April 2020

CATARACT

Skill Focus
Keys to intrascleral haptic fixation


by Rich Daly Contributing Writer

A relatively new IOL fixation technique might offer some specific advantages, but it also requires unique surgical maneuvers, according to surgeons.
At the 2016 ASCRS ASOA Annual Meeting, Shin Yamane, MD, PhD, introduced this new method for intrascleral IOL fixation, using a transconjunctival approach without sutures or glue.
Since learning this technique, Nicole Fram, MD, has found it particularly useful when she wants to preserve conjunctiva and use small incisions.
“In addition, we have found in our series that there is a lower incidence of vitreous hemorrhage, as fewer sclerotomies are being made compared to scleral suture-fixated IOLs,” Dr. Fram said.
However, Dr. Fram noted that the procedure’s two-point fixation requires the surgeon to understand unique surgical maneuvers to avoid tilt, pupillary capture, and decentration.
“For this reason, counseling the patient preoperatively that they may need a second surgery is warranted for surgeons early in the learning curve,” Dr. Fram said.
Brandon Ayres, MD, said haptic fixation has become his practice’s most commonly used technique for IOL fixation. Dr. Ayres said he counsels patients about the various options for IOL fixation and tells them he will use the technique he thinks will work best for them. His use of suture fixation has become limited to situations where he needs to remove a large PMMA IOL or ACIOL, which already require a large wound.
“The Yamane technique allows us to keep wound size smaller and is a faster technique, but there are still problems with centration and tilt,” Dr. Ayres said. “When it comes to centration and accuracy, I still think suture-fixated IOLs outperform haptic fixation, and in young patients with no sign of retinal pathology, I may still opt for a Gore-Tex-fixated IOL.”

IOL selection and fixation technique

Dr. Yamane recommended using a 30-gauge thin-wall needle (TSK Laboratory), needle stabilizer (Geuder), and Yamane forceps (Katalyst Surgical), but other tools can also work to perform this fixation. Dr. Yamane recommends IOLs with PVDF haptics for this technique but any three-piece IOL could be used. Dr. Ayres described some of the differences in haptic materials.
“Most of the three-piece IOLs use PMMA for their haptic material, and the PMMA is easy to kink and break,” Dr. Ayres said. “The IOL from Carl Zeiss Meditec has haptics made of PVDF and are much more durable. For a surgeon new to the haptic fixation technique, I’d stick with the CT Lucia 602 [Carl Zeiss Meditec]; for more experienced surgeons it matters less what IOL you use.”
Dr. Fram said limited availability of the CT Lucia 602 has made that option less feasible. She also uses a 30-gauge thin-walled needle (Delasco), 25-gauge forceps (MicroSurgical Technology), anterior or posterior infusion, and a proper pars plana-assisted anterior vitrectomy technique. A vitrectomy is necessary for this technique, if not already performed in a prior surgery.
The tools Dr. Ayres identified include a 27-gauge or thin-walled, 30-gauge needle, AC maintainer, micro-anterior segment forceps, anterior chamber or posterior chamber infusion, marking pen, caliper, and low-temperature cautery. He also mentioned the Scleral IOL Fixation Solutions Pack (MicroSurgical Technology), which includes all needed equipment for the procedure except the IOL.

IOL power considerations

Dr. Yamane said the IOL power or A-constant considerations with the technique are almost the same as those for in-the-bag fixation. He calculates a 0.3 D myopic shift.
Dr. Fram has found that those considerations depend on the selected IOL. She looks at the recommended A-constant of the manufacturer and uses information from doctor-hill.com, as well as the biometry results. Dr. Fram aims for in-the-bag calculations (plano to –0.50 D) and has found the Holladay calculation most reliable.
Although Dr. Ayres uses a similar approach, he has experienced more variability with scleral- fixated IOLs.
“I tend to place my IOLs more posterior than other surgeons,” Dr Ayres said. “I like to place my IOLs approximately 3 mm posterior to the limbus. We have found that 50% of our patients with this technique are within 0.5 D of intended target, [and] those that fall outside 0.5 D tend to be on the myopic side.”

