|Year : 2022 | Volume
| Issue : 2 | Page : 585-586
Bacillary layer detachment in carotid–cavernous fistula
Rashmi Pawar1, M Usha2, Pradeep Sagar1, HN Ravishankar1, Suchitra Biswal1
1 Department of Vitreo-Retina, Sankara Eye Hospital, Shimoga, Karnataka, India
2 Department of Oculoplasty, Sankara Eye Hospital, Shimoga, Karnataka, India
|Date of Submission||27-May-2021|
|Date of Acceptance||11-Sep-2021|
|Date of Web Publication||13-Apr-2022|
Sankara Eye Hospital, Harakere, Shimoga, - 577 202, Karnataka
Source of Support: None, Conflict of Interest: None
Keywords: Bacillary layer detachment, carotid–cavernous fistula, optical coherence tomography
|How to cite this article:|
Pawar R, Usha M, Sagar P, Ravishankar H N, Biswal S. Bacillary layer detachment in carotid–cavernous fistula. Indian J Ophthalmol Case Rep 2022;2:585-6
|How to cite this URL:|
Pawar R, Usha M, Sagar P, Ravishankar H N, Biswal S. Bacillary layer detachment in carotid–cavernous fistula. Indian J Ophthalmol Case Rep [serial online] 2022 [cited 2022 May 24];2:585-6. Available from: https://www.ijoreports.in/text.asp?2022/2/2/585/342884
A 33-year-old gentleman presented with diminution of vision, swelling, and inability to close the left eye since 1 week following head injury. Best-corrected visual acuity (BCVA) in the right eye was 20/20, and the left eye was counting finger at 2 m. Left eye examination revealed frozen globe, lagophthalmos, proptosis, inferior conjunctival grade 3 chemosis with prolapse, dilated episcleral vessels, and dilated pupil reacting sluggishly to light [Figure 1]a. Fundus examination showed dilated, tortuous veins, retinal hemorrhages, and pockets of fluid resembling neurosensory detachment [Figure 1]b. But optical coherence tomography (OCT) showed hyporeflective space in the outer retina above the ellipsoid zone suggestive of bacillary layer detachment (BLD) [Figure 1]d. Subfoveal choroidal thickness (SFCT) was 363 microns. Computed tomography angiogram showed enlarged left cavernous sinus with lateral convex bulge and dilatation of left superior ophthalmic vein and its tributaries suggesting left-sided carotid–cavernous fistula (CCF) likely involving the cavernous segment of the left internal carotid artery. So a diagnosis of venous stasis chorioretinopathy secondary to CCF was considered. The patient underwent endovascular embolization of CCF. At 4 months follow-up, BCVA in the left eye was 20/40. Fundus examination showed sheathing of vessels along the superotemporal and inferotemporal arcade, dot and blot hemorrhages, and hard exudates [Figure 1]c. OCT showed normal foveal contour, resolution of BLD, patchy loss of ellipsoid zone [Figure 1]e, and reduction in SFCT to 167 microns.
|Figure 1: (a) Clinical photograph of the left eye at presentation showing proptosis, inferior conjunctival chemosis with prolapse, dilated episcleral vessels, and dilated pupil. (b) Color fundus image at the time of presentation showing blurred disc margins, dilated and tortuous veins, and pocket of fluid in the center of macula. (c) Color fundus image after treatment showing pale disc, sheathing of blood vessels, dot blot hemorrhages, and hard exudates. (d) Optical coherence tomography image at presentation showing a large hypo reflective space in the outer retina above the ellipsoid zone suggestive of bacillary layer detachment. The continuity of the ellipsoid zone along the outer wall of hyporeflective space is indicated by the yellow arrowhead. Choroidal thickening is seen (dotted line). (e) Optical coherence tomography image showing normal foveal contour, resolution of bacillary layer detachment, and patchy ellipsoid zone loss. Reduction in choroidal thickness is seen (dotted line)|
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| Discussion|| |
BLD is a recently described term in which fluid accumulation leads to splitting of outer layers of the retina. It is postulated that the fluid may accumulate in the myoid zone or between the outer and inner segments of photoreceptors or between ellipsoid and myoid zone or within the ellipsoid zone. It is described in Vogt Koyanagi Harada disease, tubercular choroidal granuloma, ocular toxoplasmosis, acute posterior multifocal placoid pigment epitheliopathy, posterior scleritis with antiphospholipid antibody syndrome, choroidal metastases from breast and lung tumor, Dabrafenib and Trametinib retinal toxicity., In this case, BLD was seen secondary to traumatic CCF, which resolved completely after endovascular embolization. To the best of our knowledge, BLD is not reported in CCF. In CCF, the venous drainage from the retina and choroid is impeded due to raised venous pressure in the cavernous sinus. The resultant venous stasis and higher hydrostatic pressure in choroidal vessels may force the fluid into the subretinal space and outer retina. The choroidal thickening at presentation would be due to venous stasis in choroid. But the mechanisms involved in fluid accumulation in outer retina rather than subretinal space is not known. Normal venous pressure within the cavernous sinus following embolization facilitates venous drainage from the choroid and retina, which could explain the resolution of BLD. The reduction of choroidal thickness following embolization supports this hypothesis. Being a new entity with a lack of histological correlation, BLD is less understood. The exact location of fluid accumulation is not known. In the initial description, Mehta et al. hypothesized that photoreceptors have an inherent weakness at the level of the myoid, and the inner segment can detach from the nucleus. Bacillary layer (photoreceptor inner and outer segment) detachment is known to be a histological artifact and would support the above hypothesis. But this hypothesis would not explain the rapid resolution of BLD and rapid restoration of good vision. Further studies evaluating the changes in BLD at short intervals and histological correlation would be required to understand this entity.
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.
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