Visual Comparison of Multifocal Contact Lens to Monovision

Gaze and behavioural metrics in the refractive correction of presbyopia

PURPOSE

To investigate gaze and behavioural metrics at different viewing distances with multifocal contact lenses (MFCLs), single vision contact lenses (SVCLs) and progressive addition lenses (PALs).

METHODS

Fifteen presbyopic contact lens wearers participated over five separate study visits. At each visit, participants were randomly assigned to wear one of five refractive corrections: habitual PAL spectacles, delefilcon A (Alcon Inc.) MFCLs and three separate pairs of delefilcon A single vision lenses worn as distance, intermediate and near corrections. Participants wore a Pupil Core headset to record eye and head movements while performing three visual tasks: reading, visual search and scene observation. Data were investigated using linear regression and post-hoc testing. Parameters of interest included gaze (fixation duration, head movement) and behavioural (reading speed, reading accuracy, visual search time) metrics.

RESULTS

Reading speed in SVCLs was significantly faster than in MFCLs and PAL spectacles (F = 16.3, p < 0.0001). Refractive correction worn did not influence visual search times (F = 0.16, p = 0.85). Fixation duration was significantly affected by the type of visual task (F = 60.2, p < 0.001), and an interaction effect was observed between viewing distance and refractive correction (F = 4.3, p = 0.002). There was significantly more horizontal and vertical head movement (F = 3.2, p = 0.01 and F = 3.3, p = 0.01, respectively) during visual search tasks when wearing PAL spectacles compared to SVCLs or MFCLs.

CONCLUSION

This work showed that the type of refractive correction affects behavioural metrics such as reading speed and gaze behaviour by affecting horizontal and vertical head movements. The findings of this study suggest that under certain conditions, wearers of MFCLs make fewer head movements compared to PAL spectacles. Gaze behaviour metrics offer a new approach to compare and understand contact lens and spectacle performance, with potential applications including peripheral optical designs for myopia management.

BCLA CLEAR Presbyopia: Evaluation and diagnosis

It is important to be able to measure the range of clear focus in clinical practice to advise on presbyopia correction techniques and to optimise the correction power. Both subjective and objective techniques are necessary: subjective techniques (such as patient reported outcome questionnaires and defocus curves) assess the impact of presbyopia on a patient and how the combination of residual objective accommodation and their natural DoF work for them; objective techniques (such as autorefraction, corneal topography and lens imaging) allow the clinician to understand how well a technique is working optically and whether it is the right choice or how adjustments can be made to optimise performance. Techniques to assess visual performance and adverse effects must be carefully conducted to gain a reliable end-point, considering the target size, contrast and illumination. Objective techniques are generally more reliable, can help to explain unexpected subjective results and imaging can be a powerful communication tool with patients. A clear diagnosis, excluding factors such as binocular vision issues or digital eye strain that can also cause similar symptoms, is critical for the patient to understand and adapt to presbyopia. Some corrective options are more permanent, such as implanted inlays / intraocular lenses or laser refractive surgery, so the optics can be trialled with contact lenses in advance (including differences between the eyes) to better communicate with the patient how the optics will work for them so they can make an informed choice.

Efficacy of a new refractive multifocal contact lens for presbyopia

This prospective single-arm study aimed to evaluate the clinical efficacy and safety of a refractive multifocal contact lens for the correction of presbyopia in 22 patients. The participants underwent clinical examinations before and 1 week after wearing a refractive multifocal contact lens (OptaCon ZOOM). The primary endpoints were the corrected distance visual acuity (CDVA) and distance-corrected near visual acuity (DCNVA). Defocus curve, contrast sensitivity, and ocular surface disease index (OSDI) were analyzed. A slit-lamp examination was performed for safety analysis. Contact lens comfort and patient satisfaction were assessed using a questionnaire. No significant difference in CDVA was observed before and 1 week after refractive multifocal contact lens use (p = 0.127), whereas DCNVA was significantly improved after 1 week (p < 0.001). The contrast sensitivity was not significantly affected at any spatial frequency under mesopic or photopic conditions. OSDI was significantly increased (p = 0.023). The patient-reported satisfaction scores were 96.2, 91.9, and 85.0 out of 100 at far, intermediate, and near distances, respectively. No significant adverse events were observed. Refractive multifocal contact lenses improved near vision while maintaining distance vision in presbyopic patients, without compromising contrast sensitivity. The study results suggest that OptaCon ZOOM can be considered safe and effective for the correction of presbyopia.

BCLA CLEAR Presbyopia: Management with contact lenses and spectacles

This paper seeks to outline the history, market situation, clinical management and product performance related to the correction of presbyopia with both contact lenses and spectacles. The history of the development of various optical forms of presbyopic correction are reviewed, and an overview is presented of the current market status of contact lenses and spectacles. Clinical considerations in the fitting and aftercare of presbyopic contact lens and spectacle lens wearers are presented, with general recommendations for best practice. Current options for contact lens correction of presbyopia include soft simultaneous, rigid translating and rigid simultaneous designs, in addition to monovision. Spectacle options include single vision lenses, bifocal lenses and a range of progressive addition lenses. The comparative performance of both contact lens and spectacle lens options is presented. With a significant proportion of the global population now being presbyopic, this overview is particularly timely and is designed to act as a guide for researchers, industry and eyecare practitioners alike.

2022 Glenn A. Fry Award lecture: Enhancing clinical assessment for improved ophthalmic management

ABSTRACT

Detailed clinical assessment is critical to allow sensitive evaluation of the eye and its management. As technology advances, these assessment techniques can be adapted and refined to improve the detection of pathological changes of ocular tissue and their impact on visual function. Enhancements in optical medical devices including spectacle, contact, and intraocular lenses have allowed for a better understanding of the mechanism and amelioration of presbyopia and myopia control. Advancements in imaging technology have enabled improved quantification of the tear film and ocular surface, informing diagnosis and treatment strategies. Miniaturized electronics, large processing power, and in-built sensors in smartphones and tablets capacitate more portable assessment tools for clinicians, facilitate self-monitoring and treatment compliance, and aid communication with patients. This article gives an overview of how technology has been used in many areas of eye care to improve assessments and treatment and provides a snapshot of some of my studies validating and using technology to inform better evidence-based patient management.

Visual discomfort and contact lens wear: A review

The purpose of this manuscript is to describe how vision influences contact lens discomfort and review the evidence supporting the hypothesis that contact lens discomfort can be caused by vision and vision-related disorders. Contact lens discomfort is a misunderstood and difficult to manage clinical condition. Most treatments and strategies aimed at alleviating discomfort focus on optimizing the contact lens fit and its relationship with the ocular surface, but these strategies commonly fail at relieving discomfort symptoms. Many vision and vision-related disorders share symptoms with those reported by uncomfortable contact lens wearers. This paper will review evidence and literature that describes how these vision and vision-related disorders may influence comfort in contact lens wearers. Acknowledging how vision influences contact lens discomfort will improve future research intended to better understand the condition, allow for more effective clinical management, and reduce rates of discontinuation.

Multifocal versus modified monovision corrections: A non-dispensing comparison of visual assessment in presbyopic neophytes

Purpose

To compare the visual performance of two simultaneous-vision soft multifocal contact lenses and to compare multifocal contact lens and its modified monovision counterpart in presbyopic neophytes.

