Exfoliation material on IOLs.
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Anterior Eye Segment↗
Biomedical subjects
G N Dutton
Publications and source records attributed to G N Dutton.
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↗
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↗
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↗
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↗
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↗
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↗
The characteristics of midfacial fractures and the association with ocular injury: a prospective study.
Ocular injuries commonly occur in patients with facial fractures. This prospective study was set up to determine the incidence of ocular injuries, as assessed by an ophthalmologist, in patients who had sustained midfacial fractures. Over a 2-year period, a study of 363 patients who had sustained midfacial trauma sufficient to lead to a facial bone fracture (438 fractures) was undertaken and patients received a comprehensive examination by an ophthalmologist and an orthoptist within 1 week of injury. The characteristics of the eye injuries sustained were related to the aetiology of the fracture, the type of fracture, and the sex and age of each patient. Ninety percent of patients sustained ocular injuries of various severities. Sixty three percent of patients sustained only minor or transient ocular injuries, 16% suffered moderately severe ocular injury and 12% experienced severe eye injuries. Road traffic accident was associated with the highest incidence of severe ocular disorder (9/45 = 20%) whilst assaults had the second highest incidence at 11% (20/181). One third of all patients with comminuted malar fracture suffered a severe ocular disorder (9/27) whilst blow-out fracture came second at 16.7% (6/36). Fifty six patients (15.4%) had a decrease in their visual acuity and 9 patients (2.5%) had significant traumatic optic neuropathy. Decrease in visual acuity was the main clinical finding accompanying the majority of significant eye injuries. When ocular injuries were related to aetiology, it was apparent that road traffic accidents and assaults associated with alcohol abuse showed the highest incidence of major ocular dysfunction. It is suggested that all patients sustaining midfacial fracture associated with a significant decrease in visual acuity either pre- or postoperatively should have an early ophthalmological review.
Accidental Falls↗
Diplopia following midfacial fractures.
Over a period of 2 years, 363 patients who had sustained a total of 438 midfacial fractures due to blunt trauma received a full ophthalmological examination within 1 week of injury. Of these, 72 patients (19.8%) developed diplopia. Diplopia was most common following road traffic accidents (31%) and least common with simple falls (10%). Blow-out fractures of the orbit led to double vision in 58% of cases. Eighty two percent of patients recovered from diplopia within 6 months of injury; only 1 patient required squint surgery for double vision. The principal risk factors for diplopia comprise road traffic accidents, blow-out fractures and comminuted malar fractures. Early surgical reconstruction of midfacial fractures with conservative management of concomitant motility disorders has, in our series, resulted in very few patients having diplopia in the long term.
Accidents, Occupational↗
Low vision aids--is our service cost effective?
A questionnaire and telephone survey was carried out on a Scottish population of patients with impaired vision, in order to ascertain the proportion of patients who gain benefit from Low Vision Aids (LVA) and to determine the number of LVAs which are retained but unused. One third of the patients who answered the questionnaire never use their LVAs, and one half were not satisfied with the service provided. A cost analysis indicated that approximately (pounds) 8,000 worth of LVAs are neither used nor returned each year to a single LVA service. The patients' ages, diagnoses, and visual acuities were related to the compliance rate. It appears that increasing age and decreasing visual acuity may be factors which decrease compliance. However none of the factors analysed could be used as a reliable predictor of patient satisfaction or of eventual benefit. Other health services which provide intensive training in the use of LVAs reportedly achieve a higher level of compliance. We conclude that our present service could probably be improved by the employment of additional staff specifically trained to teach patients how to make best use of the LVAs provided.
Adolescent↗
Etretinate and visual function: a 1-year follow-up study.
Concern has been expressed in the literature that the drug etretinate may be potentially retinotoxic. Four patients are reported who have received long-term treatment with etretinate and who have undergone detailed evaluation for the development of visual dysfunction over a 1-year period. Despite prolonged treatment and high total doses no evidence of ocular toxicity attributable to the drug was found in any of the patients.
Ectodermal Dysplasia↗
Gonioscopic findings in Greek patients with exfoliation glaucoma.
