Cataract

The cataract [ ˌ kataʁakt ] or cataracts refers to a clouding of the eye lens. Looking at people who are suffering from advanced cataracts, you can see the gray color behind the pupil, where the term cataract is derived. The clouded lens can be surgically replaced in most cases by an artificial lens implant.

Word origin

The grammatically masculine word cataract means " waterfall " or an articulated by blocks or rock formation, " rapids " and is in German since the 16th century detectable. Specially designed for medical contexts retained the borrowed word as part of the language of the learned grammatical gender of female Latin form of cataract, which in turn is the Greek of the ( male ) nominalization καταρράκτης ( ancient Greek pronunciation Katarraktes ), down tumbling ', this καταρράττειν to Attic, katarrháttein, fall down ', was borrowed.

Demarcation

" Cataracts " is not to be confused with the "Green Star" ( glaucoma), a number of eye diseases of a different origin (see Star ( Ophthalmology) ).

History

In ancient times, people assumed in the development of cataracts would (in the sense of the Hippocratic - Galenic humoral pathology ) substances flow down behind the pupil, as the visual impression of the person concerned a look through a cascading waterfall resembled. The term star is already in the 8th century in the German present and refers to the " freezing " of the charge included mass, which can then be cured by surgery. Another explanation derives the term from the verb " stare " from, which the person concerned is to be described as " with open eyes blind".

Already in pre-Christian times tried to cure cataract surgery. From Babylonian times the star stitch is known. Derived from the phrase " someone the star sting " meaning " someone reveal the truth to enlighten someone about something ."

An overview of the history of surgical therapy in the 18th and 19th centuries wrote of the Swiss ophthalmologist Alfred Bader.

Symptoms

The main symptom is a slow, painless loss of vision (visual acuity ), especially if the onset of turbidity is in the central regions of the lens. This leads to blurred vision and increased glare sensitivity because a diffuse light refraction produced by the lens opacity. Also reduces the perception of contrasts, allowing patients their environment " as through a fog " perceive.

Occasionally, monocular diplopia, are still present during the closing of the healthy eye. It can be observed around light sources halos or halos. The light-dark adaptation of the eye is slowed, and the ability to see spatially may be impaired.

In rare cases, it may occasionally cause a temporary improvement of vision at close range. Here, the thickening of the lens and the compression of the lens nucleus cause an increasing " myopic shift " (change in refractive power towards a near-sightedness). This improvement is, however, offset by a corresponding deterioration of visual acuity. Moreover, this condition is often short-lived because of the increasing opacity of the lens decreases the visual acuity at all distances.

Causes and epidemiology

• <90
• 90-180
• 180-270
• 270-360
• 360-450
• 450-540
• 540-630
• 630-720
• 720-810
• 810-900
• 900-990
• > 990

The cause of cataracts is often unknown. It usually only occurs in old age, but can develop earlier already. The typical " senile cataract " is formed from over the years, sometimes in a few months. Especially in African countries but already many children are affected by the disease due to malnutrition.

Ionizing radiation, in particular UV radiation can damage the lens of the eye and thus favor the development of a cataract. Diabetes mellitus, reactions to drugs (especially cortisone), drugs or trauma also are a possible cause question. Smoking can also develop a cataract favor. Stopping smoking can be seen in the long term reduce the need for surgery, especially in male smokers, but not reduce the overall risk of disease a person. Likewise, vitiligo (white spot disease ) cause cataracts. Increased cataract formation is also observed in bullous ichthyosis Siemens.

Stark effect of current and lightning can cause cataracts. A caused by infrared radiation cataract (Fire Star, Star heat or glassmakers Star ) in occupations where very hot materials are processed ( blast furnace workers, glass blowers ), is recognized as an occupational disease.

Rubella during pregnancy can cause a cataract in the newborn be ( congenital rubella syndrome ). Even when Galaktokinasemangel can a congenital cataract occur. In cases of congenital cataracts, the cloudy lens must be removed surgically from his expression because of the risk of being amblyopia in infancy depends.

During the formation of a cataract, the lenses have to be adjusted due to the changing refractive power of the eye frequently. The patient feels mitigation of visual acuity with optimal correction as disturbing and intolerable, as an indication for surgical removal of the lens and its replacement is given by an artificial implant. Conservative treatment of cataracts is not known. The surgery is usually performed on an outpatient basis, in the presence of additional risks and stationary. A long delaying a necessary operation has no advantages or disadvantages. However, in general, the lens is increasingly harden, so that their removal is difficult and therefore risky.

Classification

In general, the cataract is classified according to the localization of the turbidity.

In the cortical cataract, clouding in the lens cortex by so-called water column (ie, fluid-filled vacuoles ). Approximately 50% of senile cataracts begin with this lesion.

