Оптичен биометър Zeiss IOL Master V.5
Intended use of the device
The device is to be used only for the measurement of axial length, corneal radi, anterior chamber depth and optionally for the determination of “white-to-white” of the human eye, as well as for the calculation of the required intraocular lens. Responsibility for using the device other than as intended lies with the user.
Functional Description
The IOL Master is a combined biometry device for measurements on the human eye required for hte preoperative computation of intraocular lens power.
It is capable of fast and precise consecutive measurement of the following eye parameters in one session: axial length, corneal curvature, anterior chamber depth and optionally “white-to-white”. All measurements are non-contact, providing excellent patient comfort.
The axial length measurement is based on a patented interference optical method known as partial coherence interferometry (PCI). The displayed results of the axial length measurements are compatible with the ultrasonic immersion measurements of axial length via the use of an internal, statistically verified calculation algorithm. The familiar formulae for IOL calculation can thus be used.
However, the lens constants must be changed for use with the PCI method. Please consult the scientific literature on this subject.
The corneal curvature is determined by measuring the distance between reflected light images projected onto the cornea.
The anterior chamber depth is determined as the distance between the optical sections of the crystalline lens and the cornea produced by lateral slit illumination.
“White-to-white” is determined from the image of the iris.
The individual measurement procedures are automated, so that the operator is only required to adjust the device to the patient’s eye and initiate the measurement. For this reason the complex biometry of the eye can be rapidly learnt with the IOL Master, but should be practised with the greatest of care and attention to detail.
Extensive integrated safety features (independent redundant hard and software safety features) ensure maximum safety for both the patient and operator when using the IOL Master.
The control program for the computer in the device base runs under Windows. A backlit LCD serves to observe the patient’s eye and display the readings. The device is controlled by the joystick and computer keyboard with integrated touchpad.
Based on the readings, the program can make suggestions for the choice of intraocular lens strengths. The latter are based on internationally accepted calculation formulae. The Haigis, HofferQ, Holladay, SRK II and SRK/T formulae are implemented in the software.
The Haigis-L formula may be used to calculate IOLs after myopic LASIK/PRK.
The refractive history or contact lens method may be used correct the measured corneal radii/refraction following refractive corneal surgery.
Selected phakal implants may be calculated by the “calculation for phakic implants”.
An IOL database is likewise implemented. Prior to calculation, the latter must be filled with data for the desired lens.
On the basis of postoperative refraction results, the lens constants entered into the calculation formulae may be optimised (personalised) for each individual user.
