Colour Fundus Photography

What it does

Colour Fundus Photography reads the screening exam of ophthalmology: one or two 45° fields per eye, ultra-widefield images, or photos from handheld and smartphone cameras. Each image is checked for gradability first; an image too dark, blurred or obscured by cataract or a small pupil is reported as ungradable with retake advice, not graded.

Gradable images get the full read per eye: an ICDR diabetic retinopathy grade with referable and vision-threatening flags and lesion masks, a CFP-surrogate maculopathy grade, vertical cup-to-disc ratio and referable-glaucoma likelihood, AREDS simplified severity for AMD, artery and vein calibres with a hypertensive retinopathy grade, a papilloedema check and a screen for other referable disease. The per-eye grades roll up into a patient-level referral urgency mapped to the screening programme's rules, for example NHS DESP R0–R3, M0–M1 and U.

Intended use

Decision support for diabetic eye screening and primary eye care, where photographs are taken by technicians and read by graders, GPs, diabetologists, optometrists and residents. The result gives a consistent grade with the lesions that justify it and a referral urgency. Fundus photos show macular oedema through surrogate signs, exudates within one disc diameter of the fovea, which set the M1 maculopathy grade; Retinal OCT measures the oedema itself.

Who it is for

Screening programmes and their graders, optometrists, diabetologists, GPs, emergency physicians looking for papilloedema, and ophthalmology residents. Developers call the run from camera software and telemedicine platforms to add structured grading to screening workflows.

Accepted input

• DICOM: Ophthalmic Photography 8/16-bit and Wide Field Ophthalmic Photography objects.
• Image files: JPEG, PNG or TIFF exports from fundus cameras, as most screening programmes export them, plus handheld and smartphone images under a stricter quality gate.
• One study is both eyes of one visit, with one or more images per eye.

Requirements

Requirement	Why
Laterality (ImageLaterality) or detectable laterality	Grades are per eye (OD/OS); a classifier fills the gap
Macula-centred field	DR grading and maculopathy around the fovea
Disc-centred field	Cup-to-disc ratio, papilloedema
Pixel spacing or field-of-view angle	Cup-to-disc ratio, vessel calibres in µm and lesion areas
Both eyes	AREDS simplified severity is a patient-level score

Optional context

Known diagnoses (diabetes, hypertension, glaucoma, AMD), age and sex, and the screening programme whose referral rules apply go in clinical_context.

The result

Section	Content
Image quality	Good, usable or reject per image, field definition, artefacts, retake advice
Diabetic retinopathy	ICDR grade 0–4 per eye, referable and vision-threatening DR, surrogate maculopathy (M0/M1), gradability, heat maps
Retinopathy lesions	Microaneurysm, haemorrhage, hard exudate and cotton-wool spot masks with counts
Glaucoma (optic disc)	Disc and cup masks, vertical cup-to-disc ratio, rim and RNFL-defect features, referable-glaucoma likelihood
Age-related macular degeneration	Drusen size, pigmentary abnormalities, late AMD, AREDS simplified score 0–5 and 5-year risk
Retinal vessels	Artery/vein masks, CRAE, CRVE, AV ratio, tortuosity, fractal dimension, hypertensive retinopathy grade
Papilloedema	Papilloedema versus normal or pseudo-papilloedema, Frisén grade, urgent neuro-imaging prompt
Other referable findings	Vein occlusion, pathologic myopia, retinal detachment, optic atrophy, macular hole and similar findings
Retinal anatomy	Optic disc, cup, fovea and artery/vein masks with their measurements
Retinal age and cardiovascular risk	Retinal age gap and cardiovascular risk estimated from the fundus photo
Draft report	Opt-in (options.report): an English narrative that interprets the result for the reader (findings, impression, limitations); every number is checked against the findings

Standards

• DICOM: SEG for lesions, vessels, disc and cup; SR TID 1500 with TID 2120 and TID 2127 ophthalmic measurement groups; KOS key images and Encapsulated PDF.
• Diabetic eye disease: International Clinical DR and DME severity scales (AAO, Wilkinson 2003) and NHS DESP grading (R0–R3, M0–M1, U).
• Glaucoma: vertical cup-to-disc ratio and the ISNT rule.
• AMD: AREDS Simplified Severity Scale and the Beckman clinical classification (2013).
• Vessels and neuro-ophthalmology: Knudtson CRAE/CRVE, Wong–Mitchell and Keith-Wagener-Barker grades, Frisén scale.
• Coding: SNOMED CT and ICD-10/ICD-11 with explicit laterality (OD/OS/OU).