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PubMed2000

Presbyopic contact lenses.

The year 1999 will be remembered as the one in which a very successful bifocal soft contact lens was finally available for the millions of presbyopic and emerging presbyopic Baby Boomers. As a result, soft bifocal fits almost tripled in 1 year. The introduction in 1999 of new daily disposable and new high oxygen permeable extended wear soft contact lenses will give practitioners more options to be successful with monovision. Tips from several practitioners on being successful with bifocal soft lenses are given. It cannot be stressed enough, however, that for patients with presbyopia to be successful with these lenses, they must be willing to compromise somewhat on the quality of vision they remember as a 30-year-old.

Contact Lenses, Hydrophilic↗
PubMed2004

Advances in phakic intraocular lenses: indications, efficacy, safety, and new designs.

PURPOSE OF REVIEW: The recent evolution of phakic intraocular lenses (PIOLs) has made this refractive surgical technique safer, very predictable, and effective. Due to these reasons, PIOLs have been expanding the horizon of their indications. The aim of this review is to update the reader in the recent advances reported on the topic during the year 2003. RECENT FINDINGS: The most recent progress has been made towards decreasing the incision size down to 3 mm or less for all PIOLs models to avoid pupil ovalling in angle-supported designs with new biomaterials or exchangeable haptics, and to decrease the incidence of cataract induction in posterior chamber models with modified designs and better sizing. High-order aberrations and the quality of vision are improved with PIOLs. The main limitation for the further development of PIOLs is the lack of adequate diagnostic imaging techniques to perform a precise preoperative study of the anterior segment anatomy. Emerging diagnostic technologies based on the use of very high frequency (100 MHz) ultrasound and optical coherence tomography seem to have a most important role in the future development of PIOLs defining preoperatively the most adequate anatomic conditions for each design. PIOLs offer today an excellent alternative for the correction of high and moderate myopia, hyperopia, and astigmatism. Emerging indications, still under investigation, include presbyopia and pediatric anisometropic amblyopia. SUMMARY: Due to their advantages for quality of vision and the increased knowledge on their safety, as well as the evidence of their predictability, PIOLs are expected to largely increase their clinical use as a refractive surgical technique in the coming years.

Anterior Chamber↗
PubMed2003

Successful monovision contact lens wearers refitted with bifocal contact lenses.

PURPOSE: Should successful monovision contact lens wearers be refitted with bifocal lenses? METHODS: Fifty current monovision lens wearers were fitted with ACUVUE Bifocal contact lenses (Johnson & Johnson Vision Care, Jacksonville, FL). Visual function and subjective vision ratings were assessed with habitual monovision lenses at the first visit and then were repeated at the end of 6 months while wearing bifocal lenses. Lens preference was determined at the end of the 6-month study, and the subjects were called 1 year later to repeat the lens preference questionnaire. RESULTS: Forty (80%) subjects completed the 6-month study; nine discontinued for visual reasons. At the end of 6 months of wear, 68% preferred bifocal lenses and 25% preferred monovision. Of the subjects who were contacted a year later, 53% were still wearing bifocal lenses. High-contrast visual acuity and letter contrast sensitivity at distance was the same for monovision and bifocal lenses, but low-contrast acuity was better with monovision. Intermediate low- and high-contrast acuity and 3-meter and near stereoscopic acuity were better with bifocal lenses. Near high- and low-contrast acuity were better with monovision. All subjective ratings, except near vision in poor lighting, were significantly greater with bifocal lenses. CONCLUSIONS: It is possible to refit successful monovision lens wearers with simultaneous vision bifocal lenses, and these lenses should be considered as an alternative method for the correction of presbyopia. In addition, subjective responses to bifocal lenses may not be reflective of visual function measurements.

Adult↗
PubMed1989

A longitudinal study of the changes in the static accommodation response.

The results are described of a 10-year study of the longitudinal changes in the static response of an individual subject during the approach to absolute presbyopia. The amplitude of accommodation declines linearly with age. A new finding is that the magnitude of the slope of the linear portion of the response/stimulus curve also reduces with age, as does the level of tonic accommodation.

Accommodation, Ocular↗
PubMed1990

Liquid crystal lens review.

Liquid crystal lenses are possibly the spectacle lenses of the future for presbyopic corrections. They present a variable refractive index which can be used to produce the necessary addition needed for presbyopia. The variability of the refractive index is due to the fact that these materials are optically anisotropic. This effect is obtained by the application of an electric or magnetic field through the liquid crystal layer. A review of the literature relating to the evolution, the preparation and the operation of these lenses is given. A discussion is also included of the practical problems and drawbacks, which at present limit their use, and possible solutions.

