Cause Of Childhood Visual Impairment Research Articles

PACAP Is Protective in a Rat Model of Retinopathy of Prematurity.

The oxygen-induced retinopathy (OIR) is a well-established rodent model of retinopathy of prematurity (ROP), which is one of the most common causes of childhood visual impairment affecting preterm babies. Pituitary adenylate cyclase-activating polypeptide (PACAP) is known to have neuroprotective effects. Several studies have revealed the presence of PACAP and its receptors in the retina and reported its protective effects in ischemic and diabetic retinopathy. In this study, we investigated whether PACAP administration can influence the vascular changes in the rat OIR model. OIR was generated by placing the animals in daily alternating 10/50 oxygen concentrations from postnatal day (PD) 0 to PD14 then returned them to room air. Meanwhile, animals received PACAP or saline intraperitoneally or intravitreally from PD1 to PD8 or on PD11, PD14, and PD17, respectively. On PD19±1, the retinas were isolated and the vessels were visualized by isolectin staining. The percentage of avascular to whole retinal areas and the number of branching points were measured. Change in cytokine expression was also determined. Intravitreal treatment with PACAP remarkably reduced the extent of avascular area compared to the non- and saline-treated OIR groups. Intraperitoneal PACAP injection did not influence the vascular extent. Retinal images of room-air controls did not show vascular alterations. No changes in the number of vessel branching were observed after treatments. Alterations in cytokine profile after local PACAP injection further supported the protective role of the peptide. This is the first study to examine the effects of PACAP in ROP. Although the exact mechanism is still not revealed, the present results show that PACAP treatment can ameliorate the vascular changes in the animal model of ROP.

Childhood eye care services in South Darfur State of Sudan: Learner and parent perspectives

Purpose: Most causes of childhood visual impairment are either treatable or preventable. Eye health education plays an important role in reducing avoidable causes of visual impairment as well as to help ensure a healthy and educated community. The main objective of this study was to assess the Knowledge, Attitudes and Practices of the students and their parents on childhood eye services and barriers for accessing child eye care.Methods: The study was conducted in South Darfur State of Sudan between January and February 2015. Both quantitative and qualitative methods were used to collect data from eight secondary schools. Four schools for boys and four schools for girls were randomly selected from a list of 21 districts of South Darfur State and the Knowledge, Attitudes and Practices surveys were conducted with the students to collect quantitative data. In addition, seven focus group discussions were conducted with the children’s parents to collect qualitative data.Results: The majority (57.5%) of the students reported that they knew about refractive error; however, 33.07% reported never hearing about refractive error. About 70.3% of the respondents believed that uncorrected refractive error leads to visual impairment, 21% believed refractive error did not cause visual impairment and 30.5% reported that wearing spectacles was not effective in the treatment of refractive error. With regard to the information about eye healthcare, 88.1% of the participants reported they did not have enough information about eye care. The reported need for more information about prevention, treatment and symptoms was 34.0%, 31.4% and 17.5%, respectively. With regard to barriers, 80.6% of the students reported never having had their eyes tested. The most cited barriers were cost, fear of wearing spectacles and fear of an eye examination. In addition, 72.6% of students reported that their health insurance did not cover eye care services. Most (53.6%) of the parents believed that the cause of refractive error in children was poor nutrition. Common themes arising from the focus group discussions included parents reporting that they looked for traditional treatment for their children and preferring to receive child eye information from an eye specialist and through the television and radio. The most frequently cited barriers by the parents were high cost of the treatment, lack of eye care specialists, lack of awareness about child eye diseases and mistrust in eye care providers.Conclusion: The level of knowledge and practices about eye care and refractive error is low and perceptions about spectacles as a method for treatment for refractive error were fraught with misconceptions amongst students. There is a need for structured educational programmes to raise awareness regarding the effect and treatment modalities for childhood eye disease and visual impairment in order to address the barriers for accessing childhood eye care.Keywords: Children; school; eye care; spectacles; refractive error; knowledge;barriers; optometrist

Profile of Amblyopia in School going (5-15 years) Children at State Level Referral Hospital in Uttarakhand.

