Influence Of Pupil Dilation On Retinal Nerve Fibre Layer, Optic Nerve Head And Ganglionar Cell Complex Measurements With Spectral-Domain Optical Coherence Tomoghaphy (Rtvue-100)

Abstract

Purpose: : To evaluate the influence of pupil dilation on Retinal Nerve Fibre Layer (RNFL), Optic Nerve Head (ONH) and on Ganglionar Cell Complex (GCC) measurements with RTVue-100

Methods: : Patients with glaucoma were included in the study procedures and imaged with RTVue-100 OCT (Optovue Inc., Fremont, California, USA). All patients underwent a complete ophthalmological examination and automated perimetry (24-2 SITA standard on Humphrey Visual Field Analyzer; Carl Zeiss Meditec Inc., Dublin, CA, USA). Moreover all subjects underwent RNFL 3.45, ONH and GCC assessment with the RTVue-100 before and 30 minute after pupil dilation with one drop of tropicamide 1%.Continous data were expressed by mean and standard deviation (SD) of the values. Paired t-test pair test was used to evaluate differences between measurements and p-values lower than 0.05 were considered statistically significant

Results: : Forty-seven glaucoma patients were included in the study procedures. Mean age was 52.00±13.67 years; Mean deviation was -4.15±6.44 dB and sferical equivalent was 1.76±3.72 diopters. There was no statistically significant difference in signal strength index (SSI) in all scan protocol that we tested. RNFL 3.45 SSI was 58.08±10.25 before and 57.41±9.71 after pupil dilatation; (p=0.31). ONH SSI was 52.26±8.46 before and 50.29±8.47 after pupil dilatation; (p=0.06). GCC-SSI was 60.16±8.86 before and 59.45±9.90 after pupil dilatation. RNFL overall thickness measured by RNFL 3.45 scan were 89.59±14.85 µm before and 89.10 ±15.53 µm after pupil dilatation (p=0.23). There were no sectorial statistical significant differences before and after dilatation in RNFL 3.45 scan protocol. Disc area was1.80 ± 0.45 mm²before and 1.75 ± 0.52 mm² after pupil dilatation (p=0.15).Cup area was 2.29 ±12.84 mm² before and 2.69±7.80 mm² after pupil dilatation (p= 0.45). Rim area was 0.75± 0.41mm² before and 0.70±0.40mm² after pupil dilatation (p=0.11). GCC average thickness was 87.73±13.22 µm before and 87.97±12.62 µm after pupil dilatation (p=0.56).There were no statistical significant differences before and after dilatation in the other parameters in ONH or in GCC scan protocol.

Conclusions: : In conclusion the results show that RTVue SD-OCT signal strength is not affected by pupil dilatation and that measurements of RNFL, ONH and GCC parameters performed before and after pupil dilatation are equivalent.

Keywords: optic nerve • ganglion cells • imaging/image analysis: clinical