Simulation of daily soft multifocal contact lenses using SimVis Gekko: from in-vitro and computational characterization to clinical validation.

Multifocal contact lenses (MCLs) are one of the solutions to correct presbyopia, but their adoption is not widespread. To address this situation, visual simulators can be used to refine the adaptation process. This study aims to obtain accurate simulations for a visual simulator (SimVis Gekko; 2EyesVision) of daily soft MCL designs from four manufacturers. In-vitro characterization of these MCLs-several powers and additions- was obtained using NIMO TR-1504. From the averaged relative power profiles across powers, phase maps were reconstructed and the Through-Focus Visual Strehl metric was calculated for each MCL design. The SimVis Gekko simulation corresponding to each MCL design was obtained computationally and bench-validated. Finally, the MCL simulations were clinically validated involving presbyopic patients. The clinical validation results show a good agreement between the SimVis Gekko simulations and the real MCLs for through-focus visual acuity (TF-VA) curves and VA at three real distances. All MCL designs showed a partial correlation higher than 0.90 and a Root Mean Square Error below 0.07 logMAR between the TF-VA of simulations and Real MCLs across subjects. The validity of the simulation approach using SimVis Gekko and in-vitro measurements was confirmed in this study, opening the possibility to accelerate the adaptation of MCLs.

Visual quality assessment and comparison of two multifocal scleral lens designs.

PURPOSE: To analyze the visual quality of a new multifocal scleral lens with a customized decentred optic zone compared to a conventional design by measuring visual acuity, contrast sensitivity function, stereopsis, subjective vision and comfort after one month of wear. METHODS: Nineteen presbyopic subjects were fitted with two multifocal scleral lens designs: a conventional multifocal and a customized decentred optical zone design. All subjects wore both scleral lens designs for one month with a two-week washout period. The main variables evaluated included high and low-contrast visual acuity under photopic and mesopic light conditions, binocular defocus curves, contrast sensitivity function and a visual analogue scale (VAS) for subjective vision and comfort. RESULTS: Comparing the two scleral lens designs, statistically significant differences in visual acuity were found, highlighting the improvement in more than one chart line (6 letters) for low contrast near tests under photopic light conditions with the decentred optics lens design. VAS questionnaire scores also showed a significant improvement in distance and overall subjective vision with the decentred optics lenses. Contrast sensitivity function showed an improvement with decentred multifocal lenses at all spatial frequencies measured, being statistically significant for 12 cycles per degree. No differences in stereoacuity were found. CONCLUSION: Multifocal scleral lenses with a customized decentred optical zone proved to be a promising refractive correction in presbyopic subjects after one month of wear, offering good comfort and visual quality under photopic and mesopic light conditions.

Visual performance of new affordable and auto-adherent lenses for presbyopia correction.

Presbyopia is a visual condition that affects all of us, evolving with time, reducing the range of accommodation and the ability to work at near. Reading glasses, bifocals or multifocal lenses are the most common solutions. In this work, we demonstrate the near visual performance of new elastomeric auto-adherent lenses developed for the correction of presbyopia. Visual acuity and contrast sensitivity were measured in 10 presbyopic subjects. The results showed that wearing either conventional trial ophthalmic lenses or the new elastomeric lenses provided similar visual quality. These elastomeric lenses can be placed in, or removed from the distance-vision spectacles of the wearers, providing an affordable solution for correcting presbyopia at its clinical onset, which might be especially useful in subjects with different refractive error in each eye and for those with astigmatism.

Factors influencing the need and willingness for presbyopic correction: a cross sectional study from south India.

