Ophthalmic Surgery, Lasers and Imaging Retina

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Case Report 

Argon Laser Photocystotomy of a Vitreous Cyst

Rajen U. Desai, MD; Norman A. Saffra, MD, FACS

Abstract

Free-floating idiopathic vitreous cysts are rare entities. For symptomatic patients, treatment options include laser photocystotomy or pars plana vitrectomy (PPV) with cyst excision. Historically, size of the cyst impacted treatment approaches. Laser treatments have been used for smaller cysts ranging 3 to 5 mm in diameter. PPV has been utilized for cysts larger than 4 mm. Successful laser photocystotomy has been reported, utilizing both argon and Nd: YAG lasers. Herein, we present a case of successful argon laser photocystotomy of a 7.1 mm diameter vitreous cyst, the largest documented cyst ever treated. Treatment should be individualized based on patient age, ability to cooperate in an office setting, phakic status, status of the posterior hyaloid, cyst morphology, and location. In our case, because of pigment on the anterior cyst surface, and the presence of an attached posterior hyaloid, the argon green laser was used.

Abstract

Free-floating idiopathic vitreous cysts are rare entities. For symptomatic patients, treatment options include laser photocystotomy or pars plana vitrectomy (PPV) with cyst excision. Historically, size of the cyst impacted treatment approaches. Laser treatments have been used for smaller cysts ranging 3 to 5 mm in diameter. PPV has been utilized for cysts larger than 4 mm. Successful laser photocystotomy has been reported, utilizing both argon and Nd: YAG lasers. Herein, we present a case of successful argon laser photocystotomy of a 7.1 mm diameter vitreous cyst, the largest documented cyst ever treated. Treatment should be individualized based on patient age, ability to cooperate in an office setting, phakic status, status of the posterior hyaloid, cyst morphology, and location. In our case, because of pigment on the anterior cyst surface, and the presence of an attached posterior hyaloid, the argon green laser was used.

Argon Laser Photocystotomy of a Vitreous Cyst

From the Division of Ophthalmology, Maimonides Medical Center, Brooklyn, New York.

The authors have no financial or proprietary interest in the materials presented herein.

The authors thank Willie Wood for the figure preparation and Leestyle Rachakonda for references.

Address correspondence to Norman A. Saffra, Director, Division of Ophthalmology, Maimonides Medical Center, 902 49th Street, Brooklyn, NY 11219.

Accepted: July 30, 2009
Posted Online: March 09, 2010

Introduction

Though vitreous cysts are rare, their wide variety—congenital to acquired, clear to pigmented, fixed to free-floating—presents an elusive singular etiology. Orellana et al. suggested an origin from the anterior pigmented tissues of the iris, ciliary body, or pars plana.1 In contrast, Nork and Millecchia suggest an etiology of primitive hyaloid system choristoma.2 Other hypotheses include coloboma cystic growths or vitreous reactions to conditions such as retinitis pigmentosa, sarcoidosis, and hydatid infections.

Management of non-infectious cysts are limited to: observation, laser photocystotomy, and pars plana vitrectomy (PPV) with cyst excision. There have been only four reports on the success of photocystotomy alone for cysts, ranging from 3 to 4 mm in diameter.3–6 We present the largest documented vitreous cyst (7.1 mm in diameter) successfully treated either with laser or surgical intervention. Moreover, we successfully ruptured the cyst, stimulating its involution and disappearance using only the argon green laser.

Case Report

A 46 year-old man complained for two years of a “ball-like floater” blurring the vision in his left eye. He reported 20/20 visual acuity both eyes (OU) earlier. There was no history of eye surgery, trauma, or family history of ophthalmic disease.

Best-corrected visual acuity was 20/20 right eye (OD) with −1.00 sphere and 20/50 left eye (OS) with a plano lens. External examination, confrontational visual fields, ocular motility, pupillary light reflexes, and slit-lamp examination were all within normal limits. Gonioscopy demonstrated the absence of ciliary body mass or lesions OU. Intraocular pressures were 18 and 16 mm Hg, respectively.

Dilated funduscopic examination was within normal limits OD, but revealed a large spherical vitreous cyst OS with pigment on the anterior surface, without evidence of any intra-cyst lesions. The cyst was located in the center of the posterior vitreous cavity, and moved with changes in head and eye position (Fig. 1). There was no posterior vitreous detachment (PVD).

Fundus Photo at Initial Visit of the Free-Floating Vitreous Cyst.

Figure 1. Fundus Photo at Initial Visit of the Free-Floating Vitreous Cyst.

B-scan ultrasound confirmed the presence of a hypo-echoic spherical cyst 7.1 mm in diameter (Fig. 2). Ultrasound biomicroscopy ruled out anomalies of the ciliary body and posterior iris. Serological tests were negative for Toxoplasma gondii, Toxocara species, echinococcosis, and cysticercosis.

