MST instruments ease IOL explantation — transforming complexity, ensuring simplicity
This first article in the Complex Cases, Simplified series features a case study by Dr Nicole Fram, M.D., in which three MicroSurgical Technology [MST] instruments are used: Packer/Chang IOL Cutters, Hoffman/Ahmed Micro-Scissors, and Micro-Holding Forceps. These small and powerful micro instruments ease the explantation of an IOL, making the whole procedure more manageable for the surgeon and more comfortable for the patient.
The Case of a 62-year-old Female with Negative and Positive Dysphotopsia
Nicole Fram, MD. Advanced Vision Care (Los Angeles, CA, USA)
IOL Exchange Strategy — One year after a toric IOL implantation, the patient needed an IOL exchange due to negative and positive dysphotopsia. A recent study conducted by Bonnie Henderson MD[1], and colleagues found that positioning the optic-haptic junction of an acrylic IOL inferotemporally resulted in a 2.3-fold decrease in the incidence of negative dysphotopsia after cataract surgery. When dealing with persistent negative dysphotopsia in our practice, our primary therapeutic strategy is to elevate the optic on top of the anterior capsule placing it in reverse or anterior optic capture. However, the patient also complained of persistent positive dysphotopisa. In these cases, my approach is to exchange the lens material for a lower refractive index such as silicone or collamer. Unfortunately, there are no fully rounded edge IOLs available for exchange to alleviate positive dysphotopsia.
Explantation Procedure — Firstly, I used the Donnenfeld Femto Spatula to get under the anterior capsule. I then use a dispersive ophthalmic viscoelastic device (OVD) to help free the anterior capsule from the IOL. Some prefer a cohesive in this circumstance. It is helpful to place viscoelastic down the optic-haptic junction where there can be significant adhesions in a single piece acrylic (SPA) IOL. It’s as if the OVD is another instrument in the eye. When dissecting the haptics out of the bag one should gently lift up rather than rotate as the latter could tear the zonule. Resistance is different depending on the type of SPA IOL. For example, the Acrysof platform haptics typically has the most fibrosis at the terminal bulbs of the haptic, whereas the Tecnis platform will have resistance at the haptic optic junction. Understanding when to amputate, rather than destroying the zonule, is key to successful IOL explantations.
Sometimes using the 23g MST Micro-Holding Forceps for countertraction in one hand and a spatula for dissection in the other hand allow you to get the lens out of the bag much easier. I used the 19g MST Packer/Chang Cutters, to bisect the lens once it is in the AC and progress to remove it through a 2.2–3.0 mm incision. The MST Micro-Holding Forceps is designed specifically to hold IOLs while you cut them with the Packer/Chang IOL cutters. The MST forceps are serrated to firmly grasp any foldable IOL during explantation. The jaws of the forceps open wide enough to capture even the thickest IOL.[2] These features are what makes the instruments so valuable in simplifying complex cases.
When dissecting the lens out of the bag with the MST Packer/Chang Cutters, it’s important to have enough OVD pushing the posterior capsule back and to pull towards yourself as you are cutting to avoid cutting capsule or iris. After the lens removal, I wanted to ensure the equator remains open if I want to implant another lens.
Finally, and without difficulty I inserted a new IOL material to address the positive dysphotopsia, and I elevated the optic on the top of the capsule to address the negative dysphotopsia. First, I put the lens into the bag and then I use the bimanual approach under the lens to get all the viscoelastic out. Afterwards, I lift the lens with a spatula and grab the optic with the MST forceps and then elevated the optic in front of the nasal and temporal capsule, achieving reverse optic capture. It is imperative to get coverage of the nasal capsule with the optic. If the capsulotomy is too big then one can place the IOL in the sulcus.
When Haptic Amputation is Needed — When dealing with dysphotopsia from a multifocal IOL placed years prior, it can be difficult to get the haptic out of the capsular bag. The MST 23g Hoffman/Ahmed Scissors can easily amputate the haptic with its strong blades and whilst the MST forceps grab it. The optic of the lens can then be cut and explanted with the Packer/Chang Cutters and the MST forceps. Using the bimanual technique helps to ease a potentially challenging amputation. The added control of a bimanual technique to cut an IOL optic is very safe because trauma to the iris or capsule can be avoided more easily.[3] The short, powerful scissor blades mean that much smaller cuts can be made, reducing the risk of accidentally cutting the capsule or iris compared to the larger cutting motions required when using traditional IOL scissors with longer blades. [3]
When the lens optic is out, the removal of the remaining haptic is much simpler thanks to the MST serrated forceps providing great control and precision. The MST forceps allows me to move freely intraoperatively, therefore easing complex IOL explantation.
In conclusion, this case was simplified by both the MST scissors and forceps. This is mainly due to the design and high quality of the MST instruments. They allowed me to take a challenging case and transform it into a manageable procedure.
Key learnings
· In patients with persistent negative dysphotopsia, our primary therapeutic approach is to perform a reverse optic capture.
· The literature is clear that the leading cause of positive dysphotopsia is square-edge IOL[4] and reflectivity of the IOL. Unfortunately, there are no fully round edge IOLs. Therefore, my primary strategy in positive dysphotopsia persisting for more than 3–6 months is exchange of the lens material.
· MST Packer/Chang IOL Cutters, Hoffman/Ahmed Scissors and Micro-Holding Forceps allow Surgeons control and room to move in procedures of a difficult or small spaced nature.
· Lens Exchange — The Packer/Chang Cuters are well suited for IOL cutting as they carry minimal risk of collateral damage to the capsule, iris or endothelium. The fine tips, controlled opening, sharpness and precision of the scissors allows the IOL to be cut cleanly with minimal pressure, thereby reducing the risk of torsion so there is no lens twisting. They cut very cleanly to divide the lens in a controlled manner, making lens exchanges a lot easier.[5]
References
1. Henderson BA, Yi DH, Constantine JB, Geneva II. New preventative approach for negative dysphotopsia. J Cataract Refract Surg 2016;42:10:1449–1455.
2. Microsurgical.com https://microsurgical.com/product/20/
3. Charters , L. IOL cutter small size, strength boons to IOL explantation procedure. Sep 15, 2008. Available at: https://www.changcataract.com/pdfs/iol_cutter_small_size_strength_boons_to_iol_explantation_procedure.pdf
4. Stephenson, M. Dysphotopsia: Not Just Black and White. Review of Ophthalmology. Nov 7, 2017. Available at: https://www.reviewofophthalmology.com/article/dysphotopsia-not-just-black-and-white
5. Little, B. The value of micro instrumentation in successful surgery. Ophthalmology Times. Oct 1, 2015. Available at: https://www.ophthalmologytimes.com/ote-articles/value-microinstrumentation-successful-surgery
