First Author: S.Batta Arora INDIA
Co Author(s): G. Bhushan N. Goel A. Seth N. Saxena S. Thirumalai B. Ghosh 0 0 0 0 0 0 0 0 0
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To evaluate retinal nerve fibre layer (RNFL) thickness after brilliant blue (BB) assisted macular hole (MH) surgery and assess the usefulness of whole blood (WB) in the protection of RNFL.
Randomized controlled trial
Sixty eyes of 60 patients with stage 2-4 of idiopathic MH with a clear media and no history of glaucoma or any other disease that could affect RNFL measurements ( i.e. optic nerve atrophy ) were included. Patients were randomly divided equally in two groups. Group A patients underwent sequential intraoperative use of autologous heparinized WB followed by BB dye for staining internal limiting membrane (ILM) while patients in Group B were subjected to conventional BB staining of ILM. Clinical examination, fundus photographs and spectral domain optical coherence tomography (SD-OCT) was done preoperatively and postoperatively at 3 weeks, 6 weeks, 16 weeks and 6 months. Peripapillary RNFL thickness was evaluated at a calculated 3.45 mm diameter around the centre of the disc. Mean total, mean temporal and mean nasal RNFL thickness were assessed.
Mean total RNFL thickness in Group A was 105.73 ± 10.9 µ preoperatively and it decreased significantly at 6 weeks (p=0.001), 16 weeks (p<0.001) and 6 months (p<0.001). In Group B mean total RNFL thickness was 103.3±5.8µ preoperatively which significantly decreased at 6 weeks, 16 weeks and 6 months (p<0.001). Mean total RNFL thickness in Group B was significantly lower than Group A at 3 weeks, 6 weeks and 16 weeks (p=0.03). Mean temporal RNFL thickness in Group A decreased significantly at 6 weeks (p=0.007) and 16 weeks (p=0.008) from a preoperative value of 78.3±14.7µ. Mean temporal RNFL thickness in Group B was 75.2±7.8µ preoperatively and significant decrease was noted at all postoperative visits (p<0.001 at 3 weeks, 6 weeks, 16 weeks and 6 months). Difference between the two groups was significant 3 weeks onwards (p=0.004 at 3 weeks, 0.023 at 6 weeks, 0.033 at 16 weeks and <0.001at 6 months). Postoperative mean nasal RNFL thickness did not differ significantly from preoperative value in Group A or B. The difference between the two groups was also insignificant at all the visits.
BB assisted MH surgery results in loss of RNFL thickness which is more pronounced in the temporal quadrant. Because the ILM is thickest at the posterior pole of fundus, a high concentration of BB might remain within the ILM in the posterior pole except in the macular region where ILM was removed during surgery. The retained BB might be distributed over the inner retina and then transported towards the optic disc causing reduction of RNFL thickness. Since the dye is injected over the macular area during the surgery, its concentration is expected to be higher temporal to the disc which may explain loss of RNFL thickness temporally and not nasally. Though after injecting blood, redundant blood was removed using a flute needle, a thin layer of blood may have been left which acted as a barrier between ILM and dye and thus offered some protection to RNFL.