Sir,

Transscleral cyclophotocoagulation (TSCPC) is used to treat patients with refractory glaucoma.1, 2 TSCPC is a destructive procedure of the ciliary processes leading to decreased aqueous humor production.2 Because of complications such as hypotonia and phthisis bulbi, TSCPC is usually opted as a therapy for eyes with low visual potential and poor response to other medical or surgical interventions.2 However, IOP changes in the very early postoperative period and its clinical implications have not been addressed yet. This study evaluates the immediate changes in intraocular pressure (IOP) after TSCPC.

In a prospective interventional design, we evaluated the changes of IOP after TSCPC in a series of 10 patients with refractory glaucoma. IOP was measured with a Tono-Pen Avira (Reichert, Buffalo, NY, USA) right before the procedure, immediately after TSCPC, 3 h, 1 day, 3 days, 7 days, and 28 days thereafter. The procedures were performed in the operating room under retrobulbar anesthesia using 2 ml of 2% lidocaine, and intravenous sedation with propofol and cardiopulmonary monitoring by anesthesia team. The starting laser parameters were power of 2000 mW and duration of 2000 ms. On the basis of the pop-sound response, power was adjusted on the steps of 250 mW.3 All patients received subconjunctival injections of 4 mg dexamethasone at the conclusion of surgery. Those with immediate post-laser high IOP received intravenous 20% mannitol (1 g/kg). Postoperatively, all patients were instructed to use topical 1% prednisolone acetate 4 times daily (tapered over a 6 weeks period), and glaucoma medications were adjusted as required.

Table 1 summarizes the patients’ demographic data, laser settings, and IOP changes after TSCPC. All but one patient showed a significant increase in IOP immediately after TSCPC (mean IOP, 31.4±9.8 before vs 44.3±14.3 mm Hg immediately after the procedure; P=0.012, Wilcoxon-signed rank test). Immediately after the procedure, all patients had IOP ≥30 mm Hg, 5 (50%) had IOP ≥40 mm Hg, and 3 (30%) had IOP ≥50 mm Hg (Table 1). Three hours after the procedure, despite receiving the intravenous mannitol, six patients had IOP ≥30 mm Hg and two had IOP ≥50 mm Hg. However, on the first postoperative day, no patient had IOP ≥30 mm Hg. The pattern of IOP changes during the first month after TSCPC is depicted in Figure 1.

Table 1 Data summary of 10 glaucoma patients who underwent transscleral cyclophotocoagulation
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Figure 1
figure 1

The intraocular pressure profile after transscleral cyclophotocoagulation.

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The main finding of the present study was a significant IOP elevation in almost all eyes immediately after TSCPC. This could be dangerous in patients with advanced glaucomatous optic nerve damage and may result in further optic nerve injury, temporary central retinal artery occlusion, and ischemia-reperfusion retinal injury.4 The laser-induced coagulative necrosis and disruption of ciliary processes may increase intraocular volume by creating air bubbles (which are typically heard as ‘pop-sound’ during TSCPC)2, 5 and lead to immediate IOP rise, which could not be handled properly by the impaired trabecular meshwork. The IOP elevation also happened in two patients that received only 12 spots of laser therapy with a power and duration around 2000–2500 mW and 2000–2800 ms, respectively. Therefore, we believe that the IOP needs to be checked immediately after TSCPC and managed properly if it is elevated.