Contact Lenses In Order Research Articles

Comparison of visual performance between extended depth of focus contact lens and single-vision contact lens in eyes with monofocal intraocular lens.

To assess the visual performance of extended depth of focus (EDF) contact lenses (CL) in eyes that had undergone monofocal intraocular lens (IOL) implantation, and compare that between EDF and single-vision (SV) contact lenses. Prospective, randomized, crossover study METHODS: Seventeen patients implanted with monofocal IOLs were enrolled. The study was conducted using 1dayPure EDOF as a test CL and 1dayPure moisture (both SEED Co., Ltd.) as a control CL. Binocular visual acuity from far to near distances, photopic and mesopic contrast sensitivity (with and without glare), and stereopsis were evaluated after wearing the two kinds of CLs in random order. The obtained results were compared between the EDF and SV CLs. Binocular visual acuity at 0.3, 0.4, 0.7, 1, and 5m was 0.24 ± 0.12, 0.07 ± 0.09, - 0.02 ± 0.08, - 0.02 ± 0.08, and - 0.06 ± 0.07 logMAR during the EDF CL wear, respectively, and 0.39 ± 0.17, 0.26 ± 0.15, 0.04 ± 0.12, - 0.02 ± 0.08, and - 0.09 ± 0.09 during the SV CL wear, respectively. The EDF CL showed better results than the SV CL at 0.3, 0.4, and 0.7m (p < 0.05). There were no significant differences in contrast sensitivity between the EDF and SV CLs at 1.5 cycles per degree under all conditions; however, the sensitivity of the EDF CL was generally worse than that of the SV CL from the middle to high spatial frequencies. Stereopsis at 40cm was significantly better in the EDF CL wear than in the SV CL wear (p < 0.05). The EDF CL substantially improved visual acuity at near to intermediate distances in IOL-implanted eyes. However, far visual acuity decreased under low-contrast conditions, and contrast sensitivity slightly declined at the middle to high spatial frequencies.

Oxygen transmissibility of various soft daily disposable toric contact lenses using high resolution thickness profiling

Purpose: To measure all-lens thickness for a range of daily disposable soft toric contact lenses in order to understand the impact of lens design and material on oxygen transmissibility.

Comparison of Dk/t values of daily disposable soft toric contact lenses using high resolution thickness profiling

Purpose: To measure all-lens thickness for a range of daily disposable soft toric contact lenses in order to calculate average Dk/t from the central 6 mm zone and evaluate those values against the Holden-Mertz criterion for daily wear.

Scleral contact lenses for the management of complicated ptosis

ABSTRACTPurpose: To present the management of three patients suffering from ptosis of various etiologies, with scleral contact lenses.Material and methods: Three patients (five eyes) with ptosis resulting from levator dehiscence due to long-term rigid gas permeable contact lens wear for keratoconus, phthisis bulbi, and myopathy due to Kearns–Sayre syndrome were identified during a 2-year period. They were fitted with scleral contact lenses in order to provide cosmesis by lifting the upper eyelid with the bulk of the lens, and simultaneously provide vision correction where applicable.Results: The scleral contact lenses provided comfortable wear, significantly improved cosmesis as both palpebral aperture and marginal reflex distance were increased, and visual acuity was also subjectively and objectively improved. Two of the patients opted for the scleral contact lenses, whereas the parents of the third patient, a 10-year-old girl with Kearns–Sayre syndrome, chose to undergo ptosis surgery due to handling issues of the scleral contact lenses.Conclusion: Scleral contact lenses can be a useful addition to the treatment option for patients with complicated ptosis.

Fractal Features and Surface Micromorphology of Unworn Surfaces of Rigid Gas Permeable Contact Lenses

ABSTRACTPurpose: The aim of this exploratory study was to investigate the micromorphology of surfaces of rigid gas permeable (RGP) contact lenses (CLs) using atomic force microscopy (AFM) followed by fractal analysis.Materials and methods: In order to characterize in a quantitative manner the micromorphology of surfaces of new and unworn RGP CLs made of twelve different materials, AFM was taken and then analyzed using fractal methods. Surface topography was sampled in an intermittent-contact mode in air, on square areas of 5 × 5 µm2 (MultiMode with Nanoscope V (Bruker). Spatial characteristics of 3-D surface texture were obtained using parameters defined in ISO 25178-2: 2012 norm.Results: The surface texture turned out to have complex 3-D nanoscale geometry. For quantitative characterization of the properties of surface geometry at nanometer level of CL on the global scale, a series of fractal parameters was used.Conclusions: Statistical and fractal parameters of 3-D surfaces can be used by manufacturers to assess the micromorphology of CLs in order to improve their 3-D surface texture characteristics. These parameters can also be used in an elastic–plastic finite element model with contact elements to simulate the friction, wear and micro-elastohydrodynamic lubrication at a nanometer scale between the CL with the corneal surface.

