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PubMed1981

Patient preference for a progressive addition multifocal lens (Varilux2) vs a standard multifocal lens design (ST-25).

Patient preference for the Varilux2 lens, a progressive addition multifocal lens, was compared to that of a standard straight-top 25 multifocal. Forty-eight first-time multifocal candidates were fitted with both lens designs, which were then each worn for two three-week periods in succession. The subjects were then asked to state their preference by choosing the lens design they would prefer to continue to wear. Twenty-five of the 48 subjects (52%) preferred the Varilux2 lens design (as compared to the ST-25). The results indicate that the Varilux2 progressive addition lens design is an acceptable method of correction for first time multifocal candidates. The study analyzes patient factors (sex, refractive error, addition power, etc.) in relation to final lens design selection.

Adult↗
PubMed1980

How to prescribe for hunters and marksmen.

Hunters and marksmen have some unusual seeing problems and they differ depending upon the type of gun--shotgun, rifle or pistol. A number of suggestions are made concerning prescribing for these individuals, especially presbyopes. Sighting techniques are discussed, including possible solutions to the difficulty created by crossed dominance.

Dominance, Cerebral↗
PubMedDate not supplied

Monocular diplopia: contact lens related warpage?

1. Always do a corneal topography on difficult-to-fit corneas. Use the Tangential map for a true picture of the overall cornea and the corneal cap. Use the Absolute Scale maps to rule out abnormally steep or flat regions in the cornea and for accurate comparisons of both eyes. 2. Understand that fitting a myopic presbyope with contact lenses will have a subset of problems related to accommodation, opposed to fitting a hyperope. 3. If a contact lens is required to make the corneal surface more regular, consider soft lenses, especially if a monocular is needed. The comfort difference in the contact lens eye versus the normal eye will minimal, compared to a gas-permeable lens fit.

Accommodation, Ocular↗
PubMed1995

Lined multifocal wearers prefer progressive addition lenses.

BACKGROUND: Despite reported successes with progressive addition lenses, lined multifocals remain the lens of choice for previous lined multifocal wearers. METHODS: To explore the feasibility of switching lined multifocal wearers to PALs, in a prospective clinical trial we interviewed 265 lined multifocal wearers, prescribed a new PAL (Varilux Comfort) and then interviewed them again to compare the lens types and patient preferences. RESULTS: PALs ranked significantly higher than lined multifocals for all questions and were preferred by 92 percent of the patients. CONCLUSIONS: PALs should be the lens of choice for previous bifocal wearers.

Adaptation, Ocular↗
PubMed1995

The presbyopic add. I. Magnitude and distribution in a historical context.

The presbyopic addition or 'add' is the (binocular) spherical positive power supplement superimposed on any distance refractive correction to counter near vision difficulties associated with the physiological age-related loss of accommodation and consequent recession of the near point: its necessity is first encountered in middle age. The continuous (linear) ascending trend in near lens power versus increasing age advocated since the seventeenth century is at odds with the twentieth-century clinical observation that there is a deceleration in add requirement beyond an individual's mid-fifties. It is shown here that this difference is reconciled--in broadly qualitative terms if not in magnitude-when typical clinical near addition data are superimposed on the accepted distance hypermetropic refractive base recorded from early middle age onwards: a continuous rising function is produced spanning most of the three decades beyond 40 years of age. This result is considered in the context of the age markings found on certain eighteenth-century antique near vision glasses and the recommendations attached to the self-selection of ready-made reading glasses in the late twentieth century.

Adult↗
PubMed1995

The presbyopic add. III. Influence of the distance refractive type.

The possibility of the distance refractive type-emmetropia, hypermetropia or myopia-influencing the magnitude and rate of change of the presbyopic add does not seem to have received systematic consideration. To address this possibility a further series of transverse clinical data on the progression of the presbyopic add is presented. Analysis of these data reveals the influence of the distance refractive type on the presbyopic progression. Hypermetropes appear to show a two-phase rise in add requirement whereas emmetropes follow a linear and myopes a curvilinear path over the four decades between 41 and 80 years of age. Nevertheless the magnitude of the binocular add requirement at a given age for each of the three refractive types is very similar and all three classes maintain an increasing requirement with advancing age.

