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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↗
PubMed1981

Pigment release.

Guttae phenylephrine 10% produced a significant decrease in intraocular pressure and increase in facility of outflow in eyes with untreated ocular hypertension. If at the same time pigment was released into the aqueous, the pressure and outflow effect was nullified. Guttae pilocarpine 2% also reduced pressure and increased outflow, but if phenylephrine was added to the pilocarpine 2 responses appeared. If no pigment was released, pressure decreased and outflow increased; if pigment was released, there was no significant change in either. An identical response was shown by eyes with treated open-angle glaucoma. In eyes with treated exfoliation glaucoma pilocarpine and phenylephrine combined produced a significant increase in pressure and decrease in outflow because of pigment release. Finally, 18 eyes are described in which pigment release produced a mean increase in intraocular pressure of 14 mmHg. An acute release of pigment has an outflow-blocking effect that can be readily demonstrated. It provides an explanation for some of the paradoxical responses that occur after the instillation of autonomic drugs. It also provides a sufficient explanation for glaucoma associated with pigment dispersion.

Drug Combinations↗
PubMed1981

The fellow eye.

The result of a 10-year longitudinal study of the fellow eye at risk of developing closed-angle glaucoma (because the presenting eye had the disease) is described. 202 eyes were observed between 1 August 1970 and 31 July 1980. Each eye was provoked shortly after presentation using a pilocarpine phenylephrine provocative test. If the test produced a closed-angle glaucoma an iridectomy was done; if closed-angle glaucoma did not occur the eye was observed and it was reprovoked at yearly intervals. There were 3 possible outcomes for any one eye. Either the eye developed closed-angle glaucoma; or it was lost to follow-up; or at the end of the study the patient was alive, under observation, without having developed glaucoma. 90% of acute attacks occurred within 6 months of presentation. If an eye survived the first year without getting glaucoma the probability of its development in any one year period up to the fifth anniversary was 0.05; thereafter it was zero. The cumulative probability of an eye surviving to the fifth anniversary without glaucoma was 0.34, remaining constant thereafter; that is 34% of iridectomies are unnecessary. A high prevalence of ocular hypertension was seen in eyes that did not have an iridectomy (26%). It was concluded that a routine iridectomy is not necessary and that the fellow eye that will get glaucoma can usually be detected. The untreated fellow eye presents a naturally occurring model of one of the mechanisms involved in the production of ocular hypertension.

Aged↗
PubMed1981

Acute shallowing of the anterior chamber.

In aging eyes phenylephrine drops have no significant effect on the depth of the anterior chamber, whereas pilocarpine drops produce a significant shallowing. If both drugs are instilled simultaneously, a significantly greater decrease in anterior chamber depth occurs. The effect is seen in normal, glaucomatous, and hypertensive eyes, and in eyes with shallow anterior chambers. It did not occur in eyes that had had an iridectomy. During the course of a positive provocative test an acute reduction in anterior depth occurs which is reversed when the angle opens and pressure returns to normal levels. It is concluded that the depth of the anterior chamber is not a static dimension but that changes can occur which are rapid and transient. The mechanism of shallowing and deepening depends on an increase or a decrease in the pupil block force. It is a necessary consequence too that eyes with nonshallow anterior chambers can get closed-angle glaucoma and that this possibility cannot be detected by a conventional gonioscopic approach.

Acetazolamide↗
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↗