Presbyopia is an age-related physiological phenomenon in which eye gradually losses its ability to accommodate. It is one of the leading causes of visual impairment worldwide, especially in adults above the age of 40. If uncorrected, it can significantly impair a patient's quality of life. This study aims to evaluate the factors which affects patient's need and willingness to accept presbyopic correction. This cross-sectional analytical study was carried out in a semi urban tertiary care hospital from Jan 2021 to June 2022 among patients aged 40 and above who presented to Outpatient department (OPD). Demographic details, medical history, presenting ocular complaints pertaining to presbyopia, spectacle use and decision regarding using near vision correction were noted. Ocular examination included refraction and ocular biometry. Factors that may have influenced complaints of presbyopia or willingness to accept presbyopic correction were analysed. Three hundred and forty two patients with a mean age of 48.55 ± 6.68 years were included. Of these, 262 (76.61%) patients presented with chief complaints related to presbyopia. Those with higher educational qualification (p = 0.031), hypermetropia (p = 0.021), shallower AC depth (p = 0.028) and on medications for systemic ailments (p = 0.01), were more likely to present with chief complaints attributable to presbyopia. Among them, those with higher educational qualifications (p = 0.02) and skilled workers were more likely to accept near vision glasses (p = 0.02), while those with lower Hb (p = 0.01) and myopia (p = 0.01) were less likely to accept correction for presbyopia. Among the 80 patients without chief complaints related to presbyopia, 35 (43.75%) were not willing to accept near vision glasses. Those with higher BMI (p = 0.04) and hypermetropes (p = 0.05) were more willing to accept presbyopic correction. Presbyopia constitutes a significant reason for patients above the age of 40 visiting eye care facility. Multiple socio-economic, systemic and ocular factors influenced both the chief complaints related to presbyopia and willingness to accept presbyopic correction.

The influence of large-diameter multifocal contact lens on ocular surface, visual quality, and visual function for presbyopic adults with dry eye syndromes.

This study investigated the influence of large-diameter multifocal contact lenses on the ocular surface, visual quality, and visual function for presbyopic adults with dry eye syndromes. The study enrolled 40-55-year-old adults with presbyopia and dry eye syndromes (DES). The subjects were randomly assigned to three groups wearing different designs of contact lenses (Proclear, SMR, and Optimum) for 6-8 h a day for two weeks. Ocular surface health, tear quality, visual quality, and visual function were measured before and after lens wear. No significant difference was observed across all three groups for the amount of conjunctival redness, blink frequency (lens on), and stereopsis vision before and after wearing. Although there seemed to be a significant declining trend for corneal staining and limbal redness, non-invasive tear break-up time (TBUT), and lipid layer thickness while lens wear, the measured values were all within the normal range. Vice-versa after lens removal, results also showed significant improvement on lipid layer thickness, blink frequency (lens off), and contact TBUT. A significant improvement was observed in the modulation transfer function (MTF) of the total area ratio after wearing contact lenses. In contrast, the MTF of the high-order aberration area ratio resulting from lens wear was lower than that of the baseline measurement. There are also significant improvements observed for SMR and Optimum regarding near visual acuity, near point of accommodation, and the subjective questionnaire (OSDI and VBP) scores. Although it is difficult to avoid a specific negative impact on the ocular surface and tear film, visual function and visual quality can still be positively improved, especially shown on larger diameter and distance-center designed multifocal contact lenses.

Presbyopia correction with multifocal contact lenses: Evaluation of silent reading performance using eye movements analysis.

PURPOSE: Many activities of daily living rely on reading, thus is not surprising that complaints from presbyopes originate in reading difficulties rather in visual acuity. Here, the effectiveness of presbyopia correction with multifocal contact lenses (CLs) is evaluated using an eye-fixation based method of silent reading performance. ΜETHODS: Visual performance of thirty presbyopic volunteers (age: 50 ± 5 yrs) was assessed monocularly and binocularly following 15 days of wear of monthly disposable CLs (AIR OPTIX™ plus HydraGlyde™, Alcon Laboratories) with: (a) single vision (SV) lenses - uncorrected for near (b) aspheric multifocal (MF) CLs. LogMAR acuity was measured with ETDRS charts. Reading performance was evaluated using standard IReST paragraphs displayed on a screen (0.4 logMAR print size at 40 cm distance). Eye movements were monitored with an infrared eyetracker (Eye-Link II, SR Research Ltd). Data analysis included computation of reading speed, fixation duration, fixations per word and percentage of regressions. RESULTS: Average reading speed was 250 ± 68 and 235 ± 70 wpm, binocularly and monocularly, with SV CLs, improving statistically significantly to 280 ± 67 (p = 0.002) and 260 ± 59 wpm (p = 0.01), respectively, with MF CLs. Moreover, fixation duration, fixations per word and ex-Gaussian parameter of fixation duration, µ, showed a statistically significant improvement when reading with MF CLs, with fixation duration exhibiting the stronger correlation (r = 0.79, p < 0.001) with improvement in reading speed. The correlation between improvement in VA and reading speed was moderate (r = 0.46, p = 0.016), as was the correlation between VA and any eye fixation parameter. CONCLUSION: Average silent reading speed in a presbyopic population was found improved with MF compared to SV CL correction and was faster with binocular compared to monocular viewing: this was mainly due to the faster average fixation duration and the lower number of fixations. Evaluating reading performance using eye fixation analysis could offer a reliable outcome of functional vision in presbyopia correction.

