Search

PRECIS In this study, huge time delay was observed between first primary congenital glaucoma (PCG) symptom recognition by parents to ophthalmological diagnosis and this delay was unchanged over time. Bilateral affliction and mean presenting intraocular pressure (IOP) remained unaltered. PURPOSE To compare the trends in presentation of patients with PCG over 3 different time periods at 10-year intervals (1998, 2008, and 2018) managed by a single surgeon at one of the largest tertiary eye care centers in South India. METHODS Retrospective analysis of 313 eyes of 172 patients diagnosed to have PCG and treated at the L V Prasad Eye Institute (LVPEI) between January and December of the 3 specified years. Data collected included age at symptom recognition and at presentation, sex, affected eye, signs and symptoms, time between onset of symptoms and diagnosis (diagnostic delay), corneal clarity, and IOP. RESULTS Of the 172 patients, 48 (27.9%), 76 (44.2%), and 48 (27.9%) belonged to 1998, 2008, and 2018, respectively. Bilateral affliction (79% to 84%) was common and there was no sex predilection. The median age at recognition of first symptoms by caregivers/parents was 1 day (interquartile range, 1 to 30), and at diagnosis was 120 days (interquartile range, 30 to 378). Overall, presentation to LVPEI was delayed by >3 months in 80 (46.5%) children, and there was no statistically significant difference in the duration of delay over time (P=0.13). There was no significant difference in the mean presenting IOP over time (P>0.05). CONCLUSIONS We provide unique single center-based information of trends in the presentation of patients with PCG over 3 decades. Diagnostic delay was common, and a large number of characteristics of patients with PCG in South India have remained unchanged, particularly, age at onset and at diagnosis and laterality.

Purpose: The COVID-19 outbreak has adversely impacted all societal domains, including education. Home confinement, school closures, and distance learning impacted children, teachers, and parents’ lives worldwide. In this study, we aimed to examine the impact of COVID-19 lockdown on the lives, including education, of school-age children with vision impairment (VI) and their parents in India.\ud \ud Methods: Primary and secondary school children with VI were recruited from the Institute for Vision Rehabilitation, L V Prasad Eye Institute, Hyderabad, India. A qualitative research methodology, utilising a self-constructed questionnaire with open and closed questions and stem and leaf design was employed to explore the experiences of school closure and its impact on education, and attending online classes during the COVID-19 lockdown. Textual data from responses to the questions were analysed using content analysis to identify themes pertinent to the cohort studied.\ud \ud Results: Forty-eight child-parent dyads were included. Median age of children was 10 years (range, 7-19 years) and 60% were male. Inherited retinal disorders were the major cause of VI (40%). Best-spectacle corrected visual acuity (better eye) ranged from 6/12 (0.3 logMAR) to 6/750 (2.09 logMAR). Six major themes were identified: (1) accessibility of technology (online learning and technology); (2) parental beliefs/concerns (harmful effects of technology, prioritization of normally sighted children, online classes considered a distraction); (3) support (peers, parents, teachers, private tuition); (4) socialization and physical activity, (5) socioeconomic status, and (6) near vision. \ud \ud Conclusions: Our study provides an understanding of the adverse impact of the lockdown on the lives of children with VI and their parents, especially related to education in India. The study identified critical factors that affect online learning and the participation of children with VI in these sessions. Policy makers and educators should implement effective measures for supporting online classes.

PURPOSE To evaluate the long-term visual and surgical outcomes, and associated risk factors for poor outcomes in patients with primary congenital glaucoma (PCG). METHODS Retrospective review of medical records of children who underwent combined trabeculotomy-trabeculectomy (CTT) without mitomycin-C as the first surgical procedure by a single surgeon between January 1990 and December 2010. Success was defined as intraocular pressure (IOP)

Purpose The Caregiver's Congenital Glaucoma QoL (CarCGQoL) questionnaire was proposed as a measure of QoL of caregivers with children with primary congenital glaucoma (PCG). Support for its psychometric properties among other diagnostic groups is required for scores to be interpreted in the same manner across groups. Therefore we investigated the measurement properties and cross-diagnostic validity of the CarCGQoL questionnaire among caregivers of children with congenital cataract, retinopathy of prematurity (ROP), and blinding corneal disorders. Methods Eight hundred ninety-one caregivers (mean age, 28.3 years; 76% mothers) of children with congenital cataract (n = 407), ROP (n = 272), and blinding corneal disorders (n = 212) completed the CarCGQoL questionnaire. Rasch analysis was used to investigate the psychometric properties. Unidimensionality (by principal components analysis of residuals, PCA) was examined for each group and for pooled sample. Differential item functioning (DIF) was investigated to explore whether bias in responses to the questionnaire existed for certain subgroups as compared to the reference group (PCG). Results Across groups, six items necessitated removal because of misfit (two common and four uncommon), after which three different versions of the questionnaire emerged. Measurement precision was adequate for each group and for the pooled sample (0.80). Unidimensionality was observed, albeit with some DIF. Regardless of the level of QoL, caregivers in the pooled sample were more likely to endorse two items reflecting ability to face child's disease, and interest to pursue leisure activity, as compared with caregivers of children with PCG. Conclusions Care must be taken when data from the CarCGQoL questionnaire from different pediatric ocular conditions are pooled, given the presence of DIF between the reference group (PCG) and the pooled sample. Translational relevance When evaluating the impact of interventions on the caregiver's QoL using the CarCGQoL questionnaire in a pooled sample of pediatric ocular conditions, cross-diagnostic DIF must be taken into account.

Purpose Provide item calibrations estimated for the Impact of Vision Impairment (IVI) questionnaire by pooling data from several studies of people with vision impairment (VI) representing a variety of countries and causes of VI. Methods Eight data sets from six principal investigators representing responses to IVI items from 2867 VI patients were pooled for analysis. Eligible patients were 18 years or older and from Australia, India, and the United States. Rasch analysis, using the Andrich Rating Scale Model (Winsteps version 3.65), was performed on preintervention IVI responses to estimate item and person measures, reliability coefficients, and response category thresholds. Differential item functioning (DIF) analysis and analysis of variance (ANOVA) were used to examine the effects different data sets and covariates on item estimates. Results Patient age range was 18 to 103 years (median 62 years); 55% were male. Visual acuity ranged from 20/20 to no light perception and primary diagnosis was macular degeneration in 29% of patients. Item measure estimates showed good separation reliability (R2 = 0.99). DIF magnitude did not preclude use of all IVI-28 data. ANOVA showed VA (P < 0.001) and gender (P < 0.002) were predictors of visual ability. Conclusions Analysis from pooled data support the provision of calibrated IVI item measures for researchers and clinicians to use, thus better enabling direct comparisons of patients with VI. Translational Relevance Validity testing of the IVI show that we can combine disparate data sets of patient responses to calibrate item measures and response category thresholds, and provide to others for use in comparing patients across clinical trials and on an individual basis.

