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Biomedical subjects

M A Burdon

Publications and source records attributed to M A Burdon.

11 recordsLinked to original sources
PubMed1999

Dominant optic atrophy. Refining the clinical diagnostic criteria in light of genetic linkage studies.

OBJECTIVE: To describe the clinical findings and refine the clinical diagnostic criteria for dominant optic atrophy based on eight British families in which the diagnosis was confirmed by linkage analysis. DESIGN AND PARTICIPANTS: Case series; 92 subjects in 8 pedigrees had both eyes examined. INTERVENTION: Family members received a domiciliary examination based on best-corrected visual acuity, color vision using Ishihara and Hardy Richter Rand (HRR) plates, confrontation field testing using a red target, and optic disc evaluation using a direct ophthalmoscope. Genomic DNA was extracted from leukocytes or buccal mucosal cells and genotyped using 12 fluorescently labeled microsatellite markers from the region 3q27-q29. MAIN OUTCOME MEASURES: Subjects were classified clinically as definitely or possibly affected on the basis of the domiciliary examination before genetic analysis, and these results were compared with the haplotype analysis. RESULTS: Clinically, 43 subjects were identified as definitely affected, 4 as possibly affected, and 45 as unaffected. Visual acuity in affected subjects ranged from 6/6 to count fingers and declined with age. On genetic analysis, a haplotype was identified in each family, which was found in all definitely affected members but not in those regarded as unaffected. The four possibly affected individuals also bore the haplotype that segregated with the disease. CONCLUSIONS: Simple clinical tests are highly efficacious in diagnosing dominant optic atrophy. Contrary to accepted criteria, symptoms begin before the age of 10 years in only 58% of affected individuals. Visual acuity in affected subjects is highly variable. A mild degree of temporal or diffuse pallor of the optic disc and minimal color vision defects, in the context of a family with dominant optic atrophy, are highly suggestive of an individual being affected, even if the visual acuity is normal. This widens the generally accepted diagnostic criteria for this disease.

Adolescent↗
PubMed1997

Dominant optic atrophy, Kjer type. Linkage analysis and clinical features in a large British pedigree.

OBJECTIVES: To perform DNA linkage studies in an extensive 5-generation British pedigree with dominant optic atrophy and to validate the efficacy of domiciliary screening for affected members. METHODS: Family members received a domiciliary examination based on corrected visual acuity, color vision, visual field defects, and optic disc appearance; DNA linkage analysis was performed using 7 microsatellite markers on 3q27-qter. RESULTS: Based on the results of the ophthalmic examination, 15 members could be classified as definitely affected, 1 probably affected, and 25 unaffected. Two-point linkage analysis gave significant maximum lod scores at theta [corrected] = 0.00, with the markers D3S3669, D3S3590, and D3S3642. A haplotype segregating with the disease was identified in affected individuals, including the probably affected subject. Informative meioses defined the disease interval between markers D3S1601 and D3S1265. CONCLUSIONS: Domiciliary screening was effective in identifying all 16 affected members of a British family with dominant optic atrophy. The typical clinical features were present. The location of the OPA1 gene in this new British family seems to be in the 3q27-28 region and is the same as that reported in Danish, Cuban, and French families, suggesting no genetic heterogeneity in this disorder.

Adult↗
PubMed1997

Linkage studies in dominant optic atrophy, Kjer type: possible evidence for heterogeneity.

Dominant optic atrophy, Kjer type, is an autosomal dominant disorder causing progressive loss of visual acuity and colour vision from early childhood. The gene (OPA1) has variable expressivity, a penetrance of 0.98, and the locus has been localised to 3q28-29. We have genotyped nine British families with the disease using 12 polymorphic microsatellite markers from this region. Linkage and haplotype analysis shows the OPA1 gene to be located in a 2.3 cM interval between markers D3S1601 and D3S2748. One family showed no evidence of linkage with the chromosome 3 markers, suggesting for the first time that locus heterogeneity for this disease may exist, although exclusion for linkage is based on unaffected subjects. In addition, analysis of recombinants has enabled us to order the 12 markers along chromosome 3.

Adolescent↗
PubMed1996

The retina.

