Functional Presbyopia Research Articles

Understanding accommodative control in the clinic: Modeling latency and amplitude for uncorrected refractive error, presbyopia and cycloplegia.

Accommodation is the process of adjusting the eye's optical power so as to focus at different distances. Uncorrected refractive error and/or functional presbyopia mean that sharp focus may not be achievable for some distances, so observers experience sustained defocus. Here, we identify a problem with current models of accommodative control: They predict excessive internal responses to stimuli outside accommodative range, leading to unrealistic adaptation effects. Specifically, after prolonged exposure to stimuli outside range, current models predict long latencies in the accommodative response to stimuli within range, as well as unrealistic dynamics and amplitudes of accommodative vergence innervation driven by the accommodative neural controller. These behaviors are not observed empirically. To solve this issue, we propose that the input to blur-driven accommodation is not retinal defocus, but correctable defocus. Predictive models of accommodative control already estimate demand from sensed defocus, using a realistic "virtual plant" to estimate accommodation. Correctable defocus can be obtained by restricting this demand to values physically attainable by the eye. If we further postulate that correctable defocus is computed using an idealized virtual plant that retains a young accommodative range, we can explain why accommodative-convergence responses are observed for stimuli that are too near-but not too far-to focus on. We model cycloplegia as a change in gain, and postulate a form of neural myopia to explain the additional relaxation of accommodation often seen with cycloplegia. This model produces plausible predictions for the accommodative response and accommodative convergence signal in a wide range of clinically relevant situations.

Subjective Wellbeing, Work Performance and Lived Experience of Zanzibari Women Entrepreneurs with Uncorrected Functional Presbyopia: A Pre-Post Mixed-Methods Study

ABSTRACT Purpose Uncorrected presbyopia has been shown to reduce Zanzibari women’s quality of life. In this mixed-methods study, we examined the subjective wellbeing and self-reported work performance among older women entrepreneurs with functional presbyopia before and shortly after correction, and how poor vision at close distance affected their daily lives. Methods Women entrepreneurs underwent eye examination to identify those with uncorrected functional presbyopia. Their subjective wellbeing and work performance were both measured in Cantril’s ladder. Ready-made glasses were then provided and 30 minutes to an hour later, their subjective wellbeing and work performance was remeasured. Twenty women entrepreneurs were interviewed to understand their lived experience with uncorrected presbyopia. Results Two-hundred-seventeen women entrepreneurs were included in the survey (mean age 51.6 years, SD 8.64). Women entrepreneurs had a mean subjective wellbeing score of 3.32 (SD 1.10) pre-correction and 5.99 (SD 1.13) post-correction (p < .001), and a mean self-rated current work performance score of 4.62 (SD 1.36) before correction and 5.47 (SD 1.35) post-correction (p < .001). One-hundred-and-ninety (87.6%) and 121 women entrepreneurs (55.8%) rated their current subjective wellbeing and work performance scores < 5, respectively. Around 1/4 of women entrepreneurs reported having severe difficulties with near tasks. Conclusion Poor vision at a close distance caused by uncorrected functional presbyopia negatively affected economic, physical and psychosocial aspects of women entrepreneurs’ lives. Subjective wellbeing and self-reported work productivity scores improved significantly shortly after presbyopia was corrected. More research with longer follow-up is needed to understand the full benefits of correcting presbyopia.

PMD178 - GLOBAL BURDEN OF PRESBYOPIA: A SYSTEMATIC LITERATURE REVIEW

To conduct a systematic literature review to collate the published evidence on the burden (economic and humanistic) of presbyopia. Medline, Embase, and Cochrane databases were searched from the inception dates up to February 2018. Studies published in the English language reporting the humanistic and economic burden in presbyopic patients were included. We identified 29 published studies that met the inclusion criteria (22- humanistic burden; 7-economic burden). Published population based surveys and reviews report that uncorrected presbyopia when coexisting with far-sight refractive errors is associated with noticeable reduction in patients’ vision related quality of life (comorbidity adjusted utility of 0.62 in severe to 0.70 in moderate patients). Based on findings from a review study of multiple population based surveys, globally around 80% of the patients with uncorrected presbyopia reported functional visual impairment and reduction in vision related quality of life due to difficulty in performing near vision related tasks such as ability to read, write, threading needles, and usage of mobile devices. They also estimated that in 2005, globally, around 410 million people had functional presbyopia and report experiencing disability. Global loss of productivity from uncorrected and under-corrected presbyopia among people aged <50 years was estimated to be US $11 billion (0.016% of global GDP) in 2011 which increased up to US$ 25.4 billion if people aged <65 years were assumed to be productive. Uncorrected presbyopia could significantly affect patients’ vision related quality of life with difficulty in performing near vision related tasks in the majority of patients. In addition, un-/under-corrected presbyopia could lead to productivity loss in working age adults. Further studies are required to estimate the burden of post-operative presbyopia in cataract patients.