Methods

A double-masked, prospective, comparative study was conducted on 19 participants fitted with soft PureVision2 multifocal (PVMF) and clariti multifocal (CMF) lenses in random order. High- and low-contrast distance visual acuity, near visual acuity, stereopsis, contrast sensitivity, and glare acuity were measured. The measurements were conducted using multifocal and modified monovision design with one brand and then repeated with another brand of lens.

Results

High-contrast distance visual acuity showed a significant difference between CMF (0.00 [-0.10-0.04]) and PureVision2 modified monovision (PVMMV; -0.10 [-0.14-0.00]) correction (P = 0.003) and also between CMF and clariti modified monovision (CMMV; -0.10 [-0.20-0.00]) correction (P = 0.002). Both modified monovision lenses outperformed CMF. The current study did not show any statistically significant difference between contact lens corrections for low-contrast visual acuity, near visual acuity, and contrast sensitivity (P > 0.01). Stereopsis at near distance was significantly lower with both modified monovision (PVMMV: 70 [50-85]; P = 0.007, CMMV: 70 [70-100]; P = 0.006) and with CMF (50 [40-70]; P = 0.005) when compared to spectacles (50 [30-70]). Glare acuity was significantly lower with multifocal (PVMF: 0.46 [0.40-0.50]; P = 0.001, CMF: 0.40 [0.40-0.46]; P = 0.007) compared with spectacles (0.40 [0.30-0.40]), but no significant difference was noted between the multifocal contact lenses (P = 0.033).

Conclusion

Modified monovision provided superior high-contrast vision compared to multifocal correction. Multifocal corrections performed better for stereopsis when compared to modified monovision. In parameters like low-contrast visual acuity, near acuity, and contrast sensitivity, both the corrections performed similarly. Both multifocal designs showed comparable visual performances.

Comparison of visual performance between extended depth of focus contact lens and single-vision contact lens in eyes with monofocal intraocular lens

PURPOSE

To assess the visual performance of extended depth of focus (EDF) contact lenses (CL) in eyes that had undergone monofocal intraocular lens (IOL) implantation, and compare that between EDF and single-vision (SV) contact lenses.

STUDY DESIGN

Prospective, randomized, crossover study METHODS: Seventeen patients implanted with monofocal IOLs were enrolled. The study was conducted using 1dayPure EDOF as a test CL and 1dayPure moisture (both SEED Co., Ltd.) as a control CL. Binocular visual acuity from far to near distances, photopic and mesopic contrast sensitivity (with and without glare), and stereopsis were evaluated after wearing the two kinds of CLs in random order. The obtained results were compared between the EDF and SV CLs.

RESULTS

Binocular visual acuity at 0.3, 0.4, 0.7, 1, and 5 m was 0.24 ± 0.12, 0.07 ± 0.09, - 0.02 ± 0.08, - 0.02 ± 0.08, and - 0.06 ± 0.07 logMAR during the EDF CL wear, respectively, and 0.39 ± 0.17, 0.26 ± 0.15, 0.04 ± 0.12, - 0.02 ± 0.08, and - 0.09 ± 0.09 during the SV CL wear, respectively. The EDF CL showed better results than the SV CL at 0.3, 0.4, and 0.7 m (p < 0.05). There were no significant differences in contrast sensitivity between the EDF and SV CLs at 1.5 cycles per degree under all conditions; however, the sensitivity of the EDF CL was generally worse than that of the SV CL from the middle to high spatial frequencies. Stereopsis at 40 cm was significantly better in the EDF CL wear than in the SV CL wear (p < 0.05).

CONCLUSIONS

The EDF CL substantially improved visual acuity at near to intermediate distances in IOL-implanted eyes. However, far visual acuity decreased under low-contrast conditions, and contrast sensitivity slightly declined at the middle to high spatial frequencies.

The Relationship Between Vision and Comfort in Contact Lens Wear

OBJECTIVE

Understand relationship between vision and comfort in contact lens (CL) wear.

METHODS

Retrospective analysis of five trials using similar protocols with nonpresbyopic (NP) myopes or presbyopic participants (Px) wearing various simultaneous-image designs (SM) and single-vision (SV) CL (NP only). Questionnaires (vision satisfaction, vision clarity: distance/intermediate/near, comfort) on 1 to 10 scale were administered 1 week after fitting. Vision/comfort relationship was analyzed using linear mixed model and presented as regression coefficient with 95% confidence intervals (CIs).

RESULTS

Vision ratings correlated with comfort ratings, although this varied depending on type of vision rating and Px category. Vision satisfaction influenced comfort for the NP-SV group (slope: 0.8; 95% CI: 0.58-1.01, P≤0.001), but was significantly lower in the presbyopic group (slope: 0.38; 95% CI: 0.33-0.42; P≤0.001). Controlling for lens material obtained similar results. In the reverse relationship, comfort had a significant impact on vision satisfaction, although again at varying levels for each Px group. NP-SV demonstrated the weakest relationship (slope: 0.47; 95% CI: 0.35-0.59, P≤0.001) in comparison to NP-SM and P-SM groups.

CONCLUSION

Vision and comfort in CL wear are inter-related. Consideration of Px characteristics, visual stimulus, and CL comfort needs to be accounted for when assessing overall CL experience.

Impact of the pupil size - central optical zone diameter relationship on visual performance in aspheric multifocal contact lenses

PURPOSE

To determine the impact of different central optical zone diameters (COZDs), obtained from pupil size, on the visual performance of presbyopic subjects fitted with centre-distance simultaneous-image multifocal contact lenses (SIMCLs).

METHODS

Thirty-two presbyopic volunteers, between 45-58 years of age, participated in this prospective, controlled, double-blind study. Subjects were fitted with 5 centre-distance SIMCLs of variable COZD, determined from the measurement of pupil size under photopic light conditions and corresponding to 60, 70, 80, 90 and 100 % of pupil diameter. Subjects visual performance was evaluated through the measurement of distance, intermediate and near visual acuity (VA), "visual functional range" (VFR) obtained from the VA Defocus Curve (VADC) and Contrast Sensitivity Function (CSF), using a third-generation retina display iPad.

RESULTS

Statistically significant differences were obtained for both distance (p = 0.01) and intermediate (p = 0.001) VA amongst designs. Best results were obtained with 80 % and 90 % COZDs compared to 60 %. No significant differences in VFR (p > 0.05) were obtained amongst the different COZDs. 90 and 100 % COZDs offered statistically significant better results at 6 and 18 cycles per degree (cpd) in the CSF, compared to the 60 and 70 % designs.

CONCLUSIONS

SIMCLs with COZDs of 80-90 % and of 90-100% of photopic pupil diameter offered better distance and intermediate VA, without a decline in near performance, and superior contrast sensitivity at medium and high spatial frequencies respectively, compared to lower COZD designs.

Visual function, ocular surface integrity and symptomatology of a new extended depth-of-focus and a conventional multifocal contact lens

PURPOSE

To evaluate visual function, ocular surface integrity and dry eye symptoms with an extended depth-of-focus (EDOF) design and a conventional multifocal (MF) contact lens (CL) after 15 days of wear.