Amblyopia is one of the common causes of childhood visual impairment. The prevalence of amblyopia usually varies according to the age group of the studied population and the factors prevailing in that region. The upper limit of the critical time when amblyopia can develop is around eight years of age and it can be permanent if corrective measures are not taken in time. The purpose of study was to know the profile and pattern of amblyopia in children aged 5-15 years with refractive error in Uttarakhand and to compare it with national and regional (South Asian) studies. In the present retrospective cross-sectional study, 360 children from 5-15 yrs of age who attended the OPD during the period between September 2014 to February 2015, had undergone detailed Ophthalmic examination. The children having vision < 6/12 with out organic lesion were included in the study. The children with strabismus, previous ocular surgery and ocular diseases were excluded. Chi-Square test was done for statistical analysis (IBM SPSS Version 23). The percentage of amblyopia was 8.6% (n=31) with insignificant gender variation (p-value>0.05). Amblyopia due to astigmatism (combined) was in 41.93% (n=13) followed by Hypermetropia [32.25% (n=10)] and least in myopia [25.8% (n=8)]. In 51.61% cases age of presentation was 5-10 years while rest belonged to > 10 years of age. Binocular amblyopia was more (58.06%) then unilateral amblyopia (41.93%). Refractory errors are second most common cause of paediatrc amblyopia. Amblyopia and associated strabismus can have devastating psychosocial and economical fall outs. Our study emphasizes the need of visual screening of school children and prescribing them correct spectacles at appropriate time.

A Cross-sectional Study of Prevalence and Etiology of Childhood Visual Impairment in Auckland, New Zealand.

Childhood visual impairment has significant individual and socioeconomic costs with global differences in etiology and prevalence. This study aimed to determine prevalence, etiology, and avoidable causes of childhood visual impairment in New Zealand. Retrospective data analysis from a national referral center, the Blind and Low Vision Education Network New Zealand, Auckland. The World Health Organization Program for Prevention of Blindness eye examination records for visually impaired children, 16 years or younger, registered with the Auckland Visual Resource Centre, were included. Data analyzed included demographics, etiology, visual acuity, visual fields, educational setting, and rehabilitation plan. Charts of 340 children were examined, of which 267 children (144 blind, 123 low vision) were included in the analysis, whereas the remaining 73 charts of children with no visual impairment were excluded. The calculated prevalence of blindness and low vision was 0.05% and 0.04%, respectively, in the Auckland region. Principal causes of blindness affecting 91 children (63.9%) were cerebral visual impairment in 61 children (42.4%), optic nerve atrophy in 18 children (12.5%), and retinal dystrophy in 13 children (9.0%). The main potentially avoidable causes of blindness in 27 children (19%) were neonatal trauma, asphyxia in 9 children (33%), and nonaccidental injury 6 children (22%). This first report of prevalence for childhood blindness and low vision in New Zealand is similar to data from Established Market Economy countries. The leading causes of blindness are also comparable to other high-income countries; however, proportions of avoidable causes differ significantly.

Deprivation Amblyopia and Congenital Hereditary Cataract

Amblyopia is a neurodevelopmental disorder of vision associated with decreased visual acuity, poor or absent stereopsis, and suppression of information from one eye. Amblyopia may be caused by strabismus (strabismic amblyopia), refractive error (anisometropic amblyopia), or deprivation from obstructed vision (deprivation amblyopia). In the developed world, amblyopia is the most common cause of childhood visual impairment, which reduces quality of life and also almost doubles the lifetime risk of legal blindness. Successful treatment of amblyopia greatly depends on early detection and treatment of predisposing disorders such as congenital cataract, which is the most common cause of deprivational amblyopia. Understanding the genetic causes of congenital cataract leads to more effective screening tests, early detection and treatment of infants and children who are at high risk for hereditary congenital cataract.

