Multimodal imaging in a patient of Kranenburg syndrome

A 15-year-old girl presented with sudden onset painless diminution of vision in her left eye for past 2 months. Best-corrected visual acuity (BCVA) was 20/20 and counting finger at 1 metre in her right and left eye respectively. Dilated fundus examination and fundus imaging (Topcon TRC50IX fundus camera and Optos T × 200, Optos PLC, Dunfermline, Scotland, UK)) of left eye revealed an oval, greyish-yellow crater-like depression of size 1/10^th the disc diameter at the temporal aspect of optic disc suggestive of an optic disc pit (ODP) associated with serous macular detachment [Fig. 1]. Swept-source optical coherence tomography (SSOCT-Triton-Topcon, Tokyo, and Japan) of the macula revealed retinoschisis involving multiple layers and neurosensory detachment in the left eye extending up to temporal margin of the disc. [Fig. 2a and b]. Multicolor imaging (Spectralis-spectral domain optical coherence tomography system, Heidelberg Engineering, Heidelberg, Germany) clearly highlighted the areas of retinoschisis, neurosensory detachment and optic disc pit [Fig. 3]. Fundus autofluorescence (FAF-Spectralis, Heidelberg Engineering, Heidelberg, Germany) of macula of left eye showed central hypo and surrounding hyper autofluorescence [Fig. 4].

Figure 1.

Color fundus photograph of left eye depicting optic disc pit and associated serous retinal detachment

Figure 2.

SSOCT image of the left eye showing (a) retinoschisis between outer plexiform and nuclear layer (yellow star), outer layers in nasal retina with associated neurosensory detachment (yellow arrow) at macula; (b) retinoschisis between outer nuclear and plexiform layer (red star) which is not reaching up to optic nerve head with accompanying internal limiting membrane detachment extending up to disc (red arrow)

Figure 3.

Multicolor image of the left eye showed a greenish-grey hue at the macula due to elevation of the retinal contour secondary to retinal thickening with pinkish colour at the centre of the due to cystic schisis changes. A well-demarcated area in the temporal aspect of the optic nerve appeared darker than rest of the neurosensory rim corresponding with the optic disc pit. The outer brightest ring represents associated internal limiting membrane detachment

Figure 4.

Fundus autofluorescence image of left eye showing hypo autofluorescence at the centre suggestive of large schisis cavities. A band of hyperautofluorescence extending from disc to fovea noted, and probably representing flat retina

Discussion

Kranenburg syndrome is a rare congenital anomaly characterized by the presence of ODP with serous retinal detachment.[1] Serous retinal detachment is seen in around in 25-75% cases of ODP,[2] which if left untreated carries a poor prognosis. Therefore, early diagnosis with timely management becomes imperative. Large serous retinal detachment whimsically obfuscates the observation of ODP by closely abutting it in routine +90D slit lamp bio microscopy. Comprehensive retinal examination with multimodal imaging techniques can help to arrive at a diagnosis in such cases. In this case although ODP was visible clinically, much darker zone of optic disc rim in multicolor images[3] and presence of retinoschisis with neurosensory detachment on SSOCT confirmed the diagnosis of Kranenburg syndrome and helped us plan our management. FAF[4] also gives treasured information for appraisal of the Retinal Pigment Epithelium (RPE) photoreceptor complex and the metabolic condition of RPE in maculopathy associated with ODPs.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.