Ophthalmology Calculators
16 calculators & risk scores
Browse 16 Ophthalmology clinical calculators and risk scores used in everyday UK practice. Every tool runs entirely in your browser — enter the values and get instant scoring, colour-coded interpretation bands and a link to the underlying guideline or publication. ClinCalc Pro is free, needs no sign-up, and is built for working clinicians.
These ophthalmology tools span Visual Acuity, Diabetic Retinopathy, Macular Degeneration, Glaucoma, Dry Eye / Sjögren's, Ocular Trauma and more.
- LogMAR ⇄ Snellen Visual Acuity ConverterMaps distance visual acuity (Snellen line, better eye) to its LogMAR value and the WHO ICD-11 distance visual-impairment category (WHO uses presenting acuity; UK certification uses corrected acuity and the visual field). LogMAR = log₁₀(1 / decimal acuity); each step on a standardised ETDRS chart is 0.10 log units (5 letters). Counting fingers and hand movements have conventional values (≈1.9 and ≈2.3); light perception (2.7) and no light perception (3.0) are imputed, not measured.
- ICDR — International Clinical Diabetic Retinopathy Severity ScaleGlobally adopted clinical classification of diabetic retinopathy (Wilkinson 2003, AAO 2017). Drives screening interval and laser/anti-VEGF decisions. Combine with diabetic macular oedema (DMO) staging.
- AREDS Classification of Age-related Macular DegenerationAge-Related Eye Disease Study (AREDS) clinical categories 1–4 (AREDS Report 8, 2001). Stratify the 5-year risk of progression to advanced AMD and guide AREDS2 supplementation.
- Intraocular Pressure Stratification & Glaucoma RiskCategorises Goldmann applanation IOP against the NICE NG81 referral and treatment threshold (24 mmHg) and the College of Optometrists' urgency thresholds (over 35 mmHg urgent, 40 mmHg or more emergency). Thin corneas tend to under-read; central corneal thickness is weighed as a separate risk factor (NICE NG81).
- Schirmer Test Severity for Dry Eye DiseaseQuantifies aqueous tear production (Schirmer I — without anaesthesia). Strip placed at junction of middle and lateral 1/3 of lower lid, eyes closed for 5 minutes. Severity levels follow the DEWS 2007 grading (≤10, ≤5, ≤2 mm). Wetting of 5 mm or less in at least one eye scores 1 point in the 2016 ACR/EULAR primary Sjögren's classification criteria (4 or more points classify).
- Roper-Hall Classification of Chemical Ocular BurnsOriginal classification of chemical (alkali/acid) eye injuries (Roper-Hall 1965), based on corneal involvement and limbal ischaemia. Predicts visual prognosis and guides referral urgency. The Dua classification (2001) is a more granular modern alternative.
- Dua Classification of Chemical Ocular InjuriesModern 6-grade classification (Dua 2001) using analogue clock-hour limbal involvement and percentage conjunctival involvement. More granular than Roper-Hall, with better prognostic accuracy.
- Hertel Exophthalmometry — Proptosis AssessmentHertel exophthalmometry measures axial globe position from the lateral orbital rim to the corneal apex. Normal values vary with race and sex; a side-to-side difference of 2 mm or more is abnormal. Used in thyroid eye disease, orbital tumour, cellulitis and post-trauma evaluation.
- Diabetic Macular Oedema (DMO) ClassificationDiabetic macular oedema (DMO) classified on examination / OCT as absent, non-centre-involving or centre-involving (ICO 2017), with centre-involving DMO split by visual acuity (DRCR Protocol V). Drives observation, anti-VEGF and laser decisions.
- Traumatic Hyphaema GradingGraded by % of anterior chamber filled with blood after blunt trauma. Higher grade predicts secondary haemorrhage (rebleed at 2–5 days), elevated IOP, and corneal blood-staining.
- HAP Glaucoma Staging (Hodapp-Anderson-Parrish)HAP (Hodapp-Anderson-Parrish) classification stages glaucoma severity into Early, Moderate or Severe using visual-field mean deviation (MD) on 24-2 SITA-Standard fields. Used to stratify follow-up and treatment intensity.
- Retinopathy of Prematurity — International Classification (ICROP3)International Classification of Retinopathy of Prematurity 3rd revision (Chiang 2021). Combines Zone (I most posterior, III peripheral nasal), Stage (1–5), and Plus disease; Type 1 (treat) and Type 2 (observe) ROP are the ETROP definitions (2003). Used to time treatment in screened preterm neonates.
- Hirschberg & Krimsky Test — Strabismus Angle EstimationBedside estimation of ocular deviation when prism cover test is impractical (uncooperative child, dense amblyopia). Hirschberg: corneal light reflex displacement from pupil centre; each 1 mm ≈ 7° (≈15 prism dioptres / 15Δ), so with a 4 mm pupil the pupil margin ≈ 15°, mid-iris ≈ 30° and limbus ≈ 45°. Krimsky modifies by adding prisms over fixing eye until reflex is centred.
- Primary Angle Closure Disease Spectrum (PACS / PAC / PACG)ISGEO consensus continuum of primary angle closure disease (Foster 2002, EAGLE 2016). Distinguishes occludable angles (PACS) from those with PAS or elevated IOP (PAC) and from established glaucomatous neuropathy (PACG). Critical for laser-iridotomy and lens-extraction decisions.
- Central Corneal Thickness Correction for Goldmann IOPCentral corneal thickness (CCT) affects Goldmann applanation readings, but published correction formulae disagree and none improves glaucoma risk prediction (OHTS). CCT is recorded and used as a risk factor alongside IOP.
- Refractive Error & Myopia Severity ClassificationInternational Myopia Institute classification (IMI 2019): myopia is a spherical equivalent (SE) of −0.50 D or less, high myopia −6.00 D or less, using cycloplegic refraction in children. Pathologic myopia is defined by structural changes, not by refraction. Higher myopia confers greater lifetime risk of myopic maculopathy, retinal detachment, glaucoma, and cataract.