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Biomedical subjects

M A Kass

Publications and source records attributed to M A Kass.

At least 19 recordsLinked to original sources
PubMed1992

Gonioscopic ab interno laser sclerostomy. A pilot study in glaucoma patients.

PURPOSE: The purpose of this study is to evaluate the safety and efficacy of gonioscopic ab interno laser sclerostomy (GLS) in patients with glaucoma. METHODS: The technique of GLS involves iontophoresis of methylene blue dye (1%) at the limbus to focally dye the sclera and to provide subsequent delivery of 10-microsecond pulsed laser energy to the dyed area through a goniolens. The laser emits at 660 nm, a wavelength that is maximally absorbed by the methylene blue dye. Patients were evaluated for fistula formation, intraocular pressure (IOP) reduction, and adverse sequelae. Thirty-eight treatments were performed in 35 eyes. RESULTS: Successful complete sclerostomies were achieved in 21 eyes (55%), which was associated with an acute mean reduction in IOP of 23 mmHg. Mean preoperative IOP for all patients was 35 mmHg, and 1 hour after treatment it was reduced to 18.5 mmHg. In 4 of the 38 treatments, there was no acute IOP reduction, and these eyes were judged as failures. The mean follow-up time was 8.2 months with a maximum follow-up of 15 months. By 9 months, 50% of patients had an IOP of 22 mmHg or lower. The number of antiglaucoma medications decreased from 3.1 to 1.7 for all eyes over the 15-month follow-up period. Hyphemas (13%) were the only major complication, and these resolved spontaneously. In only one case did the IOP increase after the procedure. CONCLUSION: The results of this trial indicate that GLS is technically feasible, and preliminary results of IOP control are promising.

Adult↗
PubMed1979

Timolol maleate: efficacy and safety.

A randomized, double-masked trial of various concentrations of timolol maleate ophthalmic solution (0.1%, 0.25%, 0.5%, and 1.0%) vs placebo demonstrated that all concentrations of timolol effectively lowered intraocular pressure (IOP). A 0.5% solution of timolol was as effective in reducing IOP as the 1.0% concentration. Blood pressure, visual acuity, and pupillary diameter were not altered significantly by any concentration of timolol tested during this study. There was a dose-dependent decrease in resting pulse rate with increasing concentrations of timolol. No objective signs of drug intolerance were found on external ocular examination, nor were any subjective symptoms elicited on questioning the subjects. Timolol applied topically twice daily in concentrations of 0.1% to 0.5% appeared to be an effective and safe ocular hypotensive agent.

Adult↗
PubMed1979

Multivariate analysis of the risk of glaucomatous visual field loss.

In a retrospective study, 92 patients with ocular hypertension, ie, intraocular pressure of 21 mm Hg or higher, and no evidence of glaucomatous visual field defects, were observed for five years. Visual field defects developed in one or both eyes of 33 patients during the five-year follow-up period, while none were detected in the remaining 59. Values for suspected risk factors, determined at the outset of the follow-up period, were subjected to a multivariate analysis with use of linear discriminant analysis and a multiple logistic function. Models of risk providing maximum separation of the two patient groups (visual field loss vs no visual field loss) found that the risk factors having the greatest significance for prediction of visual field loss included vertical estimates of cup/disc ratio, mean IOP during the period of observation, a positive family history of glaucoma, and age. Factors having the lowest predictive values included IOP response to topical dexamethasone, plasma cortisol suppression, and a history of systemic hypertension.

Glaucoma↗
PubMed1979

Dipivefrin and epinephrine treatment of elevated intraocular pressure: a comparative study.

Every 12 hours 0.1% dipivefrin was administered to one eye and 2% epinephrine hydrochloride was administered to the fellow eye of 42 patients with primary open-angle glaucoma or ocular hypertension in a randomized, double-masked study lasting three months. Dipivefrin produced similar percent reductions in intraocular pressure (18.6%) to epinephrine (21.0%), as well as similar increases in outflow facility and pupil diameter. A significantly lower incidence of burning and stinging after drug instillation was noted with dipivefrin therapy. This study supported the contention that dipivefrin is an effective and safe alternative to epinephrine therapy for the reduction of elevated intraocular pressure.

