Trifocal intraocular lenses versus bifocal intraocular lenses after cataract extraction among participants with presbyopia.

BACKGROUND: Presbyopia occurs when the lens of the eyes loses its elasticity leading to loss of accommodation. The lens may also progress to develop cataract, affecting visual acuity and contrast sensitivity. One option of care for individuals with presbyopia and cataract is the use of multifocal or extended depth of focus intraocular lens (IOL) after cataract surgery. Although trifocal and bifocal IOLs are designed to restore three and two focal points respectively, trifocal lens may be preferable because it restores near, intermediate, and far vision, and may also provide a greater range of useful vision and allow for greater spectacle independence in individuals with presbyopia. OBJECTIVES: To assess the effectiveness and safety of implantation with trifocal versus bifocal IOLs during cataract surgery among participants with presbyopia. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2019, Issue 9); Ovid MEDLINE; Embase.com; PubMed; ClinicalTrials.gov; and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). We did not use any date or language restrictions in the electronic search for trials. We last searched the electronic databases on 26 September 2019. We searched the reference lists of the retrieved articles and the abstracts from the Annual Meeting of the Association for Research in Vision and Ophthalmology (ARVO) for the years 2005 to 2015. SELECTION CRITERIA: We included randomized controlled trials that compared trifocal and bifocal IOLs among participants 30 years or older with presbyopia undergoing cataract surgery. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methodology. MAIN RESULTS: We identified five studies conducted in Europe with a total of 175 participants. All five studies assessed uncorrected distance visual acuity (primary outcome of the review), while some also examined our secondary outcomes including uncorrected near, intermediate, and best-corrected distance visual acuity, as well as contrast sensitivity. Study characteristics All participants had bilateral cataracts with no pre-existing ocular pathologies or ocular surgery. Participants' mean age ranged from 58 to 64 years. Only one study reported on gender of participants, and they were mostly women. We assessed all the included studies as being at unclear risk of bias for most domains. Two studies received financial support from manufacturers of lenses evaluated in this review, and at least one author of another study reported receiving payments for delivering lectures with lens manufacturers. Findings All studies compared trifocal versus bifocal IOL implantation on visual acuity outcomes measured on a LogMAR scale. At one year, trifocal IOL showed no evidence of effect on uncorrected distance visual acuity (mean difference (MD) 0.00, 95% confidence interval (CI) -0.04 to 0.04; I2 = 0%; 2 studies, 107 participants; low-certainty evidence) and uncorrected near visual acuity (MD 0.01, 95% CI -0.04 to 0.06; I2 = 0%; 2 studies, 107 participants; low-certainty evidence). Trifocal IOL implantation may improve uncorrected intermediate visual acuity at one year (MD -0.16, 95% CI -0.22 to -0.10; I2= 0%; 2 studies, 107 participants; low-certainty evidence), but showed no evidence of effect on best-corrected distance visual acuity at one year (MD 0.00, 95% CI -0.03 to 0.04; I2= 0%; 2 studies, 107 participants; low-certainty evidence). No study reported on contrast sensitivity or quality of life at one-year follow-up. Data from one study at three months suggest that contrast sensitivity did not differ between groups under photopic conditions, but may be worse in the trifocal group in one of the four frequencies under mesopic conditions (MD -0.19, 95% CI -0.33 to -0.05; 1 study; I2 = 0%, 25 participants; low-certainty evidence). In two studies, the investigators observed that participants' satisfaction or spectacle independence may be higher in the trifocal group at six months, although another study found no evidence of a difference in participant satisfaction or spectacle independence between groups. Adverse events Adverse events reporting varied among studies. Two studies reported information on adverse events at one year. One study reported that participants showed no intraoperative or postoperative complications, while the other study reported that four eyes (11.4%) in the bifocal and three eyes (7.5%) in the trifocal group developed significant posterior capsular opacification requiring YAG capsulotomy. The certainty of the evidence was low. AUTHORS' CONCLUSIONS: There is low-certainty of evidence that compared to bifocal IOL, implantation of trifocal IOL may improve uncorrected intermediate visual acuity at one year. However, there is no evidence of a difference between trifocal and bifocal IOL for uncorrected distance visual acuity, uncorrected near visual acuity, and best-corrected visual acuity at one year. Future research should include the comparison of both trifocal IOL and specific bifocal IOLs that correct intermediate visual acuity to evaluate important outcomes such as contrast sensitivity and quality of life.

