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Christopher J Lyons

Publications and source records attributed to Christopher J Lyons.

6 recordsLinked to original sources
PubMed2005

Ocular overelevation in adduction in craniosynostosis: is it the result of excyclorotation of the extraocular muscles?

PURPOSE: We sought to determine whether radiological evidence supports excyclorotation of the extraocular muscle cone as a cause of overelevation in adduction in children with craniosynostosis. METHODS: This was a retrospective case series of 40 patients with craniosynostosis. Ophthalmic findings were assessed for incomitant vertical strabismus in particular excessive elevation in adduction. Computed tomography and magnetic resonance imaging scans were reviewed. Those scans with adequate coronal imaging of their orbits to assess the position and angulation of the horizontal extraocular muscles were identified, and the degree of rotation of the muscles formally measured along with aged matched controls. These groups were analyzed for the association between presence of overelevation in adduction and degree of excyclorotation of the extraocular muscle cone. RESULTS: The identified updrift on adduction that mimics inferior oblique muscle overaction was present in 63% (25/40) of patients. Imaging that permitted accurate measurement of the muscles positions was available in 10 of the 40 patients. Of these 10, 8 had the updrift, and 7 of these 8 (88%) demonstrated more excyclorotation than their aged matched controls. Comparison of scan measurements of patients revealed a significant difference in degree of excyclorotation (mean difference = 16.2, 95% confidence interval 6.2-31.5; P = 0.006) between patients with and without excess elevation in adduction. CONCLUSION: Overelevation in adduction is significantly associated with excyclorotation of the extraocular muscle cone in children with craniosynostosis. We demonstrate a simple method to assess for the excyclorotation. Our findings support the importance of imaging of the orbits in these children before strabismus surgery.

Craniosynostoses↗
PubMed2005

"Cherry-red spot" or "perifoveal white patch"?

The color of the normal fovea, red in Caucasians, contrasts with the surrounding retina, whose colour is altered by accumulation of metabolic products, causing retinal pallor. In this photo-essay, we present the fundus photographs of 3 patients of different race, all with metabolic disease, each of whose fovea contrasts with the surrounding retina, and for whom the expression "cherry red spot" is not necessarily accurate. We suggest that the term "perifoveal white patch" describes this characteristic finding more accurately. We also discuss the pathological entities that may produce this striking appearance, along with its histological and anatomical basis.

Child↗
PubMed2005

Oculomotor nerve palsy in childhood.

BACKGROUND: The management of children with oculomotor nerve palsy is complicated by their variable presentation, amblyopia, potential loss of binocularity, and associated neurological disease. Our purpose was to evaluate the causes, neurological associations, treatment, and sensorimotor outcomes of a group of children who developed oculomotor nerve palsy. METHODS: We identified 18 children aged 14 years or younger, of whom 13 (72%) were less than 8 years old, through a retrospective record review of all children with oculomotor nerve palsy seen between January 1995 and January 2001 by one of the authors (C.J.L.). RESULTS: Congenital-onset oculomotor nerve palsy was the most frequent presentation, followed by traumatic, neoplastic, vascular, and migrainous or para-infectious etiologies. Pupil sparing was seen in 1 patient with neoplastic etiology. Primary aberrant regeneration was the presenting sign in a child with neurofibromatosis type 2. Amblyopia developed in 7 (39%) children and was successfully treated in 5 of the 7 (71%). Stereopsis was maintained in 6 (33%) children of whom 2 were within the amblyogenic age group. Six (33%) patients underwent strabismus surgery, and 3 of them (50%) achieved orthotropia and maintained stereopsis. INTERPRETATION: Children with oculomotor nerve palsy require neuroimaging. Their pupillary signs, unlike those of adults, are not helpful in differentiating compressive etiologies from other causes. Good visual acuity was obtained in children within the amblyogenic age group with appropriate occlusion therapy. Stereopsis was uncommon in children who developed third nerve palsy during the amblyogenic period; preservation of stereopsis was dependent either on rapid and complete recovery, or on the child's adoption of a compensatory head position.

Adolescent↗
PubMed2003

Presbyopia complicating pre-existing strabismus.

BACKGROUND: Presbyopia may affect pre-existing sensory adaptations or aggravate previously asymptomatic heterophoria. We describe the presentation, underlying problem and management of 11 patients with pre-existing strabismus or heterophoria who presented with new symptoms of double vision attributable to presbyopic change, an association not previously reported. METHODS: Patients with new strabismic symptoms attributable to presbyopia were recruited prospectively over a 1-year period. RESULTS: The 11 patients had had a recent decrease of accommodative amplitude that resulted in blurred vision at near with a breakdown of pre-existing heterophoria (2 patients), alteration of fixation pattern (6 patients), symptomatic alternating fixation (2 patients) or intolerance to correction owing to restrictive strabismus (1 patient). INTERPRETATION: At the onset of presbyopia, symptoms may be varied and subtle. Ophthalmologists and orthoptists should carefully determine the exact nature of the symptoms. Any pre-existing fixation pattern should then be established from the history, old photographs or suppression characteristics. Refractive or surgical management should be aimed at returning the patient to his or her long-standing sensory adaptation. Other important issues, such as incomplete correction of hypermetropia by refractive surgery and problems using bifocals with vertical restrictive strabismus, should be noted.

Accommodation, Ocular↗
PubMed2003

Conscious visual abilities in a patient with early bilateral occipital damage.

A 21-year-old male presented with occipital lobes that were extensively damaged by bilateral infarcts present at birth. The absence of the striate cortex was confirmed with anatomic and functional MRI and high-resolution EEG. His cortical visual impairment was severe, but he retained a remarkable ability to see fast-moving stimuli. Horizontal optokinetic nystagmus could be elicited from either eye. Resolution acuity was close to normal providing the patient was allowed to move his head and eyes. The direction of motion in random-dot patterns could be discriminated with perfect accuracy at speeds above 2 deg/s, and the patient reported that he could 'see' the motion at fast but not at slow speeds. This conscious residual vision for motion is known as Riddoch's phenomenon, but it has never been reported in the complete absence of the striate cortex. Functional neuroimaging revealed activation that was outside the motion-responsive regions of the extrastriate cortex. This case demonstrates remarkable plasticity in the human visual system and may have implications for understanding the functional organization of the motion pathways.

Adult↗