Best vitelliform macular dystrophy (VMD) is an infrequently occuring dystrophy caused by autosomal dominantly inherited mutations in the BEST1 gene.1–3
The recent introduction of spectral-domain optical coherence tomography (SD-OCT) has refined the clinical characterization of VMD, with visualization of the subretinal lipofuscin accumulation, fibrotic nodules under the retinal pigment epithelium (RPE), and disruption and atrophy of the outer retina and the RPE.4,5
Choroidal excavation was first described in 2006 to report an unusual macular finding characterized by macular choroidal excavation detected on OCT scan without evidence of a posterior staphyloma or scleral ectasia.6 More recently, this new entity, defined as focal choroidal excavation (FCE), has been characterized on SD-OCT and identified in patients with variable degrees of macular RPE changes, even in the absence of any visual complaint.7–9
We describe a case of VMD characterized by bilateral FCE on SD-OCT.
A 50-year-old man was referred for reduced visual acuity and metamorphopsia in both eyes. After written informed consent was obtained, the patient underwent a complete ophthalmological examination, including best corrected visual acuity (BCVA), tonometry, fundus biomicroscopy, color photography, fundus autofluorescence, and SD-OCT (Spectralis HRA-OCT; Heidelberg Engineering, Heidelberg, Germany). All procedures adhered to the tenets of the Declaration of Helsinki. Fluorescein angiography was not performed due to severe allergic complications.
BCVA was 20/80 and 20/100 in the right and left eyes, respectively. Intraocular pressure was normal, and anterior segment examination was unremarkable. Dilated fundus examination revealed the presence of bilateral VMD with accumulation of yellowish material and atrophic changes. Short-wavelength fundus autofluorescence revealed bilateral central hypofluorescence corresponding to the biomicroscopically detectable atrophic changes, surrounded by granular hyperfluorescence related to residual vitelliform material (Figures 1A and 1D). Near-infrared fundus autofluorescence revealed the absence of the typical central hyperautofluorescence with an external ring of faint hyperautofluorescence (Figures 1B and 1E).
Short-wavelength (A, D) and near-infrared fundus autofluorescence (B, E) of the right and left eyes, showing bilateral vitelliform macular dystrophy with accumulation of yellowish material and atrophic changes. SD-OCT (C, F) showing focal choroidal excavation in both eyes that corresponded to the center of the macular atrophy.
SD-OCT showed a hyporeflective area, more visible in the right eye, mimicking the presence of subretinal fluid, along with some hyperreflective vitelliform material. FCE could be identified in both eyes and corresponded to the center of the macular atrophy. The FCE was characterized by a wide disorganization of the retinal layers and disruption of the photoreceptors lines (Figures 1C and 1F). The external limiting membrane and the inner segment–outer segment (IS-OS) junction were interrupted, whereas the RPE was irregular and not clearly visible at the site of the excavation. Interestingly, a small intraretinal cyst was visible in the left eye (Figure 2A–B).
Electrooculogram was extinct, and genetic analyses confirmed the involvement of the BEST1 gene, c.73C>T (p.Arg25Trp).
Evaluation of the patient’s entire family revealed that a brother and two nephews were also affected by VMD.
Since the first description of choroidal excavation,6 new insights have been provided, especially with the advent of SD-OCT. Three cases of unilateral choroidal excavation on SD-OCT and metamorphopsia, even in the presence of a normal foveal contour in the inner retinal surface, have been described.7 In particular, the foveal excavation was situated under well-conserved integrity of the external limiting membrane (ELM) and IS-OS junction in two cases, while a disruption of the IS-OS junction was noted in the third subject. In two cases, the extent of choroidal excavation included the outer retina up to the ELM, whereas in the third eye only the RPE was involved.
