Practice makes perfect when adopting this method for intrascleral IOL fixation.
The Yamane technique, first described by Shin Yamane and colleagues,1 is of use for intrascleral IOL fixation when a patient is aphakic without capsular support. It sparked my interest since I was seeking a solution for cases where iris fixation was not an option.
The technique offers an elegant and effective way to fixate the IOL in complex cases. I have had the opportunity to perform it several times and my first few cases provided me with some key takeaways as well as offering a unique perspective to identify areas for further improvement.
Thorough preparation, including practising in two wet labs before the first case, is a must, and the learning curve with the Yamane technique can be steep. However, it is also short. And whilst mastering a method usually requires a large number of cases, I have achieved great outcomes quickly by going back and reviewing videos and analysing my early experiences.
I was referred a patient with a posterior capsule tear during cataract surgery whose IOL had slipped nasally half inside and half outside the bag. The patient could no longer see well because the optic edge was now in the centre of the visual axis.
IOL exchange was scheduled. The dislocated IOL was carefully removed from the capsular bag and then cut into three pieces using 19g Packer/Chang IOL cutters (MicroSurgical Technology [MST]) for atraumatic removal from the anterior chamber. Following IOL removal, I inserted a CT Lucia lens (Zeiss) and both haptics into the anterior chamber.
I then sutured the main incision (which was larger than usual because of the IOL removal) with the intention of avoiding excess fluid leakage and maintaining the good pressure required for needle placement. I used a 23g Ahmed micro-grasper (MST) through the paracentesis for entry to grasp the haptics.
Placing the second haptic inside the anterior chamber made grasping and threading the haptic into the lumen of the needle much more challenging because the haptic slid into the angle. With hindsight, I should have left the trailing haptic outside of the eye; I will do so in the future.
In the next case, the patient’s lens had fallen into the posterior chamber during cataract surgery and the capsule was completely lost. During the pars plana vitrectomy and lensectomy, they endured a sector iridectomy. The patient presented to me with aphakia, no capsule, some loss of iris tissue and cystoid macular oedema.
I again elected to proceed with scleral fixation utilising the Yamane technique. This time, I used an AC maintainer included in the scleral IOL fixation solutions pack (SFP-1001, MST) to keep the eye firm.
The needle placements went well, and there was no fluid egress even with the trailing haptic exposed through the primary incision. The procedure went smoothly and as planned. The trailing haptic can also secure the IOL from falling back into the vitreous cavity, especially in this case because there was no capsular support and iris tissue was missing.
I proceeded with the iris repair, which required suturing of the sphincter. I used 23g Ahmed micro-tying forceps (MST) to hold each edge of the tear as I passed the needle (10-0 prolene suture on CTC-6 needle) through to complete the repair.
At the end of the case, I saw that the IOL was not perfectly centred even though I had been careful with the scleral measurements, so I pulled the haptic to one side to centre the optic. I then trimmed the excess haptic material and mushroomed and reburied the tip. The IOL was perfectly centred and there was no tilt at all.
Sometimes it can be difficult to mark accurately because the limbus is not always clearly defined. One can miss by half a millimetre due to difficulty in identifying a clear entry point. In this case, even though one marks at 2.5 mm, this may not actually be 2.5 mm from the limbus.
I believe this is what happened during the second case described above when I realised that the IOL was not well centred. One needle entered further from the limbus than the other, which affected the IOL positioning. Of note, each needle pass is performed by a different hand and at a different angle —it is difficult to be perfectly symmetrical but awareness of the issue certainly helps.
To know exactly where the positioning and entry points are (2.5 mm posterior to the limbus and 2 mm across), I like to open the conjunctiva and measure directly on the sclera to see as much as I can. Surgeons who have experience with this technique can go through the conjunctiva, but I feel it is less stressful when you have better visibility to watch the needle pass under the sclera before making the turn.
The sclera can also be held to prevent the eye from rotating, which helps with the needle tunnelling. If going directly through conjunctiva, the scleral tunnel is not visible. Finally, when turning the needle to enter the eye, go deep and not shallow: turn and go straight down and then come back up to visualise the bevel of the needle.
Keep in mind that the needles will be passed by both hands and that each hand will act differently: one comes forward while the other goes back. There are going to be differences between your hand positions, which is not a big problem, but one need to be mindful of this and make adjustments to get the same result from both hands. This is something that can be practiced with simulation model eyes.
Fixation of the globe is very important; otherwise the eye rotates, so the hand positions should be thought out ahead of time.
One might think that the haptic should thread directly into the needle, but in my experience, it is the opposite: threading the haptic is much easier if the needle is aimed toward the haptic while holding the haptic still. I use the 30g thin-wall needles with specialist holders from the scleral IOL fixation solutions pack (MST), which allow for manoeuvrability and control during this delicate step. To manipulate the haptic, my preferred micro-instrument is the 23g Ahmed micro-grasper (MST), which is a versatile micro-instrument for the anterior chamber.
My final recommendation would be to choose your cases wisely and have retina support available. Always prepare your equipment in advance.
I opt for the CT Lucia IOL (Zeiss) with PVDF haptics, which I find has the right proportion of flexibility and resistance to breaking. I also use the scleral IOL fixation solutions pack (MST), which includes the essential elements to perform the technique, including three 30g thin-wall needles with silicone hubs, two specialist needle holders, an AC maintainer, a marker and a calliper.
The Yamane technique can be easy to learn if one is prepared and well equipped. Even if things do not go perfectly the first couple of times, practice will help you learn from your mistakes and it will get easier!