Neuro-ophthalmological symptoms of compressive optic neuropathy depending on chiasmal position and pituitary adenoma extension

Objective: to analyze the characteristics of compressive optic neuropathy depending on the anatomical position of the optic chiasm. Materials and methods: The study was conducted at the A.P. Romodanov Institute of Neurosurgery of the National Academy of Medical Sciences of Ukraine between 2018 and 2024, within the Departments of Endonasal Skull Base Neurosurgery and Neuro-ophthalmology. We retrospectively analyzed data from a consecutive surgical series involving 212 patients (424 eyes) diagnosed with pituitary adenoma (PA) and compressive optic neuropathy manifested by decreased visual acuity and/or visual field defects. The cohort included 116 women (54.7%) and 96 men (45.3%) aged 18 to 76 years (mean age 52.3 ± 11.8 years). Based on the direction of PA growth and the anatomical position of the optic chiasm, patients were classified into three groups: Group I – anterior growth and/or posterior chiasmal position (34 patients, 16.1%; 68 eyes); Group II – suprasellar growth and/or central chiasmal position (147 patients, 69.3%; 294 eyes); Group III – posterior growth and/or anterior chiasmal position (31 patients, 14.6%; 62 eyes). Results: No statistically significant difference in mean age was observed among the groups (p > 0.05). The mean duration of visual impairment was (14.8 ± 3.9) months in Group I, (8.80 ± 0.95) months in Group II, and (9.1 ± 2.5) months in Group III (p > 0.05). Mean visual acuity was 0.60 ± 0.05, 0.60 ± 0.03, and 0.60 ± 0.04, respectively (p > 0.05). Mean cumulative loss of light sensitivity was (10.39 ± 0.80) dB, (11.2 ± 0.3) dB, and (10.25 ± 0.80) dB in Groups I, II, and III, respectively (p > 0.05). The mean tumor volume of PA was significantly larger in Groups I ((20.4 ± 6.7) cm³) and III ((24.9 ± 5.9) cm³) compared to Group II ((9.02 ± 0.59) cm³) (p < 0.05). Regarding visual field patterns: posterior chiasmal position was associated with superior temporal quadrantanopia (32.4%), central chiasmal position with temporal hemianopia and central scotoma (30.6%), anterior chiasmal position with homonymous hemianopia (35.5%). Conclusions. In patients with pituitary macroadenomas, visual disturbances may be delayed or absent when the chiasm is located in anterior or posterior positions. This is likely due to reduced compressive impact on the opto-chiasmal complex in these anatomical configurations.