METHODS

A crossover single mask randomised clinical trial was conducted including 30 presbyopes who used an EDOF and a conventional MF CL (Biofinity MF) for 15 days each. Defocus curves, depth-of-focus range, contrast sensitivity (CS) under photopic and mesopic conditions (with and without glare) and subjective perception of halos and glare were evaluated. The ocular surface was evaluated through non-invasive Keratograph tear breakup time (NIKBUT), averaged tear breakup time (NIKBUT-avg), tear meniscus height (TMH), bulbar and limbal redness, and conjunctival and corneal staining. Dry eye symptoms were assessed with the OSDI questionnaire.

RESULTS

No statistically significant differences were found for defocus curves or depth-of-focus between the two CLs (both p > 0.05). Subjective perception of halos and glare was not significantly different between CLs. Statistically significant differences were observed for CS under mesopic conditions for low spatial frequencies (p = 0.008). None of the CL produced significant changes in NIKBUT, NIKBUT-avg, TMH or redness. No change in conjunctival staining was observed in 76.7 % and 73.3 % of participants for EDOF and Biofinity MF, respectively. No change in corneal staining was observed in 86.7 % and 83.3 % of participants for EDOF and Biofinity MF, respectively. No changes were observed in the symptomatology measured with OSDI questionnaire (p > 0.05).

CONCLUSIONS

Both CL for presbyopia offer good visual quality, preserve the ocular surface integrity and provide the patient with similar symptomatology levels after 15 days of lens wear.

Optical and Visual Quality With Physical and Visually Simulated Presbyopic Multifocal Contact Lenses

Purpose

As multifocal contact lenses (MCLs) expand as a solution for presbyopia correction, a better understanding of their optical and visual performance becomes essential. Also, providing subjects with the experience of multifocal vision before contact lens fitting becomes critical, both to systematically test different multifocal designs and to optimize selection in the clinic. In this study, we evaluated the ability of a simultaneous vision visual simulator (SimVis) to represent MCLs.

Methods

Through focus (TF) optical and visual quality with a center-near aspheric MCL (low, medium and high near adds) were measured using a multichannel polychromatic Adaptive Optics visual simulator equipped with double-pass, SimVis (temporal multiplexing), and psychophysical channels to allow measurements on-bench and in vivo. On bench TF optical quality of SimVis-simulated MCLs was obtained from double-pass (DP) images and images of an E-stimulus using artificial eyes. Ten presbyopic subjects were fitted with the MCL. Visual acuity (VA) and DP retinal images were measured TF in a 4.00 D range with the MCL on eye, and through SimVis simulations of the same MCLs on the same subjects.

Results

TF optical (on bench and in vivo) and visual (in vivo) quality measurements captured the expected broadening of the curves with increasing add. Root mean square difference between real and SimVis-simulated lens was 0.031/0.025 (low add), 0.025/0.015 (medium add), 0.019/0.011 (high add), for TF DP and TF LogMAR VA, respectively. A shape similarity metric shows high statistical values (lag κ = 0), rho = 0.811/0.895 (low add), 0.792/0.944 (medium add), and 0.861/0.915 (high add) for TF DP/LogMAR VA, respectively.

Conclusions

MCLs theoretically and effectively expand the depth of focus. A novel simulator, SimVis, captured the through-focus optical and visual performance of the MCL in most of the subjects. Visual simulators allow subjects to experience vision with multifocal lenses prior to testing them on-eye.

Translational Relevance

Simultaneous visual simulators allow subjects to experience multifocal vision non-invasively. We demonstrated equivalency between real multifocal contact lenses and SimVis-simulated lenses. The results suggest that SimVis is a suitable technique to aid selection of presbyopic corrections in the contactology practice.

Contrast sensitivity function with soft contact lens wear

PURPOSES

To compare contrast sensitivity function (CSF) with soft contact lens (SCL) and spectacles wear. To investigate the effect of a three-month period of SCL wear on CSF.

METHODS

Forty-seven myopic subjects with no history of contact lens (CL) wear were included in this longitudinal prospective study. CSF was measured with spectacles using the CSV-1000 (VectorVision, Greenvile, OH). Subsequently, subjects were fitted with a daily disposable lens (Nelfilcon-A, Stenofilcon-A or Nesofilcon-A) in one eye and a monthly disposable lens (Lotrafilcon-B, Comfilcon-A or Balafilcon-A) in the other eye and wore the same type of CLs for three months. CSF was measured again on the same day and after three months wearing CLs. Differences in CSF with spectacles and CLs on baseline and changes to CSF after three months of CLs wear were assessed. The effect of lens materials and wearing modality on CSF change was also investigated.

RESULTS

CSF was higher with CLs in comparison to the values with spectacles for spatial frequencies of 3, 6 and 12 cycles per degree (cpd) (p<0.05) while there was no difference for spatial frequency of 18 cpd (p=0.114). No significant difference was found in the CSF with CLs between baseline and after three months of lens wear (p>0.05). There was no difference in CSF between hydrogel and silicone CLs as well as when comparing daily with monthly wear CLs (p>0.05).

CONCLUSION

CSF is better with CLs than with spectacles. CSF values with CL are similar between baseline and after 3 months of lens wear.

Bifocal and Multifocal Contact Lenses for Presbyopia and Myopia Control

Bifocal and multifocal optical devices are intended to get images into focus from objects placed at different distances from the observer. Spectacles, contact lenses, and intraocular lenses can meet the requirements to provide such a solution. Contact lenses provide unique characteristics as a platform for implementing bifocality and multifocality. Compared to spectacles, they are closer to the eye, providing a wider field of view, less distortion, and their use is more consistent as they are not so easily removed along the day. In addition, contact lenses are also minimally invasive, can be easily exchangeable, and, therefore, suitable for conditions in which surgical procedures are not indicated. Contact lenses can remain centered with the eye despite eye movements, providing the possibility for simultaneous imaging from different object distances. The main current indications for bifocal and multifocal contact lenses include presbyopia correction in adult population and myopia control in children. Considering the large numbers of potential candidates for optical correction of presbyopia and the demographic trends in myopia, the potential impact of contact lenses for presbyopia and myopia applications is undoubtedly tremendous. However, the ocular characteristics and expectations vary significantly between young and older candidates and impose different challenges in fitting bifocal and multifocal contact lenses for the correction of presbyopia and myopia control. This review presents the recent developments in material platforms, optical designs, simulated visual performance, and the clinical performance assessment of bifocal and multifocal contact lenses for presbyopia correction and/or myopia progression control.

Optimization of the Light Sword Lens for Presbyopia Correction

Purpose

We propose and evaluate the modifications of a light sword lens (LSL) to obtain better performance for distance vision while maintaining good operation for near and intermediate vision.

Methods

The modifications consisted of assigning angular or circular windows for distance vision while rescaling the LSL profile in the remaining area of the element. The objective performance of the redesigned LSLs was verified numerically by the Strehl ratio and experimentally using correlation coefficients and Michelson contrast. Subjective assessments were provided by monocular visual acuity (VA) and contrast sensitivity (CS) through-focus curves for six patients with paralyzed accommodation. The tested object vergence range was [-4.0, 0.0] diopters (D). All experiments were conducted in a custom-made monocular visual simulator.

Results

Computational simulations and objective experiments confirmed the better performance of the modified LSL for the imaging of distant objects. The proposed angular and radial modulations resulted in flat VA and CS through-focus curves, indicating more uniform quality of vision with clearly improved distance vision. The VA provided by the modified LSL profiles showed a maximal improvement of 1.5 lines of acuity with respect to the VA provided by the conventional LSL at distance vision.