Objective Assessment of Ocular Surface Response to Contact Lens Wear in Presbyopic Contact Lens Wearers of Asian Descent.

INTRODUCTION: Contact lens wearers of Asian descent may be predisposed to experience microtrauma of the ocular surface as a result a thinner post-lens tear film and higher eyelid tension, and these effects would be anticipated to be most marked in an older population. The objective of this study was to quantify the mechanical effects of the study contact lenses on the ocular surface in a population of presbyopic contact lens wearers of Asian descent. METHODS: Twenty established presbyopic contact lens wearers (hydrogel n=5, none habitual wearers of etafilcon A lenses; silicone hydrogel n=15) of Asian descent were refitted with etafilcon A multifocal daily disposable contact lenses (1-DAY ACUVUE MOIST MULTIFOCAL) for a period of 1 month of daily lens wear. The habitual modalities of wear were 45% daily disposable and 55% planned replacement. Digital photographs of the upper lid margins, nasal and temporal conjunctiva, and superior cornea were taken after 6 hr of wear of the participants' habitual contact lenses, after 1 day without contact lens wear, and after 6 hr of wear of the study contact lenses at the end of the 1-month period. The photographs were masked according to study visit and the staining extent measured using proprietary software. RESULTS: Lid margin staining was significantly lower with the study contact lenses (2.0±1.0 mm) than with the participants' own contact lenses (3.2±3.0 mm) after 6 hr of wear, representing a mean staining decrease of 38% (P=0.010). Lid margin staining after 6 hr of wear of the study contact lenses was not different from that measured after 1 day without contact lenses (P=0.507). Limbal staining was also significantly less with the study contact lenses than with the participants' own contact lenses after 6 hr of wear (P=0.009). There was minimal upper corneal staining, and the degree was similar with the study and habitual lenses. CONCLUSIONS: Etafilcon A material, worn under a daily disposable modality, was shown to reduce upper lid margin and limbal staining in presbyopic contact lens wearers of Asian descent compared with the wearers' own contact lenses. Because of the high preponderance of dry eye amongst presbyopes, material selection is of importance and consideration should be given to the lens-ocular surface interaction.

Comparison of Extended Depth-of-Focus Prototype Contact Lenses With the 1-Day ACUVUE MOIST MULTIFOCAL After One Week of Wear.

OBJECTIVES: To compare visual performance of extended depth-of-focus (EDOF) prototypes with a new, center-near, commercial, multifocal contact lens. METHODS: Presbyopic participants (n=57) wore 1-Day ACUVUE MOIST MULTIFOCAL (1DAMM) and an EDOF prototype for one week in a double-masked, prospective, cross-over, randomized clinical trial. Manufacturers' guide was used to select the first pair of lens to be fit based on subjective distance refraction and near addition. After one week, high- and low-contrast visual acuities were measured at distance (6 m), intermediate (70 cm) and near (50 and 40 cm), and stereopsis at 40 cm. Subjective performance was assessed on a 1 to 10 numeric rating scale for vision clarity and lack of ghosting at distance, intermediate and near, vision stability, haloes at night time, overall vision satisfaction, and ocular comfort. Linear mixed models were used for analysis and the level of significance was set at 5%. RESULTS: 1DAMM was not significantly different from EDOF for high- or low-contrast visual acuity at any distance, or for stereopsis. Subjectively, EDOF was significantly better than 1DAMM for vision clarity at intermediate (P=0.033) and near (P<0.001), overall lack of ghosting (P=0.012), vision stability (P=0.004), and overall vision satisfaction (P=0.005). For all other subjective variables, there were no differences between EDOF and 1DAMM (P>0.05). CONCLUSIONS: EDOF prototype lenses offer improvements over the newly marketed 1DAMM lenses for several subjective variables.

Predicting Short-term Performance of Multifocal Contact Lenses.