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.

Promotion of Protein Solubility and Reduction in Stiffness in Human Lenses by Aggrelyte-1: Implications for Reversing Presbyopia.

With aging, human lenses lose the ability to focus on nearby objects due to decreases in accommodative ability, a condition known as presbyopia. An increase in stiffness or decrease in lens elasticity due to protein aggregation and insolubilization are the primary reasons for presbyopia. In this study, we tested aggrelyte-1 (S,N-diacetyl glutathione diethyl ester) for its ability to promote protein solubility and decrease the stiffness of lenses through its dual property of lysine acetylation and disulfide reduction. Treatment of water-insoluble proteins from aged human lenses (58-75 years) with aggrelyte-1 significantly increased the solubility of those proteins. A control compound that did not contain the S-acetyl group (aggrelyte-1C) was substantially less efficient in solubilizing water-insoluble proteins. Aggrelyte-1-treated solubilized protein had significant amounts of acetyllysine, as measured by Western blotting and LC-MS/MS. Aggrelytes increased the protein-free thiol content in the solubilized protein. Aged mouse (7 months) and human (44-66 years) lenses treated with aggrelyte-1 showed reduced stiffness accompanied by higher free thiol and acetyllysine levels compared with those treated with aggrelyte-1C or untreated controls. Our results suggested that aggrelyte-1 reduced lens stiffness through acetylation followed by disulfide reduction. This proof-of-concept study paves the way for developing aggrelyte-1 and related compounds to reverse presbyopia.

A Review of Lens Biomechanical Contributions to Presbyopia.

Purpose: Presbyopia-the progressive loss of near focus with age-is primarily a result of changes in lens biomechanics. In particular, the shape of the ocular lens in the absence of zonular tension changes significantly throughout adulthood. Contributors to this change in shape are changes in lens biomechanical properties, continuous volumetric growth lens, and possibly remodeling of the lens capsule. Knowledge in this area is growing rapidly, so the purpose of this mini-review was to summarize and synthesize these gains.Methods: We review the recent literature in this field.Results: The mechanisms governing age-related changes in biomechanical properties remains unknown. We have recently shown that lens growth may be driven by zonular tension. The same mechanobiological mechanism driving lens growth may also lead to remodeling of the capsule, though this remains to be demonstrated.Conclusions: This mini-review focuses on identifying mechanisms which cause these age-related changes, suggesting future work which may elucidate these mechanisms, and briefly discusses ongoing efforts to develop a non-surgical approach for therapeutic management of presbyopia. We also propose a simple model linking lens growth and biomechanical properties.

[TREATMENTS FOR PRESBYOPIA].

INTRODUCTION: Presbyopia is the physiological, gradual, progressive loss of the ability to see clearly at near point which affects people as they age. It is primarily caused by the thickening and stiffening of the lens leading to an inability to adjust its shape to become convex enough to induce adequate plus power to see at short distances. Symptoms usually begin affecting individuals around 40 years of age, the most common being discomfort in or around the eyes after prolonged near work, blur at distance after near work, and eventually progressing to near blur, often with a natural tendency to distance the object by holding it farther away to try to see it better. At a certain point near tasks become impossible and the patient will seek an external solution. Various therapies are available and being developed to treat presbyopia, which include glasses, contact lenses, intraocular lens implants, corneal laser procedures, intracorneal implants, scleral alterations and pharmacological ocular drops. Untreated presbyopia negatively affects quality of life as well as the world productivity since presbyopia progresses from approximately an age when people are still an active part of the workforce. As the population and life expectancy grow, so will the number of presbyopes. This article will discuss the various options available to treat presbyopia.

Exploring the Experience of Living with and Managing Presbyopia.

