Chronological Analysis of Visual Field and Optic Nerve Thickness for the Early Diagnosis of Bilateral Chronic Open-Angle Glaucoma With a Masquerading Growing Pituitary Tumor.

This case illustrates that a pituitary tumor can be masked by coexisting glaucoma, and that early differential diagnosis using optical coherence tomography (OCT), Central 24-2 threshold visual field testing, and magnetic resonance imaging (MRI) to facilitate timely surgical intervention might avoid irreversible vision loss. A 73-year-old female was initially diagnosed with cataracts and glaucoma and monitored by retinal nerve fiber layer (RNFL) measurements using OCT, with readings of 97 μm in the right eye and 85 μm in the left eye in 2010. This case was followed continuously by the author for over 17 years. Although her intraocular pressure remained well controlled, her left eye RNFL progressively declined, dropping to 72 μm in 2022 and further to 62 μm in 2025. Visual field testing in 2016 revealed bitemporal defects, including a glaucomatous arcuate defect, which became increasingly pronounced by 2020 and, by 2025, demonstrated severe defects in the left eye, inconsistent with controlled glaucoma. MRI in 2025 confirmed a 2.2 cm adenoma compressing the optic chiasma with left optic nerve atrophy. In retrospect, review of the chart revealed early warning signs of a brain lesion, and the tumor was unfortunately identified only after significant vision loss had already occurred, underscoring that early diagnosis and timely surgery can prevent and sometimes reverse vision loss. Any atypical glaucoma presentation or inexplicable change in a patient with controlled glaucoma should therefore be carefully evaluated to exclude pituitary or other intracranial tumors, particularly through diligent visual field review and optic nerve examination. Glaucoma is fundamentally an optic nerve disease, and multidisciplinary cooperation is essential: neurologists managing pituitary tumor patients should refer them to ophthalmologists to rule out coexisting glaucoma, while ophthalmologists encountering unusual glaucoma cases should refer patients to primary care physicians or neurologists to exclude intracranial pathology. This report aims to remind clinicians of this rare but well-documented condition and highlight early diagnostic clues to prevent the pituitary tumor from being masked by a narrow specialty focus.