The Experts below are selected from a list of 783 Experts worldwide ranked by ideXlab platform

Ravi C. Bakaraju - One of the best experts on this subject based on the ideXlab platform.

  • Short-Term Adaptation of Accommodative Responses in Myopes Fitted With Multifocal Contact Lenses.
    Eye & Contact Lens: Science & Clinical Practice, 2018
    Co-Authors: Jerome Ozkan, Cathleen Fedtke, Jiyoon Chung, Varghese Thomas, Ravi C. Bakaraju
    Abstract:

    Objectives:To investigate whether adaptation of accommodative responses occurred in non-presbyopic myopes fitted with four Multifocal Contact Lens (MFCL) designs.Methods:Prospective, subject-masked clinical investigation comprising 40 experienced myopic Lens wearers (18–25 years) fitted bilaterally

  • Impact of Spherical Aberration Terms on Multifocal Contact Lens Performance.
    Optometry and vision science : official publication of the American Academy of Optometry, 2017
    Co-Authors: Cathleen Fedtke, Klaus Ehrmann, Varghese Thomas, Jennifer Sha, Ravi C. Bakaraju
    Abstract:

    ABSTRACTPurposeTo investigate the impact of the primary (PSA) and secondary (SSA) spherical aberration terms on visual performance (VP) in presbyopes, as measured using Multifocal (MFCL) soft Contact Lenses on eye.MethodsSeventeen presbyopes (age: 55.1 ± 6.9 years) wore seven commercial Lenses (four

  • Predicting Short-term Performance of Multifocal Contact Lenses.
    Eye & contact lens, 2017
    Co-Authors: Jennie Diec, Daniel Tilia, Thomas Naduvilath, Ravi C. Bakaraju
    Abstract:

    To investigate if initial Multifocal Contact Lens (MFCL) performance predicts short-term dispensing performance. A retrospective analysis of 55 participants (Px) in a masked, crossover, clinical trial, using ACUVUE OASYS for Presbyopia and AIR OPTIX AQUA Multifocal. Subjective questionnaires were administered at the following instances: initial fitting, two take home questionnaires (THQ) completed between days 2 and 4 and at assessment, ≥5 days after fitting. Questionnaires included vision clarity and lack of ghosting at distance, intermediate and near at day/night time points rated on a 1 to 10 (1-step, 10 most favorable) rating scale. Vision stability, vision while driving, overall vision satisfaction, willingness to purchase and comfort, as well as acuity-based measures were also collected. There were no statistical differences in comfort and vision at all distances, in vision stability or driving at either time points between THQ and assessment (P>0.05). However, there was a statistical decline in subjective overall vision satisfaction and comfort between fitting and assessment visits (P

  • Inherent ocular spherical aberration and Multifocal Contact Lens optical performance.
    Optometry and vision science : official publication of the American Academy of Optometry, 2010
    Co-Authors: Ravi C. Bakaraju, Klaus Ehrmann, Eric B. Papas
    Abstract:

    ABSTRACTPurpose.The role of inherent spherical aberration (SA) in the optical performance of presbyopic eyes corrected with simultaneous vision Multifocal Contact Lenses was investigated.Methods.Presbyopic schematic eyes were modeled with partial accommodative function to represent 45- and 55-year o

  • A theoretical design of gradient index Multifocal Contact Lens for correcting presbyopia and an attempt to elicit its performance using ray tracing
    Ophthalmic Technologies XIX, 2009
    Co-Authors: Ravi C. Bakaraju, Klaus Ehrmann, Eric B. Papas
    Abstract:

    We propose a novel theoretical design of gradient index (GRIN) Multifocal Contact Lens (MFCL) to compensate presbyopia and make predictions regarding its performance on a schematic model eye and to compare its performance with conventional aspheric progressive MFCL.

Sally Dillehay - One of the best experts on this subject based on the ideXlab platform.

