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  Zeiss IOLMaster®
Online Users Instruction Manual V.5
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IOL Power Calculations IOL Power Calculations
Optical Biometry Optical Biometry
Lens Constants Lens Constants
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Zeiss IOLMaster® Zeiss IOLMaster
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IOLMaster — Overview.

Intended Use

  IOL Master IOLMaster

The IOL Master is to be used only for the measurement of axial length, corneal radii, 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 IOLMaster other than as intended lies with the user.

The IOL Master may only be used in combination with accessories delivered by Carl Zeiss Meditec. Please consult Carl Zeiss Service regarding the use of other accessories.

Package Contents

The IOLMaster is delivered in completely assembled form, packed in foam material.

The enclosed accessory box contains the following components:

Save the original packaging for storing the IOLMaster during extended periods of non-use or for returning it to Carl Zeiss Meditec, or dispose of it properly.

Functional Description

The IOLMaster is a combined biometry device for measurements on the human eye required for the 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 formula 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 IOLMaster, 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 IOLMaster.

The control program for the computer in the IOLMaster base runs under Windows. A backlit LCD serves to observe the patient's eye and display the readings. The IOL Master is controlled by the joystick and computer keyboard with integrated touch-pad.

Based on the readings, the program can make suggestions for the choice of intraocular lens strengths. The latter are based on internationally accepted calculation formulas. The Haigis, HofferQ, Holladay, SRK II and SRK/T formulas are implemented in the software.1

The Haigis-L formula may be used to calculate IOL's following myopic LASIK/PRK.1

The refractive history or contact lens method may be used to correct the measured corneal radii/refraction following refractive corneal surgery.1

Selected phakic lens implants may be calculated with the Phakic IOL tab.1

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 formulas may be optimized (personalized) for each individual user.


Literature on the formula (for specific questions contact Carl Zeiss Meditec):

  • Haigis: http://ocusoft.de/ulib/
  • HofferQ: HOFFER KJ: The Hoffer Q formula: A comparison of theoretic and regression formulas. J Cataract Refract Surg, 19:700-712, 1993; ERRATA 20:677, 1994
  • Holladay: HOLLADAY JT, PRAGER TC, CHANDLER TY, MUSGROVE KH, LEWIS JW, RUIZ RS: A three-part system for refining intraocular lens power calculations. J Cataract Refract Surg, 14:17-24, 1988
  • SRKII: RETZLAFF J: A new intraocular lens calculation formula, Am Intra-Ocular Implant Soc J 6:148-152, 1980
  • SRK/T: RETZLAFF J, SANDERS DR, KRAFF MC: Development of the SRK/T intraocular lens implant power calculation formula. J Cataract Refract Surg 16 (3):333-340, 1990
  • Haigis-L: HAIGIS W: publication in preparation
  • Correction of corneal radii/refraction after refractive corneal surgery:
  • HOLLADAY JT: IOL calculations following RK Refract Corneal Surg. 5(3):203, 1989 HOFFER KJ: Intraocular lens power calculation for eyes after refractive keratotomy. J Refract Surg. 11:490:493, 1995
  • Calculation of phakic implants:
    vd HEIJDE GL, FECHNER PU, WORST JGF: Optical consequences of implantation of a negative intraocular lens in myopic patients. Klin MB1 Augenheilk 192:99-102, 1988
    HOLLADAY JT: Refractive power calculations for intraocular lenses in the phakic eye. Am J Ophthalmol 116:63-66, 1993
    HAIGIS W: Biometry in complicated situations, 9th DGII Convention 1995, Rochels et al (publ.), Springer, 17-26, 1996

IOLMaster Help

Zeiss IOLMaster® Tutorial Version 5

Zeiss IOLMaster®

Optical Biometry

Intraocular Lens Power Calculations

East Valley Ophthalmology
5620 East Broadway Road
Mesa, Arizona 85206

Tel: +1-480-981-6111
FAX: +1-480-985-2426

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