Conclusions

Optimized LSLs provide better imaging of distant objects while maintaining a large depth of focus. This results in comparable and acceptable quality for distance, intermediate, and near vision. Therefore, the modified LSLs appear to be promising presbyopia correctors.

Translational Relevance

The new design of LSL reveals an improved performance for all ranges of vision and becomes a promissory element for a real presbyopia correction in clinical applications.

Impact of monovision on dynamic accommodation of early presbyopes

PURPOSE

To examine the impact of monovision on dynamic changes in accommodation, pupil responses, spherical aberration and resultant image quality in early presbyopes.

METHODS

Refractive state, pupil size and spherical aberration levels were monitored in nine early presbyopes who exhibited some accommodation (40-50 years, mean = 42 ± 2.37 years) using a Shack-Hartmann aberrometer as a binocularly viewed stimulus stepped closer (from 2 m to 40 cm), or farther (from 40 cm to 2 m). Comparison data from two fully presbyopic (i.e. non-accommodating) subjects (ages 46 and 61 years) and two young adults (ages 26 and 29 years) were also collected. Each subject was fit with four different refractive strategies: (1) both eyes corrected for 2 m, (2) both eyes corrected for 40 cm, (3) monovision with the measured right eye corrected for 2 m and, (4) monovision with the right eye corrected for 40 cm. Monochromatic image quality was quantified using the AreaMTF metric.

RESULTS

When fit with monovision, the largest number of early presbyopes produce an accommodative response dominated by the right eye correction (distance or near) as the stimulus is abruptly changed from the retinal conjugate plane of one eye to that of the other eye. However, the accommodative responses in some early presbyopes were always dominated by the distance corrected eye, the near corrected eye, or by convergence. When the stimulus approached, the near corrected eye experienced high image quality only if there was no accommodative response. However, reduced image quality was observed if an accommodative response was initiated. Neither accommodation nor pupil response latencies were longer with monovision corrections compared with bilateral distance corrections (p > 0.05). In the early presbyopes, spherical aberration was reduced during near viewing, but primarily due to pupil miosis and not lens shape changes.

CONCLUSION

As the stimulus was abruptly changed from the retinal conjugate plane of the distance corrected eye to that of the near corrected eye, most early presbyopes fit with monovision accommodated, which resulted in a decline, not an increase in image quality in the near corrected eye. These results reveal a non-optimal accommodative strategy in early presbyopes fit with monovision.

Visual Performance of Daily-disposable Multifocal Soft Contact Lenses: A Randomized, Double-blind Clinical Trial

SIGNIFICANCE

The present study highlights the differences between modern daily-disposable multifocal soft contact lenses to assist eye care practitioners in fitting presbyopic contact lens wearers.

PURPOSE

The purpose of this study was to compare visual performance of three daily-disposable multifocal contact lenses.

METHODS

Presbyopes (n = 72) wore 1-Day Acuvue Moist Multifocal, BioTrue ONEday for Presbyopia, and Dailies AquaComfort Plus Multifocal for 1 week in a prospective, randomized, double-blind, crossover clinical trial. After 1 week, high- and low-contrast visual acuities (HCVA, LCVA) were measured between 6 m and 40 cm and stereopsis at 40 cm. Subjective performance was assessed with 1- to 10-point rating scales for clarity, ghosting, driving vision, vision stability, ease of focusing, overall vision satisfaction, and ocular comfort. Willingness to purchase was reported with categorical responses. Linear mixed models and χ tests were used for analysis, and level of significance was set at 5%.

RESULTS

BioTrue provided better HCVA and LCVA at distance than did Acuvue Moist (P ≤ .03). Subjectively, Acuvue Moist was rated lowest for distance clarity, distance ghosting, and driving vision (P ≤ .05). Acuvue Moist provided better HCVA at 70 to 40 cm and LCVA at 1 m to 40 cm than did BioTrue (P ≤ .01) and better LCVA at 1 m to 50 cm than did AquaComfort Plus (P ≤ .02). AquaComfort Plus also provided better HCVA and LCVA at 50 and 40 cm than did BioTrue (P ≤ .03). Acuvue Moist provided better stereopsis than did BioTrue (P = .02). Subjectively, BioTrue was rated lowest for near clarity (P ≤ .007) and lower than Acuvue Moist for intermediate clarity and near ghosting (P ≤ .04). No other differences were found between lenses (P > .05).

CONCLUSIONS

BioTrue had better distance performance compared with near, whereas Acuvue Moist performed conversely. AquaComfort Plus performed reasonably overall.

Accommodation in Early Presbyopes Fit with Bilateral or Unilateral Near Add

SIGNIFICANCE

When fit with monovision, most early presbyopes (aged 40 to 50 years) accommodated to near objects by focusing the distance corrected eye, leaving the near corrected eye myopically defocused with reduced image quality. A few were able to switch focus to the near corrected eye retaining a consistently focused image in one eye over a wider range of distances.

PURPOSE

The aim of this study was to examine accommodation behavior, pupil responses, and resultant image quality of early presbyopes fit with either bilateral or unilateral (monovision) near adds.

METHODS

Accommodative response and pupil size of 19 subjects (27 to 60 years), including 13 early presbyopes (40 to 50 years), were measured using an aberrometer as a binocularly viewed 20/40 letter E was moved from 2 m to 20 cm. Each subject was fit with different refractive strategies: bilateral distance correction, bilateral +2 diopters (D) near add, and unilateral +2 D near add placed over the measured right eye or unmeasured left eye. Monochromatic image quality was quantified using the Visual Strehl ratio metric.

RESULTS

With bilateral +2 D near add, all early presbyopes mostly refrained from accommodating (gain = 0.22 D/D) until the target approached closer than the 50-cm far point, and they then accommodated accurately until their maximum accommodative amplitude was reached. With monovision, most (10 of 13 early presbyopes) accommodated to focus the distance corrected eye, leaving the near corrected eye myopically defocused with reduced image quality. As stimulus distance became closer than their distance corrected eye's near point, they continued to exert maximum accommodation. Only two early presbyopes relaxed their accommodation to "switch" focus to the near corrected eye as target distance was reduced, and these two did not experience bilateral drop in image quality as stimulus distance became closer than the near point of the distance corrected eye.

CONCLUSIONS

Our data suggest that many early presbyopes will not initially adopt an accommodation strategy that optimizes image quality with monovision, but consistently accommodate to focus the distance corrected eye.

Presbyopia: Effectiveness of correction strategies

Presbyopia is a global problem affecting over a billion people worldwide. The prevalence of unmanaged presbyopia is as high as 50% of those over 50 years of age in developing world populations, due to a lack of awareness and accessibility to affordable treatment, and is even as high as 34% in developed countries. Definitions of presbyopia are inconsistent and varied, so we propose a redefinition that states "presbyopia occurs when the physiologically normal age-related reduction in the eye's focusing range reaches a point, when optimally corrected for distance vision, that the clarity of vision at near is insufficient to satisfy an individual's requirements". Strategies for correcting presbyopia include separate optical devices located in front of the visual system (reading glasses) or a change in the direction of gaze to view through optical zones of different optical powers (bifocal, trifocal or progressive addition spectacle lenses), monovision (with contact lenses, intraocular lenses, laser refractive surgery and corneal collagen shrinkage), simultaneous images (with contact lenses, intraocular lenses and corneal inlays), pinhole depth of focus expansion (with intraocular lenses, corneal inlays and pharmaceuticals), crystalline lens softening (with lasers or pharmaceuticals) or restored dynamics (with 'accommodating' intraocular lenses, scleral expansion techniques and ciliary muscle electrostimulation); these strategies may be applied differently to the two eyes to optimise the range of clear focus for an individual's task requirements and minimise adverse visual effects. However, none fully overcome presbyopia in all patients. While the restoration of natural accommodation or an equivalent remains elusive, guidance is given on presbyopic correction evaluation techniques.