Adult↗
PubMed1979

Efficacy and patient acceptance of pilocarpine gel.

Fifteen patients with symmetrically increased intraocular pressure (IOP) participated in a single-masked random 30-day clinical trial comparing 4% pilocarpine hydrochloride gel applied at bedtime to one eye with 4% pilocarpine hydrochloride drops instilled four times daily in the fellow eye. Both forms of pilocarpine reduced IOP significantly at 8 A.M., 12 noon, and 4 P.M. (P less than .01). At these times there was no significant difference in effect between the two forms of pilocarpine (P greater than .05). The mean IOP of eyes treated with gel showed no significant difference from the pretreatment value at 10 P.M. (P = .37), whereas at this time eyes treated with drops did maintain a significant IOP reduction (P = .02). At 10 P.M. pilocarpine drops reduced IOP significantly more than did pilocarpine gel (P = .002). Pupil diameter was affected by the gel and drops in a similar pattern to that of IOP. Patients tolerated the gel with few side effects and were pleased by the convenience of administration once daily.

Administration, Topical↗
PubMed1979

Prostaglandin and thromboxane synthesis by microsomes of rabbit ocular tissues.

Microsomes of albino rabbit ocular tissues were incubated with (1-14C)-arachidonic acid for 15 min at 37 degrees C. Thin-layer chromatography revealed that ciliary body-iris microsomes were capable of synthesizing prostaglandin F2alpha (PGF2alpha), PGE2, PGD2, thromboxane B2(TXB2), and 6-keto-PGF1alpha. Indomethacin 14 micrometer in the incubation medium essentially abolished all prostaglandin synthesis detectable by this method. Imidazole 10 mM in the incubation medium inhibited only TXB2 synthesis. Ciliary body-iris microsomes were incubated for 2 min at 0 degrees C with PGH2. The products of this reaction were superfused over spiral strips of rabbit aorta and produced the strong contractions typical of TXA2. Addition to imidazole to the incubation medium blocked the formation of the contracting substance. Incubation of ciliary body-iris microsomes with (1-14C)--8,11,14-eicosatrienoic acid produced PGF1alpha, PGD1, and PGE1 but no evidence of any thromboxane product or 6-keto-PGF1alpha. Conjunctival and corneal microsomes synthesized prostaglandins, although less effectively than ciliary body-iris microsomes, when incubated with (1-14C)-arachidonic acid. Microsomes of sclera, retina-choroid, and lens synthesized little, if any, prostaglandins.

8,11,14-Eicosatrienoic Acid↗
PubMed1978

Increased corneal thickness simulating elevated intraocular pressure.

A 17-year-old girl had intraocular pressure readings of 30 to 40 mm Hg in both eyes, with normal visual fields and optic nerve heads. Medical treatment was unsuccessful in lowering the IOP measurements substantially. The central corneal thickness was 0.90 mm in each eye in the absence of corneal edema. Cannulation of the left anterior chamber revealed an IOP of 11 mm Hg, while the Perkins' and Schiŏtz' tonometers gave readings of 35 and 34 mm Hg, respectively. Previously, elevated tonometry readings had been obtained by Goldmann's, Perkins', Schiŏtz', MacKay and Marg's, pneumatic tonometer and air puff tonometer. This suggested that measurement of central corneal thickness be performed in cases in which IOP recordings do not correspond to other clinical findings.

Adolescent↗
PubMed1978

A simplified test of epinephrine responsiveness.

Forty-three ocular hypertensive and 33 ocular normotensive subjects received two doses of topical 1% epinephrine hydrochloride in one eye. The epinephrine was administered twice, ie, at time "zero" (8 AM) and 12 hours later (at 8 PM). The mean intraocular pressure responses at four hours and at 24 hours (12 hours after the last dose of epinephrine) were significantly correlated, r = 0.59 (P less than .001). This suggested that the simpler four-hour test was an equally accurate measure of the ocular responsiveness to topical epinephrine.

