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Biomedical subjects

J C Merritt

Publications and source records attributed to J C Merritt.

At least 37 records · Page 2Linked to original sources
PubMed1982

Orthostatic hypotension after delta 9-tetrahydrocannabinol marihuana inhalation.

3 male glaucoma subjects experienced orthostatic hypotension within 10 min after completing 2% delta 9-THC ranging from 57 to 233 ng/ml were found 5 min after smoking. Peripheral venodilation appeared responsible for the precipitous decrease in systolic blood pressure in all 3 subjects. These orthostatic episodes which clinically simulated the typical 'faint' were characterized by the absence of tachycardia and their relief by assuming a reclining position. The postural hypotension occurred despite differences in inhalation technique, level of delta (9)-THC present in plasma, previous marihuana experience of body habitus.

Adult↗
PubMed1982

Lensectomy-vitrectomy for stage V cicatricial retrolental fibroplasia.

Ten infants (18 eyes) blind from stage V cicatricial retrolental fibroplasia were examined from January 1978 to January 1981 at North Carolina Memorial Hospital. The early perinatal factors which may have predisposed to the binding end-stage cicatrix are identified. To increase their visual potential and to prevent secondary angle closure glaucoma, 12 lensectomy-vitrectomies were performed on 12 eyes (eight infants). One eye (one infant) had a pars plana vitrectomy without lensectomy. Seven eyes (seven infants) were not operated. Five of these eyes (five infants) had stage VRLF while two eyes (two infants) remained stable at stage II RLF. All retinas remained detached immediately after surgery. Secondary vitrectomies with air injections (three eyes, two infants) similarly failed to attach any retinas. Adherence of ciliary epithelium to clear lens and retrolental membrane as visualized within the dilated pupil (Eifrig-Merritt sign) was an intra-operative indicator of imminent surgical failure. Two eyes (two infants) developed early vitreous hemorrhages, hyphemas, secondary glaucoma, and phthisis bulbi within 12 months. Follow-up data were unavailable on two infants. Blindness secondary to cicatricial retrolental fibroplasia is increasing due to increased survival of low birthweight premature infants. Since surgical visual rehabilitation is not possible after the retrolental cicatrix has formed, the risk factors common to this high risk population should prompt preventive therapies.

Cicatrix↗
PubMed1980

Effect of marihuana on intraocular and blood pressure in glaucoma.

Marihuana inhalation was accompanied by increased heart rate and decreased intraocular and blood pressure in 18 subjects with heterogenous glaucomas. The hypotensive effects appeared in 60 to 90 minutes as the decrease in intraocular pressure (IOP) appeared to follow the decrease in blood pressure. In addition to any local effect, the mechanism of lowered to any local effect, the mechanism of lowered IOP may also involve the decreased pressure perfusing the ciliary body vasculature as a result of the peripheral vasodilatory properties of marihuana. Postural hypotension, tachycardia, palpitations, and alterations in mental status occurred with such frequency as to mitigate against the routine used in the general glaucoma population. Our data indicate that further research should be directed to local means of delivering the ocular hypotensive cannabinoid to the glaucomatous eye.

Adult↗
PubMed1980

Conjunctival biopsy in sarcoidosis.

Excisional biopsy, under slit lamp visualization, makes conjunctival biopsies a viable alternative to bronchoscopy as the initial diagnostic step. The authors report their experience on excisional biopsies of the palpebral conjunctiva in 16 patients suspected of having sarcoidosis.

Adolescent↗
PubMed1980

Filtering procedures in American blacks.

A single filtering operation was performed on 46 eyes of 28 American black patients with varying forms of glaucoma. An operation was considered successful when the intraocular pressure was below 22 mm Hg six months after surgery on no further medications. Of the 36 eyes with six months follow-up eight (22%) had IOP below 22 mm Hg on no further medication. The remaining 28 eyes (78%) required the addition of glaucoma medications to control the pressure. Conjunctival scarring of the filtering bleb occurred rapidly in most failures though the mechanisms by which these closures occur remain obscure. Topical steroids and cycloplegia did not significantly alter the course of this increased failure rate in American blacks.

Adult↗
PubMed1979

Bacillus cereus panophthalmitis after intravenous heroin.

Two healthy young black men developed panophthalmitis after intravenous heroin injections. Bacillus cereus, considered to be a relatively noncommon pathogen for man, was found to be the causative agent as it was recovered from the anterior chamber and viterous cavity of both cases. The ocular findings were unilateral in each case, and neither patient had any sistemic involvement from the bacteremia. The onset of visual symptoms varied from 24 to 36 hours after the last intravenous injection with the eye becoming rapidly blind. Photographs of the early fundus lesions included preretinal hypopyon-like lesions and peculiar changes in the blood vasculature. Intracameral gentamicin and steroids did not alter the cause, and treatment was enucleation.