OBJECTIVE: To investigate if initial multifocal contact lens (MFCL) performance predicts short-term dispensing performance. METHODS: 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. RESULTS: 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<0.001). Willingness to purchase remained the same at fitting and assessment in 68% of Px, whereas only 4% of Px converted to a positive willingness to purchase at assessment. The majority of acuity-based measures remained constant between fitting and assessment visits. CONCLUSION: Initial performance at fitting was not able to predict short-term performance of MFCL. Subjective measures peaked at fitting and declined thereafter whereas acuity-based measures remained constant. Utility of subjective rating tools may aid practitioners to gauge success of MFCL.

Intermediate addition multifocals provide safe stair ambulation with adequate 'short-term' reading.

PURPOSE: A recent randomised controlled trial indicated that providing long-term multifocal wearers with a pair of distance single-vision spectacles for use outside the home reduced falls risk in active older people. However, it also found that participants disliked continually switching between using two pairs of glasses and adherence to the intervention was poor. In this study we determined whether intermediate addition multifocals (which could be worn most of the time inside and outside the home and thus avoid continual switching) could provide similar gait safety on stairs to distance single vision spectacles whilst also providing adequate 'short-term' reading and near vision. METHODS: Fourteen healthy long-term multifocal wearers completed stair ascent and descent trials over a 3-step staircase wearing intermediate and full addition bifocals and progression-addition lenses (PALs) and single-vision distance spectacles. Gait safety/caution was assessed using foot clearance measurements (toe on ascent, heel on descent) over the step edges and ascent and descent duration. Binocular near visual acuity, critical print size and reading speed were measured using Bailey-Lovie near charts and MNRead charts at 40 cm. RESULTS: Gait safety/caution measures were worse with full addition bifocals and PALs compared to intermediate bifocals and PALs. The intermediate PALs provided similar gait ascent/descent measures to those with distance single-vision spectacles. The intermediate addition PALs also provided good reading ability: Near word acuity and MNRead critical print size were better with the intermediate addition PALs than with the single-vision lenses (p < 0.0001), with a mean near visual acuity of 0.24 ± 0.13 logMAR (~N5.5) which is satisfactory for most near vision tasks when performed for a short period of time. CONCLUSIONS: The better ability to 'spot read' with the intermediate addition PALs compared to single-vision spectacles suggests that elderly individuals might better comply with the use of intermediate addition PALs outside the home. A lack of difference in gait parameters for the intermediate addition PALs compared to distance single-vision spectacles suggests they could be usefully used to help prevent falls in older well-adapted full addition PAL wearers. A randomised controlled trial to investigate the usefulness of intermediate multifocals in preventing falls seems warranted.

Which ratio of areas improves vision quality in simultaneous focus optics?

PURPOSE: To evaluate the impact of the center optical zone diameter (COZD) of center-near bifocal optics on the through-focus subjective quality of vision. METHODS: Subjective image quality was assessed by 14 young, normally sighted subjects. Computed images of three high-contrast 20/50 letters were generated, across a range of object vergences from +2 diopters (D) to -4 D in 0.25-D steps. The center near optical zone addition power was +2.50 D, and the diameter of this center zone was varied in 10% steps to cover from 0% (single vision distance) to 90% of the 4.5-mm pupil diameter. Subjects rated image clarity of these computed images on a 0 to 5 scale, through a 3-mm pupil to limit the effect of their own aberrations. RESULTS: To quantify the efficiency of bifocal optics, we calculated the area under the through-focus subjective quality of vision curve. A criterion higher than 2 was judged to be an acceptable level of quality of vision, normalized by the naked eye condition. The average benefit of the optical profiles is highly subject dependent (i.e., from 0.8 to 1.9), potentially explaining why some subjects are not satisfied with simultaneous vision multifocal corrections. Averaged across subjects, the best benefit (i.e., 1.42) was obtained with a COZD covering 40% of the pupil area, whereas the 20, 30, and 50% profiles provide slightly lower benefit (i.e., ∼1.35). A COZD covering 20% of the pupil area equalized distance and near quality of vision. CONCLUSIONS: Quality of vision with bifocal optics is highly subject dependent. Peripheral rays do not seem to play an important role in the through-focus quality of vision, as the central pupil area is more heavily weighted in determining subjective image quality.

The vertical monitor position for presbyopic computer users with progressive lenses: how to reach clear vision and comfortable head posture.