SIGNIFICANCE Mobile devices such as tablet computers have become widely available as mainstream devices and are also used in some schools, but there is an absence of robust information regarding the efficacy of any optical/electronic low vision device or tablet computer in supporting education of young people with low vision. PURPOSE A randomized controlled trial (RCT) is needed to measure the impact of tablet computers on education, specifically on independent access to educational material, in children and young people with low vision. We conducted a pilot RCT to determine the feasibility of conducting a full-scale trial. METHODS This was a randomized multicenter pilot trial across two sites in the United Kingdom and one site in India. Forty children and young people aged 10 to 18 years with low vision (best-corrected visual acuity for distance between

PURPOSE: To evaluate the health-related quality of life (HRQoL) of children operated for primary congenital glaucoma (PCG) using the Kidscreen-27 questionnaire. METHODS: A total of 121 children (mean age, 11.8 years; SD, 2.8 years; 51% males) with unilateral or bilateral PCG who underwent glaucoma surgery in infancy (mean duration since surgery, 10.2 years; [SD] 4.2 years) by a single surgeon at a tertiary eye care centre were administered the Kidscreen-27 questionnaire (self-or interviewer administered in a face-to-face interview) during their routine follow-up visit. We investigated the measurement properties of Kidscreen-27 questionnaire using Rasch analysis and generated interval-level estimates of HRQoL. The main outcome measure was HRQoL (i.e., Rasch-derived Kidscreen score). Multivariable linear regression analyses assessed the influence of socio-demographic and clinical variables on the HRQoL of children with PCG. RESULTS: Majority (83%) of the children had bilateral PCG and congenital type of the disease (79%). Mean presenting acuity (logMAR) in the better eye was 0.32 (SD, 0.36; median, 0.18). Rasch analysis of Kidscreen-27 questionnaire indicated need for minor modifications following which a psychometrically robust unidimensional 23-item Kidscreen questionnaire emerged. In multivariable model, age of the child was independently associated with a 32% (β = −0.24 [95% CI, −0.11, −0.36]) increase in the HRQoL score. CONCLUSIONS: Despite undergoing successful glaucoma surgery, children with PCG reported reduced HRQoL. Younger children with PCG are more likely to experience this lowered HRQoL and ophthalmologists will need to be alert to this. Efforts must be made to improve the HRQoL of children with PCG.

Purpose We developed and validated an instrument to measure the quality of life (QoL) of caregivers of children with primary congenital glaucoma (PCG): the Caregiver's Congenital Glaucoma Quality of Life (CarCGQoL) questionnaire. Methods A total of 70 caregivers of children with PCG under follow-up at a tertiary eye care center in India participated in a series of focus groups, and pre- and pilot testing phases in the development of the 45-item CarCGQoL questionnaire. Subsequently, this instrument was administered to 111 caregivers of children with PCG awaiting glaucoma surgery. Response to each item was rated on a four-category scale. Rasch analysis was used to validate the instrument's psychometric properties, such as unidimensionality (by principal components analysis [PCA] of residuals), item fit to model, measurement precision (by person separation [PS]), response category performance, differential item functioning (DIF), and targeting of items to participant's QoL. Results Categories required reorganization resulting in a shortened rating scale of 3 categories. The instrument showed misfit to the Rasch model and lacked unidimensionality. Deleting 15 items (obtained through PCA of residuals) restored unidimensionality, but additional items misfit, necessitating item reduction. In addition, 2 items showed DIF and were deleted. Finally, a 20-item CarCGQoL instrument showed good fit and unidimensionality. Targeting was good (0.69 logits) and PS was 2.51, indicating good measurement precision. Conclusions We have developed a psychometrically robust 20-item caregiver derived questionnaire, the CarCGQoL, that is a valid and reliable measure of QoL of caregivers of children with PCG. Given its brevity, it is quick and easy to administer in the clinic, and has potential for use as an outcome measure in clinical trials of treatment of PCG.

Introduction Low vision and blindness adversely affect education and independence of children and young people. New ‘assistive’ technologies such as tablet computers can display text in enlarged font, read text out to the user, allow speech input and conversion into typed text, offer document and spreadsheet processing and give access to wide sources of information such as the internet. Research on these devices in low vision has been limited to case series. Methods and analysis We will carry out a pilot randomised controlled trial (RCT) to assess the feasibility of a full RCT of assistive technologies for children/young people with low vision. We will recruit 40 students age 10–18 years in India and the UK, whom we will randomise 1:1 into two parallel groups. The active intervention will be Apple iPads; the control arm will be the local standard low-vision aid care. Primary outcomes will be acceptance/usage, accessibility of the device and trial feasibility measures (time to recruit children, lost to follow-up). Exploratory outcomes will be validated measures of vision-related quality of life for children/young people as well as validated measures of reading and educational outcomes. In addition, we will carry out semistructured interviews with the participants and their teachers. Ethics and dissemination NRES reference 15/NS/0068; dissemination is planned via healthcare and education sector conferences and publications, as well as via patient support organisations. Trial registration number NCT02798848; IRAS ID 179658, UCL reference 15/0570.

To examine the psychometric characteristics of the World Health Organization Quality of Life instrument—modified Indian version (modified WHOQOL) and its subscales in adults with visual impairment (VI) using Rasch analysis. Cross-sectional data were of people aged ≥40 years with VI (n = 1,333) who responded to the modified WHOQOL in the Andhra Pradesh Eye Disease Study, India. Rasch analysis was used to explore the instrument and its subscales for key indices such as measurement precision by person separation reliability, PSR (i.e., discrimination between strata of participants’ health-related QOL [HRQOL], recommended minimum value 0.8), unidimensionality (i.e., measurement of a single construct), and targeting (i.e., matching of item difficulty to participants’ HRQOL). Rasch-guided iterative approach including category re-organization to enable threshold ordering and item deletion to overcome multidimensionality resulted in a unidimensional 9-item WHOQOL and a 6-item level of independence (LOI) subscale with adequate PSR (0.81 and 0.82, respectively). Targeting was sub-optimal for both (−1.58 logits for WHOQOL and −2.55 logits for the subscale). Remaining subscales were dysfunctional. The WHOQOL and LOI subscale can be improved and shortened, and the Rasch-revised versions are likely to assess the HROQL of VI patients best because of their brevity, reliability, and unidimensionality.

