Do reduced visual acuity and refractive error affect classroom performance?

The role of visual acuity and refractive errors in the academic performance of children is controversial due to the variable quality of the research in this area and the mixed findings reported. This review aims to provide clarity by reviewing and critiquing relevant peer-reviewed publications and also summarises what is known regarding the visual demands of modern classroom environments. The outcomes of this review suggest that while a number of studies have investigated the role of vision in relation to children's academic performances, the veracity of the evidence obtained from the majority of these studies is undermined by methodological limitations. Comparisons between studies are constrained by differences in experimental designs, instrumentation and sample characteristics. Despite these limitations, the weight of evidence suggests there is an association between academic performance and both visual acuity and refractive error in children. However, well-designed experimental studies are necessary to further understand the relationship between these parameters.

Diagnostic capability of retinal thickness measures in diabetic peripheral neuropathy / Capacidad diagnóstica de las mediciones del grosor de la retina en la neuropatía periférica diabética

Purpose: To examine the diagnostic capability of the full retinal and inner retinal thickness measures in differentiating individuals with diabetic peripheral neuropathy (DPN) from those without neuropathy and non-diabetic controls. Methods: Individuals with (n=44) and without (n=107) diabetic neuropathy and non-diabetic control (n=42) participants underwent spectral domain optical coherence tomography (SDOCT). Retinal thickness in the central 1mm zone (including the fovea), parafovea and perifovea was assessed in addition to ganglion cell complex (GCC) global loss volume (GCC GLV) and focal loss volume (GCC FLV), and retinal nerve fiber layer (RNFL) thickness. Diabetic neuropathy was defined using a modified neuropathy disability score (NDS) recorded on a 0-10 scale, wherein, NDS ≥3 indicated neuropathy and NDS indicated <3 no neuropathy. Diagnostic performance was assessed by areas under the receiver operating characteristic curves (AUCs), 95 per cent confidence intervals (CI), sensitivities at fixed specificities, positive likelihood ratio (+LR), negative likelihood ratio (-LR) and the cut-off points for the best AUCs obtained. Results: The AUC for GCC FLV was 0.732 (95% CI: 0.624-0.840, p<0.001) with a sensitivity of 53% and specificity of 80% for differentiating DPN from controls. Evaluation of the LRs showed that GCC FLV was associated with only small effects on the post-test probability of the disease. The cut-off point calculated using the Youden index was 0.48% (67% sensitivity and 73% specificity) for GCC FLV. For distinguishing those with neuropathy from those without neuropathy, the AUCs of retinal parameters ranged from 0.508 for the central zone to 0.690 for the inferior RNFL thickness. For distinguishing those with moderate or advanced neuropathy from those with mild or no neuropathy, the inferior RNFL thickness demonstrated the highest AUC of 0.820, (95% CI: 0.731-0.909, p<0.001) with a sensitivity of 69% and 80% specificity. The cut-off-point for the inferior RNFL thickness was 97μm, with 81% sensitivity and 72% specificity. Conclusions: The GCC FLV can differentiate individuals with diabetic neuropathy from healthy controls, while the inferior RNFL thickness is able to differentiate those with greater degrees of neuropathy from those with mild or no neuropathy, both with an acceptable level of accuracy. Optical coherence tomography represents a non-invasive technology that aids in detection of retinal structural changes in patients with established diabetic neuropathy. Further refinement of the technique and the analytical approaches may be required to identify patients with minimal neuropathy (AU)

