Improved refractive outcomes
EyeSuite IOL provides excellent IOL calculation and enables improved outcomes for spheric-, toric- and multifocal-IOL with any patient.
Efficient planning - intuitive transfer to surgery
EyeSuite IOL offers latest generation IOL calculations such as Barrett and Olsen for standard IOL, enabling improved results with any patient. It further includes a comprehensive set of premium post-refractive formulae, including Barret’s True-K and the Masket formula which are regarded as best in class. For torics it optionally offers a complete planning suite to calculate the implant, considering the front and back of the cornea and create intuitive surgery sketches, enabling excellent transfer of the plan to surgery.
Stay on target any time
Standard IOL calculations provide good results in average eyes; they fail in short and long eyes as well as eyes with special anatomic features. EyeSuite IOL features the Barrett and Olsen formula, enabling excellent refractive results with any patient anatomy.
Lens thickness - improved results
Standard formulae use axial length and K measurements to calculate IOL power, limiting their performance with unusual eyes. Barrett and Olsen use more parameters, including anterior chamber depth and lens thickness to estimate implant power. This improves the prediction of the implant position and enables better results, independent of the patient anatomy.
Prediction of the implant position is the proverbial Achilles Heel of any standard IOL calculation formula. Hoffer Q, SRK/T and Holladay 1 calculate the ELP based on axial length measurement and K reading and assume that a long eye leads to deeper anterior chamber as well as steep K and vice versa. Many studies on eye anatomy have shown that short eyes often have fairly standard anterior chamber depths; this explains why these formulae tend to misestimate IOL power in non-average eyes.
Barrett and Olsen use more directly related parameters to calculate the implant position. The most important parameters in this respect are anterior chamber depth (ACD) and lens thickness (LT). Modern IOLs are implanted in the capsular bag of the crystalline lens and therefore ACD and LT are directly related to the implant position post-operatively.
Barrett Universal II - a formula for all seasons
Unlike most standard formulae, the Universal II formula is a thick lens formula, taking into account the changes in optics design of IOLs at different powers. In addition to AL and Ks, it uses ACD, lens thickness and WtW measurement to predict the lens position and IOL power, leading to excellent refractive outcomes in all patients.
The lens factor (LF) used to calculate the implant position is similar to the A-constant, surgeon factor, or C-constant of other formulae. However the Universal II formula recognized that this component of the estimated lens position (ELP) is also influenced by anatomic factors such as AL, K, ACD, lens thickness (LT), and white-to-white. In a recent retrospective study on pooled data of more than 5’900 eyes, it was shown that the Barrett Universal II formula performed significantly better than the standard formulae Haigis, Hoffer Q, Holladay 1 and SRK/T in average, short (AL ≤ 22.5mm) and long (AL ≥ 25.5mm) eyes. On the pooled data, Unversal II achieved 81% of the eyes within 0.5 D of the intended refractive result.
Olsen - the C-constant a new concept
The Olsen formula uses ray tracing, a method well known from optics design, to calculate lens power and the concept of the C-constant to predict implant location. As an input parameter, apart from AL and Ks, Olsen uses ACD and LT measurement enabling excellent implant position prediction in all eyes.
The advantage of the C-constant is that it is directly associated with the relevant anatomy of the anterior segment and not dependent on the k readings or other factors. Therefore, the C-constant works in short and long eyes and would even work in other species if an IOL is implanted in the capsular bag using similar technique.
In a clinical series on more than 1700 eyes, Dr. Olsen assessed the performance of the Olsen formula as compared to standard formulae like Holladay 1 and SRK/T. All measurements were taken with Lenstar and independently of the eye length, the Olsen formula using the concept of the C-constant and paraxial and exact ray-tracing outperformed the standard formulae.
The right tools for post refractive patients
IOL calculation in post refractive patients is one of the most demanding tasks in cataract surgery. To support the surgeon with this challenge, EyeSuite IOL features a comprehensive set of cutting-edge formulas for post refractive patients with or without clinical history.
Best in class formulae for premium results
IOL power calculation in patients with prior RK, LASIK or PRK, presenting with no history, is easily achieved with the integrated Barrett True-K and Shammas No-History method. If the change in refraction caused by the refractive procedure is known, then the Barrett True-K with history, Masket and modified Masket formulae may also be used.
The challenge with post refractive corneas is that the Gullstrand ratio of the anterior to the posterior corneal curvature is no longer given. This leads to two main issues. Firstly, the K-readings are reported too flat with the cornea after an intervention to correct myopia and too steep for a prior hyperopic patient. Secondly, in standard calculation formulae, the lens position is calculated based on AL and K-readings. Since the Ks no longer represent the initial cornea, the lens position calculation is wrong as well. Post-refractive formulae overcome both issues by correcting either the formula or the result for the issues mentioned.
Match axis and cylinder
Getting the cylinder value and axis location right is key with toric IOL. The optional EyeSuite IOL Toric Planner features the Barrett Toric Calculator for excellent IOL prediction and an intuitive graphical planning interface to create sketches to transfer the plan to surgery.
Excellent calculation, intuitive planning
The EyeSuite IOL Toric Planner provides the user with an intuitive tool to plan the toric intervention on high resolution eye images. Using the incision optimization tool enables the surgeon to put his incision in the exact right location to achieve the minimum anticipated residual astigmatism, with the lowest toric power IOL implanted.