Katherine J. Fray

Perinatal cortical and subcortical visual loss: Mechanisms of injury and associated ophthalmologic signs

PURPOSE To determine whether term and preterm injuries to the retrogeniculate visual system are associated with recognizable patterns of ophthalmologic abnormalities and whether these patterns can be attributed to cortical (gray matter) or subcortical (white matter) injury. DESIGN A retrospective case series. PARTICIPANTS One hundred children with clinical and neuroimaging signs of perinatal posterior visual pathway injury who were examined at Arkansas Childrens Hospital Eye Clinic between 1989 and 1999. METHODS We reviewed magnetic resonance images or computed tomographic scans from 50 children with cortical (predominantly or exclusively involving cortical gray matter) and 50 children with subcortical (predominantly or exclusively involving subcortical white matter) perinatal injury to the retrogeniculate visual system. Ophthalmologic abnormalities were analyzed retrospectively in each group. MAIN OUTCOME MEASURES Conjugate gaze deviation, type of strabismus, abnormal eye movements, and optic disc morphology. RESULTS Horizontal conjugate gaze deviation, exotropia, and a normal optic disc appearance were significantly more common in cortical than in subcortical visual loss. Tonic downgaze, esotropia, and optic nerve hypoplasia (with or without coexisting pallor) were significantly more common in subcortical than in cortical visual loss. CONCLUSIONS Perinatal cortical and subcortical visual loss produce differing profiles of ophthalmologic dysfunction. A reclassification of periventricular leukomalacia and other forms of retrogeniculate white matter injury as subcortical visual loss would increase diagnostic specificity.

The prevalence of strabismus in congenital nystagmus: the influence of anterior visual pathway disease.

PURPOSE To determine the influence of underlying visual system disorders on the risk of developing strabismus in children with congenital nystagmus. METHODS We retrospectively reviewed 82 cases of congenital nystagmus from a pediatric ophthalmology referral practice. RESULTS Strabismus was found in 50% of children with congenital nystagmus. The prevalence of strabismus was 82% in children with bilateral optic nerve hypoplasia, 53% in patients with albinism, 36% in children with congenital retinal dystrophies, and 17% in children with idiopathic congenital nystagmus. CONCLUSION The risk that a child with congenital nystagmus will have strabismus develop can be predicted from the nature of the underlying visual disorder.

Intermittent exotropia increasing with near fixation: a “soft” sign of neurological disease

Aim: To examine the association of distance-near disparity with neurological disease in children with intermittent exotropia. Methods: A retrospective analysis was performed of the medical records of all children with intermittent exotropia examined at the Arkansas Children’s Hospital between 1989 and 2002. The study group consisted of children with intermittent exotropia who had a near deviation that exceeded the deviation at distance by at least 10 prism dioptres. The control group consisted of children with intermittent exotropia who had a distance deviation greater than or equal to the deviation at near. The main outcome measure was the prevalence of neurological abnormalities in the study and control groups. Results: Among the 29 patients in the study group, 19 (66%) had a history of concurrent neurological abnormalities. Associated neurological conditions included developmental delay (10 patients), attention deficit disorder (four patients), cerebral palsy (four patients), history of intracranial haemorrhage (four patients), periventricular leucomalacia (three patients), seizures (two patients), cortical visual impairment (two patients), hydrocephalus (one patient), history of anoxic brain damage (one patient), history of encephalitis (one patient), and autism (one patient). Among the 37 patients in the control group, seven (19%) had a history of concurrent neurological abnormalities. The difference in the prevalence of neurological disease between the study group and the control group was significant (p = 0.0002). Conclusion: Intermittent exotropia increasing with near fixation is associated with neurological disease in children.

Surgical Management of Intermittent Exotropia With High AC/A Ratio

BACKGROUND A subgroup of patients with intermittent exotropia have a high AC/A ratio, which places them at risk for esotropia at near after surgical treatment of their distance deviation. METHODS A retrospective review of six patients with intermittent exotropia and a high AC/A ratio who were simultaneously treated with lateral rectus recessions to fully correct their exotropia at distance and placement of posterior fixation sutures on both medial rectus muscles in hopes of preventing an esotropia at near after surgery. RESULTS Despite the persistence of a high postoperative AC/A ratio as assessed by the gradient method, five of six patients achieved stable postoperative alignment at distance and near without bifocals. One patient required postoperative bifocal correction for intermittent esotropia at near. CONCLUSION In patients with intermittent exotropia and a high AC/A ratio, posterior fixation of the medial rectus muscles at the time of lateral rectus recessions enables the surgeon to fully correct the distance deviation and minimizes the risk of postoperative esotropia at near.

Fusional amplitudes: exploring where fusion falters.

