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.

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.

Peripheral retinal dysfunction in patients taking vigabatrin

OBJECTIVE

To assess the wide-field multifocal electroretinogram (WF-mfERG) for assessment of retinal function in vigabatrin-treated patients.

METHODS

Thirty-two adults who had taken vigabatrin for at least 3 years for localization-related epilepsy underwent WF-mfERG, ERG, logMar visual acuity and color vision evaluation, Humphrey visual field analysis (static perimetry), and funduscopy. The group was matched with a cohort of patients who had never received vigabatrin. Results were compared with a normative data set (120 drug-free controls) with respect to potential bilateral abnormalities in response timing.

RESULTS

There were no significant differences between groups in visual acuity or color vision testing. Of the vigabatrin patients, 19 (59%) had bilateral visual field defects compared to none of the controls. Using WF-mfERG, all patients on vigabatrin with visual field defects showed abnormalities (100% sensitivity) and only 2 of the 13 patients without a field defect showed retinal abnormalities (86% specificity).

CONCLUSIONS

WF-mfERG may be useful for detecting retinal pathology in patients taking vigabatrin. The majority of previous reports based on subjective testing may have underestimated the prevalence of peripheral retinal toxicity related to the drug.

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.

Cognitive vision, its disorders and differential diagnosis in adults and children: knowing where and what things are

As ophthalmologists we need a basic model of how the higher visual system works and its common disorders. This presentation aims to provide an outline of such a model. Our ability to survey a visual scene, locate and recognise an object of interest, move towards it and pick it up, recruits a number of complex cognitive higher visual pathways, all of which are susceptible to damage. The visual map in the mind needs to be co-located with reality and is primarily plotted by the posterior parietal lobes, which interact with the frontal lobes to choose the object of interest. Neck and extraocular muscle proprioceptors are probably responsible for maintaining this co-location when the head and eyes move with respect to the body, and synchronous input from both eyes is needed for correct localisation of moving targets. Recognition of what is being looked at is brought about by comparing the visual input with the "image libraries" in the temporal lobes. Once an object is recognised, its choice is mediated by parietal and frontal lobe tissue. The parietal lobes determine the visual coordinates and plan the visually guided movement of the limbs to pick it up, and the frontal lobes participate in making the choice. The connection between the occipital lobes and the parietal lobes is known as the dorsal stream, and the connection between the occipital lobes and the temporal lobes, comprises the ventral stream. Both disorders of neck and extraocular muscle proprioception, and disorders leading to asynchronous input along the two optic nerves are "peripheral" causes of impaired visually guided movement, while bilateral damage to the parietal lobes can result in central impairment of visually guided movement, or optic ataxia. Damage to the temporal lobes can result in impaired recognition, problems with route finding and poor visual memory. Spontaneous activity in the temporal lobes can result in formed visual hallucinations, in patients with impaired central visual function, particularly the elderly. Deficits in cognitive visual function can occur in different combinations in both children and adults depending on the nature and distribution of the underlying brain damage. In young children the potential for recovery can lead to significant improvement in parietal lobe function with time. Patients with these disorders need an understanding of their deficits and a structured positive approach to their rehabilitation.

Measurement of optic nerve sheath diameter by ultrasound: a means of detecting acute raised intracranial pressure in hydrocephalus

AIM

To evaluate the utility of measuring the optic nerve sheath diameter in children with shunted hydrocephalus, suspected of having raised intracranial pressure.

METHODS

23 children with shunted hydrocephalus were examined, six had well controlled ICP, 17 however manifested symptoms suggestive of intracranial hypertension. A clinical history was taken from all patients and their parents or carers. The shunt valve was examined clinically, and signs of raised intracranial pressure were sought. Ultrasound examination was performed in both eyes to measure the optic nerve sheath diameters 3 mm behind the globe. These measurements were compared with control data obtained from 102 children who attended the radiology department for unrelated renal ultrasound examination.

RESULTS

Control data suggested that the upper limit of normal for optic nerve sheath diameter is 4.5 mm (measured 3 mm behind the globe) in patients over 1 year of age, and 4.0 mm in children less than 1 year of age. Those patients with functioning ventriculoperitoneal shunts had a mean optic nerve sheath diameter of 2.9 (SD 0.5) mm; those with raised intracranial pressure had a mean optic nerve sheath diameter of 5.6 (0.6) mm (p<0.0001). These results confirm that optic nerve sheath diameters in excess of the control data are strongly suggestive of raised intracranial pressure.