Objetivo: Examinar la capacidad diagnóstica de las mediciones del grosor total e interno de la retina, con diferenciación entre individuos con neuropatía periférica diabética (DPN), aquellos que no la padecen, y controles no diabéticos. Métodos: Cuarenta y cuatro individuos con (n=44) y sin (n=107) neuropatía diabética y participantes de control no diabéticos (n=42) fueron sometidos a una tomografía de coherencia óptica de dominio espectral (SDOCT). Se evaluó el grosor de la retina en la zona central de 1mm (incluyendo la fóvea), parafóvea y perifóvea, además del complejo de células ganglionares (GCC), el volumen de pérdida global (GCC GLV) y el volumen de pérdida focal (GCC FLV), y el espesor de la capa de fibras nerviosas de la retina (RNFL). Se definió la neuropatía diabética utilizando la versión modificada del «Neuropathy Disability Score (NDS)», sobre una escala de 0 a 10, donde el valor de NDS ≥3 indicaba neuropatía y NDS <3 ausencia de la misma. El desempeño diagnóstico se evaluó mediante las áreas bajo las curvas características operativas del receptor (AUC), intervalos de confianza del 95% (IC), sensibilidades a especificidades fijas, cociente de probabilidad positiva (CP+), y cociente de probabilidad negativa (CP-) y los puntos de corte para los mejores AUC obtenidos. Resultados: El AUC para GCC FLV fue de 0,732, 95% IC: 0,624-0,840, p<0,001 con una sensibilidad del 53% y una especificidad del 80% para la diferenciación entre DPN y los controles. La evaluación de los CP reflejó que el GCC FLV se asociaba únicamente a unos pequeños efectos en la prueba posterior de probabilidad de la enfermedad. El punto de corte calculado utilizando el índice de Youden fue del 0,48% (67% de sensibilidad y 73% de especificidad) para GCC FLV. Para distinguir a aquellos individuos con neuropatía de los que no la padecían, las AUC de los parámetros retinianos oscilaron entre 0,508 para el grosor RNFL de la zona central y 0,690 para el de la zona inferior. Para distinguir a aquellas personas con neuropatía moderada o avanzada, de aquellas con neuropatía leve, o ausencia de ella, el grosor RNFL de la zona inferior reflejó una AUC superior de 0,820, 95% IC: 0,731-0,909, p<0,001, con una sensibilidad del 69% y una especificidad del 80%. El punto de corte para el grosor RNFL inferior fue de 97μm, con un 81% de sensibilidad y un 72% de especificidad. Conclusiones: El GCC FLV puede diferenciar entre aquellos individuos con neuropatía diabética y los controles sanos, mientras que el grosor RNFL de la zona inferior es capaz de diferenciar entre aquellas personas con grados superiores de neuropatía y aquellas con neuropatía leve o ausencia de neuropatía, en ambos casos con un nivel aceptable de precisión. La tomografía de coherencia óptica supone una tecnología no invasiva que ayuda a la detección de los cambios estructurales retinianos en pacientes con neuropatía diabética establecida. Se precisa un mayor refinamiento de esta técnica, así como enfoques analíticos, para identificar a aquellos pacientes con una neuropatía mínima (AU)

Vision Problems and Reduced Reading Outcomes in Queensland Schoolchildren.

PURPOSE: To assess the relationship between vision and reading outcomes in Indigenous and non-Indigenous schoolchildren to determine whether vision problems are associated with lower reading outcomes in these populations. METHODS: Vision testing and reading assessments were performed on 508 Indigenous and non-Indigenous schoolchildren in Queensland, Australia divided into two age groups: Grades 1 and 2 (6-7 years of age) and Grades 6 and 7 (12-13 years of age). Vision parameters measured included cycloplegic refraction, near point of convergence, heterophoria, fusional vergence range, rapid automatized naming, and visual motor integration. The following vision conditions were then classified based on the vision findings: uncorrected hyperopia, convergence insufficiency, reduced rapid automatized naming, and delayed visual motor integration. Reading accuracy and reading comprehension were measured with the Neale reading test. The effect of uncorrected hyperopia, convergence insufficiency, reduced rapid automatized naming, and delayed visual motor integration on reading accuracy and reading comprehension were investigated with ANCOVAs. RESULTS: The ANCOVAs explained a significant proportion of variance in both reading accuracy and reading comprehension scores in both age groups, with 40% of the variation in reading accuracy and 33% of the variation in reading comprehension explained in the younger age group, and 27% and 10% of the variation in reading accuracy and reading comprehension, respectively, in the older age group. The vision parameters of visual motor integration and rapid automatized naming were significant predictors in all ANCOVAs (P < .01). The direction of the relationship was such that reduced reading results were explained by reduced visual motor integration and rapid automatized naming results. CONCLUSIONS: Both reduced rapid automatized naming and visual motor integration were associated with poorer reading outcomes in Indigenous and non-Indigenous children. This is an important finding given the recent emphasis placed on Indigenous children's reading skills and the fact that reduced rapid automatized naming and visual motor integration skills are more common in this group.

