Short Duration Transient Visual Evoked Potentials (SD-tVEP) in Unaffected Fellow Eyes of Unilateral Exfoliation Syndrome and Exfoliative Glaucoma Patients

Abstract

 

Purpose

 

To compare the fellow eye of unilateral exfoliation syndrome (XFS) and exfoliative glaucoma (XFG) patients SD-tVEP test results to a set of SD-tVEP parametric reference ranges.

 

Methods

 

The study population was divided into two groups: 1) 24 fellow eyes of 24 unilateral XFS patients (70.0±7.0 yr); and 2) 33 fellow eyes of 33 unilateral XFG patients (71.0±8.1 yr). The fellow eye of the XFG patients did not have clinically evident XFS. The non-exfoliative eye (fellow eye) and exfoliative eye of unilateral XFS and XFG patients had a visual acuity of 20/50 or better. Low Contrast (Lc) and High Contrast (Hc) SD-tVEP’s were recorded using the Diopsys NOVA System (Diopsys, Inc. Pine Brook, NJ). The Michelson contrast of the Lc and the Hc SD-tVEP stimuli were 15% and 85%, respectively. All stimuli was a counterphased modulated checkerboard pattern. The fellow eye’s SD-tVEP responses were compared to four age adjusted SD-tVEP reference ranges,which were established in conformance to the FDA suggested Royston method.. The reference ranges are for the following SD-tVEP’s parameters: Hc N-75-P100 amplitude; Hc P100 latency; Lc N75-P100 amplitude and Lc P100 latency.

 

Results

 

13 of the 24 fellow eyes of the unilateral XFS patients produced SD-tVEP responses outside of at least one of the four SD-tVEP 95%CI reference ranges. 6 eyes failed on one parameter; 4 eyes failed on two parameters and 3 eyes failed on all four parameters. 23 of the 33 fellow eyes of the unilateral XFG patients produced SD-tVEP responses outside of at least one of the four SD-tVEP 95%CI reference ranges. 9 eyes failed on one parameter; 7 eyes failed on two parameters; 5 eyes failed on three parameters and 2 eyes failed on all four parameters. Table 1 shows the SD-tVEP’s parameter’s distribution of the parameters that were outside normal llimits for the XFS and XFG patients.

 

Conclusions

 

The Short-duration transient VEP was capable of identifying abnormal visual functions in a majority of the fellow eyes of unilateral XFS/XFG patients.  

 

Table 1. Distribution of SD-tVEP parameters outside reference range limits.