Decreased contrast sensitivity in normal tension glaucoma determined by pattern visually evoked cortical potentials

Area of Science:

• Ophthalmology
• Neuroscience
• Visual Science

Background:

• Normal tension glaucoma (NTG) is a form of glaucoma where intraocular pressure is within the normal range.
• Central visual function, particularly contrast sensitivity, is not well understood in NTG patients.
• Early detection of visual field defects is crucial for managing glaucoma progression.

Purpose of the Study:

• To investigate the central visual function, specifically contrast sensitivity, in patients with normal tension glaucoma (NTG).
• To evaluate the utility of pattern visually evoked cortical potentials (PVECPs) as a sensitive tool for detecting visual abnormalities in NTG.

Main Methods:

• Contrast sensitivity was assessed in NTG patients and normal subjects using pattern visually evoked cortical potentials (PVECPs).
• PVECPs were recorded with a checkerboard pattern reversal display (15' and 60' check sizes) at 3 reversals per second, with contrast varied across 7 steps.
• Contrast thresholds were calculated based on regression analysis of peak latency at different contrast levels.

Main Results:

• A significant delay in the P100 component of PVECPs was observed in the NTG group for the 60' check size across all contrast levels (P < 0.05).
• The contrast threshold was significantly increased in NTG patients for both tested check sizes (P < 0.05).
• These findings indicate a reduced contrast sensitivity in individuals with NTG.

Conclusions:

• Contrast sensitivity is demonstrably decreased in patients with normal tension glaucoma (NTG).
• Pattern visually evoked cortical potentials (PVECPs) serve as a sensitive method for identifying functional visual impairments associated with NTG.
• PVECP testing can aid in the early detection and management of NTG.