Impact of blindness, visual impairment and cataract surgery on quality of life and visual functioning among adults aged 40 years and above in Sri Lanka

Aims To assess associations of visual function (VF) and quality of life (QOL) by presenting visual acuity (PVA) and causes of blindness and visual impairment. Methods Multi-stage cluster random sampling was used to identify a nationally representative sample of persons aged ≥ 40 years in Sri Lanka. Previously validated VF and QOL measurement instruments were administered to participants who were blind or severely visually impaired due to cataract, or refractive errors, those with moderate severe visual impairment of any cause and a sample of those with normal/near normal vision (VA ≥6/12 in the better eye). Questionnaires were also administered to persons who had undergone cataract surgery in one or both eyes and had a post-operative vision ≥ 6/60. Results The Cronbach α coefficients showed that the VF and QOL subscales had satisfactory internal consistency and reliability. Mean VF/QOL scores of individuals who were blind (presenting VA < 3/60 in the better eye) were significantly lower and the maximal difficulty in performing VF tasks and QOL-related activities. Persons visually impaired from cataract had the greatest difficulty in performing VF activities and QOL domains on all the items in the VF and QOL questionnaires. Persons operated for cataract had much better VF/QOL outcomes compared to those who were visually impaired due to cataract. Conclusions VF and QOL self-reported questionnaires are very useful to monitor patient-reported functional benefit from blindness control interventions in low and middle- income countries like Sri Lanka

Prevalence of self-reported disability, activity limitation and social participation in Sri Lanka

Introduction The World Health Organization estimates that 15% of the global population has a disability. Available evidence from Sri Lanka shows variable estimates of the magnitude of disability. Objectives Determine the prevalence of self-reported disability in the adult population aged ≥18 years, and associated risk factors in a nationally representative sample in Sri Lanka. Methods The Washington Group short questionnaire was used to identify persons with self-reported disability. Data were collected from responsible adults aged ≥18 years in the selected households. A four point-scale: “no difficulty”, “some difficulty”, “a lot of difficulty” and “cannot do at all” was used. Individuals screening positive for disability were administered an additional questionnaire on activity limitations, social participation and their health and financial concerns. Results Overall 41.5% (4131) [95% CI: 40.5-42.4] reported functional difficulty in at least one domain. The prevalence of disability, i.e. a lot of difficulty or cannot do at all was 3.8% (382) [95% CI: 3.5 – 4.2], while the prevalence of “some functional difficulty” was 37.6% (3749) [95% CI: 36.7-38.6]. The prevalence of disability increased with age and was higher among females, urban residents, and those with lower education and socio-economic status. Minor degrees of functional difficulties were more common among older people, females and people with lower education. Conclusions The prevalence of disability and varying degrees of functional difficulty is high among the adult population of Sri Lanka. Evidence shows that a strategic plan is required to address the magnitude of disability and functional limitations in Sri Lanka

Prevalence and visual outcomes of cataract surgery and cataract surgical coverage in Sri Lanka: findings from the National Blindness and Visual Impairment Survey

Introduction Cataract surgical coverage and visual acuity outcomes are important population level indicators for monitoring access to and the quality of cataract surgery, allowing subgroups with poorer access to be identified. Data on these indicators are not available for Sri Lanka at national level. Objectives Determine cataract surgical coverage and the outcomes of cataract surgery in a nationally representative sample of adults aged ≥40 years. Methods Cluster random sampling with proportionate to size procedures was used. All participants were interviewed to obtain data on education level, movable assets, and the year and place of cataract surgery, if applicable. Presenting and best corrected visual acuities were measured. All participants underwent slit lamp examination, including a dilated examination of the fundus. Cataract surgical coverage was calculated at the person level vision of <3/30, <6/60 and <6/18. Outcomes of cataract surgery were categorized as good (6/18 or better), borderline (<6/18-6/60) or poor (<6/60). Results A total of 345 persons among the 5,779 participants who were examined had undergone cataract surgery in one or both eyes (486 eyes). Cataract surgical coverage, which was high overall 85.4% for vision <3/60; 79.1% for vision <6/60), was significantly higher in younger age groups (Odds Ratio [OR] 5.65, 95% confidence interval [CI] 1.42-22.52), those in urban areas (OR 2.8, 95% CI 1.01-7.74) those with higher socio-economic status (OR 6.0; 95% CI 1.96-18.4). Coverage ranged from 60% in Uva Province to 100% in Southern Province. 59.7% of eyes had good outcomes at presentation increasing to 75.1% with correction. Conclusions Cataract surgery indicators for Sri Lanka are good, being better than most other Asian countries. Services should target those living in underserved Provinces

Prevalence, causes and magnitude of functional low vision in Sri Lanka: results from a national population based survey