Diagnostic capability of retinal thickness measures in diabetic peripheral neuropathy.

PURPOSE: To examine the diagnostic capability of the full retinal and inner retinal thickness measures in differentiating individuals with diabetic peripheral neuropathy (DPN) from those without neuropathy and non-diabetic controls. METHODS: Individuals with (n=44) and without (n=107) diabetic neuropathy and non-diabetic control (n=42) participants underwent spectral domain optical coherence tomography (SDOCT). Retinal thickness in the central 1mm zone (including the fovea), parafovea and perifovea was assessed in addition to ganglion cell complex (GCC) global loss volume (GCC GLV) and focal loss volume (GCC FLV), and retinal nerve fiber layer (RNFL) thickness. Diabetic neuropathy was defined using a modified neuropathy disability score (NDS) recorded on a 0-10 scale, wherein, NDS ≥3 indicated neuropathy and NDS indicated <3 no neuropathy. Diagnostic performance was assessed by areas under the receiver operating characteristic curves (AUCs), 95 per cent confidence intervals (CI), sensitivities at fixed specificities, positive likelihood ratio (+LR), negative likelihood ratio (-LR) and the cut-off points for the best AUCs obtained. RESULTS: The AUC for GCC FLV was 0.732 (95% CI: 0.624-0.840, p<0.001) with a sensitivity of 53% and specificity of 80% for differentiating DPN from controls. Evaluation of the LRs showed that GCC FLV was associated with only small effects on the post-test probability of the disease. The cut-off point calculated using the Youden index was 0.48% (67% sensitivity and 73% specificity) for GCC FLV. For distinguishing those with neuropathy from those without neuropathy, the AUCs of retinal parameters ranged from 0.508 for the central zone to 0.690 for the inferior RNFL thickness. For distinguishing those with moderate or advanced neuropathy from those with mild or no neuropathy, the inferior RNFL thickness demonstrated the highest AUC of 0.820, (95% CI: 0.731-0.909, p<0.001) with a sensitivity of 69% and 80% specificity. The cut-off-point for the inferior RNFL thickness was 97µm, with 81% sensitivity and 72% specificity. CONCLUSIONS: The GCC FLV can differentiate individuals with diabetic neuropathy from healthy controls, while the inferior RNFL thickness is able to differentiate those with greater degrees of neuropathy from those with mild or no neuropathy, both with an acceptable level of accuracy. Optical coherence tomography represents a non-invasive technology that aids in detection of retinal structural changes in patients with established diabetic neuropathy. Further refinement of the technique and the analytical approaches may be required to identify patients with minimal neuropathy.

Retinal Tissue Thickness is Reduced in Diabetic Peripheral Neuropathy.

AIM: To investigate the relationship between diabetic peripheral neuropathy (DPN) and retinal tissue thickness. METHODS: Full retinal thickness in the central retinal, parafoveal, and perifoveal zones and thickness of the ganglion cell complex and retinal nerve fiber layer (RNFL) were assessed in 193 individuals (84 with type 1 diabetes, 67 with type 2 diabetes, and 42 healthy controls) using spectral domain optical coherence tomography. Among those with diabetes, 44 had neuropathy defined using a modified neuropathy disability score recorded on a 0-10 scale. Multiple regression analysis was performed to investigate the relationship between diabetic neuropathy and retinal tissue thickness, adjusted for the presence of diabetic retinopathy (DR), age, sex, duration of diabetes, and HbA1c levels. RESULTS: In individuals with diabetes, perifoveal thickness was inversely related to the severity of neuropathy (p < 0.05), when adjusted for age, sex, duration of diabetes, and HbA1c levels. DR was associated with reduced thickness in parafovea (p < 0.01). The RNFL was thinner in individuals with greater degrees of neuropathy (p < 0.04). CONCLUSIONS: DPN is associated with structural compromise involving several retinal layers. This compromise may represent a threat to visual integrity and therefore warrants examination of functional correlates.

Focal loss volume of ganglion cell complex in diabetic neuropathy.

