Search PubMed⌕ Search

Biomedical subjects

C I Phillips

Publications and source records attributed to C I Phillips.

At least 37 records · Page 2Linked to original sources
PubMed1990

Corneal arcus: some morphology and applied pathophysiology.

The frequency and density of corneal arcus in 101 patients (101 eyes), 54 males and 47 females, were greatest in the 12 o'clock sector of the peripheral cornea. Sectors below 12, nasally and temporally, were approximately symmetrically affected. Both properties decreased progressively and significantly at the 11 and 1 o'clock sectors, then 10/2, then 9/3; 8/4 and 7/5 differed insignificantly from each other but were significantly less affected than 9/3, and more affected than 6 o'clock. Breadth and density were significantly positively correlated. The greater vascularity and higher temperature at the upper limbus might explain this pattern. The morphology of arcus is concluded to indicate the site of a peripheral corneal filter which prevents ingress of large light-scattering particles with the centripetal flow of tissue fluid. Filtration of immune complexes at the same site may initiate tissue destruction, hence some peripheral corneal ulcerations.

Adult↗
PubMed1989

Topical dexamethasone lowers rabbit ocular tension, as does topical mifepristone (RU 486), a peripheral blocker of dexamethasone and progesterone.

The variability of the response of the rabbit eye to topical 1% dexamethasone has been shown in two groups of 20 young albino rabbits each (total 40) tested in succession. The pressure anomalously fell significantly (but by only 1 mm Hg) in both groups in the first 4 weeks of administration, but not in subsequent weeks. Mifepristone (RU 486), a peripheral antagonist of dexamethasone and progesterone, reduced the pressure significantly, again by only 1 mm Hg, in the first group of 20 rabbits, not the second. Accordingly, no conclusion was possible on the originating question: does pre-treatment with mifepristone prevent the dexamethasone-induced rise in rabbit intra-ocular pressure?

Administration, Topical↗
PubMed1989

Interaction between progesterone and mifepristone on intraocular pressure in rabbits.

The interaction between a topically administered progesterone, medrysone, and a steroid antagonist, mifepristone, on rabbit intraocular pressure (IOP) has been determined. Medrysone alone increased IOP significantly above parallel controls over the first three weeks; this increase was not sustained. When medrysone and mifepristone were given simultaneously the IOP increased initially, but then fell after two weeks to control levels. When mifepristone was added 14 days after medrysone, the IOP was again reduced to, or below, control levels by mifepristone. The use of mifepristone alone reduced IOP relative to controls and the further addition of medrysone at 14 days had no effect on IOP. It appears that mifepristone is an effective antagonist against progesterone effects on IOP.

Animals↗
PubMed1988

Aqueous humor flow rate and intraocular pressure during and after pregnancy.

Intraocular pressure and aqueous humor formation rate have been determined from the first trimester of pregnancy through term, with further determinations 3 months postpartum, in 7 patients. The intraocular pressure showed a consistent, statistically significant fall during pregnancy, returning to values seen in early pregnancy after delivery. Aqueous humor formation rate showed no change during pregnancy. The data indicate that the sustained elevated hormonal levels during pregnancy, either directly or indirectly, cause an increase in fluid outflow conductance from the eye without altering the rate of fluid entry.

Adult↗
PubMed1988

Aniridia, ectopia lentis, abnormal upper incisors and mental retardation--an autosomal recessive syndrome.

A 13-year-old boy presented with bilateral aniridia, ectopia lentis, two palatally placed upper incisors which may be supernumerary teeth or may be malpositioned lateral incisors, and mental retardation. The cause is very probably a single autosomal recessive gene defect although the mental state may have a separate, genetic cause. Since his parents, who are normal, are second cousins and his father's and his mother's parents are also full cousins, the coefficient of inbreeding is 1/64 which is only 25% of the coefficient for full cousinhood of parents alone (1/16). No biochemical correlate has been identified.

Adolescent↗
PubMed1987

Centripetal movement of fluorescein dextrans in the cornea: relevance to arcus.