Sweep visual evoked potential and visual development in optic nerve hypoplasia

Optic nerve hypoplasia (ONH) remains a leading cause of childhood visual impairment. Visual development in infancy and preverbal age in patients with ONH has not been well characterized to date. In this study, we assessed sweep visual evoked potential (VEP) measurements as indicators of early visual development and predictors of final recognition visual outcome in patients with ONH. We retrospectively studied 38 patients with clinically diagnosed ONH who had performed sweep VEP. Final recognition acuity was assessed with Snellen or HOTV letters, if patients were capable. Other factors assessed included presence of nystagmus, CNS malformations, pituitary involvement, and optic nerve size. Most patients had subnormal sweep VEP acuities compared to age-matched normals. VEP acuities reached a plateau by 20 months of age in patients with ONH compared to a plateau at 12 months in normal children, correlating well with recognition acuity performed at an older age. 59% of patients had acuity worse than 20/40, and 11% had acuity 20/200 or worse after 20 months of age. Sweep VEP measurements in ONH suggest a significant delay in visual development, but confirm that there is some improvement in vision until 20 months of age. Final visual acuity correlates with sweep VEP measurements, suggesting that sweep VEP may be used to predict outcomes at an early age. Sweep VEP measurements may be used clinically to provide parents with an accurate visual prognosis for children with optic nerve hypoplasia.

Prediction and treatment of ROP: Emerging strategies

Retinopathy of Prematurity(ROP) is a leading cause of childhood visual impairment and blindness in developed countries, and is increasingly prevalent in developing countries. Ablative therapy for Type 1 ROP usually allows favorable outcomes, but less destructive and preventative treatment strategies would be optimal. We need ways to predict early those infants who will develop ROP, particularly for locales where ophthalmologists are not readily available. Low IGF-1 levels and poor post-natal weight gain are important predictors in ROP development, and weight surveillance alone may help identify infants at highest risk of severe ROP development. We developed an algorithm (WINROP) that predicts significant ROP early (median time to development of ROP, 9 weeks, and treatable ROP, 8 weeks) with very high specificity and sensitivity. A multicenter trial to evaluate this method is underway, and we will discuss results to date and discuss expanding the use of this method in more US and world NICUs. Dietary supplementation has also been a topic of ROP research, and since composition of parenteral nutrition and breast milk plays an important role in brain and eye development, recognition of deficiencies with supplementation to normal levels could play an important role in ROP prevention. VEGF inhibitors for ROP treatment offer promise and will also be discussed, though current use in the US is limited to compassionate use or as part of a clinical trial such as BLOCK-ROP. The panel will discuss recent clinical research in these areas and how this information may be used in the clinical setting.

The neurovascular retina in retinopathy of prematurity.

The continuing worldwide epidemic of retinopathy of prematurity (ROP), a leading cause of childhood visual impairment, strongly motivates further research into mechanisms of the disease. Although the hallmark of ROP is abnormal retinal vasculature, a growing body of evidence supports a critical role for the neural retina in the ROP disease process. The age of onset of ROP coincides with the rapid developmental increase in rod photoreceptor outer segment length and rhodopsin content of the retina with escalation of energy demands. Using a combination of non-invasive electroretinographic (ERG), psychophysical, and image analysis procedures, the neural retina and its vasculature have been studied in prematurely born human subjects, both with and without ROP, and in rats that model the key vascular and neural parameters found in human ROP subjects. These data are compared to comprehensive numeric summaries of the neural and vascular features in normally developing human and rat retina. In rats, biochemical, anatomical, and molecular biological investigations are paired with the non-invasive assessments. ROP, even if mild, primarily and persistently alters the structure and function of photoreceptors. Post-receptor neurons and retinal vasculature, which are intimately related, are also affected by ROP; conspicuous neurovascular abnormalities disappear, but subtle structural anomalies and functional deficits may persist years after clinical ROP resolves. The data from human subjects and rat models identify photoreceptor and post-receptor targets for interventions that promise improved outcomes for children at risk for ROP.

