Progressive loss of vision caused by asymptomatic pituitary macroadenoma: role of OCT

INTRODUCTION: Most pituitary adenomas are clinically inactive. In patients with long-standing compression of the optic chiasm, ganglion cells may undergo axonal degeneration. Spectral domain optical coherence tomography (SD-OCT) is able to identify retinal nerve fiber layer (RNFL) and ganglion cell loss in the retina. We present a case in which SD-OCT was used to diagnose an asymptomatic pituitary macroadenoma. CLINICAL CASE: A 48-year-old female presented with progressive vision loss in both eyes. SD-OCT identified atrophy of the ganglion cell and nerve layers, with preservation of outer layers bilaterally. Magnetic resonance imaging of the brain showed a pituitary macroadenoma. The pathological diagnosis was nonfunctioning adenoma. DISCUSSION: As macroadenomas enlarge, they can induce uncrossed axon loss, resulting in nasal field defects and reduced visual acuity. In these cases, there is atrophy of the nasal and temporal portions of the optic disc, thus occupying a horizontal band across the disc. SD-OCT is able to identify RNFL loss in eyes with band atrophy of the optic nerve, which correlates with visual field defects found in perimetry. SD-OCT is a useful tool to assess the structural and functional damage of ganglion cells. In our case the SD-OCT demonstrated a symmetrical loss of the RNFL and the ganglion cell layer in both eyes, indicating important optic nerve damage.