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Biomedical subjects

G N Dutton

Publications and source records attributed to G N Dutton.

At least 73 records · Page 4Linked to original sources
PubMed1994

Simultaneous interocular brightness sense testing in ocular hypertension and glaucoma.

OBJECTIVE: To investigate the performance of the simultaneous interocular brightness sense test in patients with ocular hypertension and primary open angle glaucoma (POAG). DESIGN: Brightness matches were obtained for an age-matched control sample and for patients with ocular hypertension and POAG. In addition, for the patients with POAG, visual field defects were quantified and a risk factor count was established for those with ocular hypertension. PATIENTS: Nineteen patients with ocular hypertension, 20 patients with POAG, and 61 age-matched controls participated in the study. RESULTS: Seven patients with ocular hypertension exhibited brightness perception asymmetry outside normal limits for age-matched controls. Of these, six were at high risk of having glaucoma develop and only one of the remaining 12 was found to be at similar risk. All 20 patients with established POAG had results outside the normal limits for a test sensitivity of 100%. Three control observers had abnormal results, giving a test specificity of 95%. CONCLUSION: The simultaneous interocular brightness sense test is quick and simple to perform and is suitable for a wide age range of patients. It warrants further assessment as a means of screening for ocular hypertension and glaucoma.

Adult↗
PubMed1994

Retrobulbar haemorrhage: can blindness be prevented?

Retrobulbar haemorrhage is a rare complication following orbital trauma or surgery occurring in less than 1 per cent of cases. Early diagnosis and treatment of this complication may save the vision of the affected eye. This paper illustrates cases where diagnosis was not made and blindness resulted. We also present two cases of successful treatment due to early diagnosis.

Adult↗
PubMed1994

Impaired perception of moving objects after minor injuries to the eye and midface: the Pulfrich phenomenon.

Delayed conduction along one optic nerve can result in an incorrect appreciation of moving objects. The temporal mismatch between the two different pathways results in altered perception of the vector of a moving target and is known as 'the Pulfrich phenomenon'. This is a well-recognised handicap in patients with multiple sclerosis, but has not previously been reported as a consequence of injury. All 187 patients who presented during 1991 with reduced visual acuity as a result of midfacial injuries were examined with a pendulum. Six had the defect and five of these had symptoms. In each case the patients were disturbed by car travel, because they perceived oncoming traffic moving in a hyperbolic curve towards them. These patients have been examined in detail and given a tinted lens for the normal eye to eliminate the illusion by delaying the input from the normal side to equal that on the damaged side. We recommend that this phenomenon is sought in all patients with mid-facial injuries or with later evidence of mild traumatic optic neuropathy, particularly if they are disturbed by car travel.

Automobiles↗
PubMed1994

Subclinical operating microscope retinopathy: the use of static perimetry in its detection.

Focal retinal pathology and dysfunction as a sequel to manifest damage due to operating microscope illumination is well recognised. We wished to determine whether retinal dysfunction could be identified in the absence of clinically visible lesions. We therefore have conducted a prospective controlled study on 36 patients undergoing cataract surgery and 27 control subjects. A Wild M690 zoom operating microscope was used for each procedure. No filters were used. The Humphrey visual field equipment was employed to determine threshold retinal sensitivity at predetermined loci above and below fixation in both groups. No clinically visible retinal lesions were seen in any patient. However, post-operative investigation revealed a statistically significant depression in retinal sensitivity at points most exposed to operating microscope illumination (p < 0.05). This was most noticeable following longer total operating times and in patients with the longest time intervals between lens extraction and completion of the procedure. It is concluded that operating microscope position and centration, and the position of the eye, should be adjusted to place the image of the illuminating element away from the foveola. Also retinal illumination should be kept to a minimum, particularly after an intraocular lens has been implanted.

Aged↗
PubMed1994

Argon laser photocoagulation of fluorescein stained retina--an unrecognised hazard?

Sodium fluorescein staining of the retina following fluorescein angiography may affect the absorption characteristics of argon ion laser photocoagulation. This hypothesis was investigated by performing laser photocoagulation on control and fluorescein stained porcine retinas. The resultant damage was viewed by scanning electron microscopy. In both specimens, argon irradiation produced damage to the pigment epithelium and overlying photoreceptor layer. The control sample showed a deep cylindrical burn, indicative of internal heating, in both retina and choroid. The fluorescein stained sample showed damage consistent with thermal interaction from the surface downwards leaving the choroid relatively spared. This preliminary study demonstrates that fluorescein staining of the retina changes the absorption site of argon laser light and this subject clearly merits further investigation.

Animals↗
PubMed1994

Ophthalmic features of fourteen cases of Goodpasture's syndrome.

