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Arch Ophthalmol. 2002;120:1393-1394.

Diode laser cyclophotocoagulation is increasingly used in the treatment of refractory glaucoma^1-2 due to its simplicity of use and effectiveness. Complications include iritis, hyphema, pupillary distortion,³ staphyloma formation,³ scleral perforation,⁴ and phthisis bulbi.¹ We report a case of lens subluxation following transscleral cyclodiode laser treatment.

Report of a Case
A 61-year-old woman with hypermetropia came to the eye casualty with a 3-week history of reduced vision (hand movements) in her left eye due to neovascular glaucoma secondary to central retinal vein occlusion. Her fellow eye was normal. She underwent argon laser panretinal photocoagulation twice, with no regression of rubeosis. Because the cornea showed signs of early decompensation due to persistently raised intraocular pressure (IOP), transscleral cyclodiode laser was performed. The standard probe (quartz G-probe attachment of the Iris medical-Oculight SLx diode laser; Iris Medical Instruments Inc, Mountain View, Calif) was used for 15 applications of 1.5 seconds' duration and 2 W each (popping noise was noted) along the inferior half of the ciliary body. The IOP remained raised and laser treatment was repeated with settings of 2.5 to 3 W, each of 1.5 seconds' duration, to a total of 2 treatments superiorly and 2 inferiorly (80 laser burns) during a 6-month period. No blood or pigment was noted on the probe during any treatments. There was no history of ocular trauma at any time.

Following the fourth application, the IOP was well controlled without treatment and the cornea was clear. Seven weeks after the last laser treatment, the patient was found to have a 180° superior zonular dehiscence and lens subluxation inferonasally (Figure 1), with vitreous prolapse into the anterior chamber. The limbal sclera was then noted to be thinned superiorly and inferonasally. There were no signs of phacolytic glaucoma or persistent uveitis.

View larger version (36K): [in this window] [in a new window] Subluxation of the crystalline lens inferonasally.

Comment
Transscleral diode cyclophotocoagulation is an effective and popular method of management of glaucoma that is unresponsive to conventional treatment. Its IOP-lowering effect is due to coagulation necrosis of the ciliary epithelium. Laser treatment can be performed in a contact or noncontact mode but the former has better scleral transmission and thus uses less energy.¹ Owing to the rarity of severe adverse effects, repeated use of this treatment is common.

Staphyloma formation,³ scleral perforation,⁴ and phthisis bulbi caused by scarring of the angle structures³ are recognized complications but lens subluxation following contact cyclodiode has not been reported to our knowledge. Our patient did not have preexisting risk factors, ie, zonule weakness and scleral thinning. Laser treatment was repeated to reduce IOP and prevent bullous keratopathy. Zonular dehiscence and lens subluxation presumably occurred because of laser-induced damage of the ciliary body and zonules.

At the time of this report, since our patient has no useful vision in this eye, isolated lens subluxation has not caused her significant problems. However, diode laser is used to treat glaucoma in eyes with good vision. Where repeated treatments are necessary, the patient should be warned of the risk of lens subluxation and secondary complications, such as pupil block, corneal touch, phacolytic glaucoma, and uveitis. Avoiding contact laser in patients with zonular abnormality and scleral thinning has been recommended.⁴ If absolutely necessary, lower energy should be used and care should be taken to avoid pathologic areas.

AUTHOR INFORMATION

Veena J. Rao, FRCS, DO; Margaret Dayan, FRCOphth
Newcastle-upon-Tyne, England

Corresponding author and reprints: Veena J. Rao, FRCS, DO, Department of Ophthalmology, Royal Victoria Infirmary, Newcastle-upon-Tyne, England, NE1 4LP (e-mail: rao_vj{at}hotmail.com).

REFERENCES
1. Vogel A, Dlugos C, Nuffer R, et al. Optical properties of human sclera, and their consequences for trans-scleral laser applications. Lasers Surg Med. 1991;11:331-334. ISI | PUBMED 2. Gaasterland DE, Pollack IP. Initial experience with a new method of laser trans-scleral cyclo-photocoagulation for ciliary ablation in severe glaucoma. Trans Am Ophthalmol Soc. 1992;90:225-246. PUBMED 3. Bhola RM, Prasad S, McCormick AG, et al. Pupillary distortion and staphyloma following trans-scleral contact diode laser photocoagulation: a clinicopathological study of three patients. Eye. 2001;15:453-457. PUBMED 4. Sabri K, Vernon SA. Scleral perforation following trans-scleral cyclodiode. Br J Ophthalmol. 1999;83:502-503.