Biomedical subjects
Christopher Girkin
Publications and source records attributed to Christopher Girkin.
Statins and other cholesterol-lowering medications and the presence of glaucoma.
OBJECTIVE: To explore whether oral statin and other antihyperlipidemic medications are associated with open-angle glaucoma. METHODS: The administrative clinical databases maintained at the Veterans Affairs Medical Center, Birmingham, Ala, were used to conduct a matched case-control study. Cases were all male patients aged 50 years and older with a new diagnosis of glaucoma on an outpatient or inpatient visit during the period January 1, 1997, through December 31, 2001. Ten control subjects were matched to each case according to age (within 1 year). Prescription files were assessed for statin use as well as additional medications to lower cholesterol levels. Information on comorbid medical conditions was also obtained. Conditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Longer duration of statin use was associated with a lower risk of open-angle glaucoma (P for trend =.04) primarily among subjects with 24 months or more of use (OR, 0.60; 95% CI, 0.39-0.92). When stratified by comorbid medical condition, among those with cardiovascular disease (OR, 0.63; 95% CI, 0.42-0.97), lipid metabolism disorders (OR, 0.63; 95% CI, 0.41-0.99), and the absence of cerebrovascular disease (OR, 0.76; 95% CI, 0.58-0.99), statins demonstrated a protective effect on open-angle glaucoma. Finally, a protective association was also observed among those who used nonstatin cholesterol-lowering agents (OR, 0.59; 95% CI, 0.37-0.97). CONCLUSIONS: Initial examination of an administrative clinical database indicates the intriguing possibility that long-term use of oral statins may be associated with a reduced risk of open-angle glaucoma, particularly among those with cardiovascular and lipid diseases. Nonstatin cholesterol-lowering agents were also associated with a reduced risk of having open-angle glaucoma. Additional investigation is warranted as to whether these classes of agents may provide an additional therapeutic addition for glaucoma.
A randomized, placebo-controlled, crossover clinical trial of super blue-green algae in patients with essential blepharospasm or Meige syndrome.
PURPOSE: To evaluate the effectiveness of super blue-green algae (SBGA) supplements on the severity of essential blepharospasm treated with botulinum toxin A injections. DESIGN: Double-masked, placebo-controlled, two-period, crossover randomized trial. PATIENTS AND METHODS: The study was carried out in patients with essential blepharospasm or Meige syndrome undergoing routine treatment with botulinum toxin A injections. INTERVENTION: Patients were randomly assigned to either SBGA capsules or placebo. After 6 months of treatment, patients underwent a 6-month washout period with no treatment, then were administered the alternate treatment for an additional 6 months, thus serving as their own controls. MAIN OUTCOME MEASURES: Video documentation of blink rate and involuntary facial movements, time between botulinum toxin A injections, and patients' subjective assessment of the impact of blepharospasm on functioning were obtained at the beginning and end of the first and second (crossover) treatment periods. RESULTS: A total of 24 patients (10 men, 14 women; aged 42 to 83 years) completed both treatment periods. Mean within-patient difference in blink rate between SBGA and placebo periods was -2.1 blinks per 2 minutes (95% confidence interval [CI]: -20.8-+31.9), not statistically different from zero (P =.83). Mean within-patient difference in time between injections between SBGA and placebo periods was 4.6 days (95% CI: -13.3-+22.5), not statistically different from zero (P =.62). The lack of statistical significance may have been because of small sample size. There were no significant differences in severity of involuntary movement between SBGA and placebo treatment periods. However, patients were more likely to report limitation in function during the period they took SBGA than during the period they took placebo (odds ratio, 0.2; P =.03). CONCLUSION: Overall, we found no evidence of a beneficial effect of SBGA as an adjunct to botulinum toxin A injections; however, a few patients, all younger than 60 years, did appear to benefit from SBGA.
Thin corneas and the risk of progression.
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Emerging perspectives in glaucoma: optimizing 24-hour control of intraocular pressure.
PURPOSE: To explore recent studies and clinical experience involving the importance of 24-hour control of intraocular pressure (IOP) in patients with glaucoma. METHODS: Roundtable discussion. RESULTS: During the discussion, the following concepts were identified: 1. Although the effect of IOP is continuous, IOP is infrequently measured in clinical practice. 2. Within an individual patient, measurements of IOP have considerable variability throughout 24 hours. 3. Recent studies have shown that healthy subjects and glaucoma patients may experience their highest IOP at night once they have lain down to sleep. 4. Low blood pressure levels related to an individual's circadian rhythm can occur simultaneous with high IOPs at night, reducing blood flow to the optic nerve head below critical levels and thus resulting in optic nerve damage. 5. Glaucoma medications that can maximally reduce IOP over 24 hours and minimally influence blood pressure should have theoretical and practical advantages for glaucoma management. CONCLUSIONS: The new knowledge about peak night-time IOPs is changing how physicians manage their patients in terms of drug selection and targeted IOP levels aimed at halting progression of glaucomatous optic nerve damage and visual field loss. Physicians are also taking into consideration the troublesome relationship between lowered systemic blood pressure and elevated IOP during the nighttime period.
Aging-related changes in the multifocal electroretinogram.
The multifocal electroretinogram (MERG) was recorded in the central 36 degrees-diameter field in 26 young (19-30 yr) and 20 old (60-74 yr) adults in normal retinal health according to a fundus grading scale. The mean amplitude densities of the first-order and second-order responses in this retinal region were lower for old adults compared with young. The aging-related reduction of the first-order amplitude density was greatest at the fovea and decreased as a function of eccentricity. Similarly, the amplitudes of the first negative and positive peaks of the first-order MERG waveform were reduced with age, and the pattern of reduction followed a similar eccentricity dependency. The aging-related changes in the MERG waveform may be due to slowed temporal adaptation in the aged retina.