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PubMed1975

Exophoria at near in presbyopia.

The exophoria at near working distances through a plus lens addition which exists in presbyopia was investigated in order to explain the paradoxical lack of asthenopic symptoms associated with this condition. Fixation disparity measurements indicate that the exophoria which is measured by the von Graefe technique does not exist under binocular conditions. Further analysis indicates that presbyopes may have unrestrained use of accommodative convergence.

Accommodation, Ocular↗

PubMed1988

Presbyopia in light of accommodation.

The "dual, indirect, active" mechanisms of accommodation proposed by Helmholtz is reviewed. New supporting evidence shows that the insertion of the ciliary muscle is onto the span fibrils of the zonule in the interciliary process regions of the ciliary body. Thus, the peripheral zonule is the elastic antagonist of a unified ciliary muscle. A biomechanical model illustrating accommodation is put forward that makes consistent and explicit the force and length changes that the six mechanical component elements undergo. The Hess-Gullstrand lenticular theory of presbyopia is compatible with this model.

Accommodation, Ocular↗

PubMed2003

Is binocular contrast sensitivity at distance compromised with multifocal soft contact lenses used to correct presbyopia?

PURPOSE: The purpose of this investigation was to determine whether new experimental multifocal optical designs incorporating diffractive/refractive optics for correction of presbyopia in a soft contact lens would compromise binocular contrast sensitivity at distance while achieving 20/20 binocular visual acuity at near. METHODS: Thirty presbyopic volunteers were fitted with Acuvue Bifocal soft lenses, two (FO1 and 3B1) experimental diffractive/refractive multifocal soft lenses separately and in combination as a pair and soft spherical lenses. Visual performance was evaluated via binocular contrast sensitivity and binocular distance high- and low-contrast visual acuity after 1 week of lens wear. RESULTS: The experimental lenses FO1 and the combination FO1/3B1 performed as well for binocular contrast sensitivity, binocular distance high-contrast visual acuity, and binocular distance low-contrast visual acuity as the habitual presbyopic correction and the spherical soft distance correction. A strong correlation (r = 0.73 and 0.53, respectively) was found between binocular contrast sensitivity and binocular distance low-contrast visual acuity with experimental FO1 and FO1/3B1 lenses. However, the correlation (r = 0.37 and 0.60, respectively) between binocular contrast sensitivity and binocular distance high- and low-contrast visual acuity with FO1 was weaker than that with the combination FO1/3B1 lenses. Subjective responses support the objective data. DISCUSSION: The data show that experimental FO1 lens and the experimental combination of the FO1/3B1 lenses can be prescribed to not compromise distance binocular contrast sensitivity.

Adult↗

PubMed2006

Comparison of multifocal and monovision soft contact lens corrections in patients with low-astigmatic presbyopia.

PURPOSE: The purpose of this study was to assess visual performance and patient satisfaction with two presbyopic soft contact lens modalities. METHODS: A crossover study of 38 patients with presbyopia was conducted. Patients were randomized first into either multifocal (Bausch & Lomb SofLens Multifocal) or monovision (SofLens 59) for 1 month. Visual performance was measured with high- and low-contrast visual acuity at distance and near and near stereoacuity. Patients' satisfaction was measured by the National Eye Institute Refractive Error Quality of Life Instrument questionnaire and by recording the patient's final lens preference. RESULTS: Patients maintained at least 20/20 binocular vision with both multifocal (MF) and monovision (MV) contact lenses under high-contrast conditions at distance and near. Under low-contrast conditions, patients lost less than a line of vision from the best spectacle correction to either multifocal or monovision contact lens correction at distance (pMF = 0.001, pMV = 0.006). Under low-contrast conditions at near, multifocal wearers lost five to six letters and monovision wearers lost two letters of vision (pMF < 0.001, pMV = 0.03, pMF/MV = 0.005). The average stereoacuity decreased by 79 s arc with monovision vs. multifocal contact lenses (p = 0.002). On the NEI-RQL, patients reported worse clarity of vision (pMF = 0.01, pMV < 0.001), more symptoms (pMF = 0.09, pMV = 0.01), and an improvement in their appearance with contact lens wear (pMF < 0.001, pMV < 0.001). Seventy-six percent of patients reported that they preferred multifocal contact lenses, and 24% preferred monovision contact lenses (p = 0.001). CONCLUSION: The majority of our patients preferred multifocals to monovision, most likely because the Bausch & Lomb SofLens Multifocal provides excellent visual acuity without compromising stereoacuity to the same degree as monovision.

