Background: The main mechanism of optic nerve damage in patients with pituitary adenoma (PA) is the pressure of optic chiasm. The retinal nerve fiber layer (RNFL), the ganglion cell layer (GCL)+, and GCL++ thickness measurement by optical coherence tomography (OCT), visual function evaluation, and magnetic resonance imaging (MRI) can be used to predict visual function recovery. In our study, we investigated the associations between visual acuity (VA), visual field (VF), RNFL, GCL changes, and the findings of MRI in patients with PA. Methods: This study was conducted in the Departments of Ophthalmology and Neurosurgery of the Lithuanian University of Health Sciences Hospital. A total of 25 patients diagnosed with PA were included in the study group, and 27 healthy subjects were included in the control group. The thickness of the RNFL and ganglion cell layer (GCL+, GCL++) and optic nerve disc diameter was analysed with OCT. Moreover, an MRI was performed for patients with PA. Results: The RNFL thickness around the optic disk measured preoperatively was reduced significantly in the temporal quadrant in PA patients compared with the control group (median (min; max); mean rank: 73.5 (52; 109); 58.39 vs. 69.5 (16; 168); 46.14; p = 0.038). We found that it was reduced significantly only in the inferior quadrant of the macro-PA group compared to the micro-PA group (median (min; max); mean rank: 99.5 (61; 115); 21.07 vs. 106.5 (90; 121); 32.15), p = 0.008, respectively). The RNFL thickness was reduced significantly only in the inferior quadrant of the non-active PA group compared to the active PA group (median (min; max); mean rank: 118.5 (49; 144); 17.42 vs. 130.5 (77; 156); 28.05), p = 0.028, respectively). RNFL thickness was reduced significantly only in the temporal quadrant in the PA with suprasellar extension group compared to the PA without suprasellar extension group (median (min; max); mean rank: 67.5 (16; 99); 21.66 vs. 72 (58; 168); 30.39), p = 0.036, respectively). Furthermore, GCL++ thickness was reduced significantly in total and in superior and inferior sectors of the PA with suprasellar extension group compared to the PA without suprasellar extension group (median (min; max); mean rank: 98.5 (57; 113); 21.8; 101 (61; 121); 21.48 and 102.5 (59; 116); 21.71 vs. 103.5 (95; 115); 30.2; 106.5 (90; 115); 30.61 and 104.5 (95; 113); 30.32), p = 0.043; p = 0.028 and p = 0.038, respectively). In the control group, significant positive correlations were found between optic disc area and the total RNFL thickness (r = 0.440, p < 0.001). In the PA group, significant correlations were observed between optic rim area and total RNFL thickness (r = 0.493, p < 0.001) and all quadrants, with the strongest in the nasal quadrant (r = 0.503, p < 0.001). A moderate to strong negative correlation was found between visual field (VF) defects and RNFL thickness, with the strongest correlation observed in the superior quadrant. Conclusions: OCT offers a detailed insight into the microscopic structural and functional changes throughout the entire visual pathway in patients with PA. Our findings demonstrate a significant negative correlation between RNFL thickness and visual field defects, highlighting the clinical relevance of OCT measurements in visual function assessment. Moreover, the results suggest that optic rim area may be a more reliable indicator of RNFL thickness variations than optic disc area in patients with PA.

Ryanodine receptor 2 (RyR2) has been increasingly recognized as an important regulator in cancer biology. Previous studies demonstrate that RyR2 expression is associated with patient survival, although its precise role in tumorigenesis remains unclear. Elevated RyR2 expression has been linked to poorer survival outcomes, while gene silencing or pharmacological inhibition (e.g., with S107) has been shown to reduce cancer cell metastasis in both in vitro and in vivo models. Cytokeratin 18 (CK18), a key epithelial marker, is associated with tumor differentiation, hormonal phenotype, and clinical behavior in pituitary neuroendocrine tumors (PitNETs), reflecting underlying cytoskeletal organization. Variations in CK18 expression have been linked to distinct adenoma subtypes and may provide insight into tumor aggressiveness. This exploratory study investigated associations between RyR2 expression, CK18 status, and conventional MRI findings of pituitary tumors. Quantitative T2-weighted signal intensity and radiomic features were not assessed. This exploratory observational study used prospective patient recruitment between January 2017 and January 2026, after ethics approval was obtained in December 2016. RyR2 expression in immunohistological samples was quantified using QuPath v0.6.0. CK18 immunostaining was performed with the Dako Omnis system according to the manufacturer’s protocols. Conventional MRI findings were available for 24 patients and were retrospectively reviewed. Statistical analysis was conducted using SPSS/W 31.0. No statistically significant associations were observed between RyR2 expression and sex, hormonal activity, tumor size, invasiveness, recurrence, or the evaluated conventional MRI findings (all p > 0.05). The only statistically significant finding was higher RyR2 expression in CK18-negative than in CK18-positive tumors (median (IQR): 2.49% (18.36%) vs. 0.06% (0.39%); p = 0.006; r = 0.47). Higher RyR2 expression was observed in CK18-negative tumors. Given the exploratory design and limited sample size, this association should be considered hypothesis-generating and requires validation in larger independent cohorts.