CONCLUSION

The evaluation of the optic nerve sheath diameter is a simple non-invasive procedure, which is a potentially useful tool in the assessment and monitoring of children with hydrocephalus suspected of having raised intracranial pressure.

Cerebral visual impairment in children

Much of the brain is devoted to vision. Damage causes visual problems ranging from profound impairment, to cognitive visual problems only. A child with cerebral blindness may have intact perception of movement. The principal cognitive visual pathways comprise the dorsal and the ventral streams. The dorsal stream runs between the occipital lobes (which process incoming visual data), the posterior parietal lobes (which process the whole visual scene and give attention to component parts), the motor cortex (which facilitates movement through the visual scene) and the frontal cortex (which directs attention to chosen parts of the visual scene). The ventral stream runs between the occipital lobes and the temporal lobes (which enable recognition of people and objects, facilitate route finding and serve visual memory). Damage to these pathways disrupts these functions in a variety of combinations. This paper reviews cerebral visual impairment in children, the differential diagnosis and the management.

Spatial localization in esotropia: does extraretinal eye position information change?

PURPOSE

To investigate the accuracy of spatial localization in children with a specific type of convergent strabismus, fully accommodative esotropia.

METHODS

Two groups of children, with right and left fully accommodative esotropia, respectively, pointed at targets located centrally and eccentrically on a computer touchscreen without being able to see their hands. The size and the direction of the horizontal pointing responses were recorded under two conditions: when their eyes were aligned (wearing spectacles) and when they were squinting (not wearing spectacles). A group of children without strabismus but with hypermetropia were assessed as controls.

RESULTS

For both fully accommodative groups, the pointing responses to the central target shifted in the direction of the nonsquinting eye when deviations were manifest. No difference was found for the eccentric targets. No difference was found for the hypermetropia group with any target.

CONCLUSIONS

These results are consistent with an alteration in the extraretinal eye position information (efference copy, extraocular muscle proprioception, or both) that is used in spatial localization.

Reduced accommodative function in dyskinetic cerebral palsy: a novel management strategy

A 9-year-old boy with dyskinetic cerebral palsy secondary to neonatal encephalopathy is described. He presented with blurring of near vision which had begun to impact on his school work. Objective assessment of accommodation showed that very little was present, although convergence was almost normal. The near-vision symptoms were completely removed and reading dramatically improved with the provision of varifocal spectacles. Varifocal lenses provide an optimal correction for far, intermediate (i.e. for computer screens), and near distances (i.e. for reading). Managing this type of patient with varifocal spectacles has not been previously reported. It is clearly very important to prescribe an optimal spectacle correction to provide clear vision to optimize learning.

Periventricular leukomalacia: an important cause of visual and ocular motility dysfunction in children

The immature visual system in infants born preterm is vulnerable to adverse events during the perinatal period. Periventricular leukomalacia affecting the optic radiation has now become the principal cause of visual impairment and dysfunction in children born prematurely. Visual dysfunction is characterized by delayed visual maturation, subnormal visual acuity, crowding, visual field defects, and visual perceptual-cognitive problems. Magnetic resonance imaging is the method of choice for diagnosing this brain lesion, which is associated with optic disk abnormalities, strabismus, nystagmus, and deficient visually guided eye movements. Children with periventricular leukomalacia may present to the ophthalmologist within a clinical spectrum from severe cerebral visual impairment in combination with cerebral palsy and mental retardation to only early-onset esotropia, normal intellectual level, and no cerebral palsy. Optimal educational and habilitational strategies need to be developed to meet the needs of this group of visually impaired children.

Transorbital optic nerve sheath ultrasonography in normal children

AIM

Early diagnosis of acute intracranial hypertension is essential to enable prompt, optimal treatment. The optic nerve sheath diameter (ONSD) is increased in raised ICP and there has been recent interest in the use of ultrasound to diagnose and indirectly monitor raised ICP by ONSD measurement. The advantages of the technique include its non-invasiveness, wide availability, portability, low cost and the absence of ionizing radiation. This prospective study was designed to establish the range of normal values for ONSD in infants and children up to 15 years of age.

PATIENTS AND METHODS

One hundred and two children attending the hospital for other reasons were recruited to the study. Three measurements of the ONSD were taken for each eye, 3 mm behind the optic nerve head using a 7 MHz sector probe.

