Pars plana filtration: Trans-scleral contact diode laser cyclophotocoagulation

Dear Editor,

I read the erudite guest editorial on Minimally invasive glaucoma surgery (MIGS) in India – Is it time?[1] I could not agree more that the oldest MIGS procedure since 1990 is endocyclophotocoagulation (ECP) and cyclodiode laser.

I have been performing contact trans-scleral cyclodiode (TSCPC) laser for recalcitrant glaucoma for the past 20 years with excellent results in cases of neovascular and silicone oil glaucoma with excellent control of intra-ocular pressures (IOPs) and preservation of vision. An 810 Nm Iridis diode laser from Quantel (France) was the machine with a cyclodiode laser probe to deliver the laser to the ciliary body under local anesthesia. The beauty is the ease, repeatability, and the ability to titrate the therapy to the IOP.

The routine TSCPC reduces the aqueous humor formation by coagulating the proteins in the cells of the ciliary body and processes and is a cyclo-destructive procedure performed 1 mm posterior to the limbus over the pars plicata. However, the pars plana filtration described by Federman et al.[2] in 1987 using CW Nd YAG laser to punch holes [Video 1] in the pars plana 3-4 mm posterior to the limbus leads to IOP reduction by improving the uveoscleral outflow and damage to ciliary body vascular supply.

The settings used for pars plana TSCPC are a power of 1.2–1.8 watts, 1–2 seconds duration with 35–50 applications 3–4 mm posterior to the limbus for 270 degrees. The end point is achieving a pop sound in 30% of the laser shots. In our study of 120 eyes of neovascular glaucoma bevacizumab-assisted pars plana TSCPC showed promising results. With an IOP of 50–60 mmHg, a reduction was seen in 80% of the eyes to 20–30 mmHg with five eyes having phithisis bulbi. Additional TSCPCP was needed in 20 eyes after 3 months along with additional retinal surgery and panretinal photocoagulation in many cases for vitreous hemorrhage for proliferative diabetic retinopathy.

The advantages of this pars plana filtration TSCPC is that it is not cyclo-destructive with lower incidence of phithisis and improves prognosis for vitrectomy and regresses the rubeosis iridis. The side effects encountered are hyphema, hypotony, uveitis, pain, vitreous hemorrhage, and phithisis.

Cyclodiode laser with refinements such as micropulse is emerging not only as a treatment for refractory glaucoma but also as a primary procedure even in eyes with less advanced glaucoma and good visual potential.

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Conflicts of interest

There are no conflicts of interest.