Accuracy supports eye surgery
For more than 15 years, optical biometry has been the key examination prior to any cataract surgery. Indeed, the ocular biometry examination is an essential step to the pre-surgery report as it makes possible measuring some eye important dimensions to calculate the power of the intraocular lens (IOL) that will replace the crystalline lens.
To calculate the implant power, we use formulas that require essential and precise biometric measures of the eye, particularly the axial length (AL) and the central keratometry (measure of the cornea radius of curvature). Previously, measuring the axial length was performed using the ultrasound method. Now, the optical biometry makes possible saving mainly the indications of ultrasound biometry to the densest cataracts.
The optical biometer NIDEK AL-Scan integrates formulas to calculate the implant power. The purpose of a precise calculation of power is providing an implant whose post-surgery refractive result will match each patient’s specific needs and wishes.
Our solutions in optical biometry
The optical biometer AL-Scan uses several technologies at the same time:
- The Partial Coherence Interferometry (PCI),
- The Scheimflug camera to analyse the cornea and the anterior chamber depth,
- The integrated ultrasound mode (optional) for white cataracts.
The axial length of the eye is optically measured using Partial Coherence Interferometry (PCI) technology. The device measures the time required, using an infrared light, to go to the retina. A partially coherent infrared light source is emitted to the eye, where it is subjected to different reflexions. An analyser detects the returning emerging signal formed inside the eye. The interferences formed by the addition of the signals are then used to calculate the distance between the different eye structures that collected the light. This technology is used to perform a contactless measure of the eye axial length while bringing many benefits: rapidity, accuracy and user’s friendliness.
The optical biometer AL-Scan is equipped with a Scheimflug camera to acquire a section image of the anterior segment and get the value of the cornea thickness and the value of the anterior chamber depth.
The ultrasound measure of the axial length (optional mode) is required in case of dense cataracts. The measuring principle follows the Mode-A ultrasound scanning biometry principle. The time required by the sound to go from the cornea to the retina is measured. The sound travel time is then converted into a distance (axial distance in millimetres).
Benefits of optical biometry
Auto-tracking 3D et déclenchement automatique pour gagner en précision et reproductibilité
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The Art of Eye Care
NIDEK develops its top-of-the-range products to improve visual health through an approach based on strict criteria: safety, reliability, durability, continuous quality controls and certifications.
NIDEK meets technical challenges by keeping constantly informed of the innovations of eye imaging systems, using the expertise of professionals and the progresses of research.
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