Edward S. Bennett

Contact lens correction of presbyopia.

The contact lens wearing presbyopic population is underserved worldwide. There are several available options, including single vision contact lenses and spectacle over‐correction for near, monovision, rigid gas permeable (GP) multifocal and bifocal lens designs and soft bifocal lens designs. This paper presents an overview of the latest research and clinical experience as it pertains to these forms of correction. Recent comparative studies concluded that contact lens multifocals perform better in many different forms of visual measurements, in some cases performing similar to best spectacle correction, than monovision wearers. The future appears to be very promising for multifocal GP and soft lens modalities.

Visual Performance of Subjects Wearing Presbyopic Contact Lenses

Purpose. The purpose of this study is to assess the visual performance of subjects wearing gas-permeable (GP) multifocal contact lenses, soft bifocal contact lenses, GP monovision lenses and spectacles. Methods. The study included 32 subjects between the ages of 42 and 65 years wearing GP monovision, the Acuvue Bifocal (Vistakon), the Essentials GP Multifocal (Blanchard), and progressive addition lenses (PAL; spectacles group). There were eight subjects in each of these groups who were already wearing these modalities. Binocular low (18%) and high (95%) contrast acuities were recorded using the Bailey-Lovie chart; binocular contrast sensitivity from 1.5 to 18 cycles per degree (cpd) measured with the Vistech VCTS 6500 system, and monocular glare sensitivity at three luminance settings (400, 100, and 12 foot lamberts) was measured using the brightness acuity tester (BAT). Binocular near visual task performance (a modified version of letter counting method used in previous presbyopic studies) was also assessed. Results. For the contact lens-wearing groups, subjects wearing GP multifocals provided the best binocular high and low contrast acuity followed by soft bifocal wearers. There was relative parity between the binocular high and low contrast acuity with PAL and GP multifocal wearers. Monovision acuity, measured binocularly, was determined to be lower than the other three groups with this difference being most significant with high contrast acuity. Among contact lens-wearing groups, it was observed that GP multifocal lens wearers experienced the lowest amount of monocular disability glare followed by soft bifocal wearers and monovision wearers. Subjects wearing soft bifocal lenses and monovision demonstrated slightly reduced binocular contrast sensitivity at all spatial frequencies. In the contact lens groups, GP multifocal lens wearers had the highest binocular contrast sensitivity at all spatial frequencies, on parity with PAL wearers, except at the highest spatial frequency (18 cpd) at which PAL wearers had better vision. Error scores for the binocular near visual task performance between the four groups revealed subjects with GP multifocal lenses and PAL wearers to have the least errors, followed by monovision users and then soft bifocal wearers with the most errors. Conclusion. Subjects wearing GP multifocals, soft bifocals, monovision, and PAL spectacles have good binocular contrast sensitivity, satisfactory binocular low and high contrast acuity, and increased sensitivity to glare. Presbyopic subjects requiring the use of contact lenses under dim light levels could benefit from GP multifocal lenses. Contrast and glare sensitivity evaluations provide significant information regarding the visual performance of the presbyopic contact lenses and should be included in regular presbyopic contact lens fitting.

Clinical Investigation of the Paraperm Ew Rigid Gas-permeable Contact Lens

ABSTRACT Paraperm EW is a high oxygen flux silicone/acrylate rigid lens material currently under clinical investigation for extended wear. The purpose of this paper is to report the clinical findings after 12 months of a 2‐year investigation of 18 patients fitted with this material. Fifteen were successfully wearing Paraperm EW lenses at 1 year. The only significant clinical finding was keratometric flattening at the 1‐month visit. It was concluded that the Paraperm EW lens was durable, comfortable, and provided excellent visual acuity during the course of this investigation without inducing any of the ocular complications sometimes associated with extended wear of hydrogel lenses.

Effect of topical anesthetic use on initial patient satisfaction and overall success with rigid gas permeable contact lenses.