Purpose We assess parent-child agreement regarding child's health-related quality of life (HRQoL) in children operated for congenital glaucoma (CG). Methods A total of 121 children aged 8 to 18 years (mean age, 11.8 years) operated for CG (mean duration since surgery, 10.2 years) and their parents (mean age, 36.5 years) completed the child and parent versions of the Kidscreen-27 questionnaire, respectively. Psychometric properties of Kidscreen-27 were assessed using Rasch analysis, and child-parent agreement regarding child's HRQoL was investigated using the Bland-Altman limits of agreement (LoA) method. Results Minor modifications in the rating scale and deletion of few misfitting items resulted in a psychometrically robust Kidscreen-23 questionnaire. Average parental HRQoL score was higher than the child's own ratings, with a significant difference between their scores (mean ± standard deviation [SD] difference = 0.53 ± 2.58 logits, P = 0.02; lower LoA [95% CI], -4.52 [-5.31 to -3.72] and upper LoA [95% CI], 5.58 [4.79-6.38]). The range of child-parent agreement was wide and bidirectional, with parents tending to underestimate and overestimate their child's HRQoL. Younger children and girls showed greater discordance in their HRQoL with parental reports than adolescents and boys, respectively. Conclusions Discordance between CG child's self-report of HRQoL and parent's report indicate that both groups perceive the broader impact of living with CG very differently. Translational relevance The HRQoL as reported by the child with CG and by his/her parent should be viewed as being complementary, rather than interchangeable. Both assessments should be taken into account in clinical practice and research studies.

Purpose: The Impact of Cataract Surgery (ICS) questionnaire was designed to assess cataract surgery outcomes. The aim of this study was to describe the psychometric properties of the ICS questionnaire using the Rasch model in a cataract population. Methods: Ninety-one patients waiting to undergo cataract surgery in the first or second eye at the Flinders Medical Centre, Adelaide, South Australia self-administered the four-item ICS questionnaire. Rasch analysis was performed to assess behaviour of response categories, ability to differentiate between participants’ visual abilities (person separation; minimum acceptable 2.0), if items measure a single underlying construct [i.e. unidimensionality assessed by fit statistics and further by principal components analysis (PCA)] and matching of item difficulty to participant ability (targeting; ideal

PurPose: The Adaptation to Age-related Vision Loss (AVL) scale was developed to measure the adjustment of older adults who are adapting to late-life vision loss. The purpose of this study was to assess whether the AVL scale satisfies the Rasch model in a cataract population. Methods: The 24-item AVL scale (18 negatively and 6 positively coded) was mailed to 436 cataract patients for self-administration whilst they were on the waiting list for cataract surgery at the Flinders Eye Centre, Adelaide, South Australia. Rasch analysis was performed to determine whether the items were measuring a single construct (unidimensionality) as examined with fit statistics and principal components analysis (PCA) of the residuals. The ability of the scale to distinguish between the levels of adaptation of the participants (person separation) was investigated, with a value ≥ 2.0 established as the minimum acceptable. results: The AVL scale was unable to differentiate sufficiently between participants’ levels of adaptation, indicating poor person separation. One item did not fit the construct, causing misfit. Furthermore, the five positively worded items did not appear either to measure the same construct as other items, resulting in lack of unidimensionality evidenced by PCA. Following the deletion of these items, the AVL scale was one-dimensional but a single item continued to misfit, so it had to be deleted, resulting in an 18-item AVL scale. Even so, the discriminating abilities of the scale continued to be poor. ConClusions: The AVL scale is not an appropriate measure of adaptation to vision loss in a cataract population. (J Optom 2009;2:142-147 ©2009 Spanish Council of Optometry)

PURPOSE To evaluate the outcomes of multidisciplinary low vision rehabilitation (LVR) in adults with low vision (LV) in India using the Veterans Affairs Low Vision Visual Functioning Questionnaire (VA LV VFQ-48) and the Impact of Vision Impairment (IVI) questionnaire. METHODS Consecutive adults with LV referred for the first time to the Centre for Sight Enhancement were administered the 28-item IVI and VA LV VFQ-48 before and after LVR (4 months). Rasch-scaled scores were generated for the IVI and the VA LV VFQ-48 along with each of their subscales at both the time points. Effect size (ES) was calculated using Cohen's d coefficient. RESULTS Two hundred fifty-five patients completed the LVR program. Following LVR, the linear measures revealed significant improvements in vision-related quality of life (VRQoL) using the IVI at follow-up (P < 0.0001), with large ES for reading and accessing information (ES = 1.0) and relatively moderate ES for overall IVI (ES = 0.63) and mobility subscale (ES = 0.53). No significant improvement was found on emotional well-being subscale (ES = 0.18; P = 0.06). Similarly, significant improvements in VRQoL (P < 0.0001) were found for the VA LV VFQ-48 at follow-up, albeit moderate ES for the overall visual ability (ES = -0.67) and its subscales (reading [ES = -0.72], mobility [ES = -0.45], visual information [ES = -0.47), visual motor [ES = -0.54]). CONCLUSIONS Regardless of the instrument used for assessment, our multidisciplinary LVR program resulted in statistically significant improvements in visual functioning and VRQoL of those adults with LV deemed appropriate for intervention (dropout rates were high); however, the improvements were modest, and the clinical relevance of these small improvements may be limited. Nonetheless, further studies should attempt to increase the completion rates in order to draw strong inferences.

