Laser Peripheral Iridoplasty

Abstract

Argon laser peripheral iridoplasty involves placement of contraction burns within the iris stroma in the far periphery either with or without a laser goniolens to treat appositional angle closure after a laser peripheral iridotomy (LPI) has been performed to rule out relative pupillary block. The key to successful Argon laser peripheral iridoplasty (ALPI) involves laser settings of low-energy, long-duration, and large spot size causing the peripheral iris to contract toward the “slow” contraction burn, relieving angle closure, thereby facilitating access of aqueous to the iridocorneal angle (Surv Ophthalmol 52:279–288, 2007; Glaucoma – the requisites in ophthalmology, St. Louis, 2000). During laser application, the endpoint is visible shrinkage of the peripheral iris. The power setting should be adjusted until visible stromal contraction is noted. The foot pedal should be fully depressed for the entire duration during laser delivery avoiding premature applications. Deepening of the AC should be noted in the vicinity of the laser burn. A common cause for failure of ALPI is to treat the mid-peripheral iris instead of the far periphery. Approximately six spots are applied in each quadrant treating the entire circumference. Given the low-energy setting, ALPI results in minimal inflammation that can be treated with a short course of topical steroids. Familiarity with gonioscopy fundamentals including indentation is important for diagnosis and pre-laser planning (University of Iowa Health Care Ophthalmology and Visual Sciences, www.gonioscopy.orgg).

Indications

Argon laser peripheral iridoplasty is indicated in patients with appositional angle closure that persists despite a patent iridotomy (Fig. 57.1a, b) due to mechanisms other than relative pupillary block [1]. It can also be used prior to laser peripheral iridotomy (LPI) in the setting of thick irides [2] and increased risk of bleeding due to use of blood thinners [2] or to widen the angle for improved viewing before performing trabeculoplasty [1, 3] (Table 57.1).

Fig. 57.1

Slit lamp photomicrograph showing an eye treated with ALPI. Note the presence of multiple atrophic laser marks in the far iris periphery (a). The patient had plateau iris syndrome with persistence of appositional angle closure despite the presence of a patent LPI noted on retro-illumination (b) – iridoplasty and LPI (Taylor Pannell, CRA, OCT)

Table 57.1 Indications for Argon laser iridoplasty

Essential Steps

• 1. Pre-laser treatment with topical anesthetic, IOP lowering, and pupil constricting drops

• 2. Patient positioning at slit lamp coupled to Argon laser

• 3. Appropriate Argon laser settings of low-energy, long-duration, and large spot size

• 4. Delivery of energy to far peripheral iris with or without a Goldmann 3-mirror laser contact lens

• 5. Observation of visible shrinkage of iris stroma at site of application

• 6. Application of four to six laser burns per quadrant

• 7. Post-laser instillation of IOP lowering medication

• 8. IOP check 30–40 min post-laser to check for IOP spike

Complications

• 1. Post-laser inflammation

• 2. Acute IOP elevation

• 3. Minor discomfort during application of burns

• 4. Corneal endothelial burns [1]

• 5. Ectopic pupil [2]

Template Operative Dictation

Preoperative diagnosis:

Angle closure (OD/OS)

Procedure:

Argon laser peripheral iridoplasty (OD/OS)

Postoperative diagnosis:

Same

Indication:

This ____-year-old (male/female) was diagnosed with appositional angle closure on gonioscopy [4] despite the presence of a patent laser iridotomy.

Description of the procedure:

After discussing risks, benefits, alternatives, and obtaining consent, the (right/left) eye was marked with a marking pen in the examination room. After placing a drop of anesthetic, one drop of __% pilocarpine was instilled to constrict the pupil, along with one drop of apraclonidine to lower the IOP pre-laser. Approximately _15 min later, the patient was transferred to the Argon laser room suite and placed at the slit lamp. Initial laser settings of 200 μm spot size, 0.5 s duration, and 300 mW power were set using the green wavelength.

[Choose one]:

If Goldmann 3-mirror laser contact lens was used – A drop of anesthetic was applied, and the lower lid was pulled and held down. The Goldmann 3-mirror contact lens filled with a coupling gel was gently placed on the eye. The laser beam was directed into the far periphery of the iris through the lens.

If performed without a contact lens – The laser beam was aimed in the far iris periphery.

Approximately four to six spots were applied in the far periphery per quadrant treating the entire iris circumference. Contraction of the iris was observed, and the power was adjusted to achieve this endpoint.

One drop of apraclonidine was instilled at the end of the procedure, and IOP was checked _40 min post-laser to detect any spikes. The patient was advised to use a 1% prednisolone acetate one drop four times a day for _5_ days.

Additional Resource

https://www.youtube.com/watch?v=gC6dfYQ_hxY.