Visual Acuity & Refractive Converter
Convert Snellen metric (6/6), Snellen Imperial (20/20), LogMAR, Decimal, and approximate dioptric refractive blur equivalent.
SRK-T Biometry Formula
Cataract Intraocular Lens (IOL) Power Estimator
Estimate implant lens power based on axial eye length, corneal curvature (K1, K2), and lens A-constant for clear post-operative spectacle independence.
Interactive Clinical Assessment
Enter clinical parameters below for immediate computerized evaluation. Results update instantaneously.
Average adult eye axial length is 23.50 mm (Range 22.0 – 25.0 mm).
Standard average corneal power is 43.50 – 44.00 D.
Consultant Clinical Insight
"High-precision ophthalmic diagnostics and proactive screening prevent over 80% of preventable visual impairment. Early detection gives patients the greatest opportunity for spectacle freedom and retinal preservation."
Dr. Praveen Kumar
Consultant Cataract & Refractive Surgeon · Dr. Anil Kumar's Eye Hospital
Clinical Background & Evidence Base
Intraocular lens power (P) is calculated through optical biometry using the classic SRK formula P = A - 2.5*(AL) - 0.9*(K_avg), where A is the manufacturer lens constant (typically 118.4 for modern hydrophobic acrylic lenses), AL is axial length in millimeters, and K_avg is the mean corneal keratometry in diopters. Customized toric and multifocal algorithms incorporate anterior chamber depth (ACD).
Clinical Staging Reference
| Classification / Stage | Clinical Interpretation & Care Pathway |
|---|---|
| Standard Myopic / Normal Eye (AL 22.0 – 24.5 mm) | Typical IOL power ranges between +18.0D and +23.0D. Excellent predictability with monofocal, toric, and extended depth of focus (EDOF) lenses. |
| Hyperopic / Short Eye (AL < 22.0 mm) | Requires higher power IOL (+24.0D to +30.0D). Crowded anterior segment; careful evaluation of angle closure glaucoma risk prior to phacoemulsification. |
| High Myopic / Long Eye (AL > 25.0 mm) | Requires lower or negative power IOL (+6.0D to +16.0D). Pre-operative indirect ophthalmoscopy mandatory to screen for peripheral retinal tears and lattice degeneration. |