Visual demands in modern Australian primary school classrooms

BACKGROUND: The visual demands of modern classrooms are poorly understood yet are relevant in determining the levels of visual function required to perform optimally within this environment. METHODS: Thirty-three Year 5 and 6 classrooms from eight south-east Queensland schools were included. Classroom activities undertaken during a full school day (9 am to 3 pm) were observed and a range of measurements recorded, including classroom environment (physical dimensions, illumination levels), text size and contrast of learning materials, habitual working distances (distance and estimated for near) and time spent performing various classroom tasks. These measures were used to calculate demand-related minimum criteria for distance and near visual acuity, contrast and sustained use of accommodation and vergence. RESULTS: The visual acuity demands for distance and near were 0.33 ± 0.13 and 0.72 ± 0.09 logMAR, respectively (using habitual viewing distances and smallest target sizes) or 0.33 ± 0.09 logMAR assuming a 2.5 times acuity reserve for sustained near tasks. The mean contrast levels of learning materials at distance and near were greater than 70 per cent. Near tasks (47 per cent) dominated the academic tasks performed in the classroom followed by distance (29 per cent), distance to near (15 per cent) and computer-based (nine per cent). On average, children engaged in continuous near fixation for 23 ± 5 minutes at a time and during distance-near tasks performed fixation changes 10 ± 1 times per minute. The mean estimated habitual near working distance was 23 ± 1 cm (4.38 ± 0.24 D accommodative demand) and the vergence demand was 0.86 ± 0.07(Δ) at distance and 21.94 ± 1.09(Δ) at near assuming an average pupillary distance of 56 mm. CONCLUSIONS: Relatively high levels of visual acuity, contrast demand and sustained accommodative-convergence responses are required to meet the requirements of modern classroom environments. These findings provide an evidence base to inform prescribing guidelines and develop paediatric vision screening protocols and referral criteria.

Retinal tissue thickness in type 1 and type 2 diabetes

BACKGROUND: The objective was to investigate full retinal and inner retinal thickness in individuals with type 1 and type 2 diabetes. METHODS: Eighty-four individuals with type 1 diabetes (T1DM), 67 individuals with type 2 diabetes (T2DM) and 42 non-diabetic individuals (control group) were enrolled. Participants underwent full retinal thickness evaluation in the central retinal, parafoveal and perifoveal zones and in the retinal nerve fibre layer (RNFL) and ganglion cell complex (GCC), using spectral domain optical coherence tomography. As a preliminary step, the key variables of interest - age, sex, diabetic retinopathy (DR), duration of diabetes and HbA1c levels - were analysed and compared between the three groups. Full retinal thickness, RNFL and GCC thicknesses were also compared between the groups. The relationship between the type of diabetes and retinal tissue thickness was explored, adjusting for the five potential confounders. RESULTS: Compared to individuals with T1DM, individuals with T2DM had significantly reduced full retinal thickness in the parafovea and perifovea and reduced RNFL and GCC thickness. The mean differences were six (p = 0.020), seven (p = 0.008), six (p = 0.021) and four micrometres (p = 0.013) for the parafovea, perifovea, RNFL and GCC thicknesses, respectively. Thicknesses within the central zone (p = 0.018) and at the parafovea (p = 0.007) were significantly reduced in T2DM when compared to the control group. After adjusting for age, sex, diabetic retinopathy, duration of diabetes and HbA1c levels, the relationship between type of diabetes and retinal tissue thickness was not statistically significant (p > 0.056). CONCLUSION: Retinal tissue thickness is not significantly different between type 1 and type 2 diabetes, when adjusted for age, sex, diabetic retinopathy, duration of diabetes and HbA1c levels.

A visual profile of Queensland Indigenous children

PURPOSE: Little is known about the prevalence of refractive error, binocular vision, and other visual conditions in Australian Indigenous children. This is important given the association of these visual conditions with reduced reading performance in the wider population, which may also contribute to the suboptimal reading performance reported in this population. The aim of this study was to develop a visual profile of Queensland Indigenous children. METHODS: Vision testing was performed on 595 primary schoolchildren in Queensland, Australia. Vision parameters measured included visual acuity, refractive error, color vision, nearpoint of convergence, horizontal heterophoria, fusional vergence range, accommodative facility, AC/A ratio, visual motor integration, and rapid automatized naming. Near heterophoria, nearpoint of convergence, and near fusional vergence range were used to classify convergence insufficiency (CI). RESULTS: Although refractive error (Indigenous, 10%; non-Indigenous, 16%; p = 0.04) and strabismus (Indigenous, 0%; non-Indigenous, 3%; p = 0.03) were significantly less common in Indigenous children, CI was twice as prevalent (Indigenous, 10%; non-Indigenous, 5%; p = 0.04). Reduced visual information processing skills were more common in Indigenous children (reduced visual motor integration [Indigenous, 28%; non-Indigenous, 16%; p < 0.01] and slower rapid automatized naming [Indigenous, 67%; non-Indigenous, 59%; p = 0.04]). The prevalence of visual impairment (reduced visual acuity) and color vision deficiency was similar between groups. CONCLUSIONS: Indigenous children have less refractive error and strabismus than their non-Indigenous peers. However, CI and reduced visual information processing skills were more common in this group. Given that vision screenings primarily target visual acuity assessment and strabismus detection, this is an important finding as many Indigenous children with CI and reduced visual information processing may be missed. Emphasis should be placed on identifying children with CI and reduced visual information processing given the potential effect of these conditions on school performance.

Contact lens prescribing trends 2015 : The Efron, Morgan and Woods 16th annual survey of Australian contact lens prescribing habits

The 16th annual survey ofAustralian contact lens prescribingwas conducted from January toApril 2015. The same format as inprevious years was employed. Ane-mail was sent to all members ofOptometry Australia with a link to adownloadable questionnaire, and arequest that this be accessed, printedand completed to provide detailsof the first 10 patients fitted withcontact lenses after receipt of thequestionnaire.The survey was specifically designedto be straightforward to completewhile capturing key informationabout their patients. Practitionerswere asked general questions aboutthemselves. For each contact lensfitting, they were requested tocomplete the following details: dateof fitting, new fitting or refitting, ageand sex of patient, lens material, lensdesign, frequency of replacement,times per week of wear, modality(daily or extended wear) and caresystem. Practitioners were asked toreturn the questionnaire by fax, postor e-mail.Completed questionnaires relatingto 353 contact lens fittings werereturned, which provides a soundbasis for a meaningful analysis. Eachfitting was given a weighting based onthe number of lenses fitted per yearby the practitioner, based on the dateinformation on the form. This meansthat data generated by practitionerswho have a higher frequency of fittingcontact lenses were afforded a higherweighting than those taking longer tofit the 10 patients with lenses.This discussion concentratesprimarily on data relating to newlens fittings as opposed to refittings.We believe that new fittings are amore sensitive barometer of currentpatterns and future trends, whereasrefittings are more indicative ofprevious fitting behaviours.In keeping with other markets aroundthe world,1 the majority of lenses (62per cent) were fitted to females. Theaverage age of contact lens wearersat the time of fitting was 32.2 ± 16.5years. The age at fitting ranged fromeight to 75 years.