SIGNIFICANCE: Presbyopia typically occurs around 40 years of age and affects approximately one-quarter of the global population. Up to October 2021, there were no approved pharmacotherapies for presbyopia, and common treatments, such as glasses, can have disadvantages for individuals' health-related quality of life. PURPOSE: This study aimed to document the experience of living with and managing presbyopia, identify perspectives on treatment options, and determine whether there is an unmet need in the treatment landscape. METHODS: Coded transcripts of concept elicitation (CE; n = 20) and cognitive debriefing (n = 20) interviews with presbyopic individuals, originally conducted for development of patient-reported outcome instruments, were reanalyzed to identify salient concepts describing participants' experiences with presbyopia treatments. Qualitative ranking exercises assessed participants' preferences for a potential pharmacotherapy vs. existing treatments. RESULTS: Because most concepts were identified with the CE interviews, data reflect CE findings unless otherwise noted. Average age across CE/cognitive debriefing interviews was 49.4 years; a vast majority of participants used glasses for presbyopia treatment. Four themes related to treatment with glasses were identified with the interviews: inconvenience during daily activities, negative physical sensations around the eyes/head, limitations, and undesirable impacts on daily life (e.g., psychosocial). Most commonly, participants reported inconveniences related to forgetting glasses and psychosocial impacts (e.g., feeling/looking older). Strained/tired eyes and limited ability to see at varying distances were also reported. Among participants with near-vision glasses who provided data, two-thirds expressed interest in alternative treatments. In addition, almost three-quarters of the participants ranked hypothetical eye drops as their first or second preferred option, vs. reading glasses, contact lenses, magnifying glasses, and surgery. CONCLUSIONS: This study explored the experience of living with and managing presbyopia and identified limitations and negative impacts of current treatments. Pharmacological development (e.g., eye drops) may fulfill an unmet need in the presbyopia treatment landscape.

Living with presbyopia: experiences from a virtual roundtable dialogue among impacted individuals and healthcare professionals.

BACKGROUND: Presbyopia is a common progressive vision disorder characterised by an inability to focus on near objects. The emergence of newer treatment options in addition to spectacles or contact lenses highlights the importance of assessing patient/user preferences. METHODS: People with presbyopia and healthcare professionals (HCPs) took part in a moderated, structured discussion of specific questions on a virtual advisory-board platform. The objective was to better understand unmet needs and the experience of living with the condition. Closed and open questions were included. RESULTS: Nine individuals (age 40 to 70 years) with presbyopia participated, from Australia, China, France, Italy, Ireland, Japan and the US. One ophthalmologist and one optometrist represented the perspective of HCPs. Over two weeks, 621 posts were entered on the platform. There was widespread agreement that the often stated association between age and presbyopia was unfortunate. Some participants had developed presbyopia at 30-45 years of age. What is more, the association with age was seen as implying a natural process, reducing the incentive to treat. Instead there was a call for an action-oriented view of presbyopia as a condition which may be effectively treated in the future. All participants experienced dealing with presbyopia as burdensome, affecting quality of life to varying degrees. When considering new treatments, convenience was the most important factor. The option to administer drops when needed was considered favourable, but short-acting treatments may not reduce inconvenience compared with spectacles. Participants viewed a therapy that targets the underlying cause of the condition favourably compared with symptomatic treatment. Side effects would severely reduce the appeal of drops. For clinical trials in presbyopia, patient-reported outcomes should be mandatory and need adequately to capture quality of life. Studies in presbyopia must be designed to minimise the inconvenience to participants in order to counter the risk of high drop-out rates. CONCLUSIONS: The interactive format provided insights into living with presbyopia, particularly the negative impact on quality of life, subjects' openness to new therapies, and the need to move away from considering the condition an unavoidable and intractable consequence of ageing.

The term presbyopia describes the difficulty to focus the eyes on things nearby, due to stiffening of the eye lens. The condition often considered something which worsens with increasing age. Many people cope with presbyopia by wearing reading glasses or bifocals, but alternative treatments are being developed. This publication reports from a moderated discussion among people with presbyopia and healthcare professionals specialising in eye health. People with presbyopia strongly felt that it should not be seen as an inevitable effect of middle age, but as something which may be treated medically. They felt that reading glasses, bifocals and monovision lenses were a daily burden and did not fit with how they wanted to live their lives. When discussing possible medical treatments, the option to use drops instead of glasses to improve eye sight appealed to the participants, particularly if the drops acted on the mechanism behind the stiffened lens with effect over many weeks or months. Convenience was the key benefit the participants would look for when considering a new treatment. Importantly, drops must not have any undesirable effects such as burning. The roundtable discussion showed the need for both healthcare professionals and those living with presbyopia to take the condition seriously with an an action-oriented view towards better therapies in the future.

