Letterman has been a late-night fixture for 20 years

The 55-year-old star last appeared on his show on 25 February.

During filming of that show he complained about the visible inflammation of his right eye, which turned out to have been caused by shingles - a viral infection related to chickenpox.

Actor Bruce Willis, tennis star John McEnroe and TV personality Regis Philbin filled in as Late Show guest hosts for the rest of that week.

Repeats were aired the following week and a series of additional guest presenters stood in for Letterman on those nights when his show was not replaced by CBS college basketball coverage.

Overall, Late Show ratings during Letterman's absence - his first since recovering from open-heart surgery in 2000 - were mixed.

Lingering pain

CBS are hoping for high ratings on Letterman's first night back, which will feature comedian Billy Crystal and 18-year-old world whistling champion Michael Barimo.

Letterman plans to host all episodes of his show throughout the week.

Swelling around Letterman's eye reportedly cleared up relatively quickly but lingering pain associated with the infection kep him away from work.