9724
The aims of this study were to determine and rank the frequency of self reported visual disability in daily tasks performed by glaucoma patients ; to examine the interrelation between disabilities using factor analysis ; to study the relation between perceived visual difficulty and a measure of the severity of visual field loss ; to develop a glaucoma specific subgroup of questions ; and examine the validity and reliability of this subgroup of questions .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
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