Patients who are aphakic and no longer tolerate contact lenses are good candidates, as are other patients who are at risk of lens dislocation. Dr. Garg has found the technique effective in patients who do not have normal capsules. “It’s really meant for when there is a lack of bag or sulcus fixation,” he added.
But scleral tunnel fixation isn’t perfect. “It’s not without its complications long term,” said Dr. Garg. The procedure is technically challenging, requires special instrumentation, and will not work in every eye.
A current or future bleb, previous surgery, a thin sclera, or insufficient vitrectomy can pose significant problems.
“Any procedure where you have disrupted the anterior hyaloid face, you have to be careful to do as complete a vitrectomy as possible,” Dr. Garg said. “You don’t want traction on the vitreous to cause cystoids macular edema and risk of infection.”
He also advised caution in conjunctivas with extensive scarring. “If the conjunctiva is scarred down, this procedure becomes more difficult because the conjunctiva has to be lifted up,” said Dr. Garg. “If someone has really scarred down, that’s where an alternative may be the better choice.”
Other relative contraindications include corneal decompensation or atrophic scleromalacia. “Make sure the sclera is healthy and you have enough to tunnel the haptic in,” Dr. Garg advised. “We are limited by the length of the haptics, so you have to make sure it’s not a huge eye.”
Dr. Agarwal and colleagues followed 208 eyes in 185 patients for 17 months and recorded a low incidence of complications. Early on, 6% had corneal edema, 2% had epithelial defects, and 2.5% had grade 2 anterior chamber reactions. Later, 0.4% had hyphema, 0.4% of haptics broke, and 1% of haptics were deformed.
Another 4.3% had optic capture, 3.3% IOL decentration, 2% haptic extrusion, 1.4% subconjunctival haptics, 2% macular edema, and 2% pigment dispersion. Re-operation was required in 7.7% of patients.
Best corrected visual acuity (BCVA) was 20/40 or better in 40% of this group and 20/60 or better in 49%.
In a second cohort of 60 eyes with a follow-up of 5 years, Dr. Agarwal and colleagues reported that 35% had optic tilt of roughly 3º between the IOL and the iris. The mean residual cylinder was 0.5 D (±0.5 D). There was no correlation with BCVA.
“We don’t have really long-term data on the technique,” said Dr. Garg. “You can get migration of the haptics out of the tunnel, which on occasion has to be retunneled, or a patch graft has to be placed to make sure it doesn’t extrude through the conjunctiva. But by and large, it’s a really stable method of fixation.”
He described a recent case of an IOL that stayed intact even though the penetrating keratoplasty wound dehisced after a patient bumped his eye against the ledge of a table. “The scleral fixation of the haptics actually prevented dislocation of the IOL,” said Dr. Garg.