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Biomedical subjects

S T Ruben

Publications and source records attributed to S T Ruben.

7 recordsLinked to original sources
PubMed1998

Vertical cup/disc ratio in relation to optic disc size: its value in the assessment of the glaucoma suspect.

AIMS: The vertical cup/disc ratio (CDR) has long been used in the assessment of the glaucoma suspect, though the wide range of CDR values in the normal population limits its use. Cup size is related physiologically to disc size and pathologically to glaucomatous damage. Disc size can be measured at the slit lamp as the vertical disc diameter (DD). The ability of the CDR, in relation to DD, to identify glaucomatous optic discs was investigated. METHODS: 88 normal, 53 early glaucoma, and 59 ocular hypertensive subjects underwent stereoscopic optic disc photography and clinical biometry. Photographs were analysed in a masked fashion by computer assisted planimetry. The relation between vertical cup diameter and DD was explored by linear regression, and expressed in terms of CDR. The upper limit of normal was defined by the 95% prediction intervals of this regression (method 1) and by the upper 97.5 percentile for CDR (method 2). The sensitivity and specificity of CDR to identify an optic disc as glaucomatous was tested with these disc size dependent and disc size independent cut offs in small, medium, and large discs. RESULTS: The CDR was related to DD by the equation CDR = (-1.31 + (1.194 x DD))/DD. The sensitivity in small, medium, and large discs was 80%, 60%, and 38% respectively for method 1 and 33%, 67%, and 63% respectively for method 2. Specificity was 98.9% (method 1) and 97.7% (method 2). CONCLUSIONS: The CDR, relative to disc size, is useful clinically, especially to assist in identifying small glaucomatous discs.

Diagnosis, Computer-Assisted↗
PubMed1995

Pattern electroretinogram and peripheral colour contrast thresholds in ocular hypertension and glaucoma: comparison and correlation of results.

AIMS: Both pattern electroretinogram and peripheral colour contrast thresholds have been shown to be abnormal in glaucoma and ocular hypertension. This study evaluates each of these tests as tools for the early diagnosis of glaucoma, compares and contrasts the results, and examines the relation between the two tests in a large cohort of ocular hypertensive patients. METHODS: Transient and steady state pattern electroretinograms and peripheral colour contrast thresholds were performed in 45 normal, 37 glaucomatous, and 206 ocular hypertensive eyes. The results were analysed using receiver operating characteristic curves, together with evaluation of sensitivity and specificity of the tests. The relation between the two tests was examined by direct statistical correlation of the results. RESULTS: All tests showed high sensitivity and specificity for discriminating between normal and glaucomatous eyes. However, there was a significant difference between the two tests for the number of ocular hypertensives considered as abnormal. Forty per cent of ocular hypertensives had abnormal pattern electroretinogram compared with 30% with abnormal peripheral colour vision. Peripheral colour contrast thresholds showed a significant correlation with both transient and steady state pattern electroretinogram. CONCLUSION: Both of these tests have been shown to be promising new tools for the early detection of glaucoma but the number of ocular hypertensive patients showing abnormal results is rather higher than expected considering the natural history of the condition. Sensitivity in ocular hypertension may be increased by using a combination of both tests. The significant correlation between these psychophysical and electrophysiological tests is discussed.

Aged↗
PubMed1994

The use of botulinum toxin for treatment of acquired nystagmus and oscillopsia.

PURPOSE: To evaluate the role of botulinum toxin A (BTA) in treating patients with diminished visual acuity secondary to acquired nystagmus and oscillopsia. METHODS: Twelve patients with acquired nystagmus causing oscillopsia and reduced vision were treated with injection of BTA. Botulinum toxin A was injected directly into the horizontal recti in three patients, and in nine patients retrobulbar BTA was administered. Injections were given at 3- to 4-month intervals and repeated as long as patients noted improvement in their quality of life. RESULTS: Improvement in visual function varied, and not all patients benefited from the procedure. However, 8 of 12 patients demonstrated a measurable improvement in visual acuity. Transient ptosis was the most common side effect. CONCLUSION: Retrobulbar BTA provides a simple and safe alternative in managing a condition for which alternative treatments are typically unsatisfactory.

Adult↗
PubMed1994

Electrophysiology and psychophysics in ocular hypertension and glaucoma: evidence for different pathomechanisms in early glaucoma.

It is not clear whether glaucomatous optic nerve damage is the end result of one pathological process or whether there are several mechanisms by which the final disease is manifest. The use of electrophysiological and psychophysical tests which measure the function of specific subdivisions of the visual pathways have been shown to be of use in the early diagnosis of glaucoma. In addition these results may help to elucidate the mechanisms of loss of visual function in patients with early glaucoma. One hundred and ninety-three patients with ocular hypertension (intraocular pressure > 24 mmHg, with normal visual fields and optic discs), 30 with glaucoma and 35 controls underwent pattern electroretinogram (PERG), peripheral colour contrast thresholds, motion detection thresholds (MDT) and Humphrey automated visual fields at the same visit. For each test there was a significant proportion of patients with abnormal results as has been found in previous studies of these techniques. However, there was a significant lack of correlation between the groups with only a small number of patients having abnormalities on more than one test. Of the patients demonstrating abnormal PERGs, 36% had abnormal colour contrast and 32% abnormal MDT, but only 15% were abnormal on both tests. Early glaucomatous damage may be focal or diffuse in nature. Similarly there may be preferential damage to ganglion cells subserving different visual functions or damage at different retinal layers. The results lend support to these hypotheses and give further evidence that more than one pathomechanism may be involved early in the glaucomatous process.

Color Perception↗
PubMed1994

Corneal sensation in insulin dependent and non-insulin dependent diabetics with proliferative retinopathy.

The corneal sensation of diabetic patients undergoing pan retinal photocoagulation for the treatment of proliferative retinopathy was measured using the Cochet-Bonnet aesthesiometer. Insulin dependent and non-insulin dependent diabetics both showed significantly decreased corneal sensitivity, and there was no significant change following pan-retinal photocoagulation. Insulin dependent diabetics with proliferative retinopathy had been diagnosed for a significantly longer period than non-insulin dependent diabetics, but had better corneal sensitivity than the latter group. Male patients were more likely to have brown irides, whereas there was a preponderance of blue irides amongst the females. Patients with blue irides also had significantly lower sensitivity than patients with brown irides. The results are discussed.

Adult↗
PubMed1992

One stage adjustable sutures: practical aspects.

Strabismus surgery using one stage adjustable sutures was carried out under local anaesthesia in six patients with good results. The criteria for patient selection and the surgical technique are discussed.

Adult↗