When presbyopic employees are wearing general-purpose progressive lenses, they have clear vision only with a lower gaze inclination to the computer monitor, given the head assumes a comfortable inclination. Therefore, in the present intervention field study the monitor position was lowered, also with the aim to reduce musculoskeletal symptoms. A comparison group comprised users of lenses that do not restrict the field of clear vision. The lower monitor positions led the participants to lower their head inclination, which was linearly associated with a significant reduction in musculoskeletal symptoms. However, for progressive lenses a lower head inclination means a lower zone of clear vision, so that clear vision of the complete monitor was not achieved, rather the monitor should have been placed even lower. The procedures of this study may be useful for optimising the individual monitor position depending on the comfortable head and gaze inclination and the vertical zone of clear vision of progressive lenses. PRACTITIONER SUMMARY: For users of general-purpose progressive lenses, it is suggested that low monitor positions allow for clear vision at the monitor and for a physiologically favourable head inclination. Employees may improve their workplace using a flyer providing ergonomic-optometric information.

[Refraction after Implantation of Multifocal and Presbyopia-Correcting Intraocular Lenses]. / Richtiges Refraktionieren nach Implantation von Multifokal- und presbyopiekorrigierenden Intraokularlinsen.

Nowadays, further developments in the field of intraocular lenses offer a higher level of spectacle independence for our patients. As light gets scattered on different focal points a wider range of defocus is created. This greater defocus area makes it more difficult for us to determine the objective or subjective refraction. This contribution is concerned with the difficulties of measuring visual acuity in different intraocular lens designs and different measurement distances. Measuring refraction after implantation of a multifocal intraocular lens is a complex procedure and the experience of the examiner plays a crucial role. Retinoscopy, keratometry and the defocus curve are reliable methods for testing, while the auto refractometer, bichromatic testing and the cross-cylinder have limitations.

Presbyopia: a pilot investigation of the barriers and benefits of near visual acuity correction among a rural Filipino population.

BACKGROUND: Presbyopia is the age-related decline in accommodation that diminishes the ability of the eye to focus on near objects. Presbyopia is common and easy to correct; however, many communities lack access to basic eye care. The purpose of this project was to assess the burden of uncorrected presbyopia in a rural Filipino population and to pilot an intervention aimed at increasing access to reading glasses in the community. METHODS: Individuals above the age of 40 who presented to a health outreach in the Philippines were invited to undergo a near vision exam to detect the presence of functional presbyopia and be fitted with ready-made, single-vision glasses. The change in stereoacuity was used as a surrogate measure of functional improvement after near vision correction. A questionnaire was administered to assess this population's perceived barriers and benefits to correcting near vision. RESULTS: The average age of the participants was 57 ± 11 years, with 87.6% of participants having an uncorrected near visual acuity of <20/50. Reading glasses improved near vision to 20/40 or better in 77.7% of participants having near-vision impairment (uncorrected near visual acuity of <20/40). Over 75% of participants also showed improvement in stereoacuity. Cost, rather than availability, was perceived to be the greater barrier to the procurement of glasses, and 84% of participants reported that the glasses dispensed would greatly improve their ability to earn a living. CONCLUSIONS: Dispensing ready-made, single-vision glasses is a simple and cost-effective intervention to improve near vision and enhance depth perception. A greater understanding of the barriers and benefits to correcting near vision will inform the design and execution of a sustainable program to correct presbyopia in developing countries.

Developments in the correction of presbyopia I: spectacle and contact lenses.

