Assessment of the effects of myopic and hyperopic anisometropia on choroidal vascular structure in children using SS-OCTA.

OBJECTIVE: To compare large- and medium-sized choroidal vascularity and the choriocapillaris (CC) flow area in children with different refractive errors using swept-source optical coherence tomography angiography (SS-OCTA). METHODS: Forty-two anisometropic children were enrolled and divided into hyperopic anisometropia (HA) and myopic anisometropia (MA) groups. SS-OCTA was performed to analyse choroidal vascularity. Mean choroidal thickness (CT), choroidal vascularity volume (CVV), choroidal vascularity index (CVI) and CC flow area were compared between the two eyes. The inter-ocular differences between the two groups were also determined. RESULTS: Mean CT and CVV were highest in eyes with shorter axial lengths in both refractive groups, and the difference between the two eyes was positively correlated with the difference in axial length at the foveal region. Significant differences in the CVI in the MA group were only found in the parafoveal region. Inter-ocular differences in the CC were significantly reduced in eyes with longer axial lengths in the foveal and parafoveal regions of the HA and MA groups, respectively. Comparing inter-ocular differences, CC was significantly greater in the parafoveal region of the MA group than the HA group. CONCLUSIONS: All layers of choroidal vasculature were thinner in eyes with longer axial lengths in all groups. The inter-ocular CC difference was greater in the MA than in the HA group, with similar differences in axial length. This suggests that both medium-to-large choroidal vascular and choroidal capillaries may play a role in myopia development.

Quantitative assessment of eye movements using a binocular paradigm: comparison among amblyopic, recovered amblyopic and normal children.

BACKGROUND: To investigate the eye movement functions in children with amblyopia and recovered amblyopia by a binocular eye-tracking paradigm. METHODS: Eye movements of 135 pediatric subjects (age range: 4-14 years), including 45 amblyopic children, 45 recovered amblyopic children and 45 age-similar normal controls, were recorded under binocular viewing with corrected refractive errors (if any). The deviation of gaze positions relative to the target location was recorded as the mean from both eyes. Main outcome measures included fixation deviations (degree) along horizontal and vertical axes in the sustained fixation test (Fix-X, Fix-Y) and visually guided saccade test (Sac-X, Sac-Y), which were compared across the three groups and between each two groups. RESULTS: All the four deviations were significantly larger in the amblyopia group compared to the other two groups, indicating increased inaccuracy of sustained and post-saccadic fixations in amblyopia. However, there was no significant difference in deviations between recovered amblyopic children and normal controls. Repeated measures showed similar results overall and within each group. Mild to moderate amblyopes and severe amblyopes did not differ in the four deviations. No significant interaction was found between subject groups and clinical characteristics (age, refractive status, and anisometropia). CONCLUSION: Amblyopic children have poor eye movement functions with increased inaccuracy of sustained and post-saccadic fixations, which appear to be restored in children with recovered amblyopia. Binocular assessment of eye movements provides valuable indicators of functional recovery in amblyopia.

Assessment of stereopsis in pediatric and adolescent spectacle-corrected refractive error - A cross-sectional study.

PURPOSE: To assess the level of stereopsis in school children with spectacle-corrected refractive errors using Titmus fly and Randot stereo tests, evaluate the factors associated with the level of stereopsis, and determine the level of agreement between the two tests. METHODS: A cross-sectional study was done on 5- to 18-year-old school-children wearing spectacles for at least 1-month duration. Visual acuity was assessed using Snellen's visual acuity chart, and their spectacle correction being used currently was measured using an auto lensmeter. The level of stereopsis was assessed using Randot and Titmus fly stereo tests. Data were entered using Microsoft Excel and analyzed using IBM-SPSS version 20, Chicago, IL. The associations between stereopsis and type of refractive error, visual acuity, age, and gender were analyzed. An agreement between Randot and Titmus fly test was done using Kappa statistics. RESULTS: A total of 222 children (101 boys and 121 girls; mean age 13 years) were assessed. Astigmatism was the most prevalent refractive error (60.4%), followed by myopia (24.8%) and hypermetropia (1.4%). Thirty children (13.5%) had anisometropia. All hyperopes had normal stereopsis. Children with spherical myopia had better stereopsis, followed by astigmatism and anisometropia in the same order (P = 0.036). Children with anisometropia ≤1.5 D had better stereopsis than anisometropia more than 1.5 D. Stereopsis was also found to have no correlation with the age and visual acuity at the time of testing or the age at which the child first started wearing spectacles. Stereopsis values obtained from Randot and Titmus fly stereo tests showed moderate agreement with Kappa value 0.581. CONCLUSION: Anisometropia and astigmatism are the most critical factors determining the level of stereopsis in refractive errors.