Light disturbance with multifocal contact lens and monovision for presbyopia

Dysphotopsia affects a significant number of patients, particularly after visual correction with multifocal optical designs.

PURPOSE

Evaluate light distortion (LD) in two modalities of contact lens (CL) wear: multifocal (MF) and monofocal (MV).

METHODS

This was a randomized, double-masked, crossover study involving 20 presbyopic patients. Patients were randomized first into either MF or MV for 15 days of use with a 1 week wash-out period between each lens type. The LD was evaluated with the Light Distortion Analyzer (LDA, University of Minho) under monocular and binocular conditions. The light distortion index (LDI, %), among other parameters were analyzed. Subjective quality of vision was assessed with the Quality of Vision (QoV).

RESULTS

The LD showed an increase in all parameters in both CL modalities being significant for MV in the non-dominant eye (p < 0.030, for all LD parameters). For the MF, there was also a significant increase in LDI (p = 0.016) and in BFCrad (p = 0.022) in the non-dominant eye. After 15 days of MF lens wear, there was a significant decrease in all LD parameters (p < 0.002) in the dominant eye. Binocularly, a significant improvement from 1 to 15 days was observed for LDI (p = 0.009) and BFCrad (p = 0.0013) with MF. The QoV questionnaire showed no significant changes with neither CL.

CONCLUSIONS

Adaptation to light disturbances induced by MF CL is more effective compared to MV. Practitioners will have greater success if they prepare their patients for the adaptation required as their vision will get better and have less of an issue with light disturbance.

A Survey of Presbyopic Contact Lens Wearers in a University Setting

PURPOSE

To determine why presbyopic patients discontinue contact lens wear and describe their opinions of comfort and visual quality with contact lenses.

METHODS

A survey assessing current age, gender, contact lens material/design, and opinions of contact lens comfort and visual quality was mailed to 2400 presbyopic patients (age 40 years and older) that have had eye exams in the Ohio State University College of Optometry's Contact Lens Services over the last 4 years.

RESULTS

A total of 496 surveys were analyzed. The mean age of survey respondents was 57 ± 9 years, and 68% of the sample was female. Permanent discontinuation of contact lens wear was reported by 15%. No association was found between contact lens discontinuation and age (p = 0.7), gender (p = 0.2), age of beginning contact lens wear (p = 0.1), or contact lens material (p = 0.1). Poor vision (38%), discomfort (34%), convenience (20%), and cost (6%) were the primary reported reasons for discontinuation. There was no difference between the proportion of subjects reporting "poor vision" as their primary discontinuation reason and those reporting "discomfort" (p = 0.7). Discontinued wearers had a worse overall opinion of their distance (p = 0.03), intermediate (p = 0.01), and near vision (p = 0.002) compared to subjects who were still wearing their contact lenses.

CONCLUSIONS

Discomfort has been reported as the primary reason for contact lens discontinuation. In this presbyopic population, dissatisfaction with vision and discomfort were reported equally as often as primary reasons for discontinuation. As well, subjects who ceased contact lens wear had worse overall opinions of their vision at all distances than current contact lens wearers. The results of this survey suggest that presbyopes have unique demands and opinions related to contact lens wear.

Short-term comparison between extended depth-of-focus prototype contact lenses and a commercially-available center-near multifocal

PURPOSE

To compare the visual performance of prototype contact lenses which extend depth-of-focus (EDOF) by deliberate manipulation of multiple higher-order spherical aberration terms and a commercially-available center-near lens (AIR OPTIX Aqua Multifocal, AOMF).

METHODS

This was a prospective, cross-over, randomized, single-masked (participant), short-term clinical trial where 52 participants (age 45-70 years) were stratified as low, medium or high presbyopes and wore EDOF and AOMF on different days. Objective measures comprised high and low contrast visual acuity (HCVA/LCVA, logMAR), and contrast sensitivity (log units) at 6m; HCVA at 70cm, 50cm and 40cm and stereopsis (seconds of arc) at 40cm. HCVA at 70cm, 50cm and 40cm were measured as "comfortable acuity" rather than conventional resolution acuity. Subjective measures comprised clarity-of-vision and ghosting at distance, intermediate and near, overall vision satisfaction and ocular comfort (1-10 numeric rating scale) and lens purchase (yes/no response). Statistical analysis included repeated measures ANOVA, paired t-tests and McNemar's test.

RESULTS

Significant differences between lens types were independent of strata (p≥0.119). EDOF was significantly better than AOMF for HCVA at 40cm (0.42±0.18 vs. 0.48±0.22, p=0.024), stereopsis (98±88 vs. 141±114, p<0.001), clarity-of-vision at intermediate (8.5±1.6 vs. 7.7±1.9, p=0.006) and near (7.3±2.5 vs. 6.2±2.5, p=0.005), lack-of-ghosting (p=0.012), overall vision satisfaction (7.5±1.7 vs. 6.4±2.2, p<0.001) and ocular comfort (9.0±1.0 vs. 8.3±1.7, p=0.002). Significantly more participants chose to only-purchase EDOF (33% vs. 6%, p=0.003).). There were no significant differences between lens types for any objective measure at 6m or clarity-of-vision at distance (p≥0.356).

CONCLUSIONS

EDOF provides better intermediate and near vision performance in presbyopes than AOMF with no difference for distance vision during short-term wear.

Soft multifocal simultaneous image contact lenses: a review

Soft multifocal simultaneous image contact lenses have boomed in recent years due to the growing number of presbyopic patients demanding visual solutions, allowing them to maintain their current standard of living. The concept of 'simultaneous image' is based on blur interpretation and/or blur tolerance of superimposed multiple images on the retina formed by various powers of a contact lens. This is the basis for a specific type of multifocal contact lens developed for the compensation of presbyopia. Manufacturers have released a great variety of soft simultaneous image lens designs to meet different patient needs but their fitting is still unsatisfactory in some cases. Some presbyopes discontinue wearing contact lenses due to some limitations in visual quality and comfort that can be overcome with an appropriate contact lens selection based on a comprehensive pre-fitting evaluation. This paper aims to review the different types of soft multifocal contact lenses that are currently available for presbyopic correction and to define the steps and factors crucial for their fitting, such as pupil, aberrations, accommodation and centring. A discussion about useful tools to achieve a customised fitting leading to a successful outcome, such as the defocus curve, power profile and questionnaires, is performed.

