Abstract
Purpose: :
Optical Coherence Tomography (OCT) is useful in monitoring optic nerve disease. Few studies have looked at the utility of OCT in severe vision loss (SVL) states. Visual acuity in patients with end stage optic neuropathy may be classified using the semiquantitative scale of counting finger (CF), hand motion (HM), light perception (LP), and no light perception (NLP). Patients notice a difference in the ability to perform daily tasks when visual acuity changes at this level (e.g. from CF to HM). Detecting morphologic and perimetric changes among these SVL states is difficult. Correlating peripapillary retinal nerve fiber layer thickness (PRNFLT) with SVL states in patients with optic neuropathies may help determine threshold for change.
Methods: :
A retrospective chart review was performed of patients with a diagnosis of optic neuropathy with a best corrected visual acuity (BCVA) of CF, HM, LP and NLP. Inclusion criteria were a stable BCVA, disease state present for at least one year and previous PRNFLT obtained. Exclusion criteria were a Q number of less than 15 and other pathology affecting PRNFLT results or visual function. Spectral Domain (SD) OCT Mean PRNFLT and quadrant data were analysed with paired T-test and non-parametric Spearman correlation.
Results: :
43 eyes in 40 patients were reviewed. Five eyes were excluded. Of the 38 eyes, 16 had SVL related to glaucoma while 22 had SVL related to nonglaucomatous optic neuropathies. Statistical analysis indicated there was no significant difference in PRNFLT among the four SVL groups.
Conclusions: :
Our small data set suggests no significant difference in SD-OCT PRNFLT among SVL states in end stage optic neuropathy. With severe thinning of PRNFLT, non-axonal content such as glial tissue and blood vessels may be significantly contributing to the measured PRNFLT. Eliminating all non-axonal contributions to PRNFLT on SD-OCT may provide more accurate measurements in severe optic neuropathies.
Keywords: nerve fiber layer • low vision • imaging/image analysis: clinical