Efficacy of Coloured Overlays and Lenses for the Treatment of Reading Difficulty: An Overview of Systematic Reviews

Background Coloured overlays or lenses are widely available for use by children and adults with difficulties or discomfort while reading. In recent years, systematic reviews have been conducted in an attempt to establish the strength of the evidence base for this intervention. The aims of this overview is to systematically review these reviews. Method The methodology was published prospectively as a protocol (Prospero CRD42017059172). Online databases Medline, Cinahl, Ovid and the Cochrane library were searched for systematic reviews on the efficacy of coloured overlays or lenses for the alleviation of reading difficulty or discomfort. Included studies were appraised using the AMSTAR 2 checklist. Characteristics of included studies including aspects of methods, results and conclusions were recorded. Both processes were conducted independently by two reviewers and any discrepancies were resolved by discussion. Results Thirty-one studies were found via databases and other sources. After excluding duplicates and those not fitting the inclusion criteria, four reviews were included in the analysis. While all reviews were systematic, their methodology, results and conclusions differed. Three of the four concluded that there is insufficient good quality evidence to support the use of coloured overlays or lenses for reading difficulty, while one concluded that, despite research limitations, the evidence does support their use. Conclusions On balance, systematic reviews to date indicate that there is not yet a reliable evidence base on which to recommend coloured overlays or lenses for the alleviation of reading difficulty or discomfort. High quality, low bias research is needed to investigate their effectiveness in different forms of reading difficulty and discomfort for adults and children

The Development of Crowding and Interocular Interactions in a Resolution Acuity Task

Purpose.: To investigate the impact of interocular similarities of a surround stimulus on foveal resolution acuity in the normally developing visual system. Methods.: Liquid crystal shutter goggles synchronized with the monitor frame rate were used to present a Landolt C and surround bars to one or both eyes, in monocular, dichoptic, half-binocular, and binocular viewing conditions. Resolution acuity was measured under each condition in 56 normally sighted children (7 to 14 years of age) and 22 adults (21 to 38 years of age). The effect of the surround bars (crowding) was tested in a subgroup of nine children, and 10 adults. Results.: Across all age groups resolution acuity was significantly better in the binocular condition than in the other three viewing conditions (binocular summation), and was significantly better in the half-binocular (with target presented to the test eye and bars presented to both eyes) than in the dichoptic condition (target presented to test eye and bars presented to the nontested eye only). In children, but not in adults, resolution acuity was significantly better without than with bars. Conclusions.: The interocular similarities may explain the better visual resolution in the half-binocular condition than in the dichoptic condition for all age groups tested. The results suggest that interocular interactions underpinning resolution acuity under these viewing conditions are developed in early childhood. The foveal crowding effect was found to be apparent at the beginning of school age, and diminished with maturation

Visual Functions and Interocular Interactions in Anisometropic Children with and without Amblyopia

Purpose.: In uncorrected anisometropia, protracted dichoptic stimulation may result in interocular inhibition, which may be a contributing factor in amblyopia development. This study investigates the relationship between interocular interactions and anisometropic amblyopia. Methods.: Three visual functions (low-contrast acuity, contrast sensitivity, and alignment sensitivity) were measured in the nondominant eye of 44 children aged 5 to 11 years: 10 with normal vision, 17 with anisometropia without amblyopia, and 17 with anisometropic amblyopia. The dominant eye was either fully or partially occluded. The difference in nondominant eye visual function between the full-and partial-occlusion conditions was termed the interaction index. The index of each visual function was compared between subject groups. A higher index indicates stronger inhibition of nondominant eye function with partial occlusion of the dominant eye. Amblyopic children had 6 months of therapy (refractive correction and occlusion), and the reduction in interocular difference in high-contrast acuity was regarded as the treatment outcome. The relationships of the interaction index with the degree of anisometropia, the severity of amblyopia, and the treatment outcomes were examined. Results.: The acuity interaction index was significantly higher in anisometropic children with amblyopia than in those without (P = 0.003). It was positively correlated with the degree of anisometropia (r s = 0.35, P = 0.042) and the amblyopic treatment outcomes (r s = 0.54, P = 0.038). No such difference or association was found between the contrast sensitivity or alignment sensitivity interaction index and anisometropic amblyopia. Conclusions.: Interocular interactions are associated with amblyopia, the degree of anisometropia, and amblyopia treatment outcomes, but these associations are visual function dependent

