Use of a blue filter in visual field analysis

Area of Science:

• Ophthalmology
• Visual Psychophysics
• Medical Diagnostics

Background:

• Early detection of glaucoma is crucial for preventing vision loss.
• Standard visual field testing may not always distinguish early glaucomatous changes from normal variations.
• The Friedmann visual field analyser is a common tool for perimetry.

Purpose of the Study:

• To evaluate a modified Friedmann visual field test protocol for improved early glaucoma detection.
• To assess the ability of selective blue field scores to differentiate between normal, ocular hypertension, and early glaucoma groups.

Main Methods:

• One hundred twenty-seven eyes from 127 patients were tested using a Kodak 47B Wratten blue filter with the Friedmann Mark 1 visual field analyser.
• Patients were categorized into normal (49), ocular hypertension (50), and early glaucoma (28) groups.
• A derived threshold value for blue targets (selective blue field scores) was analyzed.

Main Results:

• A simple scoring system did not significantly differentiate the three groups.
• Selective blue field scores successfully differentiated normal subjects from those with early glaucomatous field loss.
• The modified test achieved 64% sensitivity and 96% specificity in detecting early glaucoma, with 22% of ocular hypertension patients showing abnormal results.

Conclusions:

• The adaptation of the Friedmann protocol with selective blue field scores shows potential for enhancing early glaucoma detection.
• This modified approach may assist ophthalmologists in confirming early glaucomatous field defects.
• Further validation is warranted to establish its clinical utility in routine glaucoma screening.