Purpose The aim of the study was (1) to determine the need for spectacles in children in Southern India with coloboma, microphthalmos and microcornea, (2) to describe their refractive errors and (3) to assess their needs for low vision aids (LVAs). Methods Children with congenital eye anomalies were recruited from special education for the blind, schools for the mentally handicapped, community-based rehabilitation programmes and hospital records in Andhra Pradesh, India. All those with at least light perception vision (PU in one eye and who had navigational vision were refracted. Those whose distance vision in their better eye improved with refraction were prescribed spectacles. Those unable to read NI0 were assessed for LVAs for near. Those with distance visual acuity of < 6/18 in the better eye were assessed for telescopes to aid distance vision. Results Ninety-nine children with coloboma, microcornea or microphthalmos had functional vision. Eight unilateral cases were excluded. Ninety-one bilateral cases were refracted and assessed for LVAs. The vision in 52 children (57%) improved in the better- seeing eye by 1 or more lines of Snellen acuity with spectacles. Spectacles were prescribed most frequently for myopia associated with choroidal coloboma. After refraction, all 19 children with a visual acuity of 6/18 or better could read NI0, and 43 of the 72 children (60%) with a visual acuity of

Purpose To determine the visual success outcomes following treatment in an urban private eye hospital in India. Methods A retrospective survey was done of 4122 consecutive files of fee-paying patients admitted to a private eye hospital in Hyderabad during a 3-month period in 1996. Data obtained a minimum of 4 months after completion of treatment included age, sex, diagnosis and distance visual acuity in the best eye. Results After completion of treatment 86.5% of patients had normal vision, 10.9% had low vision and 2.5% were blind. Of the people with low vision or blindness after treatment, 81.7% had a best corrected visual acuity of between 6/18 and 6/60. The 4 most common causes of low vision after treatment were unoperated cataract (20.4%), glaucoma (13.3%), diabetic retinopathy (12.4%) and retinitis pigmentosa (10.2%). Conclusion The visual success rates in an urban Indian private eye hospital appear high with nearly 90% of patients achieving normal vision after the completion of treatment.

We determined if the Impact of Vision Impairment (IVI) is a valid questionnaire to measure the vision-related quality of life (VRQoL) in keratoconus patients, and investigated if the VRQoL varied with disease severity in this sample.WE RECRUITED 160 CONSECUTIVE BILATERAL KERATOCONUS PATIENTS (MEAN AGE 23.3 YEARS, 63% MALE) FROM AN INDIAN TERTIARY EYE CARE CENTER. PARTICIPANTS UNDERWENT A CLINICAL EXAMINATION AND COMPLETED THE IVI. PARTICIPANTS WERE DIVIDED INTO THREE GROUPS BASED ON THE AVERAGE OF THE STEEP KERATOMETRY (K) READINGS: mild (average Sim K45 diopters [D]), moderate (average Sim K 45-52 D), and severe (average Sim K52 D). Rasch analysis was used to validate the IVI and the VRQoL scores thus obtained were compared across the disease groups.THE MAJORITY (63%) OF PATIENTS HAD SEVERE, WHILE THE REMAINDER (37%) HAD MODERATE KERATOCONUS. RASCH ANALYSIS DEMONSTRATED THE VALIDITY OF THE IVI TO ASSESS VRQOL THROUGH TWO SUBSCALES: vision-specific functioning (VF) and emotional well-being (EWB). There was no significant difference in VF (mean change -0.16, P = 0.55) and EWB scores (mean change -0.32, P = 0.23) between moderate and severe keratoconus groups.The revised IVI subscales have interval-level measurement properties, which support their suitability to measure VRQoL in this keratoconus sample. Patients with moderate or severe keratoconus had similar, but higher VRQoL scores as assessed by the revised IVI subscales, indicating lack of impact of the disease on their VRQoL. However, this does not exclude the possibility of finding an impact in other populations.

PURPOSE To evaluate the impact of glaucoma on visual functioning in Indians. METHODS Patients attending the glaucoma service who had undergone a comprehensive glaucoma evaluation were recruited. Better mean deviation (MD, using Humphrey Field Analyzer program 24-2) between two eyes was used to classify participants into mild, moderate, and severe visual field (VF) loss groups. Participants were administered the Glaucoma Quality of Life-15 (GQL-15) questionnaire. Rasch analysis was used to validate the GQL-15 and its four subscales. Linear regression was used to determine associations between GQL-15 scores and VF loss after adjusting for sociodemographic variables. RESULTS A total of 198 patients (mean age ± SD, 59.8 ± 12.3 years; 67% male) were recruited. Participants with severe VF loss (39%) followed by mild loss (35%) comprised the largest group. Rasch analysis resulted in a 10-item reliable and valid questionnaire: the Glaucoma Activity Limitation-10 (GAL-10). Although a single subscale, "peripheral vision," met requirements of the Rasch model, it could not be preserved in the GAL-10. In multivariate analyses, the middle-income group (compared with higher income) and severe VF-loss (compared with mild VF-loss) participants reported significantly poorer functioning on GAL-10 ([β = 0.84; 95% confidence interval (CI), 0.16-1.52; P = 0.02] and [β = 1.19; 95% CI, 0.61-1.78; P < 0.000], respectively). None of these associations were, however, clinically significant. CONCLUSIONS Glaucoma patients in India, especially those with severe VF loss, face significant challenges in performing daily tasks and in mobility. It is important to prevent progression such that activity limitation is minimized in glaucoma patients.

A critical component that influences the measurement properties of a patient-reported outcome (PRO) instrument is the rating scale. Yet, there is a lack of general consensus regarding optimal rating scale format, including aspects of question structure, the number and the labels of response categories. This study aims to explore the characteristics of rating scales that function well and those that do not, and thereby develop guidelines for formulating rating scales. Methods: Seventeen existing PROs designed to measure vision-related quality of life dimensions were mailed for self-administration, in sets of 10, to patients who were on a waiting list for cataract extraction. These PROs included questions with ratings of difficulty, frequency, severity, and global ratings. Using Rasch analysis, performance of rating scales were assessed by examining hierarchical ordering (indicating categories are distinct from each other and follow a logical transition from lower to higher value), evenness (indicating relative utilization of categories), and range (indicating coverage of the attribute by the rating scale). Results: The rating scales with complicated question format, a large number of response categories, or unlabelled categories, tended to be dysfunctional. Rating scales with five or fewer response categories tended to be functional. Most of the rating scales measuring difficulty performed well. The rating scales measuring frequency and severity demonstrated hierarchical ordering but the categories lacked even utilization. Conclusion: Developers of PRO instruments should use a simple question format, fewer (four to five) and labelled response categories., This work was supported in part by National Health and Medical Research Council (Canberra, Australia) Centre of Clinical Research Excellence Grant 264620. Konrad Pesudovs and Ecosse Lamoureux are supported by National Health and Medical Research Council (Canberra, Australia) Career Development Awards 426765 and 529902, respectively.