Enhancement of Resolution Acuity in a Half-Binocular Viewing Condition

Purpose.: To investigate the effect of interocular stimulus similarity on foveal resolution acuity. Methods.: Liquid crystal shutter goggles synchronized with the monitor refresh rate were used to present a Landolt C and surround bars to one or both eyes, in four viewing conditions (monocular, dichoptic, half-binocular, and binocular). Resolution acuity was measured in each condition in 22 normally sighted adults. Results.: Resolution acuity was significantly better in the binocular condition than in the other three viewing conditions (binocular summation) and was significantly better in the half-binocular condition (with target presented to the test eye and bars presented to both eyes) than in the dichoptic condition (target presented to the test eye and bars presented to the nontested eye only). Conclusions.: Monocular resolution acuity depends in part on interocular similarities of the stimulus surrounding the central target. This finding may have implications in the design of stimuli for vision-training therapies

Negligible impact on posture from 5-diopter vertical yoked prisms

PURPOSE: Yoked prisms are used by some optometrists to adjust posture, but evidence to support this practice is sparse and low level. The aim of this research was to investigate whether vertical yoked prisms have an impact on posture in healthy adults. METHODS: Posture was assessed objectively in 20 healthy adults, by recording a range of joint angles or body segment locations at the ankle, hip, torso, neck, and head during participant observation of a straight-ahead target, and subsequently with eyes closed. Recording occurred before, during, and after wearing goggles with control plano lenses, and 5-diopter (D) base-up and 5-D base-down yoked prisms. In each viewing condition, the goggles were worn for 30 minutes. Interaction effects of lens/prism condition by time on joint angles and body orientation were determined. RESULTS: In the eyes-open and eyes-closed conditions, no significant lens/prism × time interaction effects were found at the torso, neck, hip, or ankle (P > 0.1). However, in both eyes-open and eyes-closed conditions a significant lens/prism × time interaction was found at the head (P = 0.031 and 0.006, respectively), with head extended (tilted backward) by up to 2.5 degrees more while viewing with base-down prisms than with plano lenses. CONCLUSIONS: In healthy adults, 5-D base-down yoked prisms were not associated with a change in body posture. A small effect on head orientation and not at other locations suggests a minimal effect on posture. Research in a larger sample and in individuals with abnormal posture is needed to verify this

Development of a novel approach to the assessment of eye-hand coordination

Background Current methods to measure eye–hand coordination (EHC) have been widely applied in research and practical fields. However, some aspects of the methods, such as subjectivity, high price, portability, and high appraisal contribute to difficulties in EHC testing. New methods The test was developed on an Apple iPad® and involves tracing up to 13 shapes with a stylus pen. The time taken to complete each trace and the spatial accuracy of the tracing is automatically recorded. The difficulty level for each shape was evaluated theoretically based on the complexity and length of outline. Ten adults aged 31.5 ± 7.8 years and five children aged 9.4 ± 1.1 years with normal vision participated. Results In adults, the time taken to trace and number of errors significantly decreased from the first to the second attempt (p < 0.05) but not thereafter, suggesting a learning effect with repeatability after a practice attempt. Time taken and number of errors in children were both higher in monocular than binocular viewing conditions (p = 0.02 and p < 0.01, respectively) while adults’ performance was similar in both viewing conditions. Comparison with existing methods Existing EHC tests are subjective in clinics and require higher skills and cost in research, and measure gross EHC. This novel test has been developed to address some of the limitations. Conclusions The test is engaging for children and adults and is an objective method with potential for the assessment of fine EHC, suited to clinic-based and research use in ophthalmic or brain trauma settings, and in developmental disorders

