Visual and binocular status in elementary school children with a reading problem / Estado visual y binocular en niños de primaria con dificultades lectoras

Purpose: This descriptive study provides a summary of the binocular anomalies seen in elementary school children identified with reading problems. Methods: A retrospective chart review of all children identified with reading problems and seen by the University of Waterloo, Optometry Clinic, from September 2012 to June 2013. Results: Files of 121 children (mean age 8.6 years, range 6-14 years) were reviewed. No significant refractive error was found in 81% of children. Five and 8 children were identified as strabismic at distance and near respectively. Phoria test revealed 90% and 65% of patients had normal distance and near phoria. Near point of convergencia (NPC) was < 5cm in 68% of children, and 77% had stereoacuity of ≤40seconds of arc. More than 50% of the children had normal fusional vergence ranges except for near positive fusional vergencce (base out) break (46%). Tests for accommodation showed 91% of children were normal for binocular facility, and approximately 70% of children had an expected accuracy of accommodation. Conclusion: Findings indicate that some children with an identified reading problem also present with abnormal binocular test results compared to published normal values. Further investigation should be performed to investigate the relationship between binocular vision function and reading performance

Objetivo: Este estudio descriptivo aporta un resumen de las anomalías binoculares observadas en niños de primaria en los que se identificaron problemas de lectura. Métodos: Revisión retrospectiva de las historias clínicas de todos los niños en los que se identificaron problemas de lectura, examinados en la Universidad de Waterloo, Clínica de Optometría, desde Septiembre de 2012 a Junio de 2013. Resultados: Se revisaron las historias de 121 niños (edad media 8,6 años, rango 6-14 años). No se encontró ningún error refractivo significativo en el 81% de los niños. Se identificaron cinco y ocho niños con estrabismo de visión lejana y cercana, respectivamente. La prueba de foria reveló que el 90% y 65% de los pacientes padecían foria en rango de normalidad para lejos y cerca. El punto próximo de convergencia (PPC) fue < 5cm en el 68% de los niños, y el 77% reflejó estereoagudeza ≤ 40 segundos de arco. Más del 50% de los niños tenía rangos de vergencia fusional normal, excepto para el punto de rotura de vergencia fusional positiva de cerca (46%). Las pruebas de acomodación reflejaron que el 91% de los niños tenía una flexibilidad binocular normal, y aproximadamente el 70% de los niños tenía una precisión de acomodación con arreglo a lo previsto. Conclusión: Los hallazgos indican que algunos niños con dificultades lectoras identificadas presentan también alteraciones en los resultados de las pruebas binoculares, en comparación a los valores normales publicados. Deberá investigarse más con respecto a la relación entre la función de la visión binocular y el rendimiento lector

Development and validation of Visual Impairment as a Risk for Falls Questionnaire.

Purpose: visual impairment is associated with an increased risk of falls, yet eye care professionals are infrequently members of falls prevention clinics. The aim of this preliminary study was to validate a newly created Visual Impairment as a Risk for Falls Questionnaire intended to be used by those professionals not involved in eye care. Methods: about 53 participants with various visual impairments known to be associated with falls and 33 participants with normal sight were contacted within 4 months of a full oculo-visual assessment and were asked the questions from the current questionnaire pertaining to their visual function. A retrospective file review was undertaken and the sensitivity and specificity of participants' responses were calculated compared to the actual vision impairment based on the findings from their visual assessment. Results: the question regarding ability to read was included to identify people with central vision loss, a risk factor for falling. It was found to have sensitivity of 74% and specificity of 87%. Both sensitivity and specificity improved when participants with cognitive impairment were excluded. The question on recognising facial features gave sensitivity of 73% and specificity of 97% for this subgroup. However, questions related to impairments in stereopsis and peripheral fields were not useful. Conclusion: the study demonstrates that several questions of the new questionnaire are useful; however, further testing with a larger population is needed to fully validate the questionnaire for use by health care professionals.

Visual and binocular status in elementary school children with a reading problem.

PURPOSE: This descriptive study provides a summary of the binocular anomalies seen in elementary school children identified with reading problems. METHODS: A retrospective chart review of all children identified with reading problems and seen by the University of Waterloo, Optometry Clinic, from September 2012 to June 2013. RESULTS: Files of 121 children (mean age 8.6 years, range 6-14 years) were reviewed. No significant refractive error was found in 81% of children. Five and 8 children were identified as strabismic at distance and near respectively. Phoria test revealed 90% and 65% of patients had normal distance and near phoria. Near point of convergencia (NPC) was <5cm in 68% of children, and 77% had stereoacuity of ≤40seconds of arc. More than 50% of the children had normal fusional vergence ranges except for near positive fusional vergencce (base out) break (46%). Tests for accommodation showed 91% of children were normal for binocular facility, and approximately 70% of children had an expected accuracy of accommodation. CONCLUSION: Findings indicate that some children with an identified reading problem also present with abnormal binocular test results compared to published normal values. Further investigation should be performed to investigate the relationship between binocular vision function and reading performance.