Eyeglasses↗
PubMed1993

Prescribing for presbyopes who use VDUs.

It has been widely assumed that VDU users position their paperwork closer than the screen to their eyes by an amount which may exceed their depth of field. The design and prescription of spectacles for the presbyopic VDU user must take these working distances into account. From theoretical considerations, the focal characteristics of occupational spectacles are matched to combinations of working distances. Measurement of these distances was carried out on a sample of 243 VDU users, 101 of whom were presbyopic and 53 nearing presbyopia. The results were analysed in terms of type of work and accommodative reserve, and compared with previous studies. Contrary to the views of several previous workers, it was found that paperwork did not tend to be positioned closer than the screen to the eyes. This finding was little affected by the type of VDU use or the accommodative reserve of the subject. Special occupational spectacle lens forms are thus not generally indicated for presbyopes at the VDU workstation.

Accommodation, Ocular↗
PubMed1969

The significance of the shape of the lens and capsular energy changes in accommodation.

1. A method for the estimation of the energy released by the anterior part of the lens capsule during accommodation is described. This includes(i) A determination of the pressure required to distend the capsule by a standard volume.(ii) The calculation from the photographed lens profiles of the degree of capsular contraction which occurs when the lens changes from the unaccommodated to the accommodated form.(iii) Capsular volume changes in vitro are then related to the surface area changes calculated for the lens in vivo.2. A correlation exists between the stored capsular energy per unit area or surface tension and the accommodation power of different species. The human lens capsule releases 1170 ergs/cm(2) while the more spherical lenses of the cat and rabbit release 520 and 485 ergs/cm(2) respectively for a 10% change in lens diameter. The amount of energy which can be stored depends on the degree of flatness of the lens and the volume of the anterior segment. The flatter the lens and the smaller the volume of the anterior segment, the greater the capsular surface tension.3. The anterior surface of the human lens remains ellipsoidal throughout life. The changes of accommodation which occur in presbyopia may therefore be related to the lens profiles at various ages. It is found that a coefficient obtained by dividing the anterior volume of the lens by the 5th power of the equatorial radius of the lens modifies the degree of accommodation for a given change of lens diameter.4. The loss of accommodation is proportional to the effective capsular surface energy until about the age of 45. The effective capsular surface energy can be defined as the energy which gives the same change in lens dioptric power per erg regardless of the lenticular profile changes which occur with age. It is obtained by multiplying capsular surface tension at a given age by a ratio. This is obtained by dividing the profile coefficient mentioned in paragraph 3 of the given lens, by the profile coefficient of the reference lens aged 15 (0.068). The effective surface energy of the entire lens falls from 110 ergs at the age of 15 to 50 ergs at 60. Assuming that ciliary power remains unaltered 55% of the loss of accommodation is accounted for solely by the fall in Young's Modulus of elasticity of the capsule and the changing shape of the lens with age.

Accommodation, Ocular↗
PubMed2002

High precision subsurface photodisruption in human sclera.

BACKGROUND AND OBJECTIVES: Femtosecond pulses can generate high precision subsurface photodisruption in transparent tissues, such as the cornea. We used femtosecond laser technology to demonstrate early proof of concept for high precision subsurface photodisruption in the translucent sclera. This technique may ultimately enable novel surgical procedures for the treatment of glaucoma and/or presbyopia. STUDY DESIGN/METHODS AND MATERIALS: Microjoule femtosecond pulses from two different sources, 1060 and 775 nm, were used to make subsurface incisions in human sclera in vitro. Scleral tissue was dehydrated to improve translucency at these wavelengths. The beam was focused to a 1.5 (775 nm) or 5 microm spot size (1060 nm) and scanned below the tissue surface at various depths to produce four incision patterns. RESULTS: Photodisruption on the backsurface of the sclera was achieved without damage to overlying tissue. Several types of intrascleral incisions were made, including transcleral channels and grooves for scleral implants. CONCLUSIONS: High precision, subsurface scleral photodisruption can be achieved in vitro for a variety of intrascleral incisions. Further studies are required to determine if this technique is applicable in vivo for actual surgical applications.

Fiber Optic Technology↗
PubMed1981

Human ocular aging and ambient temperature.

