What is lens opacity?

The clouding of the lens is also called cataract. In Germany, the absolutely most common form is age-related lens clouding. Due to a number of factors, such as injuries, diabetes, radiation and mostly age, clouding of the lens occurs.

As a result, vision is significantly reduced. Those affected describe the symptoms as a dense fog that covers the eye. It is possible that the symptoms improve when looking at nearby objects.

The reason for this is that the lens deforms to fix a nearby object. A causal therapy for the disease has not yet been researched, but surgery at an advanced stage can significantly improve vision again. The diseased lens is replaced by an artificial implant.

Surgery on the lens

There are several reasons to perform surgery on the lens. For example, refractive lens replacement can be performed in cases of severe visual impairment. This surgery has the goal of reducing the limitations of severe long or near-sightedness.

As a rule, the operation is performed after the age of 50 or after the onset of presbyopia. The old lens is removed and replaced by an artificial lens. The replacement of the lens, however, leads to a loss of the natural ability to accommodate and for this reason, lens replacement is only recommended if the visual impairment is already present.

The new lens is adjusted to a certain refractive power, mostly for distance vision, and then often has to be accompanied by a supporting visual aid for near vision. In addition to lens replacement in the context of long or near-sightedness, artificial lenses are also used for cataracts. Here, the clouded lens is also replaced by an artificial one.

In order to be able to plan the operation well, a series of examinations must be carried out before the operation. This allows the doctor to decide whether or not it is advisable to replace the lens, as artificial lenses cannot correct all visual defects. A common treatment goal should also be set and it should be clear in advance to what extent additional visual aids (such as reading glasses) will still be necessary afterwards.

The procedure itself is usually performed on an outpatient basis and under local anesthesia. During the operation, the old lens must be removed and the new lens inserted and fixed. To remove the old lens, it is first broken up into small pieces.

This is done with ultrasound and is completely painless. A small suction cup is then inserted through a small opening and the fragments of the old lens are suctioned off. The lens capsule remains intact and can then serve as a holder for the new lens.

The new lens is inserted folded over the same opening and inserted into the capsule. Here it unfolds completely and can thus replace the old lens. It is also possible to use a femtosecond laser to support the incision.

This makes it easier to open the capsule and the cornea. So-called intraocular lenses (IOL) are usually used as lens replacements. The intraocular lens consists of an optical part that replaces the original lens and a holder (haptics) to fix the lens in the eye.

Artificial lenses can be either hard or soft. Hard lenses are made of polymethylmethacrylate.Soft lenses are foldable, which can be advantageous for surgery, and are made of silicone, acrylic or hydrogel. The diameter of the optical zone is usually about 6 mm.

There are different lenses depending on their shape and application. In order to correct visual deficiencies, positive or negative refracting intraocular lenses are usually used. The positive refracting intraocular lens is used to correct farsightedness, while the negative refracting intraocular lens is used to correct myopia.

Multifocal lenses are used to correct presbyopia combined with a pre-existing visual impairment. It is also possible to use an accommodating lens that can mimic the natural accommodation of a lens. In order to improve a visual disorder due to astigmatism, a toric lens can be used.

Toric lenses have a special shape and can therefore compensate for astigmatism. Phake intraocular lenses (PIOL) can also be used as an alternative to intraocular lenses. With Phake intraocular lenses the natural lens is not removed, but the artificial lens is only inserted additionally. These lenses are suitable for the correction of ametropia, but not for cataract treatment.