Increase in ACC Oxidase Levels and Activities During Paradormancy Release of Leafy Spurge (Euphorbia Esula) Buds

The plant hormone ethylene is known to affect various developmental processes including dormancy and growth. Yet, little information is available about the role of ethylene during paradormancy release in underground adventitious buds of leafy spurge. In this study, we examined changes in ethylene evolution and the ethylene biosynthetic enzyme ACC oxidase following paradormancy release (growth induction). Our results did not show an obvious increase in ethylene during bud growth. However, when buds were incubated with 1 mM ACC, ethylene levels were higher in growing than non-growing buds, suggesting that the levels of ACC oxidase increased in growing buds. Real-time qPCR indicated that the transcript of a Euphorbia esula ACC oxidase (Ee-ACO) increased up to threefold following growth induction. In addition, a 2.5- to 4-fold increase in ACO activity was observed 4 days after decapitation, and the Ee-ACO accounted for 40 % of the total ACO activity. Immunoblot analyses identified a 36-kD Ee-ACO protein that increased in expression during bud growth. This protein was highly expressed in leaves, moderately expressed in crown buds, stems and meristems, and weakly expressed in roots and flowers. Immunolocalization of Ee-ACO on growing bud sections revealed strong labeling of the nucleus and cytoplasm in cells at the shoot apical meristem and leaf primordia. An exception to this pattern occurred in cells undergoing mitosis, where labeling of Ee-ACO was negligible. Taken together, our results indicated an increase in the levels of Ee-ACO during paradormancy release of leafy spurge that was not correlated with an increase in ethylene synthesis

Barriers to childhood cataract services across India. A mixed methods study using the Theoretical Domains Framework (TDF) of behaviour change

Purpose : Early identification and presentation for childhood cataract surgery remains a major challenge in developing countries. The main aim of this study was to identify potential barriers to childhood cataract services from the perspective of parents’ and carers’, as a critical step towards achieving the timely uptake of cataract services. Methods : We used a mixed methods explanatory sequential study and interviewed 572 parents/carers attending tertiary hospitals in 8 states across India for their child's cataract surgery. We collected information on barriers to accessing services using a 12-item questionnaire and for each reported barrier, responses recorded on a 5 point scale ranging from “low to high importance”. Based on the quantitative data, in-depth interview questions were prepared and 35 interviews were conducted with randomly selected parents/ carers. Majority of these interviews were conducted at the hospital and /at home for those who did not undergo the surgery. Quantitative questionnaires were completed by the trained interviewer and responses were recorded in a pre-designed format. In-depth interviews were audio taped and transcribed for analysis. Quantitative data were analysed using SPSS 22 while qualitative data were organised with NVivo 11 and a thematic analysis was conducted utilising TDF, an integrative framework of theories. Results : From the 831 responses the 5 most important barriers were: economic (40%; n=222); child too young for surgery (17%; n=97); the problem was not felt as severe (16%; n=90); distance (14.5%; n=83) and no one to accompany to the hospital (9.5%; n=54). In addition, being advised by a local ophthalmologist to delay the surgery was also reported (n=16). Domains identified by the TDF included “Knowledge”, “Beliefs about consequences”, “Intentions”, “Goals”, “Decision processes”, “Environmental context and resources”, “Social influences and emotion”. This comprehensive TDF approach enabled us to understand the parents perceived barriers to access services for the children. Conclusions : Barriers to accessing childhood cataract services include both practical concerns relating to the family’s socio economic status as well as obstacles from the providers. Mapping out the barriers is necessary to design appropriate intervention for achieving positive behaviour change that can have potential social and economic impact