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Biomedical subjects

C O'Brien

Publications and source records attributed to C O'Brien.

At least 91 records · Page 5Linked to original sources
PubMed1997

Long-term results and complications after trabeculectomy with a single per-operative application of 5-fluorouracil.

We retrospectively evaluated a consecutive series of 45 patients (45 eyes) who underwent trabeculectomy augmented with a single intra-operative 5 minute application of 5-fluorouracil (5-FU; 25 mg/ml). All patients were at an increased risk of subconjunctival fibrosis and surgical failure. The mean follow-up period was 24 months (range 12-42, SD 6.9). The mean pre-operative intraocular pressure (IOP) was 29.1 mmHg (SD 6.1) and the mean IOP at the last post-operative visit was 16.6 mmHg (SD 6.4) (p < 0.0001) with a mean IOP reduction of 42%. The number of medications reduced from a mean of 2.3 (SD 0.7) pre-operatively, to 0.8 (SD 0.7) post-operatively (p < 0.0001) and 22 eyes (49%) required no topical treatment for IOP control. An IOP of 21 mmHg or less with or without medications was achieved in 80% of cases. There was no significant difference in final IOP or success rate over time between low- and high-risk patients, although the low-risk patients did better in the first 12-18 months. Complications included hypotony maculopathy in 2 cases (4%), leaking bleb in 5 cases (11%) and giant bleb in 1 case (2%), giving a total of 8 cases (18%) with bleb-related sequelae. In the short to medium term, a single per-operative application of 5-FU is a useful adjunctive treatment during glaucoma filtering surgery for low- to moderate-risk cases, although a steady increase in the failure rate was associated with increasing length of follow-up.

Adult↗
PubMed1997

Psychosocial factors and prediction of headaches in college adults.

The current study evaluated psychosocial variables that may contribute to the experience of headache in college adults. One hundred ninety-nine participants, 103 women and 96 men, completed head pain logs for 4 weeks after completing measures assessing psychosocial variables. Multiple regression analyses indicated that level of emotional functioning, perception of stress, and gender were predictive of future headache frequency, intensity, and duration. Family history and health habits did not predict headache activity. These findings are consistent with research investigating psychosocial variables and headache activity.

Adult↗
PubMed1997

Pulsatile ocular blood flow in untreated diabetic retinopathy.

PURPOSE: To measure the pulsatile component of total ocular blood flow in patients with untreated diabetic retinopathy. SUBJECTS AND METHODS: An adapted pneumotonometer attached to a slit-lamp biomicroscope. 82 age-matched subjects divided into 4 groups: non-diabetic controls (n = 22); diabetics with no clinical retinopathy (n = 20); background diabetic retinopathy (n = 20); pre-proliferative/proliferative diabetic retinopathy (n = 20). RESULTS: The mean pulsatile ocular blood flow values were found to be increased in all grades of diabetic retinopathy (no retinopathy 818 microl/min, background 1015 microl/min, pre-proliferative/proliferative 1097 microl/min) compared to the control group (644 microl/min). These pulsatile ocular blood flow values were significantly higher (p<0.05) in the background and pre-proliferative/proliferative retinopathy groups compared to controls. Pulse volume and pulse amplitude were also higher in the diabetic subjects. Mean arterial blood pressure did not differ across the groups studied. CONCLUSION: Pulsatile ocular blood flow was found to be higher in diabetics compared to controls and appears to increase as the severity of retinopathy progresses. Such a hyperdynamic circulation may contribute to the pathogenesis of diabetic eye disease.

Aged↗
PubMed1997

Effect of chronic inhibition of nitric oxide synthase on ocular blood flow and glucose metabolism in the rat.

AIMS: To investigate the effects of chronic administration of nitric oxide synthase inhibition on ocular blood flow and metabolic demand in the rat and to compare these effects with changes in the cerebral and peripheral circulation. METHODS: Male Sprague-Dawley rats were injected with the nitric oxide synthase inhibitor L-NAME (75 mg/kg i.p.), either on a single occasion only or once daily for 10 consecutive days. Controls were injected with saline. Regional blood flow and glucose metabolism were measured from tissue samples, using [14C]-iodoantipyrine and [14C]-2-deoxyglucose respectively, 1 hour after either acute L-NAME injection or 1 hour after the last injection of the chronic treatment protocol. RESULTS: Mean arterial pressure was significantly increased (+31%) following the acute injection (indicating peripheral vasoconstriction) and this effect was enhanced (+50%) following chronic treatment. In both the ocular and cerebral circulation, blood flow was decreased following acute treatment (-48% and -43% respectively). However, while this response was totally attenuated in the cerebral circulation following chronic L-NAME treatment (-4%), the ocular circulation remained responsive (-57%). Metabolic demand in brain and eye tissue, as reflected in the accumulation of 2-deoxyglucose, was unaffected by either acute or chronic treatment with L-NAME. CONCLUSION: Homeostatic mechanisms appear to be activated in the cerebral circulation which re-establish flow metabolism homeostasis, and the effect of L-NAME on cerebral blood flow is attenuated following repeated exposure. This process does not seem to happen in the ocular circulation and, thus, the ocular vasculature appears to behave more like those blood vessels which determine total peripheral resistance than the cerebral circulation. It remains to be seen whether the sustained decrease in blood flow in the eye is sufficient to compromise ocular function and render the eye susceptible to damage from chronic L-NAME induced oligaemia.