  • Case Series Analysis of Myopic Progression Control With a Unique Extended Depth of Focus Multifocal Contact Lens.
    Eye & contact lens, 2018
    Co-Authors: Jeffrey Cooper, Brett Oʼconnor, Ronald Watanabe, Randall Fuerst, Sharon Berger, Nadine Eisenberg, Sally Dillehay
    Abstract:

    OBJECTIVES To determine the rate of myopia progression in children fit with a commercially available extended depth of focus (center distance) Multifocal soft Contact Lens with attributes theoretically expected to slow the progression of myopia. METHODS A retrospective case series analysis of 32 patients (ages 6-19 years, mean 10.98±2.95) from 10 practice locations was performed. At initial presentation, 44% wore spectacles, 37.5% spherical soft Contact Lenses, 15.6% a different soft Multifocal Contact Lens, and 3% orthokeratology Lenses. All participants showed progression of at least -0.50 diopter with current corrections and were fit with an extended depth of focus (center distance) Multifocal soft Contact Lens (NaturalVue Multifocal 1 Day Contact Lenses; Visioneering Technologies, Inc., Alpharetta, GA). Follow-up time was 6 to 25 months (mean: 10.94±4.76). RESULTS Reductions in the annualized rate of myopic progression from -0.85 D per year ±0.43 D to -0.04 D per year ±0.18 D (P

  • case series analysis of myopic progression control with a unique extended depth of focus Multifocal Contact Lens
    Eye & Contact Lens-science and Clinical Practice, 2017
    Co-Authors: Jeffrey Cooper, Brett Oʼconnor, Ronald Watanabe, Randall Fuerst, Sharon Berger, Nadine Eisenberg, Sally Dillehay
    Abstract:

    OBJECTIVES To determine the rate of myopia progression in children fit with a commercially available extended depth of focus (center distance) Multifocal soft Contact Lens with attributes theoretically expected to slow the progression of myopia. METHODS A retrospective case series analysis of 32 patients (ages 6-19 years, mean 10.98±2.95) from 10 practice locations was performed. At initial presentation, 44% wore spectacles, 37.5% spherical soft Contact Lenses, 15.6% a different soft Multifocal Contact Lens, and 3% orthokeratology Lenses. All participants showed progression of at least -0.50 diopter with current corrections and were fit with an extended depth of focus (center distance) Multifocal soft Contact Lens (NaturalVue Multifocal 1 Day Contact Lenses; Visioneering Technologies, Inc., Alpharetta, GA). Follow-up time was 6 to 25 months (mean: 10.94±4.76). RESULTS Reductions in the annualized rate of myopic progression from -0.85 D per year ±0.43 D to -0.04 D per year ±0.18 D (P<0.00000) OD, -0.90 D per year ±0.57 D to -0.03 D per year ±0.17 D (P<0.00000) OS were observed. These data represent a reduction of 95.4% OD and 96.25% OS. Approximately 98.4% of the children showed reduction of annualized myopic progression; 91% showed a decrease of 70% or greater. Overall, 81.25% showed complete halting of myopic progression, including 6.25% demonstrating myopic regression. CONCLUSIONS This unique extended depth of focus (center distance) daily disposable Multifocal Contact Lens was effective in slowing myopic progression in these children. These findings add to the growing evidence that center distance Multifocal soft Contact Lenses may slow the progression of myopia.

Michel Guillon - One of the best experts on this subject based on the ideXlab platform.

  • Real World Through Focus Curve of a New Multifocal Contact Lens
    Investigative Ophthalmology & Visual Science, 2016
    Co-Authors: Michel Guillon, Kathryn Dumbleton, Trisha Patel, Tom Karkkainen, Kurt Moody, Ron Clark
    Abstract:

    Purpose : The Through Focus Curve (TFC) is often used to characterise visual performance of Multifocal Contact Lenses (MCL) and intra ocular Lenses over a range of defocus. Typically negative Lenses are used to produce vergences but this requires accurate Lens centration and trial Lenses may interfere with binocularity. The objective was to characterize a new MCL using a new clinical test paradigm, measuring visual acuity (VA) at the actual distances of interest, allowing normal convergence and both binocular and monocular measurements. Methods : Monocular, binocular (B) and binocular summation (BS) TFCs were obtained by measuring logMAR VA at 6 distances (40cm, 50cm, 67cm, 1m, 2m & 4m) for 3 luminances (250cd/m2 daytime and computer use, 50cd/m2 indoor evening & 2.5cd/m2 night driving). The measurements were made with OTG-i Vision using a 4K screen at distance, an iPad 2 Air (retina) for intermediate and an iPad mini (retina) for near, all driven by a dedicated App. The study MCL was 1-DAY ACUVUE® MOIST Brand Multifocal. The study population (age 51.7 ± 7.37) comprised 7 low, 10 medium and 13 high addition subjects. Results : (i) Mean BVA at 250cd/m2 was 20.20) at all distances. The best BVA was achieved at 2m (-0.19 logMAR 20/13) and the lowest at 40cm (-0.04 logMAR 20/18); (ii) Mean BVA at 50cd/m2 was lower than at 250cd/m2 by 1 line at distance (+0.1 logMAR), 1.2 lines at intermediate (+0.12 logMAR) and 1.4 lines at near (+0.14 logMAR) maintaining a balanced performance for all distances; (iii) Mean BVA at 2.5cd/m2 was biased for distance, with 2.5 lines (0.25 logMAR) loss compared with 250cd/m2 giving a mean VA of 20/25; (iv) Differences in VA between dominant and non-dominant eyes were small, at most 1/3 of a line (mean differences -0.025 to + 0.029 logMAR); with a trend to favour the dominant eye at distance and the non-dominant eye at near; (v) BS was most marked at distance (mean -0.01 to -0.04 logMAR), demonstrating that the MCL were not biased towards modified monovision maintaining binocularity. Conclusions : This novel “real world” clinical technique was able to fully characterise the TFC performance of the study MCL, demonstrating excellent performance at high luminance while maintaining balanced VA at all distances at medium luminance and a bias towards distance at low luminance (night driving). In addition monocular and binocular VA measurements have confirmed binocular summation with the MCL. This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

  • visual performance of a multi zone bifocal and a progressive Multifocal Contact Lens
    The CLAO journal : official publication of the Contact Lens Association of Ophthalmologists Inc, 2002
    Co-Authors: Michel Guillon, Cecile Maissa, Philip Cooper, Karine Girardclaudon, Timothy R Poling
    Abstract:

    Purpose. This study measured the relative visual performance of two planned-replacement soft Contact Lenses for presbyopic correction: a multi-zone bifocal (ACUVUE, Johnson & Johnson Vision Care, Jacksonville, FL) Contact Lens and a progressive Multifocal (Focus Progressives, CIBA Vision, Duluth, GA) Contact Lens. Methods. This was a randomized, double-masked, non-dispensing cross-over study. Visual performance was evaluated by log of minimal angle of resolution (LogMAR) measurement of visual acuity (VA) under a representative range of luminances (distance 250 candela[cd]/m 2 and 2.5 cd/m 2 , near 250 cd/m 2 and 50 cd/m 2 ) and contrasts (90% and 10%). The 45 presbyopic subjects were equally distributed in three subgroups according to spectacle addition: low presbyopia (+0.75D to +1.25D); medium presbyopia (+1.50D to +1.75D); and high presbyopia (+2.00 to +2.50D). Results. Statistically significant differences were found in overall distance VA (P<0.001; average of four luminance-contrast combinations) and low-luminance distance VA (P=0.004), which, in both cases, favored the multi-zone bifocal Lens design. For low presbyopes, the multi-zone bifocal design produced a significantly better visual performance (P=0.004) than did the progressive Multifocal. Overall near VA was also significantly better (P<0.001) with the multi-zone bifocal Lens. Differences in near VA were particularly marked in high-luminance conditions (high and low contrasts combined) and were statistically significant for all three presbyopic subgroups. Conclusions. Visual acuity performance with the multi-zone bifocal was superior overall to that achieved with the progressive Multifocal design. This study suggests that having only one addition is detrimental to performance with the progressive Multifocal Lens, particularly for low presbyopes.