The agreement between the Irvine 4 diopter prism test and assessment of ocular fixation in microtropia with identity.

Microtropia describes a primary ocular deviation of less than 10 prism diopters associated with harmonious anomalous retinal correspondence and reduced stereopsis. It is routinely accepted that children with microtropia are less likely to achieve equal vision following occlusion therapy than those with bifoveal fixation. The most commonly used methods of diagnosing a microtropia are the 4 diopter prism test (4∆PT) and assessment of ocular fixation. This study examines the agreement between the two tests. One hundred and twelve typically developing children without a manifest strabismus who were able to undertake a linear visual acuity test and had two or more lines of anisoacuity following refractive adaption to their full cycloplegic correction underwent assessment of the 4∆PT and ocular fixation along with their routine orthoptic examination. One hundred and twelve children (46 boys and 66 girls) attending the Orthoptic department who fitted the above criteria were included in the analysis. The mean age at examination was 6 years. 80.3% had anisometropia of at least 1.25 diopters. The 4∆PT indicated a microtropia in 74 cases, whereas assessment of fixation indicated a microtropia in 68 cases. In 88 cases (78.6%), the results of the two tests agreed. Analysis found only moderate agreement between the two tests (k = 0.540 (CI 0.379-0.700)). Logistic regression analysis comparing those children where the two tests agreed with those where they disagreed found no difference in the level of anisoacuity (p = 0.7823), degree of anisometropia (p = 0.9385), the vision in the worst eye (p = 0.5260), the refractive error in the "worst" eye (p = 0.865), or the age at the time of testing (p = 0.4485) between the two groups. When assessing for a microtropia, it was found that not all children who elicit a central suppression response on the 4∆PT are found to be fixing eccentrically and vice versa. This could potentially have implications for the treatment of their amblyopia. It is important not to rely on just one test at one time to make the diagnosis of microtropia. Rather, if one or other test indicates a microtropia the first time they are attempted, this should be reassessed regularly as treatment progresses and certainly before treatment is stopped and suboptimal visual acuity is accepted.

Assessment of Choroidal Vascularity and Choriocapillaris Blood Perfusion in Anisomyopic Adults by SS-OCT/OCTA.

Purpose: To explore the association of choroidal vascularity and choriocapillaris blood perfusion with myopic severity in anisomyopes. Methods: Refractive error, axial length (AL), and other biometric parameters were measured in 34 anisomyopic young adults. Macular choroidal thickness (ChT) and choroidal vascularity, including total choroidal area (TCA), luminal area (LA), stromal area (SA), and choroidal vascularity index (CVI), were determined from swept-source optical coherence tomography (SS-OCT) vertical and horizontal B-scans. The percentage of choriocapillaris flow voids (FV%) was obtained from en face SS-OCT-angiography. Results: The spherical equivalent refraction (SER) was -3.35 ± 1.25 diopters in the more myopic eyes and -1.25 ± 1.17 diopters in the less myopic eyes (P < 0.001). The interocular difference in SER was highly correlated with that in AL (P < 0.001). The macular ChT, TCA, LA, and SA were smaller in the more myopic eyes than in the less myopic eyes in both vertical and horizontal scans (all P < 0.001). Importantly, the CVIs in vertical and horizontal scans were smaller and the FV% was greater in the more myopic eyes (P < 0.05). In vertical scans, the interocular difference in CVIs was correlated with that in the SER, AL, and ChT (all P < 0.05). The interocular difference in FV% was correlated with that in SER, AL, and vertical and horizontal ChTs (all P < 0.05). Conclusions: Choroidal vascularity and choriocapillaris blood perfusion were lower in the more myopic eyes of anisomyopic adults. These changes were correlated with the severity of myopia and choroidal thinning, indicating that choroidal blood flow is disturbed in human myopia.

The assessment of anterior and posterior ocular structures in hyperopic anisometropic amblyopia.

