intraocular lens rotation in cataract surgeries

Preventing Posterior Capsular Opacification Through IOL Rotation in Cataract Surgeries

Cataracts are the most common cause of blindness worldwide, characterized by a clouding of the lens. The only means of treating cataracts is surgical intervention by removing the opaque lens, which restores high visual quality. However, a secondary reduction of visual quality, termed posterior capsule opacification (PCO), develops in 20%-40% of patients within 2 to 5 years after surgery1. This article introduces a method to further remove residual lens epithelial cells (LECs) left in the capsular bag in cataract surgery by rotating the intraocular lens (IOL) to prevent PCO.
PCO is a process caused by LECs, which are inevitably left in the capsular bag following cataract surgery and then begin to proliferate and migrate2. During phacoemulsification, a capsular bag is generated by continuous curvilinear capsulorhexis in the anterior capsule, which comprises a part of the anterior capsule, the equatorial capsule, and the entire posterior capsule2,3. In most patients, an IOL is implanted into the capsular bag. A transparent capsular bag, especially the posterior capsule, permits the light to transmit into the eyes, which is necessary for good postoperative visual quality4. A proportion of LECs are usually still attached to the capsular bag. As a reaction to the surgical trauma and a foreign body response toward IOLs, the residual epithelial cells start to proliferate and occupy first the remaining part of the anterior capsule, and then all available surfaces, including the surface of IOL and, most importantly, the previously acellular posterior capsule4. Subsequently, cells continue to divide, ultimately covering the entire posterior capsule and affecting the visual axis. The following changes, including fibrosis and regenerative form5, can cause significant visual impairment6. 
PCO that affects visual acuity can be treated with capsulotomy of the posterior capsule, usually by a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser and sometimes a surgical procedure4. Recent studies report that the incidence of Nd:YAG capsulotomy for treating PCO 3 years after surgery is between 5% and 20%7,8. However, this procedure can break the normal posterior capsular morphology and wrinkle the posterior capsule, thus likely affecting the position of IOLs, which is unfavorable to the long-term visual outcome of IOLs, especially multifocal IOLs, and toric IOLs6. Advances in surgical procedures, IOL design, the pharmacological inhibition of LEC proliferation, and the induction of LEC apoptosis have been confirmed useful in preventing PCO, most of which target the LECs9. 
LECs are normally distributed over the inner side of the anterior lens capsule in single-layer form1. LECs distributed in the area around the equatorial lens are the natural site of division, which is known as the germinative zone, while the dividing cells are also observed on the anterior capsule10,11. It has also been shown that equatorial cells can proliferate and migrate in the posterior capsule12. Residual LECs in the capsular bag are responsible for PCO. If LECs in the germinative zone are cleared as much as possible during cataract surgery, the possibility of PCO occurring postoperatively decreases as a consequence. As far as it is known, routine phacoemulsification does not include a procedure to remove equatorial LECs. In a study in India, the author proposed that rotation of the IOL by a Sinskey hook13 in the capsular bag decreases PCO and Nd:YAG capsulotomy rate.
Here, we introduced a method by rotating the IOL using an irrigation/aspiration (I/A) tip in the capsular bag to prevent PCO in cataract surgeries. The rationale of this method relies on the mechanical contact between the IOL and the capsular bag, especially the equatorial area, to remove residual LECs. Compared with treating PCO using Nd:YAG capsulotomy, the prevention of PCO maintains the integrity of the posterior capsule and the correct position of IOLs. Additionally, this method is cost-effective and requires no extra tools, which applies to cataract phacoemulsification and IOL implantation. Different from anterior capsule polishing, which is conducted using an I/A tip in the polishing mode of the phaco system6,14, the rotation of the IOL is conducted after the IOL implantation and is supposed to further remove visible lens matter (cortex) and cells.

Author Spotlight: Enhancing Visual Outcomes in Cataract Surgery: A Novel Technique to Prevent Posterior Capsular Opacification Through IOL Rotation 

Rotating the Intraocular Lens to Prevent Posterior Capsular Opacification in Cataract Surgeries

This research describe a novel technique to enhance the removal of residual lens epithelial cells that may remain in the capsular bag. Foreign cataract surgery by rotating the intraocular lens to prevent the posterior capsular opacification. The primary treatment for PCO is capsulotome.However, this procedure can cause changes to the shape of the posterior capsule, which may impact the placement of IOLs. This could potentially lead to suboptimal, long-term visual outcomes for patients with multifocal or toric IOLs. We have developed a technique for preventing PCO in cataract surgery by rotating the IOL inside the capsular bag, using Envision and aspiration tip.This method for preventing PCO is simple and cost effective. It only requires one additional step during cataract surgery, reducing the likelihood of PCO and the need for future treatments. We plan to perform extensive research on various IOL designs and PCO with a significant number of participants included in both rotating and non-rotating designs.Additionally, we'll conduct in vitro experiments on animal eyes to determine the effects of IOL rotation on equatorial cells.

Watch this Scientific Journal Video about Intraocular Lens Rotation in Cataract Surgeries at JoVE.com

Intraocular Lens Rotation in Cataract Surgeries  

After preparing the patient and phacoemulsification device system, incise the cornea and open the capsule with a continuous curvilinear capsulorhexis using Utrata capsulorhexis forceps under viscoelastic conditions. Perform cortical cleaving hydrodissection by injecting the balanced salt solution or BSS under the anterior capsule flap using a blunt tipped cannula. Perform hydro delineation by injecting BSS into the substance of the nucleus to separate the harder nucleus from the peripheral softer nucleus.Then select the chop mode, bury the phaco tip into the nucleus center, and insert it under the anterior capsule flap cracking the nucleus into two pieces. Next, set the machine to irrigation and aspiration mode. Use an irrigation and aspiration tip to remove the soft depa nucleus and peripheral cortical material.Fill the capsule bag and anterior chamber with viscoelastics. Load a foldable single piece intraocular lens into a prefilled injector cartridge with viscoelastic. Now, introduce the injector tip through the incision, and insert the IOL by pushing the injector tail, allowing the anterior haptic to spread into the capsular bag.Remove the viscoelastic from the anterior chamber while rotating the IOL 360 degrees clockwise with posterior pressure using the irrigation and aspiration tip. Next, insert the irrigation and aspiration tip behind the optic part of the intraocular lens to aspirate residual fragments and viscoelastic inside the capsular bag. After inserting the IOL into the capsular bag as demonstrated earlier, use a Fenzl hook to rotate the intraocular lens clockwise at least 360 degrees.Slide the intraocular lens within the capsular bag side to side while applying slight pressure on the posterior capsule. A retro illumination image depicting posterior capsule opacification is presented. One year following the surgical procedure, a clear and transparent capsular bag was observed.

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Research

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148 Views.  Peking University Third Hospital. After preparing the patient and phacoemulsification device system, incise the cornea and open the capsule with a continuous curvilinear capsulorhexis using Utrata capsulorhexis forceps under viscoelastic conditions. Perform cortical cleaving hydrodissection by injecting the balanced salt solution or BSS under the anterior capsule flap using a blunt tipped cannula. Perform hydro delineation by injecting BSS into the substance of the nucleus to separate the harder nucleus from the peripheral so...