Development and evaluation of thin-film flexible microelectrode arrays for retinal stimulation and recording.

We have described the development of a flexible microelectrode array with potential applications in the large scale recording of neural signals and in focal electrical stimulation for use as a prosthetic implant in degenerative retinal diseases. The array under test consisted of 61 platinum electrodes of 5 µm diameter with 60 µm spacing connected by 8 µm wide gold tracks encased in a flexible polyimide substrate of 15 µm thickness from which recordings were taken from 16 electrodes. The device was tested on an exposed frog eyecup preparation which is characterized by small retinal ganglion cells of similar dimensions to those present in the human retina. The responses of these cells evoked by photic stimulation consisted of trains of action potentials of high signal-to noise ratio at each of the recording sites. Delivery of cathodal constant voltage pulses and constant current pulses to specific electrodes in the array led to the generation of action potentials in adjacent electrodes, implying that retinal ganglion cells in the proximity had been stimulated. Since prolonged stimulation with supra-threshold voltages impaired neither electrode structure nor retinal function, these results provide a sound basis for scaling up the number of array electrodes to deliver focal electrical pulses to the retina, as would be required by a viable epiretinal prosthesis.

Psychological support for patients undergoing breast cancer surgery: a randomised study.

OBJECTIVE: To evaluate the effect of support from a nurse specialising in breast care and a voluntary support organisation on prevalence of psychological morbidity after surgery for breast cancer. DESIGN: Prospective randomised study. SETTING: Three teaching hospitals in Glasgow with established breast clinics. SUBJECTS: 272 women aged less than 70 years undergoing surgery for breast cancer. INTERVENTIONS: Patients were randomly allocated to receive routine care from ward staff, routine care plus support from breast care nurse, routine care plus support from voluntary organisation, or routine care plus support from nurse and organisation. MAIN OUTCOME MEASURES: Prevalence of psychological morbidity as assessed by self rating scales: 28 item general health questionnaire and its subscales, and hospital anxiety and depression scale. Measurements were made at first postoperative clinic visit and at three, six, and 12 months after surgery. RESULTS: On each self rating scale, psychological morbidity tended to fall over the 12 month period. For each scale, scores were consistently lower in patients offered support from breast care nurse alone compared with the other groups, which were similar to each other. Differences were significant or nearly so: P values were 0.015 (28 item general health questionnaire), 0.027 (anxiety and insomnia), 0.072 (severe depression), 0.053 (somatic symptoms), 0.031 (social dysfunction), 0.093 (hospital anxiety), and 0.003 (hospital depression). CONCLUSION: Support from breast care nurse can significantly reduce psychological morbidity, as measured by self rating scales, in women undergoing breast cancer surgery.