Prominent amongst last year's diverse papers on the retina were a study of the clinical manifestations of dominant cerebellar ataxia with pigmentary macular dystrophy, a review of the pathogenesis of carcinoma associated retinopathy, the Ischaemic Optic Neuropathy Decompression Trial, and a review of congenital optic disc anomalies. Ocular complications of several neurosurgical procedures were also reported during this period.

Cerebellar Ataxia↗
PubMed1995

Comparison of pars plana vitrectomy and scleral buckling for uncomplicated rhegmatogenous retinal detachment.

Retinal detachment surgery can now achieve a final reattachment rate in over 90% of cases. The operation of choice in most cases is that of external scleral buckling with or without drainage of subretinal fluid. However, in a minority of cases these techniques are difficult to apply either when the breaks are unseen due to media opacities or when the breaks are complex, eg, posterior, large, or multiple breaks at different distances from the ora. Improvements in the technique of pars plana vitrectomy for retinal detachment now offers us an alternative method for treating these difficult cases. Pars plana vitrectomy for retinal detachments with unseen or complex breaks has a final attachment rate of over 90%, is technically easier to perform than conventional surgery, and avoids the refractive and ocular motility problems associated with complicated buckles. For these reasons and despite the high risk of nuclear sclerosis in phakic eyes, a pars plana vitrectomy may be the preferred option in selected cases of primary retinal detachment.

Humans↗
PubMed1995

A survey of corneal graft practice in the United Kingdom.

A questionnaire designed to survey current corneal graft practice was sent to 498 consultant ophthalmologists in the United Kingdom. Three hundred and twenty-nine completed questionnaires (66%) were returned. Seventy per cent of these were from consultants who perform corneal grafts, of whom 36% had a specialist interest in corneal surgery. The survey found that most consultants preferred to perform corneal grafts on an inpatient basis with the patient under general anaesthesia. Agreement (> 80%) was also found in the following areas: use of a hand-held trephine, concurrent cataract surgery (if indicated), post-operative immunosuppression, and refraction to assess post-operative astigmatism. There was less agreement on the choice of donor material, use of tissue matching, donor-trephine size disparity, suture technique, relative timing of trabeculectomy surgery (if required), the management of intraocular lenses during surgery for pseudophakic bullous keratopathy, timing of discharge after surgery, use of prophylactic acyclovir, management of astigmatism, routine removal of all corneal sutures, and discharge of uncomplicated cases from routine follow-up.

Anesthesia, General↗
PubMed1994

Flash and pattern visual evoked potentials in the diagnosis and monitoring of dysthyroid optic neuropathy.

Flash and pattern visual evoked potentials were recorded in 8 patients (13 eyes) with dysthyroid optic neuropathy (DON), diagnosed using the American Thyroid Association classification. All were treated with systemic steroids, but 4 patients (6 eyes) also required orbital decompression. Flash VEP (P2) and pattern VEP (P100) were recorded prior to and 2 weeks after commencing steroid treatment or decompression. Fifteen patients with Graves orbitopathy but without DON, and 20 healthy subjects, acted as controls. Before treatment visual acuity was reduced in 10 eyes and visual fields were abnormal in 5, but the VEP was abnormal in all 13, with the group mean amplitude of P2 and P100 significantly less than controls, and the group mean P100 latency significantly greater than controls. After treatment with high-dose steroids or surgical decompression there were significant improvements in the group mean amplitude of P2 and P100, and significant reductions in P2 and P100 latency; however, individually, improvements in amplitude were more significant than improvements in latency. We conclude that the VEP to flash and pattern stimuli provides a useful diagnostic and monitoring tool in patients with DON, combining objectivity with quantitative analysis.

Adult↗
PubMed1993

Dissociated eye movements in craniosynostosis: a hypothesis revived.

A characteristic pattern of dissociated eye movements was observed in a large proportion of our patients with a variety of craniosynostosis syndromes. These anomalies simulate overaction of the inferior oblique and underaction of the superior oblique muscles which, however, cannot fully explain the abnormalities. In a number of cases, excyclorotation of the muscle cone was observed, with the upper pole of the eye tilted away from the midline. It is postulated that such excyclorotation of the eyes will lead to dissociated eye movements which can be explained on physiological grounds according to Hering's law. This paper presents a review of our patients and evidence to support this hypothesis.

Adolescent↗