The centripetal movement of fluorescein and fluorescein-labelled dextrans (4 to 150 kD) from sclera or cut edge of the cornea was determined in isolated rabbit corneas at 4 and 24 h. Corneas were divided into 5.5 mm diameter central core, inner 5.5 to 8 mm donut, 8 to 12 mm peripheral donut and, where applicable, scleral rim. For all molecules greater than sodium fluorescein (376 D) tracer concentrations in the 5.5 mm core and the 5.5 to 8 mm donut were equal. Without sclera rim, the more central portions of the cornea (5.5 mm core and 5.5 to 8 mm donut) had tracer concentrations equal to those of corneas-with-sclera for all tracers greater than 10 kD. The tracer concentrations in the central cornea were the same in the presence or absence of sclera. The data indicate a physiological barrier to the lateral diffusion of molecules greater than 10 kD between the peripheral and more central cornea.

Animals↗
PubMed1987

Posterior synechiae after glaucoma operations: aggravation by shallow anterior chamber and pilocarpine.

Posterior pupillary synechiae affect a proportion of eyes subjected to iridectomy with or without drainage operation because (1) aqueous humour bypasses the pupil; (2) traumatic iridocyclitis occurs; (3) there is immobility of the iris in the iridectomy sector; (4) in eyes with angle closure glaucoma closer apposition of the iris to the anterior lens capsule increases the tendency; (5) pilocarpine aggravates (4) both in angle closure glaucoma and open angle glaucoma and produces a small immobile pupil facilitating pupillary membrane formation (occlusio pupillae). Pilocarpine should be avoided if possible as medical treatment at any time after a drainage operation. A beta blocker is the drug of choice. To eliminate posterior synechiae over a fair number of degrees of pupil (say 30 degrees) sector iridectomy can be done.

Aged↗
PubMed1987

Blindness in schoolchildren: importance of heredity, congenital cataract, and prematurity.

Of 99 children in the Royal Blind School, Edinburgh (which serves Scotland and part of N E England), 15 had optic atrophy (hydrocephalus 4, intracranial haemorrhage 2, prematurity 2, fetal distress 2, birth asphyxia 2, cerebral atrophy 1, cardiac arrest during hernia operation 1, and leukaemia 1). Fourteen had congenital cataract, 12 congenital retinal aplasia (Leber's congenital amaurosis) and 11 retinopathy of prematurity. There were small numbers in many other diagnostic categories, including three with non-accidental head injury. Mental retardation, spasticity, and nystagmus were frequent other correlates in all diagnostic categories. 'Very probably hereditary' was a conservative attribution in 36, while 'probable' seemed appropriate for 12-that is, almost 48% were hereditary. Only about 11 cases might have been prevented through genetic counselling, which testifies to the frequency of autosomal recessive hereditary disease, although no parents were consanguineous.

Adolescent↗
PubMed1987

Water-soluble methochloride of RU 486 fails to reduce intraocular pressure in normal rabbits.

RU 486 is a new water-insoluble drug which blocks peripheral glucocorticoid and progesterone receptors. As eye drops and by subconjunctival injection, it has been shown to lower normal rabbit intraocular pressure by a small amount. To try to improve the intraocular penetration, a water-soluble methochloride was prepared. In a series of 11 rabbits (initially 12: 1 died) treated in one eye at random with a 1% solution of the methochloride of RU 486 (vehicle drops to the fellow eye) no effect on intraocular pressure was found. The ionic nature of the methochloride may have prevented the drug becoming attached to, and blocking, the postulated glucocorticoid receptors in the rabbit outflow channels, although it may have penetrated the cornea more effectively.

Animals↗
PubMed1987

Diuretic drugs as risk factors in cataractogenesis.

The use of diuretic drugs, which previously has been found to be associated with the incidence of cataract, is further investigated to elucidate the nature of the association. Diuretic drugs with different modes of action are considered separately. The degree of association of each correlates with the mean plasma urea level which itself is associated with cataract. However, the association is with cataract in general rather than with any specific type of lens opacity.

Adrenergic beta-Antagonists↗
PubMed1986

Probably Norrie's disease due to mutation. Two sporadic sibships of two males each, a necropsy of one case, and, given Norrie's disease, a calculation of the gene mutation frequency.