PURPOSE Both the long form visual functioning scale (LFVFS(39)) and visual functioning scale (VFS) are measures of visual functioning (VF) that represent the Rasch-scaled versions of the NEI-VFQ(39) and the Indian vision function questionnaire (IND-VFQ), respectively. The objectives of this study were to investigate if the 15-item LFVFS(39) and 13-item VFS of the IND-VFQ meet the assumptions of the Rasch model and measure the same construct, VF, in an Indian visually impaired (VI) population. METHODS Data from 120 VI adults administered both instruments concurrently, were fitted to the Rasch measurement model to demonstrate that each instrument satisfies the assumptions of the model (including unidimensionality by principal components analysis); and both instruments can be cocalibrated onto a single underlying continuum of VF. RESULTS Both instruments required category reorganization for optimal rating scale functioning and possessed similar measurement precision (person separation = 2.76). Separate analysis of each instrument (eigenvalues, 2.3 and 1.9 for LFVFS(39) and VFS of IND-VFQ, respectively) and the pooled 28-item analyses (eigenvalue, 2.8) satisfied the assumptions of the Rasch model, including unidimensionality. Furthermore, all items fit in the separate and pooled analyses. Separate item and person measures for each instrument correlated strongly with estimates from the pooled data (r > 0.9 for all, P < 0.0001). CONCLUSIONS; Both the LFVFS(39) and VFS of the IND-VFQ measure the same construct, VF, and with equal measurement precision in an Indian VI population. Both instruments can be calibrated onto a single metric, thereby, enabling a comparison of their measurement range of VF.

Purpose: To investigate the effect of rating scale designs (question formats and response categories) on item difficulty calibrations and assess the impact that rating scale differences have on overall vision-related activity limitation (VRAL) scores. Methods: Sixteen existing patient-reported outcome instruments (PROs) suitable for cataract assessment, with different rating scales, were self-administered by patients on a cataract surgery waiting list. A total of 226 VRAL items from these PROs in their native rating scales were included in an item bank and calibrated using Rasch analysis. Fifteen item/content areas (e.g., reading newspapers) appearing in at least three different PROs were identified. Within each content area, item calibrations were compared and their range calculated. Similarly, five PROs having at least three items in common with the Visual Function (VF-14) were compared in terms of average item measures. Results: A total of 614 patients (mean age ± SD, 74.1 ± 9.4 years) participated. Items with the same content varied in their calibration by as much as two logits; “reading the small print” had the largest range (1.99 logits) followed by “watching TV” (1.60). Compared with the VF-14 (0.00 logits), the rating scale of the Visual Disability Assessment (1.13 logits) produced the most difficult items and the Cataract Symptom Scale (0.24 logits) produced the least difficult items. The VRAL item bank was suboptimally targeted to the ability level of the participants (2.00 logits). Conclusions: Rating scale designs have a significant effect on item calibrations. Therefore, constructing item banks from existing items in their native formats carries risks to face validity and transmission of problems inherent in existing instruments, such as poor targeting. Refereed/Peer-reviewed

Purpose To determine, by using Rasch analysis, whether the McMonnies questionnaire possesses the properties of a measure and whether screening for dry eye syndromes (DESs) can be enhanced by using different scoring approaches. Methods The questionnaire was self-administered by 43 female Sjogren syndrome patients (>45 years) recruited from a specialized rheumatology clinic and 140 age-matched control subjects. Data were scaled by using Rasch analysis and were assessed for response category behavior and ability to reliably discriminate between severity of the participant's dry eye symptoms (i.e., person separation reliability; minimum acceptable value, 0.80). Standard summary statistics of screening performance were calculated for raw and Rasch-scaled scores from receiver-operating characteristic analysis including area under the curve (AUC). Best predictors (i.e., questions) from a discriminant analysis were used to calculate a discriminant function for both Rasch-scaled and raw scores. Results Response categories were not used as intended, necessitating a collapse of categories. Person separation reliability was inadequate (0.75). A Rasch-scaled discriminant cutoff score of -2.29 logits from seven items provided an AUC of 0.99 with 95% sensitivity. However, discriminant raw score from modification in the scoring of a question (e.g., use of medications), used as one rather than multiple questions, provided an AUC (0.97) that was not significantly different (z = 1.11, P = 0.27), with 98% sensitivity, and required only two questions. Conclusions In this population, the McMonnies questionnaire does not function as a measure. However, various scoring methods can be used to efficiently screen for DES.

Purpose: The visual functioning index (VFI) was one of the first questionnaires developed using classical test theory to assess outcomes of cataract surgery. However, it was not Rasch-validated. The objective of this study was to examine the psychometric properties of the VFI using Rasch analysis in patients with cataract. Methods: The 11-item VFI was self-administered to 243 patients (mean age 73.9 years) drawn from a cataract surgery waiting list. We examined the response category thresholds, item fit statistics, differential item functioning and unidimensionality for the VFI and its three subscales. Results: Category thresholds were ordered. The person separation and reliability were low, indicating the poor discriminatory ability of the VFI. No items misfit but there was suboptimal targeting of item difficulty to patient ability. On the whole the items in the VFI were too easy for the sample. Only one item showed moderate differential item functioning. Conclusion: The VFI does not meet the stringent requirements of the Rasch model. However adding more items to suit the more able patients with cataract as well as those awaiting second-eye cataract surgery could optimize the VFI.

The Distance Vision Scale (DVS) is a self-assessment of visual acuity (VA). Like VA testing in which letter reading becomes progressively difficult through the test, DVS questions have a hierarchy of difficulty (Guttman scale). The aims were to determine whether the DVS fulfills Guttman scaling criteria and to test the relationship between DVS score and VA in a cataract population.Responses of 113 participants to the DVS were subjected to Guttman analysis. Standard criteria of scalability were evaluated that included the coefficient of reproducibility (CR), minimal marginal reproducibility (MMR), and coefficient of scalability (CS). The relationship between total item score and binocular visual acuity was determined.Five participants were excluded because of missing data. Regularity in the banding pattern of the scalogram of the 108 participants was suggestive of a deterministic Guttman scale. Analyses showed that DVS satisfies the criteria for classification as a valid unidimensional and cumulative scale, as CS (0.93), CR (0.99), and MMR (0.85) values fall within the desired range. The statistically significant correlation between the total item score and binocular VA was 0.24.The DVS fits the Guttman scale, supporting the deterministic model underlying the scale. It correlates poorly with VA, suggesting it taps aspects of visual performance and other issues beyond high-contrast VA. The DVS could be used as an outcome measure to evaluate change over time and could be used to set achievable treatment objectives because of its hierarchical properties.

