Nd-YAG Laser Capsulotomy

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Neodymium-doped yttrium aluminum garnet (Nd:YAG) laser capsulotomy is a relatively noninvasive procedure that is used in the treatment of posterior capsular opacification. Posterior capsular opacification is a common long-term complication of cataract surgery that causes decreased vision, glare, and other symptoms similar to that of the original cataract. ^[1] Posterior capsular opacification is caused by a proliferation of lens epithelial cells, which causes fibrotic changes and wrinkling of the posterior capsule. Its reported frequency ranges from 8.7% to 33.4%. ^{[2, 3, 4, 5]}

Laser capsulotomy uses a quick-pulsed Nd:YAG laser to apply a series of focal ablations in the posterior capsule and create a small circular opening in the visual axis. Yttrium aluminum garnet (YAG) capsulotomies were developed in the early 1980s by Drs. Aron-Rosa and Fankhauser. Aron-Rosa had a strong background in physics prior to becoming an ophthalmologist and an especially keen interest in the early ruby lasers of the time. She found that the pulses were too slow for her intention, which was to determine a laser beam wavelength that would not disrupt the integrity or temperature of surrounding tissue within 100 μm of the target.

By multiplying the Nd:YAG frequency, Dr. Aron-Rosa was able to use the laser in various wavelengths. She applied for a patent in 1978 and began her clinical trials in October of that year. Over the next 4 years, she performed the procedure in 5000 eyes. ^[6] In November 1980, Fankhauser performed his first YAG capsulotomy. ^[7] The procedure caught on quickly because the alternative was surgical dissection of the posterior capsule, which is a more inherently invasive procedure. With the older intraocular lenses, opacification rates could be as high as 50%. ^[8] As the intraocular lens technology has improved, the rates of opacification have decreased greatly.

Indications for Nd:YAG laser capsulotomy include the following:

Interference with daily activities

Decreased vision (patients with multifocal intraocular lenses may be particularly sensitive to even small posterior capsular changes)

Increased glare

Difficulty visualizing the fundus

Lens tilt and Z syndrome associated with hinged accommodating lenses such as the Crystalens and Trulign toric lens (lens tilt occurs when one haptic is planar and the other haptic is vaulted anteriorly or posteriorly; Z syndrome occurs when one haptic is vaulted anteriorly and the other is vaulted posteriorly)

In cases of a small anterior capsulorrhexis, capsular phimosis or capsular contraction can occur. This excessive scarring anterior to the intraocular lens can compromise vision. It can be alleviated by radial anterior capsulotomies, which can be achieved with the Nd:YAG laser. ^[9]

Relative contraindications for Nd:YAG capsulotomies include the following:

Corneal scarring or edema that prevents a clear view during the procedure

Placement of a glass intraocular lens during cataract surgery

Presence of iritis in the eye

Macular edema in the retina

Use caution in the following cases:

Patients with a history of retinal tears or detachments ^[10]

Patients in the immediate postoperative period because the intraocular lens may not be adequately scarred into place

Patients with glaucoma, who may have an intraocular pressure spike from the inflammation or postoperative steroid response ^[11]

An Abraham YAG capsulotomy lens is used in conjunction with a coupling agent, such as 2% or 2.5% hydroxypropyl methylcellulose, to form a seal on the eye. In addition to helping keep the eye open, the lens has a 10.0-mm helium-neon YAG-coated plano-convex 1.8× magnification button positioned at the center of the lens, which focuses the beam spot size on the posterior capsule.

Anesthesia

Topical anesthesia can be used to perform Nd:YAG capsulotomies without any significant discomfort for the patient.

Positioning

Nd:YAG capsulotomy is performed at a slit lamp equipped with a YAG laser, while the patient is in a seated position. ^[12]

Patients are usually put on topical steroids for inflammation at the discretion of the surgeon.

Patients are usually brought back at 1 week postoperatively for a manifest refraction and to assess the intraocular pressure and inflammation. A dilated fundus examination can be performed to rule out macular edema or tears in symptomatic patients, but it is not necessary. A postoperative examination after 1 month can be performed, but that is also optional.

