The inter-relationships between cerebral visual impairment, autism and intellectual disability.

From birth, vision guides our movement, facilitates social interaction and accords recognition and understanding of the environment. In children, vision underpins development of these skills, and is crucial for typical development. Deficits in visual processing may lead to impairment of cognitive, motor, and social development, placing children at risk of developing features of autism. Severe early onset visual dysfunction accords the greatest risk. Cerebral Visual Impairment (CVI) can lead to disorders of cognitive and social development that resemble Autism Spectrum Disorder (ASD). Similarly, children who appear primarily affected by cognitive and social developmental disorders, can manifest a range of visual and perceptual deficits that may be contributory to their disorder. This dual perspective highlights the need for links between impaired vision and neurodevelopmental disorders to be identified and acted upon by means of applying appropriate social and educational strategies. There is good evidence to show that targeted systematic screening for visual and perceptual impairments, and implementation of long-term management approaches, is now required for all at risk children.

Evaluation of the utility of hospital databases to provide data in assessing the quality of strabismus surgery.

AIMS AND BACKGROUND: Rates of re-operation, which may be related to an unsatisfactory surgical outcome, can provide a long-term index of the quality of strabismus surgery. This study aims to evaluate the utility of the Scottish Morbidity Records (SMR1) in determining nature and rates of re-operation for strabismus at the Royal Hospital for Sick Children (RHSC), Glasgow. METHODS: SMR1 data on strabismus surgery performed on children aged between 0 and 17 years at the RHSC, Glasgow, between January 2000 and March 2009 were analysed. RESULTS: In total, 1376 strabismus procedures were carried out on 1274 individuals. The median time between first and subsequent procedures was 19 months; the commonest reasons being under-correction or recurrence. The Kaplan-Meier rate of undergoing re-operation was 7.4% after 9 years with a 95% confidence interval of 5.4-9.9%. CONCLUSIONS: The SMR1 is a useful source of hospital-based and population data. With supplementation from parallel databases, routine administrative databases like the SMR1 can provide better quality data to inform practice.

Penetration of topical and subconjunctival corticosteroids into human aqueous humour and its therapeutic significance.

Topical and subconjunctival corticosteroids are some of the most effective and compelling treatment options in ocular inflammatory diseases. A systematic review of literature indexed by Ovid MEDLINE & EMBASE was performed up to December 2008. There are few studies on their aqueous penetration in human subjects. This review article discusses the penetration of different ocular corticosteroids into human aqueous humour along with the therapeutic implications on management of ocular surface diseases, immune-related corneal diseases, anterior uveitis and postoperative anti-inflammatory use. In the context of the paucity of well-constructed, prospective clinical trials comparing the efficacy of different corticosteroids, it provides guiding principles for the use of topical corticosteroids. Dexamethasone alcohol 0.1% and prednisolone acetate 1% are potent corticosteroids, but the latter achieves the highest aqueous concentration within 2 h and maintains higher levels for 24 h. Subconjunctival corticosteroids provide very high concentrations in the aqueous which maintain higher concentrations for longer periods.

Assessment of a computer-based treatment for older amblyopes: the Glasgow Pilot Study.

PURPOSE: There have been few viable alternatives to patching the better eye as a treatment of amblyopia for more than two centuries. The success of patching depends on compliance, which is problematic for up to 59% of children and their families. METHODS: This pilot study trialled the interactive binocular treatment (I-BiT) system as an alternative amblyopia treatment in 12 older amblyopes (6.1-11.4 years, median 8.2), who had not complied with or responded to occlusion. Virtual reality images were projected to each eye simultaneously via a headset during eight treatment sessions of 25-min duration. Outcome measures were changes in high- (HCVA) and low-contrast log MAR acuity (LCVA) at 1 week, 4 weeks and a final follow-up (3-18 months) after the final treatment. RESULTS: Sustained improvements in HCVA were observed in seven children (58%) and in LCVA in eight children (67%), including two for whom amblyopia was eliminated. Five children had visual acuities equivalent to 6/12 or better at least 6 months after stopping treatment, compared with one child prior to treatment. Significant improvements in HCVA occurred up to the fourth treatment; in LCVA to the seventh treatment. CONCLUSION: Sustained improvements in visual acuity were observed for 58% of this small group of children using the I-BiT system, despite prior failure with conventional treatment. This offers hope for a potential time-saving alternative to patching, in which compliance can easily be monitored, but the results need to be validated by means of a randomised controlled trial.

