Optical biometry is a non-contact method of measuring eye length and other parameters using light-based interferometry. It is a key step in calculating intraocular lens power for cataract and lens surgery.
Measurements
Devices measure axial length, corneal curvature, anterior chamber depth, and sometimes lens thickness and white-to-white distance. These values feed into formulae that predict the intraocular lens power needed for a desired refractive outcome.
- Provides highly repeatable axial length measurements
- Faster and more comfortable than ultrasound in most cases
- Accuracy can be affected by dense media opacities
- Data are stored for comparison and quality control
Clinical Role
Optical biometry has largely replaced A-scan ultrasound for routine cataract surgery planning. It also supports refractive lens exchange and monitoring of eye growth in myopia studies.
- Choice of biometry formula depends on eye length and anterior segment features
- Accurate keratometry values are essential for reliable results
- Special protocols exist for post-refractive surgery and unusual eyes
- Biometry data are integrated with clinical findings and patient goals