Testing vision with angular and radial multifocal designs using Adaptive Optics

Multifocal vision corrections are increasingly used solutions for presbyopia. In the current study we have evaluated, optically and psychophysically, the quality provided by multizone radial and angular segmented phase designs. Optical and relative visual quality were evaluated using 8 subjects, testing 6 phase designs. Optical quality was evaluated by means of Visual Strehl-based-metrics (VS). The relative visual quality across designs was obtained through a psychophysical paradigm in which images viewed through 210 pairs of phase patterns were perceptually judged. A custom-developed Adaptive Optics (AO) system, including a Hartmann-Shack sensor and an electromagnetic deformable mirror, to measure and correct the eye's aberrations, and a phase-only reflective Spatial Light Modulator, to simulate the phase designs, was developed for this study. The multizone segmented phase designs had 2-4 zones of progressive power (0 to +3D) in either radial or angular distributions. The response of an "ideal observer" purely responding on optical grounds to the same psychophysical test performed on subjects was calculated from the VS curves, and compared with the relative visual quality results. Optical and psychophysical pattern-comparison tests showed that while 2-zone segmented designs (angular & radial) provided better performance for far and near vision, 3- and 4-zone segmented angular designs performed better for intermediate vision. AO-correction of natural aberrations of the subjects modified the response for the different subjects but general trends remained. The differences in perceived quality across the different multifocal patterns are, in a large extent, explained by optical factors. AO is an excellent tool to simulate multifocal refractions before they are manufactured or delivered to the patient, and to assess the effects of the native optics to their performance.

Randomized Crossover Trial of Silicone Hydrogel Presbyopic Contact Lenses

PURPOSE

To assess the performance of four commercially available silicone hydrogel multifocal monthly contact lens designs against monovision.

METHODS

A double-masked randomized crossover trial of Air Optix Aqua multifocal, PureVision 2 for Presbyopia, Acuvue OASYS for Presbyopia, Biofinity multifocal, and monovision with Biofinity contact lenses was conducted on 35 presbyopes (54.3 ± 6.2 years). After 4 weeks of wear, visual performance was quantified by high- and low-contrast visual acuity under photopic and mesopic conditions, reading speed, defocus curves, stereopsis, halometry, aberrometry, Near Activity Visual Questionnaire rating, and subjective quality of vision scoring. Bulbar, limbal, and palpebral hyperemia and corneal staining were graded to monitor the impact of each contact lens on ocular physiology.

RESULTS

High-contrast photopic visual acuity (p = 0.102), reading speed (F = 1.082, p = 0.368), and aberrometry (F = 0.855, p = 0.493) were not significantly different between presbyopic lens options. Defocus curve profiles (p < 0.001), stereopsis (p < 0.001), halometry (F = 4.101, p = 0.004), Near Activity Visual Questionnaire (F = 3.730, p = 0.007), quality of vision (p = 0.002), bulbar hyperemia (p = 0.020), and palpebral hyperemia (p = 0.012) differed significantly between lens types, with the Biofinity multifocal lens design principal (center-distance lens was fitted to the dominant eye and a center-near lens to the nondominant eye) typically outperforming the other lenses.

CONCLUSIONS

Although ocular aberration variation between individuals largely masks the differences in optics between current multifocal contact lens designs, certain design strategies can outperform monovision, even in early presbyopes.

Association between Ocular Sensory Dominance and Refractive Error Asymmetry

Purpose

To investigate the association between ocular sensory dominance and interocular refractive error difference (IRED).

Methods

A total of 219 subjects were recruited. The refractive errors were determined by objective refraction with a fixation target located 6 meters away. 176 subjects were myopic, with 83 being anisometropic (IRED ≥ 0.75 D). 43 subjects were hyperopic, with 22 being anisometropic. Sensory dominance was measured with a continuous flashing technique with the tested eye viewing a Gabor increasing in contrast and the fellow eye viewing a Mondrian noise decreasing in contrast. The log ratio of Mondrian to Gabor’s contrasts was recorded when a subject just detected the tilting direction of the Gabor during each trial. T-test was used to compare the 50 values collected from each eye, and the t-value was used as a subject’s ocular dominance index (ODI) to quantify the degree of ocular dominance. A subject with ODI ≥ 2 (p < 0.05) had clear dominance and the eye with larger mean ratio was the dominant one. Otherwise, a subject had an unclear dominance.

Results

The anisometropic subjects had stronger ocular dominance in comparison to non-anisometropic subjects (rank-sum test, p < 0.01 for both myopic and hyperopic subjects). In anisometropic subjects with clear dominance, the amplitude of the anisometropia was correlated with ODI values (R = 0.42, p < 0.01 in myopic anisometropic subjects; R = 0.62, p < 0.01 in hyperopic anisometropic subjects). Moreover, the dominant eyes were more myopic in myopic anisometropic subjects (sign-test, p < 0.05) and less hyperopic in hyperopic anisometropic subjects (sign-test, p < 0.05).

Conclusion

The degree of ocular sensory dominance is associated with interocular refractive error difference.

Visual Performance of a Multifocal Contact Lens versus Monovision in Established Presbyopes

PURPOSE

To compare subjective and objective visual performance of the Air Optix Aqua Multifocal lens to monovision in a group of subjects requiring a medium level of reading-addition power.

METHODS

Fifty participants with reading additions between 1.25 and 2.00 diopters (inclusive) were randomized into a prospective, crossover clinical trial. They wore monovision and multifocals for 2 weeks in a randomized order. High- and low-contrast logMAR (logarithm of the minimum angle of resolution) acuity and stereopsis were measured at the beginning and end of each period. During each phase, participants performed specific tasks followed by subjective rating surveys and also completed satisfaction rating surveys on days 3, 7, and 12; all were transferred in real time using BlackBerry smartphones. A general rating survey was completed at the dispensing and 2-week visits.

RESULTS

Forty-nine participants completed the study (mean age, 52 years). Distance and near high- and low-contrast acuities were significantly better (p < 0.05) with monovision at all visits. High-contrast intermediate acuity was only better (p < 0.05) with multifocals after 2 weeks. Stereopsis was equivalent after 2 weeks, but better (p < 0.05) with multifocals at dispensing. Subjective ratings were generally equivalent between modalities although there was a trend for multifocals to be rated higher for focus changing and driving, whereas monovision tended to be rated higher for near tasks. For both corrections, the satisfaction survey showed no significant change between days 3, 7, and 12, and the general survey showed that comfort was maintained but subjective vision ratings decreased significantly over the 2 weeks. Twenty-five participants (51%) preferred multifocals, 18 (37%) preferred monovision, and the remaining 6 (12%) declared both unacceptable.

CONCLUSIONS

In this cohort, distance and near acuities were better with monovision, whereas the subjective ratings tended to favor the Air Optix Aqua Multifocal, with the exception of near performance. Preference was statistically similar between both corrections, with a trend toward preferring the multifocal.

Optical power distribution of refractive and aspheric multifocal contact lenses: Effect of pupil size

PURPOSE

To evaluate the power profile within the optic zone of different designs of multifocal contact lenses (CLs) and to analyze how the effect of pupil size could impact on their optical performance.

METHODS

The optical power distribution within the optic zones of multifocal CLs was measured by the Nimo TR1504 (LAMBDA-X, Belgium). The multifocal CLs under study were the Acuvue Bifocal, the Acuvue Oasys for Presbyopia, the PureVision Multifocal and the PureVision 2 for Presbyopia. Each design was considered in all their available addition powers. All lenses had a nominal power of -3.0D. At the same time, three lenses of each model were considered and five consecutive readings of each lens were performed.

RESULTS

The results show that the PureVision Multifocal and the PureVision 2 for Presbyopia have aspheric power profiles. Both designs showed aspheric center-near designs with a smoother progression of the optical power in the PureVision 2 for Presbyopia. The Acuvue Bifocal and the Acuvue Oasys for Presbyopia are shown to have concentric alternating near and far zones. Apart from the refractive rings, the Acuvue Oasys for Presbyopia showed an increase in negative (or less positive) values toward the periphery of the lens.

