Evaluation of the Optic Nerve Function in Early Glaucoma Diagnosis. Standard Automated Perimetry (SAP), Short-Wavelength Automated Perimetry (SWAP), Frequency Doubling Technology (FDT), Pattern Electroretinogram (PERG) and Visual Evoked Potential (VEP) in Glaucoma Suspects

Abstract

 

Purpose:

 

to compare the ability of different functional tests in detecting early glaucomatous damage

 

Methods:

 

randomly selected 68 eyes of 68 patients screened by the glaucoma unit of the University Eye Clinic of Pavia were considered glaucoma suspects on the basis of an IOP > 21 mmHg and a morphometric analysis of the optic nerve with confocal laser polarimetry (GDx-VCC) and confocal laser tomography (HRT-III) outside normal limits. They were submitted to SAP (HFA 24-2 SITA-Standard) and divided into two age-matched groups according to Glaucoma Staging System II (GSSII): group A (45 subjects) with GSSII 0 (MD>-2dB, PSD-9.5dB, PSD 1 according to the LOCS III were excluded. The two groups were then submitted to a complete evaluation of the optic nerve function based on SWAP (HFA 24-2 SITA), FDT (N-30), PERG and VEP. Amplitude and latency of P50 and N95 for PERG, and of P100 for VEP, mean defect (MD), pattern standard deviation (PSD), number of points significantly depressed < 5% and < 1% in the pattern deviation plot and test duration for all the perimetric tests and glaucoma hemifield test (GHT) only for SAP and SWAP were compared between the two groups using the Wilcoxon signed rank test.

 

Results:

 

are summarized in the table 1

 

Conclusions:

 

SITA-SWAP can point out early glaucomatous functional damage at least as well as SAP while FDT seems to be less efficient. PERG and VEP were less sensitive. The results might be influenced by the poor number of patients in the group B and by the criteria based on VF outcomes to divide examined subjects.  

 

Keywords: perimetry • electrophysiology: clinical