Prevalence and incidence of presbyopia in urban Southern China

AimsTo investigate the prevalence and incidence of presbyopia in an urban Chinese population.Methods1817 subjects aged ≥35 years were identified by random cluster sampling in Yuexiu District, Guangzhou, China, at baseline...

Magnitude, temporal trends, and projections of the global prevalence of blindness and distance and near vision impairment: a systematic review and meta-analysis.

Global and regional prevalence estimates for blindness and vision impairment are important for the development of public health policies. We aimed to provide global estimates, trends, and projections of global blindness and vision impairment. We did a systematic review and meta-analysis of population-based datasets relevant to global vision impairment and blindness that were published between 1980 and 2015. We fitted hierarchical models to estimate the prevalence (by age, country, and sex), in 2015, of mild visual impairment (presenting visual acuity worse than 6/12 to 6/18 inclusive), moderate to severe visual impairment (presenting visual acuity worse than 6/18 to 3/60 inclusive), blindness (presenting visual acuity worse than 3/60), and functional presbyopia (defined as presenting near vision worse than N6 or N8 at 40 cm when best-corrected distance visual acuity was better than 6/12). Globally, of the 7·33 billion people alive in 2015, an estimated 36·0 million (80% uncertainty interval [UI] 12·9-65·4) were blind (crude prevalence 0·48%; 80% UI 0·17-0·87; 56% female), 216·6 million (80% UI 98·5-359·1) people had moderate to severe visual impairment (2·95%, 80% UI 1·34-4·89; 55% female), and 188·5 million (80% UI 64·5-350·2) had mild visual impairment (2·57%, 80% UI 0·88-4·77; 54% female). Functional presbyopia affected an estimated 1094·7 million (80% UI 581·1-1686·5) people aged 35 years and older, with 666·7 million (80% UI 364·9-997·6) being aged 50 years or older. The estimated number of blind people increased by 17·6%, from 30·6 million (80% UI 9·9-57·3) in 1990 to 36·0 million (80% UI 12·9-65·4) in 2015. This change was attributable to three factors, namely an increase because of population growth (38·4%), population ageing after accounting for population growth (34·6%), and reduction in age-specific prevalence (-36·7%). The number of people with moderate and severe visual impairment also increased, from 159·9 million (80% UI 68·3-270·0) in 1990 to 216·6 million (80% UI 98·5-359·1) in 2015. There is an ongoing reduction in the age-standardised prevalence of blindness and visual impairment, yet the growth and ageing of the world's population is causing a substantial increase in number of people affected. These observations, plus a very large contribution from uncorrected presbyopia, highlight the need to scale up vision impairment alleviation efforts at all levels. Brien Holden Vision Institute.