Background and Purpose The stability of binocular vision depends on good fusional amplitudes, but the assessment of fusional amplitudes varies around the world. The author reviewed the literature on fusional amplitudes and surveyed international orthoptists on their assessment of fusional amplitudes. The purpose of the study was to determine whether or not there is variation in fusional amplitudes in normal subjects when looking at the role of examiner encouragement; the order of testing; the method of testing; and the subjects level of alertness. The preliminary results from this ongoing, prospective study are presented. Patients and Methods Using a modified crossover design study, the author prospectively assessed fusional amplitudes in fifty participants with normal eye exams who met inclusion criteria. The measurements were done in two separate sessions with each participant being randomized as to the order of fusional vergence testing. All participants were assessed without and with encouragement in the first session. In the second session, all were assessed at different testing distances. Results Convergence is significantly affected by encouragement and divergence is significantly reduced if assessed after convergence. Numbers were too small to get meaningful data on the effect of fatigue on final outcome measures. Conclusions We need to develop consistency in assessing fusional amplitudes and agree upon a standard of testing. Variables such as the order of testing, whether or not encouragement is given, and a persons level of alertness can affect the final outcome. Encouragement should be done especially when assessing convergence fusional amplitudes and divergence should be assessed prior to convergence. Finally, it is important to note a patients level of alertness during vergence testing, especially if they are feeling foggy on one visit and are alert on the next. By implementing these strategies into your assessment of fusional amplitudes, the examiner will know if a change in amplitudes is due to treatment effect or just testing method.

DVD--a conceptual, clinical, and surgical overview.

Dissociated vertical deviation (DVD) is a slow, disconjugate hypertropic deviation of a nonfixating eye. It is usually bilateral, asymmetrical, and often associated with congenital esotropia. The deviating eye elevates, abducts, and excyclotorts. This type of strabismus is often variable, making measurement and clinical quantification difficult. Specific knowledge of the mechanisms and characteristics of the dissociated deviation are required for proper assessment and effective treatment. There is currently no consensus on the mechanisms and pathophysiology of DVD. In this workshop, participants discuss the characteristics and most current methods for assessing and quantifying the deviation and explore the potential etiologies, clinical characteristics, and indications for surgical intervention and nonsurgical management of DVD.

How to Perform the Reversed Fixation Test

The reversed fixation test is a simple clinical test that was developed to visualize subtle dissociated deviations. In recent years, we have used this test to diagnose dissociated vertical divergence and dissociated horizontal deviation in the setting of complex strabismus. In this article, we describe our technique for performing and interpreting the reversed fixation test.

Neurodevelopmental outcomes with congenital ocular motor apraxia

The unique ocular motility dysfunction in isolated congenital ocular motor apraxia (COMA) is well characterised.1 Clinical findings include difficulty initiating horizontal saccades, horizontal head thrusting and relative preservation of vertical eye movements. In the European literature, COMA is referred to as Horizontal Saccadic Initiation Failure.2 Previous investigators have described the ocular motility dysfunction in patients with COMA.2 However, the neurodevelopmental profile of these patients has not been systematically investigated.3 The purpose of this study is to characterise the neurodevelopmental outcome in patients with COMA. We retrospectively analysed the medical records of all children diagnosed with COMA at Arkansas Childrens Hospital between 1993 and 2007. These patients were identified from a database that includes the diagnosis of all patients evaluated in the ophthalmology clinic during this time interval. Each patient had a complete ophthalmological examination as well as a developmental history, including questions regarding motor coordination, gait, language development, intellectual ability and school performance. The developmental status was determined from a review of the medical records from the ophthalmology clinic and …

Strabismus with a Twist: Pre- and Postoperative Torsion

Evaluating the torsional position of the eye is an important part of the examination of all patients with vertical strabismus. However, this assessment is often neglected in patients who do not specifically complain of torsional symptoms. The purpose of this paper is to review subjective and objective methods of evaluating the torsional position of the eye. In addition, clinical examples will be used to illustrate the importance of assessing torsion.

Fusional Amplitudes: Developing Testing Standards

ABSTRACT Purpose: The stability of binocular vision depends upon good fusional amplitudes, but the clinical assessment of fusional amplitudes varies around the world. The purpose of this study was to determine whether or not there is variation in the assessment of fusional amplitudes in normal subjects. The author looked at the testing distance, the order of testing, the role of examiner encouragement, and the subject’s level of alertness. Methods: In a prospective study using a modified crossover design, the author assessed fusional amplitudes in 99 subjects with normal eye exams. The measurements were done in two separate sessions on different days with each subject being randomized as to the order of fusional vergence testing. All subjects were assessed without and with encouragement in the first session. In the second session, all were assessed at different testing distances. Results: The author previously presented data on 50 subjects. In this expanded cohort, statistical significance was reached confirming the previous findings that convergence is significantly affected by encouragement, divergence is significantly reduced if assessed after convergence, and near amplitudes are significantly higher than distance amplitudes. Finally, there is a negative correlation between age and convergence break point. Conclusions: The results of this study demonstrate that divergence is significantly reduced if assessed after convergence in the subject with normal binocular function. Next, convergence is significantly affected by the use of encouragement. Measurements at near produced significantly higher results for all of the convergence and divergence tests. Finally, there is a significant negative correlation between age and convergence break point. We need to develop a standard of testing fusional amplitudes so there is consistency in the clinical assessment.