to demonstrate the usefulness of enhanced depth imaging optical coherence tomography ( edi - oct ) in investigating choroidal lesions inaccessible to ultrasound sonography .
in a 60-year - old woman with an asymptomatic choroidal nevus , normal oct was used to observe the macula and edi - oct to image the choroidal nevus that was inaccessible to ultrasound .
the exact location of the lesion in the choroid and the dimensions of the nevus were measured .
the lesion was located in the superior macula , and the nevus was homogeneous in its reflectivity .
we observed a thickened choroid delineated by the shadow cone behind it , measuring 1,376  325 m in the larger vertical cut and 1,220  325 m in the larger horizontal cut in an image with a 1:1 pixel mapping and automatic zoom .
edi - oct appears to be an excellent technique for measuring choroidal nevi and all choroidal lesions accessible to oct imaging by depicting their exact location in the choroid , their dimensions , and their demarcation from the surrounding healthy tissue , thus allowing for a more efficient and accurate follow - up .
choroidal nevus is the most common tumor of the ocular fundus , present in 7% of the white population [ 1 , 2 ] . despite its benign nature
, it presents a risk of visual loss and visual field loss , and can rarely transform into malignant melanoma .
optical coherence tomography ( oct ) and ultrasonography have been used for imaging choroidal nevi . recently
, enhanced depth imaging oct ( edi - oct ) has been used in order to measure choroidal thickness in normal and pathologic eyes [ 3 , 4 ] . here
, we report a case of a flat choroidal nevus inaccessible to ultrasound sonography that was evaluated by edi - oct .
a 60-year - old woman was referred to our department with an asymptomatic choroidal nevus in her left eye . her best - corrected visual acuity was 20/20 in both eyes . slit lamp and fundus examinations of the right eye were normal . in the left eye , the anterior segment was normal ; however , on fundoscopy a choroidal nevus located in the superior macula was observed ( fig .
spectral - domain ( sd ) oct ( heidelberg engineering , heidelberg , germany ) revealed normal foveal thickness ( fig .
2 ) . the flat nevus was inaccessible to ultrasound sonography , and edi - oct was used to image its posterior surface ( fig .
edi - oct is a new technique that consists of positioning a heidelberg sd - oct close enough to the eye in order to obtain an inverted image , averaged for 100 scans .
the advantage of this technique is that the sensitivity of the imaging in deeper tissue layers is increased , and thus the obtained measurements are more accurate .
we employed this technique to image the location of the nevus in the choroid and obtain its dimensions as a reference measure for the follow - up examination ( fig .
3 ) . heidelberg sd - oct provides an exact correlation between the oct image and the infrared photograph . as infrared light
is absorbed by melanin , the nevus appears brighter . in the edi - oct image
, the lesion appears homogeneous and hyperreflective at the level of the large choroidal vessels , masking the underlying choroidal vasculature .
the choroidal thickness at the level of the nevus appears greater than the neighbor choroid ( fig .
the diameter of the nevus was calculated based on the presence of a shadow cone created by the lesion 's lateral borders .
the choroidal thickness was measured based on the hyperreflectivity between the bruch 's membrane and the beginning of the shadow cone ( fig .
the choroid measured 1,220  325 m in the larger horizontal cut and 1,376  325 m in the larger vertical cut in an image with a 1:1 pixel mapping and automatic zoom ( fig .
edi - oct appears to be an excellent technique for evaluating flat choroidal nevi that are inaccessible to ultrasound sonography and accessible to oct imaging , displaying simultaneously the lesion and the retinal changes .
it is a reproducible examination that allows depiction of the exact location of the nevi in the choroid , their dimensions and their demarcation from the surrounding healthy tissue . to date , the software available for sd - oct does not allow for objective measures .
the subjective measures obtained are useful upon comparison with the follow - up images . in order to limit the possibility of bias
, these follow - up images must be obtained and compared with the same sd - oct machine .
we believe that this technique is clinically useful and , together with color fundus photography , can provide a more efficient and accurate follow - up of choroidal nevi .
 purposeto demonstrate the usefulness of enhanced depth imaging optical coherence tomography ( edi - oct ) in investigating choroidal lesions inaccessible to ultrasound sonography.methodsin a 60-year - old woman with an asymptomatic choroidal nevus , normal oct was used to observe the macula and edi - oct to image the choroidal nevus that was inaccessible to ultrasound . 
 the exact location of the lesion in the choroid and the dimensions of the nevus were measured.resultsthe lesion was located in the superior macula , and the nevus was homogeneous in its reflectivity . 
 we observed a thickened choroid delineated by the shadow cone behind it , measuring 1,376  325 m in the larger vertical cut and 1,220  325 m in the larger horizontal cut in an image with a 1:1 pixel mapping and automatic zoom . 
 the macular profile and thickness were both normal.conclusionsedi-oct appears to be an excellent technique for measuring choroidal nevi and all choroidal lesions accessible to oct imaging by depicting their exact location in the choroid , their dimensions , and their demarcation from the surrounding healthy tissue , thus allowing for a more efficient and accurate follow - up . 
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