  • Visual performance of a multi-zone bifocal and a progressive Multifocal Contact Lens.
    The CLAO journal : official publication of the Contact Lens Association of Ophthalmologists Inc, 2002
    Co-Authors: Michel Guillon, Cecile Maissa, Philip Cooper, Karine Girard-claudon, Poling Timothy R
    Abstract:

    Purpose. This study measured the relative visual performance of two planned-replacement soft Contact Lenses for presbyopic correction: a multi-zone bifocal (ACUVUE, Johnson & Johnson Vision Care, Jacksonville, FL) Contact Lens and a progressive Multifocal (Focus Progressives, CIBA Vision, Duluth, GA) Contact Lens. Methods. This was a randomized, double-masked, non-dispensing cross-over study. Visual performance was evaluated by log of minimal angle of resolution (LogMAR) measurement of visual acuity (VA) under a representative range of luminances (distance 250 candela[cd]/m 2 and 2.5 cd/m 2 , near 250 cd/m 2 and 50 cd/m 2 ) and contrasts (90% and 10%). The 45 presbyopic subjects were equally distributed in three subgroups according to spectacle addition: low presbyopia (+0.75D to +1.25D); medium presbyopia (+1.50D to +1.75D); and high presbyopia (+2.00 to +2.50D). Results. Statistically significant differences were found in overall distance VA (P

Jeffrey Cooper - One of the best experts on this subject based on the ideXlab platform.

  • Case Series Analysis of Myopic Progression Control With a Unique Extended Depth of Focus Multifocal Contact Lens.
    Eye & contact lens, 2018
    Co-Authors: Jeffrey Cooper, Brett Oʼconnor, Ronald Watanabe, Randall Fuerst, Sharon Berger, Nadine Eisenberg, Sally Dillehay
    Abstract:

    OBJECTIVES To determine the rate of myopia progression in children fit with a commercially available extended depth of focus (center distance) Multifocal soft Contact Lens with attributes theoretically expected to slow the progression of myopia. METHODS A retrospective case series analysis of 32 patients (ages 6-19 years, mean 10.98±2.95) from 10 practice locations was performed. At initial presentation, 44% wore spectacles, 37.5% spherical soft Contact Lenses, 15.6% a different soft Multifocal Contact Lens, and 3% orthokeratology Lenses. All participants showed progression of at least -0.50 diopter with current corrections and were fit with an extended depth of focus (center distance) Multifocal soft Contact Lens (NaturalVue Multifocal 1 Day Contact Lenses; Visioneering Technologies, Inc., Alpharetta, GA). Follow-up time was 6 to 25 months (mean: 10.94±4.76). RESULTS Reductions in the annualized rate of myopic progression from -0.85 D per year ±0.43 D to -0.04 D per year ±0.18 D (P

  • case series analysis of myopic progression control with a unique extended depth of focus Multifocal Contact Lens
    Eye & Contact Lens-science and Clinical Practice, 2017
    Co-Authors: Jeffrey Cooper, Brett Oʼconnor, Ronald Watanabe, Randall Fuerst, Sharon Berger, Nadine Eisenberg, Sally Dillehay
    Abstract:

    OBJECTIVES To determine the rate of myopia progression in children fit with a commercially available extended depth of focus (center distance) Multifocal soft Contact Lens with attributes theoretically expected to slow the progression of myopia. METHODS A retrospective case series analysis of 32 patients (ages 6-19 years, mean 10.98±2.95) from 10 practice locations was performed. At initial presentation, 44% wore spectacles, 37.5% spherical soft Contact Lenses, 15.6% a different soft Multifocal Contact Lens, and 3% orthokeratology Lenses. All participants showed progression of at least -0.50 diopter with current corrections and were fit with an extended depth of focus (center distance) Multifocal soft Contact Lens (NaturalVue Multifocal 1 Day Contact Lenses; Visioneering Technologies, Inc., Alpharetta, GA). Follow-up time was 6 to 25 months (mean: 10.94±4.76). RESULTS Reductions in the annualized rate of myopic progression from -0.85 D per year ±0.43 D to -0.04 D per year ±0.18 D (P<0.00000) OD, -0.90 D per year ±0.57 D to -0.03 D per year ±0.17 D (P<0.00000) OS were observed. These data represent a reduction of 95.4% OD and 96.25% OS. Approximately 98.4% of the children showed reduction of annualized myopic progression; 91% showed a decrease of 70% or greater. Overall, 81.25% showed complete halting of myopic progression, including 6.25% demonstrating myopic regression. CONCLUSIONS This unique extended depth of focus (center distance) daily disposable Multifocal Contact Lens was effective in slowing myopic progression in these children. These findings add to the growing evidence that center distance Multifocal soft Contact Lenses may slow the progression of myopia.

Chia-wei Yu - One of the best experts on this subject based on the ideXlab platform.

  • compensating additional optical power in the central zone of a Multifocal Contact Lens forminimization of the shrinkage error of the shell mold in the injection molding process
    Applied Optics, 2018
    Co-Authors: Lien T. Vu, Chao-chang A. Chen, Chia-wei Yu
    Abstract:

    This study aims to develop a compensating method to minimize the shrinkage error of the shell mold (SM) in the injection molding (IM) process to obtain uniform optical power in the central optical zone of soft axial symmetric Multifocal Contact Lenses (CL). The Z-shrinkage error along the Z axis or axial axis of the anterior SM corresponding to the anterior surface of a dry Contact Lens in the IM process can be minimized by optimizing IM process parameters and then by compensating for additional (Add) powers in the central zone of the original Lens design. First, the shrinkage error is minimized by optimizing three levels of four IM parameters, including mold temperature, injection velocity, packing pressure, and cooling time in 18 IM simulations based on an orthogonal array L18 (21×34). Then, based on the Z-shrinkage error from IM simulation, three new Contact Lens designs are obtained by increasing the Add power in the central zone of the original Multifocal CL design to compensate for the optical power errors. Results obtained from IM process simulations and the optical simulations show that the new CL design with 0.1 D increasing in Add power has the closest shrinkage profile to the original anterior SM profile with percentage of reduction in absolute Z-shrinkage error of 55% and more uniform power in the central zone than in the other two cases. Moreover, actual experiments of IM of SM for casting soft Multifocal CLs have been performed. The final product of wet CLs has been completed for the original design and the new design. Results of the optical performance have verified the improvement of the compensated design of CLs. The feasibility of this compensating method has been proven based on the measurement results of the produced soft Multifocal CLs of the new design. Results of this study can be further applied to predict or compensate for the total optical power errors of the soft Multifocal CLs.

  • Optical design of soft Multifocal Contact Lens with uniform optical power in center-distance zone with optimized NURBS
    Optics Express, 2018
    Co-Authors: Lien T. Vu, Chao-chang A. Chen, Chia-wei Yu
    Abstract:

    This study aims to develop a new optical design method of soft Multifocal Contact Lens (CLs) to obtain uniform optical power in large center-distance zone with optimized Non-Uniform Rational B-spline (NURBS). For the anterior surface profiles of CLs, the NURBS design curves are optimized to match given optical power distributions. Then, the NURBS in the center-distance zones are fitted in the corresponding spherical/aspheric curves for both data points and their centers of curvature to achieve the uniform power. Four cases of soft CLs have been manufactured by casting in shell molds by injection molding and then measured to verify the design specifications. Results of power profiles of these CLs are concord with the given clinical requirements of uniform powers in larger center-distance zone. The developed optical design method has been verified for Multifocal CLs design and can be further applied for production of soft Multifocal CLs.