In Vivo Retinal Nerve Fiber Layer Thickness Measured by Optical Coherence Tomography Predicts Visual Recovery after Surgery for Parachiasmal Tumors
Helen V. Danesh-Meyer 1*,
Taras L Papchenko 2,
Peter J Savino 3,
Andrew Law 4,
James Evans 5,
and
Greg D Gamble 6
1 Department of Ophthalmology, University of Auckland, Private Bag 92019, Auckland, 1020, New Zealand
2 Department of Ophthalmology, University of Auckland, Auckland, New Zealand
3 Neuro-ophthalmology, Wills Eye Institute, Philadelphia, Pennsylvania, United States
4 Neuro-surgery, University of Auckland, Auckland, New Zealand
5 Neuro-surgery, Thomas Jefferson Medical School, Philadelphia, Pennsylvania, United States
6 Medicine, University of Auckland, Auckland, New Zealand
* To whom correspondence should be addressed. E-mail: h.daneshmeyer{at}auckland.ac.nz.
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Abstract |
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Objective: Restoration of visual function following neurosurgery for parachiasmal tumors is variable and unpredictable. We tested whether in vivo retinal nerve fiber layer(RNFL) thickness measurements predict the visual recovery of such patients.
Methods: Forty-one patients undergoing surgical resection of parachiasmal lesions were prospectively assessed pre-operatively with neuro-ophthalmic examination, standard automated visual field (VF) testing, and optical coherence tomography(OCT) measurements of RNFL thickness whichthickness that was the pre-specified marker for axonal loss. Tests were repeated within six weeks following surgery.
Results: Thinner pre-operative RNFL thickness was associated with worse visual acuity (VA) and VF mean deviation (MD). Patients with normal pre-operative RNFL had significant improvement in VA post-operatively from a mean of 20/40 to 20/25 (p= 0.028), while patients with thin RNFL did not improve (20/80 to 20/60, p=0.177). Eyes with normal RNFL showed improvement in MD (-7.0dB pre-operatively, -3.5dB post-operatively, p=0.0007) unlike eyes with thin RNFL whichRNFL, which had no significant improvement after surgery (-15.3 dB pre-operatively, -13.3 dB post-operatively, p=0.191). RNFL thickness increased by 1% after surgery amongst all eyes (p=0.04). Eyes with severe VF defects (MD<-10dB) but normal pre-operative RNFL thickness showed a post-operative improvement in MD of 14.6 dB compared to 1.6 dB (p< 0.0001) in eyes with thin RNFL pre-operatively, despite no difference in MD pre-operatively (Normal RNFL MD group = -22.3 dB, Thin RNFL MD = -20.8 dB, p= 0.7).
Conclusion: Persons who have objectively measurable RNFL loss at the time of surgery for chiasmal compressive lesions are significantly less likely to have return of VA or VF after surgery.
Key Words:
neuroophthalmology, optical coherence tomography, automated perimetry, optic nerve, optic neuropathy, optic nerve head
