A novel ultrasonic intraocular lens (IOL) cutting tip and IOL holding forcep

Abstract

To address the challenges related to IOL explantation and associated complications, we have developed an innovative tip that utilizes the ultrasonic power of phaco machine for efficient IOL cutting. The tip can be easily screws into phaco machine, while the other end is forked with sharp inner margins. This cutter is complemented by the ergonomically designed microforceps which are inserted through a side port to grasp the lens securely during cutting.

Intraocular lens (IOL) explantation or exchange is a challenging task in ophthalmic practice. IOL explantation is required in various conditions such as broken IOL haptic during implantation, IOL dislocation, IOL opacification, refractive surprises, unhappy patients complaining of halos and glare due to ring IOL and UGH syndrome, etc.[1,2,3] If IOL explantation not done appropriately, it can lead to bullous keratopathy, corneal decompensation, descents membrane detachment, posterior capsule rent, and vitreous loss.[3,4]

Various techniques for IOL explantation have been reported previously; however, they are difficult to perform and can be traumatic to the wound and corneal endothelium affecting visual outcomes. The common practice to explant an IOL is to remove it by enlarging an incision or by bisecting the IOL using scissors in the anterior chamber and pulling out the pieces through the corneal wound using forceps.[5] Various scissors used for cutting the IOL are bulky, thus could result in an increase in wound size up to 3 mm or damage to the corneal endothelium. “Twist and out” technique involves the rolling or refolding of an IOL around a straight forceps in the anterior chamber and pulling it out. This requires the swift movement of the wrist, by a skilled surgeon and could possibly stretch the wound, whereas “Grasping, pulling and refolding” of the IOL technique involves the grasping and pulling of IOL toward the main incision and refolding inside the corneal incision.[5] Bhaumik et al.[2] described a refolding and reloading technique of IOL explantation using a device comprise of modified cartridge and modified snare. Although the device was able to pull out all types of single-piece IOL through the original wound without extension or compromising its integrity, the technique was unsuccessful with thicker IOL, silicone IOL, and multipiece IOLs.[2]

Thus to overcome the surgical challenges and preserve the integrity of ocular structures such as corneal endothelium and anterior chamber angle, simplified techniques or easy-to-use devices are required. Thus, here, we describe an innovative IOL cutter and its technique for IOL explantation through the corneal incision 2.2 mm.

Innovation

The device was conceptualized and designed by Dr Neha Dholakia and hence named as “Dholakia ultrasonic IOL cutter.” A cutter tip of fixed “V” shaped configuration [Fig. 1a] was constructed using titanium material with an angulation of 35 degrees. The size of the cutter is 2.0 mm and was manufactured by Ushma Technologies. The “V” shape of the cutter uses ultrasonic energy to cut both hydrophobic and hydrophilic IOLs, unlike mechanical cutters where jaws usually open and close. Each tip has been customized for a specific phaco machine handpiece. Thus, the tip of the cutter is a combination of six lengths, three threads, and two widths (thickness); thereby, the length varies between 22–26 mm. Similarly, the three threads were manufactured to match the specific phaco handpiece. The cutter in combination with specially designed serrated jaw-shaped forceps of 2.2 mm with a neck of 0.8 mm [Fig. 1b] can yield the best results. Forceps are made up of steel material since it has to be strong. Forcep opens in the vertical direction similar to a crocodile mouth, whereas the grip is designed horizontally which can be held between the thumb and index finger. The forcep goes through a side port and has a curve for ease of use.

Figure 1.

Illustrates Dholakia IOL cutter with fixed “V” shaped configuration (a), forcep with the serrated jaw (b) and Dholakia cutter with attached silicone sleeve (c)

Wet lab experimentation and in vivo technique

This newly developed device for IOL cutting and explanation was tested, practiced, and mastered in a web lab setting. The temperature of the tip of the cutter was checked in a web lab setup and was found to be similar to the temperature of the phaco tip in a similar environment. We tried this device on both hydrophilic and hydrophobic IOLs without any difficulties. The phaco probe is usually primed with a normal tip which is then removed and an IOL cutter tip is screwed in and tightened up followed by a silicon sleeve is attached over it [Fig. 1c]. The IOL can be held with forcep firmly, and the cutter tip can be positioned such that IOL get stuck in the “V” shape cutter groove, and using the low phaco power, IOL can be cut into 3–4 slivers and then can be removed via corneal incision without extending it. Video 1 demonstrates the in IOL cutting in wet lab. The Video 2 demonstrates the in vivo IOL cutting and explantation using the forcep where, after obtaining prior informed consent, the forcep was introduced through the side port with a left hand to grip the IOL and through corneal incision cutter had been inserted with right hand and position such that IOL gets stuck in the groove where cutter is moved forward to cut the IOL in multiple pieces. The pieces can be aligned parallel to the incision and removed via the wound without damaging it. These instruments can be cleaned with ultrasonic cleaner at 30 degrees using non-enzymatic detergent liquid 0.5%. The instruments can be rinsed using distilled water followed by hot dry air. Also they can be autoclaved for a planned surgery or can be sterilized using ethylene oxide (EtO) for emergency use specifically in case of broken haptic at the time of insertion.

