Shri Kuresha was born in a village called Kooram near Kanchi in A.D 1008. His parents, who were extremely rich, named him Shri Vatsangar. Because of his background he was called Kooranaatha or Kooresha.
When he heard that Shri Ramanuja had joined the monastic order, Kooresha and Dasarathi rejoiced and proceeded to Kanchi, where Ramanuja initiated them into Shri Vaishnavam, by performing Pancha-samskaram. Kooresha and Dasarathi were the first disciples of Ramanuja. It is believed that both Dasarathi and Kooresha are the incarnation of the divine symbols of Lord Vishnu, namely, the Conch and the Discus respectively.
After studying under Ramanuja for a while, Kooresha returned to Kooram. There he was very generous with his wealth and used to feed and cloth anyone who came at his door. It is said that the doors at his mansion would close only after the doors at Kanchi Varadaraja Perumal Temple closed.
One day the doors at his mansion closed earlier than usual. The next day, Kanchi Poorna visited him inquiring about the reason for closing his mansion's doors before Shri Varadaraja's doors closed and added that it was the Lord's wish to get an answer from him. On hearing that the noise from his mansion's doors disturbed the Lord, he resolved to forego all his possession and join Ramanuja at Shri Rangam.
Soon Kooresha and Andaal (his wife) were on their way to Shri Rangam. They were walking through a thick forest, which Kooresha's wife was not used to. Soon she stopped Kooresha and asked him if the path they had taken was safe. To this, Kooresha replied, there was no reason to be afraid as long as they do not have anything of value with them. Saint Andaal replied that she had brought a small cup made in gold to fetch water for Kooresha. He immediately took the cup and threw it away, saying her fears has been defeated. When they arrived at Shri Rangam, Ramanuja invited them with a warn reception. Kooresha and Andaal then made Shri Rangam as their home.
Kooresha assisted Ramanuja in writing the Shri Bhasya. It is said that, he accompanied Ramanuja to Kashmir and studied Bodhayana-vriti; a gloss on the Brahma-sutras, which was available only there. He committed the entire text to memory when the authorities in charge of the manuscript did not permit Ramanuja to take it with him. He helped Ramanuja in writing the Shri Bhasya by reciting the relevant passages of the Vritti.
When Ramanuja was ordered by Kulottunka to appear before him and admit Shiva's supremacy, Kooresha feared for Ramanuja's life. He convinced Ramanuja to switch robes and appeared before the king in Ramanuja's ascetic robes. He lost his eyes when he was not able to create conviction in favor of Vishnu in the mind of the King. His devotion to the Lord was such that he was able to visualize the divine vision of Lord Varadaraja at Kanchi and describe Him to Ramanuja.
Kooresha and Andaal had two sons, Parashara Bhattar and Vedavyasa Bhattar, who became great scholars during their times. Kooresha composed five poems, collectively known as Panchasthavam, in addition to some Granthas. The five poems are:
Shri Vaikuntha Stava
Shri Atimaanusa Stava
Shri Sundarabaahu Stava
Shri Varadaraaja Stava
Source : http://www.Shrivaishnava.org/sva/koor.htm