The photopic negative response as a promising diagnostic tool in glaucoma. A review.

PURPOSE: Based on the available literature, the clinical usefulness of Photopic Negative Response (PhNR) of flash Electroretinogram (ERG) in detecting glaucoma has been described.

MATERIALS AND METHODS: Data published in the literature available at the Pub Med library between 1999-2011. Different techniques of eliciting, assessing and measuring PhNR have been analyzed. Relations between results of static automated perimetry (SAP), Gdx, optical coherence tomography (OCT), pattern electroretinogram (PERG) and PhNR in glaucomatous patients have been described.

RESULTS: 1. The most frequent method of PhNR recording has been brief (< 6 ms), red stimulus against the blue background with thread active DTL electrodes. 2. There has been a significant decrease of PhNR amplitude and PhNR/b-wave ratio in patients with different stages of glaucoma field defect. 3. Curvilinear and linear correlation between retinal sensitivity (SAP), retinal nerve fibre layer thickness (RNFLT), PhNR amplitude and PhNR/b-wave ratio has been found. 4. A significant correlation occurred between PhNR and PERG amplitudes. 5. Focal PhNR seems to be a more specific and sensitive tool in comparison to full field PhNR.

CONCLUSIONS: PhNR is a promising tool in glaucoma neuropathy assessment. Up to date the value of PhNR has not been definitely proved. More research is necessary to con rm the usefulness of PhNR in diagnosing glaucoma.