Background. Rigid gas permeable (RGP) contact lenses have numerous benefits; however, RGP lens use is not increasing in the United States. An important factor for this trend has been initial comfort. Studies have demonstrated that how RGPs are presented to patients, in addition to lens design, can play an important role in the initial comfort process. Another important factor could be the use of a topical anesthetic during the fitting and dispensing visits. The purpose of this study was to use a multicenter format to determine if topical anesthetic use increased the likelihood of patient satisfaction and success. Methods. A total of 80 subjects, with no previous rigid lens wear experience, was entered into this 1 -month study, including 20 subjects from each of 4 institutions. Subjects were randomly divided into the following two groups: (A) anesthetic or (B) placebo, with the former group receiving one drop of a topical anesthetic before lens insertion at both the diagnostic fitting and dispensing visits, whereas the latter group received a placebo. Subjects completed a questionnaire on their perception of rigid lens wear both immediately before fitting and at the 1-month visit. After diagnostic fitting with rigid lenses, subjects completed an adaptation questionnaire after 15 min, 1 week, 2 weeks, and 1 month of lens wear. Results. Seventy of the 80 subjects completed the study and, of the 10 subjects who discontinued, 8 were in the placebo group. In all categories evaluated, the anesthetic group experienced a more optimum adaptation experience at each visit vs. the placebo group. Specifically, overall comfort was rated significantly higher at both dispensing and 2 weeks. In addition, the anesthetic group exhibited significantly greater overall satisfaction with rigid lens wear at 2 and 4 weeks. Also, the anesthetic group perceived their adaptation, sensitivity, and adaptation time to be significantly better at the 1 -month visit. There was no significant difference in corneal staining between these two groups at each visit, with the exception of a greater amount of staining in the central quadrant for the placebo group at the 1 -month visit. Conclusions. The use of a topical anesthetic at the fitting and dispensing visits for first-time wearers of RGP lenses resulted in significantly fewer dropouts, improved initial comfort, an enhanced perception of the adaptation process, and greater overall satisfaction after 1 month of lens wear as compared to the use of a nonanesthetizing placebo at those visits. This result, in combination with both presenting RGP lenses in a nonthreatening manner and optimizing the lens design and fitting relationship, should result in a positive adaptation process and successful wear of RGP contact lenses.

Effect of patient personality profile and verbal presentation on successful rigid contact lens adaptation, satisfaction and compliance.

Background. Rigid gas permeable (RGP) lenses have numerous benefits, including quality of vision, ocular health, and reduction of myopic progression in young people. Nevertheless, RGP lens use is not increasing in the United States. It is possible that certain patient personality characteristics and/or how a practitioner presents RGP lenses to a new patient may affect satisfaction and success. The purpose of this study was to evaluate the effect of individual patients personality and the practitioners method of presenting RGP lenses to new patients on their ability to adapt to these lenses. Methods. Forty-nine subjects, all noncontact lens wearers, were entered into this 1-month study, which was conducted at both the University of Missouri-St. Louis School of Optometry and the Pacific University College of Optometry. All subjects initially completed standardized questionnaires pertaining to locus of control, openness to new experiences, and motivation/expectations. After diagnostic fitting with a RGP lens material, the subjects were placed into one of the following three groups: (1) Fear-Arousing Non-Enthused; (2) Neutral Content Non-Enthused; or (3) Neutral Content Enthused. They observed one of three video presentations on RGP lens wear. Subjects submitted daily questionnaires providing their evaluation of such factors as comfort, wearing time, and handling. Results. The results showed that there was a significant difference (x2=6.99; p<0.05) among the different groups in the number of dropouts: 6/19 with the Fear-Arousing Non-Enthused group, 2/17 with the Neutral Content Non-Enthused group, and 0/13 with the Neutral Content Enthused group. There was also a significant difference (ANOVA F=4.1, p<0.05) among the groups on compliance, with the Neutral Content Enthused group demonstrating greater compliance. In terms of satisfaction, there was no significant difference among presentation groups. Conclusion. It was concluded that the method of presentation is important for successful RGP contact lens wear. If presented with genuine interest and a positive and realistic attitude, patients are more likely to succeed in RGP lens wear during the initial critical period.

Contrast sensitivity with presbyopic contact lenses

The purpose of the work was to assess the contrast sensitivity function of individuals wearing gas permeable (GP) multifocal contact lenses, soft bifocal contact lenses, and GP monovision lenses. Twenty-six females and six males between the ages of 42 and 65 participated in this study. The study included subjects wearing monovision (N = 8), the Acuvue Bifocal (Johnson & Johnson) (N = 8), Essential GP Multifocal (Blanchard) lenses (N = 8) and progressive addition spectacle lenses (PAL) (N = 8), with PAL wearers forming the control group. Measurements of binocular contrast sensitivity were obtained using the VISTECH 6500 system. Thresholds for each spatial frequency were fit to the equation CS(k) = ak exp(−bk) [1 + c exp(bk)]−1/2, to describe the human contrast sensitivity function. The area under the contrast sensitivity function (CSF) curve was calculated for all four groups and compared. An index of performance was obtained, which was defined as the ratio of CSF with the contact lens correction to the CSF with spectacles. Of the contact lens wearing groups, GP multifocal contact lens wearers had the highest contrast sensitivity at all the spatial frequencies. Soft bifocal contact lens wearers exhibited higher contrast sensitivity than monovision wearers at all spatial frequencies. Subjects wearing GP multifocals had the largest area under the CSF; followed by those wearing soft bifocals, with monovision wearers having the smallest area. GP multifocals have the best visual function at 0.98, soft bifocals have an index of 0.65 and monovision has an index of 0.59. This study quantifies the visual performance of the three lens systems by measuring the area under the CSF curve. In addition, it provides indices of visual function with the contact lenses that will be helpful for analyses and comparisons in future studies.

