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Biomedical subjects

R H Stewart

Publications and source records attributed to R H Stewart.

At least 19 recordsLinked to original sources
PubMed1994

Long-term effects of glaucoma therapy with 4% pilocarpine gel on corneal clarity and endothelial cell density.

Corneal thickness measurements and endothelial cell counts were carried out in 34 patients undergoing treatment for glaucoma with 4% pilocarpine gel between 18 to 78 months after initiation of therapy. The corneal thickness and endothelial cell population were found to be within normal limits in all cases except two, one patient with increased corneal thickness who had recently undergone cataract and glaucoma filtering surgery and another patient with decreased cell count who had an old endothelial scar sustained prior to pilocarpine gel therapy. There was a very close correlation for both of these parameters noticed in patients treated with pilocarpine gel and in age-matched control group of patients with glaucoma. The present study has shown that there are no adverse corneal effects with pilocarpine gel therapy.

Adolescent↗
PubMed1993

Possible normokalemic variant of hyperkalemic periodic paralysis in two horses.

Hyperkalemic periodic paralysis (HPP), characterized by intermittent episodes of muscle fasciculations, profound muscle weakness, and hyperkalemia, has been described in Quarter Horses, Appaloosas, and Paints. In previous reports, the hallmark of this syndrome has been the development of hyperkalemia during each episode. Two affected horses had episodes of paralysis without associated hyperkalemia, demonstrating that normokalemia during an episode otherwise consistent with HPP does not eliminate HPP as a diagnosis. This clinical presentation appeared to be a variant of HPP.

Animals↗
PubMed1993

A new technique for combined cataract/glaucoma procedures in patients on chronic miotics.

We describe a combined cataract/glaucoma procedure for patients on chronic miotics that includes small-incision phacoemulsification to provide increased predictability of visual outcome and early visual rehabilitation, and an inferior pupilloplasty to facilitate intraoperative visualization. To date, 42 procedures have been performed with excellent results. Complications, although minimal, have included iridolenticular/iridocapsular adhesions, diplopia, rupture of 10-0 polypropylene sutures, peripheral anterior synechia, hyphema, and fibrinoid aqueous.

Cataract Extraction↗
PubMed1992

Complications of nasogastric intubation in horses: nine cases (1987-1989).

Pharyngeal or esophageal trauma was diagnosed in 9 horses after nasogastric intubation. Evidence of trauma (edema or ulceration) was detected in the pharynx of 3 horses and in the esophagus of 6 horses. Complications associated with nasogastric intubation were first observed in 5 horses while they were intubated and in 4 horses after extubation. Clinical signs of pharyngeal or esophageal trauma were similar, and included salivation, bruxism, coughing, and nasal discharge. Treatment, including extubation, enteral feeding through a small nasogastric tube, or esophagostomy distal to the affected site, was attempted in 6 horses. Three of 6 treated horses survived, but 4 of 5 horses with perforated esophagus were euthanatized.

Animals↗
PubMed1991

Frequency and severity of osteochondrosis in horses with cervical stenotic myelopathy.

We compared the frequency and severity of osteochondrosis lesions in young Thoroughbred horses with cervical stenotic myelopathy (CSM) vs that in clinically normal Thoroughbreds of the same age. All lesions of the cervical vertebrae and appendicular skeleton were classified histologically as osteochondrosis or nonosteochondrosis and were measured for severity. Minimal sagittal diameter was significantly smaller in horses with CSM from C2 through C6; no difference was detected at C7. Severity of cervical vertebral osteochondrosis was greater in the horses with CSM, however frequency was not different. Frequency and severity of nonosteochondrosis lesions were not different in cervical vertebrae or appendicular skeleton. Frequency and severity of appendicular skeleton osteochondrosis lesions were both greater in horses with CSM. Osteochondrosis and nonosteochondrosis lesions were more severe on facets at sites of compression than on facets at noncompressed sites in horses with CSM. However, compression was also observed at sites with no articular facet lesions. The association of widespread osteochondrosis and spinal canal narrowing with CSM suggests CSM may represent a systemic failure in the development or maturation of cartilage and bone.

Animals↗
PubMed1990

Surgical stapling for repair of a rectal tear in a horse.

A grade-4 rectal tear in a mare was successfully repaired per rectum, using a surgical stapling device. The mare had only minor postoperative complications. This technique has some advantages over previously described procedures, but should be reserved for use in selected cases.

Animals↗
PubMed1990

A double-masked three-month comparison between 0.25% betaxolol suspension and 0.5% betaxolol ophthalmic solution.