BACKGROUND: The aim was to investigate the relationship between diabetic peripheral neuropathy (DPN) and abnormalities in ganglion cell complex (GCC); specifically, focal loss volume (FLV) and global loss volume (GLV). METHODS: The ganglion cell complex was evaluated using optical coherence tomography on 193 individuals (84 with type 1 diabetes, 67 with type 2 diabetes and 42 without diabetes). In those with diabetes, 88 had diabetes but no diabetic retinopathy (no DR group) and 63 had diabetes with diabetic retinopathy (DR group). Seventeen individuals in the no DR group and 27 in the DR group had diabetic peripheral neuropathy according to the neuropathy disability score (NDS). The probability of FLV and GLV being abnormal was determined. Forty four individuals had diabetic peripheral neuropathy (NDS of three or greater). Binary logistic regression analysis was performed, adjusting for the presence of diabetic retinopathy, age, sex, type of diabetes, duration of diabetes and HbA1c levels. RESULTS: Twenty-five per cent of individuals with diabetic peripheral neuropathy had abnormal FLV compared to 11 per cent of those with diabetes but no diabetic peripheral neuropathy and five per cent in the control group (p = 0.011). Fourteen per cent of individuals with diabetic peripheral neuropathy, 10 per cent without diabetic peripheral neuropathy and two per cent in the control group had abnormal GLV (p = 0.185). For every unit increase in the neuropathy disability score, the odds of having an abnormal FLV increased by a factor of 1.25 (p = 0.007), after adjusting for potentially confounding factors. Abnormal GCC FLV is an independent predictor of diabetic neuropathy, (odds ratio = 2.94, 95 per cent CI [1.16, 7.40], p = 0.023). CONCLUSION: Diabetic peripheral neuropathy is associated with abnormal GCC FLV at the macula, which is independent of diabetic retinopathy, age, sex, type of diabetes, duration of diabetes and HbA1c levels. An abnormality in GCC FLV is an independent predictor of diabetic peripheral neuropathy.

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.

Retinal thickness profile of individuals with diabetes.

PURPOSE: To examine the retinal thickness profiles of individuals with and without diabetic retinopathy (DR). METHODS: Full retinal thickness in the central zone, overall and hemisphere thicknesses of the parafovea and perifovea, ganglion cell complex (GCC) thickness and retinal nerve fibre layer (RNFL) thickness were assessed in 185 individuals using spectral domain optical coherence tomography (88 individuals with diabetes but no DR, 55 with DR, and 42 non-diabetic controls). The DR group comprised of 60% of participants with very mild non-proliferative diabetic retinopathy (NPDR) (representing microaneurysms only) and 40% with mild NPDR (hard exudates, cotton-wool spots, and/or mild retinal haemorrhages). Regression analysis was performed to determine the factors associated with retinal tissue thickness, taking into account, age, sex, presence of DR, duration of diabetes, HbA1c levels and type of diabetes. RESULTS: The mean (S.D.) of the overall parafoveal thickness was 306 (16) in the DR group and 314 (14) in the control group (p = 0.02). The mean (S.D.) of the superior hemisphere parafoveal thickness was 309 (16) in the DR group and 318 (14) in the control group (p = 0.02). The mean (S.D.) of the inferior hemisphere parafoveal thickness was 303 (17) in the DR group and 311 (15) in the control group (p = 0.02). There were no significant differences in retinal thickness between groups in the central zone (p = 0.27) or perifovea (p > 0.41). Neither the overall nor the hemisphere RNFL (p > 0.75) and GCC thickness (p > 0.37) were significantly different between the groups. Regression analysis revealed that parafoveal thickness in diabetic individuals was reduced in association with presence of DR (B = -5.9 µm, p = 0.02) and with advancing age (B = -4.5 µm, p = 0.004, for every 10 year increase in age) when adjusted for sex, duration of diabetes, HbA1c levels and type of diabetes. CONCLUSION: The inner macula is thinner in the presence of clinical signs of diabetic retinopathy and is compounded by advancing age. The influence of any macular oedema or that by cotton-wool spots could not be ruled out and may still confound these results.

Impact of simulated hyperopia on academic-related performance in children.