Two sibships, each with two affected males but no other affected family members, are described. All four patients at birth had small eyes with white masses visible behind clear lenses. Support for a diagnosis of Norrie's disease lies in the probable mental retardation and sudden death of one child and mental retardation in the other in one of the families, and strong support in the sensorineural deafness in one child in the other family. A necropsy was performed on the dead child. Both eyes showed the retinae to be totally non-attached. The optic nerves were thin. If the diagnosis is Norrie's disease (highly probable), the birth of the second affected child in each family supports the postulate of a mutation in the X chromosome of a germ cell of a maternal grandparent or an earlier maternal ancestor, no previous member of the family having been affected. That implies a 50% risk of the disease in future male siblings and a 50% risk of the carrier state in female sibs. When only one child is affected, the explanation could also be a mutation in that individual. Given Norrie's disease, we have calculated a mutation rate of 3.9 per million chromosomes in the Scottish population--remarkably similar to the mutation rates calculated for many dominant diseases. A diagnosis of autosomal recessive non-attachment of retina implies a 25% risk to later siblings.

Blindness↗
PubMed1986

Subconjunctival suspension of RU486 lowers intraocular pressure in normal rabbits.

RU486 is both a progesterone blocker and a corticosteroid blocker (peripheral). Subconjunctival injections of 0.2 ml of a 1% suspension of RU486 powder (2 mg) were given twice weekly to one eye chosen at random of 12 rabbits. The fellow eye received the same volume, 0.2 ml, of vehicle (normal saline) only. Ocular tension was measured twice daily for six days per week by an Alcon pneumatonograph, the tonometrist(s) being unaware of which eyes were treated and which untreated. A small but significant reduction in intraocular pressure, about 0.7 mmHg, occurred in treated eyes. No intereye difference in the ocular hypertensive response to intraperitoneal injections of distilled water (50 ml/kg) was found. Clinical trials are planned in which a larger fall is expected because the trabecular meshwork in patients with open-angle glaucoma or ocular hypertension is presumably more affected by (normal) tissue levels of corticosteroid.

Animals↗
PubMed1985

Raised intraocular pressure: an alternative method of referral.

To assess delay in referring patients with suspected glaucoma two methods were studied in a randomised trial: direct referral from optician to ophthalmologist and referral through the patient's general practitioner. Direct referral was reliable for all 49 patients involved, whereas, of the 44 patients referred through their general practitioner, seven waited over three weeks for referral.

Family Practice↗
PubMed1985

Ocular hypotensive effect of late pregnancy with and without high blood pressure.

The mean ocular tension of third trimester hypertensive pregnant women did not differ significantly from that of third trimester non-hypertensives, in contrast to the tendency for open-angle glaucoma to be associated with vascular hypertension. Presumably there are different causes for the two types of vascular hypertension. The ocular hypotensive effect of late pregnancy (third trimester) was confirmed.

Adolescent↗
PubMed1985

Penetration of timolol eye drops into human aqueous humour: the first hour.

Samples of aqueous humour were removed from 26 eyes at the start of cataract extraction. Two drops of timolol 0.5% had been instilled into the conjunctival sac 12-71 minutes before operation. Analysis by gas chromatography showed a mean timolol concentration of 55.46 ng/mg, with a range of 8 to 100 ng/mg.

Aqueous Humor↗
PubMed1985

Decreased intraocular pressure and aqueous humor turnover rate during longitudinal ocular studies in the rabbit.

One group of 5 pigmented rabbits, during a period of 10 weeks, and two groups of 8 albino rabbits, during 16 weeks, showed a fall in aqueous turnover rate and outflow facility of about 30%. A fall in intraocular pressure also occurred of about 10 mm Hg. The biochemical correlative mechanism, systemic and/or local, is conjectural (reduction of "stress"; homeostasis). Empirically a parallel completely untreated control group should accompany any longitudinal study group in order to differentiate these temporal trends from experimental effects.

Animals↗
PubMed1985

Ocular fluid dynamics response to topical RU486, a steroid blocker.

A steroid antagonist applied to one eye of 18 young pigmented rabbits during a 10-week period caused a statistically significant fall in IOP, but no statistically significant nor clinically relevant change in the rate of aqueous humor turnover. The pressure change is therefore ascribed to an alteration in outflow channels. No changes occurred in a parallel group of 5 animals in which one eye was treated with vehicle and the contralateral eye was untreated. The drug effects became evident after two weeks of application, suggesting that a slow turnover pathway is involved.

Administration, Topical↗