Eye marking and incision placement

The best way to mark the eye is through use of diathermy, Dr. Yamane said, but dyes are also acceptable. He then creates the main wound at 1:00 and the scleral tunnel at 3:30 and 9:30.
Dr. Ayres uses a centration guide, like an LRI or toric marker, to ensure 180-degree placement of the scleral tunnels. He creates sclerotomies at 12 o’clock and 6 o’clock.
“My preference is to make them 3 mm posterior to the limbus, and I make my sclera tunnel 2 mm in length,” Dr. Ayres said.

Preventing decentration

Decentration occurs when the marks and subsequent scleral tunnels are not 180 degrees apart and centered, Dr. Fram said. Tilt occurs when tunnel lengths are not symmetric or the distance from the limbus is not equal on each side.
Insertion angle of the needles is important to control tilt. The needle stabilizer helps to make the insertion angle constant.
“Decentration can be dealt with sometimes by trimming one haptic shorter,” she said. “However, if it is severe, then you can pick the side that looks better centered and redock the other side at the true 180 degrees. The haptic flange can be cut on a bevel and checked that it will feed into a new 30-gauge, thin-walled needle. The haptic is pulled back into the eye using 25-gauge forceps and placed on the iris. This haptic can then be and redocked in the new 30-gauge needle at a proper 180-degree location for better centration.”
To prevent tilt, Dr. Fram maintains the side with the proper haptic tunnel and entry. Additionally, the shorter pass should be redocked with a more symmetric tunnel length or distance from the surgical limbus.
“For pupillary capture, a peripheral iridectomy should be attempted first,” Dr. Fram said. “An ultrasound biomicroscopy should also be performed to evaluate tilt. If it’s amendable, a [peripheral iridectomy] may be sufficient. If not, then the persistent optic capture of the pupil can be resolved by refixating the haptic closest to the side of the pupil that is captured. The new pass should be more posterior.”

Tips to ease Yamane

One tip Dr. Yamane recommends to help surgeons with the technique is to first practice inserting the haptic in the needle.
“After that, pay attention to the positional relationship between the wounds,” Dr. Yamane said.
Dr. Fram urged meticulous marking, moving the main incision temporally, and keeping the proximal haptic outside of the eye prior to docking.
“Understanding the tunnel length (1.5 mm) and orientation (20 degrees to the limbus) was also critical to shortening my learning curve,” Dr. Fram said. “I recommend practicing with a simulation model, such as SimulEYE [InsEYEt].”
Dr. Ayres agreed practice of the technique is critical and mentioned courses offered by ASCRS and the American Academy of Ophthalmology.
“Don’t forget to keep the eye formed, using an AC maintainer is critical in these cases,” Dr. Ayres said. “Talking the case through with a surgeon experienced in the technique is also helpful.”

About the doctors

Brandon Ayres, MD
Cornea Service
Wills Eye Hospital
Philadelphia, Pennsylvania

Nicole Fram, MD
Clinical instructor
Stein Eye Institute
University of California,
Los Angeles
Los Angeles, California

Shin Yamane, MD, PhD
Assistant professor
Department of Ophthalmology
Yokohama City University
Medical Center
Yokohama, Japan

Relevant disclosures

Ayres
: Alcon, Carl Zeiss Meditec, MicroSurgical Technology
Fram: None
Yamane: None

Contact

Ayres
: brandonayres@me.com
Fram: nicfram@yahoo.com
Yamane: shinyama@yokohama-cu.ac.jp

Keys to intrascleral haptic fixation Keys to intrascleral haptic fixation
Ophthalmology News - EyeWorld Magazine
283 110
283 110
,
2020-04-13T13:39:24Z
True, 4