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Cyclodiode laser has traditionally been used to treat high intraocular pressures and refractory cases of glaucoma not amenable to medical or other surgical options. The cyclodiode laser ablates the ciliary processes, reducing aqueous humor formation and lowering the intraocular pressure. The development and advancement in cyclodiode laser delivery devices have expanded treatment options for varying glaucoma subtypes. This activity reviews the background of cyclodiode laser as a treatment for glaucoma, its mechanism of action, indications, contraindications, surgical techniques available, and potential complications, and highlights the role of the interprofessional team in evaluating and managing patients undergoing this treatment. Objectives: Evaluate the available cyclodiode laser devices and their mechanism of action in glaucoma. Identify the indications for cyclodiode laser therapy. Assess the various surgical techniques available for cyclodiode treatment. Communicate the complications and risk factors for poor ocular outcomes. Access free multiple choice questions on this topic.

Glaucoma represents a spectrum of diseases that culminates in a progressive optic neuropathy characterized by optic disc excavation, loss of the retinal ganglion cells, and eventual visual field loss.[1][2] Intraocular pressure (IOP) is a significant primary risk factor and is the only modifiable risk factor for which treatment can be directed to slow or halt progression.[3] In glaucomatous disease, the main treatment sites to lower IOP are targeted to improve the facility of aqueous outflow from the eye or reduce aqueous production at the ciliary processes. Destruction of the ciliary body secretory epithelium to lower aqueous humor production and treat refractory or uncontrolled glaucoma has been advocated since the early 1930s.[4] Cyclodestruction has been performed using various methods, including diathermy, surgical excision, cryotherapy, ultrasound, and laser. Cyclodiode laser has become the mainstay treatment of ciliary body destruction using an 810 nm laser.[2][5] Various subtypes of cyclodiode laser now exist, from Trans-scleral cyclophotocoagulation (TCP) to Micropulse (MP-TCP) and Endocyclophotocoagulation (ECP).[6]

Complications following diode laser treatment vary depending on the type of diode laser employed, the underlying glaucomatous diagnosis, and the treatment protocol administered.[5] Commonly observed complications following diode laser include transient mild-moderate discomfort, conjunctival hyperemia, conjunctival burns, conjunctival hyperpigmentation, transient pupillary ovalization, and transient anterior chamber inflammation. More serious reported complications include hyphaema, vitreous hemorrhage, loss of visual acuity, cataract formation, lens subluxation, malignant glaucoma, choroidal hemorrhage, scleral perforation, hypotony, phthisis bulbi, and sympathetic ophthalmia.[21] Energy levels in TCP greater than 60J per treatment session are generally found to be at higher risk of developing postoperative hypotony. Similarly, the greater number of shots delivered in TCP is a significant risk factor for hypotony.[14][21] Other ocular risk factors associated with higher rates of hypotony include neovascular glaucoma and a higher pre-treatment IOP. Sympathetic ophthalmia is an infrequent complication from TCP, and the exact rate of occurrence is estimated to range from 0.03 TO 0.17%.[21] MP-TCP is noted to have an improved safety profile compared to traditional TCP regarding rates of hypotony and phthisis bulbi, presumably due to its improved control in reducing collateral thermal tissue damage. Longer treatment duration and higher power settings are associated with higher rates of complications.[19][20][22] Potential risks from ECP include all of the above for transscleral cyclodiode except for conjunctival surface burns. Most studies suggest a lower rate of severe postoperative complications than TCP, particularly when power levels less than 500mW are applied.[8][9] Given the intraocular nature of this procedure, other risks are present, including damage to the crystalline lens, zonular damage, iris damage, retinal detachment, and endophthalmitis. To date, no cases of sympathetic ophthalmia have been reported from ECP.[5]

Cyclodiode is an evolving treatment for glaucomatous disease, not solely resigned to managing refractory cases. A thorough preoperative workup and assessment must ensure patient suitability and attain satisfactory IOP reduction while minimizing potential postoperative complications. The patient consents to and is made aware of other treatment modalities that can be considered. On the day of surgery, the interprofessional team consists of an ophthalmic surgeon, ophthalmic nurses, and operating room staff. The team must ensure consent is obtained and the eyes for surgery are appropriately marked. Local laser safety protocols and procedures must be followed during the procedure. The nursing staff postoperatively ensures the patient's prescription is available, informs them of the drop regime, educates them on potential symptoms and complications, and arranges further follow-up in the eye clinic.