CONCLUSIONS

Besides the refraction, the knowledge of the power profiles of multifocal CLs and the effect of pupil size on the optical distribution of these lenses could be crucial to understand the performance of these designs when they are fitted.

How aquatic water-beetle larvae with small chambered eyes overcome challenges of hunting under water

A particularly unusual visual system exists in the visually guided aquatic predator, the Sunburst Diving Beetle, Thermonectus marmoratus (Coleoptera: Dytiscidae). The question arises: how does this peculiar visual system function? A series of experiments suggests that their principal eyes (E1 and E2) are highly specialized for hunting. These eyes are tubular and have relatively long focal lengths leading to high image magnification. Their retinae are linear, and are divided into distinct green-sensitive distal and UV and polarization-sensitive proximal portions. Each distal retina, moreover, has many tiers of photoreceptors with rhabdomeres the long axis of which are peculiarly oriented perpendicular to the light path. Based on detailed optical investigations, the lenses of these eyes are bifocal and project focused images onto specific retinal tiers. Behavioral experiments suggest that these larvae approach prey within their eyes' near-fields, and that they can correctly gauge prey distances even when conventional distance-vision mechanisms are unavailable. In the near-field of these eyes object distance determines which of the many retinal layers receive the best-focused images. This retinal organization could facilitate an unusual distance-vision mechanism. We here summarize past findings and discuss how these eyes allow Thermonectus larvae to be such successful predators.

In vitro power profiles of multifocal simultaneous vision contact lenses

PURPOSE

To evaluate the power profile of multifocal contact lenses (CLs) using a new technology based on quantitative deflectometry.

METHODS

The Nimo TR1504 was used to analyze the power distribution of multifocal CLs. The CLs under study were: Air Optix Aqua Multifocal Low, Medium and High Addition and Focus Progressives. Three lenses of each model were considered.

RESULTS

All multifocal CLs showed a power profile characterized by a change toward more positive power values when aperture sizes become smaller. The near refractive addition of the lenses under study was +2.61 D, +1.44 D, +1.30 D and +0.30 D for the Focus Progressives, the Air Optix Aqua Multifocal High, Medium Add and Low Add, respectively. The refractive power of the Focus Progressives did not reach the value of the nominal distance power until a radial distance of 0.9 mm from the center of the lens. For the Air Optix Aqua Multifocal Low Add the distance nominal power was reached at a radial distance of 1.5mm from the center of the lens, whereas this occurred at a distance of 1.8mm for the Air Optix Aqua Multifocal Medium and High Add.

CONCLUSION

The relation between the pupil diameter of the patients and the power profile of these CLs has a crucial implication on the final distance correction and near addition that these lenses provide to patients. Practitioners should know the power profile of these CLs and measure the pupil diameter of each patient in different situations in order to carry out a customized fitting.

Adaptation to multifocal and monovision contact lens correction

PURPOSE

To compare visual performance with the Biofinity multifocal (MF) contact lens with monovision (MV) with the Biofinity single-vision contact lens.

METHODS

A crossover study of 20 presbyopic patients was conducted. Patients were randomized first into either an MF or an MV lens for 15 days for each modality, with a washout period between each lens type. Measurements included monocular and binocular high- and low-contrast logarithm of the minimum angle of resolution visual acuity (VA) at distance and near visions, binocular distance contrast sensitivity function, and near stereoacuity.

RESULTS

At 15 days, patients lost fewer than two letters (half a line of VA) of binocular distance and near VA, with the MF and MV lens under high- and low-contrast conditions (P > 0.05 for both comparisons). No statistically significant differences were seen in binocular VA at near or distance with either lens. However, the monocular distance VA improved significantly in the nondominant eye, with the MF lens by one line over the 15-day period under high-contrast (P = 0.023) and low-contrast (P = 0.035) conditions; this effect was not seen with the MV lens. Contrast sensitivity function was within the normal limits with both lenses. The stereoacuity was significantly (P < 0.01) better with MF than with MV.

CONCLUSIONS

Multifocal contact lens correction provided satisfactory levels of VA comparable with MV without compromising stereoacuity in this crossover study. The near vision significantly improved in the dominant eye, and the distance vision improved in the nondominant eye from 1 to 15 days with the MF lens, suggesting that patients adapted to the multifocality overtime, whereas this was not true for MV.

Visual performance of a multifocal toric soft contact lens

PURPOSE

To evaluate the visual performance of the Proclear multifocal toric contact lens (CL; CooperVision, US) for both presbyopia and astigmatism correction.

METHODS

In this crossover study design, 20 presbyopic subjects with astigmatism were fitted in a random order with either Proclear multifocal toric CL or Proclear toric single vision distance CL (DCL) combined with reading spectacles. After 1 month, high-contrast distance visual acuity, near high-contrast visual acuity, distance contrast sensitivity (CS) under photopic and mesopic conditions without and with glare, near CS, defocus curve, and stereopsis were measured. Subjects were then refitted with the alternative correction, and the procedure was repeated.

RESULTS

Repeated measures analysis of variance revealed differences in visual acuity and CS (p < 0.001) between groups. Mean binocular distance visual acuity and near visual acuity obtained with multifocal toric CL were -0.01 ± 0.03 logMAR and -0.04 ± 0.06 logMAR, respectively. The mean distance CS with the multifocal toric CL was within normal limits under photopic and mesopic conditions. Under photopic conditions, distant CS was better with distance CL than with multifocal toric CL only at 18 cycles/degree. Under mesopic conditions without and with glare, there were differences between both CLs in distant CS for all spatial frequencies. There were differences between the two CLs in near CS for all spatial frequencies. Mean values of stereopsis obtained with multifocal toric CLs and with the DCL combined with reading glasses were 62 ± 12 sec of arc and 59 ± 12 sec of arc, respectively (p = 0.06). Near range of clear vision with the multifocal toric CLs was 1.55 ± 0.33D.

CONCLUSIONS

The results of this study suggest that the multifocal toric CL studied is a good option to compensate both presbyopia and astigmatism, providing an optimal distance and near visual quality without compromising the stereopsis.

Visual performance comparison between contact lens-based pinhole and simultaneous vision contact lenses

BACKGROUND

The aim was to evaluate the visual performance provided with a contact lens-based pinhole design against a simultaneous vision multifocal contact lens.

METHODS

In a cross-over study at the University of Valencia, 22 presbyopic patients were evaluated using an artificial pupil fitted on the non-dominant eye and the simultaneous vision PureVision Multifocal contact lenses. After one month of contact lens wear, binocular distance visual acuity (BDVA), binocular near visual acuity (BNVA), defocus curve, binocular distance contrast sensitivity, binocular near contrast sensitivity, and stereoacuity were measured, under photopic conditions (85 cd/m(2)). In addition, binocular distance visual acuity and binocular distance contrast sensitivity were examined under mesopic conditions (5 cd/m(2)).

