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Biomedical subjects

R M Gwin

Publications and source records attributed to R M Gwin.

28 records · Page 2Linked to original sources
PubMed1977

Tonography in the normal and glaucomatous beagle.

A standard procedure for tonography was developed in the dog. Acepromazine, ketamine, xylazine, droperidol-fentamyl, and combinations of these drugs were evaluated for effects on blood pressure, intraocular pressure, and restraint of the dog for 4 minutes of Schiotz tonography of each eye. In dogs given a cepromazine (0.5 mg/kg intravenously) and then ketamine (10.0 mg/kg intramuscularly), the mean coefficient of aqueous humor out-flow in 24 normal Beagles was 0.24 mul/mm of Hg/minute (SD +/- 0.07). Mean coefficient of aqueous humor outflow in 35 glaucomatous Beagles, between 4 months to more than 37 months old, was 0.09 mul/mm of Hg/minute (SD +/- 0.04). Coefficient of aqueous humor out-flow was less in the older glaucomatous Beagle.

Acepromazine↗
PubMed1977

Evaluation of applanation tonometers for the dog eye.

The Mackay-Marg, pneumatonograph, TonAir, and EMT-20 tonometers were evaluated in the normal dog eye. Tonometric scale readings were compared to the manometric recordings from the anterior chamber. The Mackay-Marg tonometer evaluated in open and closed systems was the most reliable (goodness of fit [r2] = 0.96) with intraocular pressure up to 100 mm. Hg. The pneumatonograph also exhibited high reliability (r2 = 0.92) but tended to underestimate intraocular pressures above 40 to 50 mm. Hg. The TonAir and EMT-20 tonometers were the least satisfactory for the dog, with r2 of 0.77 and 0.66 to 0.81, respectively. The Mackay-Marg is the most satisfactory tonometer for the dog.

Animals↗
PubMed1977

Clinical manifestations of inherited glaucoma in the beagle.

Inherited glaucoma was exhibited in 55 beagles. The glaucomatous process was divided into early (6 to 12 months of age), moderate (13 to 30 months of age), and advanced (31 months of age). In early glaucoma the tridocorneal angles, as judged by gonioscopy, were open and without anomalies, intraocular pressure was elevated, and the tonographic facility of aqueous outflow was decreased. With moderate glaucoma, the tridocorneal angles were typically open; intraocular pressure was elevated, facility of aqueous outflow was decreased; and variable optic disc cupping and focal disinsertion of the zonules from the lens were seen. Advanced glaucoma exhibited narrow to closed tridocorneal angles, decreased facility of aqueous outflow, elevated intraocular pressure, lens dislocation, optic disc atrophy, and finally phthisis bulbi. The beagle in the early and moderate stages of glaucoma, before angle closure and lens dislocation, is an animal model for studies in open-angle glaucoma.

Animals↗
PubMed1977

The effect of topical pilocarpine on intraocular pressure and pupil size in the normotensive and glaucomatous beagle.

Topical 1, 2, and 4 percent pilocarpine were evaluated in the normotensive and glaucomatous beagles, comparing intraocular pressure (IOP), pupillary size, and time. In normotensive beagles pilocarpine produced maximal decreases of 25 percent (5.5 mm. Hg) at 1 percent concentration; 34 percent (7.26 mm. Hg) at 2 percent concentration; and 25 percent (6.9 mm. Hg) at 4 percent concentration. The maximum reductions in IOP after pilocarpine instillation in the glaucomatous beagle were 30 percent (9.1 mm. Hg) at 1 percent concentration; 44 percent (14.92 mm. Hg) at 2 percent concentration; and 31 percent (10.89 mm. Hg) at 4 percent concentration. The glaucomatous beagles responded with a greater reduction of IOP than did the normotensive beagles.

Administration, Topical↗
PubMed1977

Calibration of the Schiøtz tonometer for the normal canine eye.

The Schiøtz tonometer with 5.5-, 7.5-, and 10-g weights was calibrated for the normal canine eye, using a transducer with open and closed reservoir systems. The line of best fit for the observations was determined, and the equation of this line was utilized to derive a calibration table for the conversion of tonometer scale readings to mm of Hg intraocular pressure.

Animals↗
PubMedDate not supplied

Glaucoma in the beagle.

Glaucoma in the beagle is an inherited disease that is exhibited clinically in dogs of 6 to 18 months of age. The genealogy, clinical signs, gonioscopy, tonometry, tonography, water provocative response, and scanning electron microscopy of the iridocorneal angle of the glaucomatous beagle are summarized.

Animals↗