Correlation of pre-operative and post-operative retinal nerve fibre layer thickness with visual outcome following decompression of pituitary macroadenoma

Abstract

Objective

To (i) correlate preoperative retinal nerve fibre layer (RNFL) thickness with visual parameters in patients with pituitary macroadenomas. (ii) study the predictive role of preoperative RNFL in visual outcome following surgery for pituitary macroadenomas (iii) correlate change in postoperative RNFL thickness (RNFLT) with visual outcome.

Methods

Preoperative and post-operative RNFL thickness of thirty-three consecutive patients operated for pituitary macro adenoma between June 2022 and May 2023 were measured using Optical Coherence Tomography (OCT) and compared with standard visual examination findings and Magnetic Resonance Imaging (MRI) measurements.

Results

A total of 66 eyes of 33 patients who underwent surgical excision of pituitary macro adenoma between June 2022 and May 2023 were studied. The mean age in years of the study group was 44.36 ± 13.77 and both sexes were equally represented (Male: Female = 16:17). RNFL thinning predominantly involved the temporal (51.21+/-15.19 μm) followed by nasal quadrants (62.67+/- 17.03 μm) and correlated well with the visual field (VF) deficit (p <0.001). Patients with severe disc pallor had extremely thin RNFL (less than 67 +/- 8.68 μm). Patients with moderate to severe visual acuity (VA) deficits had significantly thinner RNFLs (65.08±7.09) compared to patients with normal to mild impairment in vision. (83.185±1.2) (p<0.05). RNFL values were significantly thinner for patients with Wilson Grade C, D and E tumours (66.13 ±12.19 μm) compared to those in Grade A and B (77.67±22.12 μm). The mean preop RNFL of patients who showed post-operative improvement in vision was 87.025± 15.02 μm, of patients in whom vision remained static was 74.58 ±18.31 μm. The mean VA (Decimal) increased from a minimum of 0.60 at the pre-operative timepoint to a maximum of 0.68 at the post-operative timepoint. (Wilcoxon Test: V = 42.5, p = <0.001). The mean RNFLT (µm) increased from 77.14 μm at the pre-operative timepoint to 83.77 μm at the post-operative timepoint. (Wilcoxon Test: V = 218.0, p = <0.001). The mean change of RNFL in patients in whom vision improved was 3.6 μm and the mean change of RNFL in patients in whom vision remained static was 9.51 μm. Absence of postoperative visual improvement was noted despite postoperative RNFL thickness improvement in eyes which showed significant preoperative thinning of the nasal (<65 μm) and temporal (<52μm) quadrants.

Conclusion

RNFL thinning corelates directly with visual acuity, visual field, and optic disc pallor. Patients with pituitary adenoma have preferential thinning of temporal and nasal quadrants. Visual outcome is better in patients with preserved RNFLT of values more than 82 +/- 5 μm. Reversal of RNFL thinning postoperatively need not necessarily correlate with visual improvement especially in patients who showed significant preoperative thinning of nasal and temporal quadrants.