A visual skills inventory for children with neurological impairments.

Children with neurological impairments often have visual deficits that are difficult to quantify. We have compared visual skills evaluated by carers with results of a comprehensive visual assessment. Participants were 76 children with mild to profound intellectual and/or motor impairment (33 males, 43 females; age range 7mo-16y; mean age 5y 1mo [SD 4y 2mo]) who completed a visual skills inventory before attending a special vision clinic. The inventory included 16 questions about visual skills and responses to familiar situations. Responses were augmented by taking a structured clinical history, compared with visual evoked potential (VEP) and/or acuity card measures of visual acuity, and examined using exploratory factor analysis. Acuity ranged from normal to no light perception, and was positively associated with responses to individual questions. After excluding four uninformative questions, an association between the remaining questions and two significant independent factors was found. Factor 1 was associated with questions about visual recognition (e.g. 'Does your child see a small silent toy?') and these items were correlated with both the VEP and acuity card thresholds. Factor 2 was associated primarily with questions about visually mediated social interactions (e.g. 'Does he/she return your silent smile?'). Evaluation of visual skills in children with neurological impairment can provide valid information about the quality of children's vision. Questions with the highest validity for predicting vision are identified.

Negative ERGs in mucopolysaccharidoses (MPS) Hurler-Scheie (I-H/S) and Hurler (I-H)-syndromes.

The configuration and progression of the ERG in two children with mucopolysaccharidosis (MPS) I H/S (Hurler-Scheie syndrome) and MPS I H (Hurler syndrome) is described. Physical examination, biochemical analysis, ophthalmic examination and electroretinography were performed. The Hurler-Scheie patient (case 1) showed negative scotopic but normal photopic ERGs, which remained unchanged over 2 years. The Hurler patient (case 2) showed negative scotopic and photopic ERGs which did not alter after bone marrow transplantation (BMT). One year after BMT, further b-wave amplitude reduction had caused the ERGs to become more negative. The electronegative configuration of the ERGs suggests that, in these cases of MPS, the primary retinal abnormality in MPS I may be faulty synaptic transmission from photoreceptors to more proximal elements, deficient bipolar responsivity, or Muller cell disease. Further degradation with time suggests the defect to be progressive with BMT causing little or no improvement. In the Hurler-Scheie syndrome case, the defect appears to spare the cone system and to show little or no progression.

Congenital corneal anesthesia.

Congenital corneal anesthesia is a rare clinical entity that poses a diagnostic dilemma, particularly in the pediatric age group. The sensory deficit may be confined to the cornea, or extend to other divisions of the trigeminal nerve. The sensory deficit may occur as an isolated abnormality, as part of a complex neurological syndrome, or it may occur in association with multiple somatic abnormalities and congenital insensitivity to pain. This condition usually presents between the ages of 8 to 12 months. Poor vision, photophobia, conjunctival injection, and corneal ulceration in the absence of pain and distress in a child should alert the clinician to the possibility of anesthetic cornea. In the early stages of presentation, punctuate keratopathy is the main feature, which may progress to non-healing persistent corneal epithelial defects. This stage may progress to acute corneal lysis and perforation. In most patients, conservative approaches such as copious lubrication, prevention of self-harm and cautious use of bandage contact lenses are effective in preventing progressive corneal damage. Tarsorrhapy is effective in promoting epithelial healing and permanent lateral tarsorraphy may prevent further development of epithelial defects. Amniotic membrane graft may be considered in order to improve epithelial healing. Corneal grafts carry a poor prognosis. Accurate initial diagnosis, evaluation, and proper management are paramount to prevent visual loss due to long-term complications of corneal anesthesia. This review of the literature outlines the problems and approaches in diagnosis, evaluation, and management of this rare condition.

The symptomatic Pulfrich phenomenon can be successfully managed with a coloured lens in front of the good eye--a long-term follow-up study.

PURPOSE: Many visual symptoms originating from a spontaneous Pulfrich phenomenon can be alleviated by the provision of a tinted lens worn in front of the least affected eye. Here, we report on the long-term outcome of four patients who have been provided with a uniocular tinted spectacle or contact lens. METHODS: The case notes of four cases were reviewed. The review period was at least 5 years in all four cases. RESULTS: In all cases, visual symptoms and perceptual difficulties occurring from the spontaneous Pulfrich effect were completely eliminated over a period of many years. In one case, the relief has been sustained over a 20-year period. CONCLUSIONS: A uniocular tinted lens, or contact lens, provides immediate and lasting relief from the visual difficulties caused by the visual delay underlying the spontaneous Pulfrich effect.