PURPOSE: To investigate the impact of simulated hyperopia and sustained near work on children's ability to perform a range of academic-related tasks. METHODS: Fifteen visually normal children (mean [±SD] age, 10.9 [±0.8] years; 10 male and 5 female) were recruited. Performance on a range of standardized academic-related outcome measures was assessed with and without 2.50 diopters of simulated bilateral hyperopia (administered in a randomized order), before and after 20 minutes of sustained near work, at two separate testing sessions. Academic-related measures included a standardized reading test (the Neale Analysis of Reading Ability), visual information processing tests (the Coding and Symbol Search subtests from the Wechsler Intelligence Scale for Children), and a reading-related eye movement test (the Developmental Eye Movement test). RESULTS: Simulated bilateral hyperopia and sustained near work each independently impaired reading, visual information processing, and reading-related eye movement performance (p < 0.001). A significant interaction was also demonstrated between these factors (p < 0.05), with the greatest decrement in performance observed when simulated hyperopia was combined with sustained near work. This combination resulted in performance reductions of between 5 and 24% across the range of academic-related measures. A significant moderate correlation was also found between the change in horizontal near heterophoria and the change in several of the academic-related outcome measures, after the addition of simulated hyperopia. CONCLUSIONS: A relatively low level of simulated bilateral hyperopia impaired children's performance on a range of academic-related outcome measures, with sustained near work further exacerbating this effect. Further investigations are required to determine the impact of correcting low levels of hyperopia on academic performance in children.

Simulated astigmatism impairs academic-related performance in children.

PURPOSE: Astigmatism is an important refractive condition in children. However, the functional impact of uncorrected astigmatism in this population is not well established, particularly with regard to academic performance. This study investigated the impact of simulated bilateral astigmatism on academic-related tasks before and after sustained near work in children. METHODS: Twenty visually normal children (mean age: 10.8 ± 0.7 years; six males and 14 females) completed a range of standardised academic-related tests with and without 1.50 D of simulated bilateral astigmatism (with both academic-related tests and the visual condition administered in a randomised order). The simulated astigmatism was induced using a positive cylindrical lens while maintaining a plano spherical equivalent. Performance was assessed before and after 20 min of sustained near work, during two separate testing sessions. Academic-related measures included a standardised reading test (the Neale Analysis of Reading Ability), visual information processing tests (Coding and Symbol Search subtests from the Wechsler Intelligence Scale for Children) and a reading-related eye movement test (the Developmental Eye Movement test). Each participant was systematically assigned either with-the-rule (WTR, axis 180°) or against-the-rule (ATR, axis 90°) simulated astigmatism to evaluate the influence of axis orientation on any decrements in performance. RESULTS: Reading, visual information processing and reading-related eye movement performance were all significantly impaired by both simulated bilateral astigmatism (p < 0.001) and sustained near work (p < 0.001), however, there was no significant interaction between these factors (p > 0.05). Simulated astigmatism led to a reduction of between 5% and 12% in performance across the academic-related outcome measures, but there was no significant effect of the axis (WTR or ATR) of astigmatism (p > 0.05). CONCLUSION: Simulated bilateral astigmatism impaired children's performance on a range of academic-related outcome measures irrespective of the orientation of the astigmatism. These findings have implications for the clinical management of non-amblyogenic levels of astigmatism in relation to academic performance in children. Correction of low to moderate levels of astigmatism may improve the functional performance of children in the classroom.

Simulated hyperopic anisometropia and reading, visual information processing, and reading-related eye movement performance in children.

PURPOSE: This study investigated the impact of simulated hyperopic anisometropia and sustained near work on performance of academic-related measures in children. METHODS: Participants included 16 children (mean age: 11.1 ± 0.8 years) with minimal refractive error. Academic-related outcome measures included a reading test (Neale Analysis of Reading Ability), visual information-processing tests (Coding and Symbol Search subtests from the Wechsler Intelligence Scale for Children), and a reading-related eye movement test (Developmental Eye Movement test). Performance was assessed with and without 0.75 diopters of simulated monocular hyperopic defocus (administered in a randomized order), before and after 20 minutes of sustained near work. Unilateral hyperopic defocus was systematically assigned to either the dominant or nondominant sighting eye to evaluate the impact of ocular dominance on any performance decrements. RESULTS: Simulated hyperopic anisometropia and sustained near work both independently reduced performance on all of the outcome measures (P < 0.001). A significant interaction was also observed between simulated anisometropia and near work (P < 0.05), with the greatest decrement in performance observed during simulated anisometropia in combination with sustained near work. Laterality of the refractive error simulation (ocular dominance) did not significantly influence the outcome measures (P > 0.05). A reduction of up to 12% in performance was observed across the range of academic-related measures following sustained near work undertaken during the anisometropic simulation. CONCLUSIONS: Simulated hyperopic anisometropia significantly impaired academic-related performance, particularly in combination with sustained near work. The impact of uncorrected habitual anisometropia on academic-related performance in children requires further investigation.