Retinal coloboma: prenatal diagnosis using a new technique, the ‘virtual fetal eyeground’

Retinal coloboma is an important cause of childhood visual impairment and blindness. It may be isolated or associated with one of several syndromes. To our knowledge, prenatal diagnosis of the condition has only been reported previously using magnetic resonance imaging, in a small number of cases1. We report a case of fetal coloboma diagnosed prenatally using a new three-dimensional (3D) ultrasound technique, the ‘virtual fetal eyeground’. A 23-year-old primigravida was examined in our institution at 27 weeks after right fetal microphthalmia had been diagnosed at 22 weeks. A careful examination of both eyes with two-dimensional ultrasound imaging revealed a small notch on the bottom of the left eyeball (Figure 1), leading to suspicion of a small coloboma of the retina. We then performed a 3D transabdominal ultrasound examination using a new technique, the ‘virtual fetal eyeground’, to visualize the left retina. Two-dimensional ultrasound image of the left eye at 27 weeks, showing the small notch on the bottom of the eyeball (arrow) that led to suspicion of a coloboma of the retina. Using a Voluson E8 (GE Medical Systems, Zipf, Austria) equipped with a transabdominal 5–9-MHz probe, volumes of the entire eye were acquired in a frontal plane of the fetal face. After volume acquisition, surface rendering mode was applied and the ‘Magicut’ tool was used to ‘erase’ the frontal portion of the eyeball, enabling visualization of the entire retina in a manner similar to an eyeground examination after birth2. Using this technique, a ‘hole’ (or coloboma) in the central part of the retina at the level of the papilla measuring 2.6 mm × 2.1 mm was diagnosed (Figure 2a; a normal retina at the same gestational age is shown in Figure 2b). The diagnosis was confirmed by an ophthalmologic examination under anesthesia 1 month after birth (Figure 3). (a) Visualization of the fetal coloboma at the level of the papilla at 27 weeks using a new three-dimensional ultrasound technique, the ‘virtual fetal eyeground’, and (b) a normal retina visualized using the technique at the same gestational age. Ophthalmoscopic image of the retina with coloboma at 1 month after birth. Development of the eyes begins with the formation of the optic sulcus at 22 days' gestation in the region of the future diencephalon. The cranial neuropore closes on day 24 and by this time the optic primordia have developed into lateral evaginations of the neural tube, the optic vesicles. The distal face of the optic vesicle (retinal disc) invaginates into the expanded tip of the optic vesicle to form the optic cup on day 31, which is connected to the brain via the optic stalk. Blood vessels access the interior of the optic cup via a groove on its ventral surface, the choroid fissure. The lips of the choroid fissure fuse by day 37, and the persistence of a part of the choroid fissure may be a cause of colobomas. Colobomas may occur in different parts of the eyeball: the eyelid, iris, retina and optic nerve3-6. The ‘virtual eyeground’ technique permits visualization of the entire retina from 16 weeks' gestation onwards2. We believe it may have a role in the diagnosis of retinal injury in isolated microphthalmia, and of fetal syndromes7-9 involving abnormalities of the eye such as CHARGE and PHACE10-12. We are grateful to Professor D. Bremond-Gignac (of the Department of Pediatric Ophthalmology) for examining the infant after birth and providing the ophthalmoscopic image.

Prenatal magnetic resonance imaging of optic nerve head coloboma

Congenital optic nerve head coloboma represents an important cause of childhood visual impairment and blindness; it can be isolated or, more often, it can be associated with several syndromes. Ultrasound has limitations in depicting the posterior aspect of the fetal eye globe, so prenatal information about ocular coloboma are very scarce. The purpose of this paper was to report prenatal magnetic resonance (MR) imaging features of optic nerve head coloboma. MR imaging at 1.5 Tesla was based on multiplanar single-shot fast spin-echo T2-weighted 3-4 mm thick contiguous sections. Three fetal cases with optic nerve head coloboma and one with microphthalmos and colobomatous cyst are reported. Coloboma appeared as a focal bulging of ocular globe profile at the insertion of optic nerve. Prenatal MR imaging allowed an accurate diagnosis to be obtained.