In 352 patients with primary open-angle glaucoma or ocular hypertension, a multicenter double-masked, parallel-group clinical study compared the effects on intraocular pressure and ocular comfort of 0.5% betaxolol ophthalmic solution, a cardioselective beta-adrenergic blocking agent, with 0.25% betaxolol suspension. With twice-daily dosages, baseline intraocular pressure was significantly reduced (P = .0005), with no significant difference between the two groups, at Week 2 and at Months 1, 2, and 3. Further, the prevalence of ocular discomfort upon topical instillation was significantly lower for 0.25% betaxolol suspension than for 0.5% betaxolol solution (P = .0005).

Administration, Topical↗
PubMed1990

Long-term results with the White glaucoma pump-shunt.

A White glaucoma pump-shunt was inserted in 16 eyes in 15 patients, 2 to 76 years of age (10 female and 5 male patients; 6 were white, 6 were black, and 3 were Hispanic). Six had primary open-angle glaucoma, 2 glaucoma in aphakia, 1 congenital glaucoma, 4 secondary glaucoma, 2 neovascular glaucoma, and 1 glaucoma in pseudophakia. There were no complete successes. There were five (31.3%) "qualified successes" (ie, an intraocular pressure less than or equal to 21 mm Hg on medical treatment, without pain, and without visual acuity loss of more than two Snellen lines). This qualified success rate is far below rates reported for other setons.

Adolescent↗
PubMed1989

Glare testing in cataract patients: instrument evaluation and identification of sources of methodological error.

This study sought to determine the relative sensitivity of two commercially available glare testers in predicting outdoor acuity in a population of patients with minimal cataracts. Two target optotypes were evaluated: high contrast letters and varying contrast sinusoidal gratings. Although both instruments demonstrated a significant correlation between indoor and outdoor acuity, they showed a significant difference between predicted outdoor acuity and obtained visual acuity. The brightness acuity tester on high intensity was inaccurate in predicting outdoor vision regardless of test optotype, overpredicting glare disability in 76% (average) of the study population. Glare disability overpredictions fell to 8% on the medium setting with +/- 2 lines of vision classified as "no change." Using the same criterion, the Miller-Nadler glare tester overpredicted glare disability in 2% of the cataract population but underpredicted glare disability in 62%. In this study, letter optotypes resulted in less variability than sinusoidal grating stimuli. In addition, we identify several methodological factors to consider before designing a glare experiment. These potential sources of error can influence the outcome of any glare study that compares indoor and outdoor acuity and include the study population, visual stimuli (optotypes), and elements of the outdoor testing situation.

Adolescent↗
PubMed1988

Prevention of the rise in intraocular pressure following neodymium-YAG posterior capsulotomy using topical 1% apraclonidine.

We studied apraclonidine hydrochloride (aplonidine hydrochloride or ALO 2145), an alpha-agonist, for its effect on the intraocular pressure (IOP) rise following neodymium-YAG posterior capsulotomy (YPC). In a prospective multicentered double-masked study, 63 eyes were pretreated with one drop of either 1% apraclonidine hydrochloride or placebo one hour before performing YPC and again following the laser treatment. The greatest IOP rise in the placebo-treated eyes occurred in the third hour after YPC, when the mean (+/- SD) IOP rose from a baseline pressure of 16.4 +/- 3.7 to 20.8 +/- 6.8 mm Hg. In apraclonidine-treated eyes, the IOP fell from a mean of 15.6 +/- 3.8 to 12.8 +/- 6.0 mm Hg three hours postoperatively. There were five times as many eyes that had an IOP rise greater than 10 mm Hg in the placebo-treated group compared with those treated with apraclonidine. Apraclonidine proved to be highly effective in preventing the rise in IOP following YPC.

Administration, Topical↗
PubMed1988

Suprofen treatment of contact lens-associated giant papillary conjunctivitis.

This multicenter study of patients with contact lens-associated giant papillary conjunctivitis (GPC) was a randomized, double-masked comparison of a 1.0% suprofen solution versus the suprofen vehicle solution (placebo). Patients were given two drops of medication four times daily for up to 28 days and were clinically examined on days 0, 2, 7, 14, 21, and 28. The physicians' clinical judgments of the patients' responses to therapy significantly favored suprofen over placebo at day 21 (P = 0.02), while strongly favoring suprofen at day 14 (P = 0.057) and at day 28 (P = 0.067). The patients' opinions of their response to therapy significantly favored suprofen on day 14 (P = 0.03); a trend for suprofen was evident on day 28 (P = 0.1). Treatment with suprofen led to a greater overall reduction in ocular signs and symptoms than with placebo. Strong trends approaching statistically significant levels were found for reductions in the principal ocular sign, papillae, at day 28 (P = 0.068) and in mucus strands at days 14 and 28 (P = 0.09), which also favored suprofen.

