Evaluation of the optic nerve in early glaucoma diagnosis: standard automated perimetry, short-wavelength automated perimetry, frequency doubling technology, pattern electroretinogram and visual evoked potential in glaucoma suspects

Purpose To compare the ability of different functional tests in detecting early glaucomatous damage Methods 68 randomly selected patients screened by the glaucoma unit of the University Eye Clinic of Pavia were considered glaucoma suspects on the basis of the IOP and the morphometric analysis of the optic nerve with GDx-VCC and HRT-III. They were submitted to SAP and divided into two age-matched groups according to Glaucoma Staging System II: group A (45 subjects, mean age 62±8 y) with GSSII 0 (MD≤-2dB, PSD<2.7dB) and group B (23 subjects , mean age 64±6 y) with GSSII ≤ 2 (MD≤-10dB, PSD≤9dB). The two groups were then submitted to a complete evaluation of the optic nerve function based on SWAP, FDT, PERG, VEP. Number of points significantly depressed <5% and <1% in the pattern deviation plot,MD,PSD, and test duration for all perimetric tests, amplitude and latency of P50 and N95 for PERG and P100 for VEP were compared using the Wilcoxon signed rank test Results All parameters of SAP and SWAP pointed out a good correlation to glaucomatous damage.Only PSD and the number of points <1% were correlated to GSSII in FDT. PERG and VEP outcomes were not correlated to glaucatous damage. Conclusion SITA-SWAP can point out glaucomatous functional damage at least as well as SAP while FDT seems to be less efficient. In perimetric testing the global index PSD seems to be effective in pointing out glaucomatous damage. PERG and VEP are less sensitive but this could be due to the criteria based on VF outcomes to divide examined subjects.