An elderly man may have been left blind in one eye after a road rage attack on the M4 in Berkshire.
The 67-year-old man was driving home in his black Mercedes with his 65-year-old wife when a red car struck the front of his vehicle on the westbound carriageway at junction five at about 1820 GMT on Tuesday.
The victim had just turned off from the motorway and was preparing to travel towards Slough.
The red car, possibly a K-registered Vauxhall Astra, stopped and man got out, walked over to the Mercedes and demanded to see the victim's "identity papers".
He then struck the man in the right eye with a broken piece of broomstick causing extensive bleeding.
The couple are Asian but police do not yet know whether it was a racially motivated attack.
Unprovoked attack
The attacker got back into the Astra and drove away towards Slough.
Investigating officer, detective Constable Tripat Pannu, said: "This was a totally unprovoked attack on an elderly man by a person carrying a weapon. The victim may well lose the sight in his eye as a result.
The elderly man, who was in extreme pain, began wandering around the traffic lanes until a couple stopped to help and carried out first aid before calling an ambulance.
He was later taken to King Edward Eye Hospital and underwent surgery the following day.
Police say there is only "5% chance" of his eyesight being saved.
His attacker was white, aged 25 or 26, 6ft tall, of medium build, fair-skinned with short light brown hair, a long thin face and a large nose.
Another man, who was also in the Astra but did not take part in the assault, was also white, aged 19 to 21 and of a larger build.