PURPOSE: To outline the refractive problems associated with presbyopia and to review the basis and relative merits of currently-available methods for their correction, with detailed consideration of spectacle and contact lens approaches. CONTENTS: In the developed world, most of the present population will spend roughly half their lives as presbyopes. The well-known presbyopic changes with age in amplitude of accommodation and required near addition are briefly reviewed, together with the less widely acknowledged slow drifts that occur in distance refraction. The desirability of restoring to presbyopes clear vision for objects at any distance, ideally corresponding to vergences within the range of at least 0 to -5 D, in any viewing direction, is stressed. A general outline is given of possible corrective methods. Methods which satisfy the needs of a 50 year-old may not be suitable for the 80 year-old. Corrections may involve both fixed- and variable-focus lens systems, and surgical methods which modify the optics of the cornea, replace the crystalline lens with different fixed optics, or attempt to at least partially restore active accommodation. Some more recent methods of spectacle and contact lens correction are described in more detail. Particular attention is given to recent commercially-developed spectacles in which the corrective power can be varied actively by either mechanical (liquid-filled deformable lenses or Alvarez lenses) or electrical (liquid crystal lenses) means to allow objects at different distances to be seen clearly. Contact lens corrections show less progress and are still preferred only by a minority of older patients, most of whom are early presbyopes. SUMMARY: The rising proportion of presbyopes in the population, covering an age span of around 40 years, represents both a problem for those concerned with giving their patients the best vision possible at both far and near viewing distances and a commercial opportunity. Traditional single-vision distance and near, bifocal, and progressive spectacle lens solutions, together with contact lens modalities for presbyopic correction, are being challenged by a variety of new approaches. It remains to be seen whether the latter will receive wide acceptance in practice.

Presbyopia, spectacles use and spectacle correction coverage for near vision among cloth weaving communities in Prakasam district in South India.

PURPOSE: To assess the prevalence of presbyopia, spectacles use and spectacle correction coverage for near vision among weaving communities in Prakasam district in the South Indian state of Andhra Pradesh. METHODS: A population based cross sectional study was conducted among a population aged ≥40 years. Distance visual acuity was assessed at 6 m. Near vision was assessed using N notation charts at a fixed distance of 40 cm. Presbyopia was defined as binocular unaided near vision

Progressive addition lens measurement by point diffraction interferometry.

PURPOSE: Design a device for accurate measurements of local optical properties of progressive addition lenses (PALs). METHODS: A point diffraction interferometer has been adapted to measure local prescriptions of PALs. RESULTS: The most basic configuration of the interferometer for the measurement of PALs showed in this work presents high dynamic range and accuracy as well as the possibility of choosing the number and position of measurement points. Measurements are taken within a region of interest within a radius of about 0.4 to 1.5 mm. Different PAL designs are measured by the method proposed here and compared with results by a last generation commercial lens mapper. With the point diffraction interferometer we also compared several PAL designs in order to analyze their properties in the progression zone. CONCLUSIONS: The device is compact, robust, and fairly accurate, and the operational principle is very simple. By direct measurements it provides the local dioptric power, i.e., the second order wavefront properties, of the lens for selected regions of interest. The position and area can be chosen by the user. The only mobile part of the setup allows for the selection of the measurement points without any additional prismatic correction or movement of the PAL.

Objective measures of the effects of the "Read Without Glasses Method".

PURPOSE: The Read Without Glasses Method is a home-based vision training program designed to "avoid, eliminate, or reduce the need for bifocals" in presbyopic patients with 6 minutes of daily vision exercises. The purpose of this study was to objectively measure changes in accommodation and near unaided visual acuity (VA) in emmetropic presbyopes using this program. METHODS: Eight emmetropic presbyopes between 50 and 65 years of age participated in 2 pretreatment and 2 post-treatment visits. Primary outcome measures included near unaided VA (MNREAD acuity chart) and accommodative accuracy at near (Grand Seiko). Pupil size was measured at each visit during accommodative measures to assess the possibility that pupil size may have had an impact on near VA. Subjects were also queried about compliance and use of reading glasses after treatment. RESULTS: Repeated measures analysis of variance showed no significant change in unaided near VA pre- or post-treatment (p = 0.956). A statistically significant change in accommodation (0.176 D) was found at visit 3 (p = 0.0098) that did not persist at visit 4; however, this change was not clinically significant. Pupil size did not show significant change across all study visits. Survey results indicated that 87.5% of subjects reported that their near vision was slightly to significantly improved after the use of the program. CONCLUSIONS: The Read Without Glasses Method does not produce clinically or statistically significant changes in unaided near VA and fails to show clinically significant changes in accommodation at near in presbyopic emmetropes despite favorable subjective responses of participants.

Do reading additions improve reading in pre-presbyopes with low vision?

