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Biomedical subjects

R Mapstone

Publications and source records attributed to R Mapstone.

At least 19 recordsLinked to original sources
PubMed1987

Parasympathetic denervation hypersensitivity of the iris in ocular hypertension.

Seventy-eight ocular hypertensive patients and 47 age-and sex-matched control subjects were assessed for parasympathetic denervation hypersensitivity of the iris using topical application of 2.5% methacholine chloride solution. Constriction of the pupil in response to methacholine stimulation of the sphincter pupillae was significantly greater in the ocular hypertensive patients than the control group (P less than 0.001). The implications are discussed, with particular reference to the association between autonomic neuropathy and the primary glaucomas.

Administration, Topical↗
PubMed1986

The prevalence of diabetes mellitus in the family history of patients with primary glaucoma.

The prevalence of diabetes mellitus in the family history of 371 patients with primary glaucoma--closed-angle glaucoma, ocular hypertension and open-angle glaucoma--and 85 age- and sex-matched control subjects was determined. There was a significantly-increased prevalence of familial type 2 diabetes mellitus (non-insulin dependent diabetes mellitus) in patients with closed-angle glaucoma (p = 0.004) and ocular hypertension (p = 0.02). Primary glaucoma was not associated with familial type 1 diabetes mellitus (insulin dependent diabetes mellitus). The implications are discussed.

Aged↗
PubMed1986

Systemic autonomic neuropathy in open-angle glaucoma.

Systemic autonomic nerve function was assessed in 67 patients with open-angle glaucoma and 76 age- and sex-matched control subjects, using a series of well-established tests based upon cardiovascular reflex responses to standardised stimuli. Parasympathetic neuropathy was present in 37.3% of open-angle glaucoma patients compared with 2.6% of the control group. Demonstration of a significant association between autonomic neuropathy and primary glaucoma may provide a logical rationale for the efficacy of autonomic medication in glaucoma therapeutics; the prognostic implications are discussed.

Aged↗
PubMed1986

Anterior segment autonomic dysfunction in ocular hypertension.

Autonomic nerve function in the anterior segment of the eye was assessed by measurement of the pupil cycle time in 189 patients with ocular hypertension and 70 age- and sex-matched control subjects. Parasympathetic dysfunction was significantly present in ocular hypertensive patients with narrow irido-corneal angles, though not in wide-angle subjects. The results are discussed, with particular reference to the accumulating evidence implicating autonomic dysfunction as a significant factor in the pathogenesis of the primary glaucomas.

Adult↗
PubMed1986

Age-adjusted normal tolerance limits for cardiovascular autonomic function assessment in the elderly.

Autonomic nerve function was assessed in 85 normal subjects (mean age 66.1 +/- 10.2 years) by a series of standard tests based upon cardiovascular reflexes. Age-adjusted normal tolerance intervals were established for each test. The clinical application of autonomic function assessment in the elderly is discussed, with particular reference to patients with diabetes mellitus, ocular hypertension, and primary glaucoma, which represent a significant proportion of the aged population.

Adult↗
PubMed1986

Progression of impaired glucose tolerance to diabetes mellitus in patients with primary glaucoma and ocular hypertension.

In 375 patients aged 68.5 +/- 9.4 years (mean +/- 1 SD) with primary glaucoma subdivided by irido-corneal angle configuration into closed-angle glaucoma (123 cases), ocular hypertension (186 cases), and open-angle glaucoma (66 cases), diabetic status was determined by standard 75 g oral glucose tolerance tests. In 63 patients with impaired glucose tolerance who were retested one year later, 16% had progressed to diabetes mellitus. The results confirm a significant association between non-insulin dependent diabetes mellitus and primary glaucoma which may result from autonomic dysfunction in parasympathetic tone causing anterior chamber angle closure.

Aged↗
PubMed1986

Pupil cycle time in primary closed-angle glaucoma.

Pupil cycle time was measured in fellow eyes of 118 patients with closed-angle glaucoma and 70 age- and sex-matched control subjects. Results indicate that the duration of pupil cycle time was significantly prolonged in patients with closed-angle glaucoma as compared to the control group (p less than 0.001); in addition, the prevalence of absent pupillary oscillation was significantly increased in closed-angle glaucoma patients (p less than 0.001). The implications are discussed, with particular reference to the association between closed-angle glaucoma and systemic parasympathetic neuropathy.

Aged↗
PubMed1985

Autonomic neuropathy in ocular hypertension.

By means of a series of cardiovascular autonomic function tests, systemic parasympathetic neuropathy was demonstrated in 41.8% of 189 patients with ocular hypertension and in 2.6% of 76 controls. Parasympathetic neuropathy was significantly more common in patients with narrow-angle hypertension than in those with wide-angle hypertension. Raised intraocular pressure may be a manifestation of systemic disease rather than an exclusively ocular phenomenon.

Aged↗
PubMed1985

Prevalence of diabetes in glaucoma.

