Pathological Findings of Synchysis Scintillans Secondary to Familial Exudative Vitreoretinopathy With Chronic Exudative Retinal Detachment

Abstract

Purpose:

We describe a unique case of synchysis scintillans in a 23-year-old woman with a history of chronic exudative retinal detachment in the setting of familial exudative vitreoretinopathy.

Methods:

Fundus and slit-lamp photographs were obtained at presentation, and pathological studies were performed on the enucleated specimen to confirm the diagnosis.

Results:

Synchysis scintillans is a degenerative condition of cholesterol deposition that affects severely damaged eyes, often as a result of chronic vitreous hemorrhage or retinal detachment. In this case, synchysis scintillans presented as crystals in the anterior chamber in the setting of a chronic retinal detachment. After enucleation, there were noted to be cholesterol slits on pathological correlation, confirming the diagnosis.

Conclusions:

This case demonstrates the importance of clinical pathological correlation in the diagnosis of synchysis scintillans migrating into the anterior chamber.

Introduction

Synchysis scintillans, or cholesterolosis bulbi, is a degenerative condition of the eye that is characterized by accumulation of cholesterol crystals within the vitreous cavity. ¹ It often follows a long-standing intravitreal hemorrhage or retinal detachment, with the crystals possibly gaining access to the anterior chamber. The authors present a unique case of synchysis scintillans following a chronic retinal detachment associated with familial exudative vitreoretinopathy (FEVR), in which the cholesterol crystals migrated into the anterior chamber with subsequent pathological correlation.

Methods

A 23-year-old woman presented with 2 weeks of sudden photophobia and pain in the right eye. The patient had a history of untreated FEVR, which was monitored with annual fluorescein angiography, with a baseline visual acuity of hand motions OD and 20/20 OS. There was a long-standing total retinal detachment of the right eye with exudation, and fluorescein angiography 2 years prior showed peripheral ischemia with inferior leakage (Figure 1, A and B). On presentation, visual acuity in the right eye was decreased to light perception OD, and intraocular pressure was 18 mm Hg OD and 19 mm Hg OS.

Figure 1.

(A) Fundus photograph displays chronic total retinal detachment with associated exudation. (B) Fluorescein angiography shows peripheral ischemia and inferior leakage. (C) Slit-lamp photograph of the eye exhibits endothelial crystalline plaque and anterior chamber filled with crystalline material. (D) B-scan ultrasonography of the right eye highlights vitreous opacities and extensive retinal detachment.

Slit-lamp examination revealed conjunctival injection and a white corneal endothelial crystalline plaque, along with white crystalline material filling the anterior chamber (Figure 1C). The lens capsule appeared to be intact with few posterior synechiae, and dilated fundus examination revealed a hazy view to the posterior segment. B-scan ultrasonography of the right eye showed vitreous opacities with extensive retinal detachment in all quadrants (Figure 1D). The slit-lamp and dilated fundus examinations of the left eye were unremarkable.

Given the poor visual prognosis of the right eye and the desire to relieve discomfort and achieve optimal cosmesis, the decision was made to enucleate the eye. Pathology of the enucleated globe revealed cholesterol clefts that are characteristic of synchysis scintillans located in the anterior chamber and in the vitreous cavity (Figure 2, A-C).

Figure 2.

(A) Gross enucleated specimen of an eye exhibits refractile crystalline material in the anterior chamber. (B) Anterior chamber cholesterol clefts with a focus of surrounding histiocytes are shown. (C) Cholesterol clefts in the vitreous cavity are found with surrounding foreign-body inflammation composed of histiocytes.

Results

Typically, synchysis scintillans forms as a result of chronic vitreous hemorrhage and is believed to occur from breakdown of intraocular red blood cells that then crystallize. ² However, in this case given the absence of vitreous hemorrhage, the etiology of the synchysis scintillans was likely from the chronic retinal detachment with exudation as a complication of FEVR, in which cholesterol deposits leaked into the vitreous cavity and anterior chamber. ³ Synchysis scintillans has been described as not being clinically visible in the vitreous cavity given that there is usually a poor view with concurrent cataract, pupillary membranes, or updrawn pupils. ⁴ Diffusion of crystals into the anterior chamber is usually facilitated by aphakia or lens subluxation, but in this case the patient had an intact lens but was noted to often sleep on her stomach, thus facilitating the movement of crystals anteriorly by gravitational effect. ⁵

Synchysis scintillans can present as a pseudohypopyon, mimicking phacolysis. ⁶ Although it has been reported that cholesterol deposits can originate from exudative lens material, this case was not consistent with phacolysis, and pathological tests confirmed an intact lens capsule. ⁷ Treatment of synchysis scintillans is limited and enucleation is often performed; this management was chosen given the low visual potential for the involved eye and poor cosmesis.

The pathological specimen exhibited cholesterol clefts in the anterior chamber as well as in the vitreous cavity, characteristic of synchysis scintillans (Figure 2, B and C) that occurs when the lipid eliminated by tissue processing leaves empty spaces that do not stain. Cholesterol clefts of synchysis scintillans have been described on histopathology by Eagle and Yanoff ⁵ as: (1) free crystals in the vitreous or aqueous, (2) typical cholesterol clefts surrounded by a foreign-body inflammatory reaction composed of histiocytes and giant cells, (3) clefts within fibrous tissue without inflammation, and (4) phagocytized lipid contained within lipid-filled histiocytes (“foamy” macrophages).

Usually the eye can maintain cholesterol in aqueous solution, but that is impaired in an eye with synchysis scintillans, suggesting that the vitreous may act as a cholesterol sink in this condition because abnormally high levels of cholesterol ester are observed. ⁸ Cholesterol particles in the anterior chamber are rare, and it has been hypothesized that there are 2 processes that allow this to occur. The first involves intravitreal cholesterol particles directly entering the anterior chamber from the vitreous cavity via the pupillary space, whereas the second involves proteins and fats that are released from the posterior segment of the eye and enter the anterior chamber with the flow of intraocular fluid, with cholesterol particles forming in the anterior chamber. ⁹ The former process appears to be more consistent with this reported case because there were cholesterol clefts seen in the vitreous cavity. One way that cholesterol particles are considered to form is secondary to lysis of intraocular red blood cells, but in this case no red blood cells were seen on pathological examination. Alternatively, cholesterol-rich subretinal fluid without hemorrhaging can result in the formation of intraocular cholesterol particles, which migrate anteriorly. ^2,3,9

Conclusions

In conclusion, synchysis scintillans can manifest in the anterior chamber as crystals secondary to chronic retinal detachment even without aphakia or lens subluxation, and this case demonstrates a clinical pathological correlation that is representative of this rare condition.