A prospective gonioscopic evaluation was carried out upon a cohort of Greek patients who had undergone trabeculectomy for open-angle glaucoma. Sixty-five patients were found to show clinical evidence of exfoliation glaucoma (EXG), whilst nine patients were deemed to have primary open angle glaucoma (POAG). The gonioscopic features of these eyes and of 43 non-operated eyes from the same patients with either exfoliation syndrome (EXS) or EXG are presented. The median degree of angle pigmentation was significantly higher in the operated eyes with EXG when compared with the POAG cases. In the operated eyes, deposition of exfoliation was found on the ciliary processes in 82% of cases and on the zonules in 52%.
Anterior Eye Segment↗
Optic foraminal radiography--a redundant investigation?
A retrospective study of all plain radiographs taken of optic foramina during the six years 1984-9 inclusive, comprising a total of 318 examinations, was carried out in order to determine the role of this investigation in patients with ophthalmic disorders. All but one of the radiographs were reported as showing no abnormality. However, for this exception, review of the radiographs showed that the optic foramina were asymmetrical but fell within the normal range. This study indicates that plain radiographs of the optic foramina have little or no useful function. Abandoning the use of these views as a routine will result both in a reduction in radiation hazard and in considerable financial saving.
Eye Diseases↗
Beam obstruction hazard on Q-switched Nd-YAG ophthalmic lasers: a safety device for the Nanolas laser.
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Eye Diseases↗
Reappraisal of the ratio of disc to macula/disc diameter in optic nerve hypoplasia.
The ratio of disc to macula/disc diameter is characteristically increased in eyes with optic nerve hypoplasia. We present the largest reported series of patients with a definitive diagnosis of optic nerve hypoplasia for whom this ratio has been determined. All measurements were made by an independent masked observer. Our results are in accordance with previous reports. A ratio of 2.94 provides a one-tailed upper population limit of 95%. An attempt has been made to correlate optic disc size and visual acuity. In 75% of bilateral cases the eye with the relatively smaller optic disc was found to have a better Snellen visual acuity than the fellow eye. This suggests that additional pathogenic mechanism(s) may have determined the eventual visual outcome in such eyes. Such mechanisms include macular hypoplasia, high refractive error, refractive amblyopia, central scotoma, and optic atrophy.
Adolescent↗
Optimum technique of light brightness assessment in control subjects and patients with ocular hypertension and glaucoma.
The light brightness test is an investigation in which crossed polarizing lenses placed in front of each eye are rotated with respect to one another to ellicit any disparity in perception of a diffusely illuminated screen. A number of different strategies can be employed to achieve the aim of determining the degree of disparity which is perceived as equal by the patient. A cohort of 45 control subjects was assessed in order to determine the ranges of brightness disparity accepted as equal for six methods of assessment. The method which gave the optimal confidence limit was to preset one pair of lenses at 0 degrees (maximum transmission) and the other as a fixed reference at 45 degrees. Rotation of the lens set at 0 degrees was carried out until the brightness of an X-ray box is perceived as equal. The strategy was then reversed. A disparity in one or both recordings greater than 76.5% is outside 99% confidence limits for the whole population studied. One of 14 patients with ocular hypertension gave a consistently 'positive' results. For the optimal method, over 60% of patients with glaucoma fell outside 95% condidence limits for normal controls indicating that a disparity in brightness perception between eyes is a common feature in glaucoma, in which the disease process usually affects one eye more than the other. For the patients with chronic glaucoma there was a positive correlation between the difference in brightness perception and the difference in central visual field score, indicating that brightness perception may be subserved by the central 30 degrees of the retina. When combined with visual acuity assessment this easily performed test warrants evaluation as a potential screening test for chronic glaucoma.
Chronic Disease↗
Quantitative mechanical assessment of the extraocular muscles.
The active and passive behaviour of the extraocular muscles can be investigated by measuring the force that must be applied to rotate the eyeball when the muscles are relaxed (the forced duction test) or the force required to maintain the eyeball stationary while the contralateral eye follows a moving target (the force generation test). Apparatus and test procedures for carrying out both tests are described. Normal values and confidence intervals for the tests have been obtained and the results of muscle entrapment and palsy illustrated.
Adolescent↗
Automatic chart reader--an example of computer systems for patients' data interpretation.
A new approach to the processing of circular medical charts based on "odd symmetry digital subtraction" is presented. The technique allows automatic digitisation of these charts using an image processing system based on a flat bed scanner. This approach is simple, fast, and reliable; and provides a system in which the digitised image is processed by a microcomputer to extract and quantify the plotted information. The main features and the potential applications of this approach in medical and nonmedical fields are discussed.
Algorithms↗