RESULTS

The range for ONSD was 2.1-4.3 mm, mean 3.08 (SD 0.36). There were no significant differences on ONSD measurement between boys and girls (P = 0.59) or between right and left eyes (P=0.66). When the data were grouped and analysed, a correlation between increasing age and increasing ONSD was seen (r2=0.48), with the greatest increase occurring in the first 2 months of life.

CONCLUSION

Using the technique described here, our results suggest that an ONSD of greater than 4 mm in infants less than 1 year, and 45 mm or greater in older children, should be regarded as abnormal.

Effect of oral administration of vitamin C on human aqueous humor ascorbate concentration

AIM

To study oral administration of vitamin C on human aqueous humour ascorbate concentration.

METHODS

High performance liquid chromatography (HPLC) coupled with electrochemical detector (ECD) was used. The effect of oral administration of various doses of ascorbic acid, 0 (control), 1.0, 1.5, 2.0, 3.0, and 5.0 g, on its concentration in aqueous humour, obtained from volunteer cataract patients was studied.

RESULTS

The concentration of ascorbic acid in aqueous humour of control group (without administration of vitamin-C tablet or drug containing ascorbic acid was (254 +/- 119) mg.L-1. This study revealed that the administration of 2.0 g of ascorbic acid saturate the aqueous humour and further increase in the dose (3.0 g and 5.0 g) did not increase its concentration in aqueous humour, although its concentration was increased in plasma.

CONCLUSION

Oral administration of 2.0 g of Vc is sufficient to saturate the aqueous humour where it may be helpful in controlling the intra-ocular pressure.

Evidence of cognitive visual problems in children with hydrocephalus: a structured clinical history-taking strategy

Damage to the occipital cortex in children can result in many complex disorders of cognitive visual function. A series of clinical questions, developed from the specific problems of a cohort of children with cortical visual impairment, was asked of the parents of 200 children with no history of cerebral pathology, aged 5 to 12 years. One hundred and ninety-two parents gave reliable consistent responses. The results show a progressive improvement in performance with age, culminating in few 11- and 12-year olds having frequent problems, apart from 8% having frequent difficulty with orientation in new surroundings and 2% having problems with simultaneous perception tasks. The parents of 52 children (aged 5 to 17 years) with shunted hydrocephalus were then asked the same set of questions. Evidence of cognitive visual problems was identified in 27 of these children of whom 16 manifested multiple difficulties. The disabilities identified by our study comprised problems with: shape recognition, simultaneous perception, perception of movement, colour perception, orientation, object recognition, and face recognition. The range, nature, and combinations of these disorders are presented in this paper.

Prognostic value of flash visual evoked potentials in preterm infants

This paper investigates the prognostic value of flash visual evoked potentials (VEPs) recorded in preterm infants at birth and at term age with respect to severe neurological outcome. Flash VEPs were recorded in 81 preterm infants at birth (i.e. <35 weeks' gestation) and repeated in 56 of these infants at term age. The preterm infants were assigned to either a healthy or at-risk subgroup based on clinical birth factors. Normal ranges of flash-VEP latencies, amplitudes, and number of components present were obtained from the subgroup of healthy preterm infants and from 68 term infants tested postnatally. The flash-VEP results of the entire preterm group were compared with the normal ranges and any abnormalities noted. Seven preterm infants in the at-risk group died, six of whom had abnormal flash VEPs before term age. Of the five infants from the at-risk group diagnosed with cerebral palsy (CP), three had abnormal flash VEPs before term age. Thus the sensitivity and specificity of the flash VEP with respect to survival was 86% and 89% respectively, and with respect to the development of CP was 60% and 92%. The abnormal features of the flash VEP associated with adverse outcomes comprised a delayed N3 component before term age and the absence of a positive component (P2) at term age.

Evolution of a form of pure alexia without agraphia in a child sustaining occipital lobe infarction at 2 1/2 years

The progress of cognitive visual dysfunction over an 8-year period of a child who sustained bilateral occipital-lobe infarctions at the age of 2 1/2 years is described. She survived with normal intelligence and went on to attend mainstream school. She manifested many features of cognitive visual impairment and, in particular, developed a form of pure alexia without agraphia. She achieved some letter-by-letter reading but no sight vocabulary development, including to her own name. She learned to write imaginatively employing phonetically true spelling but cannot read what she has written. Her progress and the difficulties encountered during the management of her condition are discussed in this first case report of the evolution of pure alexia without agraphia in childhood. The features of this syndrome in the developing child who has never developed the capacity to read are contrasted with that seen in affected adults.

