Boots Opticians is to merge with Dollond & Aitchison, the high street retail chain said today.
The combined business, trading as Boots Opticians, will have around 690 practices and employ more than 5,000 staff.
Dollond & Aitchison will gradually disappear from the high street as its stores adopt the Boots Optician brand.
Alliance Boots said the new company, which will be joint-owned with Dollond & Aitchison parent De Rigo, will create the UK's second largest chain of opticians.
The new Boots Opticians is expected to knock Vision Express off second place in the UK's optical chain pecking order.
Specsavers will still be the country's largest opticians.
Boots Opticians will be run as a stand-alone business and it is expected that the headquarters will be established in Nottingham.
Stefano Pessina, executive chairman of Alliance Boots, said: "The merger gives us an excellent opportunity to create a leading force in the UK optical market.
"Our plan is to grow and develop the new business, building on the strengths of the Boots brand."
The deal, which is subject to the approval of competition authorities, is expected to be completed by the end of June.
Alliance Boots will hold a controlling stake in the new company.
The firm said it hoped the new Boots Opticians would use De Rigo's strength as a glasses designer.
Maurizio Dessolis, vice chairman of De Rigo, said: "The proposed merger will bring together many complementary strengths.
"The new business will offer customers excellent service and high-quality eyewear."
Boots Opticians employs 2,800 people, while Dollond & Aitchison has 2,200 workers.
A spokeswoman for Alliance Boots said neither company had full coverage in the UK, so it was anticipated that there would not be much overlap.
She said the merger was motivated by a desire "to grow the business" rather than out of any financial worries on either side.
"The idea is really to create a leading force in the optical market," she added.