Contact lens fitting and training in a child and youth population.

PURPOSE: To determine the ease with which children and youths without previous soft contact lens (SCL) experience were able to handle, care for, adapt and be fitted with SCLs. METHODS: 179 children aged 8-16 were recruited. Study visits included: screening and training visits, 1-week and 3-month follow-ups. During the training visit, the time taken to demonstrate proficiency in lens insertion and removal and care was recorded. A second training visit was scheduled if necessary. RESULTS: Nine children did not complete the screening visit and eight discontinued during the study. Of those eight, seven discontinued during the first week and one before the 3-month visit. Of those recruited, 90.5% (162/179) were successfully fitted and completed the study. A majority of children were dispensed with lenses at the first training visit (94.6%, 162/171). The mean training time for all children was 30 min. There were no statistically significant differences in the number of lenses required to fit or instruction time by age group (p > 0.05) or gender (p > 0.05). Nine participants (5.3%, 9/171) required a second training visit with four still unable to handle lenses (2.3%, 4/171). By the 1-week visit 13.2% (22/167) of participants either lost or tore lenses, no subsequent lost or torn lenses occurred. No serious adverse events occurred during the study. CONCLUSION: Children and youths with no previous contact lens experience were easily fitted, able to successfully wear and care for lenses. The results of this study should encourage practitioners to recommend SCLs as a vision correction option.

Measuring Infant Visual Acuity with Gaze Tracker Monitored Visual Fixation.

PURPOSE: To validate a method of measuring grating acuity with remote gaze tracking (GT) against a current clinical test of visual acuity (VA), the Teller Acuity Cards (TACs), as part of the development of an automated VA test for infants. METHODS: Visual acuity for computer-generated horizontal square-wave gratings was determined from relative fixation time on a grating area compared with the background. In experiment 1, binocular VA was based on eye movements with a GT in 15 uncorrected myopic adults and compared with VA measured with subjective responses with the same stimuli and with the TACs. In experiment 2, binocular VA was determined in 19 typically developing infants aged 3 to 11 months on two visits with both the GT and TACs. RESULTS: In adults, the mean difference between VA measured by the GT and TACs was 0.01 log cycles per degree (cpd) and the 95% limits of agreement were 0.11. One hundred percent of GT VA results were within 0.5 octave of the TACs' VAs. The mean difference between the GT and TACs for infants was 0.17 log cpd on both the first and second visit (95% limits of agreement, 0.42 and 0.47, respectively). The mean difference between test and retest for infant GT VA was 0.06 log cpd, and limits of agreement for repeatability were 0.48 log cpd. In infants, both the TACs and the GT had a reliability of 89% within less than or equal to 1 octave between visits. Gaze tracking VA improved with age and is in agreement with published norms. CONCLUSIONS: The agreement between the TACs and GT in adults and infants validates the method of measuring grating acuity with the remote GT. These results demonstrate its potential for an automated test of infant VA.

Bifocals in Down syndrome study (BiDS): analysis of video recorded sessions of literacy and visual perceptual skills.

PURPOSE: In this longitudinal study, a group of school children with Down syndrome (DS) and reduced accommodation were prescribed bifocals and followed to investigate the impact of bifocal spectacles on early literacy and visual perceptual skills. The natural progression of early literacy skills in this population along with the changes with bifocals, described by monthly subtest scores and the time taken to complete literacy and visual perceptual tasks, are reported. METHODS: Fourteen children with DS, aged eight to 18 years, were followed for five months with single vision lenses; 11 were prescribed bifocals based on their accommodative ability and followed for another five months. A battery of reading and visual perceptual tests was administered before and after prescription of bifocals. Monthly subtests of similar tasks were administered to measure progress. All the visits were videotaped to determine the time taken for the child to complete each task. RESULTS: There was no significant measurable natural progression of early literacy skills in this group of participants on the Word Identification (WI) subtest (Repeated Measures ANOVA, F [4, 24]=1.377, p = 0.271) and Dolch sight words (RMANOVA F [4, 24]= 0.344, p = 0.846). In contrast, once bifocals were prescribed there was significant improvement in the scores of the monthly subtests (p = 0.050, 0.025 and 0.023 for WI, Dolch sight words and numbers, respectively) and the rate of progress in monthly scores improved for WI (p = 0.008). Repeated measures Analysis of Variance showed a significant decrease in the completion times with bifocals for the WI test in the full battery of tests (p = 0.0015). There was significant correlation between the improvement in focus with bifocals and the decrease in completion time for the WI task (p = 0.004). CONCLUSIONS: This study demonstrates no significant natural progression over a five-month period in the group of participants with Down syndrome; however, with bifocals, faster and improved performance on some literacy skills was observed. We recommend that bifocals be considered in children with Down syndrome presenting with inadequate accommodation to optimise their educational potential.

Bifocals in children with Down syndrome (BiDS) - visual acuity, accommodation and early literacy skills.