Adult↗

PubMed1989

Presbyopia correction and the accommodation in reserve.

One method of determining the additional correction for presbyopia suggests leaving a percentage of the amplitude of accommodation in reserve. The rationale for this assumption seems logical because using all of the available accommodation is not sustainable without discomfort. However there is no empirical evidence indicating what percentage of the amplitude of accommodation should actually be left in reserve. Common figures adopted have been one-half and one-third. In this investigation the percentage of accommodation used is deduced mathematically after having determined the following: 1. The 'add' by the direct subjective clinical method. 2. Measured the amplitude of accommodation. 3. Measured the reading distance in 305 presbyopes ranging from 40 to 83 years of age. The results showed a small decline in the amplitude of accommodation up to the age of 52, after which age the measurements were scattered about a steady level. This finding suggests that after the age of 52 the results are based on the depth-of-focus of the eye. Females had slightly greater accommodation than males of the same age. The power of the add was significantly correlated to the age of the subject. The mean percentage of accommodation used for the 305 subjects was found to be 50.7%, thus confirming the rule of leaving half of the accommodation in reserve, although there were large variations: there were differences between males and females and with age the percentage of measured accommodation used, after having determined the correct add, diminished. Similarly the percentage of accommodation also decreased for shorter reading distances.

Accommodation, Ocular↗

PubMed1989

Contrast sensitivity with contact lens corrections for presbyopia.

We measured contrast sensitivity at three distances (330 mm, 660 mm and 4 m) with six contact lens and two multifocal spectacle corrections for presbyopia. The two spectacle corrections were D-segment bifocals and trifocals and the contact lens corrections were distance contact lens with lookover spectacles, soft progressive bifocals, soft concentric bifocals, monovision, modified monovision, and hard crescent segment bifocals. The spectacle corrections in general gave better results for the contrast sensitivity function (CSF), than did the contact lens corrections. Distance contact lenses with lookover spectacles performed best of the contact lens corrections used. However, the differences in CSF between the various contact lens corrections were small and not statistically significant.

Adolescent↗

PubMed1998

Zonal photorefractive keratectomy for presbyopia.

PURPOSE: We performed zonal excimer laser photorefractive keratectomy in three eyes of three presbyopic patients using a specially designed mask, with a minimum follow-up of 24-months. METHODS: Two females (ages 59 and 48) and one male (age 55) were included in the study. The procedure was performed with a mask designed by one of the authors (GMN), applied to the Aesculap-Meditec Mel 60 excimer laser. The mask consists of a mobile diaphragm formed by two blunt blades. The aim in all the eyes was a presbyopic correction of 3.00 D. RESULTS: After an initial regression of 1.00 D, the presbyopic correction remained stable during the 36-month follow-up. The patients read at least J3 at normal reading distance without correction. Since the ablated zone was only about 15% of the total area of a 3.0 mm pupil, all three patients were also able to read with their preoperative presbyopic correction (using the untreated 85% of the pupillary area). CONCLUSION: Although only three eyes were treated with the zonal presbyopia mask presented here, the visual and refractive outcome appears promising in view of the relatively long follow-up time.

Contrast Sensitivity↗

PubMedDate not supplied

Pseudo-accommodative cornea: a new concept for correction of presbyopia.