Another retrospective case series analyzed 13 eyes with single or multiple FCE.8 Almost half of the patients reported metamorphopsia or blurred vision. Two of the affected patients presented with small acquired vitelliform lesions, and another two subjects presented with pigmentary changes and RPE atrophy corresponding to FCE. In all cases, the RPE followed the contour of the excavation. Conforming FCE was defined by the absence of any separation between the RPE and photoreceptor layer. In nonconforming FCE, a detachment between the RPE and photoreceptor layer was noted. Integrity of the IS-OS junction was associated with conforming FCE, whereas alterations or complete absence of the IS-OS interface (with a preserved ELM) were considered typical of nonconforming FCE.
More recently, 21 eyes of 17 patients with FCE were retrospectively evaluated over a mean follow-up of 37 months.9 Two subjects presented with similar vitelliform lesions at the posterior pole, whereas almost 24% of the patients noted bilateral involvement. In addition, the study showed that the choroid was thinner at the site of the excavation. In this longer follow-up, relatively stable findings have been reported.
To our knowledge, this is the first report of bilateral FCE in association with VMD. According to the SD-OCT features, characterized by interruption of the IS-OS junction and the presence of subretinal hyporeflective space, this case could be defined as nonconforming FCE.
Previous case series identified FCE in eyes presenting with RPE changes but no distinct clinical entity. The present case report indicates that choroidal excavation may be associated with specific macular disorders, and particularly with late-stage VMD, which is characterized by extensive RPE atrophy and outer retina changes.
Future investigations are warranted to ascertain the involvement of other macular dystrophies characterized by atrophic evolution and the impact of choroidal excavation on the clinical course.
- Boon CJ, Theelen T, Hoefsloot EH, et al. Clinical and molecular genetic analysis of Best vitelliform macular dystrophy. Retina. 2009;29(6):835–847. doi:10.1097/IAE.0b013e31819d4fda [CrossRef]
- Mohler CW, Fine SL. Long-term evaluation of patients with Best’s vitelliform dystrophy. Ophthalmology. 1981;88(7):688–692. doi:10.1016/S0161-6420(81)34965-3 [CrossRef]
- Deutman AF. Electro-oculography in families with vitelliform dystrophy of the fovea. Detection of the carrier state. Arch Ophthalmol. 1969;81(3):305–316. doi:10.1001/archopht.1969.00990010307001 [CrossRef]
- Schatz P, Bitner H, Sander B, et al. Evaluation of macular structure and function by OCT and electrophysiology in patients with vitelliform macular dystrophy due to mutations in BEST 1. Invest Ophthalmol Vis Sci. 2010;51(9):4754–4765. doi:10.1167/iovs.10-5152 [CrossRef]
- Kay CN, Abramoff MD, Mullins RF, et al. Three-dimensional distribution of the vitelliform lesion, photoreceptors, and retinal pigment epithelium in the macula of patients with best vitelliform macular dystrophy. Arch Ophthalmol. 2012;130(3):357–364. doi:10.1001/archophthalmol.2011.363 [CrossRef]
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- Wakabayashi Y, Nishimura A, Higashide T, Ijiri S, Sugiyama K. Unilateral choroidal excavation in the macula detected by spectral- domain optical coherence tomography. Acta Ophthalmol. 2010;88(3): e87–e91. doi:10.1111/j.1755-3768.2010.01895.x [CrossRef]
- Margolis R, Mukkamala SK, Jampol LM, et al. The expanded spectrum of focal choroidal excavation. Arch Ophthalmol. 2011;129:1320Y5. doi:10.1001/archophthalmol.2011.148 [CrossRef]
- Obata R, Takahashi H, Ueta T, Yuda K, Kure K, Yanagi Y. Tomographic and angiographic characteristics of eyes with macular choroidal excavation. Retina. 2013;33:1201–1210. doi:10.1097/IAE.0b013e31827b6452 [CrossRef]
Short-wavelength fundus autofluorescence (A) and SD-OCT scan (B) of the left eye revealing the presence of a small intraretinal cyst located into the center of the macular atrophy.