Neodymium:Yttrium-Aluminum-Garnet Laser Applications in the Cataract Patient

Key Points

Posterior capsular opacification is very common after cataract extraction. Nd:YAG laser capsulotomy is the treatment of choice.
Nd:YAG laser can also be used to perform laser peripheral iridotomy and anterior hyaloid vitreolysis to address pupillary block glaucoma.
For patients with vitreous strands associated with cystoid macular edema after cataract extraction, Nd:YAG laser vitreolysis may be helpful.

Introduction

The neodymium:yttrium-aluminum-garnet (Nd:YAG) laser is a short, high-power pulse that generates ionization and plasma formation, causing shock and acoustic waves-that disrupt intraocular structures. This chapter focuses on the most common applications of Nd:YAG laser in the postcataract extraction patient.

Procedure Specifics

An explanation of the procedure and informed consent should be obtained before using the Nd:YAG laser. Ocular Nd:YAG laser procedures are contraindicated if significant corneal scarring, edema, or irregularities preclude adequate visualization of the target aiming beam or degrade the Nd:YAG laser beam optics. Patients who cannot fixate adequately are not ideal candidates because of the threat of inadvertent damage to adjacent intraocular structures. Children who can tolerate a slit lamp exam may be good candidates, but sedation may be needed.

Additional relative contraindications to Nd:YAG posterior capsulotomy include patients with a glass intraocular lens (IOL), known or suspected cystoid macular edema (CME), active inflammation, or a high risk for retinal detachment. Nd:YAG laser peripheral iridotomy (LPI) is relatively contraindicated in patients with active uveitis or very shallow anterior chambers. For Nd:YAG vitreolysis, patients should understand that the procedure often requires more than one session.

Nd:Yag Laser Capsulotomies

Posterior Capsule Opacification (PCO)

Fibrotic PCO may present as broad wrinkles that are rarely visually significant or as fine wrinkles that cause marked optical disturbance ( Fig. 54.1 ). PCO can also appear as small Elschnig pearls and bladder cells ( Fig. 54.2 ).

Fig. 54.1, (A) Broad wrinkles of the clear posterior capsule ( arrow ) are seen on red reflex, with numerous small epithelial pearls. (B) Fine wrinkles in the posterior capsule are evident on red reflex ( arrowheads ). These wrinkles alone can be visually disturbing and can reduce acuity by several lines or cause Maddox rod light streaks. (C) and (D), Posterior capsule opacification viewed directly via slit lamp and indirectly via red reflex view, respectively.

Fig. 54.2, Red reflex view shows formation of multiple small epithelial pearls after anterior epithelial cells migrate centrally from peripheral areas of apposition of anterior capsular flaps to the posterior capsule.

Anterior Capsule Contracture

After cataract surgery, the remaining anterior capsule can contract, opacify the visual axis, and even rupture zonular support ( Fig. 54.3 ). Depending on the severity of contracture, early Nd:YAG laser anterior capsulotomy can improve visually significant capsular contraction.

Fig. 54.3, (A) Contracture of the anterior capsule inferiorly has nearly occluded the optical zone. (B) Dilated view of same eye: Nd:YAG laser cutting of the inferior capsule adhesion will restore an adequate visual axis. (C) Symmetric contracture of the anterior capsulorrhexis leaves an inadequate visual axis. (D) Photodisruption of the anterior capsulotomy edge restores an adequate visual axis.

Negative Dysphotopsia

Negative dysphotopsia describes the perception of a crescentic temporal shadow in the visual field. Although the cause of negative dysphotopsia is debated, the interface between the nasal anterior capsule and the anterior IOL surface is thought to be a contributing factor. Nd:YAG laser anterior nasal capsulectomy may be helpful in some cases.

Considerations

Postcataract Extraction Timing of Nd:YAG Posterior Capsulotomy

Ample time should be given postoperatively for the capsule to shrink tightly around the IOL and stabilize it, especially when the capsulotomy opening is larger than the optic. Early Nd:YAG posterior capsulotomy with an unstable IOL poses the risk for IOL movement and vitreous prolapse.

For patients with a history of uveitis, Nd:YAG posterior capsulotomy may be delayed until disease is quiescent for 3 months and may be supplemented by preoperative and postoperative courses of steroids.

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