PURPOSE: Reduced accommodation is seen in children and young adults with Down syndrome (DS), yet providing bifocals has not become a routine clinical management. This study investigates the impact of bifocals on visual function, visual perceptual and early literacy skills in a group of school children with DS. METHODS: In this longitudinal study, each child was followed for 5months with single-vision (SV) lenses after which bifocals were prescribed if required, based on their accommodative response. Visual acuity (VA), accommodation, perceptual and literacy skills were measured after adaptation to bifocals and 5months later. Educational progress and compliance with spectacle wear were assessed through school and parental reports. RESULTS: Fourteen children and young adults with DS participated in the study. Eighty-five percent required bifocals with additions ranging from +1.00D to +3.50D. The mean near logMAR VA improved with bifocals (p=0.007) compared to SV lenses. Repeated measures anova showed that there was more accurate focus (less accommodative lag) through the bifocals (p=0.002), but no change in the accommodation exerted through the distance portion compared to SV lenses (p=0.423). There was a main effect of time on sight words (p=0.013), Word Identification (p=0.047), Visual Closure (p=0.006) and Visual Form Constancy (p=0.001). CONCLUSION: Bifocals provide clearer near vision in DS children with reduced accommodation. This is shown by improved VA and decreased lag of accommodation. The results indicate that the improvement in VA results in improved scores in early literacy skills. Better compliance with bifocals over SV lenses was seen.

Bifocals in Down Syndrome Study (BiDS): design and baseline visual function.

PURPOSE: Among children and young people with Down syndrome (DS) there is a high prevalence of reduced accommodation. Prescribing bifocals for these patients has not become fully clinically accepted, although it would be anticipated to improve visual acuity (VA). The aim of this study is to investigate the impact of bifocal correction on VA, visual perceptual skills and early literacy development in children with DS who have reduced accommodation and who are provided with a bifocal correction. This paper describes the study design and the baseline optometric findings. METHODS: We have chosen a longitudinal design with frequent measures of subtests of performance to control for progression with time. The main outcome measures are early literacy and visual perception skills. Secondary outcomes are VA and accommodative function. These are measured at baseline, the participant followed for 6 months when bifocals are prescribed if necessary, and the participants were followed for another 6 months with bifocals. RESULTS: Fourteen participants with DS aged 8 to 19 years were enrolled. At baseline 79% required a change in their distance spectacle prescription. One hundred percent had reduced accommodation both before and after new single vision glasses were prescribed. None had an adverse reaction to 0.5 or 1% Cyclopentolate. All the subjects were able to perform either a distance or near crowded Patti-pics symbols test and 93% were able to perform both. There was a significant improvement of near VA with the new single vision spectacles (p = 0.015). The mean binocular distance VA was 0.362 +/- 0.17 logMAR whereas binocular near VA was 0.489 +/- 0.235. CONCLUSION: This study confirms previous findings of a high prevalence of reduced accommodation and shows that near VA is reduced compared to distance VA. The present results indicate that all subjects might benefit from bifocals.

Dyslexia: a review of two theories.

Optometrists will frequently see patients, who may have a diagnosis or a suspected diagnosis of dyslexia (specific reading disorder) and will need to manage and counsel such patients. There are many propounded theories on the cause(s) of dyslexia. Although most professionals in this area consider that dyslexia is chiefly a linguistic disorder, the possibility of a visual component is contentious. This article is a selective review of two commonly discussed theories that suggest a visual component in dyslexia; the magnocellular deficit theory and Meares-Irlen syndrome.

Brugia malayi: comparison of protective immune responses induced by Bm-alt-2 DNA, recombinant Bm-ALT-2 protein and prime-boost vaccine regimens in a jird model.

Immunization of jirds with Bm-alt-2 elicited partial protection against challenge infection with the filarial parasite Brugia malayi. In this study, we initially compared the protective immune responses elicited following immunization with recombinant Bm-ALT-2 protein regimen and Bm-alt-2 DNA regimen. These studies showed that protein vaccination conferred approximately 75% protection compared to DNA vaccination that conferred only 57% protection. Analysis of the protective immune responses showed that the protein immunization promoted a Th2-biased response with an increase in IL-4, IL-5 and IgG1 responses, whereas, the DNA vaccine promoted a Th1-biased response with profound IFN-gamma and IgG2a responses. Since protein vaccination gave better results than DNA vaccination, we then wanted to evaluate whether a prime-boost vaccination that combined DNA prime and protein boost will significantly increase the protective responses induced by the protein vaccine. Our results suggest that prime-boost vaccination had no added advantage and was comparatively less effective (64% protection) than the Bm-ALT-2 protein alone vaccination. Prime boost vaccination generated mixed Th1/Th2 responses with a slightly diminished Th2 responses compared to protein vaccination. Thus, our results suggest that Bm-ALT-2 protein vaccination regimen may be slightly better than prime-boost vaccine regimen and the mechanism of protection appears to be largely mediated by a Th2-biased response.