Verisyse or Artisan phakic IOL's are lens implants that are placed in the anterior chamber of the eye, attached to the iris, for correction of nearsightedness, or myopia. In the United States, the Verisyse is FDA approved from -5.0 D to -20.0 D of correction. There are 2 models of Verisyse with varying size of the lens portions, a 5 mm and a 6 mm optic lens. The 5mm Verisyse is approved for -5.0 D to -20.0 D whereas, the 6mm Verisyse is approved -5.0 D to -15.5 D. The current method of calculation for proper fit of the implant is using a calculator called the VeriCalc. Visante Anterior Segment OCT has a module that allows the proper calculation of these implants that is far more accurate and safer for the patient. In this page, I will present a case and how important Visante is in evaluating a patient. This is great opportunity to have a tutorial in proper use of the Visante for Verisyse.
42 year old female seeks refractive surgery.
OD -11.00 -2.75 x 021 --> 20/30
OS -9.75 -3.75 x 176 --> 20/25
OD 556 Microns
OS 550 Microns using DGH ultrasound pachymeter
The following are here corneal topographies done with the ATLAS 9000.
I prefer doing my topographies with the following configuration. I insist on seeing the ring images. I find the ring images help me tremendously to find pathology and also confirm the quality of the examination performed by my technicians. The one sees a very well done study showing a bow-tie astigmatism that is very symmetrical, with a normal mean curvature map.
Here the topography of the left eye is included to demonstrate the value of the ring images. One can see how the lashes are now interfering with the placido image and on the color map it is translated to a double blip on the superior bow-tie, and on the mean curvature map it creates an eccentricity. If one is unaware of these items by not looking at the ring images, there can be many false considerations.
A Visante omni is then performed showing the following maps.
The Holladay report here shows the imported anterior surface images from the ATLAS 9000 in the Anterior Curvature Map, The Anterior Elevation Map (Toric Ellipsoid) and the Anterior Mean Curvature Map. The Pachymetry Map is performed using the Global Pachymetry map that does 16 slices of the cornea at 10 mm each with 128 A-Scans. This translates into 2048 pachymetric data points. In the Relative Pachymetry Map, each of these 2048 spots are compared to the median thickness of the "normal" cornea. The percentage deviation is presented here. Therefore one can compare that to the what "should" be here. The Posterior Elevation (Toric Ellipsoid) Map is now the mathematically calculated fusion of the Anterior Elevation Map from the ATLAS data, and the Pachymetric Map from the Visante anterior segment OCT data. Here the map is very normal showing the highest point of elevation to be be a nominal 5.30 microns. So this map is essentially normal.
Here is the Holladay Report of the left eye. You can see how the lashes induced blip is also carried over. The report is also essentially normal.
Given her high myopia, iLASIK is not possible due to insufficient residual stromal bed. So a combined Verisyse implantation with IntraLase LASIK would give her the best option.
For the sake of ease only the right eye information will be presented here.
Initially she is considered for a -12.0 D 6mm Verisyse. Using the VeriCalc shows a 2.00mm endothelial clearance.
The patient had a Visante Anterior Segment examination and the Visante revealed a different result.
After the Enhanced Anterior Segment image was obtained the rainbow tool was activated. This tool provides a very quick easy way for seeing the clearance distance from the endothelium and also help guide the centeration of the Phakic IOL Tool. Then the Phakic IOL tool is activated and in this case a -12.0 D model 204 Artisan (6mm Verisyse) is chosen. I will clearly discuss how the Phakic IOL is to be placed later in the page, but you can easy see that even in absolute best case scenario, if the phakic IOL is perfectly placed (which is nearly an impossible act), the edges of the phakic IOL as less than the 1.5 mm clearance.
Well, we could change to a 5 mm Verisyse.
As you can clearly see the 5 mm Verisyse shown in the above case is far too small for this pupil size. The likelihood of glares and visual side effects increase in this case. As the patient needs to have her astigmatism corrected after the Verisyse implantation with LASIK surgery, why not use a lower power phakic IOL? The remaining refraction can be corrected using the excimer laser!
