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Biomedical subjects

P Riordan-Eva

Publications and source records attributed to P Riordan-Eva.

At least 19 recordsLinked to original sources
PubMed1998

Fast eye movement initiation of ocular torsion in mesodiencephalic lesions.

Three patients with episodic ocular torsion and skew deviation due to mesodiencephalic lesions were studied by using binocular three-dimensional scleral search coils. The conjugate ocular torsion (upper pole of each eye rotating toward the side of the brainstem lesion) was initiated by a torsional fast eye movement. During prolonged episodes, torsional nystagmus was also present. Cessation of the ocular torsion and skew deviation occurred by slow eye movements with exponentially decreasing velocities in 2 patients, and by multiple fast torsional movements in 1 patient. In 1 patient, the abnormal eye movements were temporally linked to dystonic movements in the limbs on the side opposite the brainstem lesion. The occurrence of skew deviation with conjugate ocular torsion in brainstem lesions has been attributed to functional asymmetry in vestibular pathways responsible for the slow-phase compensatory eye movement response to roll. In comparison, the findings in our patients show that in mesodiencephalic lesions conjugate ocular torsion with skew deviation may be generated by torsional fast eye movements, indicating activation of the burst cells of the rostral interstitial nucleus of the medial longitudinal fasciculus.

Adult↗
PubMed1997

Skew deviation following vestibular nerve surgery.

Eighteen consecutive patients undergoing vestibular nerve surgery underwent pre- and postoperative examination of ocular motility. Five patients developed a skew deviation following surgery, with the lower eye on the operated side and an incomitant pattern of deviation in all cases. Three patients experienced diplopia lasting from 1 day to 6 months. The magnitude of skew deviation was increased by head tilt away from the operated side in only 1 case. The development of skew deviation was not determined by preoperative ocular alignment or binocular function, or any particular type or pattern of vestibular disease. There was an association with large changes in ocular torsion and subjective visual vertical, which correlated with lesser degrees of canal paresis to preoperative caloric testing on the operated side. No patient developed a head tilt postoperatively. There is a gradation of responses to surgical vestibular deafferentation in humans, skew deviation only occurring in patients suffering marked changes in subjective visual vertical and ocular torsion.

Adult↗
PubMed1997

Autosomal recessive inheritance of hereditary motor and sensory neuropathy with optic atrophy.

Three siblings are reported with childhood onset hereditary motor and sensory neuropathy (HMSN) and adult onset optic atrophy. Electrophysiological studies showed an axonal neuropathy and dysfunction of the retinal ganglion cells or optic nerve. The presumed mode of inheritance is autosomal recessive. This is the second family in which autosomal recessive inheritance of HMSN and optic atrophy (HMSN type VI) has been described, and the first in which electrophysiological studies have been reported.

Aged↗
PubMed1997

Motion detection deficits in infantile esotropia without nystagmus.

PURPOSE: To investigate whether adults with infantile strabismus but without latent nystagmus have abnormalities of horizontal motion detection. METHODS: Eleven adult subjects with infantile esotropia but without latent nystagmus and 15 control subjects were required to detect the onset of motion and drift direction of a sinusoidal, spatial frequency grating that moved with linearly increasing velocity. The grating was presented monocularly in paracentral vision at an eccentricity of 16.5 degrees with a field size of 18 degrees. The contrast of the grating was just above contrast threshold for visibility. RESULTS: The mean velocity threshold for detection of motion was raised significantly in the patient group compared with the control group. Nine of the 11 subjects with infantile esotropia demonstrated directional asymmetry for the detection of motion. Thresholds were elevated more often when the grating was moving nasally in the squinting eye and temporally in the nonsquinting eye, and raised thresholds were more prevalent in the squinting eye. CONCLUSIONS: The findings indicate that in infantile esotropia, the presence of motion perception deficits are not always associated with the development of latent nystagmus. The predominance of nasally directed motion deficits in the squinting eye and temporally directed motion deficits in the nonsquinting eye was unexpected and may have been caused by abnormal development of cortical motion processing.

Adult↗
PubMed1996

MRI of the optic nerve in benign intracranial hypertension.

We investigated the MRI appearance of the optic nerve and its cerebrospinal-fluid-containing sheath in 17 patients with benign intracranial hypertension (BIH) and 15 normal controls. Using phased-array local coils, 3-mm coronal T2-weighted fat-suppressed fast spin-echo images were obtained with an in-plane resolution of < 0.39 mm. The optic nerve and its sheath were clearly differentiated. An enlarged, elongated subarachnoid space around the optic nerve was demonstrated in patients with BIH. High-resolution MRI of the optic nerve offers additional information which may be of value for diagnosis and in planning and monitoring treatment.

Adolescent↗
PubMed1996

Mitochondrial disorders in neuro-ophthalmology.

The pathogenesis of mitochondrial disorders relevant to neuro-ophthalmology has been further clarified by identifying and correlating to disease manifestations the three primary pathogenic mutations of Leber's hereditary optic neuropathy, and by correlating genetic, biochemical, and histochemical abnormalities in the mitochondrial myopathies and encephalomyopathies.

