Patients with glaucoma and related eye diseases could soon be treated with a refillable drug delivery device, replacing the need for injections into the eyeball. Ellis Meng and colleagues at the University of Southern California, Los Angeles, US, have made a simple polymer device that attaches to the eye and delivers drugs to the site of disease via a flexible tube inserted into the side of the eye.

'This work came out of discussions with a retinal surgeon,' says Meng. 'He has days where patients line up to have injections into their eye because there's a lack of good drug delivery mechanisms for diseases that lead to blindness.'

The team showed their device, which is about one centimetre long, could be refilled repeatedly by piercing it using a syringe needle, without it developing a leak. Once attached to the eye, pressing the drug reservoir dispenses the treatment through the delivery tube into the relevant part of the eye. Similar tubes are already used to drain excess fluid from the eyes of glaucoma patients, Meng adds.

Susan Barker studies drug delivery devices for the eye at the University of East Anglia, Norwich, UK, and agrees that the device would be less invasive than current alternatives. 'This looks quite nice - the drug is effectively delivered into the side of the eye rather than an injection from the front. But manually dispensing the drug might not give a consistent dose and the device is quite large. Would the patient be able to feel it?'

Meng says she plans to address these issues. 'This prototype isn't optimally sized; it's our first go at proving the concept,' she explains. 'We're now building a next-generation device, which won't have square corners but will be rounded and contoured.' The next device will also be powered by a simple electrolysis pump to deliver accurate doses of the drug.

James Mitchell Crow