping centers for positrons and free volumes between the types of investigated contact lenses have been demonstrated. Two types of polymeric contact lenses were used as materials: Omafilcon A (hydrogel) and Comfilcon A (silicone-hydrogel). The study was performed using positron annihilation lifetime spectroscopy (PALS). When the results of the measurements has been obtained, a graphical curve has created to describe the relationship of the number of annihilation acts in time. Significant changes were observed between the contact lenses investigated in positron trapping in macropores (based on a two-state model) and the presence of free volumes (based on the Tao-Eldrup model). The use of the positron annihilation two-state model made it possible to demonstrate that a higher positron trapping rate in macropores occurs in the silicone-hydrogel contact lens. Additionally, calculations using the Tao-Eldrup model show the existence of free volumes in both types of materials. The size and fraction of free volumes is much larger in the silicone-hydrogel contact lens.