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Biomedical subjects

C D Phelps

Publications and source records attributed to C D Phelps.

At least 37 records · Page 2Linked to original sources
PubMed1984

[Ocular pulse curve in glaucoma without hypertension].

The ocular pulse amplitudes were measured with a recording applanation tonometer in eyes of patients with primary open-angle glaucoma, low-tension glaucoma and in normal subjects. The mean ocular pulse amplitude of 62 eyes of 31 patients with low-tension glaucoma did not differ significantly from that of normal eyes, but there were more eyes with low and high pulse amplitudes than would be expected in a normal population. These results suggest that the patients with low-tension glaucoma did not comprise a homogeneous population, but contained one group of patients with evidence of reduced choroidal blood flow and another group with pulse amplitudes similar to those found in primary open-angle glaucoma.

Glaucoma↗
PubMed1984

A comparison of visual field loss in primary open-angle glaucoma and the secondary glaucomas.

We compared the pattern of visual field loss in 148 patients with primary open-angle glaucoma and 63 patients with secondary glaucoma. The frequency with which each location in the visual field was defective was similar in the two conditions. The most common visual field defects in both varieties of glaucoma were superior arcuate scotomas and superior nasal steps. The similar distribution of visual field defects in primary and secondary glaucomas is consistent with a common mechanism for optic disc damage.

Computers↗
PubMed1983

Baring of a circumlinear vessel in glaucoma.

We independently examined 144 optic disc stereophotographs. Despite a preliminary learning trial, we were able to agree about the presence of a circumlinear vessel in only 73% of eyes and about baring of a vessel, if present, in only 71% of eyes. Bared vessels were present in 73% of 22 glaucomatous eyes, 41% of 71 ocular hypertensive eyes, and 14% of 51 normal eyes. During several years of follow-up of 44 ocular hypertensive eyes with bared circumlinear vessels, visual field defects developed in only three. We conclude that baring of a circumlinear vessel is a difficult sign for trained observers to detect with certainty and, although present frequently in glaucoma, is of low specificity as a sign or predictor of glaucomatous damage.

Glaucoma↗
PubMed1983

Optic disk and visual field correlations in primary open-angle and low-tension glaucoma.

If the amount of visual field loss is less than expected from the amount of optic disk cupping in low-tension glaucoma compared with primary open-angle glaucoma, it might imply a difference between the two conditions in the type of optic nerve lesion produced. To test this hypothesis, three observers independently examined, in a masked fashion, optic disk stereoscopic photographs of 127 eyes with primary open-angle glaucoma and 71 eyes with low-tension glaucoma. For each stereoscopic photograph the observer predicted whether the visual field loss would be mild, moderate, or severe. The visual field were then classified, according to the number of sectors defective on the Goldmann perimeter chart, as having mild (1 to 15 sectors), moderate (16 to 30 sectors), or severe (more than 30 sectors) visual field loss. For no observer did the frequency of underpredictions or overpredictions in the two conditions differ significantly. The results of this study, thus, did not support the theory that the optic disk damage in primary open-angle glaucoma differs from that in low-tension glaucoma.

Adult↗
PubMed1982

Open angle glaucoma, ocular hypertension, low-tension glaucoma, and refraction.

An analysis of the refractions of patients with primary open angle glaucoma, ocular hypertension (OH), and low-tension glaucoma showed that myopia occurred more frequently in each group than would be expected in a normal population of similar age. One in three of the myopes with OH had glaucomatous field defects on follow-up examination, whereas the defects developed in only one in 20 of the emmetropes and in one in 40 of the hypermetropes. These results suggest that myopic eyes are more susceptible to the effects of raised intraocular pressure than are nonmyopic eyes and that myopes with OH have a particularly high risk of the development of field defects.

Adolescent↗
PubMed1982

The diagnosis and prognosis of atypical carotid-cavernous fistula (red-eyed shunt syndrome).

Nineteen patients who complained of red eyes had the characteristic clinical signs of an atypical carotid-cavernous fistula. Episcleral veins were dilated, intraocular pressure and episcleral venous pressure were high, and blood filled Schlemm's canal during gonioscopy. Most of the patients had mild exophthalmos, but in none was the exophthalmos obviously pulsatile, and in only two patients could a bruit be heard. Orbital echography disclosed either a dilated superior ophthalmic vein or congestion of the orbital soft tissues. Selective carotid angiography, done in seven patients, disclosed the fistula to be a dural-cavernous fistula. The serious complication of the fistulas was open-angle glaucoma resulting from the high episcleral venous pressure. None of the fistulas was treated surgically, but six closed spontaneously and three closed soon after carotid angiography.

Adolescent↗
PubMed1982

Effect of myopia on prognosis in treated primary open-angle glaucoma.

Visual field testing of 166 phakic eyes with optic nerve damage from open-angle glaucoma before and after one year of treatment showed that the visual fields of myopic eyes improved more often than those of nonmyopic eyes (12% vs 6%) and worsened less often (6% vs 18%). These results suggested that myopia, which adversely affects the prognosis in ocular hypertension, may facilitate the damaging effects of high intraocular pressure rather than have an independent damaging effect of its own.

Aged↗
PubMed1982

Glaucoma.

Because glaucoma is usually asymptomatic until it is far advanced, screening of susceptible individuals should be done routinely by every physician. The symptoms, signs, clinical course, and prognosis vary according to the type of glaucoma. Therefore, appropriate classification is essential to determine specific medical or surgical therapy.

Adrenergic beta-Antagonists↗
PubMed1981

Trabeculectomy vs thermosclerostomy. A randomized prospective clinical trial.