PURPOSE: Efficacy, predictability, stability, and safety of multifocal ablation with a peripheral near zone for correction of myopia, hyperopia, and presbyopia was assessed. METHODS: We performed a retrospective study of 83 hyperopic eyes and 77 myopic eyes. Baseline mean spherical equivalent refraction in the hyperopia group was +1.54 +/- 0.90 D (range 0 to +4.00 D) and in the myopia group, -4.31 +/- 2.62 D (range -12.00 to -0.25 D). Mean near addition was 2.40 D in the hyperopia group and 1.75 D in the myopia group. All eyes had multifocal laser in situ keratomileusis (LASIK) with a peripheral near zone, using a Nidek EC-5000 excimer laser. Pseudoaccommodative cornea (PAC) software version 6T was used to calculate the multistep ablation profile. RESULTS: Three months after surgery, 80 eyes (96.4%) of the hyperopia group and 75 eyes (97.4%) of the myopia group were examined. Postoperative mean spherical equivalent refraction was -0.19 +/- 0.58 D (range -1.75 to +1.00 D) in the hyperopia group and -0.50 +/- 0.75 D (range -2.50 to -0.75 D) in the myopia group. Fifty-eight eyes (72.5%) of the hyperopia group and 50 eyes (66.7%) of the myopia group were within +/-0.50 D of emmetropia. One percent of eyes in the hyperopia group and no eyes in the myopia group lost 2 or more lines of BSCVA; 5% of eyes in the hyperopia group and 12% eyes in the myopia group gained 2 or more lines of BSCVA. Mean near addition was 0.11 D in the hyperopia group and 0.07 in the myopia group. Binocular unaided near visual acuity was J3 or better in all eyes of both groups and J1 or better in 35% eyes in the hyperopia group and 41% of eyes in the myopia group. CONCLUSION: Multistep multifocal ablation with a peripheral near zone using the Nidek EC-5000 excimer laser and PAC software version 6T was effective, predictable, stable, and relatively safe over a period of 3 months.

Accommodation, Ocular↗

PubMed2006

Correction of presbyopia by technovision central multifocal LASIK (presbyLASIK).

PURPOSE: To investigate central multifocal presbyLASIK based on the creation of a central hyperpositive area. METHODS: Twenty-five patients (50 eyes) underwent presbyLASlK in an open-label, prospective, non-comparative pilot study. Mean patient age was 58 years (range: 51 to 68 years), mean preoperative spherical equivalent refraction was +1.6 +/- 0.63 diopters (D) (range: +0.50 to +3.00 D), and mean spectacle near addition was +2.27 +/- 0.37 D (range: +1.75 to +3.00 D). The ablation pattern was performed with proprietary software from Technovision using an H. Eye Tech. excimer laser platform. RESULTS: Mean postoperative spherical equivalent refraction was -0.37 +/- 0.55 D (range: -1.50 to + 1.00 D) and mean spectacle near addition was +1.72 +/- 0.34 D (range: +1.25 to +2.25 D). After 6 months, 16 (64%) patients achieved a distance uncorrected visual acuity (UCVA) of > or = 20/20 and 18 (72%) patients achieved a near UCVA of > or = 20/40. Seven (28%) patients lost a maximum of 2 lines of best spectacle-corrected visual acuity (BSCVA). The safety index for distance was 0.98 binocular and for near was 0.99 binocular. After 6 months, no significant change was noted in contrast sensitivity at 1.5 cycles/degree. A significant mean reduction was found at spatial frequencies of 3, 6, 12, and 18 cycles/degree (P<.001). There was a significant change in corneal aberrations after surgery. The coefficients for coma increased and the coefficients for spherical aberrations decreased. A significant decrease was noted in point spread function values (P=.0018). CONCLUSIONS: Central presbyLASIK may be used to provide improvement in functional near vision in patients with presbyopia associated with low and moderate hyperopia. However, factors involved in the loss of BSCVA in some cases and loss in vision quality should be further clarified prior to its general use.

Adult↗

PubMed1999

[Prismatic treatment for heterophoric decompensation after onset of presbyopia].

This study presents the results of the prescription of small prisms in horizontally (N = 11) and vertically (N = 5) heterophoric patients after the onset of presbyopia. There was a high incidence of diplopia (69%) at an age where fusionnal adaptation capacities are limited. Prismatic treatment released the diplopia and asthenopic complaints in 100% of the cases. The prisms were easily included in prescriptions for progressive lenses in half of the cases. Their strength was eventually decreased in 12.5% of the cases, and they were totally eliminated in 12.5%. The prescription had to be increased in only one case. The mean follow-up was 2.8 years (with a range from 1 to 7.5 years).

Adaptation, Physiological↗

PubMedDate not supplied

[Characteristics of correction of myopia by photorefractive keratectomy in patients with presbyopia].

