At around the age of 40, when the accommodative power of the eyes noticeably decreases, most people start to have difficulty focusing at close range. A higher dioptric power in the ‘plus’ direction is required to remedy this problem. Single vision lenses can no longer be used for the entire range of vision from far to near.

Bifocal lenses provide clear vision of objects in the distance and near ranges, but everything in between is blurred. Unlike bifocals, progressive lenses provide presbyopia patients with clear vision from far to near and also at every intermediate distance.

The power increase is achieved by a special surface design in which the radii of curvature become increasingly smaller in the vertical and horizontal directions. The range between near and far in which the power rises is known as the progression zone or corridor. This runs downwards in a nasal direction in line with the inward movement of the eyes during convergence.

When the wearer increasingly lowers his eyes for reading, he finds correspondingly higher powers for the required range of vision. The periphery of progressive lenses displays slight areas of blurring which, although they cannot be totally eliminated, have now been reduced to such an extent that they are barely noticed by the wearer.

Zeiss progressive lenses provide:

• Natural vision from far to near;

• Maximum visual comfort due to wider zone;

•Immediate wearer acceptance aided by individualised balancing of all visual zone;

• Individualised design for every patient;

•Optimum cosmetic appearance thanks to thin and light lenses.

All Zeiss Progressive lenses comes with a free Duravision Platinum AR coating. This coating is three times harder than the previous Zeiss coating, and is also dirt-resistant, using an oleophobic coating to aid cleaning along with a super-hydrophobic coat which allows fluid and dirt to bead and roll off the lens.

A blue reflex colour is added to produce 20 per cent less luminous reflectance than conventional green AR coating.