Haag-Streit Lenstar Optical Biometer
While the introduction of optical biometry revolutionized cataract surgery in the late 1990s, Haag-Streit is writing the latest chapter in biometry history with its Lenstar LS 900. The Lenstar provides highly accurate laser optic measurements for every section of the eye − from the cornea to the retina − and is the first optical biometer on the market that can measure the thickness of the crystalline lens.
With its integrated Olsen formula and the optional Toric Planner featuring the Barrett Toric Calculator, the Lenstar provides the user with latest technology in IOL prediction for any patient. Dual zone keratometry, with 32 measurement locations or topography measurement with the optional T-Cone, provides reliable and precise mea-surements for the K values, axis, and astigmatism that are essential to the sophisticated planning of toric lenses.
The Lenstar LS 900 offers the optimal planning platform for superior refractive outcomes in cataract surgery, both now and in the future.
Topography for torics – match the axis
With the optional T-Cone toric platform, the axis and astigmatism measurement of Lenstar is extended with true 11-ring Placido topography. This additional data improves the efficacy and safety of toric IOL surgery, eliminating the risk of irregularities and allowing the user to double check the axis location on the topography maps as well as in the surgical planning sketch on high resolution images of the patient’s eye. The T-Cone is combined with the EyeSuite IOL Toric Planner for optimal planning of the intervention based on the Barrett Toric Calculator.
DUAL ZONE KERATOMETRY OR T-CONE TOPOGRAPHY
Precise measurements and intuitive
planning – best toric results
Lenstar’s unique dual zone keratometry provides measurement of the axisand astigmatism, equivalent to the "Gold Standard" manual keratometry2,3 recommended for toric IOL by manufacturers. The closely spaced 32 measurement point pattern improves precision, both delivering more data and minimizing the need for software data interpolation. Optionally, the Lenstar can be equipped with the T-Cone topography add-on. That feature not only enables axis and astigmatism measurement but also offers full topography maps of the central 6 mm optical zone. In addition to topography, EyeSuite IOL also now features a toric IOL planning platform that is included with the T-Cone.
QUICK AND RELIABLE BIOMETRY FOR ALL EYES
Fast, precise and comprehensive for better refractive results. The measurement process of the Lenstar is fast and optimized to ensure maximum patient comfort – users report five scans of both eyes in three minutes or less, optional the Automated Positioning System (APS) features dynamic eye-tracking allowing easy automated measurement acquisition with a single click. The Dens Cataract Measurement (DCM) Mode ensures state-of-the-art cataract penetration. Each of the measurements can be validated for efficacy and adjusted, if necessary, to ensure complete bi-ometry accuracy. In addition to the Olsen, Barrett and standard IOL calculation formulae Eye-Suite IOL provides the user with a set of premium IOL calculation formulae for post-keratorefractive patients. Barrett True-K, Shammas No-History, and Masket formulae have proven their efficacy in several peer-reviewed studies and may be regarded as best-in-class
Central corneal thickness (CCT)
As for every other Lenstar axial measurement, optical coherence biometry is used to measure CCT with stunning reproducibility of ±2 μm. CCT is a key parameter in glaucoma diagnosis, and is also used for laser refractive surgery and/or to differentiate prior myopic or hyperopic LASIK procedures when there is no patient history.
Keratometry K / TopographyTopo
Lenstar’s unique dual zone keratometry, featuring 32 marker points, provides perfect spherical equivalent7, magnitude of astigmatism and axis position2,3, making it the biometer of choice for toric IOL's. With the optional T-Cone topography add-on, Lenstar provides full topography maps of the central 6 mm optical zone that are crucial for cataract planning.
Based on high-resolution color photography of the eye, every white-to-white measurement can be reviewed and adjusted by the user if necessary. As such, it is fully reliable for use with anterior chamber and sulcus-fixated pha-kic IOLs. It can also be used to determine advanced IOL calculation formulae.
Measurement of the pupil diameter in ambient light conditions can be used as an indicator for the patient’s suitability for apodized premium IOLs, as well as for laser refractive procedures.
Lens thickness LT
Accurate measurement of the lens thickness is key to optimal IOL prediction accuracy when using the latest IOL calculation formulae, Olsen or Holladay 2. Measuring the lens thickness with Lenstar significantly improves the IOL prediction accuracy of Holladay 2 and leads to a different IOL power selection in 30% of cases4.
Anterior chamber depth ACD
Like all axial dimensions captured by the Lenstar, ACD is measured by optical coherence biometry, providing more precision and reproducibility 7. This allows ACD to be measured on phakic as well as on pseudophakic eyes8. Additionally, the Lenstar is able to display the anatomical anterior chamber depth (endothelium to anterior lens surface).
Axial length AL
OLCR technology, using a superluminescent diode as the laser source, enables measurement of the axial length of the patient’s eye, precisely on the patient’s visual axis and in the presence of dense media.
The user can review and move all of the measuring gate positions on the A-scan if necessary.
The Lenstar A-scan appears very similar to an immersion ultrasound scan, for easy user interpretation. The advanced digital signal processing used with the Dens Cataract Measurement (DCM) mode provides cutting-edge performance with respect to penetration rates.
Special eye conditions
All of the described measurements are available for use on the regular eye, as well as for aphakic, pseudoaphakic and silicone oil-filled eyes. In case of error, users may even change the selected eye condition after completion of the measurement procedure.
A new approach for IOL power selection
The Hill-RBF Method is a purely data driven IOL calculation technique incor-porating pattern recognition based in artificial intelligence and sophisticated data interpolation. It features a boundary model for improved accuracy and confidence. RBF stands for Radial Basis activation Function a method used in mathematical modeling. The Hill-RBF Method performs as good in short and long eyes. Used on short eyes, it clearly outperforms Holladay and Hoffer Q and shows slightly better results than latest theoretical formula. The elemental advantage is achieved through the process of adaptive, dy-namic learning. Unlike static theoretical formulae, the Hill-RBF Method is an ongoing project and is continuously updating for an even better overall depth of accuracy.
Get the IOL position right – every time
Estimating the postoperative IOL position is the key aim, but also the pro-verbial Achilles heel, of any IOL calculation formula. With its unique con-cept of the C-Constant, the Olsen formula calculates the postoperative lens position as a fraction of the crystalline lens thickness and the ACD. This approach allows accurate calculation of the lens position independent of the corneal status of the eye. The lens position is then used to calculate the IOL power based on ray tracing, the same technology used to design telescopes and camera lenses.
Barrett True-K, Shammas No-History and Masket – for premium results
The Lenstar EyeSuite software provides the user with a comprehensive set of cutting-edge IOL calculation formulae for normal eyes. IOL Power calculation in patients with prior RK, LASIK or PRK, presenting with no history, is easily achieved with the on-board Barrett True-K and Shammas No-History method. If the change in refraction is known, then the Barrett True-K with history, Masket and modified Masket formulae may also be used.