Biomedical subjects

Ian Andrew Cunliffe

Publications and source records attributed to Ian Andrew Cunliffe.

3 recordsLinked to original sources

PubMed2006

Objective accommodative amplitude and dynamics with the 1CU accommodative intraocular lens.

PURPOSE: To compare the objective accommodative amplitude and dynamics of eyes implanted with the one-compartment-unit (1CU; HumanOptics AG, Erlangen, Germany) accommodative intraocular lenses (IOLs) with that measured subjectively. METHODS: Twenty eyes with a 1CU accommodative IOL implanted were refracted and distance and near acuity measured with a logMAR (logarithm of the minimum angle of resolution) chart. The objective accommodative stimulus-response curve for static targets between 0.17 and 4.00 D accommodative demand was measured with the SRW-5000 (Shin-Nippon Commerce Inc., Tokyo, Japan) and PowerRefractor (PlusOptiX, Nürnberg, Germany) autorefractors. Continuous objective recording of dynamic accommodation was measured with the SRW-5000, with the subject viewing a target moving from 0 to 2.50 D at 0.3 Hz through a Badal lens system. Wavefront aberrometry measures (Zywave; Bausch & Lomb, Rochester, NY) were made through undilated pupils. Subjective amplitude of accommodation was measured with the RAF (Royal Air Force accommodation and vergence measurement) rule. RESULTS: Four months after implantation best-corrected acuity was -0.01 +/- 0.16 logMAR at distance and 0.60 +/- 0.09 logMAR at near. Objectively, the static amplitude of accommodation was 0.72 +/- 0.38 D. The average dynamic amplitude of accommodation was 0.71 +/- 0.47 D, with a lag behind the target of 0.50 +/- 0.48 seconds. Aberrometry showed a decrease in power of the lens-eye combination from the center to the periphery in all subjects (on average, -0.38 +/- 0.28 D/mm). Subjective amplitude of accommodation was 2.24 +/- 0.42 D. Two years after 1CU implantation, refractive error and distance visual acuity remained relatively stable, but near visual acuity, and the subjective and objective amplitudes of accommodation decreased. CONCLUSIONS: The objective accommodating effects of the 1CU lens appear to be limited, although patients are able to track a moving target. Subjective and objective accommodation was reduced at the 2-year follow-up. The greater subjective amplitude of accommodation is likely to result from the eye's depth of focus of and the aspheric nature of the IOL.

Accommodation, Ocular↗

PubMed2005

Systemic reduction in glutathione levels occurs in patients with primary open-angle glaucoma.

PURPOSE: To assess the level of plasma glutathione in patients with untreated primary open-angle glaucoma. METHODS: Twenty-one patients with newly diagnosed primary open-angle glaucoma and 34 age- and gender-matched control subjects were subjected to a blood analysis to detect the level of circulating glutathione in its reduced and oxidized forms. The effect of age, gender, and systemic blood pressure on circulating glutathione levels was also analyzed. RESULTS: Age had a negative effect on the level of both reduced and total glutathione (P = 0.002, r = -0.52 and P = 0.002, r = -0.52, respectively) in control subjects but not in patients with glaucoma (P > 0.05, r = 0.27, and P > 0.05, r = 0.22, respectively). In the control group, men demonstrated higher levels of both reduced and total glutathione than did women (P = 0.024 and P = 0.032, respectively). After correction for age and gender influences on blood glutathione levels, patients with glaucoma exhibited significantly lower levels of reduced and total glutathione than did control subjects (P = 0.010, F = 7.24 and P = 0.006, F = 8.38, respectively). No differences between study groups were observed in either oxidized glutathione levels or redox index (P > 0.05, F = 0.50; and P > 0.05, F = 0.30, respectively). CONCLUSIONS: Patients with glaucoma exhibit low levels of circulating glutathione, suggesting a general compromise of the antioxidative defense.

Age Factors↗

PubMed2004

Abnormal systemic and ocular vascular response to temperature provocation in primary open-angle glaucoma patients: a case for autonomic failure?

PURPOSE: To assess systemic and ocular vascular reactivity in response to warm and cold provocation in untreated patients with primary open-angle glaucoma and normal control subjects. METHODS: Twenty-four patients with primary open-angle glaucoma and 22 normal control subjects were subjected to a modified cold pressor test involving immersion of the right hand in 40 degrees C warm water followed by 4 degrees C cold water exposure, and finger and ocular blood flow were assessed by means of peripheral laser Doppler flowmetry and retinal flowmetry, respectively. Finger and body temperature as well as intraocular pressure, systemic blood pressure, systemic pulse pressure, heart rate, and ocular perfusion pressure were also monitored. RESULTS: The patients with glaucoma demonstrated an increase in diastolic blood pressure (P = 0.023), heart rate (P = 0.010), and mean ocular perfusion pressure (P = 0.039) during immersion of the tested hand in 40 degrees C water. During cold provocation, the patients demonstrated a significant decrease in finger (P = 0.0003) and ocular blood flow (the parameter velocity measured at the temporal neuroretinal rim area; P = 0.021). Normal subjects did not demonstrate any blood flow or finger temperature changes during immersion of the tested hand in 40 degrees C water (P > 0.05); however, they exhibited increases in systolic blood pressure (P = 0.034) and pulse pressure (P = 0.0009) and a decrease in finger blood flow (P = 0.0001) during cold provocation. In normal subjects, the ocular blood flow was unchanged during high- and low-temperature challenge. CONCLUSIONS: Cold provocation elicits a different blood pressure, and ocular blood flow response in patients with primary open-angle glaucoma compared with control subjects. These findings suggest a systemic autonomic failure and ocular vascular dysregulation in POAG patients.

Aged↗