Multifocal contact lens vision simulated with a clinical binocular simulator.

PURPOSE: The purpose of this study is to compare the binocular visual perception of participants wearing multifocal contact lenses and these same lens designs viewed through a temporal multiplexing visual simulator. METHODS: Visual performance and perceived visual quality at various distances were obtained in 37 participants wearing soft M-CLs and through the SimVis Gekko programmed with the same lenses. In a pilot study (n = 10) visual performance was measured in terms of LogMAR visual acuity (VA) at far (4 m), intermediate (64 cm) and near (40 cm) distances and through-focus VA (TFVA) curves with the simulated M-CLs. In the follow-up study (n = 27), LogMAR VA at far, intermediate and near distances were measured both with the actual and simulated M-CLs. Perceived visual quality was measured in both studies using the Multifocal Acceptance Score (MAS-2EV), and a Participants Reported Outcomes Vision questionnaire. Differences between the metrics obtained with simulated and actual lenses were obtained. RESULTS: Both actual and simulated M-CLs increased depth-of-focus by a similar amount. Mean LogMAR VA differences with actual and simulated M-CLs ranged between 4 and 6 letters (0.08 ± 0.01, 0.12 ± 0.01 and 0.10 ± 0.01, for far, intermediate and near distances, respectively). MAS-2EV average score differences with actual and simulated M-CLs ranged between -1.00 and + 4.25. Average MAS-2EV scores were not correlated significantly with VA. However, MAS-2EV (average and individual scores) were highly correlated to visual quality questionnaire responses (p < 0.005). CONCLUSIONS: A simultaneous vision simulator accurately represented vision with M-CLs both VA at various distances and perceived visual quality, as measured in a clinical setting. The MAS-2EV metric accurately captured participant reported outcomes of standard vision questionnaires. The combination of SimVis Gekko and MAS-2EV has the potential to largely reduce chair time in M-CLs fitting.

Exploring contact lens opportunities for patients above the age of 40 years.

PURPOSE: Contact lenses offer a good option for patients with presbyopia, especially with improved optical designs available in modern multifocal contact lenses. Due to the ageing population there is good opportunity to increase contact lens penetration by managing these patients better. However, multifocal contact lenses achieve low penetration in the market. METHODS: A questionnaire was administered to people aged above 40 years, to investigate their perceptions of contact lenses for presbyopia. Only people, with presbyopia, who were existing contact lens wearers or willing to try contact lenses were included. Participants were recruited from United Kingdom (UK), United States of America (USA), Netherlands, Germany, France, Spain and Italy. RESULTS: Data from 1540 participants above the age of 40 years was collected, 57.9% were females and 42.1% males. Overall, 50.8% of the participants wore contact lenses, but contact lens wear was less common amongst older participants. Some data supported earlier studies, such as 6.1% wore gas permeable lenses. However, only 25% of the contact lens wearers used multifocal contact lenses. The reasons the participants wanted to wear contact lenses were similar to younger patient such as sports or cosmesis reasons. Reasons why participants had dropped out of contact lenses included discomfort and dry eye related issues. Poor visual performance with contact lenses was a reason to dropout of contact lenses for the older participants. CONCLUSIONS: The study highlights some failings by eye care practitioners in the management of patients with presbyopia. It seems that patients of this age group are seeking suggestions and recommendations from their eye care practitioner including upgrading contact lenses and dual wear options. The day-to-day problems encountered by the contact lens wearers in this study seem to be, in the main, things that could be easily tackled by additional counselling and instruction from the eye care practitioners.

Visual performance with multifocal lenses in young adults and presbyopes.