A survey of the literature on the incidence of the age of onset of presbyopia in various parts of the world reveals a great deal of variation. At first sight this appears to correlate with geographical latitude, but statistical and epidemiological evidence rules this out in favour of ambient temperature. Indirect evidence suggests that the crystalline lens is located sufficiently near to the surface of the body for this to be a likely explanation.

Adult↗
PubMed1996

Risk factors and ocular senescence.

The first part of this paper is devoted to a brief survey of novel aspects of ocular senescence which are shown to fit into the general, apparently genetic, non-pathological framework of senescence. This is followed by an analysis of recent work on presbyopia, the sight of the elderly, which is easily remedied by the provision of reading glasses and, incidentally, seems to be an example of growth rather than senescence. A consideration of graver consequences of senescence in the eye lens is presented next in a detailed analysis of cataracts. Age-related afflictions of the retina conclude the survey.

Aging↗
PubMed1981

An ergo-ophthalmological battery of tests to classify truck drivers.

16 healthy and ophthalmologically normal truck drivers are tested with a battery of tests according to the routine described in the following paper. This includes isopter perimetry, colour discrimination, recovery of sensitivity during dark adaptation and refraction at both far and near points, in order to record night myopia as well as night presbyopia. The ranges of individual variability are reported. As far as refraction is concerned, it seems of interest to stress the individual differences in a sort of "transient anisometropia" under incoming twilight.

Accidents, Traffic↗
PubMed2000

Psychological factors and sex differences in acceptance of monovision.

49 participants, adapted to using contact lenses, completed a battery of psychological tests to examine differences between persons who were successful in wearing monovision lenses for presbyopia and those who were unsuccessful. Although visual performance and requirements strongly affect participants' satisfaction with monovision lenses, personality characteristics and visual processing styles appear to in fluence the percentage of full-time wear. Of the participants, 41% (20 of 49) ultimately rejected monovision for a variety of both visual and psychological reasons. Sex differences were evidenced in the psychological variables correlated to monovision lens wear. Analysis indicated that men scoring as introverts rejected monovision while women with difficulty perceiving a visual pattern against visual background noise had difficulty adapting to monovision and exhibited shorter wearing times.

Accommodation, Ocular↗
PubMedDate not supplied

Ocular integrity after anterior ciliary sclerotomy and scleral ablation by the Er:YAG laser.

PURPOSE: To establish the risk of ocular rupture after proposed surgical reversal of presbyopia by anterior ciliary sclerotomy (ACS) or by the Er:YAG laser (HOYA Continuum, Tokyo, Japan). METHODS: A total of 45 pig eyes (15 control eyes) were examined. Fifteen eyes were placed into one of two study groups and another 15 eyes were used as controls. One group underwent scleral incisions with the use of a diamond knife, and the other group underwent Er:YAG laser scleral incisions. In both study groups, 8 radial incisions, 2 parallel cuts each at 4 quadrants, 2 mm apart, 4 mm long, and starting 2 mm away from the limbus, were made. A 3-kg steel weight was released from a measured height to the pig's eye, and ocular rupture energy (joules) was measured. RESULTS: The mean rupture energy was 26.0 J for control eyes, 15.7 J for the ACS eyes, and 12.2 J for the Er:YAG laser eyes. The ACS and the Er:YAG laser eyes ruptured at significantly lower energies (ACS, P < .001; Er:YAG, P < .001) than the control eyes. Comparison of the ACS group and the Er:YAG laser group showed no statistically significant difference (P = .052) in rupture energy. CONCLUSIONS: Scleral incisions by ACS and the Er:YAG laser significantly weakened ocular integrity compared with control eyes. Any patients undergoing ACS or Er:YAG laser scleral incision should be informed of the attendant potential risk after ocular trauma.

Animals↗
PubMedDate not supplied

Objective quality of vision in presbyopic and non-presbyopic patients after pseudoaccommodative advanced surface ablation.

