[Measurement of glaucoma-specific functionality with the GQL-15 and correlation with parameters of visual function]

Area of Science:

• Ophthalmology
• Quality of Life Research
• Psychometrics

Background:

• Glaucoma is a leading cause of irreversible blindness globally.
• Patient quality of life and vision-related functioning are significantly impacted by glaucoma.
• The Glaucoma Quality of Life 15 (GQL-15) is a disease-specific tool for assessing glaucoma-related functional impairment.

Purpose of the Study:

• To evaluate the German version of the GQL-15 questionnaire.
• To assess the correlation between GQL-15 scores and perimetric parameters in glaucoma patients.
• To determine the psychometric performance of the GQL-15.

Main Methods:

• A German version of the 15-item GQL-15 was developed and administered to 98 glaucoma patients.
• GQL-15 results were correlated with mean deviation (MD) and pattern standard deviation (PSD) from visual field tests.
• Classical and Rasch model analyses were performed to evaluate test properties.

Main Results:

• The mean GQL-15 score was 77.3 ± 21.7.
• Most GQL-15 items showed significant correlation with the MD of both the worse (r=-0.416) and better (r=-0.304) eyes.
• A strong correlation was observed between glaucoma-specific quality of life and visual acuity.
• A nine-item short version demonstrated superior psychometric performance.

Conclusions:

• The German GQL-15 is a valid instrument for assessing vision-specific functional impairment in glaucoma.
• GQL-15 scores correlate more strongly with the visual sensitivity of the more severely affected eye.
• Findings aid in understanding individual patient impairment to enhance glaucoma management and patient counseling.