What is your diagnosis?
BPEI Editors: D. Wilkin Parke III, MD, and Ryan F. Isom, MD
A 31-year-old Asian female was referred to the retina clinic complaining of decreased vision in the right eye. This decrease in vision had occurred insidiously over approximately 2 years. She complained of a noticeable central “grey spot” in the field of vision in the affected eye as well. There were no other associated ocular or systemic signs or symptoms. The patient’s medical history was unremarkable and she denied ocular trauma, systemic illness, or other medical issues. She was taking no medication and there was no family history of eye-related problems or vision loss.
Examination revealed a healthy-appearing 31-year-old female with a best corrected visual acuity of 20/70 in the affected eye and 20/20 in the left eye. The manifest refraction was –6.00 D sphere in the affected eye and –5.75 D sphere in the left eye. There were no adnexal abnormalities, and the pupils were equally round and without relative afferent pupillary defect. The patient’s eyes were without proptosis and were orthophoric in primary gaze with full ductions and versions. IOPs were 16 and 17 mm Hg in the right and left eyes, respectively, and confrontational visual fields were full to finger counting. The Amsler grid was within normal limits without metamorphopsia noted. Anterior segment exam showed normal eyelids and eyelashes, and the conjunctiva was white and quiet. The corneas were clear and the anterior chambers deep and quiet without cell or flare bilaterally. The iris and lenses were within normal limits bilaterally. Fundoscopic exam of the right eye (Figure 1) showed a yellowish lesion consistent with atrophy of the retinal pigment epithelium (RPE). The remaining macular and peripheral exam was unremarkable without hemorrhage or other retinal defects. The fundoscopic exam of the left eye (Figure 2) was unremarkable. The optic disc margins were sharp in both eyes and the cup-to-disc ratio was symmetrical. Fundus autofluorescence of the right eye (Figure 3) revealed hypoautofluorescence corresponding to the lesion previously noted in the center of the fundus of the right eye and highlighted the abnormality of the RPE. Fundus autofluorescence of the left eye (Figure 4) was unremarkable, showing that the RPE was intact. Macular optical coherence tomography (OCT) of the right eye (Figure 5) showed an exaggerated foveal indentation, a posterior bowing of the RPE with increased signal penetration through and into the excavated choroid. A magnified raster scan of the macula in the right eye (Figure 6) showed loss of the inner segment/outer segment (IS/OS) junction and further highlighted the disruption of the RPE. There also appears to be some thinning of the outer nuclear layer. The macular OCT of the left eye (Figure 7) shows a normal appearing retina and fovea with an intact RPE. There was a notable absence of foveal atrophy and RPE bowing in the left eye.
The differential diagnosis includes: early-onset macular degeneration, idiopathic central serous chorioretinopathy, myopic degeneration, posterior staphyloma, vitelliform dystrophy, solar retinopathy, and focal choroidal excavation.
Focal choroidal excavation (FCE) is a rare lesion in the macula first reported in 2006 by Dr. Jampol and colleagues. Since then, there have been fewer than 20 cases reported in the literature. It is seen on OCT as an excavation of the choroid in the fovea or perifoveal region that can have variable effect on visual acuity ranging from 20/20 to as poor as 20/100. It is usually unilateral but can be bilateral and there appears to be no racial or sex predilection.
Two types of FCE have been described: the conforming type and the nonconforming type. The conforming type is when the neurosensory retina is approximated to the retinal pigment epithelium, whereas the nonconforming type involves a space separating the neurosensory retina from the underlying, excavated RPE and choroid. There have not been reports of an associated RPE detachment with FCE. In the conforming type there has been described a thickening of the outer nuclear layer as compared with the areas of the retina not affected by the excavation. In our case the outer nuclear layer in the affected eye appeared to be thinned. Also, the conforming type has been described to have an intact IS/OS junction and our case demonstrates a disruption of this layer, likely explaining the decrease in visual acuity.
The etiology of these lesions is unclear but it has been proposed that this finding is a congenital lesion and that the conforming type precedes the nonconforming type. Many of the described patients have some degree of myopia, leading to the thought that these lesions possibly represent a microstaphyloma. Ultrasonography has been performed and generally demonstrates no evidence of staphyloma or underlying scleral ectasia. It has also been proposed that a localized choroiditis could lead to a collapse of the choroid and the resultant excavation. Choroidal bowing has been reported in association with other disease entities, including idiopathic central serous chorioretinopathy, polypoidal choroidal vasculopathy, and type 2 choroidal neovascularization.
Enhanced depth imaging (EDI) OCT permits superior visualization of the RPE and choroid. As with the introduction of other novel imaging modalities, we are sometimes presented with findings that extend beyond our current understanding of disease process. FCE may be such a finding. With such a limited amount of literature on the subject and an unknown natural history, observation with close monitoring of the patient’s symptoms is warranted. Our patient was educated about FCE and observed. This patient was counseled on the nature of her condition and will be monitored closely for anatomic or visual change in both eyes.
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