Movement-Artefact-Free Measurement of T 1 in the Human Eye to Determine Oxygenation of the Vitreous Humour

Background: Eye measurements are complicated by eye movement since subjects frequently find the need to blink [1]; suppression of blinking beyond about 3 s can be painful. Although eye drops could be used, these must be administered by skilled personnel. We demonstrate a method for rapid imaging of eye movement and have developed an imaging technique that reduces this movement and permits the measurement of T1 without image artefact. Poor oxygenation of the vitreous humour leads to retinopathy and, in patients with low oxygenation (pO2) at the retina, a vitrectomy may be performed, where the vitreous humour is extracted and replaced by saline. However, there is no clear evidence that an increase in vitreous pO2 is actually achieved by this procedure and a MRI measurement of pO2 would provide an important validation for ophthalmologists. Accurate and precise measurement of T1 could provide such a non-invasive determination of eye oxygenation since T1 times are subtly increased by reduced pO2. In pure water at 1.5T and 37 oC T1=4.74s [2], and T1 decreases by 47 ms (1.14 %) for an increase in pO2 of 10 mmHg (calculated from ref [3]).