Model 01 · Retinal Imaging
Automated AMD severity grading from colour fundus photographs, with classification aligned to established clinical grading systems.
Clinical Background
Age-related macular degeneration (AMD) is the leading cause of irreversible central vision loss in individuals over 50 in high-income countries. It affects approximately 196 million people worldwide, with this number projected to rise substantially as populations age.
The macula, located at the centre of the retina, is responsible for high-acuity central vision — essential for reading, face recognition, and fine motor tasks. AMD causes progressive degeneration of the photoreceptors and retinal pigment epithelium (RPE) in this region.
Early-stage AMD is asymptomatic or produces only subtle visual changes that patients may not notice or attribute to ageing. By the time significant symptoms emerge, irreversible structural damage has typically occurred. Early detection allows initiation of lifestyle interventions, nutritional supplementation (AREDS2 formula), and close monitoring that can meaningfully delay progression to advanced disease.
Colour fundus photography provides a direct view of the retinal surface. AMD hallmarks — drusen (yellow-white deposits beneath the RPE), pigmentary abnormalities, geographic atrophy, and choroidal neovascularisation — are directly visible and amenable to automated image analysis.
| Level | Classification | Key Features |
|---|---|---|
| 0 | No Macular Degeneration | Normal foveal reflex. Absent or minimal small drusen (<63 µm). No RPE abnormalities. No neovascularisation. |
| 1 | Mild Macular Degeneration | Medium drusen (63–124 µm) without RPE abnormality, or small drusen with pigmentary changes. No geographic atrophy in the central subfield. No late AMD features. |
Technical Specification
Clinical Pathway
The AMD model outputs a severity level and confidence score. In the EyeMap deployment workflow, results are presented as a screening report to the optometrist, not directly to the patient. The report includes an explicit statement that findings require clinical confirmation.
Any result at Level 1 (Mild AMD) or above, or a Level 0 result with confidence below a defined threshold, triggers a recommendation for ophthalmologist referral. The referral decision remains with the qualified optometrist or clinician reviewing the report.
In the UK Biobank validation study, we will examine AMD classification change over time to assess the model's utility in detecting early progression — a clinically meaningful capability that static grading alone cannot provide.