Jyoti Shetty,Sabita Paul, Sheetal Ballal, Fauqia
BACKGROUND
Pituitary adenoma is a benign and most common tumour of the pituitary gland. It is also the most common parachiasmal tumour and accounts for approximately 10-15% of primary intracranial neoplasms. It has an annual incidence rate of 0.8–8 per 1,00,000 population. Pituitary adenomas are classified as functional and non-functional based on their hormonal activity. Functional adenomas are usually detected earlier due to clinical manifestations produced by excess of hormones. The aim of the study is to analyse visual acuity, visual fields, RNFL thickness and GCIPL thickness on optical coherence tomography (OCT) and to find a correlation between these parameters and tumour volume in patients diagnosed with pituitary adenoma.
MATERIALS AND METHODS
48 patients diagnosed with pituitary adenoma confirmed by MRI scan underwent complete ophthalmic evaluation (visual acuity, slit-lamp examination, fundus evaluation), perimetry using 30-2 SITA FAST strategy, (Humphrey Field Analyzer; Carl-Zeiss Meditec, Dublin, CA), and OCT of disc (for retinal nerve fibre layer- RNFL thickness) and macula (for ganglion cell-inner plexiform layer (GCIPL) thickness) using Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, CA) at Bangalore West Lions Super Speciality Eye Hospital, between June 2014 to June 2016. Various parameters like Mean Deviation (MD), Pattern Standard Deviation (PSD) and RNFL and GCIPL thickness on OCT were analysed and correlated with each other.
RESULTS
Mean tumour volume in patients was 12.26 ± 15.8 cm3 . Most of the patients had visual acuity 6/18 or better. Bitemporal hemianopia was seen in only 5 (12.2%) patients. Superotemporal quadrantanopia, arcuate defects, tubular fields and homonymous hemianopia were the other field defects seen. Total and pattern deviation plot of visual fields correlated well with tumour volume and visual acuity. On visual field analysis, the MD (-8.18 ± 8.65 dB) was depressed compared to the control group (-2.0 ± 1.8 dB), and PSD value (5.76 ± 4.8 dB) was higher than controls (1.9 ± 1.0 dB). However, MD and PSD did not correlate well with tumour volumes. Mean RNFL thickness (85.9 ± 14.5 µm) and mean GCIPL thickness (71.6 ± 17.2 µm), values revealed global thinning in patients when compared with RNFL thickness (92.4 ±7.6 µm) and GCIPL thickness (80.4 ± 4.0 µm) in controls. MD and PSD correlated well with all sectors of RNFL and GCIPL (p value <0.01).
CONCLUSION
PSD and GCIPL were concluded to be valuable tools in prognosis of the disease. Our study reinforces the effectiveness of investigations like standard automated perimetry and OCT in prognosticating the neurological disorder like pituitary adenoma and to understand the structural and functional relationship of the disease process. Our study recommends the use of GCIPL thickness evaluation by OCT for patients with unreliable fields or fields not corresponding to the disease progress.