B-Scan Ultrasound Demonstrating 7 mm Diameter Free-Floating Vitreous Cyst, with No Surrounding Attachments.

Figure 2. B-Scan Ultrasound Demonstrating 7 mm Diameter Free-Floating Vitreous Cyst, with No Surrounding Attachments.

Three month follow-up revealed an unchanged examination. Risks and benefits of continued observation vs laser photocystotomy vs PPV were discussed with the patient, and he gave informed consent for photocystotomy.

The patient was placed in a seated position in front of a Zeiss 30SL slit-lamp delivery system supplied by an argon green laser. A Volk Area Centralis laser-coated diagnostic/therapeutic contact lens was applied. Laser settings included 350 mW, 0.05 second duration, and 100 μm spot size. In an annual pattern, 34 spots were applied to the anterior pigmented part of the cyst, to create an opening (Fig. 3A). There were no complications to the procedure, or retinal burns. No post operative drops were used.

Fundus Photos (A) Immediately After Argon Laser Treatment, with Burn Spots Indicated by the Arrow, and (B) 2-Weeks After Treatment, with a Cyst Remnant Settled Inferiorly.

Figure 3. Fundus Photos (A) Immediately After Argon Laser Treatment, with Burn Spots Indicated by the Arrow, and (B) 2-Weeks After Treatment, with a Cyst Remnant Settled Inferiorly.

At the 2-week visit, the patient reported a significant improvement in visual. The cyst had substantially decreased in size, with collapsed walls, and was now inferiorly out of the visual axis (Fig. 3B). After three additional weeks, the vitreous was clear of any cyst remnants and the patient was asymptomatic.

Discussion

Long-term observation of vitreous cysts demonstrated a benign clinical course, with no reports of spontaneous rupture or size reduction. Asymptomatic, peripherally located cysts may be observed. However for symptomatic cysts, it is reasonable to inform patients, at presentation, of the risks and benefits of observation, or treatment with either laser photocystotomy or PPV with cyst excision.

Consideration of possible infectious etiologies is crucial, prior to initiating treatment. Laser photocystotomy is contraindicated, as laser-ablated Echinococcal cysts may induce an anaphylactic intraocular reaction.8

Historically, all but one of the cysts ≤ 4 mm were treated with laser whereas cysts > 4 mm were treated with PPV.1–6,9 However, in our opinion, size need not be a significant factor in deciding treatment method, as we were able to laser a 7.1 mm cyst with no persistent remnants. Therefore, once deciding to proceed with treatment, laser photocystotomy should be attempted prior to PPV, based on the risk profile of the respective treatments.

The next choice is deciding either Nd:YAG or argon green laser, both of which have been efficacious in treating vitreous pathology. Both Tsai et al. and Delaney et al. successfully used Nd:YAG for a combined 57 vitreous floaters.10,11 Given their criteria of not applying laser within 2 to 4 mm of the retina or crystalline lens, and that 55 of the eyes had PVDs, their use of Nd:YAG produced no retinal complications.12

However, vitreous floaters are different from vitreous cysts, particularly in regard to PVD and pigment. As such, there may not be a direct parallel from using floater behavior with Nd:YAG. While floaters are often associated with PVDs, vitreous cysts may often have attached posterior hyaloids, and hence, the theoretical risk of deep vitreous use of Nd:YAG include retinal breaks from either induced traction or direct retinal trauma.12–16

Patient cooperation and phakic status may also impact wavelength choice. The Nd:YAG can damage an IOL and even the crystalline lense; indeed, Gupta et al. use of this wavelength produced a posterior lenticular opacity in an 8-year-old patient.6,14

There are only three reported excised cysts, all of which were pigmented, with histology comprising pigment epithelium and melanosomes.1,2,9 These pigmented structures highly absorb the argon green 514.5 nm wavelength laser, permitting minimal energy to penetrate and be absorbed by adjacent structures. The presence of pigment on the cyst surface may optimize the choice of the argon green wavelength. Furthermore, when the posterior hyaloid is attached, the coagulative properties of argon laser produce less risk of retinal breaks, though not necessarily retinal burns, and make it a better wavelength choice in this scenario.

Due to the rarity of vitreous cysts, there have been no studies evaluating, in a randomized or comparative fashion, comparisons of different laser wavelengths. That said, we reviewed the four previous reports of photocystotomies, all of pigmented cysts, to compare laser settings (Table).2–5 Though Woolf and Swann reported photocystotomy of a 3 mm pigmented cyst, their publication did not include laser settings.6 If the physician, patient, and vitreous characteristics align with argon as the preferred laser wavelength, contact lens choice and laser settings (ie spot size, energy, duration) should be optimized for the particular cyst targeted. We believe that the argon laser settings we used may be a starting point to achieve cyst rupture with the least amount of energy applied to the eye.