To evaluate the change in visual functioning (VF) using the L. V. Prasad-Functional Vision Questionnaire II (LVP-FVQ II) following multidisciplinary low vision rehabilitation (LVR) services in children with low vision (LV).Children with LV referred for the first time to the Centre for Sight Enhancement were administered the LVP-FVQ II at baseline and at 3 to 4 months' follow-up to assess the outcomes of LVR. Participants' responses to the LVP-FVQ II at baseline and follow-up were transformed into interval-level estimates of VF using Rasch analysis. Cohen's d values (effect size) were used to estimate the magnitude of change in VF.A total of 183 participants completed the rehabilitation (mean age, 11.9 years; male, 57%). More than one-half of the participants had retinal disorders (55%) and most were moderately visually impaired (20/60-20/200, 76.5%). Using the LVP-FVQ II, significant improvement in VF after rehabilitation was recorded (P0.0001) and the increase in VF (SD) was 1.20 (1.82) logits. Using Cohen's d, the magnitude of the improvement in LVR intervention at follow-up was found to be 0.75, indicating nearly large treatment effect.Ours is the first study to provide strong evidence that LVR services result in nearly large and significant improvements in the overall VF in children with LV, regardless of the cause of LV. These results should encourage eye care professionals to refer children with LV to LVR services. Further investigation is needed to determine if the improvement in VF can be sustained over a longer duration (4 months).

Purpose To evaluate the psychometric properties of the Adult Strabismus-20 (AS-20)- a health-related quality of life (HRQoL) questionnaire in adults with strabismus, and if flawed, to revise the AS-20 and its subscales creating valid measurement scales. Methods 584 adults (meanage, 27.5 years) with strabismus were recruited from an outpatient clinic at a South Indian tertiary eye care centre and were administered the AS-20 questionnaire.The AS-20 was translated and back translated into two Indian languages. The AS-20 and its two 10-item subscales – ‘psychosocial’ and ‘function’were assessed separately for fit to the Rasch model, including an assessment of the rating scale, unidimensionality (by principal components analysis), measurement precision by person separation reliability, PSR, targeting, and differential item functioning (DIF; notable > 1.0 logits). Results Response categories were not used as intended, thereby, required re-organization and reducing their number from 5 to 3. The AS-20 had adequate measurement precision (PSR = 0.87) but lacked unidimensionality; however, deletion of the six multi-dimensionality causing items and an additional three misfitting items resulted in 11-item unidimensional questionnaire (AS-11). Two items failed to satisfy the model expectations in the ‘psychosocial’ subscale and were deleted – resulting in an 8-item unidimensional scale with adequate PSR (0.81) and targeting (0.23 logits). One item misfit in the ‘function’ subscale and was deleted—resulting in a 9 item Rasch-revised unidimensional subscale with acceptable PSR (0.80) and targeting (0.97 logits).None of the items displayed notable DIF by age, gender and level of education. Conclusions The AS-11 and its two Rasch-revised subscales – 8-item psychosocial and 9-item function subscale may be more appropriate than the original AS-20 and its two 10-item subscales for use as unidimensional measures of HRQoL in adults with strabismus in India. Further work is required to establish the validity of the revised rating scale.

Background Parents of a child with disability must cope with greater demands than those living with a healthy child. Coping refers to a person’s cognitive or behavioral efforts to manage the demands of a stressful situation. The Coping Health Inventory for Parents (CHIP) is a well-recognized measure of coping among parents of chronically ill children and assesses different coping patterns using its three subscales. The purpose of this study was to provide further insights into the psychometric properties of the CHIP subscales in a sample of parents of children with disabilities. Methods In this cross-sectional study, 220 parents (mean age, 33.4 years; 85% mothers) caring for a child with disability enrolled in special schools as well as in mainstream schools completed the 45-item CHIP. Rasch analysis was applied to the CHIP data and the psychometric performance of each of the three subscales was tested. Subscale revision was performed in the context of Rasch analysis statistics. Results Response categories were not used as intended, necessitating combining categories, thereby reducing the number from 4 to 3. The subscale – ‘maintaining social support’ satisfied all the Rasch model expectations. Four item misfit the Rasch model in the subscale –maintaining family integration’, but their deletion resulted in a 15-item scale with items that fit the Rasch model well. The remaining subscale – ‘understanding the healthcare situation’ lacked adequate measurement precision (

To determine the surgical outcome after initial surgery in children with primary developmental glaucoma (PDG).Six hundred and twenty-four eyes of 360 consecutive patients who underwent primary combined trabeculotomy-trabeculectomy (CTT) for PDG from January 1990 to June 2004 were studied. The main outcome measures were pre- and postoperative intraocular pressures (IOPs), corneal clarity, visual acuities, refractive errors, success rate, time of surgical failure, complications, and factors associated with poor outcome.IOP reduced from 28.1+/-7.5 to 14.9+/-5.9 mmHg (P0.0001). Probability of success (IOP21 mmHg) was 85.2, 80.4, 77.2, 72.6, 66.2, and 57.5% at first, second, third, fourth, fifth, and sixth years, respectively (Kaplan-Meier analysis). The mean follow-up period was 20.3+/-25.6 months (median, 6 months). Preoperatively, 243 eyes (67.5%) had significant corneal oedema. Postoperatively, normal corneal transparency was achieved in 162 eyes (46.0%). Data on Snellen visual acuity were available in 100 patients (27.8%). At the final follow-up visit, 42 patients (42.0%) had normal visual acuity (or=20/60). Myopia (mean spherical equivalent, 6.1 D) was the most common (75.0%) refractive error. In multivariate analyses, failure increased by three-fold in the presence of preoperative IOP35 mmHg (hazards ratio (HR)=3.12; 95% confidence interval (CI), 1.4-6.7) and two-fold in cases with a history of prior glaucoma surgery (HR=2.57; 95% CI, 1.1-6.0). There were no major intraoperative complications, bleb-related infection, or endophthalmitis.This series shows that prolonged IOP control can be achieved in patients with PDG and 42% of the patients gained normal visual acuity.

PURPOSE. To establish the genotype-phenotype correlations of various CYP1B1 (human cytochrome P450) mutations in patients in India with primary congenital glaucoma (PCG). METHODS. The study cohort comprised 146 patients with PCG from 138 pedigrees. Patients were analyzed for six distinct CYP1B1 mutations by sequencing and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods. A severity index for grading various PCG phenotypes was constructed based on clinical parameters. RESULTS. Six mutations were identified in 45 patients analyzed and genotype-phenotype correlations were established for 43 of them. The percentages of severe phenotypes associated with various mutations in at least one eye were: frameshift, 100%; G61E, 66.7%; P193L, 62.5%; E229K, 80%; R368H, 72%; R390C, 83.3%. The frameshift mutation resulted in blindness. Based on the severity index, the disease severity was graded from normal to severe and the prognosis from good to very poor (blind). De novo mutation was identified in one family. CONCLUSIONS. This is the first study to attempt to devise a severity index for grading various PCG phenotypes and to use genotype as an indicator to predict the prognoses of the disorder. This index may help guide therapy and counseling of the afflicted family regarding the progression of the disorder. All patients with severe phenotypes showed poor prognoses (r = 0.976; P < 0.0001). The data derived from this study could be used as an added clinical tool in disease management. Integrated management of PCG that makes use of a genetic approach could yield better results than medical, surgical, and rehabilitation interventions alone.

