EyeWorld Asia-Pacific March 2021 Issue

16 EWAP MAR C H 2021 FEATURE I ntraocular lens (IOL) fixation or exchange is generally required in IOL dislocation. In deciding the surgery required, I would consider the state of the capsular bag, type of IOL (single-piece, 3-piece, or plate), its material (hydrophobic or hydrophilic acrylic, silicone or PMMA), and the extent of dislocation. With a deficient posterior capsule but intact anterior capsule, the simplest solution would be an IOL exchange for a 3-piece IOL implanted in the sulcus with optic capture. An absent anterior capsule or excessively large capsulorhexis can also cause IOL dislocation and UGH syndrome. If the posterior capsule is intact, I would perform a posterior capsulorhexis and exchange for a 3-piece IOL with optic capture, or iris fixation with 10-0 prolene. Both methods prevent IOL movement and further irritation of the iris or ciliary body. Zonulysis is the most common cause of IOL dislocation. In eyes with no significant capsular fibrosis, I would reinflate the capsular bag with OVD using a cannula or a 27-G needle bevel down, starting at the optic-haptic junction. A capsular tension segment can then be placed in the bag and sutured to stabilize and center the complex. For those with extensive fibrosis, one option would be to lasso the haptics of an existing 3-piece IOL or capsular tension ring. Other methods would include using a 3-piece IOL with intrascleral tunnels or the Yamane technique. Recently, I have been more inclined to explant the entire IOL-capsular bag complex and scleral-fixate a MicroPure PhysIOL. The MicroPure is a hydrophobic acrylic IOL with four loop haptics which alleviates the risk of opacification associated with hydrophilic lenses. Firstly, 25-G pars plicata vitrectomy is performed with four ports 2.5 mm posterior to the limbus. The IOL-capsule complex is held with a micro- grasper and vitreous around the IOL is cleared to prevent traction. The IOL is cut and explanted using a “Pac-Man” technique. Two sutures are separately passed through the opposite haptics of the MicroPure IOL and the ends externalized through the existing ports with forceps. The IOL is then folded and implanted. The ports are removed and the sutures tied with the knots buried into the sclerotomies and the conjunctiva closed. I find this approach to be most consistent, and IOL centration can be easily titrated. My preferred suture is 7-0 Gore-Tex for its longevity compare to prolene, and I use dispersive OVD for all the above procedures. Editors’ note: Dr. Yeo is a consultant for Bausch + Lomb and Zeiss. a vitreoretinal colleague in to assist for the less experienced and combine surgery when the IOL is in the posterior vitreous cavity or on the macula,” she said. IOL removal considerations Karolinne Maia Rocha, MD, PhD, said there are several reasons an IOL may need to be exchanged. First, she noted significant residual refractive error. This might be a patient who cannot be corrected with refractive surgery. These are the patients who it’s clear on postop day 1 have the wrong power IOL. “That’s when we really need to exchange that lens, when it’s the wrong lens or power or [has a] huge refractive surprise,” she said. Another reason for exchange, Dr. Rocha said, is in a patient who has a trifocal or EDOF lens and, despite all correction of residual refractive error and/ or dry eye treatment, is having significant dysphotopsia. Lastly, she noted that a lens may need to be removed if it has been dislocated with damage to the IOL, such as in a traumatic accident or pseudoexfoliation syndrome. When performing an IOL exchange in cases where the capsular bag is intact, Dr. Rocha will use dispersive viscoelastic to try to open the capsular bag, especially around the haptics. Then she carefully prolapses the lens into the anterior chamber. She noted that this is generally easy with single-piece IOLs; this may be harder with a Crystalens (Bausch + Lomb) because of the design of the haptics. Dr. Rocha places the new lens in the bag and cuts the original IOL in the anterior chamber; placing the new lens makes it safer to cut the exiting lens. If the capsular bag is not intact, she checks whether the anterior capsule is intact. She said you should try to place the lens in the sulcus. A single- piece IOL should never be in the sulcus because these patients may develop pigment dispersion and UGH syndrome. A three- piece lens can be placed in the sulcus, Dr. Rocha said, noting that she likes the optic capture technique. Dr. Safran said that many times when he is taking out an old lens, it may be scratched or the wrong power or in some cases, he doesn’t know the power. Some lens types don’t do well over time, he said, noting that he will always remove a hydrophilic acrylic lens with a problem because Yeo Tun Kuan, MD Senior Consultant, Tan Tock Seng Hospital 11 Jalan Tan Tock Seng, Singapore 308433 tun_kuan_yeo@ttsh.com.sg ASIA-PACIFIC PERSPECTIVES