In a prospective randomized clinical trial we compared the efficacy and safety of trabeculectomy and thermosclerostomy for the treatment of open angle glaucoma. Forty-eight eyes was treated by trabeculectomy and 50 eyes were treated by thermosclerostomy. The mean follow-up period was 2.7 years. Thermosclerostomy lowered intraocular pressure about 3 mm Hg lower than trabeculectomy on the average. However, the percentage of eyes with pressures less than 22 mm Hg was not different for the two operations. The main difference between trabeculectomy and thermosclerostomy was the number of complications. Postoperative flat anterior chamber, decrease in visual acuity, cataract, hypotony, and thin bleb with late perforation or infection all occurred more frequently after thermosclerostomy. In conclusion, although trabeculectomy is slightly less effective than thermosclerostomy in lowering pressure, its relative freedom from complications make it is more desirable filtering operation.

Adult↗
PubMed1981

Acute pressure elevation following panretinal photocoagulation.

Intraocular pressure increased in 17 of 18 eyes treated for diabetic retinopathy with argon laser panretinal photocoagulation. All eyes had open anterior chamber angles before treatment. Fifteen eyes, continued to have open angles when first examined after treatment. The pressure elevation in these eyes averaged about 10 mm Hg, was detected soon after laser treatment, and persisted for several hours. Outflow facility usually was reduced. Three eyes had closed angles and elevated pressures when first examined after treatment. I addition, in five eyes that initially had open angles, angle closure developed later. Thus, the pressure elevation after extensive retinal photocoagulation usually begins with an open angle mechanism, but later may be due to angle closure as well. The reason for the pressure rise with an open angle is unknown.

Adult↗
PubMed1981

Prophylactic timolol for the prevention of high intraocular pressure after cataract extraction. A randomized, prospective, double-blind trial.

Eyes undergoing routine intracapsular cataract extraction (without alpha-chymotrypsin) often experience marked ocular hypertension in the first six hours after surgery. We conducted a randomized, prospective, double-blind study to determine if timolol maleate would prevent this increase in pressure. Thirty-five eyes undergoing routine cataract extraction were given a drop of either timolol 0.5% or placebo twice before and twice after surgery. Nine (56.3%) of 16 control eyes and 2 (10.5%) of 19 timolol-treated eyes had pressures above 30 mm Hg at six hours after surgery (P less than 0.025). Thus, prophylactic timolol 0.5% can substantially reduce the incidence of severe early postoperative ocular hypertension.

Cataract Extraction↗
PubMed1980

Glaucoma due to endothelialization of the anterior chamber angle. A comparison of posterior polymorphous dystrophy of the cornea and Chandler's syndrome.

Posteroir polymorphous dystrophy (PPMD) and Chandler's syndrome are separate ocular diseases with certain clinical features in common. Both may cause endothelial dystrophy, corneal edema, iridocorneal adhesions, and glaucoma. Differences between the two disorders include the morphology of the endothelial dystrophy, hereditary transmission, laterality, and rate of progression. Histopathologic examination of trabeculectomy and iridectomy specimens from two patients with Pmd and one patient with Chandler's syndrome disclosed a common basic pathologic process--endothelialization of the anterior chamber angle. Ectopic corneal endothelium and abnormal Descemet's membrane extended across the trabecular meshwork and onto the anterior surface of the iris. The appearance of the endothelial cells, however, was strikingly different in the two conditions. The endothelial cells in PPMD had ultrastructural characteristics of epithelial cells. Those in Chandler's syndrome were degenerated but retained ultrastructural features of endothelial cells.

Anterior Chamber↗
PubMed1979

Rieger's syndrome. A case report with a 15-year follow-up.

A 15-year follow-up examination of a boy with Rieger's syndrome showed that the anterior segment changes in this disease may be slowly progressive in the absence of glaucoma or miotic treatment. The patient also had two recently recognized systemic features of the syndrome, umbilicus cutis and hypospadias.

Adolescent↗
PubMed1979

Intraocular pressure in retinal detachment.

Relative hypotony in the affected eye was present in 40% of patients with uncomplicated unilateral retinal detachments. The average pressure asymmetry was only 1.3 mm Hg, but in one out of every four patients the difference was 3 mm Hg or more. In a control group, such a difference occured in only one out of every twenty patients. Relative hypotony persisted for longer than six months after scleral buckling operation, occuring even in patients that did not exhibit hypotony preoperatively.

Humans↗
PubMed1978

Ocular hypotony following retinal vein occlusion.

In a study of 130 cases of unilateral retinal vein occlusion uncomplicated by rubeosis, we found that more than 80% of the patients had a lower intraocular pressure (IOP) in the eye with the occlusion than in the fellow normal eye. The reduction of IOP was greater with central than with branch vein occlusion, greater with hemorrhagic than with venous stasis retinopathy, and greater in patients who had high pressures in their fellow eyes. The pressure reductions persisted during follow-up periods of up to two years. How retinal vein occlusion lowers IOP is obscure and may involve more than one mechanism. Outflow facility was increased (compared to the fellow eye) in hemorrhagic retinopathy and in branch vein occlusion, both of which are association with retinal ischemia, but not in venous stasis retinopathy. Calculated rates of aqueous formation were low in central vein occlusion but not in branch vein occlusion.

Adult↗
PubMed1978

Measurement of episcleral venous pressure.

Using materials available in any ophthalmology clinic, we constructed a useful and reliable instrument for measuring episcleral venous pressure. The instrument, a modification of the pressure chamber method of Seidel, utilizes a latex membrane and an air-filled chamber. These modifications facilitated ease of preparation for the measurement. Episcleral venous pressure in normal subjects was 9.0 +/- 1.6 mm Hg (mean +/- S.D.). Measurement of episcleral venous pressure facilitated diagnosis of diseases such as arteriovenous fistula and superior vena caval obstruction, which block drainage of venous blood from the orbit.

Adult↗