Juxtapapillary subretinal neovascular membranes developed in both eyes of a patient who had been treated for Goodpasture's syndrome for 4 years. These lesions caused visual impairment but were successfully treated by laser photocoagulation. Subretinal neovascularisation has not been reported before in association with Goodpasture's syndrome, but diverse ocular abnormalities have been described. It is not certain whether these lesions were caused by anti-basement-membrane auto-antibodies. The eyes of 13 other patients with Goodpasture's syndrome were examined, in order to detect other unsuspected ocular pathology. In 1 further patient, both retinae contained a few unexplained superficial retinal haemorrhages. During follow-up, the original patient developed bilateral peripheral retinoschisis. From this short series and from cases previously described, we conclude that sight-threatening ocular abnormalities are rare in Goodpasture's syndrome. It is, however, particularly important to be aware of the possibility of treatable eye disease in Goodpasture's syndrome, since the introduction of effective treatment with immunosuppression and plasmapheresis has made long-term survival likely.

Adolescent↗
PubMed1993

Color Doppler velocimetry of the optic nerve head in arterial occlusion.

BACKGROUND: Color Doppler velocimetry allows simultaneous imaging by B-scan and Doppler ultrasound. This facilitates estimation of blood velocity in the orbital vessels. A pulse arterial waveform providing blood velocity measurements can be obtained from the optic nerve head. The vascular pattern in this region consists of multiple peripapillary blood vessels and a central artery. The exact contribution of the arteries in this area to velocimetry readings was undetermined. METHODS: In this study, the arterial pulses at the optic nerve head of seven patients with central retinal artery occlusion (CRAO) and seven with anterior ischemic optic neuropathy (AION) were examined by color Doppler velocimetry. RESULTS: No velocimetric measurements were obtainable at the optic nerve head in three of four patients with acute CRAO (examined within 24 hours of onset) despite color recordings obtainable in the peripapillary region. In contrast, all patients with AION showed characteristic arterial pulse waveforms from the artery that was situated centrally in the optic nerve. No peripapillary color indices were detectable in three of the four patients with ischemic optic neuropathy who were examined within 24 hours of onset of their symptoms. Follow-up investigation showed that there was reperfusion of both arterial circulations within 1 week. CONCLUSION: The results demonstrate that color Doppler ultrasound of the optic nerve head provides velocimetric measurements of blood flow in the central retinal artery. Although some investigators using different apparatuses have produced velocimetry measurements from the posterior ciliary arteries, in this study reliable measurements were not obtainable form color indices in the peripapillary area.

Aged↗
PubMed1993

Colour Doppler velocimetry of the arterial vasculature of the optic nerve head and orbit.

Blood flow in the orbital vasculature can be investigated by colour Doppler velocimetry which allows simultaneous imaging of B-scan and Doppler ultrasound. In this paper we review the results of our recent studies on the arterial vasculature of the orbit and optic nerve head. A control study is described in which reliable measurements were obtained from the ophthalmic artery at the orbital apex, the medial orbit, and the complex of the central retinal artery and posterior ciliary arteries. Patients with occlusion of the central retinal artery and posterior ciliary arteries were examined. The results indicate that readings at the optic nerve head primarily represent blood flow in the central retinal artery. A study of the effects of posture on velocimetry demonstrated no change in the measurements obtained. Finally, topical timolol 0.5% was found to reduce the resistive indices of flow in the central retinal artery.

Adult↗
PubMed1992

Ophthalmic consequences of mid-facial trauma.

Fractures of the mid-face are commonly accompanied by injury to the visual system. Three hundred and sixty three patients who had sustained mid-facial fractures were assessed prospectively for evidence of such injury. The data have been used to devise a scoring system for the maxillofacial surgeon in order to help identify those patients at risk of eye injury. The scoring system has been evaluated on a further cohort of 100 patients with a similar spectrum of injury and the sensitivity and specificity of the system have been determined. The results of these studies have been reported in the maxillofacial literature. This paper reviews the data and results obtained. In summary, impaired visual acuity with a comminuted or out blow fracture, a motility abnormality, or facial fracture combined with head injury, sufficient to cause both retrograde and post-traumatic amnesia, emerged as major risk factors which are indicative of an adverse ophthalmic outcome deemed to warrant referral. The scoring system which was developed from this data was found to have a sensitivity of 94.4% and a specificity of 89% for the detection of patients thought to merit ophthalmic assessment. Failure to assess central visual function as objectively as practicable in patients who have sustained mid-facial fractures may lead to potentially treatable ophthalmic pathology not being identified.

Diplopia↗
PubMed1992

Colour Doppler ultrasound in the management of a case of cranial arteritis.