Apparent inferior rectus palsy with gaze-dependent sensory adaptations.

PURPOSE: This report presents a case of apparent congenital inferior rectus palsy notable for sensory adaptations that appeared to vary with direction of gaze. It is shown that readily available clinical tests and an understanding of the physiology of ocular motility can be used to help distinguish from differential diagnoses such as contralateral inferior oblique palsy or the more commonly seen Brown syndrome. CASE REPORT: A 20-year-old male optometry student reported strabismus that had been noted at birth and was diagnosed as Brown syndrome in childhood. The Parks three-step test showed primary gaze hypertropia that increased in left gaze but the "third step" (Bielschowsky head tilt test) was not successful in establishing the apparently correct diagnosis, which was later confirmed by a Hess screen. A proposed "fourth" step by Bajandas proved to be more accurate in this case of inferior rectus palsy. Sensory tests revealed adaptation patterns that varied with gaze direction and showed a cyclotorsional element. The patient reported being relatively unconcerned about his condition as he seemed to be able to voluntarily use a form of shallow suppression to reduce awareness of diplopic images. CONCLUSIONS: Although it is common to consider suppression and retinal correspondence status as hardwired and relatively constant for an individual patient, this case demonstrates that these sensory adaptations are likely to be far more complex and transitory. An understanding of both motor and sensory repercussions of ocular motility dysfunction assists differentiation between benign and sinister causes of nonconcomitant strabismus.

Longitudinal assessment of neuropathy in type 1 diabetes using novel ophthalmic markers (LANDMark): study design and baseline characteristics.

AIMS: Corneal nerve morphology and corneal sensation threshold have recently been explored as potential surrogate markers for the evaluation of diabetic neuropathy. We present the baseline findings of the 'Longitudinal Assessment of Neuropathy in type 1 Diabetes using novel ophthalmic Markers'(LANDMark) study. METHODS: The LANDMark study is a 4-year, two-site, natural history study of three participant groups: type 1 diabetes with neuropathy (T1W), type 1 diabetes without neuropathy (T1WO) and control participants without diabetes or neuropathy. All participants undergo a detailed annual assessment of neuropathy including corneal nerve parameters measured using corneal confocal microscopy and corneal sensitivity measured using non-contact corneal aesthesiometry. RESULTS: 76 T1W, 166 T1WO and 154 control participants were enrolled into the study. Corneal sensation threshold was significantly higher (i.e., sensitivity was lower) in T1W (1.0±1.1mbars) than T1WO (0.7±0.7mbars) and controls (0.6±0.4mbars) (p<0.001), with no difference between T1WO and controls. Corneal nerve fibre length was lower in T1W (14.0±6.4mm/mm(2)) compared to T1WO (19.1±5.8mm/mm(2)) and controls (23.2±6.3mm/mm(2)) (p<0.001). Corneal nerve fibre length was lower in T1WO compared to controls. CONCLUSIONS: The LANDMark baseline findings confirm a reduction in corneal sensitivity only in Type 1 patients with neuropathy. However, corneal nerve fibre length is reduced in Type 1 patients without neuropathy with an even greater deficit in Type 1 patients with neuropathy.

Review of guidelines for children's vision screenings.

The aim of children's vision screenings is to detect visual problems that are common in this age category through valid and reliable tests. Nevertheless, the cost effectiveness of paediatric vision screenings, the nature of the tests included in the screening batteries and the ideal screening age has been the cause of much debate in Australia and worldwide. Therefore, the purpose of this review is to report on the current practice of children's vision screenings in Australia and other countries, as well as to evaluate the evidence for and against the provision of such screenings. This was undertaken through a detailed investigation of peer-reviewed publications on this topic. The current review demonstrates that there is no agreed vision screening protocol for children in Australia. This appears to be a result of the lack of strong evidence supporting the benefit of such screenings. While amblyopia, strabismus and, to a lesser extent refractive error, are targeted by many screening programs during pre-school and at school entry, there is less agreement regarding the value of screening for other visual conditions, such as binocular vision disorders, ocular health problems and refractive errors that are less likely to reduce distance visual acuity. In addition, in Australia, little agreement exists in the frequency and coverage of screening programs between states and territories and the screening programs that are offered are ad hoc and poorly documented. Australian children stand to benefit from improved cohesion and communication between jurisdictions and health professionals to enable an equitable provision of validated vision screening services that have the best chance of early detection and intervention for a range of paediatric visual problems.