Pathogenesis, clinical features and management of recurrent corneal erosions.

Recurrent corneal erosions (RCE) are common. They are characterised by repeated episodes of pain, difficulty in opening the eyes, watering, and photophobia resulting from poor epithelial adhesion. In the majority of patients with RCE, trauma is the initiating factor. Epithelial, stromal, and endothelial corneal dystrophies have all been described in association with RCE. Other causes that may lead to RCE include chemical and thermal injuries, previous herpetic keratitis, meibomian gland dysfunction, ocular rosacea, diabetes mellitus, Salzmann's nodular degeneration, band keratopathy, previous bacterial ulceration, kerato-conjunctivitis sicca, and epidermolysis bullosa. The conditions that are associated with RCE can be either primary or secondary depending on whether the basement membrane complex abnormality is intrinsic or acquired. Primary types tend to be bilateral, symmetrical and develop in multiple corneal locations. The pathogenetic mechanism of this disorder is related to poor adhesion of the corneal epithelium to the underlying stroma. Excessive matrix metalloproteinase (MMP) activity may play a role in the pathogenesis. Although the majority of patients will respond to simple measures such as padding and antibiotic ointment, RCE resistant to simple measures require approaches that are more elaborate. The common goal of these approaches is to encourage proper formation of adhesion complexes between the epithelium and the stroma. The use of long-term contact lenses, autologous serum eye drops, botulinum toxin, induced ptosis, oral MMP inhibitors, diamond burr polishing of Bowman's membrane have been reported with varying degree of success in treating RCE. Anterior stromal puncture with insulin needles or Neodymium : aluminium-yttrium-garnet may enhance the epithelial adhesion to the basement membrane by scar formation and success rates of up to 80% have been reported in the treatment of recalcitrant RCE. Excimer laser photo-therapeutic keratectomy (PTK) is now a well-established treatment modality for RCE and is being used both safely and effectively. Partial ablation of Bowman's layer with PTK gives a smooth surface for the newly generating epithelium to migrate and form adhesion complexes. The pathogenesis, clinical features, and management options of this common disorder are discussed in this review article.

Evolving concepts on the pathogenic mechanisms of aniridia related keratopathy.

Heterozygosity for PAX6 deficiency (PAX6+/-) results in aniridia. Corneal changes in aniridia-related keratopathy (ARK) include corneal vascular pannus formation, conjunctival invasion of the corneal surface, corneal epithelial erosions and epithelial abnormalities, which eventually result in corneal opacity and contribute to visual loss. Corneal changes in aniridia have been attributed to congenital deficiency of corneal limbal stem cells. The aim of this paper is to review the potential mechanisms that may underlie the pathogenesis of aniridia related keratopathy. Current evidence, based on clinical observations and an animal model of aniridia suggest that the proliferative potential of the corneal limbal stem cells may not primarily be impaired. The corneal changes in aniridia may be related to an abnormality within the limbal stem cell niche. The mechanisms underlying progressive corneal pathology in aniridia appear multi-factorial and include: (1) abnormal corneal healing responses secondary to anomalous extracellular matrix metabolism; (2) abnormal corneal epithelial differentiation leading to fragility of epithelial cells; (3) reduction in cell adhesion molecules in the PAX6 heterozygous state, rendering the cells susceptible to natural shearing forces; and (4) conjunctival and corneal changes leading to the presence of cells derived from conjunctiva on the corneal surface.

Visual acuity and the ability of the visually impaired to read medication instructions.