Adult↗
PubMed1995

A quantitative and qualitative assessment of the Solitaire Bifocal Contact Lens.

We performed qualitative and quantitative assessments of contact lens performance at 1 and 6 months among 23 patients enrolled in the Solitaire Bifocal Contact Lens Study. Overall satisfaction and comfort at 6 months was rated good to excellent in 83% and 84% of patients, respectively. Daytime acuity at distance and near were rated very good to excellent in 75% and 83% of subjects. Quantitative measurements of distance and near acuities at 1 month revealed 83% and 88% of subjects, respectively, seeing better than or equal to 20/25 or J1. At 6 months there was a moderate decrease in the measured distance acuity. A disparity in glare disability was noted, with 53% of subjects indicating significant glare problems but only 21% of glare tested patients having acuities worse than 20/40. Attrition from the study was highest in the first month and was more common among first-time contact lens users. Overall, this segmented bifocal contact lens is well-tolerated and provides good distance and near vision for presbyopic patients.

Accommodation, Ocular↗
PubMed1995

[Driving with light during the day?].

In various Scandinavian countries the use of headlights during daytime (daytime running light DRL) is obligatory since many years. In Canada all new cars have to be equipped with a daytime running light since 1990. Whether or not in Germany or in the southern neighbouring countries a daytime running light should be used is matter of controversial discussion during the least years. Daytime running light increases the visibility of oncoming cars tremendously. Not only the drivers, but also pedestrians and cyclists profit from this gain of visibility. Especially drivers with poor vision, who will become more and more frequent during the coming years due to the increase of percentage of older drivers, have a specific profit from daytime running light. Potentially negative side-effects of daytime running light are: reduction of visibility of the brake-lights, glare, loss of visibility for pedestrians and cyclists, damage to the retina, increase of fuel consumption. All these arguments are either not crucial or cannot be documented by statistical data. On the other hand the data which are available up to now concerning frequency of accidents in those countries and areas in which daytime running light was used or is used, show a trend, sometimes even a statistical significant reduction of daytime accidents. This reduction is especially pronounced for accidents with pedestrians and cyclists. Overall, there are more and better arguments for using daytime running light, also in Germany. A technical alternative would be an automatic switching of the headlights if horizontal illuminance drops below a specific limit, e.g. 2000-3000 lx. Such an automatic procedure would increase the percentage of cars using headlights in critical situations during daytime.

Accidents, Traffic↗
PubMed1995

Hyperchromatic lenses as potential aids for the presbyope.

It has been suggested that a 'hyperchromatic' lens which enhanced the longitudinal chromatic aberration (LCA) of the eye would increase its depth of focus (DOF) and hence might prove a useful aid to presbyopes who have lost their natural ability to accommodate for different distances. Experiments are described in which high- and low-contrast visual acuity, and contrast sensitivity were measured as a function of object vergence using the naked eye and various levels of effective lens-eye LCA. It was found that doubling the effective lens-eye LCA increased total DOF in the high-contrast acuity task by about 0.5 D, while correcting the ocular LCA reduced DOF by about 0.3 D. On the other hand, enhanced LCA led to some loss in performance in the low-contrast acuity task and in contrast sensitivity.

Adult↗
PubMed1995

Periodic health examination, 1995 update: 3. Screening for visual problems among elderly patients. Canadian Task Force on the Periodic Health Examination.