The Global Burden of Potential Productivity Loss from Uncorrected Presbyopia

The onset of presbyopia in middle adulthood results in potential losses in productivity among otherwise healthy adults if uncorrected or undercorrected. The economic burden could be significant in lower-income countries, where up to 94% of cases may be uncorrected or undercorrected. This study estimates the global burden of potential productivity lost because of uncorrected functional presbyopia. Population data from the US Census Bureau were combined with the estimated presbyopia prevalence, age of onset, employment rate, gross domestic product (GDP) per capita in current US dollars, and near vision impairment disability weights from the Global Burden of Disease 2010 study to estimate the global loss of productivity from uncorrected and undercorrected presbyopia in each country in 2011. To allow comparison with earlier work, we also calculated the loss with the conservative assumption that the contribution to productivity extends only up to 50 years of age. The economic modeling did not require the use of subjects. We estimated the number of cases of uncorrected or undercorrected presbyopia in each country among the working-age population. The number of working-age cases was multiplied by the labor force participation rate, the employment rate, a disability weight, and the GDP per capita to estimate the potential loss of GDP due to presbyopia. The outcome being measured is the lost productivity in 2011 US dollars resulting from uncorrected or undercorrected presbyopia. There were an estimated 1.272 billion cases of presbyopia worldwide in 2011. A total of 244 million cases, uncorrected or undercorrected among people aged <50 years, were associated with a potential productivity loss of US $11.023 billion (0.016% of global GDP). If all those people aged <65 years are assumed to be productive, the potential productivity loss would be US $25.367 billion or 0.037% of global GDP. Correcting presbyopia to the level achieved in Europe would reduce the burden to US $1.390 billion (0.002% of global GDP). Even with conservative assumptions regarding the productive population, presbyopia is a significant burden on productivity, and correction would have a significant impact on productivity in lower-income countries.

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

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

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

To assess the prevalence of presbyopia, spectacles use and spectacle correction coverage for near vision among weaving communities in Prakasam district in the South Indian state of Andhra Pradesh. A population based cross sectional study was conducted among a population aged ≥40years. Distance visual acuity was assessed at 6m. Near vision was assessed using N notation charts at a fixed distance of 40cm. Presbyopia was defined as binocular unaided near vision <N8 and improving to ≥N8 with near addition lenses. Functional presbyopia was defined as presenting near vision <N8 and improving to ≥N8 with near addition lenses. A questionnaire was used to collect information on spectacles use. In order to calculate spectacle correction coverage for presbyopia, met presbyopia need was defined as the percentage of people who presented with presbyopia correction and achieved binocular N8 using it. Unmet presbyopia need was defined as the percentage of people who had either under corrected or uncorrected binocular near vision worse than N8 that would improve with correction to at least N8. Of 2848/3000 enumerated subjects (94.0%) participated. Four hundred individuals with distance visual impairment were excluded from the analysis. Among the remaining 2448 individuals, 46% were male and 49.1% had no formal education. The mean age among males was higher compared to females (p<0.01). Based on unaided near vision, the prevalence of presbyopia was 61.8% (95% CI: 59.9-63.7) and the prevalence of functional presbyopia was 35.1% (95% CI: 33.2-37.0). Using multivariable analysis, it was found that functional presbyopia was significantly associated with female gender, no education and lack of spectacle use. Spectacle correction coverage was 43.2%. Among the 781 individuals who had no correction at the time of examination, 122 (15.6%) subjects reported having used spectacles previously. The reasons for discontinuation of spectacles were discomfort with spectacles (n=57; 46.7%), damaged or lost spectacles (n=45; 36.9%), ability to see clearly even without spectacles (n=12; 9.8%) and other reasons (n=8; 6.6%). Although the prevalence of presbyopia (61.8%) was comparable with other studies, the prevalence of functional presbyopia (35.1%) was lower and linked with higher spectacle correction coverage (43.2%) in this weaving community. However, it still highlights a large unmet need and spectacle correction coverage that could be improved by the provision of good quality, affordable spectacles, which may also improve spectacles use.