Discussion

The rate of IOL exchange has been reported to be 0.77%.[6] A careful approach is required while explanting the IOL in order to minimize the postoperative complications. Removal of IOL can stretch the corneal incision and thereby causing astigmatism. A study by Ucar et al.[5] reported increase in astigmatism after IOL explantation using incision enlargement technique as compared to IOL bisecting or “grasp, pull and refold” technique; however, with Dholakia cutter, the IOL can be cut and removed through the corneal incision of 2.2 mm without extending it. Explantation of the IOL or its part needs to be done properly as residue or fragment of the IOL in the eye can damage the corneal endothelium as Hoffman R has described retained IOL fragment as a cause of corneal decomposition.[7] The methods of IOL explantation depend upon the material of IOL.[8] Usually, hydrophilic IOLs materials are softer compared to hydrophobic IOLs.[9] It has been suggested that hydrophobic foldable IOLs can be refolded and explanted via the original corneal incision; and thicker IOLs (>24 diopter), opacified, three-piece, and hydrophilic IOLs can be cut into smaller fragments before explantation.[8] Nevertheless, Dholakia cutter can be used for explantation of both hydrophilic and hydrophobic IOLs. The device was also successful in cutting thicker and opacified IOLs in vivo. Secondly, it cuts the IOLs with phaco power as low as 10% with certain machines. Various IOL cutting scissors have been used previously for bisecting the IOL and include Mackool cutter[7] or Vannas scissor;[5] however, it requires surgical manipulation or rocking of IOL which can result in complications such as posterior capsule rupture, corneal edema, or decompensation.[5,7] Since Dholakia cutter comprises a fixed “V” shape groove, it eliminates the need for surgical manipulation, and the following suggestions can be considered while using the Dholakia IOL cutter.

1. For right-handed surgeons, the right hand can be used for holding the phaco probe where the tip can cut the IOL from the periphery to the center while simultaneously counter pressure can be given using the left hand toward the main incision.

2. IOL can be cut in three to five parts depending upon the experience; ideally, it is suggested to cut the IOL in three parts such that each part is a width of 2 mm approximately so that it can come out of 2.2.mm corneal incision.

3. Due to the learning curve, it is recommended to practice IOL cutting in vitro with cheap foldable IOL to get comfortable. Adequate water can be poured in a shallow tray or a lid of a box. Using water would provide better visualization.

4. In vivo to prevent damage to the endothelium, one can keep the cutting tip at the center of the anterior chamber (AC) where the space is maximum. Also continuous use of visco-elastic is must to protect the corneal endothelium.

5. Instead of moving the cutter forward, the left hand with the forcep can be moved backward toward the main incision to feed the IOL into the open jaws of the cutting tip. Simultaneous movement of the right hand forward and left hand backward gives the best results.

6. It is recommended to use the lowest power to cut the IOL. One can start with 50% power and then gradually decrease in steps of 10% till it cuts the IOL. Aspiration and vacuum have to be kept at zero. Irrigation should be low to prevent any turbulence. Also using a viscoelastic and reducing the bottle height can further help control the movement of the IOL pieces.

The novelty of this cutter lies in its fixed “V” shaped configuration and use of ultrasonic energy to cut the IOL, unlike the mechanical force used with conventional scissors. The advantage of ultrasonic energy is that it helps cut the IOL seamlessly without any jitter and less maneuvering in the eye, thereby reducing the damage to the corneal endothelium and posterior capsule. Also with this newly developed IOL cutter, one can easily explant the IOL without extending or stretching the wound. It does not require tilting of the IOL which otherwise required using conventional IOL scissors. The technique can be mastered easily with an easy learning curve as the threads of the tip have been customized to match with the specific phaco handpiece.

Thus, to conclude, the Dholakia ultrasonic IOL cutter is a simple, convenient device that can be considered for hydrophilic and hydrophobic IOL explantation.

Conflicts of interest:

We declare that Dr Neha Dholakia has a proprietary and commercial interest in the product described in the manuscript (Ultrasonic IOL cutter and forcep). However other authors do not have any conflict of interest.

Funding Statement

Nil.