GCLs

GCLs is an acronym used in neuroscience and vision science to denote ganglion cell layer(s) of the retina, though in some contexts it may refer to granule cell layers in other brain regions. In the retina, the ganglion cell layer is a thin layer located between the inner limiting membrane and the inner plexiform layer, and it contains the somata of retinal ganglion cells whose axons form the optic nerve.

Retinal ganglion cells relay visual information from photoreceptors through bipolar and amacrine cells to central targets in the brain. The GCL includes several ganglion cell types, such as midget and parasol cells, which contribute to different aspects of visual processing, including acuity and motion detection. The organization of the GCL, along with the adjacent nerve fiber layer, supports the transmission of signals generated by the retina to higher visual centers.

Clinically, thinning of the GCL is associated with optic neuropathies, most notably glaucoma, where loss of retinal ganglion cells leads to measurable thinning of the GCL and the retinal nerve fiber layer. Thickness measurements of the GCL are commonly obtained using optical coherence tomography (OCT) with automated segmentation to aid in diagnosis and monitoring of disease progression.

Imaging and assessment methods: OCT and other retinal imaging modalities enable quantification of GCL thickness, facilitating longitudinal monitoring and research into retinal structure–function relationships. In a broader context, GCLs can also refer to granule cell layers in various brain regions, such as the cerebellar granule cell layer, with the exact meaning dependent on anatomical context.