The online ad, created by Specsavers' marketing department and online media agency i-level, follows the launch of the brand's 'Postman Pat' TV ad earlier this month, which is aimed at promoting Specsavers' longstanding 2-for-1 campaign.
For today, features the flowing Greendale countryside -- Postman Pat's patch. Users can see the postie driving in his renowned red van, which comes into view over the brow of a hill on the leader board before crashing through a fence.
Pat then disappears behind an ad before accidentally ramming into it from behind, knocking it over towards the viewer as he drives through the page to expose more of Greendale.
After the animation finishes the ad box invites viewers to click through the site at which the TV ad plays above another call for the 2-for-1 offer.
Users will be able to use MSN's services as normal while 'Postman Pat' drives around the screen.
Melissa Milgate, MSN homepage sales specialist, said: "The Specsavers takeover is a great example of the high level of creativity advertisers can achieve if they partner with MSN to launch innovative and engaging formats.
"We chose Specsavers as our partner to test this new format as they are a strong brand in the UK and they were willing to try something new and different."
It will be the second time that MSN's homepage has been transformed for marketing purposes, following a similar takeover by the Harry Potter franchise for the launch of its latest movie this summer.
Richard Holmes, marketing director at Specsavers, said: "'Postman Pat' is an iconic character that all ages can associate with. We had great fun making the television advert and hope everyone enjoys it.
"The opportunity to adapt the animation for MSN seemed a fitting way to launch the online campaign."
The Specsavers 'Postman Pat' ad campaign is supported online via the where a behind the scenes video is available to watch alongside the commercial.
'Postman Pat' is also set to appear on other sites across the web during the next month.
The campaign follows Specsavers' recent 'Thunderbirds' ad, which promoted the optical group's previous 'free reaction lenses' campaign.