PURPOSE: This study compared three different methods of determining a reading addition and the possible improvement on reading performance in children and young adults with low vision. METHODS: Twenty-eight participants with low vision, aged 8 to 32 years, took part in the study. Reading additions were determined with (a) a modified Nott dynamic retinoscopy, (b) a subjective method, and (c) an age-based formula. Reading performance was assessed with MNREAD-style reading charts at 12.5 cm, with and without each reading addition in random order. Outcome measures were reading speed, critical print size, MNREAD threshold, and the area under the reading speed curve. RESULTS: For the whole group, there was no significant improvement in reading performance with any of the additions. When participants with normal accommodation at 12.5 cm were excluded, the area under the reading speed curve was significantly greater with all reading additions compared with no addition (p = 0.031, 0.028, and 0.028, respectively). Also, the reading acuity threshold was significantly better with all reading additions compared with no addition (p = 0.014, 0.030, and 0.036, respectively). Distance and near visual acuity, age, and contrast sensitivity did not predict improvement with a reading addition. All, but one, of the participants who showed a significant improvement in reading with an addition had reduced accommodation. CONCLUSIONS: A reading addition may improve reading performance for young people with low vision and should be considered as part of a low vision assessment, particularly when accommodation is reduced.

Strehl ratios characterizing optical elements designed for presbyopia compensation.

We present results of numerical analysis of the Strehl ratio characteristics for the light sword optical element (LSOE). For comparison there were analyzed other optical imaging elements proposed for compensation of presbyopia such as the bifocal lens, the trifocal lens, the stenopeic contact lens, and elements with extended depth of focus (EDOF), such as the logarithmic and quartic axicons. The simulations were based on a human eye's model being a simplified version of the Gullstrand model. The results obtained allow to state that the LSOE exhibits much more uniform characteristics of the Strehl ratio comparing with other known hitherto elements and therefore it could be a promising aid to compensate for the insufficient accommodation range of the human eye.

Imaging properties of the light sword optical element used as a contact lens in a presbyopic eye model.

The paper analyzes the imaging properties of the light sword optical element (LSOE) applied as a contact lens to the presbyopic human eye. We performed our studies with a human eye model based on the Gullstrand parameterization. In order to quantify the discussion concerning imaging with extended depth of focus, we introduced quantitative parameters characterizing output images of optotypes obtained in numerical simulations. The quality of the images formed by the LSOE were compared with those created by a presbyopic human eye, reading glasses and a quartic inverse axicon. Then we complemented the numerical results by an experiment where a 3D scene was imaged by means of the refractive LSOE correcting an artificial eye based on the Gullstrand model. According to performed simulations and experiments the LSOE exhibits abilities for presbyopia correction in a wide range of functional vision distances.

Clinical assessment of a customized free-form progressive add lens spectacle.

PURPOSE: To determine whether there are significant differences in standard clinical measures of vision, progressive addition lens (PAL)-specific vision tests, or subjective ratings and preferences between customized free-form and standard non-free-form PALs in an experienced wearing population. In addition, we aim to determine whether subjective or objective clinical outcomes depend on demographic, PAL usage, spectacle prescription, or frame fitting characteristics. METHODS: In a randomized, double-masked cross-over trial, 95 experienced wearers wore Zeiss Individual customized free-form PAL spectacles (test) and standard non-free-form PAL spectacles (control) for 1 week each. At dispensing and after 1 week of wear, subjects were tested for distance and near visual acuity under both high and low contrast; in addition, 30° off-axis visual acuity was measured using a novel apparatus, as was the horizontal extent of clear, undistorted vision at reading distance. Subjects also completed a set of questionnaires detailing their satisfaction levels, adaptation times, and preferences for test or control spectacles for different visual tasks. RESULTS: The test spectacles were preferred overall and for distance, midrange, transitional and active vision, and rated higher in overall satisfaction (p = 0.006). There were no clinically important differences between test and control spectacles in standard clinical vision assessments. In the PAL-specific assessments, however, the horizontal extent of clear vision at reading distance was significantly greater with the test spectacles (p = 0.004). CONCLUSIONS: There were statistically significant preferences for the optically customized free-form lenses over the non-free-form lenses. Subjects also reported a wider field of undistorted vision when looking through the reading zone of the test spectacles. Although standard clinical vision assessments are not sufficiently refined to detect important objective differences between the spectacle types, customization taking into account back vertex distance, segment height, pantoscopic tilt, and wrap angle can result in a superior subjective wearing experience for many PAL patients.

Stereoacuity with simultaneous vision multifocal contact lenses.