BACKGROUND/AIMS: Although medical information is often communicated in writing, little attention is given as to whether patients can read it--for example, the miniscule writing on the side of the medication bottles (equivalent to 6/6 reduced Snellen). The authors wished to determine a distance visual acuity threshold, using routine assessments of visual acuity (VA), beyond which patients are unable to read their instructions. METHODS: 180 patients, subgrouped according to the best line of Snellen acuity (from 6/9 to 6/60) achieved in either eye were recruited. Subjects were asked to read the printed manufacturer's instructions on the side of the drops box without magnification. RESULTS: Those subjects with best corrected VA of lower than or equal to 6/24 showed a significantly diminished ability to read the instructions on their eye drops bottles (p<0.001 for each comparison). When this group selected a font size of their choosing, the mode for preferred Arial font sizes were 16 for the 6/24 group, 18 for 6/36, and 22 for 6/60. CONCLUSION: This study documents the inability of patients with visual impairment to read the instructions on their bottle of eye drops. There is evidence of a distance VA threshold effect such that, although the majority of patients with 6/18 VA are able to read their instructions, patients whose VA is worse cannot. This latter group would benefit from a larger font size, a size of Arial 22 being sufficient. We recommend that all printed information for patients with visual acuities between 6/24 and 6/60 be printed in font Arial 22 or equivalent.

Congenital disorders of the optic nerve: excavations and hypoplasia.

The principal congenital abnormalities of the optic disc that can significantly impair visual function are excavation of the optic disc and optic nerve hypoplasia. The excavated optic disc abnormalities comprise optic disc coloboma, morning glory syndrome, and peripapillary staphyloma. Optic nerve hypoplasia manifests as a small optic nerve, which may or may not be accompanied by a peripapillary ring (the double ring sign). In addition, the optic disc cupping, which occurs as a sequel to some cases of periventricular leucomalacia, can arguably be classified as a type of optic nerve hypoplasia. All of these conditions can be unilateral or bilateral and can impair visual function mildly or severely. It is essential that children with poor vision due to any of these conditions are managed by treating refractive errors, giving occlusion therapy in selected cases, and optimising the conditions at home and at school in an attempt to ensure that impaired vision does not impede development or education.

Causes of blindness and visual impairment in the West of Scotland.

AIMS: To determine the overall reported incidence and causes of registrable blindness and visual impairment in the West of Scotland and any trends that have occurred in the previous 16 years since data from the same area were published. METHODS: Data for analysis were obtained from BP1 registration forms returned to the Resource Centre for the Blind serving the Strathclyde region in the West of Scotland between 1 April 1996 and 31 March 1997. RESULTS: A total of 1595 visually handicapped people were registered during the study year. Of these, 99 forms (6.2%) were excluded from further analysis because of insufficient information. The remaining 1496 completed BP1 Forms were in respect of 530 males and 966 females. Of these, 253 males and 450 females were legally blind (total 703 or 47.0%) and 277 males and 516 females were partially sighted (total 793 or 53.0%). The five leading causes of blindness, in decreasing frequency, were age-related macular degeneration (ARMD), glaucoma, diabetic retinopathy, myopic degeneration, and optic atrophy. ARMD and diabetic retinopathy were the most common causes of blindness in those over 65 years and persons of working age, respectively. CONCLUSIONS: In adults, cataract is no longer a significant cause of registrable visual impairment. The proportions of registrations owing to glaucoma, diabetic retinopathy, and myopia have not significantly changed since 1983 and the proportion owing to macular degeneration has increased. In children, congenital glaucoma, cataract, and corneal infection were no longer causes of registration, but impairment of vision caused by brain damage is now a significant contributor.

Association of binocular lower visual field impairment, impaired simultaneous perception, disordered visually guided motion and inaccurate saccades in children with cerebral visual dysfunction-a retrospective observational study.

The principal pathways serving higher visual function comprise the dorsal stream and the ventral stream. The dorsal stream runs between the occipital lobes and the parietal lobes and subserves the ability to process the whole visual scene and carry out visually guided movement. The ventral stream runs between the occipital lobes and temporal lobe tissue and primarily subserves visual recognition and memory. These tissues are susceptible to dysfunction in children with brain damage. We report a series of 40 children in whom damage to the brain has led to a common symptom complex affecting vision. Lower visual field loss was frequently elicited. This was associated with impaired ability to make accurate visually guided movement (particularly of the lower limbs) accompanied by impaired simultaneous perception, and in some cases, with inaccurate saccades and in others, impaired perception of movement. These features are consistent with parietal/dorsal stream dysfunction. Difficulty recognising faces and problems with route finding (which are ventral stream functions) were also present in a number of the children. These visual difficulties can be manifest in the presence of normal visual acuity. Recognition of these problems leads to understanding of the child's visual difficulties and facilitates adaptation of curriculum delivery at school.