A better understanding of visual performance with Multifocal Contact Lenses (MCLs) is essential, both in young eyes, where MCLs may be prescribed to control the progression of myopia wherein the MCLs optics interact with accommodation, and in presbyopes, where MCLs are increasingly used to compensate the lack of accommodation. In this study, we evaluated the through focus visual acuity (TFVA) with center-near MCLs of three additions (low, medium and high) and without an addition (NoLens) in 10 young adults and 5 presbyopes. We studied the effect of accommodation, age and pupil diameter (in cyclopleged subjects) on visual performance. The MCLs produced a small but consistent degradation at far (by 0.925 logMAR, averaged across eyes and conditions) and a consistent benefit at near in young subjects with paralyzed accommodation (by 1.025 logMAR), and in presbyopes with both paralyzed and natural accommodation (by 1.071 logMAR, on average). TFVA in young adults with NoLens and all MCLs showed statistically significant differences (Wilcoxan, p<0.01) between natural and paralyzed accommodation, but not in presbyopes with MCLs. In young adults, VA improved with increasing pupil diameter with the HighAdd MCL (0.08 logMAR shift from 3 to 5-mm pupil size). Visual imbalance (standard deviation of VA across distances) was reduced with MCLs, and decreased significantly with increasing near add. The lowest imbalance occurred in young adults under natural accommodation and was further reduced by 13.33% with MCLs with respect to the NoLens condition. Overall, the visual performance with MCLs in young adults exceeds that in presbyopes at all distances, and was better than 0.00 logMAR over the dioptric range tested. In conclusion, the center-near lenses do not degrade the near high contrast visual acuity significantly but maintains the far vision in young adults, and produce some visual benefit at near in presbyopes.

Testing the efficacy of vision training for presbyopia: alternating-distance training does not facilitate vision improvement compared to fixed-distance training.

PURPOSE: Current evidence demonstrates the effectiveness of vision training for presbyopia. We developed and examined a training program to test the effectiveness of alternating focal distances as a training method. METHODS: We devised a sharpness discrimination task, in which participants judged whether the stimulus was a sine- or square-wave grating, and tested in two training groups and one control group. In the alternating-distance training group (N = 8, age 49-64), participants had to alternate the fixation between a near- and far-screen. In the fixed-distance training group (N=8, age 47-65), participants fixated on the same-distance target for the whole block. Before and after the 20 training sessions, we measured the near- and far-visual acuity (VA) using the Landolt C and Early Treatment Diabetic Retinopathy Study (ETDRS) tasks and contrast sensitivity using the qCSF procedure. The control group (N=8, age 49-65) participated only in the pre- and post-tests. RESULTS: Both training groups showed a significant improvement between the pre- and post-tests in the Landolt C task, and the improvement sizes were not significantly different between the groups. In the ETDRS task, only the fixed-distance training group showed significant improvement, although there was no significant difference between the two groups. Neither group showed improvement in the contrast sensitivity task compared to the control group. CONCLUSION: The novel sharpness discrimination task can be an effective training method for presbyopia to prevent the deterioration of VA; however, contrary to popular belief, the effect of alternating-distance training was comparable to or even weaker than that of fixed-distance training.

Population-based assessment of prevalence of spectacle use and effective spectacle coverage for distance vision in Andhra Pradesh, India - Akividu Visual Impairment Study.

CLINICAL RELEVANCE: Effective spectacle coverage is a useful indicator to assess the coverage of refraction services in a given region. We found a low coverage in the Akividu region suggesting a need to develop effective refraction services. BACKGROUND: To assess the prevalence of spectacle use and effective spectacle coverage for distance vision among people aged 40 years and older in the Indian state of Andhra Pradesh. METHODS: A population-based cross-sectional survey was carried out in the Akividu region in West Godavari and Krishna districts. The study teams visited selected households and conducted eye examinations in the selected clusters. A structured questionnaire was used to collect information on spectacle use. 'Met Need' was defined as unaided VA worse than 6/12 but improved to 6/12 or better with their current spectacles. 'Unmet Need' was defined as unaided VA worse than 6/12 but improved to 6/12 with pinhole, among those not using spectacles. The 'Under-met Need' was defined as aided VA worse than 6/12 but improving with pinhole to 6/12 or better. Based on these definitions, Effective Refractive Error Coverage (e-REC) is calculated as: e-REC (%) s = ((met need)/(met need + under-met need + unmet need)) X100. RESULTS: Of 3,000 enumerated from 60 clusters, 2,587 (86.2%) participants were examined. The prevalence of current spectacle use was 43.1% (95% CI:41.2-45.0). The e-REC was 37.4%. It was also lower in men compared to women and among those without any education. Participants who had cataract surgery in either eye had similar e-REC compared to those who were not operated. CONCLUSION: Though spectacle use was found to be high, there is a still large unmet need for refractive correction for distance. Effective service delivery models to provide refraction and spectacle dispensing services are needed to achieve universal eye health coverage in the region.