Case of the Month

Edited by Robert N. Johnson, MD
Type Case, Month

Presented by Malini Veerappan Pasricha, MD

A 51-year-old Hispanic female with long-standing severe vision loss of the right eye.

Figure 1: Wide-field color photo of the right eye. Note the subtotal retinal detachment with areas of subretinal fibrosis and large discrete retinal elevations.

Case History

She reported a steady decline in her vision over the last ten years. Due to financial and social constraints, she was unable to seek care. She denied any recent flashes, floaters, metamorphopsia, or headaches. Her past ocular history was significant for right-sided Bell’s Palsy, diagnosed and spontaneously improved in the 1980s. Her medical history was significant for hyperlipidemia and hypertension, controlled on oral therapy. She denied any history of malignancy or trauma. Family history was significant for hypertension and type 2 diabetes. Her social history was unremarkable. Review of systems was negative.

Her best corrected Snellen visual acuity measured light perception (LP) in the right eye (OD) and 20/20 in the left eye (OS). Her intraocular pressure was 18 mmHg in both eyes (OU). She had a right eye exotropia. The left eye exam and imaging were unremarkable. Anterior segment examination of the right eye was significant for 1+ posterior subcapsular cataract and pigmented cells in the anterior vitreous. The posterior examination of the right eye showed a subtotal retinal detachment with subretinal fibrosis extending from the optic nerve to the superior periphery. There were two large cystic lesions, one in the macula and another in the temporal periphery. The optic nerve appeared healthy (Figure 1). Though image signal was suboptimal, optical coherence tomography (OCT) of the macula demonstrated retinal detachment with severe atrophy of the retina (Figure 2).

Figure 2: OCT of the right eye. Poor signal quality due to the media. Retinal detachment is present with significant retinal atrophy noted.

What is Your Diagnosis?

Differential Diagnosis

Diagnosis and Patient Course

This patient has a chronic macula-off subtotal retinal detachment, with proliferative vitreoretinopathy (PVR). The cystic lesions in the macula and temporal periphery are most consistent with retinal macrocysts. After an extensive discussion about the guarded visual prognosis, the decision was made to proceed with surgery. The patient underwent a vitrectomy with subretinal membrane dissection, endolaser, and silicone oil tamponade. The surgery involved an inferior retinotomy and perflurocarbon liquid, as well as drainage of the large macular macrocyst. At post-op month one (POM1) visit, the visual acuity was CF with an attached retina. The retinal macrocysts were collapsed (Figure 3). OCT demonstrated significant post-operative macular edema, which was treated with topical steroids (Figure 4).

Figure 3:Wide-field photo of the right eye postoperatively. The retina is reattached and the retinal macrocysts are collapsed

Figure 4: OCT of the right eye. Significant CME is present.

Discussion

Retinal macrocysts are most commonly encountered with chronic retinal detachments (incidence of 3%),1 though they have also been reported in other retinal pathologies such as retinal dialysis, ocular cysticercosis, Coats disease, and metastatic choroidal tumors.1-7 A prior case report by Karimi et al describes subretinal macrocysts as an atypical presentation of ocular toxoplasmosis.8 In our patient, it is plausible that the chronic retinal detachment was secondary to a prior ocular toxoplasma infection. No active toxoplasma lesions were noted on exam, but she grew up in Mexico and the breaks noted during intraocular surgery were smaller and atrophic (as opposed to large horseshoe tears or retinal dialyses). As discussed in the aforementioned case report, large subretinal cysts, proliferative vitreoretinopathy, and exotropia could be consistent with a long standing rhegmatogenous retinal detachment secondary to necrotizing toxoplasma retinochoroiditis and self-sealing retinal breaks.8

Attempts have been made to classify retinal cysts. Size of the cyst, though somewhat arbitrary, is one such classification: small (1mm) to medium (2-10 disc diameters) to large (25% or greater of the fundus).2,9 Peripheral cystoid degeneration is a term used to describe numerous small cysts in the periphery. Typically, it starts at the ora serrata within the outer plexiform and inner nuclear layers, tends to occur bilaterally, and poses minimal increased risk for retinal detachment. Coalescence of these lesions can lead to retinoschisis.10 Medium size cysts, also known as retinal macrocysts, usually develop as a consequence of a chronic retinal detachment. They tend to be well-circumscribed and located at the equator.1-5 The cysts are not thought to be a consequence of inner or outer retinal holes, as in retinoschisis. Rather, the pathogenesis has been attributed to chronic subretinal fluid causing choroidal ischemia and subsequent photoreceptor atrophy, leading to degenerative cystic changes.4 Macrocysts may be intraretinal or subretinal, though they most commonly occur within the outer plexiform layer owing to its looser synaptic connections and watershed area of retinal circulation.1-5 Retinal macrocysts can also be hemorrhagic in nature, suggestive of a ruptured retinal vessel within the cyst. Careful diagnostic evaluation must be undertaken in these cases to differentiate from underlying malignant and vasoproliferative tumors.11

OCT and B-scan are helpful diagnostic tools. In a retinal macrocyst, B-scan would show a smooth, oval, anechoic image (hyperechoic if hemorrhagic) while A-mode echography would typically show a reflectivity spike higher than 98% indicating retinal origin.12 Most macrocysts do not require any specific treatment, and resolve spontaneously after surgical repair of the associated retinal detachment.1-5 Hemorrhagic retinal macrocysts may take longer to resolve.11 However, when the macrocyst is localized at or near a retinal break, it can prevent retinal reattachment and surgical drainage of the cyst may be necessary.1-5 Some surgeons may elect to excise the cyst and surrounding retina during vitrectomy, especially if this incorporates into a retinotomy.13 One report suggests that Nd:YAG laser can be used post-operatively to perforate a macrocyst that is otherwise hindering post operative retinal re-attachment, especially in cases of primary scleral buckle where intraoperative drainage may be more challenging.14

Take Home Points
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References
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