Humans↗
PubMed1996

Visual field loss following vitrectomy for stage 2 and 3 macular holes.

AIM: To describe the phenomenon of peripheral field loss following routine pars plana vitrectomy for stage 2 and 3 full thickness macular hole and to investigate the underlying mechanism. METHODS: Five patients, who reported peripheral field defects after apparently uncomplicated vitrectomy, posterior cortical vitreous peeling, and perfluoropropane (C3F8) gas tamponade, were studied retrospectively with slit-lamp biomicroscopy, automated and kinetic perimetry, fundal fluorescein angiography, focal electroretinography (ERG), and colour contrast sensitivity (CCS) testing. RESULTS: All five patients, who were between 50 and 73 years of age, reported an inferotemporal field defect following resolution of the intraocular gas bubble. In all eyes, the scotomata encroached to within 20 degrees to 30 degrees of fixation and to within 5 degrees to 15 degrees of the blind spot. In one eye, a partial altitudinal component was evident. All scotomata subsequently remained stable and three eyes developed subtle segmental nasal disc pallor and nerve fibre loss corresponding to the field defect. CCS testing revealed absent colour contrast in the scotomatous area, in the presence of a preserved focal quadrantic flash ERG, compared with normal CCS protan thresholds and focal ERGs in unaffected quadrants, indicating preserved outer retinal function in the area of the scotoma. CONCLUSIONS: These observations support the hypothesis that field defects occur as a result of retinal nerve fibre layer damage. It is proposed, on the basis of intraoperative observations and other evidence, that the most likely site of nerve fibre damage is at the nasal portion of the optic nerve rim or peripapillary retina, probably due to traction during cortical vitreous peeling.

Aged↗
PubMed1996

Abnormalities of torsional fast phase eye movements in unilateral rostral midbrain disease.

In a patient with a unilateral rostral midbrain lesion, three-dimensional scleral search coil eye movement recordings demonstrated slowing of ipsidirectional torsional fast phase eye movements without any abnormalities of torsional slow phases. On high-resolution MRI, the brainstem lesion localized to the area of the efferent pathways from the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF). This supports the experimental finding that unilateral inactivation of the riMLF results in a loss of ipsidirectional torsional fast phase eye movements and the hypothesis that there is lateralization of function throughout the torsional fast eye movement generating system.

Adult↗
PubMed1995

Mitochondrial DNA diseases: genotype and phenotype in Leber's hereditary optic neuropathy.

We have investigated 107 patients from 79 families with Leber's hereditary optic neuropathy (LHON), defined by the presence of one of the mitochondrial DNA (mtDNA) mutations at positions 11778 (60 families), 3460 (7), or 14484 (12). Only about 60% of the index patients had a history of similarly affected relatives. The ratios of affected male:female patients were 2.5:1 (11778), 2:1 (3460), and 5.7:1 (14484). Visual loss developed between the ages of 11 and 30 years in 69% with a range of 6-62 years, and this was not significantly different between mutation groups or males and females. Retinal microangiopathy was not detected in 36% of patients examined within 3 months of visual loss. A multiple sclerosis-like illness occurred in 45% of females with the 11778 mutation. Prognosis was better in the 14484 than the 3460 or 11778 patients, with useful recovery in 71% of patients. Good visual outcome was positively correlated with early age of onset (before 20 years). Unusual presentations, including young or old age at onset, caused diagnostic difficulties in this series, usually in the absence of a family history, which were resolved by mtDNA analysis. Recurrence risks to relatives could be derived from this series of families with genetically defined LHON.

Adolescent↗
PubMed1995

Antibodies to human optic nerve in Leber's hereditary optic neuropathy.

Mutations of mitochondrial DNA have now been identified in the majority of patients with Leber's hereditary optic neuropathy (LHON). However, these mutations do not explain all the clinical features of LHON, and other pathogenetic factors are likely to be operating. We have analysed serum from 69 LHON patients and their relatives, 58 controls and 14 patients with ischemic or compressive optic neuropathy. A significant proportion of LHON patients had circulating antibodies to tubulin protein. This finding supports the theory that autoimmunity may play some role in the pathogenesis of LHON.

Adult↗
PubMed1995

The clinical features of Leber's hereditary optic neuropathy defined by the presence of a pathogenic mitochondrial DNA mutation.