Oral glucose 75 g was given to 352 patients with chronic glaucoma, acute glaucoma, or ocular hypertension and 73 patients without glaucoma. The proportion of patients with shallow anterior chambers who showed an abnormal response was significantly greater than that in patients with deep anterior chambers and in the control group (p less than 0.005). The probability of developing an abnormal response to oral glucose tests increased as the depth of the anterior chamber decreased; these two variables showed a significant negative linear correlation (r = -0.79, p less than 0.001). The high prevalence of autonomic dysfunction in patients with shallow anterior chambers and glaucoma may explain this association. Because of this, acute glaucoma should be regarded as a symptom of diabetes.

Aged↗
PubMed1985

Diurnal variation in the dimensions of the anterior chamber.

Anterior chamber depth and volume were measured photogrammetrically on a diurnal basis in 38 eyes from 21 normal subjects. Significant diurnal variation in anterior chamber dimensions was demonstrated. Anterior chamber depth and volume measurements were significantly lower in the evening than in the morning, with particular emphasis on the periphery of the anterior chamber. Axial depth decreased by 2.1%; peripheral depth, by 21.1%; and anterior chamber volume, by 5.7%.

Aged↗
PubMed1979

One gonioscopic fallacy.

Traditional gonioscopic practice assumes that, if most of the angle is gonioscopically closed, intraocular pressure increases. Evidence is produced to show that this is fallacious, because at its inception angle closure is iridocorneal contact occurring on the corneal side of the limbus. Although the angle cannot be seen by means of a gonioscope, there is initially no iridotrabecular contact. It is only after pressure increases that iris is pushed against trabecular meshwork and the angle is truly closed.

Aged↗
PubMed1979

One model of outflow damage.

The intraocular pressure, facilities of outflow, and Po/C ratios of 3 groups of eyes were compared. Group 1 consisted of 20 eyes at risk to the development of acute closed-angle glaucoma that had been treated with prophylactic pilocarpine for at least 8 years. Group 2 consisted of 20 eyes at risk that had received no treatment and had been followed up for at least 4 years. Group 3 comprised 20 eyes in which there was no evidence of glaucoma. There were highly significant differences between the 3 groups. The 60 eyes were then provoked with pilocarpine and phenylephrine; 90% of Group 1, 75% of Group 2, and none of Group 3 developed significant gonioscopic angle closure. These results suggest that asymptomatic partial angle closure was the cause of the observed changes and provide a naturally occurring model of one mechanism that can produce outflow damage without clinical symptoms.

Anterior Chamber↗
PubMed1979

Mechanisms in ocular hypertension.

This paper investigates the hypothesis that intermittent partial angle closure is one of the causes of ocular hypertension. 139 eyes from 76 patients with ocular hypertension were provoked with pilocarpine and phenylephrine. Four distinct responses appeared. Firstly, in 39 eyes (from 24 patients, 32%) gonioscopic closure of part or all of the angle appeared. Secondly, in 30 eyes (from 19 patients, 25%) no angle closure occurred but there was a substantial pigment release into the aqueous. Thirdly, in 9 eyes (from 8 patients, 11%) both angle closure and pigment release occurred. Finally, in 61 eyes (from 36 patients, 59%) neither angle closure nor pigment release appeared. (Since the 2 eyes of a patient did not always behave in the same way, for example, 1 eye might develop angle closure and the other not, 1 patient may appear in 2 groups.) From the first group 1 eye from each patient was randomly chosen for iridectomy. A repeat provocative test at least 1 year later produced a significantly different result. It is considered that the evidence obtained in this study supports the hypothesis that intermittent partial angle closure is one of the causes of ocular hypertension.

Anterior Chamber↗
PubMed1978

Mechanisms in open-angle glaucoma.

One hundred and nineteen eyes from 68 patients with open-angle glaucoma were provoked by means of a pilocarpine phenylephrine provocative test. In 22% the response was the same as that seen in normal eyes. In 78% the response was the same as that seen in contralateral eyes at risk to the development of closed-angle glaucoma, which do not develop a positive provocative test. The 68 patients were randomised and 34 submitted to a "dummy" provocative test. No significant change in pressure or outflow occurred. Fifty-two of the 93 eyes with an abnormal provocative test were selected for a peripheral iridectomy and reprovoked at least 6 months after operation. The results were significantly different from those obtained before operation. It was concluded that partial-angle closure could be demonstrated in some eyes with apparent open-angle glaucoma. The mechanisms involved in the production of partial-angle closure in eyes with apparent open-angle glaucoma are discussed.

Dose-Response Relationship, Drug↗
PubMed1977

Outflow changes in positive provocative tests.

The outflow changes in 26 eyes were measured during the course of a positive provocative test with pilocarpine and phenylephrine. Three separate patterns of response occurred: (1) One dose of pilocarpine and phenylephrine produced an acute attack with a large reduction in outflow. (2) The first dose of pilocarpine and phenylephrine produced a fall in pressure and increase in outflow. The second dose reversed this effect and closed the angle. (3) The first dose of pilocarpine and phenylephrine increased pressure by an insignificant amount and decreased outflow. The second dose accentuated this response and produced an acute attack.

Aqueous Humor↗