Toric Set II
Toric Set III
Toric Set IV
DOUG MASTEL WRITES:
Toric intraocular lenses have changed cataract surgery significantly since their introduction decades ago. As with all surgical procedures, many nuances are involved.
First, you must have accurate measurements that are in concordance across diagnostic devices. After ruling out irregular astigmatism or significant non-orthogonal topographies, these IOL’s can achieve very good visual outcomes. However, industry and many ophthalmic leaders have oversimplified the accuracy and precision necessary to achieve consistent results while avoiding to the best of one’s ability the ‘refractive surprises, which is currently a hot topic. Our goal is to assist you in accurate placement of Toric lenses, hopefully within a degree or two of the surgical plan vectoring.
Mastel has over 35 years of surgical astigmatism instrumentation design and applications experience. Two things are required in all astigmatic corrections:
1.) Pre-Operative Marking with the patient sitting up that can be identified once the patient is supine for surgery to identify cyclotorsion.
2.) Intra-Operative Marking for placement of phaco incisions and IOL orientation along the steep/flat meridians.
Pre-Operative Marking~Various premarkers allow for inkless application (if desired) due to veryfinely sharpened and polished marking edges unique to Mastel workmanship. By applying these markers with firm pressure for about 5 seconds, the surgeon will be able to find the marks up to half an hour later by simply drying the epithelium to reveal their positioning.
Ink may certainly be added but in our experience it often bleeds to the point of being inaccurate or else simply washes away and disappears at the time of need. The most common (70% of surgeons in the USA)
apply dots on the sclera at 3 and 9 o’clock [0/180] or 3, 6 and 9 2 [0/180/270] locations. This can readily be shown to be inconsistent or inaccurate leading to errors of 5-10 degrees. We have seen cyclotorsion up to 25 degrees on a few patients, 5-10 degrees can be commonplace. Modern methods employing wave front
aberrometry or heads up displays have high tech appeal to today’s ophthalmic surgeon. This fact remains to be true; the simplicity of accurate and reliable premarks will always be an identifiable orientation, either as a primary or back up surgical solution, during astigmatism correction surgery. Redundancy provides safety factors
that Robert Osher, MD terms ‘Belt and Suspenders Thinking’.
Intra-Operative Marking~During the procedure, the surgeon must either juxtaposition his/her preoperative marks (commonly placed at 3 and 9 o’clock positions at the limbus or 3, 6 and 9) by applying a Mendez form of ring. Designs mimic the foropter refraction patterns from 0 to 180 and then repeating for the other half of the circle to identify the steep meridian with a meridian marker.
It is critical to have accurate placement of the ring in reference to the preoperative marks. Many legacy Mendez Rings are very large to the point they must be held above the cornea and do not fixate the eye as do our Gimbel-Mendez designs which do fit within the palpebral fissures. It is quite easy to make a 5-10 degree mismarking error if the premarks are inaccurate for whatever reason. If one considers the inherent difficulties of marking to begin with, both prior to surgery and during the surgery, it is clear that errors of 20 degrees or more could occur at
While one cannot control the postoperative effective lens position perfectly due to healing or inherent surgical inaccuracies, accurate placement is something that should be controlled as well as possible yet
1.) Centering on the Visual Axis during both premarking and surgery are key. Our system considers alignment first of the surgeon to patient eye axis; second is centration of the IOL relative to this line of sight and third; orientation of the astigmatism procedure to the steep meridian. This is best accomplished by using our Zero Parallax Visual Axis Glasses with premarking applications and with our intraoperative Lindstrom-Stegmann –Hardten
Illuminating Surgical Keratoscope (ISK or ring light). Both feature a most helpful blinking red fixation light (Jones SteadyPulse)
2.) Accurate premarking~preferaby sans ink with various markers based upon personal preference
3.) Accurate intraoperative alignment tied to the premarking approach that guarantees as well as possible precision to the degree necessary today to minimize human error in an arguably
important form of medical art.
We hope this is of assistance to you in your instrument selection process.