Animals↗
PubMed1997

Color Doppler imaging in untreated high- and normal-pressure open-angle glaucoma.

PURPOSE: To evaluate ocular blood flow velocity indices in untreated primary open-angle glaucoma (POAG) and normal pressure glaucoma (NPG). METHODS: Twenty-five untreated patients with NPG, 23 untreated patients with POAG, and 26 age-matched normal control subjects underwent color Doppler imaging for the measurement of blood flow velocity in the central retinal and ophthalmic arteries. Neither the patients nor the control subjects were using systemic beta-blockers or calcium channel blockers. After log transformation of non-normal data, group differences were compared with a one-way analysis of variance followed by unpaired t-test with the Bonferroni correction. Statistical significance was set at P < 0.05. RESULTS: The central retinal artery end diastolic velocity was significantly lower in patients with POAG than in normal subjects. The ophthalmic artery peak systolic velocity (PSV) was significantly greater in patients with POAG than in those with NPG and normal subjects. The resistance index (RI) of both the ophthalmic and central retinal arteries was significantly greater in patients with POAG than in normal subjects, and the central retinal artery RI was significantly greater in those with NPG than in normal subjects. Systemic pulse pressure and systolic blood pressure were significantly greater in patients with POAG compared with normal subjects. Multiple regression analysis showed a significant relation between ophthalmic artery PSV and intraocular pressure (but not with any of the cardiovascular parameters) in the POAG group. Chi-square analysis found significantly more systemic vascular disease in patients with NPG and POAG compared with that of normal subjects. CONCLUSIONS: There was an increased resistance to blood flow in the central retinal artery of untreated patients with NPG and POAG and also in the ophthalmic artery of patients with POAG. The ophthalmic artery peak systolic velocity was elevated in untreated patients with POAG. Altered ocular circulation (with different patterns of presentation) appears to be common to patients with NPG and patients with POAG.

Aged↗
PubMed1997

Results of two levels of adjunctive treatment used with the nicotine patch.

The authors compared 9-, 16-, 26-, and 52-week outcomes for two randomly assigned groups of nicotine-dependent subjects: 1) nicotine patch plus four smoking cessation sessions with a nurse-practitioner giving advice and instruction (n = 36; moderate-intensity condition, MI); or 2) the foregoing treatments plus 16 weekly individual cognitive/ behavioral relapse-prevention therapy sessions (n = 33; high-intensity condition, HI). Patch completion rates were 69.7% in the HI group and 55.6% in the MI group (NS). Self-reported abstinence rates at the four follow-up points were comparable for the two treatment groups; HI: 39%, 36%, 36%, and 36%; MI: 44%, 28%, 25%, and 28%, respectively. There was some indication that MI patients with high nicotine dependence had lower abstinence rates than highly dependent HI patients.

Administration, Cutaneous↗
PubMed1997

The diagnostic outcome of new glaucoma referrals.

A retrospective cohort study of the case notes of 295 patients referred to the glaucoma clinic at the Royal Infirmary of Edinburgh between October 1993 and March 1994 was performed. The purpose of the study was to determine the diagnostic outcome of new referrals suspected of having glaucoma, all of whom were examined by a single glaucoma specialist. The largest diagnostic group was ocular hypertension (113, 42%), just over half of which were started on treatment. A new diagnosis of glaucoma was confirmed in 46 patients (17%). In total, 107 patients (39%), required treatment (46 glaucoma and 61 ocular hypertension). Thirty-six percent of new referrals were either discharged (80, 29%) or had other ocular conditions unrelated to glaucoma (19, 7%). A proportionately high number of new glaucoma cases (15 out of 46) had normal intraocular pressures, which emphasises the important role of ophthalmoscopy and perimetry in case detection. In conclusion, the number of newly diagnosed cases of glaucoma (17%) is considerably less than previous reports (22-39%), with a high proportion of referrals (2 in every 5) having ocular hypertension.

Adult↗
PubMed1997

Accuracy of referral to a glaucoma clinic.

The accuracy of referral to the glaucoma clinic in Edinburgh was evaluated retrospectively by case note analysis. Two hundred and ninety-five patients suspected of having glaucoma were referred during a 6 month period. Optometrists accounted for 96% of referrals with the remainder being referred directly by the GP. The highest overall detection rates (glaucoma + glaucoma suspects) were amongst those optometrists who combined tonometry with either a field assessment, ophthalmoscopy or both (66-78%). Despite this there was a high false positive rate with 36% of referrals being discharged or having conditions unrelated to glaucoma. To improve referral efficiency it is recommended that optometrists should routinely combine tonometry with ophthalmoscopy and perimetry, and tests should preferably be repeated prior to referral if an abnormality is suspected. The accuracy of referrals could be improved by the use of Goldmann applanation tonometry and by better interpretation of perimetric findings.

Aged↗