Colour Doppler ultrasound allows simultaneous B scan and Doppler imaging and can be employed to determine the velocity of blood flow in the vasculature of the eye and orbit. We describe a case of cranial arteritis (giant cell arteritis) in which serial velocimetry recordings were obtained. At one stage in the disease process no blood flow was detectable in the orbit despite previously reliable recordings. This coincided with a deterioration of the clinical state of the patient as signified by recurrent anterior ischaemic optic neuropathy despite controlled symptomatology and erythrocyte sedimentation rate by prednisolone therapy. Subsequent increase in the immunosuppressive therapy was accompanied by a return of blood flow in the orbit. Colour Doppler ultrasound may prove to be a useful examination technique in the diagnosis and management of cranial arteritis.

Aged↗
PubMed1992

Color Doppler ultrasound of orbital and optic nerve blood flow: effects of posture and timolol 0.5%.

Color Doppler ultrasound allows simultaneous imaging with real-time ultrasound and superimposed color-coded vascular flow, allowing visualization of vessels previously beyond the resolution of conventional imaging, such as those in the orbit. With this technique, 20 healthy volunteers were studied. Three regional vessels named 1, 2, and 3 were identified. No significant difference in maximum or minimum blood velocity or resistive index was detected between vessels 1 and 2, although significant differences were noted between both these vessels and vessel 3 (P less than 0.01 and P less than 0.001, respectively). These regional variations are unaffected by small but significant rises in pulse (P less than 0.05) and diastolic blood pressure (P less than 0.01) induced by postural change. No significant change within each vessel was recorded in response to posture, reflecting autoregulation within these vessels. Using a similar technique, 10 healthy volunteers were studied at baseline and at 2 hr and 3 d following the unilateral instillation of 0.5% timolol eye drops. A fall in resistive index was recorded in vessel 3 for both eyes (P less than 0.05, timolol administered eye; P less than 0.01 timolol-free eye). This effect was independent of any simultaneous fall in intraocular pressure that occurred only in the eye receiving timolol drops (P less than 0.01). These results support the presence of B receptors in the vessels at the optic nerve head (vessel 3). A fall in resistive index should not compromise the blood supply in this region, and may even increase it.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1992

Patterns of tissue damage produced by repeated use of a corneal trephine: a scanning electron microscopic study.

We studied by scanning electron microscopy the effects of the repeated use of a newly-designed, disposable, suction trephine (Microsurgical, Ltd, Bedfordshire, England) on the nature of the cut of successive corneal buttons from sheep eyes. After the trephine was used more than nine times, the cut edge became more irregular as successive buttons were produced. Also, progressively greater degrees of endothelial cells adjacent to the cut edge were lost. Although the corneal buttons initially were circular, those produced after the 20th cut became more oval. These results suggest that a disposable corneal trephine should be reused no more than nine times.

Animals↗
PubMed1991

Midfacial fractures and the eye: the development of a system for detecting patients at risk of eye injury.

Maxillofacial trauma is often complicated by injury to the eye. Such injuries may be difficult to detect and may therefore be missed. Detailed ophthalmic examinations were carried out prospectively on 363 patients who had sustained midfacial fractures. Fifty four parameters comprising maxillofacial, radiological and ophthalmic data were recorded and coded for each patient. All encoded data were divided into predictors (the data potentially available to the maxillofacial surgeon) and outcome (the data potentially available to the ophthalmologist). Statistical methods of regression, and the analysis of contingency tables, led to the identification of the principal predictors indicative of underlying ophthalmic injury and thence to a scoring system which predicts the severity of such injuries. Impaired visual acuity is the principal predictor and when employed alone gives a sensitivity value of 80%. Pure blow-out fracture or comminuted facial fracture, double vision and amnesia emerged as additional factors which yielded an efficient scoring system with a sensitivity of 89% and specificity of 90% for the population upon which it was based. A score sheet is provided in the paper. These predictors can be remembered from the acronym Blow-out fracture, Acuity, Diplopia, Amnesia, Comminuted Trauma. As many such injuries result from a BAD ACT, it is easily remembered. This scoring system requires to be tested upon a new population of individuals in order to determine its efficacy.

Amnesia↗
PubMed1991

Midfacial fractures and the eye: the development of a system for detecting patients at risk of eye injury--a prospective evaluation.

Midfacial trauma is often complicated by ocular disorder. A scoring system has been devised to help the maxillofacial surgeon identify patients who warrant referral to an ophthalmologist. A prospective pilot study was carried out on 100 patients with midfacial fractures to evaluate the effectiveness of this system in clinical practice. The sensitivity value was 94.4% and the specificity value was 89%. Only 1 patient, who clinically warranted referral to an ophthalmologist, was missed by the system whilst 9 others were incorrectly classified as warranting referral. The results of this evaluation demonstrate the competence of the system.

Cohort Studies↗