Photorefraction keratectomy was performed with a Nidek EC-5000 excimer laser in 29 patients (58 eyes) with slight and medium myopia aged 40-60 years. After 12 months the mean visual acuity in the leading eye without correction was 0.82 +/- 0.12 in patients aged 40-50 (group 1) and 0.76 +/- 0.11 in those aged 51-60 years (group 2). The mean refraction of the leading eye in group 1 was -0.97 +/- 0.02 diopters and in group 2 0.72 +/- 0.04 diopters. In group 1 the resultant undercorrection was -1.6 +/- 0.4 diopters (107% of planned undercorrection) and in group 2 -1.8 +/- 0.4 diopters (72% of planned undercorrection). The proposed method effectively corrects slight and medium myopia in patients of presbyopia age. 82% patients were satisfied with the results of treatment: 67% of them did not need eyeglasses for reading and 54% could drive a car without eyeglasses.

Adult↗

PubMedDate not supplied

[Bifocal contact lenses as a correction method in presbyopia].

A study aimed at assessing the efficiency of presbyopia correction by bifocal contact lenses (BCL) was undertaken; it envisaged a comprehensive evaluation of subjective data provided by patients and measurements of a number of functional parameters of the visual quality for far and near, including mono- and binocular measurements with BCL of different constructions versus a maximal sphero-cylindrical spectacle correction for far and for near. Soft Acuvue Bifocal BCL as well as soft and rigid BCL manufactured in the optical-and-mechanical laboratory of the Research Institute for Eye Disease of the Russian Academy of Medical Sciences and Russian-made and imported bifocal soft and rigid lenses, respectively, were made use of in the study. A reduced contrast sensitivity (mainly in high frequencies) to 7% with Russian-made BCL, to 12.5% with Acuvue Bifocal BCL, to 8.7% with monofocal BCL and to 13.4% with the "mono-vision" system was registered. A decreased visual working ability to 13% with soft bifocal Russian-made BCL, to 17.3% with Acuvue Bifocal BCL and to 20.7% with the "mono-vision" system was detected versus the spectacle correction. A reduction by 25% was noted in the stereoscopic vision indices with the "mono-vision" system. A study of sensitivity to dazzling did not show any statistically reliable differences between various correction types.

Adult↗

PubMed2004

Massive increase in the stiffness of the human lens nucleus with age: the basis for presbyopia?

PURPOSE: To determine the stiffness of different regions of human lenses as a function of age, and to correlate the biophysical measurements in the lens center with nuclear water content. METHODS: A custom made probe fitted to a dynamic mechanical analyzer was employed to measure stiffness values at 1 mm increments across equatorial sections of individual human lenses. Thermogravimetric analysis was used to determine the percentage water content in the nuclei of human lenses. RESULTS: There was a pronounced increase in lens stiffness over the age range from 14 to 78. In the nucleus, stiffness values varied almost 1,000 fold over this age range, with the largest change observed in lenses between the ages of 20 to 60. Nuclear stiffness values increased on average by a factor of 450. By contrast, in the cortex the average increase in stiffness was approximately 20 fold over this same time period. In lenses younger than age 30, the nucleus was found to be softer than the cortex. This was true for all six lenses examined. In contrast all lenses older than 30 were characterized by having nuclear values higher than those of the cortex. In lenses over the age of 50, the lens nucleus was typically an order of magnitude more rigid than that of the cortex. The crossover age, when the cortical and nuclear stiffness values were similar, was in the 30s. There was no significant change in the water content of the human lens nucleus from age 13 to age 82. CONCLUSIONS: There is a marked increase in the stiffness of the human lens with age. This is most pronounced in the nucleus. Since in vivo data indicate that the nucleus must change shape significantly during accommodation, it is highly likely that these measured changes in physical properties will markedly diminish the ability of the lens to accommodate, and thus may be a major contributing factor to presbyopia. Since there was no measurable difference in the water contents of the nuclear regions of the lenses, this marked increase in stiffness is not due to compaction of the lens nucleus.

Adolescent↗

PubMed2006

[The use of accommodative lenses for surgical correction of the presbyopia using the Prelex method].