Adult↗
PubMed1988

ALO 2145 reduces the intraocular pressure elevation after anterior segment laser surgery.

The effect of an alpha adrenergic agonist, ALO 2145 (para-amino-clonidine [PAC]), was examined in a double-masked, multicenter study on the postoperative intraocular pressure (IOP) elevation after laser surgery in 165 patients (83 trabeculoplasty, 36 iridotomy, and 46 capsulotomy). One drop of 1.0% ALO 2145 or vehicle was instilled 1 hour before and immediately after laser surgery. The mean IOP increase in the ALO 2145-treated group was lower (P less than 0.05) than in the placebo group at each of the first three postoperative hours. Overall, 18% of placebo-treated eyes experienced IOP increases greater than or equal to 10 mmHg as compared with 4% of ALO 2145-treated eyes (P less than 0.003). Ocular and systemic side effects were minimal and did not differ between the treatment groups. ALO 2145 safely and effectively reduced the incidence and magnitude of potentially harmful IOP elevations after anterior segment laser surgery.

Aged↗
PubMed1988

Effectiveness of apraclonidine in preventing the rise in intraocular pressure after neodymium:YAG posterior capsulotomy.

Apraclonidine (para-aminoclonidine) is an alpha agonist that was studied for its effect on the IOP rise following YPC. In a prospective multicentered double-masked study 63 eyes were pretreated with one drop of either 1% apraclonidine or placebo 1 hour prior to performing YAG and again after the laser treatment. The greatest IOP rise in the placebo-treated eyes occurred in the third hour after YPC when the mean IOP rose from a baseline pressure of 16.4 +/- 3.7 mm Hg to 20.8 +/- 6.8 mm Hg (P less than .01). In apraclonidine-treated eyes the IOP fell from a mean of 15.6 +/- 3.8 mm Hg to 12.8 +/- 6.0 mm Hg 3 hours postoperatively (P less than .001). There were five times as many eyes that had a pressure rise greater than 10 mm Hg in the placebo-treated group compared to those treated with apraclonidine. Apraclonidine proved to be highly effective in preventing the rise in IOP following YPC.

Administration, Topical↗
PubMed1988

Lidocaine: an anti-tussive for ophthalmic surgery.

Intravenous lidocaine suppresses the cough reflex in patients undergoing local operative procedures. Many anti-tussive agents suppress the cough reflex by suppressing the respiratory center. Intravenous lidocaine produces no respiratory depression in doses that suppress the cough reflex. Intravenous lidocaine should be available during all intraocular surgical procedures so it can be used when indicated.

Antitussive Agents↗
PubMed1987

Central nervous system trauma.

Traumatic injury to the central nervous system causes immediate damage and sets in motion a complex series of pathophysiologic events that result in further neuronal injury. This secondary damage seems to be related to changes in blood flow and pressure on a systemic, regional, and microvascular level. Currently, there is evidence that these changes are, in part, mediated by endogenous opioids and arachidonic acid metabolites, namely thromboxane A2. Medical management is generally designed to intervene at one or more stages in this secondary cascade of events. Further research should lead us to better understanding of the mechanisms involved in trauma to the central nervous system and, subsequently, more specific and effective treatments.

Animals↗
PubMed1987

Medical management of spinal cord disease.

In spinal cord disease of horses, a complete history, neurologic examination, and adjunctive diagnostic procedures are very helpful in establishing a tentative diagnosis; however, a definitive diagnosis may be difficult or impossible to establish antemortem. Medical management should be initiated with full consideration of possible etiologies and knowledge of the effects and consequences of medical therapies. This article discusses the drugs commonly used in the management of spinal cord disease and the rationale for their use.

Adrenal Cortex Hormones↗
PubMed1987

A modified Gills' block and its effectiveness for lid muscle akinesia.

We developed a prospective clinical study to determine the effectiveness of a new method of retrobulbar anesthesia and akinesia of the levator and orbicularis muscles. This study involved 50 patients who underwent extracapsular cataract extractions (ECCE) with intraocular lens implant (IOL). We found levator and orbicularis muscle akinesia was achieved in 49 of 50 eyes. One reblock was necessary. We also wish to point out the advantages of this technique as a means of reducing the rare but serious complications associated with retrobulbar anesthesia.

Adult↗