Ability of Spectral-Domain Optical Coherence Tomography to Predict Humphrey Visual Field Defects in Patients With Open-Angle Glaucoma

Friday, April 25, 2014
KIOSKS (Boston Convention and Exhibition Center)
Andrew K. Salem, MD, Tulane University, New Orleans, LA, USA
Mathew K. George, MD, Sakowitz Eye Center, Orange City, FL, USA
Ramesh Ayyala, MD, FRCS, Tulane University, New Orleans, LA, USA

Narrative Responses:

Purpose
To investigate the ability of clock hour measurements of neuro-retinal rim (NRR) thickness and retinal nerve fiber layer (RNFL) thickness using Cirrus HD Spectral-Domain Optical Coherence Tomography (OCT) to predict the pattern of corresponding humphrey visual field (HVF) defects in patients with open-angle glaucoma.

Methods
Retrospective, single-center chart review of patients with open-angle glaucoma who had both an optic nerve head (ONH) analysis measured by Cirrus HD SD-OCT and a HVF within 3 months between September 2011 and March 2013. A total of 33 eyes of 26 patients were included, as well as 30 control eyes. Glaucomatous visual field defects were defined by a standard criteria, confirmed by a minimum of two reliable tests (false positives <15%, FN <15%, fixation loss <20%), and categorized into three groups: superior field defects only (n=18), inferior field defects only (n=6), and miscellaneous (n=9) field defects.

Results
Patients with superior visual field defects had statistically significant NRR thinning at all clock hours vs. controls (p<0.0001 for all clock hours).  Patients in the inferior visual field defects group had significant NRR thinning compared to controls from clock hours 11 to 1 (p= 0.02, 0.03, and 0.04 respectively) and clock hours 6 and 7 (p=0.03 for both).   Neither group showed preferential localized thinning at the clock hours of the corresponding visual field regions as designated by structure/function correlation maps (‘Garway-Heath Map’) compared to non-corresponding areas.

Conclusion
Previous studies have shown that clock-hour neuro-retinal rim assessment using Cirrus HD-OCT may enhance glaucoma diagnostic ability.  However, while NRR clock-hour measurements are helpful in predicting whether or not a glaucoma patient will have a visual field defect, they do not appear to reliably predict the type of defect.