Epinephrine↗
PubMed1978

Intraocular pressure response to topical epinephrine and HLA-B12.

Twenty high responders to topical corticosteroids (intraocular pressure greater than 31 mm Hg after six weeks of topical 0.1% dexamethasone, four times daily) and 20 low responders (IOP less than 20 mm Hg) of similar age, sex, race, initial IOP, and facility of outflow were selected. After 24 hours of treatment (two doses) of topical 1% epinephrine hydrochloride, the high corticosteroid responders showed a mean (+/-SD) corrected decrease in IOP of 3.6 +/- 2.0 mm Hg as opposed to 1.8 +/- 2.1 mm Hg in the low corticosteroid responders. Within both corticosteroid groups, individuals with the antigen HLA-B12 showed significantly greater decreases in IOP. This suggested that the presence of HLA-B12 was not only associated with increased responses to corticosteroids but also to epinephrine.

Administration, Topical↗
PubMed1978

Histocompatibility antigens and primary open-angle glaucoma. A reassessment.

Histocompatibility (HLA) antigen typing was performed on 306 patients who had been studied and classified carefully. Black individuals with primary open-angle glaucoma (POAG) had no significant differences in HLA antigen prevalences from black control subjects. In one white population with POAG, a significant decrease in HLA-A1, a significant increase in HLA-Aw31, and a significant increase in the antigen combination HLA-B7 and HLA-Bw22 were noted. However, these differences were not confirmed in a second white population with POAG. We concluded that associations between the A and B loci of the HLA antigen system and POAG were not as impressive as has been previously reported.

Black People↗
PubMed1978

Quantitative visual field and optic disc correlates early in glaucoma.

A retrospective study was made of persons with ocular hypertension and normal initial visual fields. Seventy eyes were followed, and glaucomatous visual field defects developed in 25 of these eyes. In eyes with ocular hypertensio, the area enclosed by the central visual field isopter (I2e) was significantly smaller than that previously reported for an age-corrected group of eyes with normal intraocular pressure. In the absence of glaucomatous visual field defects, isopter areas were not releated to cup-disc ratios. Coincident with visual field loss, reductions in both peripheral (I4e) and central (I2e) isopter areas correlated linearly with increases in the cup-disc ratio. Prior to visual field loss, the I4e isopter area wassignificantly smaller among those eyes destined to lose visual field.

Adult↗
PubMed1978

Intraocular pressure and glaucoma in the Zuni indians.

A glaucoma-screening examination was performed on 119 full-blooded Zuni Indians and 286 control subjects who were aged 40 years or older. The mean intraocular pressure (IOP) of the Zuni Indians was significantly lower than that of the control group, adjusted for age and sex differences, in both diabetic and nondiabetic subjects. The control group demonstrated an increasing IOP with age, while the Zunis did not. The prevalence of ocular hypertension was significantly greater in the control group than in the Zunis. The majority of the Zuni subjects with ocular hypertension had diabetes mellitus. None of the Zuni Indians who were screened had primary open-angle glaucoma and none had a family history of glaucoma.

Adult↗
PubMed1978

Retail cost of antiglaucoma drugs in two cities.

Volunteer shoppers purchased antiglaucoma medications dispensed from prescriptions written according to generic and brand-name products in Manhattan and in the St. Louis area. All drugs obtained were more expensive in Manhattan than in St. Louis. No significant cost difference was found between generic and brand-name items in either city, but only in a few instances were generic drugs actually dispensed. No difference in overall price was found between pharmacies located in better and poorer neighborhoods in Manhattan or between pharmacies located in urban, suburban, or rural areas in St. Louis. A white shopper paid significatnly lower retail prices than did a Hispanic shopper in Manhattan, particularly in better neighborhoods. The range of prices in each city for all drugs studied was greater than twofold. Pharmacies offering more patient services tended to charge higher prices, but frequently, pharmacies did not actually offer the services they advertised.

Drug Prescriptions↗