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Biomedical subjects

J M Olver

Publications and source records attributed to J M Olver.

11 recordsLinked to original sources
PubMed1992

Recovery of anterior segment circulation after strabismus surgery in adult patients.

The effects of vertical rectus muscle surgery on the anterior segment and iris fluorescein angiogram were documented in 43 eyes of 41 adult patients. Characteristic iris sector perfusion defects were seen in 33 of 37 eyes (89%) after primary vertical rectus muscle surgery (no previous surgery on these muscles). Although iris perfusion defects were commonly present, associated clinical signs were mild. Two patients developed permanent pupillary changes after simultaneous surgery on two rectus muscles (superior/inferior rectus muscles and contiguous inferior/medial rectus muscles). In most patients, clinical findings resolved and the iris circulation recovered during the first 2 weeks after surgery. In 3 of 8 patients with grade 3 anterior segment ischemia (pupil dysfunction and cells) or early "postoperative uveitis," recovery of iris circulation took up to 12 weeks. These findings indicate that the time course of recovery of the anterior segment circulation after vertical rectus muscle surgery may be shorter than previously assumed.

Adolescent↗
PubMed1990

Microvascular study of the retrolaminar optic nerve in man: the possible significance in anterior ischaemic optic neuropathy.

The morphology of the circle of Haller and Zinn and its variations were examined using methyl-methacrylate microvascular corrosion casting of human orbits obtained at post-mortem. It was found to be an elliptical microvascular anastomosis formed by branches of the medial and lateral para-optic short posterior ciliary arteries. The ellipse was divided into superior and inferior parts by the entry points of these branches into the eye, providing an altitudinal blood supply to the retrolaminar optic nerve. Morphological variations in terms of form, position and branches existed between subjects and between eyes from the same subject. The clinical implications of an elliptical 'circle' of Haller and Zinn providing an altitudinal blood supply to the retrolaminar optic nerve are relevant to the pathogenesis of altitudinal visual field defects in anterior ischaemic optic neuropathy.

Adult↗
PubMed1990

Functional anatomy of the choroidal circulation: methyl methacrylate casting of human choroid.

The functional anatomy of the normal choroidal circulation in man is described from scanning electron microscopic examination of methyl methacrylate microvascular casts. Distal and para-optic short posterior ciliary arteries supply wedge-shaped areas of choroid. Regional variations in choriocapillary morphology are well recognised; the lobules are densely packed at the posterior pole with a high capillary to inter-capillary ratio. Choroidal capillaries are flattened providing a large surface area for metabolic exchange with the retinal pigment epithelium. In acute choroidal ischaemia (from a variety of systemic disease), wedge shaped choroidal lesions may correspond to occlusion of short posterior ciliary arteries and geographic or focal lesions to occlusion of choroidal arterioles or choriocapillary lobules.

Capillaries↗
PubMed1989

Anterior segment vascular casting.

Vascular corrosion casting provides a permanent three-dimensional record of the deeper vasculature of the anterior segment whereas fluorescein angiography allows clinical examination of superficial vessels. Morphological findings on scanning electron microscopy of vascular casts of the anterior segment in sheep are presented and compared with that of man by casting techniques. Sheep illustrate the basic mammalian anterior segment vascular architecture but lack anterior ciliary arteries which connect with the deeper collateral arterial circles. The casting technique is described and its use to answer comparative anatomical, pathological and clinical questions explained. These techniques are being applied to examine changes to the anterior ciliary arteries and the deeper vessels following strabismus surgery in an animal model. Scanning electron microscopy of vascular corrosion casts has given a new dimension to micro-vascular anatomy.

Animals↗
PubMed1989

The effects of strabismus surgery on anterior segment circulation.

Anterior segment circulation was assessed in 35 adults one day after squint surgery by clinical observation and low-dose fluorescein iris angiography. Seventeen patients had primary vertical rectus muscle surgery and all showed angiographic evidence of ischaemia. No ischaemia was found in the 15 patients who had secondary vertical rectus muscle surgery, or any horizontal rectus muscle surgery. The staged group had intermediate findings between the above two. Age, dysthyroid eye disease and type of conjunctival incision did not correlate with fluorescein iris angiographic sector-filling delay on the first post-operative day. The time taken for the sector with delay to fill becomes less during the first two post-operative weeks. Redistribution of iris filling persists, however. This data suggest that the safe interval before further muscle surgery can be done is shorter than has previously been assumed. Since the anterior ciliary arteries do not reform into canals the probable mechanism of redistribution of blood flow is from the long posterior ciliary arteries and increased capacity of the collateral circulation.

Adolescent↗
PubMed1989

Children presenting to an ophthalmic casualty department.

A five month prospective survey of all children (0-14 years) attending an ophthalmic accident and emergency department was carried out to determine the disease profile and the primary ophthalmic health care provided. A data base was used to collect and analyse all cases. Seventy three per cent of 475 children attending had non-traumatic ophthalmic diagnoses, less than half being referred from their general practitioners. The remaining children had minor ophthalmic injuries of which less than one quarter were referred from their general practitioners. Four of the minor ophthalmic injuries were suspected of being non-accidental injury. The management of such cases is discussed. The ophthalmologist in an ophthalmic casualty department has an important role in the provision of primary ophthalmic care for children. In the management of minor ophthalmic injuries, the alerting factors for non-accidental injury should be sought, although the apparent incidence is low.

Adolescent↗
PubMed1989

Orbital and ocular micro-vascular corrosion casting in man.

The methods of preparation and examination of complete orbital and ocular vascular casts, suitable for the study of anterior segment vasculature, are described from our experience of 20 casts. The use of low viscosity methylmethacrylate produced complete vascular filling with few artefacts when injected into isolated orbital preparations from human cadavers 36-48 hours post-mortem, despite suggestions by previous authors that injection should be within 12 hours. Using scanning electron microscopy, arteries and veins are clearly distinguishable by their endothelial nuclear impressions. The vascular anatomy of the anterior segment and of other sites including the optic nerve and choroid in man can therefore be elucidated with this method.

Adult↗
PubMed1988

Forty years of retinoblastoma; into the fifth age.

Forty years of research into retinoblastoma has seen wide-ranging changes in our knowledge of the histogenesis of this childhood tumour and in the treatment of the disease. These changes, and some of the more recent developments in the molecular biology of this tumour are reviewed.

Child↗
PubMed1988

Simple retinoscopic screening.

A simplified retinoscopic technique to screen for refractive errors in children is presented. The technique described was assessed in 98 children and the results correlated with full retinoscopic refractions. All tests were done with cycloplegia. Orthoptists' results using the simple retinoscopy compared well with the full retinoscopic findings of the ophthalmologists, with an overall sensitivity of 90% and specificity of 74%. These results compare favourably with more technical refractive screening methods. This technique may be suitable as an adjunct to vision screening in pre-school children.

Child↗