Presbyopia in plateau state, Nigeria: A hospital study

Presbyopia is a refractive error (RE) that causes near visual impairment with advancing age. Uncorrected presbyopia significantly affects near vision-related quality of life of individuals who depend on near work for livelihood, be they literate or illiterate. This study is aimed at finding the prevalence of presbyopia in patients who presented with refractive error in Adoose specialist hospital, Jos. Materials and Methods: Records of all patients who presented at the hospital from 2000 to 2009 with symptoms of functional presbyopia, defined as requiring at least + 0.75 dioptre in order to read the N8 optotype at a distance of 40 cm in the patient's usual visual state were included in the study. The eye with the better presenting visual acuity was used for classifying the patients. Results: There were 912 patients with RE. Of these, there were 482 (52.9%) subjects whose visual acuities improved to N8 optotype at a distance of 40 cm with refraction.There were 265 (55%) males and 217 (45%) females. The mean age of patients at presentation was 47.8 ± 8.2 (range 35-80) years. Most of the patients (77.1%) complained of problems with near visual tasks. Seventy-five (15.7%) subjects presented with glasses of inappropriate corrections that was causing visual strains.Presbyopia showed a significant increase with increasing age. The power ranged from +0.75 to +4.0D (with a mean of 2.08). The most frequent power was +2.0D.The civil servants 257 (53.3%) formed the highest number of subjects seeking presbyopic correction.Plano-presbyopia was the commonest presentation at 51.6% and it showed a significant decrease with increasing age. This was followed by hypermetropia − presbyopia at 32.6% which increased with the increasing age. There were fewer subjects (15.8%) with myopia-presbyopia.Conclusion: This study has shown that presbyopia presents early and is a problem in our society. Economic consequences are likely to be considerable, as uncorrected presbyopia affects people in the working-age group.

Quality of Life and Near Vision Impairment Due to Functional Presbyopia among Rural Chinese Adults

To evaluate the impact of near-vision impairment on visual functioning and quality of life in a rural adult population in Shenyang, northern China. A population-based, cross-sectional study was conducted among persons aged 40+ years, during which functional presbyopia (correctable presenting near vision < 20/50 [N8] at 40 cm) was assessed. Near-vision-related quality of life and spectacle usage questionnaires were administered by trained interviewers to determine the degree of self-rated difficulty with near tasks. A total of 1008 respondents (91.5% of 1102 eligible persons) were examined, and 776 (78%) of completed the questionnaires (mean age, 57.0 ± 10.2 years; 63.3% women). Near-vision spectacle wearers obtained their spectacles primarily from markets (74.5%) and optical shops (21.7%), and only 1.14% from eye clinics. Among 538 (69.3%) persons with functional presbyopia, self-rated overall (distance and near) vision was worse (P < 0.001) and difficulty with activities of daily living greater (P < 0.001) than among nonpresbyopes. Odds of reporting any difficulty with daily tasks remained higher (OR = 2.32; P < 0.001) for presbyopes after adjustment for age, sex, education and distance vision. Compared to persons without presbyopia, presbyopic persons were more likely to report diminished accomplishment due to vision (P = 0.01, adjusted for age, sex, education, and distance vision.) Difficulties with activities of daily living and resulting social impediments are common due to presbyopia in this setting. Most spectacle wearers with presbyopia in rural China obtain near correction from sources that do not provide comprehensive vision care.

Presbyopia and Near-Vision Impairment in Rural Northern China

Presbyopia limits activities of daily living, but population-based data from rural China are scarce. A population-based, cross-sectional study was conducted in 2009 among all persons aged 40+ years in a rural area near Shenyang, China. Distance and near VA were measured using logMAR E charts. Individuals with pinhole-corrected distance vision ≥20/63 underwent detailed eye examination and near refraction. A total of 1008 (91.5%) respondents were examined (mean age, 58.4 ± 10.7 years for men, 56.8 ± 9.89 years for women). Women and older subjects were more likely to participate. The prevalence of functional presbyopia (near vision <20/50 [N8] improved by ≥1 line with correction) was 67.3% (95% confidence interval [CI], 64.30%-70.09%), increasing from 27.6% at 40 to 49 years of age to 81.8% at 60 to 69 years. Multivariate analysis showed that older age (P < 0.001), but not gender or education, was significantly associated with a higher risk of presbyopia. Self-reported presbyopic spectacle correction coverage was 51.5%. In multivariate logistic regression models, worse presenting near vision (P = 0.013) and higher required spherical equivalent power (P < 0.001) were associated with having correction, while age, gender, education, and distance vision were unassociated. Major barriers reported by persons without near correction included poor quality of available glasses (33.1%) and lack of awareness of the condition and its treatment (28.8%). Presbyopia is highly prevalent in rural China, and nearly half of affected persons have no access to correction. Interventions should focus on education and improvement in the quality of refractive services.

Change in function and spectacle-use 2 months after providing presbyopic spectacles in rural Tanzania

AimsTo examine near vision spectacle retention and use, and changes in self-reported and performance-based near vision, 2 months after the provision of near vision spectacles.MethodsWe conducted a 2-month follow-up of...

