Eye Calculators and Tools for Ophthalmologists
Last updated: November 2026
Every calculator and quick tool on RPC Rounds in one place. The Calculator pages work in your browser: type the numbers and the answer updates at once. The Reference pages hold tables, formulas and links to trusted online calculators.
Refraction and optics
Refraction calculatorsSpherical equivalent, anisometropia, retinoscopy, near add, AC/A, prismCalculatorTransposition and vertex toolTranspose a prescription and convert it to the corneal planeCalculatorVisual acuity converterSnellen, logMAR, decimal and near equivalentsCalculatorVertex distanceFormula and worked examplesReferencePrentice's ruleInduced prism with worked examplesReferenceSpectacle dispensingPD, fitting height and tolerancesReferenceFormulas in ophthalmologyThe exam formulas on one pageReference
Contact lenses
Contact lens calculatorSoft spherical, soft toric, RGP base curve and tear lens, K converterCalculatorContact lens quick referenceVertex table, LARS, RGP and keratoconus fittingReference
Cataract and IOL
SRK II calculatorTry SRK II, and compare SRK/T, Hoffer Q and Holladay 1CalculatorOnline IOL calculatorsBarrett, Kane, Hill-RBF and other trusted toolsReferenceIOL power after refractive surgeryWhich method to use, step by stepReferenceIOL A-constantsConstants by brand and modelReferenceBiometry checklistWhen to recheck, which formulaReferenceLRI calculatorLimbal relaxing incision nomograms and online toolReference
Low vision and certification
Low vision aids calculatorKestenbaum rule and magnificationCalculatorVisual disability certificatePercentage under the RPwD Act (India)CalculatorVision standards for driving and jobsIndian requirements at a glanceReference
Strabismus, drugs and research
Strabismus measurement and surgical dosesPrism conversions and dose tablesReferenceIntravitreal drug dosagesDoses and preparationReferenceFortified dropsHow to prepare fortified antibiotic dropsReferenceDiagnostic test calculatorSensitivity, specificity, PPV and NPV from a 2 × 2 tableCalculator
For patients
These tools are for learning and quick checks. Confirm any result that changes treatment with your own measurement, the manufacturer's guide or a validated device.
See also: Clinic desk reference, Normal values in ophthalmology, Made Easy series.
📘 Want more exam-ready material? See Most Commons in Ophthalmology on Kindle, or browse all my books.
Looking for an eye specialist in Ahmedabad? Learn about our Eye Department or book a consultation with Dr. Dhaval Patel.