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Morning Rounds
The Rifleman Who Changed His View
By Sean Paul, MD, and Reagan H. Bradford, MD
Edited by Thomas A. Oetting, MD
 
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Christopher McCurley* has spent his adult life touring the globe as an active duty soldier. In fact, the 33-year-old is known as the top sharpshooter in his battalion. However, on one of his recent combat missions, he noticed that the vision in his left eye had begun to fluctuate so much that he needed to begin using his right eye as his aiming eye. After finishing tours of duty in South America and the Middle East and consulting with a military eye specialist, he returned home to Oklahoma for further medical evaluation with us. 


We Get a Look

When we saw Mr. McCurley, he told us that he had “pretty good vision” but that he had recently begun having trouble focusing and felt that his peripheral vision had worsened. He reported that he had noticed intermittent vision blockage in his left eye and subsequently changed his aiming eye because of this problem. He denied having any other history of eye problems. He also acknowledged that, even though he noticed the visual changes only recently, they might have been developing over the course of a few months. He denied experiencing any trauma to this eye or having any recent history of infection.

Mr. McCurley reported that he takes blood pressure medication but has no other chronic medical problems. He had no history of previous surgeries, and his social and family histories were unremarkable. His review of systems was negative other than the chief complaint.

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What We Found

Mr. McCurley’s BCVA was 20/15 in both eyes, with no afferent pupillary defect. His IOP was 14 mmHg in the right eye and 15 mmHg in the left. On confrontation visual field testing, the right eye was full to counting fingers. Initially, the left eye was full to counting fingers, but on retesting, it showed inconsistent results. This inconsistency was confirmed on repeat testing.

The anterior segment examination of both eyes was unremarkable. On the dilated fundus exam, the right eye was unremarkable, while the left eye showed a spherical, cystic structure in the mid-vitreous that appeared mostly clear with scattered pigmentation. There was no inflammation in the vitreous.

The retina appeared unremarkable, as did the optic nerve, macula and vessels. The spherical object obscured the inferior periphery, but when Mr. McCurley changed his head position, the object moved, and there was no evidence of pathology in the periphery. B-scan ultrasonography showed a spherical object suspended in the vitreous; the object measured 4 mm in diameter and moved with the globe position.

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Differential Diagnosis

Mr. McCurley presented with an isolated, unilateral vitreous cyst without any other symptoms or signs.

Our first challenge was to determine whether the cyst was infectious or noninfectious in nature. Infectious vitreous cysts may result from cysticercosis, echinococcosis, toxocariasis or toxoplasmosis. Noninfectious cysts may be related to remnants of the hyaloid system or elements of the embryonic vitreous. Alternatively, they may be iris cysts that have migrated into the vitreous, or they may be caused by trauma or a foreign body. Other causes of vitreous cysts, found only as single case reports in the literature, include uveitis-related cysts and cysts seen after old retinal detachments or retinoschisis.

Given Mr. McCurley’s impressive travel history, we naturally first thought of infectious etiologies. However, he did not have a history of exposure to wild animals or a track record of eating questionable foods during his travels. Moreover, he did not exhibit any signs or symptoms of systemic infection, and the results of a recent complete blood count were within normal limits. After we discussed the possibility of a parasitic etiology with him, we also discussed obtaining an IgE level and having him undergo brain imaging. However, he declined additional testing.

Mr. McCurley denied having any history of trauma, and he had no evidence of pathology at the iris. Moreover, he did not have a history of a retinal detachment or retinoschisis. He did mention that his vision might have been affected intermittently during his childhood, although it had not bothered him at that time.

Based on the cyst’s clear appearance with light pigmentation and the negative review of systems, we made a diagnosis of a noninfectious vitreous cyst. We believe that it either is related to hyaloid remnants or is an iris cyst that has migrated to the vitreous.

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What’s Your Diagnosis?

(1) On the fundus exam, the retina of the left eye was normal with some obscuration. (2) There was a spherical structure in the vitreous, but no inflammation.
CRITICAL CLUE. (3) B-scan ultrasound of the left eye.

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Treatment Options

The first description of a vitreous cyst was offered by J. O. Tansley, MD, in 1899. “The irregularly spherical object, with small indentations, somewhat resembled a potato ... its floating body was spheroidal, of about the diameter of the optic disc ... it had no attachments with any other part of the eye and the object would rotate in varying directions and moved in a balloon-like manner.”1

Since Dr. Tansley’s initial discovery, only 60 case reports describing the appearance and treatment of this entity have been published. Given the condition’s rarity, treatment presents some interesting challenges.

Primary management of pigmented, noninfectious vitreous cysts includes observation for asymptomatic patients. For symptomatic patients, laser photocystotomy and pars plana vitrectomy (PPV) with cyst excision have been advocated.

Laser. Laser photocystotomy has been used for cysts ranging from 3 mm to 5 mm in diameter.2 Although both Nd:YAG and argon laser treatments have been used successfully, there have been too few cases reported to date to draw meaningful conclusions.

Choice of laser treatment should be individualized based on patient age, lens status, ability to cooperate, posterior hyaloid status and etiology. For example, the Nd:YAG laser can damage an IOL. Pigmented vitreous cysts absorb the argon green wavelength laser. Furthermore, when the posterior hyaloid is attached, the coagulative properties of argon laser may produce less risk of retinal breaks than the disruptive concussion of the YAG laser, making it a better wavelength choice in this scenario.3

Pars plana vitrectomy. PPV has been used for cysts larger than 4 mm and for those with infectious etiologies. To date, there are only three case reports of pigmented cysts that have been removed using PPV. As with laser photocystotomy, so few cases have been reported that small case series and case reports provide most of the data on treatment options.

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Back to Our Patient

Mr. McCurley declined to undergo any laser or surgical treatment for his noninfectious cyst. He had excellent visual acuity and no longer considered the decrease in peripheral vision to be problematic, as he had already adapted to it by switching his aiming eye.

We agreed that the best course of action at this time was to continue to observe the cyst. We offered the option of laser photocystotomy in the event that he felt the cyst was growing or becoming more bothersome.
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1 Tansley, J. O. Trans Am Ophthalmol Soc 1899;8:507–509.
2 Awan, K. J. Ophthalmology 1985;92(12):1710–1711. 
3 Desai, R. U. and N. A. Saffra. Ophthalmic Surg Lasers Imaging 2010;doi:10.3928/15428877-20100215-79.
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* Patient name is fictitious.
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Dr. Paul is a resident in ophthalmology and Dr. Bradford is a vitreoretinal surgeon; both are at Dean McGee Eye Institute in Oklahoma City. This paper is supported in part by an unrestricted grant from Research to Prevent Blindness to the Department of Ophthalmology at the University of Oklahoma.

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