Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:The CSC for the visual acuity < 3/60 was 35% in the 1981 NBS [22], 58% in the 1995 survey [24], 85% in an nationwide RAAB survey conducted in 2010 [25], while the CSC of Bhaktapur district in 2006 was reported 90% in BGS [20], Also, the implantation of intraocular lenses in cataract surgery has resulted in better visual outcomes.
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