Causes of childhood visual impairment and unmet low-vision care in blind school students in Ghana

The purpose of this study was to determine the causes of childhood visual impairment and blindness in students of a school for blind children, to determine how many students had some residual vision, and to evaluate any unmet low-vision care. A survey of students in the blind school was conducted in two parts in May-June and then October 2003. The sample consisted of 201 students who became blind before the age of 16. Information was obtained from student interviews, doctors' referral notes and ophthalmic examination of all students who consented. Students with residual vision had low-vision assessments. These investigations were supplemented with active participation of the investigators in Parent-Teacher Association meetings and focus group discussions with parents. One hundred and ninety-nine students consented and were recruited, whereas two declined. Ninety-six became visually impaired within their first year of life and 33 by the age of 5 years. Pathology of the cornea and then the lens were the commonest causes of blindness. One hundred and eight students were totally blind, whereas 87 (43.7%) had some residual vision and formed the target for the second part of the study. Fifty-one out of 77 of this target group who turned up for low-vision examination had useful residual vision by the World Health Organisation (WHO) low-vision examination chart. Spectacle magnifiers aided two students to read normal print at N5 and N8, respectively. Different visual aids would help enhance the residual vision in some of the others. Emotional trauma was apparent in parents and teachers. Children who became blind later in life remained in shock for a longer time and adapted less well to their visual impairment. Visual impairment in the population is not uncommon. Some causes are preventable. There is a significant unmet need for low-vision care, particularly amongst children in Ghana, and perhaps many countries in the West Africa subregion. It is hoped that the findings from this study will help spur sustained interventions.

P30.05: Fetal MRI and 2D ultrasound imaging of unilateral choanal atresia in case of progressive unilateral ventriculomegaly, hypertelorism and nasal hypoplasia

coloboma). It may be complete (when all ocular tissues are involved: optic nerve head, retina, choroid, iris, and lens) or incomplete. ONC represents an important cause of childhood visual impairment and blindness; moreover, it can be associated with several Mendelian and non-Mendelian syndromes (i.e. CHARGE, PHACE, etc.). Because of ultrasound limitation in depicting the posterior aspect of the fetal eye globe, ONC has not been reported so far during prenatal life. Patients and methods: Among about 250 fetal MR imaging cranial examinations performed during 2006 and 2007, we found three fetuses carrying ONC. The gestational age ranged between 20 and 32 weeks. Examinations were performed with a 1.5 T scanner, using 3–4-mm thick single-shot T2-wighted spin-echo sections. Results: In 2/3 cases ONC was associated with other cranial and extracranial malformations: CHARGE syndrome, and microcephaly respectively. In the other case only unilateral microphtalmos was associated. In two cases the ONC was bilateral. The ONC was depicted on coronal and sagittal sections as a cleft of the posterior aspect of the globe with small cystic bulging of the globe. Conclusions: Although the sensitivity of fetal MR imaging in detecting ONC remains to be determined, the prenatal diagnosis of ONC may have significant implications for counseling and it may prompt further investigations to rule out possible associated syndromic conditions.

Advances in the molecular genetics of ocular coloboma

Ocular coloboma is a developmental anomaly of the eye that results from incomplete closure of the optic fissure, occurring 5–7 weeks post conception. Congenital colobomata are important causes of childhood visual impairment and blindness. This defect typically affects the iris, cornea, ciliary body, zonules, retina, choroid and optic nerve. Colobomata can be seen in isolation and in combination with an impressive number of multisystem disorders. As yet, no effective treatment is available for this condition and management is only supportive. Based upon animal studies of coloboma, mendelian genetic disorders and chromosomal abnormalities, the molecular and genetic mechanisms that regulate optic fissure morphogenesis are now being discovered. Defining the genes and environmental factors involved in coloboma formation will aid in the development of potential therapies for patients with this malformation. This review explores the progress in understanding the clinical and molecular aspects of ocular coloboma.