Introduction The following definition of functional low vision is used in surveys to estimate the need for low vision services: corrected visual acuity in the better eye of less than 6/18 down to and including light perception from causes not amenable to treatment. However, such data for Sri Lanka is lacking. Objectives To determine the prevalence, causes and magnitude of functional low vision in a nationally representative sample of adults aged 40 years and above in Sri Lanka. Methods Distance visual acuity was measured using a LogMAR E chart. If the acuity was less than 3/60 in either eye, the ability to see hand movements, count fingers or perceive light was assessed. All underwent autorefraction followed by subjective refraction and measurement of best corrected acuity if indicated. Participants with a presenting acuity of <6/12 in the better eye were examined in details and a cause of visual loss was assigned. Analysis included those who fulfilled the definition of functional low vision. Results Among those examined, 59 participants fulfilled the definition of functional low vision: prevalence 1.02% (95% confidence interval 0.77-1.31%). The commonest causes were complications of cataract surgery (42.4%), and posterior segment conditions (30.5%) principally and age related macular degeneration (5 cases) and other retinal conditions (11 cases). Based on these estimates, 77,600 adults in Sri Lanka may benefit from low vision services. Conclusions The prevalence of functional low vision is slightly lower than the prevalence of blindness from all causes. Complications of cataract surgery are potentially avoidable causes

Prevalence and types of refractive errors, and spectacle coverage in Sri Lankan adults: The Sri Lanka National survey of blindness and visual impairment

Introduction Uncorrected refractive errors are the commonest cause of visual impairment globally. Despite this, the proportion of affected individuals who wear spectacles can be low, particularly in low and middle- income countries. No data were available for Sri Lanka. Objectives To estimate the prevalence of refractive errors and investigate their risk factors among adults aged 40 years and above. Another purpose was to calculate spectacle coverage and identify subgroups with low coverage. Methods Cluster random sampling was used to obtain a nationally representative sample. Presenting distance visual acuity was measured using a logMAR chart, with distance spectacle correction if usually worn. All underwent autorefraction and an optician measured best-corrected visual acuity after subjective refraction. Participants who had undergone cataract surgery were excluded. Spectacle coverage was assessed amongst participants with a visual acuity of <6/12 in the better eye due to refractive error who attended the examination site with spectacles. Results 5,779/6,713 (86.1%) enumerated adults were examined; 5,179 had refraction data. 67% had a refractive error: hyperopia 49.6%; myopia 17.4%. Refractive errors increased with age. Being aged 60 years and above and Sinhala ethnic group were independent risk factors. Spectacle coverage was 17.7% overall, being lower in females and the non-literate. Based on the findings, 1.66 million adults require spectacles for distance correction. Conclusions Refractive errors are very common in Sri Lankan adults, and there is a large unmet need for spectacles. Affordable services for refractive errors need to be scaled up, focusing on the most underserved subgroups in the population

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

X-ray emission from the Sombrero galaxy: discrete sources

We present a study of discrete X-ray sources in and around the bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival Chandra observations with a total exposure of ~200 ks. With a detection limit of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30 kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray binaries (LMXBs). We quantify the differential luminosity functions (LFs) for both the detected GC and field LMXBs, whose power-low indices (~1.1 for the GC-LF and ~1.6 for field-LF) are consistent with previous studies for elliptical galaxies. With precise sky positions of the GCs without a detected X-ray source, we further quantify, through a fluctuation analysis, the GC LF at fainter luminosities down to 1E35 erg/s. The derived index rules out a faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent findings in several elliptical galaxies and the bulge of M31. On the other hand, the 2-6 keV unresolved emission places a tight constraint on the field LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101 sources in the halo of Sombrero. The presence of these sources cannot be interpreted as galactic LMXBs whose spatial distribution empirically follows the starlight. Their number is also higher than the expected number of cosmic AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray surveys. We suggest that either the cosmic X-ray background is unusually high in the direction of Sombrero, or a distinct population of X-ray sources is present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

The azimuthal anisotropy of charged particles in PbPb collisions at nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS detector at the LHC over an extended transverse momentum (pt) range up to approximately 60 GeV. The data cover both the low-pt region associated with hydrodynamic flow phenomena and the high-pt region where the anisotropies may reflect the path-length dependence of parton energy loss in the created medium. The anisotropy parameter (v2) of the particles is extracted by correlating charged tracks with respect to the event-plane reconstructed by using the energy deposited in forward-angle calorimeters. For the six bins of collision centrality studied, spanning the range of 0-60% most-central events, the observed v2 values are found to first increase with pt, reaching a maximum around pt = 3 GeV, and then to gradually decrease to almost zero, with the decline persisting up to at least pt = 40 GeV over the full centrality range measured.Comment: Replaced with published version. Added journal reference and DO

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns