Correlation between retinal nerve fiber layer thickness and visual field sensitivity: diffuse atrophy imaging study

Area of Science:

• Ophthalmology
• Neuroscience
• Medical Imaging

Background:

• Glaucoma is a progressive optic neuropathy characterized by visual field loss.
• Retinal nerve fiber layer (RNFL) thinning is an early indicator of glaucomatous damage.
• Understanding the relationship between RNFL thickness and visual function is crucial for early diagnosis.

Purpose of the Study:

• To determine the correlation between RNFL thickness and visual field sensitivity in healthy eyes, preperimetric glaucoma, and perimetric glaucoma.
• To quantify functional RNFL loss in eyes with preperimetric glaucoma.

Main Methods:

• Correlation analysis using a simple linear model between optical coherence tomography (OCT)-measured RNFL thickness and standard automated perimetry (SAP) visual field sensitivity.
• Inclusion of 102 eyes with glaucoma and 102 healthy eyes.
• Estimation of functional RNFL thickness by differentiating between functional and residual thickness.

Main Results:

• A strong correlation (R(2) = 0.71–0.77) was observed between RNFL thickness and SAP total deviation.
• Estimated residual RNFL thickness ranged from 50.4 to 56.5 μm.
• Eyes with preperimetric glaucoma exhibited an estimated 37%–41% functional RNFL loss compared to normal eyes.

Conclusions:

• The simple linear model effectively explains the correlation between RNFL thickness and SAP sensitivity.
• Significant functional RNFL loss (approximately 40%) is present in preperimetric glaucoma.
• This highlights the potential for early detection and monitoring of glaucoma progression.