Premium IOL May be one way to achieve the visual goals of selected patients I describe some pearls for premium IOL implantation to help ensure that we hit the targeted refractive outcome and that patients are happy postoperatively

Premium IOLs are just like conventional IOLs, except that everything should be premium

Accuracy in IOL power calculations requires precise measurements, including axial length, lens thickness and keratometry, to provide the best estimate of the ELP by advanced formulas

Axial Length

Biomatry and AL Most important parts of the preoperative exam Prefer to use an optical biometer that measures ACD and lens thickness, in addition to axial length  improve the ELP prediction Optical biometry’s accuracy is within 0.01 mm, while with immersion it’s 0.1 mm 10 times more accurate

IOLMaster 700 SWEPT Source OCT technology into biometry to create the first SWEPT Source Biometry® device full-length OCT image showing anatomical details on a longitudinal cut through the entire eye >99% cataract penetration rate

Nidek AL-scan A new optical biometer which comes with the option of customization with a built-in ultrasound biometer and/or an ultrasound pachymeter It also has a signal booster and a signal-to-noise ratio enhancer, which allows it to measure axial length even in eyes with very dense cataracts It has a measurement range of 14mm to 40mm, compared to the 32mm limit of the Lenstar

Topcon Aladdin An optical biometer and topography instrument Of all its competitors it is the only one that includes a topographer It provides complete corneal topography, pupillometry, corneal spherical aberration and axial length measurements in a few seconds

Keratometry

Lenstar A total of five axial measurements (CCT, aqueous depth, anterior chamber depth, lens thickness, and axial length) by optical biometry Uses dual-zone keratometry, with two concentric rings of 1.65 and 2.30 mm

Lenstar The 16 measurement points in each ring comprise a total of 32 measurement points. Each displayed K reading is a composite of four measurements, representing 128 measurement points Performing five scans is recommended, which generates a total of 640 individual measurements per eye

Lenstar The greatest distance that any measurement can be from a principal meridian is only 11 degrees, the K readings are uniquely suited for toric IOL calculation

IOLMaster Comparatively, the IOLMaster measures only 3 points above and below the horizontal at 60 degrees,120 degrees, and 180 degrees Measures six points and uses those six points to mathematically compute a best-fit oval

Keratometry

keratometry Some will suggest using corneal topography for this purpose, since it measures hundreds or thousands of data points At what distance from the center do you measure the axis? Maybe the axis is at 20 degrees at 2 mm from the center, 18 degrees at 5 or 6 mm out and 12 degrees at 7 mm out? One way to proceed would be to use the points closest to the center, since that’s the part of the cornea  That’s a good premise, but then you’re basing the axis on a small number of data points again

Tomography

Tomography To measure corneal astigmatism and HOAs If HOAs exceed the safe level, the patient will experience more side effects with a multifocal lens than he or she would with a monofocal

Tomography Corneas with: HOA > 0.700 microns Spherical aberrations >0.400 microns Coma >0.300 microns are not good candidates for premium IOL surgery

Pentacam Effective Keratometry Reading (EKR) gives zonal keratometry values till 7 mm Corneas with wide distribution of K are not good candidates for premium IOL surgery

Orb scan Both Scheimpflug devices give little information about magnitude of irregularity beyond 3 mm Corneas with: >1.5 D irregularity in 3mm zone and >2.5D in 5 mm zone are better off without a premium IOL Angle kappas (> 0.4 mm or 2.8 degrees when using a penlight or >5.2 degrees on the Orbscan II, which measures about two times larger values) (are better off without a premium IOL)

Formula

A constant Personalized Lens Constant Never use Manufacturer’s Constant except to start 20 to 40 cases and continue Factors : IOL Style Lens placement Post op medications Biometer, keratometer, ...

Formula Use different IOL power calculation formulas depending on the characteristics of the eyes For eyes with normal AL SRK-T formula AL<22.5 mm Hoffer Q formula AL>26 mm Holladay or Haigis

Formula The popular 3rd generation formulas, the Hoffer Q, Holladay I and the SRK/T use two input variables, keratometry and AL, to try to predict ELP The 4th – and 5th generation formulas (the Holladay II, the Olsen formula and the Barrett Universal II formula) can use as many as seven variables (keratometry, AL, ACD, lens thickness, WTW, age and preop refraction in the case of the Holladay II, for example)

Formula Extensive testing has shown Holladay 2, Olsen, and Barrett Universal II to have the highest overall ±0.50 D outcomes accuracy For patients receiving a premium IOL, it may be best to consider using one of these three formulas

OCT–BASED INTRAOCULAR LENS POWER CALCULATION Directly measuring both ant&post corneal power  a higher predictive accuracy than regression- based formulas Because Fourier-domain OCT-based corneal power measurements were significantly lower than conventional keratometry, it is not appropriate to use these values in standard IOL formulas Therefore a different formula for OCT-based IOL calculation

Formulas on the Rise In addition to the fourth- and fifth- generation formulas, there are other formulas emerging as well, which should be making their way into general use SPECIALLY FOR PREMIUM IOLs

Hoffer H-5 Uses gender and race to change the average mean values in the Holladay-II and Hoffer Q formulas May be more customizable for a particular patient Is licensed to the IOLMaster 700

UniversIOL Calculator A web-based calculator that combines the major available lens formulas with a toric IOL calculator Bring together all the high-quality third- and fourth-generation IOL formulas in one calculator Also contains all the IOLs made so you can tell it which ones you work with

UniversIOL Calculator Also perform a toric calculation at the same time as the sphere Released for general use in May 2016

Radial basis function approach by fitting a large and highly accurate LenStar database to a sophisticated pattern recognition and data interpolation model called a radial basis function, which is based in artificial intelligence over 260,000 cases

Radial basis function approach Independent of vergence formulas, or a knowledge of the effective lens position Four variables—the desired spherical equivalent, AL, central corneal power and ACD—were all that was needed to accurately predict the necessary IOL power Will soon incorporate this into the LenStar

Ladas super formula 3-D computer model based on five popular IOL formulas: the Hoffer Q; Holladay I; Holladay I with Koch adjustment; Haigis and SRK/T

Super formula

Toric calculator The first toric calculators  used a constant multiplier of about 1.5 to compute the toricity needed in the IOL It varies, depending on the spherical equivalent power of the IOL, the K-readings and the distance of the IOL from the cornea

Toric calculator Suppose you’re dealing with a normal eye that has a 44-D cornea and a 22-D IOL at the normal depth you would indeed need a 3-D lens to correct 2 D of corneal astigmatism if you have a 34-D IOL, you’ll need about 2.4 D of correction to offset the 2 D of corneal astigmatism if you have a 10-D IOL, you’ll need 3.5 D of toric correction in the IOL

Toric calculator The IOL will also require more toricity if the cornea is steeper or if the lens is deeper in the eye Many calculators now take these factors into consideration, including the Holladay IOL Consultant, AMO’s toric calculator and (soon) Alcon’s next generation toric calculator and the Verion System

Summary Premium IOLs are an exciting area of interest to surgeons, our patients, and the ophthalmic industry New technologies help physicians to enhance outcomes with premium IOL patients It is not the IOL that is premium, it is the procedure that is premium