PURPOSE - To develop a reliable and valid questionnaire (the LV Prasad-Functional Vision Questionnaire, LVP-FVQ) to assess self-reported functional vision problems of visually impaired school children. METHODS - The LVP-FVQ consisting of 19 items was administered verbally to 78 visually impaired Indian school children aged 8 to 18 years. Responses for each item were rated on a 5-point scale. A Rasch analysis of the ordinal difficulty ratings was used to estimate interval measures of perceived visual ability for functional vision performance. RESULTS - Content validity of the LVP-FVQ was shown by the good separation index (3.75) and high reliability scores (0.93) for the item parameters. Construct validity was shown with good model fit statistics. Criterion validity of the LVP-FVQ was shown by good discrimination among subjects who answered "seeing much worse" versus "as well as"; "seeing much worse" versus "as well as/a little worse" and "seeing much worse" versus "a little worse," compared with their normal-sighted friends. The task that required the least visual ability was "walking alone in the corridor at school"; the task that required the most was "reading a textbook at arm’s length." The estimated person measures of visual ability were linear with logarithm of the minimum angle of resolution (logMAR) acuity and the binocular high contrast distance visual acuity accounted for 32.6% of the variability in the person measure. CONCLUSIONS - The LVP-FVQ is a reliable, valid, and simple questionnaire that can be used to measure functional vision in visually impaired children in developing countries such as India.

This study aimed to investigate the safety and efficacy of trabeculectomy with intraoperative mitomycin C (MMC) in the management of eyes with neovascular glaucoma (NVG).Fifteen eyes of 14 patients with NVG were included in the study. NVG was secondary to central retinal vein occlusion (3 eyes), hemiretinal vein occlusion (2 eyes), proliferative diabetic retinopathy (8 eyes), branch retinal vein occlusion (1 eye) and idiopathic (1 eye). Preoperative retinal ablation was performed in eyes with evidence of posterior segment ischaemia. Following this, all eyes underwent trabeculectomy with intraoperative MMC (0.4 mg/ml for 3 minutes). Clinical outcome assessment included visual acuity, intraocular pressure (IOP), bleb appearance, identification of complications and antiglaucoma medications required to control IOP.The mean IOP decreased from 38.6 +/- 12.9 mmHg (range, 15-64 mmHg) to 17.4 +/- 9.33 mmHg (range, 4-34 mmHg) (P = 0.001). Preoperative visual acuity ranged from light perception to 6/9 in the affected eye. Thirteen (86.6%) of 15 eyes improved vision or retained preoperative vision, one (6.7%) eye lost light perception and one (6.7%) eye developed tractional retinal detachment two years after trabeculectomy. Ten (66.7%) of 15 eyes were classified as surgical success with a mean follow-up of 28.6 +/- 26.3 months (range, 2-82 months). None of the patients developed choroidal haemorrhage, hypotony maculopathy, late onset bleb leak or endophthalmitis.Trabeculectomy with intraoperative MMC is a good treatment modality in the management of eyes with NVG.

BACKGROUND: Depression and anxiety are two common normal responses to a chronic disease such as glaucoma. This study analysed the measurement properties of the depression screening instrument - Patient Health Questionnaire-9 (PHQ-9) using Rasch analysis to determine if it can be used as a measure. METHODS: In this hospital-based cross-sectional study, the PHQ-9 was administered to primary glaucoma adults attending a glaucoma clinic of a tertiary eye care centre, South India. All patients underwent a comprehensive clinical evaluation. Patient demographics and sub-type of glaucoma were abstracted from the medical record. Rasch analysis was used to investigate the following properties of the PHQ-9: behaviour of the response categories, measurement precision (assessed using person separation reliability, PSR; minimum recommended value 0.80), unidimensionality (assessed using item fit [0.7-1.3] and principal components analysis of residuals), and targeting. RESULTS: 198 patients (mean age ± standard deviation = 59.83±12.34 years; 67% male) were included. The native PHQ-9 did not fit the Rasch model. The response categories showed disordered thresholds which became ordered after category reorganization. Measurement precision was below acceptable limits (0.62) and targeting was sub-optimal (-1.27 logits). Four items misfit that were deleted iteratively following which a set of five items fit the Rasch model. However measurement precision failed to improve and targeting worsened further (-1.62 logits). CONCLUSIONS: The PHQ-9, in its present form, provides suboptimal assessment of depression in patients with glaucoma in India. Therefore, there is a need to develop a new depression instrument for our glaucoma population. A superior strategy would be to use the item bank for depression but this will also need to be validated in glaucoma patients before deciding its utility.

Purpose We evaluated the utility values (UVs), using the time trade off (TTO) technique, associated with primary glaucoma and varying degrees of visual field (VF) loss. Methods In this cross-sectional study, 198 adults (mean age, 59.8 years) with primary glaucoma were recruited from the glaucoma clinic of a tertiary center in Hyderabad, South India. Each patient underwent comprehensive glaucoma evaluation, and completed the utility (TTO) and Glaucoma Quality of Life-15 questionnaires (Rasch version, Glaucoma Activity Limitation [GAL]-10). Better mean deviation (MD, using Humphrey Field Analyzer program 24-2) between two eyes was used to classify participants into mild, moderate, and severe VF loss groups. Utilities (range, 0.0-1.0) derived by TTO technique (lifetime traded against perfect vision) and interval level Rasch scores of GAL-10 were used for analyses. Results Mean UV was 0.81 (95% confidence interval [CI], 0.78-0.84); that is, a decrease in quality of life (QoL) of 19%. Of the subjects, 59% were willing to trade lifetime in return of perfect vision; those willing to trade were significantly younger with poorer acuity in the worse-seeing eye. In univariate and multivariate analysis, severe VF loss in the worse eye was associated with lower UV (β = -0.108; 95% CI, -0.201 to -0.014; P = 0.02). Conclusions Our results show that primary glaucoma in adults causes substantial decrease in UVs (and QoL thereof), and is highly dependent on the severity of VF loss in the worse eye.

