Nonpenetrating surgery, cyclodestruction and postoperative lasers

Choose an operation by the required pressure and its risks

Glaucoma procedures lower pressure by improving outflow, creating a bypass or reducing aqueous production. Nonpenetrating surgery aims to improve outflow while initially retaining a thin tissue barrier to the anterior chamber. Cyclodestructive procedures target the ciliary body. Laser suture lysis and goniopuncture are postoperative adjustments to specific operations. These techniques are not interchangeable, and their names do not establish that they can achieve the low target needed by every advanced eye.

Start with the target pressure, documented progression, lens status, conjunctival condition, angle anatomy and visual potential. Discuss alternatives, expected medication use, follow-up demands and possible further surgery. Prior uveitis, neovascular disease, scarring or a very low target can substantially affect selection. A procedure described as less invasive may still cause serious sight-threatening complications.

Deep sclerectomy and viscocanalostomy

In deep sclerectomy, a superficial scleral flap is followed by deeper dissection to expose the outflow region while retaining a trabeculo-Descemet membrane. Aqueous crosses this thin membrane into a surgically created space, with drainage routes depending on technique. An implant may maintain the space. Antimetabolite use and the degree of subconjunctival filtration vary; it is misleading to claim that every nonpenetrating operation is entirely bleb-free.

Viscocanalostomy uses exposure and viscodilation of Schlemm canal with a different emphasis on internal outflow. Canaloplasty seeks circumferential canal catheterization and viscodilation, sometimes with a tensioning suture depending on the procedure. External and ab interno approaches differ in their incisions and tissue disruption. Canal-dependent procedures need an appropriate angle and a functioning downstream drainage pathway; they do not eliminate episcleral venous pressure.

Inadvertent perforation during deep sclerectomy changes the operation and may require conversion or revised postoperative management. Other complications include pressure spikes, hypotony, choroidal effusion and scarring. Explain that preservation of a membrane reduces some immediate risks but does not guarantee success or freedom from later intervention.

Goniopuncture and suture lysis

Nd:YAG goniopuncture can open the residual membrane after deep sclerectomy when its resistance limits outflow. Use gonioscopic visualization and assess whether the pressure problem is at that membrane or instead due to scarring elsewhere. Opening the membrane changes flow and can cause hypotony, inflammation or iris-related obstruction. It is not a substitute for diagnosing a blocked drainage implant.

Laser suture lysis adjusts resistance in a sutured trabeculectomy flap. Consider the postoperative interval, bleb appearance, pressure, chamber depth, wound integrity and antimetabolite exposure before releasing a suture. Releasing too much resistance can produce a shallow chamber and hypotony; releasing too little may leave damaging pressure. A thick conjunctiva or poorly visible suture may limit treatment. Digital massage, needling and medication changes have different indications and should follow examination.

Cyclodestruction

Transscleral diode cyclophotocoagulation delivers energy through sclera to the ciliary region. Conventional continuous-wave treatment, micropulse delivery and endoscopic cyclophotocoagulation differ in technique and evidence. Endoscopic treatment directly visualizes ciliary processes from within the eye; it requires intraocular access. Micropulse delivery includes intervals without energy and seeks to limit collateral injury, but it does not guarantee absence of damage or a particular pressure reduction.

Cyclodestruction has an important role in refractory glaucoma, selected seeing eyes and painful eyes with limited visual potential. Selection is individualized rather than restricted by an absolute rule that all treated eyes must be blind. Discuss inflammation, pain, pressure spikes, hypotony, visual loss and possible retreatment. Avoid presenting a device power or exposure duration as a universal protocol: pigmentation, anatomy, prior surgery and device settings affect treatment. Postoperative anti-inflammatory care and pressure review remain necessary.

Postoperative interpretation

A patient after deep sclerectomy has a deep chamber, healthy conjunctiva and persistently high pressure. Examine gonioscopically for the retained membrane and consider whether goniopuncture fits the cause. A patient after trabeculectomy has low pressure, choroidal effusions and a shallow chamber: suture lysis would worsen the problem. A painful eye with refractory pressure may benefit from cyclophotocoagulation after realistic discussion of visual potential and risks.

In each scenario, state which structure limits flow or which tissue will be treated. Check for infection, haemorrhage or aqueous misdirection before attributing every postoperative pressure problem to ordinary healing. Explain the follow-up plan, symptoms requiring urgent return and what counts as success for that particular patient.

Source: European Glaucoma Society guidelines and surgical curriculum.