BACKGROUND: The aim of this study was to examine the relationship or differences in ocular structures of amblyopic eyes compared to fellow eyes in children and young adults with hyperopic anisometropic amblyopia. MATERIAL/METHODS: Hyperopic participants with anisometropic amblyopia, defined as the presence of best-corrected visual acuity differences of at least 2 Snellen lines and 1.5 diopters between amblyopic and fellow eyes, were studied. Using the IOL Master, Pentacam Scheimpflug imaging and Spectralis optical coherence tomography, the axial length, corneal curvature, and anterior chamber depth (ACD), as well as the thickness of the cornea, peripapillary retinal nerve fiber layer (RNFL), and macula, were compared between children and young adults and between their amblyopic and fellow eyes. RESULTS: In 53 participants with hyperopic anisometropic amblyopia, there were significant differences in the anterior corneal curvature, ACD and axial length between the amblyopic and fellow eyes of all the patients. The mean central macular thickness in the amblyopic eyes was significantly thicker (P=.001) in the group aged 5 to 12 years; however, this was not the case in the group aged 13 to 42 years. There was no significant difference in average RNFL thickness in either group. CONCLUSIONS: We found significantly greater mean central macular thickness in anisometropic amblyopic eyes among participants aged 5 to 12 years, but not among those who were older. Similarly, the interocular differences in axial length parameters seemed to be related to the central macular thickness differences between the amblyopic and fellow eyes in the younger group.

Results of a pediatric vision screening program in western South Dakota.

BACKGROUND: South Dakota is one of eight states that do not require any vision screening for children. This study describes the results of the first children's vision screening program in the state. METHODS: Children ages 6 months to 12 years were screened using the SPOT photoscreener by lay volunteers as part of the Northern Plains Eye Foundation's Western South Dakota Children's Vision Screening Initiative (CVSI). Referral criteria were based on the recommendations of the manufacturer. Data was stratified by age group, sex, and percentage of children referred for hyperopia, myopia, astigmatism, anisocoria, anisometropia, and ocular misalignment. The cost benefit of amblyopia treatment in South Dakota was also calculated. RESULTS: Screenings were completed on 4,784 children from August 2012 to May 2014 with 62 excluded due to age. Mean age of the 4,722 (2,373 females) subjects was 6 years 7 months. Overall, the SPOT device referred 563 (11.9 percent) children. There was no significant difference in referral rate based on sex (p = 0.598). Children aged 73-144 months had the highest referral rate (12.2 percent) and children aged 12-30 months had the lowest referral rate (7.9 percent). The suspected reasons for referral based upon the screenings were as follows: 371 (7.9 percent) astigmatism, 24 (0.5 percent) ocular misalignment, 101 (2.1 percent) anisometropia, 135 (2.9 percent) myopia, 36 (0.8 percent) hyperopia, and 16 (0.3 percent) anisocoria. CONCLUSIONS: The SPOT photoscreener yielded an acceptable referral rate of 11.9 percent. This study represents an effective model for pediatric vision screening in South Dakota.

Stimulus characteristics affect assessment of pupil defects in amblyopia.

PURPOSE: Amblyopes do not reliably show relative afferent pupillary defects with full-field stimulation, but amblyopia has cortical involvement; hence, stimuli that engage cortex may be able to reveal pupil defects in amblyopes. METHODS: Pupillary responses were acquired with a binocular infrared pupillometer (RAPDx, Konan Medical USA, Irvine, CA) from 15 amblyopic subjects (anisometropic and small-angle strabismic) and 10 age-matched control subjects. Stimuli were a full-field white flash (330 cd/m) or a small (4 degrees) annulus at one of three contrast levels (0.3, 0.6, and 1.8) on a dim background (6.2 cd/m). Stimulus duration was 100 milliseconds, and the interstimulus duration was 2000 milliseconds. RESULTS: In all four stimulus conditions, the difference in percent contraction amplitude for right versus left eye stimulation was more variable across amblyopes than across control subjects. Amblyopic eyes did not show a specific deficit for the full-field flash. However, the mid-contrast (0.6) annulus stimulus revealed a deficit in the amblyopic eye, whereas the size of the deficit did not correlate with the type or depth of the amblyopia. CONCLUSIONS: Targets of appropriate pattern, brightness, and contrast that select for cortical contributions to the pupil response may be useful for eliciting pupil defects in amblyopic patients. Pupil analysis in this population could prove useful for diagnostic or prognostic value, for example, to determine which amblyopes will respond best to treatment.

Upper disparity limit after LASIK.