Les pathologies neuro-visuelles chez l’enfant cérébrolésé: À propos de quatre cas

Cerebral visual impairment is one of the main causes of childhood visual impairment in developed countries. These disorders are often linked with pre- or perinatal hypoxic brain injuries. The patterns of brain injuries depend on the severity and duration of hypoxia and the child's age. In premature children, periventricular leukomalacia affects the optic radiations and the subcortical visual brain. In full-term newborn babies, chronic hypoxia leads to the damage of the visual cortex and acute hypoxia damages the basal ganglia. They recover from cortical blindness in variable ways. Visual dysfunction is characterized by fixation troubles, subnormal acuity (crowding), difficulty with perceiving visual fields, movements, depth, cognitive defects (agnosia of images, objects or faces, visuospatial disorders), ocular motility disorders (tonic gaze deviation, strabismus, nystagmus). Accompanying these cerebral injuries, there are accommodation defects and optic disk abnormalities that vary according to the gestational age at the time of hypoxia.

Descriptive epidemiology of infantile cataracts in metropolitan Atlanta, GA, 1968-1998.

Infantile cataract is an important cause of childhood visual impairment. Surgery before 6 weeks of age is recommended for optimal visual outcome. Description of the epidemiologic characteristics of cataracts is important for an improved understanding of the condition. To identify at-risk populations and facilitate successful treatment of patients with infantile cataracts. Infants with cataracts diagnosed in the first year of life were identified using the Metropolitan Atlanta Congenital Defects Program, a birth defects surveillance program with active methods of case ascertainment, for the years 1968-1998. Several factors were analyzed, including year of birth, sex, race, maternal age, plurality (single vs multiple gestation), gestational age, birth weight, laterality, seasonality, and age at diagnosis. A total of 199 infants with cataracts were identified, for a rate of 2.03 per 10 000 births. In 117 infants (59%), cataracts occurred as an isolated defect; in 43 infants (22%), cataracts occurred as part of a syndrome; and in 39 infants (20%), additional, unrelated, major birth defects were also present. Rates were higher for low-birth-weight infants (those weighing <1500 g; risk ratio [RR], 6.01; 95% confidence interval [CI], 3.83-9.43) and preterm infants (RR, 1.70; 95% CI, 1.21-2.40). Of the cases that occurred as an isolated defect, 38% were diagnosed after 6 weeks. This population-based study provides 31 years of data from a diverse US population and allows identification of risk factors for infantile cataracts. The finding that a number of infants with cataracts continue to have their conditions diagnosed after 6 weeks of age emphasizes the need for direct ophthalmoscopic examination of the red reflex in the newborn period to facilitate early detection and improve outcomes.

Prevalence and Causes of Childhood Blindness and Visual Impairment in Quranic Boarding Schools in Al-Gazira State of Sudan

Aim: This study aimed to determine the prevalence and causes of childhood blindness and visual impairment among Quranic boarding schools children in Al-Gazira state of Sudan. Materials and Methods: A total of 822 children were screened, and they distributed in 8 traditional Quranic schools. The study divided into two phases, the first one was designed to detect the visually impaired children, and in the second one, the affected children were investigated deeply through inner eye, refraction, and cover test examinations. Results: The findings indicated that the prevalence of childhood visual impairment (6/12 and worse binocularly) with the best correction was 12 (1.5%) in children of traditional Quranic boarding schools in Al-Gazira state of Sudan. The prevalence of visual impairment among children was increased with the age of children (P ≤ 0.001). The uncorrected refractive errors was the main cause of visual impairment which represented (36%) of impaired children followed by cataract (21.5%), corneal opacities (21%), optic nerve lesion (10.7%), retinitis pigmentosa (3.6%), glaucoma (3.6%), and squint (3.6%). Conclusion: The study concluded that the most causes of childhood visual impairment in traditional Quranic boarding schools in Al-Gazira state of Sudan were avoidable. Uncorrected refractive errors was a major cause of visual impairment among children; this pointed out the need for urgent a comprehensive childhood eye care plan to deliver eye care services for them, through cooperation between governmental, community stakeholders, and nongovernmental organization working in the prevention of childhood blindness.