RESULTS

Mean binocular distance visual acuity for pinhole and PureVision Multifocal were 0.02 ± 0.04 and 0.01 ± 0.04 logMAR under photopic conditions and 0.16 ± 0.06 and 0.12 ± 0.04 logMAR for binocular near visual acuity under mesopic conditions, respectively. No statistically significant differences were found between both types of lenses at distance for both lighting levels and intermediate distances (p > 0.05). There was a significant difference at near vision under photopic conditions (p = 0.03). Binocular distance contrast sensitivity revealed statistically significant differences between the pinhole system and PureVision Multifocal for six and 12 cpd (cycles per degree) spatial frequencies at the two luminance levels, while for near vision, differences were also significant for 18 cpd. Stereoacuity was better with PureVision Multifocal (127 ± 49.3 seconds of arc) compared with the pinhole lens (220.2 ± 32.3 seconds of arc, p = 0.004).

CONCLUSION

Pinhole and PureVision Multifocal contact lenses provide good binocular vision for distance and functional intermediate vision. Although it was better with the PureVision Multifocal, near vision was not satisfactory for either of the two contact lens options.

Effect of multizone refractive multifocal contact lenses on standard automated perimetry

PURPOSE

The aim of this study was to evaluate whether the creation of 2 foci (distance and near) provided by multizone refractive multifocal contact lenses (CLs) for presbyopia correction affects the measurements on Humphreys 24-2 Swedish interactive threshold algorithm (SITA) standard automated perimetry (SAP).

METHODS

In this crossover study, 30 subjects were fitted in random order with either a multifocal CL or a monofocal CL. After 1 month, a Humphrey 24-2 SITA standard strategy was performed. The visual field global indices (the mean deviation [MD] and pattern standard deviation [PSD]), reliability indices, test duration, and number of depressed points deviating at P<5%, P<2%, P<1%, and P<0.5% on pattern deviation probability plots were determined and compared between multifocal and monofocal CLs.

RESULTS

Thirty eyes of 30 subjects were included in this study. There were no statistically significant differences in reliability indices or test duration. There was a statistically significant reduction in the MD with the multifocal CL compared with monfocal CL (P=0.001). Differences were not found in PSD nor in the number of depressed points deviating at P<5%, P<2%, P<1%, and P<0.5% in the pattern deviation probability maps studied.

CONCLUSIONS

The results of this study suggest that the multizone refractive lens produces a generalized depression in threshold sensitivity as measured by the Humphreys 24-2 SITA SAP.

Visual comparison of an artificial pupil contact lens to monovision

PURPOSE

To assess and compare the effects of contact-lens based artificial pupil design and monovision correction on visual performance.

METHODS

In a cross-over study design, 22 presbyopic patients (age range 50 to 64 years) were evaluated using artificial pupil contact lens on the non-dominant eye and monovision. After 1 month, binocular distance visual acuity (BDVA), binocular near visual acuity (BNVA), defocus curve, binocular distance contrast sensitivity, binocular near contrast sensitivity, and stereoacuity were measured, under photopic conditions (85 cd/m2), in each patient after contact lens fitting. Moreover, BDVA and binocular distance contrast sensitivity were examined under mesopic conditions (5 cd/m2).

RESULTS

Average artificial pupil contact lens and monovision BDVA were 0.02 ± 0.04 and 0.00 ± 0.09 logMAR for photopic conditions, and 0.16 ± 0.06 and 0.13 ± 0.12 logMAR for binocular near visual acuity under mesopic conditions, respectively. No statistically significant differences were found between the two types of lenses at distance for both lighting levels (p > 0.05), but there were, however, significant differences at intermediate distances and near vision (p < 0.05). Binocular distance contrast sensitivity revealed statistically significant differences between artificial pupil contact lens and monovision for 1.5 cycles per degree (cpd) under photopic conditions, and 12 and 18 cpd under mesopic conditions (p < 0.05), respectively. Statistically significant differences for all spatial frequencies except for 1.5 cpd were found at near vision (p < 0.05). The mean values of stereoacuity obtained for artificial pupil contact lens (221 ± 32 sec arc) were slightly worse than for monovision correction (210 ± 49 sec arc), and statistically significant differences were not found (p = 0.23).

CONCLUSIONS

Monovision performed better than an artificial pupil contact lens of the same material for near visual acuity and near contrast sensitivity. Only, the artificial pupil contact lens provides better intermediate visual acuity.

Changes in accommodative responses with multifocal contact lenses: a pilot study

PURPOSE

To evaluate induced changes in pupil and accommodative response for different accommodative stimuli with three different multifocal contact lenses (CLs).

METHODS

Accommodative and pupil responses with three aspheric multifocal CLs of simultaneous focus center near (PureVision Low Add, PureVision High Add and Focus Progressives) for two accommodative stimuli of -2.5 and -4.00 D were recorded in 10 young subjects. Accommodative response, peak velocity, and time constant of accommodation and pupil constriction were assessed. The measurements were evaluated in all the participants with distance-single vision CLs and with the three multifocal CLs. The monocular measurements were performed in a random sequence for each participant. All parameters were measured with a Hartmann-Shack aberrometer (IRX-3; Imagine Eyes, Orsay, France).

RESULTS

Differences were not found in accommodation response for both accommodative stimuli studied between the single vision lens and the three different multifocal CLs (p > 0.05 for both stimuli). For the 2.5 D stimulus, significant differences were not found in peak velocity and time constant between the single vision lens and the three different multifocal CLs (p > 0.05 for all situations); in amplitude of pupil constriction, differences were only found for the situation with PureVision High Add, where the value was lower than the single vision lens (p = 0.015). For the 4.00 D stimulus, differences with single vision lens in peak of velocity and time constant were only found with PureVision Low Add, where the peak velocity value was higher and the time constant was lower (p = 0.024 and p = 0.032 for peak of velocity and time constant, respectively); for amplitude of pupil constriction differences were not found (p > 0.05).

CONCLUSIONS

Data obtained in this pilot study suggest that in young observers, the multifocal CLs studied do not induce large changes in accommodative system compared with the single vision lens.

Visual performance with simultaneous vision multifocal contact lenses

PURPOSE

  The aim was to assess visual performance after PureVision high addition multifocal contact lens (PM) fitting through contrast sensitivity measured under different illumination levels for both distance and near.

METHODS

  In a cross-over study, 20 presbyopic patients were randomly assigned to PM or spectacles. Near contrast sensitivity was measured with the Vistech VCTS 6500 system. Distance contrast sensitivity and distance visual acuity (VA) were measured with the Functional Vision Analyser under photopic (85 cd/m(2) ) and mesopic (3.0 cd/m(2) ) conditions, the latter also under two levels of induced glare: 1.0 lux and 28 lux. Near VA was measured by logMAR charts under approximately 80 cd/m(2) luminance settings.

RESULTS

  Average monocular spectacle corrected and PM VA were -0.02 ± 0.05 and 0.03 ± 0.05 logMAR for distance photopic, 0.16 ± 0.10 and 0.23 ± 0.07 logMAR for distance mesopic and -0.03 ± 0.05 and 0.05 ± 0.06 logMAR for near photopic, respectively. Average binocular spectacle corrected and PM VA were -0.05 ± 0.07 and -0.01 ± 0.03 logMAR for distance photopic, 0.10 ± 0.06 and 0.18 ± 0.05 logMAR for distance mesopic and -0.08 ± 0.06 and 0.02 ± 0.05 logMAR for near photopic, respectively. Statistically significant differences were found between the contrast sensitivity with the two types of correction for both distance and near, with spectacle correction being better in all cases.

CONCLUSION

  PureVision multifocal contact lenses preserve good VA and good visual performance under real-life conditions.