Korean J Ophthalmol.  2010 Apr;24(2):89-95. 10.3341/kjo.2010.24.2.89.

A Clinical Applications of Photopic Negative Response (PhNR) for the Treatment of Glaucoma and Diabetic Retinopathy

• Kim HD
• Park JY
• Ohn YH

• KMID: 946000
• DOI: http://doi.org/10.3341/kjo.2010.24.2.89

Abstract

PURPOSE
To determine the clinical utility of using photopic negative response (PhNR) by comparing the parameters for normal, primary open angle glaucoma (POAG) and diabetic retinopathy (DR). METHODS: Electroretinography (UTAS E-3000) was performed in 12 normal, 12 POAG, and 12 DR subjects. Amplitudes and implicit times for PhNR were compared among the three groups. The mean deviation (MD) and pattern standard deviation (PSD) were evaluated using standard automated perimetry (SAP). The mean retinal nerve fiber layer (RNFL) thickness and cup-disc ratio were measured using optical coherence tomography. RESULTS: The a-waves and b-waves were not different among the three groups. However, compared to normal subjects, the PhNR amplitudes were reduced, and the PhNR implicit times were prolonged in the POAG and DR patients (p<0.001, p<0.001). The MD and RNFL thickness were correlated with the amplitudes and implicit times for the PhNR. CONCLUSIONS: PhNR may be useful for the detection of inner retinal dysfunction, which is seen in patients who have glaucoma or diabetic retinopathy.

Keyword

Diabetic retinopathy; Electroretinography; Glaucoma; Photopic negative response

MeSH Terms

Adult
Aged
Aged, 80 and over
Diabetic Retinopathy/diagnosis/*physiopathology
Electroretinography/*methods
Female
Glaucoma, Open-Angle/diagnosis/*physiopathology
Humans
Linear Models
Male
Middle Aged
Photic Stimulation
Prospective Studies
Statistics, Nonparametric

Figure

• 

  Fig. 1 Characteristic waveform of a photopic negative response (PhNR). The PhNR is the slow negative potential following the b-wave in photopic electroretinography.

• 

  Fig. 2 (A, B) Comparison of a-waves, b-waves and photopic negative responses (PhNRs) among the three groups. The amplitudes and implicit times of the a-waves and b-waves were not significantly different among the groups. *Amplitudes of the PhNR waves in the primary open angle glaucoma (POAG) and diabetic retinopathy (DR) groups were significantly reduced compared to that of the normal group (p<0.001, Kruskal-Wallis H test). †The implicit times in the POAG and DR groups were significantly prolonged compared to that of the normal group (p<0.001, Kruskal-Wallis H test).

• 

  Fig. 3 The photopic negative response (PhNR) waves from the normal (A) and primary open angle glaucoma (POAG) groups (B). Normal subjects showed normal cup-disc (C/D) ratios and no visual field defects. Glaucoma patients had retinal nerve fiber layer (RNFL) defects, large C/D ratios, and glaucomatous visual field defects. The PhNR waves in POAG patients had reduced amplitudes and prolonged implicit times compared to those of the normal subjects (p<0.001, p=0.006, Mann-Whitney U-test).

• 

  Fig. 4 The photopic negative response (PhNR) waves from a normal (A) and a diabetic retinopathy (DR) patient (B). The normal subject showed normal fundus findings, while the DR patient had evidence of non-proliferative diabetic retinopathy, including multiple retinal hemorrhages and exudates. The PhNR wave in the DR patient had a reduced amplitude and a prolonged implicit time compared to those of the normal subject (p<0.001, p<0.001, Mann-Whitney U-test).

• 

  Fig. 5 Correlations among the photopic negative response (PhNR) waves, mean deviations (MD), and pattern standard deviations (PSD) in the normal and primary open angle glaucoma (POAG) groups. The MD was correlated with the amplitudes and implicit times of the PhNR in POAG patients (A: p=0.027 r2=0.122, B: p<0.001, r2=0.340). However, the PSD had no correlation with the amplitudes or implicit times of the PhNR waves in POAG patients (C: p=0.932, D: p=0.155).

• 

  Fig. 6 Correlations among the photopic negative response (PhNR) waves, mean retinal nerve fiber layer (RNFL) thicknesses, and cup-disc (C/D) ratios in patients with primary open angle glaucoma (POAG). The mean RNFL thickness was correlated with the amplitude and implicit time of the PhNR wave in POAG patients (A: p=0.007, r2=0.157, B: p<0.001, r2=0.391). However, the C/D ratios showed no correlation with the amplitude or implicit time of the PhNR wave in POAG patients (C: p=0.201, D: p=0.073).

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