PURPOSE: To evaluate near stereoacuity (SA) with Focus Progressives and PureVision Multifocal simultaneous vision contact lenses. METHODS: In a cross-over study design, 20 presbyopic subjects were fitted with either the Focus Progressives or PureVision Multifocal lenses. After 1 month, SA was measured with the vectographic Titmus, Random dot stereotests, and the Howard-Dolman apparatus under photopic conditions (85 lux) at 40 cm. Binocular high-contrast visual acuity at distance and near was examined. Subjects were then refitted with the alternative correction and the procedure was repeated. RESULTS: Mean SA with the Focus Progressive was 21 +/- 7 sec arc, 54 +/- 17 sec arc, and 51 +/- 21 sec arc, with the Howard-Dolman, Titmus, and Random dot sterereotests, respectively. These values were 25 +/- 9 sec arc, 74 +/- 26 sec arc, and 82 +/- 26 sec arc with the PureVision Multifocal, respectively. SA was better with the Focus Progressives compared with the PureVision using the Howard-Dolman (4 sec arc of difference; p = 0.001), Titmus (2 sec arc of difference; p = 0.001), and Random dot (31 sec arc of difference; p < 0.001) tests. Binocular mean high-contrast distance visual acuity was similar for the Focus Progressives and PureVision Multifocal: -0.01 +/- 0.07 and +0.02 +/- 0.08 logMAR, respectively (p = 0.074). At near vision, these values were +0.01 +/- 0.07 and +0.06 +/- 0.06 logMAR, respectively, being statistically significant different (p = 0.004). CONCLUSIONS: Both the Focus Progressive and PureVision Multifocal contact lenses provided good visual acuity preserving stereopsis. Focus Progressives had slightly better near acuity and better SA than the Purevision Multifocal contact lenses. Differences found between the lens types may be related to asphericity, near addition of the contact lens, or even visual acuity differences between the two eyes that were not measured in this study but could conceivably have contributed to SA measure differences. SA measurement with a Howard-Dolman apparatus reveals better SA than vectographic tests.

Inherent ocular spherical aberration and multifocal contact lens optical performance.

PURPOSE: 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 olds and were further classified into five categories based on their magnitude of inherent SA. Two representative ametropic models of each category were corrected with four multifocal contact lens iterations. High-add designs were used to correct 55-year olds, whereas low-add designs served 45-year ones. The overall performances were gauged in terms of visual Strehl ratio and area under through-focus modulation transfer function. RESULTS: The root mean square error of higher order aberrations of the eye and correcting lens combination were significantly different (p < 0.05) within the five inherent SA models, for all pupils and accommodative states. Area under through-focus modulation transfer function at all three spatial frequencies tested was found to be significantly different (p < 0.05) within the five SA models. Visual Strehl ratio measures were also different but statistically insignificant. Eyes having the same refractive prescriptions but diverse levels of inherent SA perform differently even when corrected with identical multifocal designs, and the performance is dependent on pupil size and level of residual accommodation. Overall, the distinct performances within the five SA models were optically relevant for pupils ∼4 mm and greater. Among the designs investigated, the low-add multizone iteration demonstrated performance relatively independent of the inherent SA because of the favorable interactions of defocus with primary, secondary, and tertiary SA. CONCLUSIONS: These findings confirm that the coupling of ocular SA and correcting lens aberrations contributes to the multifocal functionality.

Phakic intraocular lenses: Recent advances and innovations. / Lentes intraoculares fáquicas: recientes avances e innovaciones.

Phakic intraocular lenses (pIOL) are recommended when counselling refractive surgery candidates presenting with high ametropia or ocular surface and/or corneal conditions that contraindicate corneal refractive surgery. This review aims to present the state-of-the-art regarding pIOL models currently available in Europe, addressing their newer indications and recent design innovations. These include, in the case of posterior chamber pIOLs, the addition of a central hole to improve aqueous humour circulation, the availability of larger optical zones, and multifocal optics for the compensation of presbyopia. The review also highlights their good safety and efficacy results, as well as the role of patient education to ensure adequate outcomes in the medium-long term. The indications of pIOLs in special situations, as well as bi-lensectomy, a procedure that most pIOL patients may eventually require as they age and develop cataracts, are also addressed.