Detecting early eye changes in diabetic children using Optical Coherence Tomography Angiography (OCTA)

Both Diabetes Mellitus (DM) and healthy participants will be required to attend annual visits at the Lions Eye Institute for 5 years (inclusive of enrolment visit). Visits will be approximately 3 hours in duration. During these visits visual and imaging assessments as described below will be performed by study staff: Ocular history and changes to ocular signs/symptoms – takes about 5 minutes Relevant ocular history will be recorded. After the first visit, any changes to ocular history since the previous visit will be recorded. Demographics – takes about 2 minutes Date of birth and sex will be recorded at Visit 1. Use of ACE inhibitor or ARB medications We will record use of specific medications called ACE (angiotensin converting enzyme) inhibitors or ARBs (angiotensin receptor blockers). If the child is diabetic, information will be requested from the Western Australian Children’s Diabetes Database. Height and Weight- takes about 3 minutes height and weight will be measured. Blood Pressure- takes about 7 minutes blood pressure will be measured once. The child will be asked to sit down on a chair and rest for 5 minutes before the reading is taken Visual Acuity- takes about 20 minutes Visual Acuity will be checked by assessing ability to see letters of different sizes on a chart at a distance. Measurement of Intraocular (eye) pressure - takes about 2 minutes The intraocular pressure of the eyes will be checked. A small instrument lightly touches the front of the eye to measure pressure. Pupil dilation Standard of care eye drops will be used to dilate the pupils. Visual function test: this will take about 5 minutes Participants are shown a series of patterns on a provided iPad that contain either 1, 2 or 3, black (OFF) or white (ON) squares that are superimposed on a textured background. The participant needs to indicate the number of squares that are present, by selecting a push button on the tablet screen. This will continue for 2 mins per eye. Optical Coherence Tomography (OCT) – this will take about 10 minutes The participant will position themselves on a chair with their chin on a chin rest and look into the device. This device takes scans which are used to assess the health of the back of the eye (the retina). Optical Coherence Tomography Angiography (OCTA) – this will take about 50 minutes This device takes scans which allow the research doctor to collect information about the blood vessels in the retina of your child’s eyes. Images will be taken on two devices. One is the current clinical standard, the other is a specially designed OCTA device for research. Colour Fundus photography – this will take about 30 minutes The participant will position themselves on a chair with their chin on a chin rest and look into the device. This camera takes a picture of the back of the eye (fundus). It is taken on two machines, one is a “normal view” and the other is an “ultra wide view”. Dilated Ophthalmic examination – take about 5 minutes Examination of the structures in the front, middle and back parts of the eyes. To examine the back of the eye they will be dilated (as described above) and a magnifying instrument will be used to see into the back of the eye. Blood and urine tests – kidney function 5 mL of blood and a urine sample will be collected at each visit to assess markers related to kidney function. Additional Blood sample – general markers An additional 10mL of your blood will be collected at each visit to assess general markers such as the amount of glucose in the blood, lipid profile and full blood count. If the patient is diabetic and has had these blood tests done within the last 3 months of their visit at the PCH clinic, we will not collect this additional blood sample and use these results instead. A novel method of quantifying retinal perfusion is being investigated by calculating the Coefficient of Variation measure (CV). The CV method using OCTA to estimate retinal perfusion is non-invasive as it does not require injection of any tracer/contrast element and requires no specific or specialised equipment or tools. A standard commercial OCTA machine is used so the experience is identical to having a normal OCTA scan which is very well tolerated, the patient is asked to fixate on a light and a scan is completed within seconds. The primary difference for this CV method being that instead of a single OCTA scan we take repeated OCTA scans over several minutes of the same eye and calculate intensity differences between each blood vessel on these repeated scans to estimate retinal perfusion variability represented as a CV value. This retinal perfusion is hypothesised to be compromised in pathologic states and there is no discomfort at all for patients having these repeated OCTA scans. The specific methodology for this is described in our recent publication (Yu, DY., Mehnert, A., Balaratnasingam, C. et al. An assessment of microvascular hemodynamics in human macula. Sci Rep 13, 7550 (2023). https://doi.org/10.1038/s41598-023-33490-8)