Uncorrected Refractive Errors in Presbyopes attending medical college eye OPD

The study was conducted to find out the prevalence of pre-existing uncorrected refractive error in presbyopes who attended the Eye O.P.D. in medical college of Bangalore (India). 100 presbyopes were selected according to inclusion criteria. Complete ophthalmic examination including visual acuity and objective & subjective refraction was performed. History of difficulty of vision was noted. Observations were tabulated and analyzed. 47 out of 100 presbyopes had pre-existing uncorrected refractive error. Most common complaint was difficulty of distance vision. 33 out of 47 had never used spectacles. Equal number of hyperopes and myopes were present. OBJECTIVE To find out the prevalence of uncorrected refractive errors in presbyopes attending Eye OPD in medical college in Bangalore INTRODUCTION Presbyopia is described as the condition wherein the eye exhibits a progressively diminished ability to focus on near objects with age. Thus there emerges the need of near vision corrective spectacles. The first symptoms present between the age of 40-50 years with difficulty in reading fine prints, in dim illumination, eyestrain after long reading hours and transient blur vision (1). 2 different definitions are cited in various studies. Functional presbyopia is defined as needing a significant optical correction added to the presenting distance refractive correction to achieve a near visual acuity criterion (more than or equal to 1 line of acuity improvement in one case, J1 print in another, and N8 print in the other) ( 2-4) . Objective presbyopia is defined as needing a significant optical correction (more than or equal to 1.00 D) added to the best distance optical correction to improve near vision to a near visual acuity criterion of N8 (5). The prevalence of presbyopia varies from region to region. In southern India, Nirmalan et al (5) found a prevalence of 55 per cent in people aged 30 years and older. Refractive errors affect a large proportion of the population worldwide, irrespective of age, sex and ethnicity. A significant number of these are never recognized and treated. These people in their presbyopic age present with uncorrected refractive errors. According to the Bulletin of the World Health Organization, in 2004, the number of people (above the age of 40 years) visually impaired from uncorrected refractive errors in India were almost 35 million (6). It was also shown that the coverage of refractive services in various regions of India ranges just between 40-55%. Uncorrected distance refractive error is the most common cause of vision impairment and the second most common cause of blindness in the world (6-9). This study is aims to find out the prevalence of pre-existing uncorrected refractive error in presbyopes attending Eye OPD in medical college in Bangalore.

Functional presbyopia in Kenya

Functional presbyopia in Kenya

Functional presbyopia in a rural Kenyan population: the unmet presbyopic need

Presbyopia is the most common reason for requiring spectacles in low-income regions, although the unmet need for presbyopic spectacles in these regions is very high. The aim of this study was to estimate the prevalence of presbyopia, and the functional impairment and spectacle use among persons with presbyopia in a rural Kenyan population. A cross-sectional study was carried out in the Rift Valley, Kenya. Clusters were selected through probability-proportionate to size sampling, and people aged >/=50 years within the clusters were identified through compact segment sampling. Within the context of this survey, 130 eligible participants were selected for interview and underwent near-vision testing. Functional presbyopia was defined as requiring at least +1.00 dioptre in order to read the N8 optotype at a distance of 40 cm in the participant's usual visual state. Participants were corrected to the nearest 0.25 dioptre in order to see N8. Unmet and met presbyopic need, and presbyopic correction coverage were calculated. Functional presbyopia was found in 111 participants (85.4%). Mean age was lower in those with presbyopia (64.1 years vs. 71.5 years, P = 0.004). Increasing degree of addition required to see N8 was significantly associated with increased difficulty with reading (P = 0.04), sewing (P = 0.03), recognizing small objects (P = 0.02) and harvesting grains (P = 0.05). Among participants with functional presbyopia, 5.4% wore reading glasses and 25.2% had prior contact with an eye care professional. The unmet presbyopic need was 80.0%, met presbyopic need was 5.4% and presbyopic correction coverage was 6.3%. Cost was cited as the main barrier to spectacle use in 62% of participants with presbyopia. In low-income regions, there is a high prevalence of uncorrected presbyopia, which is associated with near-vision functional impairment. Provision of spectacles for near vision remains a priority in low-income regions.