An Analysis of Retinal Nerve Fiber Layer Thickness before and after Pituitary Adenoma Surgery and its Correlation with Visual Acuity.

INTRODUCTION: Pituitary adenomas comprise approximately 10% of all intracranial tumors. Initially, subtle changes occur in the field of vision, which are difficult to assess clinically. It has been seen that following surgery of pituitary macroadenoma, total recovery of normal vision occurs in 35% of the patients, improvement of vision occurs in 60%, and in the rest there is no change in vision. Retinal nerve fiber layer thickness (RNFLT) undergoes retrograde degeneration following compression of optic apparatus by pituitary tumor. We planned a study to evaluate RNFLT before and after pituitary adenoma surgery and its correlation with visual acuity. MATERIAL AND METHODS: Twenty patients (40 eyes) with diagnosed pituitary adenoma were included in the study. Preoperative visual acuity, fundus and RNFL thickness were calculated using spectral-domain OCT Optovue, Heidelberg Engineering, Heidelberg, Germany (RT 100 version 5.1), and postoperative measurement was done after 1 and 3 months. Four-quadrant mean of RNFLT was calculated. Results were tabulated and analyzed. STATISTICAL ANALYSIS: Results of the study were analyzed using IBM SPSS Statistics version 19.0. RESULTS: There was no significant change in RNFLT after pituitary adenoma surgery, and it was found that patients with RNFLT within normal range preoperatively showed improvement in visual acuity after pituitary surgery. On the other hand, patients who had thinned-out RNFLT preoperatively showed no improvement in visual acuity. It was also found that once optic disc pallor sets due to chronic compression, then chances of its reversion to normal depend on its grading: only mild pallor disc has some chance to revert to normal, whereas moderate and severe pallor do not revert to normal. CONCLUSION: RNFLT and optic disc can be used as prognostic factors for evaluation of visual outcome in pituitary adenoma surgery.

Evaluation of pattern ERG as a visual prognosticator in chiasmatic tumours.

BACKGROUND: Tumours compressing the optic pathway may lead to irreversible loss of vision that can be detected by pattern electroretinogram owing to its relation to ganglion cell function. This study aims to assess whether pattern electroretinogram is a useful tool to predict visual outcome following decompressive surgery for sellar and parasellar tumours. DESIGN: Prospective, non-randomized study. PARTICIPANTS: Forty eyes of 20 patients with radiologically confirmed tumours in and around the sellar region. METHODS: Patients were followed for 6 weeks following surgical intervention (transphenoidal or transfrontal approach). MAIN OUTCOME MEASURES: Best-corrected visual acuity, visual fields (Humphrey 30-2 standard automated perimetry) and pattern electroretinogram. The ratio N95/P50 (N2/P1) was calculated for each recording. RESULTS: There was improvement in visual fields in 35.4% eyes with normal n2/p1 ratio (>1.1) as compared to 22.2% with abnormal ratio. Also, 9.6% eyes with normal ratio and 11.1% with an abnormal ratio deteriorated postoperatively. No association was found between pattern electroretinogram and visual fields preoperatively and postoperatively (P = 0.093). CONCLUSIONS: Pattern electroretinogram may not be a useful prognostic indicator in the preoperative assessment of tumours causing chiasmal compression. An abnormal N2/P1 ratio is not necessarily associated with lesser or no clinical improvement following surgery as compared to an eye with a normal pattern electroretinogram.