A 50-year-old male presented with progressive blurred vision, photophobia, and eye pain. On examination, there was conjunctival redness, a mid-dilated pupil, and a shallow anterior chamber in the right eye. He has been treated both medically and surgically for the condition but showed no improvement. The following procedure incorporates a device to aid drainage. Identify the device.

Correct Answer: A. Ex-PressTM implant

The clinical presentation—progressive blurred vision, photophobia, eye pain, conjunctival redness, mid-dilated pupil, and shallow anterior chamber—is classic for acute angle-closure glaucoma (AACG). The patient has failed both medical and surgical management, indicating refractory glaucoma requiring a glaucoma drainage device (GDD). The Ex-PRESS™ implant is a non-valved, micro-invasive glaucoma surgery (MIGS) device that creates a direct aqueous humor drainage pathway from the anterior chamber to the subconjunctival space. Unlike larger tube shunts (Ahmed, Molteno, Baerveldt), the Ex-PRESS™ is a stainless-steel, pre-loaded implant (50 µm lumen) inserted under a scleral flap, offering lower postoperative inflammation and faster visual recovery. It is particularly suited for refractory angle-closure glaucoma where conventional surgery has failed, as it bypasses trabecular and Schlemm's canal pathways entirely. The device's small profile and minimal tissue trauma make it ideal for eyes with compromised anterior segments (shallow chambers). In Indian practice, the Ex-PRESS™ is increasingly used in tertiary centers for post-AACG refractory cases where laser peripheral iridotomy and conventional filtration surgery have been exhausted.

Why the other options are wrong

B. Ahmed glaucoma valve — The Ahmed valve is a valved tube shunt designed for open-angle glaucoma and secondary glaucomas, not angle-closure. While it can be used in refractory cases, it is larger (14 mm), requires more extensive surgery, and causes greater postoperative inflammation than Ex-PRESS™. The question specifically asks for a device that aids drainage in a refractory angle-closure case—Ahmed is second-line, not first-line MIGS. C. Molteno implant — The Molteno is an older, non-valved tube shunt (larger diameter, 0.76 mm) used in advanced glaucomas but associated with higher rates of hypotony and chronic inflammation. It requires extensive conjunctival dissection and is rarely used in modern Indian practice for angle-closure glaucoma. The Ex-PRESS™ has largely superseded it due to lower morbidity and faster recovery. D. Baerveldt implant — The Baerveldt is a large-diameter, non-valved silicone tube shunt (0.76 mm) primarily indicated for open-angle glaucoma with severe optic nerve damage. It is more invasive than Ex-PRESS™, requires longer surgical time, and is not preferred for refractory angle-closure glaucoma in Indian tertiary centers. The question's emphasis on a device that aids drainage in a failed angle-closure case points to MIGS, not conventional tube shunts.

High-Yield Facts

Mnemonics

MIGS vs. Macro Shunts (MIGS-M) Mini (Ex-PRESS™, iStent) = Mild-to-moderate, Minimal trauma, MIGS. Macro (Ahmed, Molteno, Baerveldt) = Moderate-to-severe, More inflammation, More invasive. Use MIGS first in refractory angle-closure; escalate to macro shunts if MIGS fails. Valve vs. Non-Valve (VAN) Valved = Ahmed (opens at 8 mmHg, prevents hypotony). All others = Non-valved (Molteno, Baerveldt, Ex-PRESS™). Non-valved risk early hypotony; valved safer in high-IOP cases. Ex-PRESS™ is non-valved but small, so hypotony risk is lower than larger non-valved shunts.

NBE Trap

NBE may pair "refractory glaucoma + tube shunt" to lure students toward larger, older devices (Ahmed, Molteno, Baerveldt) without recognizing that MIGS (Ex-PRESS™) is now preferred first-line for refractory angle-closure in modern Indian practice, especially when anterior chamber is compromised. The trap is conflating "refractory" with "needs big surgery."

Clinical Pearl

In Indian tertiary centers, a 50-year-old with post-AACG refractory glaucoma (failed LPI + filtration surgery) presenting with shallow anterior chamber is a classic candidate for Ex-PRESS™ MIGS, as it avoids extensive conjunctival scarring and allows future surgery if needed—critical in a young-ish patient with decades of vision ahead.

_Reference: Robbins Ch. 29 (Glaucoma pathophysiology); Harrison Ch. 229 (Acute angle-closure glaucoma); Bailey & Love Ch. 37 (Glaucoma surgery and GDD)_