PURPOSE: To analyze the objective quality of vision at 6 months postoperatively after pseudoaccommodative (presbyopic) advanced surface ablation (PASA). METHODS: The study comprised 62 eyes of 35 patients with 6-month follow-up that underwent primary or secondary treatments using PASA. Pre- and postoperative results of distance and near uncorrected visual acuity (UCVA), spherical aberration (coefficient of the Z12 Zernike polynomial), and the asphericity (Q) index were reviewed. The corresponding wavefront maps (total, low, and high order aberrations) and the corresponding point spread function and modulation transfer function (MTF) were also calculated. RESULTS: Our results show that PASA improves distance and near mean UCVA, increases negative spherical aberration and negative asphericity index, and improves the corresponding MTF. CONCLUSIONS: Pseudoaccommodative advanced surface ablation is a promising approach for the surgical correction of presbyopia with distance refractive error (myopia and hyperopia with or without astigmatism). This PASA technique could theoretically be used in non-presbyopic patients with refractive error or post cataract patients with monofocal intraocular lenses. The increase in negative spherical aberration and asphericity/eccentricity index seems to increase the depth of focus of the eye, improving the near vision and compensating the age-related lens changes. Rather than creating a multifocal cornea, PASA appears to create an improved aspheric (prolate) ablation profile.

Accommodation, Ocular↗
PubMed1985

Work with video display terminals among office employees. III. Ophthalmologic factors.

The present ophthalmologic study is the third part of a major epidemiologic health investigation on work with a video display terminal (VDT). An initial study showed that VDT operators replying to a questionnaire reported more eye discomfort than a reference group not employed in VDT work and that women reported more eye discomfort, musculoskeletal discomfort, headache, and skin disorders than men, irrespective of whether or not they were employed in VDT work. In the present study the ophthalmologic history of eye diseases and eye discomfort yielded a much lower percentage response for symptoms and discomfort than the questionnaire, and, just as with visual acuity and refraction, there was no difference between the exposed and reference groups or between the men and women. The exposed subjects were found to be overcorrected in terms of presbyopia addition in relation to work distance. As regards ocular examination findings, low frequency rates were noted for pathological lens opacities. Opacities of this kind were slightly more frequent among the VDT operators than among the referents, but the difference was not statistically significant. There were no other differences in the ocular findings of the exposed and reference groups.

Adult↗
PubMed1976

Headaches in relation to the eyes.

An analysis of patients presenting with headache shows that in very few cases is the headache related to refractive error. Similarly in presbyopia and hypermetropia headaches are infrequent. A significant proportion (up to 50%) of those patients presenting with a close relationship of headache to accommodation difficulty can be helped by glasses. It is postulated that ciliary muscle contraction per se is effortless and symptomless and that any headaches produced are due to associated contraction of the scalp muscles.

Adolescent↗
PubMed1976

Prevalence of undiagnosed eye/vision disorders in a VA hospital.

A study population of one hundred and one subjects, chosen according to recommended epidemiologic procedures to assure an accurate representation of the total Birmingham veteran population, were given complete optometric examinations. The primary criterion for inclusion in the study was a need for coming to the hospital on the interview day for any health problem other than visual or ocular. The results of the statistical analysis showed agreement between the Birmingham veteran population and the general population with regard to vision and ocular disorders. Presbyopia was found to be the most prevalent vision disorder, and fifty-four per cent of the study population needed either prescription lenses for the first time or a significant change in their present spectacles for maximum visual acuity. When this figure is projected nationally, fifty-four percent of the fourteen million outpatients treated last year in VA medical care facilities would represent 7,616,000 veterans in need of vision care services annually. In fact, since the sample average age was 46, and the average age for veterans nationally is 55, the figure for those with uncorrected vision defects may be even higher.

Adult↗
PubMed1999

Relationship between age and presbyopic addition using a sample of 3,645 examinations from a single private practice.

BACKGROUND: This study uses information collected in a private optometric practice to describe the relationship between age and the add power needed to correct presbyopia. METHODS: Computer-assisted data analysis with a database management program, Q&A, and Microsoft Excel was used to assess the relationship between age and presbyopic addition. Data collected from 3,645 examinations by one practitioner in a single private practice--over a period of approximately 23 years--were entered into the database. The patient base was primarily white and about equally divided between the sexes. The practitioner generally used the fused cross cylinder for the tentative presbyopic addition and refined this by patient preference and best visual acuity at near, all using a carefully determined near working distance. RESULTS: The presbyopic addition increased rapidly in patients from ages 40 to 50 years, the rate at age 40 being about 0.22 diopters per year and the average rate during the 40- to 50-year-old decade being about 0.12 diopters per year, or approximately 0.25 diopters every 2 years. After the patient reaches 50 years of age, the presbyopic addition increased more slowly, at the rate of approximately 0.03 diopters per year--or approximately 0.25 diopters in 8 years. CONCLUSIONS: Quantitative data taken from more than 3,600 refractions showed a nearly parabolic relationship between age and presbyopic addition from approximately the age of 40 to 75 years.

Adult↗