Retreatment is not necessary unless the YAG did not ablate the posterior capsule fully or if it was cut short because of excessive energy.

Complications may include the following:

Transient intraocular pressure elevation

Iritis

Retinal tears and detachments

Macular edema

Corneal edema

Intraocular lens dislocation into the vitreous

Pitting of the intraocular lens

The incidence of intraocular pressure elevations are significantly reduced when patients are pretreated with apraclonidine. Intraocular pressure can be checked 30-60 minutes postoperatively, although that is surgeon dependent.

Iritis can be present after the capsulotomy, but it is usually self-limited. It can be treated with a weeklong course of topical steroids (1% prednisone acetate or 0.5% loteprednol, 4 times daily).

Patients are usually pretreated with dilating drops, such as tropicamide 1.0%, phenylephrine 2.5%, or cyclopentolate 1-2%, as the posterior capsular opacity needs to be visualized through a dilated pupil. To prevent a transient postoperative intraocular pressure spike, a drop of apraclonidine 0.5% can also be given.

The laser should be set somewhere from 1-3 mJ and can be Q-switched, mode locked, or both. A Q-switched laser produces a series of single pulses that each last 12-20 nanoseconds, whereas a mode-locked laser produces a train of pulses that each last 25-30 picoseconds. These settings help deliver higher power.

Because the Nd:YAG laser is actually invisible, a helium-neon laser is actually used as a focusing device. ^[13] The laser can be focused slightly posterior to the lens to avoid pitting of the lens. Silicone lenses have been found to be more easily damaged than acrylic lenses. Polymethylmethacrylate lenses have been found to be the most resilient.

Methods of laser treatment are surgeon dependent and may depend on the density of the opacity. A cross-pattern with both axes beginning in the periphery has been advocated by many physicians to decrease the risk of central pitting. ^[14] A circular laser can be applied afterwards. Other physicians recommend avoiding a circular laser in favor of firing on fixed stress lines. The capsule should reflect out of the visual axis on its own. ^[15] Another method is to make a 3-mm inverted U-shape, such that the capsule reflects inferiorly. It is claimed that the flap stays out of the visual axis and cuts down on postoperative floaters. ^[16]

Small capsulotomies (2-3 mm) have been found to be equally as effective as large capsulotomies (5-6 mm), although larger capsulotomies may be more helpful for those with symptomatic glare. ^[17]

A host of methods to treat lens tilt and Z syndrome with Nd:YAG laser have been postulated. Treatment typically centers on trying to relieve tension behind the anteriorly vaulted haptic by performing a small oval capsulotomy between the hinge and the insertion of the hinge loops, taking care to lyse any fibrotic bands that are present. It is important to avoid extending the capsulotomy past the edge of the optic to avoid anterior migration of the vitreous. If this is insufficient, a small noncontiguous central capsulotomy can be done. If this is also insufficient, a small oval capsulotomy behind the posteriorly vaulted haptic can also be performed. ^[18]

Aslam TM, Patton N. Methods of assessment of patients for Nd:YAG laser capsulotomy that correlate with final visual improvement. BMC Ophthalmol. 2004 Sep 23. 4:13. [Medline]. [Full Text].

Oner FH, Gunenc U, Ferliel ST. Posterior capsule opacification after phacoemulsification: foldable acrylic versus poly(methyl methacrylate) intraocular lenses. J Cataract Refract Surg. 2000 May. 26(5):722-6. [Medline].

Knorz MC, Soltau JB, Seiberth V, Lorger C. Incidence of posterior capsule opacification after extracapsular cataract extraction in diabetic patients. Metab Pediatr Syst Ophthalmol. 1991. 14(3-4):57-8. [Medline].

Awan MT, Khan MA, Al-Khairy S, Malik S. Improvement of visual acuity in diabetic and nondiabetic patients after Nd:YAG laser capsulotomy. Clin Ophthalmol. 2013. 7:2011-7. [Medline]. [Full Text].

