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Biomedical subjects

A M Glenn

Publications and source records attributed to A M Glenn.

10 recordsLinked to original sources
PubMed1997

Heparinised intraocular infusion and bacterial contamination in cataract surgery.

BACKGROUND/AIMS: Heparin in solution reduces bacterial adhesion to intraocular lenses and a lower incidence of postoperative endophthalmitis has been reported with the use of heparin coated lenses. The safety of adding low molecular weight heparin to the infusion fluid during routine cataract surgery was investigated. Any direct antibacterial effect was looked for by culturing anterior chamber fluid samples taken at the completion of surgery. METHODS: A randomised, double blind, controlled study of 111 patients undergoing routine cataract surgery. Low molecular weight heparin at a concentration of 5 IU/ml was added to the infusion fluid in the trial patients. Samples from the anterior chamber taken at completion of surgery were cultured. Twenty nine samples of sterile infusion fluid were also cultured as further controls. RESULTS: No complications were found in either group, and no difference in observed postoperative inflammation in each group. In the heparinised group (n = 55) bacterial contamination was found in 31% of samples, compared with 27% in the no heparin group (n = 56) (no significant difference). CONCLUSIONS: There appears to be no direct antibacterial effect of heparin, and other possible mechanisms of action are discussed. Heparin avoids many of the drawbacks of traditional antibiotic prophylaxis and may have the potential to be a safe and effective addition to endophthalmitis prevention.

Aged↗
PubMed1994

Effect of vitamin A treatment on the prolongation of dark adaptation in Stargardt's dystrophy.

BACKGROUND: Prolongation in recovery of rod thresholds has been demonstrated in Stargardt's dystrophy. One possible explanation for this finding includes an impairment of vitamin A transport by the retinal pigment epithelium (RPE). By delivering an increased amount of vitamin A to the RPE, it might be possible to overcome a relative deficiency of vitamin A utilization or transport, and thus improve rod dark adaptation. METHODS: Baseline dark-adapted rod final thresholds were measured for five patients with Stargardt's dystrophy after 60 minutes of dark adaptation. A full dark-adaptation curve was then measured after exposure to a bleaching light for 5 minutes. Time of recovery to within 0.2 log units of the prebleach dark-adapted rod threshold was determined. Each subject then took a 14- to 18-day course of oral vitamin A, 50,000 IU daily. Dark adaptation was then reassessed using the same pretreatment protocol. RESULTS: Before treatment, all five patients had a prolongation of their rod recovery curve. There was no statistically significant difference between subjects in mean time taken to reach prebleach rod baseline thresholds before and after vitamin A treatment. CONCLUSIONS: These findings do not rule out the possibility that a delay in rod dark adaptation in Stargardt's dystrophy results from an inability to transport vitamin A from the RPE to photoreceptor cells. Nevertheless, a high dose of oral vitamin A taken for at least 14 days did not provide any objective improvement in dark-adaptation function in five such patients.

Administration, Oral↗
PubMed1994

Dark adaptation in patients with Best vitelliform macular dystrophy.

Psychophysical dark adaptation studies were performed in six patients with Best vitelliform macular dystrophy (BVMD) using a Goldmann-Weekers dark adaptometer. Prebleach thresholds were determined before obtaining a postbleach full recovery curve. Unlike patients with Stargardt macular dystrophy, all patients with BVMD showed a normal time to reach their baseline dark adapted thresholds after bleaching of their rod visual pigment when tested in clinically normal appearing retina. Although a lipofuscin material accumulates within retinal pigment epithelial cells in patients with either Best or Stargardt dystrophy, functional findings pertaining to recovery of rod dark adaptation thresholds as well as electro-oculogram light peak to dark trough ratios are different in these two disorders.

Adolescent↗
PubMed1993

Rebound of macular edema with continued use of methazolamide in patients with retinitis pigmentosa.

PURPOSE: To assess the effect of methazolamide on chronic macular edema in patients with retinitis pigmentosa in a double-masked, placebo-controlled, crossover study. Three subjects who had an initial improvement in their macular edema as demonstrated on fluorescein angiography received a continued course of methazolamide to assess its effect on macular edema. METHODS: Seventeen subjects were enrolled in the initial study. On angiography, nine subjects demonstrated improvement in their macular edema with the use of methazolamide for 3 weeks; three of these continued receiving the drug at a dosage of 50 mg twice daily for either an additional 6 (one subject) or 12 (two subjects) weeks. All subjects were assessed at each visit with fluorescein angiography and on best corrected visual acuity, both undilated and dilated; a subjective impression was also documented. RESULTS: After 6 and 12 weeks of treatment, all three subjects experienced a rebound of angiographic macular edema to some extent. The visual acuity varied only slightly (up to 7 letters) from both the baseline and most recent examinations after 6 and 12 weeks of treatment. CONCLUSION: Results from these few subjects suggest that at least a partial rebound of macular edema seen angiographically may occur with the continued use of methazolamide in patients with retinitis pigmentosa and chronic macular edema. Further study is required to determine if this rebound effect also occurs in treatment of other ocular disorders with chronic macular edema.

Adult↗
PubMed1993

Visual acuity in patients with best vitelliform macular dystrophy.

PURPOSE: Forty-seven patients with Best vitelliform macular dystrophy were evaluated in a cross-sectional fashion for visual acuity loss with age. METHODS: The authors assessed only patients who had at least one eye with a recognizable phenotype of Best vitelliform macular dystrophy. Patients with absent foveal changes or with only minimal foveal pigment mottling and hypopigmentation in each eye were excluded. RESULTS: A significant difference was noted between the visual acuities of the two eyes of the patients (2 lines or greater in the majority [64%] of patients). Nevertheless, for both eyes a significant correlation was noted between patient age and visual acuity, with older patients tending to have worse visual acuities. In the eyes with the best visual acuity, the majority of patients younger than 40 years of age (76%) had a visual acuity of 20/40 or better. In patients older than 30 years of age, a substantial percentage (74%) had a visual acuity of 20/100 or worse in at least one eye. CONCLUSION: The authors' findings indicate that although patients with Best vitelliform macular dystrophy who show characteristic macular lesions may retain good visual acuity in at least one eye, an appreciable number can lose substantial visual acuity, at least monocularly. In this population, no patient older than 50 years of age fulfilled the visual acuity criterion of 20/40 in at least one eye, the requirement in most states for an unrestricted driver's license, and only 20% of patients older than 40 years of age fulfilled this visual acuity criterion.

Adolescent↗
PubMedDate not supplied

Exposure hypothermia and the winter sports SCI participant.

Sensation is impaired in the individual with a complete spinal cord injury and it can be compromised in those with incomplete lesions. Quadriplegics and high paraplegics are, therefore, susceptible to environmental temperature changes (partially poikilothermics). Physicians have assumed that SCI persons engaged in winter sports activities are sensitive to exposure hypothermia. To test this premise, participants were examined within five minutes following their arrival from the ski slopes. Sublingual temperature, pulse and respirations were obtained from nine participants. Exposure hypothermia was found in one-third of the selected individuals. We concluded that exposure hypothermia is one of the complications to look for in the winter sports SCI participant, and that cases could be misdiagnosed if physiological knowledge of the SCI person is lacking.

Adult↗