One hundred and seven patients from 79 families were defined as having Leber's hereditary optic neuropathy (LHON) by the presence of one of the mitochondrial DNA (mtDNA) mutations at positions 11778 (60 families), 3460 (seven families) or 14484 (12 families). Only half of the 11778 index patients had a history of similarly affected relatives; this proportion was higher with the 3460 (71%) and 14484 (100%) mutations. The ratios of affected male to female patients were 2.5:1 (11778), 2:1 (3460), and 5.7:1 (14484). Detailed clinical data were available for 79 patients from 55 families. Visual loss developed between the ages of 11 and 30 years in 69%, with a range of 6-62 years, and no significant differences between mutation groups or males and females. It was bilateral in all but two patients, to a median of counting fingers with a central scotoma, developing simultaneously in 22% and sequentially in 78%, with a median inter-eye delay of 8 weeks, and progressing in each eye over a period of 4-6 weeks. Nineteen patients had pain in an affected eye or on eye movements, and four experienced Uhthoff's phenomenon. Retinal microangiopathy was uncommon after 6 months from onset and was not detected in 36% of patients examined within 3 months of visual loss; the microangiopathy was particularly uncommon in the 14484 group. There was no difference in the overall visual outcome between the 11778 and 3460 groups with median final visual acuities of 1/60 and 3/60, respectively. Particularly severe visual loss occurred in one-third of women with the 11778 mutation, to vague perception of light or no perception of light in at least one eye. A multiple sclerosis-like illness was observed in 45% of females with the 11778 mutation. Prognosis was substantially better in the 14484 patients, with recovery to a final visual acuity of at least 6/24, in 71% of patients. Good visual outcome was strongly correlated with age at onset, all those with onset before 20 years having a final visual acuity better than 6/24 as opposed to only 2 out of 6 with later onset. Improvement in vision occurred as long as 4 years after onset. High alcohol and tobacco consumption, cranial or ocular trauma, young or old age at presentation, co-existing neurological disease, and recent childbirth with post-partum haemorrhage, all contributed to diagnostic difficulties in this series, usually in the absence of a family history. These problems were resolved by mtDNA analysis.

Adolescent↗
PubMed1995

High resolution magnetic resonance imaging of the anterior visual pathway in patients with optic neuropathies using fast spin echo and phased array local coils.

High resolution MRI of the anterior visual pathways was evaluated using frequency selective fat suppressed fast spin echo (FSE) sequences in conjunction with phased array local coils in patients with optic neuropathies. Fifteen normal controls and 57 patients were examined. Coronal T2 weighted fat suppressed FSE images were obtained in 11 minutes with an in plane resolution of 0.39 x 0.39 mm. The optic nerve and its sheath containing CSF were clearly differentiated. Central retinal vessels were often visible. In demyelinating optic neuritis and in anterior ischaemic optic neuropathy high signal within the nerve was readily delineated. Meningiomas and gliomas involving the optic nerve were precisely visualised both in the orbit and intracranially. Extrinsic compression of the optic nerves was readily visualised in carotid artery ectasia and dysthyroid eye disease. Enlarged subarachnoid spaces around the optic nerves were demonstrated in benign intracranial hypertension. High resolution MRI of the anterior visual pathway represents an advance in the diagnosis and management of patients presenting with optic neuropathy.

Adult↗
PubMed1995

Pedigree analysis in Leber hereditary optic neuropathy families with a pathogenic mtDNA mutation.

Eighty-nine index patients from 85 families were defined as having Leber hereditary optic neuropathy (LHON) by the presence of one of the mtDNA mutations at positions 11778 (66 families), 3460 (8 families), or 14484 (11 families). There were 62 secondary cases. Overall, 64% of index cases had a history of similarly affected relatives. The ratios of affected males to affected females were 3.7:1 (11778), 4.3:1 (3460), and 7.7:1 (14484). The 95th centile for age at onset of symptoms was close to 50 years in index, secondary, male, and female patients. There were no differences in the distributions of age at onset between different mutation groups, between index and secondary cases, or between males and females, apart from this being slightly later in all female patients than in male 11778 patients. There was no significant correlation between age at onset in index cases and that in their affected siblings or cousins. Heteroplasmy (< 96% mutant mtDNA) was detected in 4% of affected subjects (67%-90% mutant mtDNA) and in 13.6% of 140 unaffected relatives (< 5%-90% mutant mtDNA). Analysis of all pedigrees, excluding sibships < 50 years of age and index cases, indicated recurrence risks of 30%, 8%, 46%, 10%, 31%, and 6%, respectively, to the brothers, sisters, nephews, nieces, and male and female matrilineal first cousins of index cases. Affected females were more likely to have affected children, particularly daughters, than were unaffected female carriers. The pedigree data were entirely compatible with the previously proposed X-linked susceptibility locus, with a gene frequency of .08, penetrance of .11 in heterozygous females, and 40% of affected females being homozygous, the remainder being explained by heterozygosity and disadvantageous X inactivation.

Adolescent↗
PubMed1994

Orbital floor steroid injections in the treatment of uveitis.

Orbital floor steroid injections, like other posterior periocular injections, are advocated as a means of avoiding systemic immunosuppression in the management of uveitis in which there is significant posterior segment inflammation, but there are no published studies on their efficacy. The results of 54 orbital floor steroid injections to 33 eyes with uveitis were analysed. A positive response with an average duration of effect of 9 weeks was obtained after 48% of injections. These results compare favourably with the results of systemic immunosuppression in patients with comparable patterns of uveitis, thus establishing the efficacy of orbital floor steroid injections and their potential value when systemic immunosuppression needs to be avoided.

Adolescent↗