IRIDOPLASTY

While no longer widely practised, laser iridoplasty can be helpful in managing angle-closure glaucoma in select cases, particularly those due to mechanisms other than pupillary block, Robert J Noecker MD told Glaucoma Day 2014 at the American Society of Cataract and Refractive Surgery annual meeting in Boston.

“It’s not something I practise every week or every month, but there are cases where it is appropriate.”

First described in 1973, iridoplasty uses an argon or equivalent solid state green thermal laser to coagulate the iris base, thinning it and shrinking it away from the angle. The most common indication is plateau iris, in which a bulging peripheral iris may keep the angle narrow or closed even after iridectomy, Dr Noeker said. Less common indications include nanophthalmos, lens-related glaucoma and angle closure following vitreoretinal procedures.

Plateau iris often results from anteriorly positioned ciliary processes, which push the peripheral iris into the angle, Dr Noecker said. This often can be clearly seen using ultrasound imaging before surgery.

Dr Noecker usually starts treatment with a laser iridectomy. This also helps identify the cause. If angle narrowing results from lens issues, iridectomy usually opens the angle as it relieves the aqueous pressure pushing the iris into the angle. But if it is primarily anteriorly placed, ciliary processes pushing the iris into the angle, iridectomy often has little or no effect as aqueous pressure is at best a secondary cause. In cases with residual angle closure, Dr Noecker may move on to iridoplasty once iridectomy-associated inflammation has subsided.

Peripheral iris

Iridoplasty generally involves targeting the peripheral iris with 24 to 32 spots of 200 to 500 micron size at 200 to 400 mW for 0.2 to 0.5 seconds each. These relatively long, high-energy pulses enable coagulation of not only the iris surface but also the ciliary processes behind it, allowing the iris to move posteriorly away from the angle, Dr Noecker said.

For nanophthalmos, iridoplasty may be combined with iridectomy and gonioplasty as needed to keep the angle open as the lens grows, Dr Noecker said. Similarly, iridoplasty can be helpful in cases of phacomorphic angle closure to keep the angle open until lens extraction is possible.

Vitreoretinal procedures including scleral buckle and panretinal photocoagulation may also cause ciliary body oedema, narrowing the angle. Iridectomy is the first choice, but iridoplasty may also be helpful. In those cases you want to shrink the ciliary processes as well, Dr Noecker said.

Iridoplasty is also useful for treating peripheral anterior synechiae of less than six months’ duration, and in eyes in which iridectomy is not possible, Dr Noecker said. When used appropriately it is effective and generates few complications.

Robert Noecker: noeckerrj@gmail.com