Adult↗
PubMed1979

Effects of tetrahydrocannabinol on arterial and intraocular hypertension.

Clinical studies were conducted to determine the relationship between simultaneous changes in heart rate, blood pressure, and intraocular pressure in systemic normotensive (N=8) and hypertensive (N=8) open-angle glaucoma patients (N=16) after inhalation of tetrahydrocannabinol (THC). Insignificant changes occurred in arterial and ocular pressures after placebo pertubations. The functional responses after 2.8% THC inhalation in sitting normotensive and hypertensive patients included invariable increases in heart rate (range 20-62 beats/min greater than control) followed by substantial decreases in systolic pressure (range 12-52 mmHg less than control), diastolic pressure (range 6-28 mmHg less than control), and intraocular pressure (range 6-21 mmHg less than control). The intensity and duration (3-4 hours) of the arterial and ocular pressure responses to THC were greater in hypertensives than in normotensive patients. The salient observation after THC inhalation was that the changes in ocular pressure paralleled the changes in blood pressure in each glaucoma patient. These findings suggest that the positive chronotropic response to THC tends to maintain cardiac output which limits further decreases in blood pressure and the capillary filtration of aqueous humor decreases or the reabsorption of aqueous humor increases because of the systemic hypotensive effect attending THC inhalation.

Aged↗
PubMed1979

Endogenous uveitis in children.

Endogenous uveitis, with its ocular sequalae, accounts for a significant number of blind children in the world today. Even though these children are asymptomatic by ophthalmic history, they usually present with ocular pathology compatible with chronic intraocular inflammation. Although loss of vision is invariably due to cataract formation, fluorescein angiogram, binocular indirect ophthalmoloscopy, and fundus contact lens examination often reveal pathology of the optic nerve and retina, accounting for a significant degree of visual loss. While actual etiologic agents are usually not identified in the majority of children, toxoplasmosis, sarcoidosis, and childhood arthropathies occur with such high frequency that mention is made of these diseases. Conventional surgical procedures for ocular sequalae such as cataract and glaucoma, are known to yield poor results. Corticosteroids administered either topically, periocularly, or systemically appear to be of value in the treatment of these diseases, although control studies have not been done. Efforts to lessen the visual morbidity in these children should begin by a cross-fertilization of information between primary care physicians, pediatricians, and ophthalmologists.

Adrenal Cortex Hormones↗
PubMed1979

Diurnal intraocular pressure in juvenile open-angle glaucoma.

Outpatient diurnal intraocular pressures were obtained on 10 patients with juvenile open-angle glaucoma at approximately 6 hour intervals. There were 8 males and 2 females with an age range of 19 to 38 years. All glaucomatous medications were stopped 24 hours before recording the tensions. The peak intraocular pressure was recorded at the 6 PM interval in 6 of the 10 patients. Three patients recorded their highest pressures at the 12 AM (midnight) interval. Extraordinarily wide angles were observed in all cases and myopia was a common refractive error. Although the family history was not known in 3 patients, there was a positive family history of glaucoma in 7 of the 10 patients, which suggests an autosomal dominant mode of inheritance.

Adult↗
PubMed1978

Adult cytomegalic inclusion retinitis.

Two cases of adult cytomegalic inclusion retinitis are described in renal transplant patients. The areas of initial involvement by the retinitis were left atrophic and demarcated from normal retina by a hypopigmented area in the retina. Both cases were complicated by the development of a secondary glaucoma with open angles. The glaucoma in each patient was successfully managed by carbonic anhydrase inhibitors, epinephrine drops, and cycloplegias. One patient still retains normal visual acuity in the eye which had active retinitis.

Adult↗
PubMed1977

Malignant glaucoma induced by miotics postoperatively in open-angle glaucoma.

A case of malignant glaucoma that developed in a patient with primary open-angle glaucoma is described. The malignant course was induced during the immediate postoperative period by the inadvertent use of miotics. The malignant course was successfully managed by osmotic agents, acetazolamide, cycloplegics, mydriatics, and topical steroids.

Female↗
PubMed1976

Transpupillary photocoagulation of the ciliary processes.

We used transpupillary argon laser to photocoagulate the ciliary processes in 7 eyes of 6 patients in an attempt to reduce intraocular pressure. Only one patient showed a decrease in intraocular pressure to a normal level. This patient was the only one in this series in whom large numbers of ciliary processes could be coagulated. The limiting factor in effective transpupillary argon laser photocoagulation may, therefore, be the total number of ciliary processes visualized and treated.

Ciliary Body↗