Bacillary Layer Detachment (BALAD) in Macular Choroidal Metastasis of a Low-grade Rectal Adenocarcinoma

Introduction

Choroidal metastases are the most common intraocular malignant tumors in adults [1]. Because of its large vascular network, the choroid is the most frequently involved ocular layer. The majority of patients with choroidal metastasis have been previously diagnosed with systemic cancer. In one-third of the patients, the choroidal metastasis is found before the primary tumor [1]. Breast (45%) and lung cancer (25%) are the most common primary neoplasms [1]. The gastrointestinal tract (4%), in particular, the rectum (< 0.5%), is an unusual site of origin [1], [2].

Management of choroidal metastases is an emergency and requires close multidisciplinary teamwork, often involving radiation therapy, to avoid blindness and neovascular glaucoma because of total retinal detachment secondary to rapidly growing tumors. Multimodal imaging in the ophthalmic workup of these patients is essential, and optical coherence tomography enhanced depth imaging (OCT-EDI) has become an important tool in ocular oncology, especially in macular tumors.

Bacillary layer detachment (BALAD) is a novel OCT terminology and is defined as a split at the level of the photoreceptor inner segment myoid, creating a distinct intraretinal cavity [3]. The photoreceptor inner segments are divided into two parts: the proximal myoid, near the external limiting membrane, and the distal ellipsoid zone (near the outer segment) [3]. The first OCT description of BALAD was made by Maruyama and Kishi [3] in a series of 21 patients with Vogt-Koyanagi-Harada (VKH) disease as “intraretinal fluid accumulation in the outer retina”. Rhamtohul et al. proposed a novel acronym “BALAD” (BAcillary LAyer Detachment) [3].

Publication History

Received: 26 September 2021

Accepted: 17 February 2022

Article published online:
26 April 2022

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