An inner city preschool visual screening programme: long-term visual results

AIMS

The aim of this study was to investigate the long-term outcome of the treatment of amblyopia as a sequel to preschool screening, which has not hither-to been described.

METHODS

All patients originally referred from a preschool screening programme were recalled for examination by letter. 255 patients were reviewed at least 4 years after discharge of which 88 were definitely amblyopic at presentation and 107 were not amblyopic at presentation and were used as controls.

RESULTS

79% of the amblyopes improved or maintained visual acuity after discharge but this was reduced to 42% after an age induced increase (estimated from the controls) was compensated for. The mean drop in visual acuity in the amblyopic eyes which deteriorated was 0.23 (SD 0.15) logMAR units. Stepwise multiple linear regression showed that the best single predictor of post-discharge deterioration in visual acuity was the improvement in visual acuity seen during treatment (R2 = 19%). Eccentric fixation at time of follow up (increasing R2 to 47%) and good presenting acuity (further raising R2 to 57%) contributed additional information, and were both associated with greater post-discharge deterioration in visual acuity.

CONCLUSIONS

The majority of amblyopes who attended for follow up maintained or improved their visual acuities after discharge. Those patients who demonstrated deterioration of their amblyopia had usually improved well during the programme and were often fixating eccentrically at follow up.

Clinical characteristics of microtropia--is microtropia a fixed phenomenon?

BACKGROUND/AIMS

Microtropia is believed to be a static condition, in which accepted achievable levels of vision are those of 6/12-6/9 maximum, with the inability to achieve "normal" levels of stereopsis. The aim of this paper was to present the results of treatment of 30 consecutively presenting primary microtropes, and assess their outcomes using a more active treatment strategy than that conventionally used.

METHODS

Visual acuity, stereoacuity, fixation, and the presence of a central suppression scotoma were assessed in all patients before, during, and after treatment, which comprised wearing maximum refractive correction, and an occlusion strategy aiming for equal visual acuity.

RESULTS

Equal visual acuity of 6/5 Snellen was achieved in 43% of the 30 patients, while 87% achieved 6/9 Snellen or better visual acuity in the microtropic eye. Stereoacuity of better than 60" of arc was attained in 37%, and foveal fixation on visuscopy in 55%. The treatment outcome was not affected by the patient's age, initial visual acuity, or the amount of anisometropia. A change in the patient's diagnosis was noted in 50%, with nine patients recovering completely.

CONCLUSIONS

The results show that microtropia is not static. Equal 6/5 vision is attainable, as is high grade stereoacuity. The pattern of fixation may change during treatment and elimination of the microtropia is possible in some cases. There is a requirement for management protocols to be changed in order to treat this condition more effectively.

Recovery in microtropia: implications for aetiology and neurophysiology

AIMS/BACKGROUND

The basis of binocular single vision in microtropia remains a matter of contention. This paper discusses the implications of recovery, in a group of primary microtropes following treatment, in relation to current concepts on the aetiology of the condition and proposed retinocortical correspondence.

METHODS

Nine previously untreated primary microtropes whose condition resolved, were reviewed in detail to assess the patterns of change in retinal correspondence, uniocular fixation, stereoacuity, and visual acuity in response to treatment.

RESULTS

Anomalous retinal correspondence (ARC), a central scotoma, reduced or absent stereoacuity, amblyopia, and uniocular eccentric fixation were present in all patients before treatment. Following treatment, all cases attained normal retinal correspondence (NRC), elimination of the central scotoma, stereo acuity levels of between 20 and 40 seconds of arc, 6/5 Snellen visual acuity in both eyes, and foveal fixation in both eyes.

CONCLUSION

A hypothesis is put forward that for the patients described, a period of normal development is likely to have preceded the onset of microtropia, during which the retinocortical "foundations" for NRC were established. Precise pairing of foveo-foveal receptive fields was not abolished by the presence of amblyopia and a central scotoma, but this relation was temporarily suspended and binocular single vision was sustained via the neural substrate of paired receptive fields over a wide retinocortical area.