The company that makes the highest quality eyeglass lenses is Essilor.
Essilor is considered the world leader in eyeglass lenses and are known for their progressive lenses which include Varilux and their lens coating, Crizal.
Essilor also uses innovative technology and craftmanship.
Zeiss is also another company that makes high quality eyeglass lenses and they are known for their premium lenses, including their progressive eyeglass lenses and they're also known for their clarity, comfort and durable coatings.
Rodenstock is a German manufacturer of eyeglasses and lenses and are known for their precision, clarity, and innovative technologies and are also known for their single vision, progressive and specialty lenses.
Hoya is known for their durable coatings and high index technology and are known for their progressive eyeglass lenses including Hoyalux.
The reason why prescription eyeglasses are so expensive is because they have high retail markups as well as the cost of specialized materials needed to make the prescription lenses and the manufacturing process as well as the limited competition.
Retailers of prescription eyeglasses and contact lenses often mark up the cost of the frames and lenses which contribute to the overall price and they know they can get away with it because people need the glasses and contact lenses.
The eyeglasses and eyewear industry is also dominated by a few major players, which too can lead to the higher prices and less price competition.
Also a single company, called EssilorLuxottica, controls a large portion of the eyewear market, and owns many well known brands and retail chains.
Eyeglasses are also made from various specialized materials, including durable and lightweight options such as titanium as well as acetate for frames and lenses with specialized coatings for scratch resistance, anti glare and UV protection.
Also creating or making prescription lenses for eyeglasses requires a high level of precision and customization, especially for complex prescriptions like progressive lenses which also adds to the cost of the eye prescription or eyeglasses.