We evaluate the effect of the emmetropization technique LASIK (laser-assisted in situ keratomileusis) on stereoscopic vision. For this, we used a mirror stereoscope to measure the upper disparity limit D(max) before (with best correction) and after LASIK for 30 patients. The results show that the upper disparity limit declines from 41.1 min of arc on average to 31.3 min of arc after LASIK, being significant in 83% of the patients. This deterioration is significantly correlated with an increase in the postsurgical interocular differences in higher-order aberrations, corneal asphericity, and presurgical anisometropia. New ablation algorithms should minimize interocular differences in order to improve binocular visual performance.

The effect of axial length on ocular blood flow assessment in anisometropes.

BACKGROUND: Pulsatile ocular blood flow (POBF) assessment measures the choroidal circulation and therefore provides data with diagnostic value in certain ocular diseases, such as glaucoma. The technique assumes a constant pressure-volume relationship. The current study investigated the effect of axial length on POBF from subjects with axial anisometropia. Ocular blood supply in the ophthalmic artery was also determined using colour Doppler ultrasonography. METHODS: Thirty-one normal, anisometropic subjects were recruited, whose ages ranged from 20 to 34 years. They had axial anisometropia (expressed by spherical equivalent) of at least 2 D. After Goldmann tonometry, the POBF of each eye was measured in a supine posture by one examiner, followed by a measurement of the blood flow velocity in the ophthalmic artery using colour Doppler ultrasonography in the same posture by another examiner. There was a 10 min rest between the two techniques. All the measurements were made at around the same time to eliminate any effect from diurnal variation. RESULTS: The mean anisometropia (expressed by spherical equivalent) was 3.89 +/- 1.96 D and the mean inter-ocular axial length difference was 1.49 +/- 1.00 mm. The anisometropia and axial length were significantly different between the two eyes (paired t-tests: p < 0.001). However, the intra-ocular pressure was similar between the two eyes (paired t-test: p = 0.41). The POBF was significantly lower in the eye with the longer axial length (459.3 microL min-1) than the fellow eye (590.8 microL min-1), paired t-test: p < 0.001. The pulse amplitude was also significantly lower in the eye with the longer axial length (1.61 mmHg) than the fellow eye (1.89 mmHg), paired t-test: p < 0.001. However, the blood flow velocity from colour Doppler ultrasonography did not demonstrate any significant difference between the two eyes (paired t-test: p > 0.05). CONCLUSIONS: The POBF and pulse amplitude were found to be reduced in the eye with the longer axial length but colour Doppler ultrasonography did not show any significant difference. This suggests that a new pressure-volume relation should be considered in deriving POBF. Practitioners should measure the axial length in POBF assessment.

A survey of pediatric visual assessment by optometrists in New South Wales.

BACKGROUND: The importance of early vision care in the prevention and treatment of amblyopia is clear from an abundance of literature on visual development. Optometrists possess the necessary skills to detect and manage amblyogenic factors and thus have an important role to play in paediatric visual assessment and management. The present study investigates the role that optometrists in New South Wales are taking in paediatric vision care and the methods and strategies used in this role. METHODS: Questionnaires were sent to 400 optometrists practising in New South Wales; 179 completed questionnaires were returned. RESULTS AND DISCUSSION: Our findings reveal a number of associations between practice characteristics (such as location) and the management of paediatric patients. In general, practitioners in rural locations, in full-time practice or self-employed were more likely to treat patients and less likely to refer them elsewhere than those in city locations, in part-time practice or employed by others. In addition, our findings suggest the possibility of a changing pattern of collaboration between optometrists and ophthalmologists in the management of paediatric patients.

Atendimento a portadores de visäo subnormal: estudo retrospectivo de 317 casos / A retrospective study of 317 cases of low vision

A eficiência no uso do resíduo visual é de suma importância para pessoas portadoras de visäo subnormal (VSN). Atualmente, observa-se um crescente empenho de profissionais da área de saúde e educaçäo especial, tanto no sentido de minimizar os severos atrasos do desenvolvimento, bem como melhorar a utilizaçäo da visäo residual. O uso indiscriminado do termo cegueira tem frequentemente dificultado o reconhecimento das necessidades do paciente deficiente visual desencorajando-o a usar o potencial de visäo que ainda possui. Em alguns casos esses indivíduos säo treinados para usarem apenas o tato e a audiçäo. Os autores analisaram os prontuários de pacientes portadores de visäo subnormal, considerando idade, sexo e patologias encontradas nos primeiros 317 pacientes atendidos no Departamento de Visäo Subnormal, enfatizando a importância do precoce atendimento oftalmológico especializado