The authors refer about their experience with the surgical correction of the presbyopia by means of the Prelex (presbyopic lens exchange) method. Patients, who underwent this type of refractive surgery procedure to decrease their dependency on glasses correction for far as well as for near vision (12 patients, 23 eyes) and 1 young female patient (2 eyes) with juvenile cataract and high hyperopia, were included in the study. The average age at the time of the surgery was 51.0 +/- 5.5 years (range, 19-77 years). The average follow up period of the whole group of patients is 9.8 months (range, 1-13 months). Depending on the type of the lens implanted, the group was divided into subgroup A with the accommodative lens 1 CU produced by Human Optics Company implanted, and subgroup B with the accommodative lens Kellan TetraFlex KH 3500 produced by LensTec Company implanted. The subgroup A consists of 8 patients (15 eyes) with the average preoperative refractive error +2.35 +/- 3.45 diopters. The average uncorrected visual acuity of this group was 0.24 +/- 0.18, and the average best-corrected visual acuity was 0.77 +/- 0.22 at the time before the surgery. The average glasses correction for near was +4.1 dioptres, and the uncorrected vision for near was Jaeger's table Nr. (J) 13. The B subgroup consists of 5 patients (10 eyes). The average preoperative refractive error was +2.23 +/- 0.93 diopters. The average value of the uncorrected visual acuity before the surgery was 0.43 +/- 0.28, and the average corrected visual acuity was 0.82 +/- 0.25. The average value of the glasses correction for near was +5.25 and uncorrected vision for near J 13. The final average postoperative error at the time of the last visit was in the A subgroup +0.06 +/- 1.17 dioptres. The average uncorrected visual acuity was 0.69 +/- 0.24, and the average best-corrected visual acuity 0.96 +/- 0.12. The average vision of the patients of this subgroup for near was J 3. In the B subgroup we found at the last visit the average final value of the postoperative refractive error -0.2 +/- 0.72 dioptres. The average uncorrected visual acuity 0.57 +/- 0.22 and the average corrected visual acuity 0.95 +/- 0.12. Average uncorrected vision for near was J 5. We did not notice any serious per- or postoperative complication of this procedure.

Accommodation, Ocular↗

PubMed2005

[Advances on surgeries to correct presbyopia].

Surgeries to correct presbyopia are in its initial stage, Conductive Keratoplasty and LASIK multifocal ablation patterns are newly emerging methods. Multifocal IOL or Accommodative IOL provides new method to compensate accommodation of presbyopes, studies on scleral surgeries to restore accommodation are also in progress.

Adult↗

PubMed1991

Induced hyperphoria in anisometropic presbyopia.

Anisometropia occurring either as a result of physiological or acquired etiologies may present a challenge to the optometrist if the patient is presbyopic. Fortunately, many patients with anisometropic presbyopia are able to adapt to near induced hyperphoria. There are, however, several options available for the optical management of symptomatic patients with near induced hyperphoria. These include: displacement of the distance optical centers, setting the bifocal segment higher than usual, using a combination of these two, dissimilar bifocal segments, slab-off prism and contact lenses. This paper reviews clinical considerations as well as the available spectacle management options.

Adaptation, Ocular↗

PubMed1990

Presbyopia and the dentist: the effect of age on clinical vision.

Vision is extremely important in dentistry where many clinical tasks requiring fine discrimination are performed. Presbyopia, an inability to focus sharply on near objects, affects all dentists in the later years of their practising lives and may have adverse effects on the practice of dentistry. This study examined the visual acuity of 172 practising dentists using a reduced Snellen chart imaged at 25 cm and 33 cm. Twenty-seven per cent failed the near vision test, having acuity of less than 6/9 at 25 cm, while 18 per cent had acuity of less than 6/7.5 at 33 cm; 96 per cent of those who failed at 25 cm and 93.5 per cent of those who failed at 35 cm were 45 years of age or more. Working distance (operating distance) was found to be significantly greater in dentists over the age of 45 than in a group of undergraduate dental students. No statistically significant relationship between visual acuity and working distance could be demonstrated. Regular examinations by qualified personnel are essential for dentists who should have their eyes checked every 2 years after the age of 40. Dentists should discuss their specific requirements for the practice of dentistry with their eye-care specialist. A suggested minimum standard of visual acuity for practising dentists is 6/7.5 at 33 cm.

Adult↗

PubMed1989

The path to presbyopia: straight or crooked?

The non-linear trends in the mean amplitude of accommodation with age that are observed in transverse studies as presbyopia is approached can be explained in terms of the summated effect of many individual linear trends. Increases in the near addition that may be required by patients after their early fifties are probably associated with an age-dependent decrease in acuity, which necessitates a closer working distance to increase angular subtense, rather than with any continuing decline in accommodation.

Accommodation, Ocular↗