Summary of Laser Settings in Vitreous Cyst Photocystotomy

Table: Summary of Laser Settings in Vitreous Cyst Photocystotomy

In summary, there are successful reports of vitreous cyst treatment, using laser photocystotomy as well as PPV. We recommend that treatment consideration be individualized based on: patient age, ability to cooperate in an office setting, phakic status, and cyst location (and not cyst size alone), posterior hyaloid status, and pigment status. Due to the features of the vitreous cyst in our case, the argon green laser was the preferable wavelength for successful photocystotomy.

References

  1. Orellana J, O’Malley RE, McPherson AR, Font RL. Pigmented free-floating vitreous cysts in two young adults. Ophthalmology. 1985;92:297–302.
  2. Nork TM, Millecchia LL. Treatment and histopathology of a congenital vitreous cyst. Ophthalmology. 1998;105:825–830. doi:10.1016/S0161-6420(98)95020-5 [CrossRef]
  3. Awan KJ. Biomicroscopy and argon laser photocystotomy of free floating vitreous cyst. Ophthalmology. 1985;92:1710–1711.
  4. Ruby AJ, Jampol LM. Nd:YAG treatment of a posterior vitreous cyst. Am J Ophthalmol. 1990;110:428–429.
  5. Gupta R, Pannu BK, Bhargav S, Narang S, Sood S. Nd:YAG laser photocystotomy of a free-floating pigmented anterior vitreous cyst. Ophthalmic Surg Lasers Imaging. 2003;34:203–205
  6. Woolf P, Swann PG. Free-floating vitreous cysts. Clin Exp Optom. 1999;82:17–19.
  7. Steinmetz RL, Straatsma BR, Rubin ML. Posterior vitreous cyst. Am J Ophthalmol. 1990;109:295–297.
  8. Nahri GE. A simplified technique for removal of orbital hydatid cysts. Br J Ophthalmol. 1991:75;743–745. doi:10.1136/bjo.75.12.743 [CrossRef]
  9. Lira RPC, Jungmann P, de Moraes LFL, Silveira APT. Clinical features, histopathological analysis and surgical treatment of a free floating vitreous cyst: a case report. Arq Bras Oftalmol. 2006;69:753–755 doi:10.1590/S0004-27492006000500026 [CrossRef]
  10. Delaney YM, Oyinloye A, Benjamin L. Nd:YAG vitreolysis and pars plana vitrectomy: surgical treatment for vitreous floaters. Eye. 2002;16:21–26. doi:10.1038/sj.eye.6700026 [CrossRef]
  11. Tsai WF, Chen YC, Su CY. Treatment of vitreous floaters with neodymium YAG laser. Br J Ophthalmol. 1993;77:485–488. doi:10.1136/bjo.77.8.485 [CrossRef]
  12. Bonner RF, Meyers SM, Gaasterland DE. Threshold for retinal damage associated with the use of high-power neodymium-YAG lasers in the vitreous. Am J Ophthalmol. 1983;96:153–159.
  13. Murakami K, Jalkh AE, Avila MP, et al. Vitreous floaters. Ophthalmology. 1983;90:1271–1276.
  14. Lyle WM, Cullen AP, Charman WN. Role of lasers in eye care. Optometry and Vis Sci. 1993:70;136–151. doi:10.1097/00006324-199302000-00010 [CrossRef]
  15. Charles S. Vitreoretinal complications of YAG laser capsulotomy. Ophthalmol Clin North Am. 2001;14:705–710. doi:10.1016/S0896-1549(05)70269-8 [CrossRef]
  16. Little HL, Jack RL and . Q-switched neodymium: YAG laser surgery of the vitreous. Graefes Arch Clin Exp Ophthalmol. 1986;224:240–246. doi:10.1007/BF02143063 [CrossRef]

Summary of Laser Settings in Vitreous Cyst Photocystotomy

ReferenceCyst Diameter (mm)WavelengthSpot Size (μm)Duration (second)Energy
Awan33Argon green2000.1500 mW
Ruby & Jampol43.7Nd:YAG, fundamental mode, Q-switched7Unspecified2.4 to 3.2 mJ
Nork and Millecchia25Argon green50Unspecified300 to 560 mW
Gupta et al.54Nd:YAG, fundamental mode, Q-switched7Unspecified2.4 to 3.4 mJ
Present study7.1Argon green1000.05350 mW
Authors

From the Division of Ophthalmology, Maimonides Medical Center, Brooklyn, New York.

The authors have no financial or proprietary interest in the materials presented herein.

Address correspondence to Norman A. Saffra, Director, Division of Ophthalmology, Maimonides Medical Center, 902 49th Street, Brooklyn, NY 11219.

10.3928/15428877-20100215-79

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