Refraction in children: a comparison of two methods of accommodation control.

PURPOSE: The prevalence of refractive errors in children has been extensively researched. Comparisons between studies can, however, be compromised because of differences between accommodation control methods and techniques used for measuring refractive error. The aim of this study was to compare spherical refractive error results obtained at baseline and using two different accommodation control methods-extended optical fogging and cycloplegia-for two measurement techniques-autorefraction and retinoscopy. METHODS: Participants included 25 school children aged 6 to 13 years (mean age, 9.52 ± 2.06 years). The refractive error of one eye was measured at baseline and again under two different accommodation control conditions: extended optical fogging (+2.00DS for 20 minutes) and cycloplegia (1% cyclopentolate). Autorefraction and retinoscopy were both used to measure the most plus spherical power for each condition. RESULTS: A significant interaction was demonstrated between measurement technique and accommodation control method (p = 0.036), with significant differences in spherical power evident between accommodation control methods for each of the measurement techniques (p < 0.005). For retinoscopy, refractive errors were significantly more positive for cycloplegia compared with optical fogging, which were in turn significantly more positive than baseline; whereas for autorefraction, there were significant differences between cycloplegia and extended optical fogging and between cycloplegia and baseline only. CONCLUSIONS: Determination of refractive error under cycloplegia elicits more plus than using extended optical fogging as a method to relax accommodation. These findings support the use of cycloplegic refraction compared with extended optical fogging as a means of controlling accommodation for population-based refractive error studies in children.

Wide-field assessment of the human corneal subbasal nerve plexus in diabetic neuropathy using a novel mapping technique.

To develop a rapid optimized technique of wide-field imaging of the human corneal subbasal nerve plexus. A dynamic fixation target was developed and, coupled with semiautomated tiling software, a rapid method of capturing and montaging multiple corneal confocal microscopy images was created. To illustrate the utility of this technique, wide-field maps of the subbasal nerve plexus were produced in 2 participants with diabetes, 1 with and 1 without neuropathy. The technique produced montages of the central 3 mm of the subbasal corneal nerve plexus. The maps seem to show a general reduction in the number of nerve fibers and branches in the diabetic participant with neuropathy compared with the individual without neuropathy.This novel technique will allow more routine and widespread use of subbasal nerve plexus mapping in clinical and research situations. The significant reduction in the time to image the corneal subbasal nerve plexus should expedite studies of larger groups of diabetic patients and those with other conditions affecting nerve fibers. The inferior whorl and the surrounding areas may show the greatest loss of nerve fibers in individuals with diabetic neuropathy, but this should be further investigated in a larger cohort.

Optimal image sample size for corneal nerve morphometry.

PURPOSE: Arbitrary numbers of corneal confocal microscopy images have been used for analysis of corneal subbasal nerve parameters under the implicit assumption that these are a representative sample of the central corneal nerve plexus. The purpose of this study is to present a technique for quantifying the number of random central corneal images required to achieve an acceptable level of accuracy in the measurement of corneal nerve fiber length and branch density. METHODS: Every possible combination of 2 to 16 images (where 16 was deemed the true mean) of the central corneal subbasal nerve plexus, not overlapping by more than 20%, were assessed for nerve fiber length and branch density in 20 subjects with type 2 diabetes and varying degrees of functional nerve deficit. Mean ratios were calculated to allow comparisons between and within subjects. RESULTS: In assessing nerve branch density, eight randomly chosen images not overlapping by more than 20% produced an average that was within 30% of the true mean 95% of the time. A similar sampling strategy of five images was 13% within the true mean 80% of the time for corneal nerve fiber length. CONCLUSIONS: The "sample combination analysis" presented here can be used to determine the sample size required for a desired level of accuracy of quantification of corneal subbasal nerve parameters. This technique may have applications in other biological sampling studies.