PURPOSE A multi-attribute utility instrument (MAUI) consists of a descriptive system in which the items and responses seek information about a concept of the universe of health-related quality of life (QoL), and responses to these items then are weighted and combined to produce the index. To our knowledge, the 6-item Vision and Quality of Life Index (VisQoL) is the only available vision-related MAUI, developed and validated in Australia, specifically for visually impaired (VI) populations. To our knowledge, the psychometric properties of the VisQoL have not yet been investigated in an Indian VI sample; this was the aim of our study. METHODS The Indian VisQoL was administered to 349 VI adults face-to-face by a trained interviewer at the Vision Rehabilitation Centres of a tertiary eye care facility, South India. Rasch analysis was used to assess the psychometric properties. RESULTS Rescoring was necessary for all except one item before ordered thresholds were obtained. All items fit the Rasch model and unidimensionality was confirmed. Person separation was acceptable (2.01), indicating that the instrument can discriminate among three strata of participants" vision-related QoL (VRQoL). The VisQoL items were targeted substantially to the participants" VRQoL (-0.69 logits). One item ("ability to have friendships") demonstrated large differential item functioning by work status; working participants reported the item to be more difficult (-1.13 logits) relative to other items when compared to the nonworking participants. CONCLUSIONS The 6-item Indian VisQoL satisfies unidimensional Rasch model expectations in VI patients. Disordering of response categories was evident; replication is required before a common rescoring option should be considered.

Purpose Previous Rasch analysis of the Activities of Daily Vision Scale (ADVS) did not address psychometric properties of its subscales or provide detailed assessment of dimensionality (whether the ADVS measures one or multiple constructs). This study was designed to examine these properties. Methods Two hundred thirty-two participants (mean age, 74.2 years) awaiting cataract surgery self-administered the ADVS. Rasch analysis was used to assess the ADVS and its five subscales for unidimensionality (by principal components analysis, [PCA]), precision by person separation (discrimination between strata of participant ability), and targeting (matching of item difficulty to participant ability). Adequate person separation (minimum acceptable value, 2.0) is the fundamental requirement for measurement. Results Only the near vision subscale had adequate measurement properties (person separation, 2.30). The entire ADVS showed a misfit to the Rasch model and lacked unidimensionality. PCA confirmed the presence of two additional traits-driving and glare disability-but neither possessed adequate person separation when assessed individually. Deleting these traits restored unidimensionality, but additional items misfit, necessitating item reduction. Finally, an eight-item ADVS-Near Vision Scale showed good fit and unidimensionality. Its contents were identical with the original near vision subscale. Targeting was suboptimal (2.30 logits). Conclusions Only one subscale, near vision, met the criteria for measurement. The revised eight-item ADVS-Near Vision subscale is a unidimensional measure of visual disability in cataract patients with mild visual disability. However, it is limited by measurement of near visual ability only. For more comprehensive measurement of visual disability, other questionnaires such as Catquest-9SF are preferable for cataract surgery outcomes assessment.

AIM—To evaluate the efficacy of intravitreal dexamethasone co-administered with intravitreal antibiotics along with vitrectomy in the management of exogenous bacterial endophthalmitis. METHODS—In a prospective randomised clinical trial, 63 patients (63 eyes) with suspected bacterial endophthalmitis (postoperative and post-traumatic) were treated with vitrectomy and intravitreal antibiotics and randomised to intravitreal dexamethasone (IOAB with = 29 eyes) and no dexamethasone (IOAB without = 34 eyes). Inflammation score (IS) and visual acuity were measured by two masked observers before surgery, and at 1, 4, and 12 weeks after surgery in both the groups. RESULTS—There was significant reduction (p

PURPOSE To determine the distribution of perceived visual ability for functional vision performance among persons with low vision in the Indian state of Andhra Pradesh. METHODS As part of a population-based epidemiologic study, the Andhra Pradesh Eye Disease Study (APEDS), a 16-item visual function questionnaire was designed and applied to 7363 persons older than 15 years, to record the levels of difficulty perceived by the subjects. Of these, 123 persons were found to have low vision. Rasch analysis was used to convert the ordinal difficulty ratings of these 123 persons into interval measures of perceived visual ability for functional vision. RESULTS Content validity of the questionnaire was demonstrated by good separation indices (3.17 and 5.44) and high reliability scores (0.91 and 0.97) for person and item parameters. Construct validity was shown with model fit statistics. Criterion validity of the questionnaire was shown by good discrimination among the general vision ratings. The functional situation that required the least visual ability was "reaching an object farther or closer than you thought"; the situation requiring the most visual ability was "recognizing small objects." Bivariate regression analysis determined that for every unit of logMAR visual acuity, perceived visual ability for functional vision decreased by 2.9 logit, which could explain 32% of the variability in the person measure. CONCLUSIONS The described assessment, across a range of visual problems, is a valid way to measure perceived ability for functional vision in persons with low vision. Perceived visual ability varies with every unit of logarithm of the minimum angle of resolution (logMAR) visual acuity.

PURPOSE. To determine the impact of visual impairment on functional vision of children in a rural population of south India. METHODS. A visual function questionnaire (LVP-VFQ) was administered to 1194 children aged 7 to 15 years identified through a systematic random sampling technique from 144 hamlets of Kariapatti in rural south India as part of a larger population-based project. Visual acuity estimations and clinical examinations for morbidity were performed in these 1194 children. A Rasch analysis was performed to validate the use of the instrument in this population. Bootstrap estimates (95% confidence intervals) of the regression coefficients were used to compare visual function scores between children with normal sight and children with uncorrected monocular and binocular visual impairment. RESULTS. The mean age of children was 10.3 ± 2.1 years. The reliability estimates were 0.82 for person ability and 0.88 for item difficulty parameters, according to the Rasch analysis. A separation index of 2.15 was obtained for person measures and 2.74 for item measures, and the mean square infit and outfit statistics were 1.03 (Z STn 0.1) and 0.99 (Z STD -0.1), respectively. Children with monocular visual impairment (bootstrap estimate [95%CI] -0.05 [-0.08 to -0.01]) and binocular visual impairment (bootstrap estimate [95%CI] -0.09 [-0.11 to -0.071) were more likely to have functional visual deficits than were normally sighted peers. CONCLUSIONS. Monocular or binocular visual impairment impacts on the functional vision of children in this rural population. Further studies are needed to determine the impact of treatment of visual impairment on functional vision in children of this population.