How to improve Visual Acuity after Intrastromal Corneal Ring Segments? Implantation for Keratoconus and Post-LASIK Ectasia

ABSTRACT Keratoconus (KC) is an ecstatic corneal disease that causes irregular astigmatism which cannot be corrected by glasses, the irregular astigmatism causes loss of visual acuity (VA) both the uncorrected and the corrected VA, in addition to deterioration in the quality of vision. Contact lenses (CLs) improve the VA but cannot be tolerated in many cases due to several causes, such as loss of motivation, atopic and allergic conjunctivitis that are more frequently associated with KC and dry eyes. Intrastromal corneal ring segments implanted in keratoconic eyes improve uncorrected visual acuity (UCVA), best spectacle corrected visual acuity (BSCVA), reduce myopia, astigmatism, high order aberrations (HOA) and regularizes the cornea (less irregular astigmatism), similar results are achieved in the treatment of post-LASIK and post PRK ectasia. These results were confirmed in long-term follow-up. The more advanced the KC the more is the effect of the ICRS but the less the functional VA achieved and vice versa. Thicker rings are more effective, and the smaller the optical zone the more is the effect of the ICRS. The aim of ICRS implantation in KC is not to be free of glasses or CL but to enable the patient of seeing with glasses or to tolerate CL in order to prevent or delay the need for penetrating keratoplasty (PKP) or deep anterior lamellar keratoplasty (DALK). In many cases, we can achieve a functional and satisfactory UCVA with no need for glasses and this is the case in nonadvanced KC but not in the advanced cases. In some cases, the results achieved need additional means to improve VA in order to get satisfactory VA. There are nonsurgical and surgical means to improve VA after ICRS, these means will be reviewed in this article. How to cite this article Barbara A, Barbara R. How to improve Visual Acuity after Intrastromal Corneal Ring Segments? Implantation for Keratoconus and Post-LASIK Ectasia. Int J Kerat Ect Cor Dis 2014;3(2):69-75.

Visual performance of two simultaneous vision multifocal contact lenses

To evaluate and compare the visual performance of two simultaneous vision multifocal contact lenses (CLs). In this cross-over study design 20 presbyopic subjects were fitted with two different simultaneous vision multifocal CLs (the PureVision Multifocal Low Add and Acuvue Oasys for Presbyopia) in random order. After 1 month, binocular distance visual acuity (BDVA) under photopic (85 cd/m(2)) and mesopic (3 cd/m(2)) conditions, binocular near visual acuity (BNVA), binocular distance contrast sensitivity function (CSF) under photopic and mesopic conditions, binocular near CSF and defocus curve were measured. Subjects were then refitted with the alternative correction and the procedure was repeated. Mean BDVA under photopic conditions was similar for the Acuvue Oasys for Presbyopia and PureVision Multifocal Low Add: 0.01 ± 0.08 and 0.00 ± 0.08 logMAR, respectively (P = 0.45). Under mesopic conditions the values of BDVA were 0.20 ± 0.58 and 0.11 ± 0.09 logMAR, respectively (P = 0.005). Mean BNVA was 0.20 ± 0.05 and 0.15 ± 0.08 logMAR for the Acuvue Oasys and PureVision Low Add, respectively (P = 0.06). Binocular distance CSF testing revealed no statistically significant differences between lenses under photopic, mesopic or near conditions. Both lenses provided a comparable intermediate visual acuity. Both simultaneous vision multifocal CLs provided adequate distance visual quality under photopic and mesopic conditions, and better visual acuity was provided under mesopic conditions for the Purevision lens. Both lenses provided adequate visual performance at intermediate distance, but the near visual acuity appears to be insufficient for early presbyopes who require a moderately demanding near visual quality.