VISION CHANGES, INTELLIGENCE, AND AGING: PART 2

Abstract The effect of vision changes commonly associated with aging on intellectual performance is a relatively neglected topic in the literature. The purpose of this article is to review common visual changes with age and examine what effects they have on ones ability to function. In addition, variables related to intellectual functioning and their relationship with aging will be discussed.

Clinical Evaluation of Large Diameter Rigid-gas Permeable Versus Soft Toric Contact Lenses for the Correction of Refractive Astigmatism. A Multicenter Study

Purpose: This study aims to address the clinical performance of a large diameter rigid gas permeable lens (LRGP) in a group of subjects with low-to-moderate (0.75–2.75 D) refractive astigmatism. An additional goal was to determine whether soft toric or LRGP contact lenses performed better objectively in the correction of astigmatism and to determine which modality is preferred by subjects. Methods: This was a multisite prospective cross-over clinical study. Ten asymptomatic contact lens wearers per site (four university clinics) were recruited and randomly assigned to group A or group B. Group A was assigned to start wearing Comfilcon A soft toric lens first, for two weeks, and then crossed over to LRGP lenses (Boston XO, 14.3 mm diameter miniscleral lens). Group B initially wore LRGP lenses and then crossed over to soft toric lenses. For each type of lens worn, low-contrast and high-contrast visual acuity (VA) were evaluated at distance. At the conclusion of the study, after two months, all subjects completed a questionnaire in which they were asked to indicate their preference for one type of lens (soft toric or LRGP) and to rate the quality of vision in day-to-day activities. Results: Thirty-six of 38 (94.7%) subjects completed the study with 75% preferring the vision of the LRGP lens as compared to the soft toric lenses worn in the study. 52.7% expressed a preference to continue with this modality despite only 38.8% reporting that these LRGP lenses are easy or very easy to handle. Wear time, subjective comfort, and subjective vision ratings exhibited no significant difference between the two groups. Conclusions: In a population of asymptomatic contact lens wearers, LRGP lenses can be considered as a good alternative to soft toric lenses for the correction of refractive astigmatism.

An evaluation of the 8.4 mm and the 8.8 mm base curve radii in the Ciba NewVe vs. the Vistakon Acuvue

Abstract As practitioners, we have often fit soft contact lenses using the medium or flattest base curve radius as our first choice of base curve radius; however, it is important to realize that identical base curve radii in different lens materials may fit differently. In addition, the flattest or medium base curve radius may not always provide optimal comfort. When fitting soft lenses, it is important to achieve a good fit and provide good performance. In this study, completed at the University of Missouri-St. Louis, School of Optometry, the NewVue (Ciba Vision Corp.) and the Acuvue (Vistakon) 8.4 and 8.8 mm base curve radii were compared based on comfort, visual acuity, contrast sensitivity, lens movement, and ease of handling in a double-blind study. The results showed that subjects performed similarly among NewVue and Acuvue lenses. The Acuvue 8.4 mm base curve radius was perceived as being more comfortable than the patients current contact lenses and showed optimal centration and best distance Snellen visual acuity. The Acuvue 8.8 mm base curve radius showed optimal lens movement. The NewVue 8.4 mm base curve radius showed optimal lens movement and demonstrated excellent handling and lens centration. The NewVue 8.8 mm base curve radius demonstrated excellent lens handling. When fitting a disposable contact lens candidate, our first choice for lens selection would be the Acuvue 8.8 mm base curve radius or the NewVue 8.4 mm base curve radius. If these lenses are not adequate, appropriate changes may be made.

RGP lens power change with abrasive cleaner use

The introduction of the so-called superpermeable rigid gas permeable (RGP) lens materials has greatly reduced contact lens complications associated with hypoxia. In addition, the incorporation of fluorine into most RGP lens materials has permitted higher siloxane contenttherefore, higher oxygen permeability-with minimal compromise in surface wettability. The important clinical problem presented by this new generation of fluorosilicone/acrylate lens materials, however, is stability. Reports of warpage,iV2 flexure,3 and radical flattening4 with high Dk RGP lens materials have been reported in the literature due to the softness and flexibility of these materials relative to PMMA and low Dk RGP polymers. These stability-related complications often result in unacceptable visual acuity and/or a compromised lensto-cornea fitting relationship. This is especially problematic in former PMMA wearers who often maintain the same vigorous cleaning technique with their RGPs; the result is a much higher incidence of warpage than present with nonPMMA lens wear.4 The purpose of this article is to report on another related RGP material and patient compliancerelated problem-specifically, an increase in minus power occurring over time with an abrasive cleaner in combination with excessive digital pressure.