OBJECTIVE: To provide recommendations to family physicians for screening elderly patients (over 65 years of age) for visual impairment and its common clinical causes. OPTIONS: Visual acuity screening with Snellen sight chart, funduscopy, retinal photography, tonometry and perimetry. OUTCOMES: Delay or prevention of visual deterioration or blindness. EVIDENCE: A MEDLINE search for relevant articles published between January 1986 and December 1993 was undertaken, the bibliographies of the articles were scrutinized for additional articles, and experts were consulted. The highest available level of evidence was used in making recommendations. VALUES: The evidence-based methods and values of the Canadian Task Force on the Periodic Health Examination were used. Preservation of vision was given the highest value in accordance with other guidelines regarding eyesight. BENEFITS, HARMS AND COSTS: Potential benefits are to maintain or improve visual acuity. Potential for harm to patients is minimal. Limited data are available on costs. RECOMMENDATIONS: There is fair evidence to include in the periodic health examination visual acuity testing with a Snellen sight chart and funduscopy or retinal photography in elderly patients with diabetes of at least 5 years' duration (grade B recommendation). The place of funduscopy in the detection of age-related macular degeneration and glaucomatous changes is controversial. For patients at high risk for glaucoma (positive family history, black race, severe myopia or diabetes) it would be prudent to have a periodic assessment by an ophthalmologist. VALIDATION: Recommendations differ from those of the American Academy of Ophthalmology and the American Optometric Association. Recommendations for glaucoma screening are similar to those of the US Preventive Services Task Force. Present recommendations have been reviewed by experts in ophthalmology and optometry. SPONSOR: These guidelines were developed and endorsed by the task force, which is funded by Health Canada and the National Health Research and Development Program. The principal author (C.P.) was supported in part by the Educational Centre for Aging and Health, McMaster University, Hamilton, Ont.

Aged↗
PubMed1995

Comparison of bifocal and progressive addition lenses on aviator target detection performance.

The objective of this project was to determine if the type of presbyopic correction worn by aviators, conventional bifocal versus progressive addition lenses (PAL's), differentially affects aviator visual search performance. Experienced aviators, most with tactical fighter aircraft experience, searched for high-contrast targets under simulated dawn/dust (mesopic) lighting conditions (approximately 3.0 cd/m2) while wearing either a standard bifocal (ST-25) or PAL spectacle correction. Latency of locating high-contrast targets under these viewing conditions was differentially affected by the type of presbyopic correction used. Specifically, compared to a standard bifocal (ST-25), a PAL correction (Varilux Infinity) significantly lowered the time needed to locate static targets at a cockpit instrument viewing distance (83 cm). Accuracy of target location responses was not affected by the type of correction used. In addition, 7 months post-experiment, 7 of the 12 participants (58%) indicated that they used their PAL correction exclusively when flying the T-39 Sabre Liner. Three subjects (25%) used their PAL correction intermittently (primarily at night) when flying and two subjects preferred not to use the PAL's. These results suggest that relative to bifocals, speed of responding to static targets at intermediate viewing distances may be improved by wearing PAL's, and that subjects were able to adapt to PAL lenses quickly in a laboratory setting, using them later in a functional aviation environment.

Adult↗
PubMed1995

Clinical experience with the SimulVue soft bifocal contact lens.

We fit the SimulVue bifocal contact lens, a soft lens with a simultaneous vision design, in 30 presbyopic patients. The lens has a central near correction surrounded by a concentric peripheral distance correction. Patients were evaluated prior to inclusion in the study and followed for a period of 1 year. The evaluation included visual acuity and contrast sensitivity at both distance and near with and without lenses. In addition, patients completed a questionnaire at the end of the study. At the end of 1 year, 16 of 30 (53%) patients were successfully wearing the contact lenses. Of these, 13 of 16 patients (81%) achieved J2 or better near vision, and 10 of 16 (63%) achieved 20/25 or better distance vision in both eyes. Greater reduction of contrast sensitivity occurred at near, with only 38% of patients (6/16) retaining their normal contrast sensitivity; whereas at distance, 81% of patients (13/16) retained normal contrast sensitivity. Fourteen patients failed to complete the study. The most common reasons cited were poor vision at distance (6/14, 43%), poor vision at near (6/14, 43%), and ghosting of images (4/14, 29%). We believe that the SimulVue contact lens is a viable option for the correction of many presbyopic patients.

Adult↗