Clinical importance of spherical and chromatic aberration on the accommodative response in contact lens wear

The aim of this study was to evaluate the accommodation response under both mono- and polychromatic light while varying the amount of spherical aberration. It is thought that chromatic and spherical aberrations are directional cues for the accommodative system and could affect response time, velocity or lag. Spherical aberration is often eliminated in modern contact lenses in order to enhance image quality in the unaccommodated eye. This study was divided into two parts. The first part was done to evaluate the amount of spherical and other Zernike aberrations in the unaccommodated eye when uncorrected and with two types of correction (trial lens and spherical-aberration controlled contact lens) and the second part evaluated the dynamic accommodation responses obtained when wearing each of the corrections under polychromatic and monochromatic conditions. Measurements of accommodation showed no significant differences in time, velocity and lag of accommodation after decreasing the spherical aberration with a contact lens, neither in monochromatic nor polychromatic light. It is unlikely that small to normal changes of spherical aberration in white light or monochromatic mid-spectral light affect directional cues for the accommodative system, not in white light or mid-spectral monochromatic light, since the accommodative response did not show any change.

Resultados preliminares de um algoritmo para ablação de lente de contato personalizada

To develop a computer simulation for customized soft contact lenses in order to correct aberrations of higher order. Using real data from a patient diagnosed with keratoconus, which were measured using a Hartmann-Shack wavefront sensor, the thickness of the contact lenses that compensate these aberrations as well the numbers of pulses required to ablate the lenses were specifically determined for the patient. The maps of correction are presented and the numbers of pulses are calculated, using a 0.5 mm beam width and a 0.3 microm ablation depth. The results shown here are promising, but they should be improved so that the ablation in actual physical systems can reach the desired accuracy.

Fluorescein Pattern Interpretation in Keratoconus

The purpose of this study is to assess the effect of disease severity on how accurately contact lens fluorescein patterns can be interpreted in keratoconus by clinician assessment. Two clinicians evaluated fluorescein patterns on 111 eyes of 60 patients with mild (<45 D, 14 eyes), moderate (45 D to 52 D, 61 eyes,) and severe (>52 D, 36 eyes) keratoconus. The masked clinicians were given six contact lenses in random order, the lens that just cleared the corneal apex (the first definite apical clearance lens), three lenses flatter (in 0.1 mm increments), and two lenses steeper (in 0.1 mm increments) than the first definite apical clearance lens. They ranked the lenses from flattest to steepest, based on the fluorescein patterns. The percentage of lenses correctly ranked was determined using (1) exact match with actual; (2) within 0.1 mm of actual; and (3) within 0.2 mm of actual. Accuracy was assessed as the sum of the squared differences between the actual base curve value and each clinician's ranking. Comparison of the mean percentage correctly ranked and accuracy for each keratoconus severity groups was performed using a mixed linear model. Neither percentage correctly ranked (using any of the three protocols) nor accuracy was found to be related to severity of keratoconus (p > 0.15 for all comparisons). Accuracy of ranking contact lenses in order of base curve radius based on fluorescein pattern assessment by clinicians does not seem to be related to severity of keratoconus. Many factors influence interpretation of fluorescein patterns including all components of the system, fluorescein, tears, cornea, contact lens, external forces, and technique.

Aberration controll with contact lenses

Abstract Purpose: To investigate and compare the reduction in ocular aberrations with standard hydrogel contact lenses (i.e., lenses not designed to control aberrations) and with aberration controlled hydrogel and silicon‐hydrogel contact lenses. Methods: The aberrations with and without contact lenses were measured in 42 subjects between 20 and 37 years of age using a Zywave wave front sensor (B&amp;L). 22 subjects were fitted a standard contact lens and an aberration controlled hydrogel lens. The remaining 20 subjects were fitted aberration controlled silicon‐hydrogel lenses Results: With the standard lens the aberrations were controlled (i.e., close to zero) with a 4.0 mm pupil. Whereas, with both the aberration control lenses the residual spherical aberrations became negative. The reduction in aberrations differed significantly (p&lt;0.05) between all lenses. Conclusions: Since aberration controlled contact lenses in many subjects overcorrect the spherical aberrations when the pupil size is normal (~4.0 mm) we suggest measuring wave front aberrations in each patient both with and without contact lenses in order to achieve the desired effect.