Ari S, Cingü AK, Sahin A, Çinar Y, Çaça I. The effects of Nd:YAG laser posterior capsulotomy on macular thickness, intraocular pressure, and visual acuity. Ophthalmic Surg Lasers Imaging. 2012 Sep-Oct. 43(5):395-400. [Medline].

Aron-Rosa D, Aron JJ, Griesemann M, Thyzel R. Use of the neodymium-YAG laser to open the posterior capsule after lens implant surgery: a preliminary report. J Am Intraocul Implant Soc. 1980 Oct. 6(4):352-4. [Medline].

Bath PE, Fankhauser F. Long-term results of Nd:YAG laser posterior capsulotomy with the Swiss laser. J Cataract Refract Surg. 1986 Mar. 12(2):150-3. [Medline].

Apple DJ, Peng Q, Visessook N, Werner L, Pandey SK, Escobar-Gomez M. Eradication of posterior capsule opacification: documentation of a marked decrease in Nd:YAG laser posterior capsulotomy rates noted in an analysis of 5416 pseudophakic human eyes obtained postmortem. Ophthalmology. 2001 Mar. 108(3):505-18. [Medline].

Deokule SP, Mukherjee SS, Chew CK. Neodymium:YAG laser anterior capsulotomy for capsular contraction syndrome. Ophthalmic Surg Lasers Imaging. 2006 Mar-Apr. 37(2):99-105. [Medline].

Fan DS, Lam DS, Li KK. Retinal complications after cataract extraction in patients with high myopia. Ophthalmology. 1999 Apr. 106(4):688-91; discussion 691-2. [Medline].

Barnes EA, Murdoch IE, Subramaniam S, Cahill A, Kehoe B, Behrend M. Neodymium:yttrium-aluminum-garnet capsulotomy and intraocular pressure in pseudophakic patients with glaucoma. Ophthalmology. 2004 Jul. 111(7):1393-7. [Medline].

Longmuir S, Titler S, Johnson T, Kitzmann A. Nd:YAG laser capsulotomy under general anesthesia in the sitting position. J AAPOS. 2013 Aug. 17(4):417-9. [Medline].

Nirankari VS, Richards RD. Clinical study of the neodymium: yttrium-aluminum-garnet (Nd: YAG) laser. Indian J Ophthalmol. 1984 Sep-Oct. 32(5):421-3. [Medline].

Levy JH, Pisacano AM. Comparison of techniques and clinical results of YAG laser capsulectomy with two Q-switched units. J Am Intraocul Implant Soc. 1985 Mar. 11(2):131-3. [Medline].

Murrill CA, Stanfield DL, Van Brocklin MD. Capsulotomy. Optom Clin. 1995. 4(4):69-83. [Medline].

Zeki SM. Inverted U’ strategy for short pulsed laser posterior capsulotomy. Acta Ophthalmol Scand. 1999 Oct. 77(5):575-7. [Medline].

Goble RR, O’Brart DP, Lohmann CP, Fitzke F, Marshall J. The role of light scatter in the degradation of visual performance before and after Nd:YAG capsulotomy. Eye (Lond). 1994. 8 ( Pt 5):530-4. [Medline].

Friedman NJ. Pearls for the Diagnosis and Treatment of Crystalens Syndromes. OphthalmologyWeb. Available at http://www.ophthalmologyweb.com/Featured-Articles/119545-Pearls-for-the-Diagnosis-and-Treatement-of-Crystalens-Syndromes/. Accessed: 5/1/15.

Harish Raja Mount Sinai School of Medicine of New York University

Disclosure: Nothing to disclose.

Deepak Raja, MD Ophthalmologist, Orlando Eye Institute, LLC; Assistant Professor of Ophthalmology, University of Central Florida College of Medicine

Deepak Raja, MD is a member of the following medical societies: American Academy of Ophthalmology, American Society of Cataract and Refractive Surgery, Cornea Society

Disclosure: Nothing to disclose.

Hampton Roy, Sr, MD Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences

Hampton Roy, Sr, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, Pan-American Association of Ophthalmology

Disclosure: Nothing to disclose.

Nd-YAG Laser Capsulotomy

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