So lets try a -10.0 D Verisyse. The VeriCalc provided a 2.05 mm clearance!
The -10.0 D 6 mm Verisyse barely improved much above the -12.0 D 6mm model. Let's try a -7.0 D 6mm model. The VeriCalc provided a 2.12 mm endothelial clearance!!
As you can see, the 7.0 D 6mm Verisyse (Artisan model 204) fit well with small margin for error. I chose this lens for this patient. Now I will go through how each aspect of proper fitting is done on the Visante.
One of the other key aspects of proper fitting aside from the endothelial clearance is called "Crystalline Lens Rise." The CLR is measured using the Chamber tool.
In the above image, the chamber tool is placed and at the center the numbers above the crystalline lens show a 2.92 mm distance from the endothelium to the surface of the crystalline lens. The second number, 430 microns, is the crystalline lens rise or the CLR. A CLR of a 600 or more is a contraindication for doing a Verisyse implantation! A high CLR can cause "squeezing" of the iris again the Crystalline lens due to lens movements and accommodation and cause a pigmentary dispersion.
Dr. George Baikoff's article "Anterior segment OCT and phakic intraocular lenses: A perspective" published in the Journal of Cataract and Refractive Surgery, November, 2006, is a great resource and discusses the Crystalline Lens Rise in great detail. http://www.ncbi.nlm.nih.gov/pubmed/17081865
The key point to remember in doing a proper Chamber tool placement is discussed below.
As it can be seen in the above image, the angle tool is placed at the scleral spur. The scleral spur is defined on the Visante images as the point where the white sclera is separated from the grayer ciliary body. The chamber tool however is placed at the deepest portion of the angle.
In the above image once the model has been centered using the rainbow tool, the phakic IOL tool needs to be placed such that the foot plates are barely above the posterior pigmented iris line. Under this high magnification mode, it is much easier to also do the proper endothelial clearance tools (purple) which shows a 1.59 mm clearance (remember, the VeriCalc called out a 2.12 mm!!!). Additionally, the vault distance, which is the distance between the posterior side of the implant to the anterior surface of the crystalline lens is measured using the Vault Tool (orange). Here the vault tool measures the clearance to be 0.46 mm, which is an information not available using the VeriCalc.
So in the final model here, which took no more than 3 minutes to go through all the above exercise in total, you can see the phakic IOL model in yellow, the endothelial clearance tools in purple and the vault tools in the orange.
So the main question is how well does this compare to post operative results! Funny you should ask!
Here is the post-operative Visante Anterior Segment OCT of the right eye. Just as pre-operatively we had estimated 1.60 mm endothelial clearance, here we can see that it turned out to be 1.60 mm exactly!!!
The same image as the one before is now presented here with the Model 204 (6mm) Verisyse power of -7.0 D superimposed over the implant. There is nearly an identical match. The patient underwent an IntraLase, CustomVue with Iris Registration LASIK surgery (iLASIK) at 6 weeks after the second eye's Verisyse implantation. Given that the patient had the Verisyse, I was concerned about obtaining the CustomVue and the Iris Registration. However, they were easy to obtain! In the 2 images above the IntraLase flaps can be easily seen at the left side of the image just slightly to the right of the left endothelial marker.
I hope this case has presented to you the clear need for a precise tool like Visante in evaluation of patients for the Artisan or Verisyse Phakic IOLs.
The conventional methods simply using the VeriCal is simply not adequate. The calculator is grossly wrong in predicting the endothelial clearance and does not provide any information on the lens vault or the Crystalline Lens Rise. Additionally, Dr. George Baikoff elegant discussion of the Crystalline Lens Rise shows how it is essential in consideration for the Artisan / Verisyse lenses. The Visante Anterior Segment OCT provides all these metrics. Additionally, as demonstrated in this case, I was able to better serve and protect the patient by viewing multiple different implant options. The Visante allowed me to deliver a very predicable, precise result.
I am happy to hear from you and if there are any questions or concerns please feel free to contact me at DrAsh@ModestoEyeCenter.com.