The cataract subcapsularis posterior ( posterior subcapsular cataract ) accounts for about 20% of senile cataracts. It proceeds rapidly, it comes early to vision problems, especially when near vision.

The nuclearis cataract (nuclear cataract ) is slowly progressive. It comes to a brownish haze and an increase in the refractive power. Was a patient previously altersweitsichtig, so now it can be a temporary improvement in visual acuity in the vicinity which can make reading glasses for a certain period unnecessary. In the course of monocular diplopia may occur.

Surgical Treatment (cataract surgery)

Each year, carried out in Germany over 650,000 operations in which the clouded lens is replaced with an artificial lens implant. They are among the most performed surgical procedures in general. Until a few years ago was considered a significant indication for cataract surgery significantly reduced visual acuity to about 0.3 and worse. Today also subjective impairment of the patient as widely recognized increased sensitivity to glare or degraded night vision than sufficient reason to make an appropriate intervention. This puts the not infrequent in the public discussion view, surgical procedures were often carried out without sufficient medical reasons and primarily for economic reasons.

Failure to perform cataract surgery at existing restriction of vision could not only reduce the quality of life, but also increase mortality. At least this was an Australian study in which two groups were examined, which had operations or the operation refused. At first glance, the differences were small, but on account of age, anything else health, lifestyle and much more significantly increased mortality was observed in those who did not let the cataract surgery perform despite restriction of vision. Causes of the increased mortality could increased risk behavior at a lower quality of life, represent errors in the medication and falls.

Anesthesia

In the vast majority of cases, cataract surgery is performed under local anesthesia. Through an injection anesthesia in which the anesthetic is next ( " Peribulbäranästhesie " ) or after ( " retrobulbar " ) injects the eyeball, the eye in the ideal case is not only completely free of pain, but also can not be moved actively. In a topical anesthesia in which the anesthetic is dripped onto the surface of the eye, complete freedom from pain is also achieved, the patient must, however, be able to depends on the experience of the surgeon, for the duration of the operation - straight more or less quiet - about 10 minutes to look. Accordingly, this method is not suitable for every patient.

A cataract surgery under general anesthesia ( general anesthesia ) is displayed ophthalmologist hand rare. Many a surgeon preferred this method when the only seeing eye is ( "last eye") operated to thereby ensure ideal conditions for a safe and uneventful surgery. In patients with involuntary movements (eg Parkinson's disease or Restless Leg Syndrome ) or mental disorders, a general anesthetic the procedure sometimes possible at all. Other reasons may be foreseeable intraoperative difficulties that might force them to an extension of the procedure. Often, however, it is the wish of patients, which leads to an operation in anesthesia. The anesthetic and operative procedure must be discussed with the patient preoperatively in detail as a function of previous and concomitant diseases of the eye, previous surgeries and any anticipated risks and complications.

Technology

There are two different approaches:

After surgery, the operated eye is covered with a bandage, which is first removed with no complications the next day for a short time. The first impression of most patients is that they are much stronger than predicted colors and the overall image is brighter until a slight glare. Depending on the choice of the artificial lens is then followed by the realization that you see either near (hands) or distance without glasses sharp.

Use of artificial lenses

Without a lens implant (called intraocular lenses ), one would perceive the world blurred because the eye would be about 16 to 18 diopters farsighted. Such a Linsenlosigkeit ( aphakia ) can with a contact lens or - in appropriate cases - even by a subsequent (secondary) artificial lens implantation can be corrected. So-called Star Glasses are rare and only then be considered if other methods are not feasible.

After removal of the natural lens of the eye can no longer adapt to diverse Sehdistanzen ( accommodate ). Therefore a pair of reading glasses is for reading, as in the case of presbyopia ( presbyopia ), is required. Especially for young patients who still had to surgery for a full accommodation power, is the loss of quite a reduced quality of life dar. subject of the present research are therefore to an artificial lenses that are intended to replace a certain accommodation ability of the eye. The results so far are to be assessed cautiously. Multifocal intraocular lenses provide the opportunity to lead a " life without glasses " when the disadvantages in the form of weak double vision and a depreciation of contrast sensitivity are taken into account. Secondly, by appropriate choice of lens implants a condition of anisometropia be brought about, the one that allows the eye, in the distance to see clearly, and the other near ( monovision or Goetheblick ). However, this is no binocular and stereoscopic vision is thus possible.

With the onset of intraocular lenses opens up the opportunity to correct refractive errors ( ametropia ). This is an additional advantage of high refraction values ​​. In severe cases, however, it is most essential from a medical perspective, both eyes to operate in quick succession, as from an anisometropia ( difference between the total refractive power of both eyes ) of about 3 diopters is expected to complaints. The patient must decide whether he wants to live according to the procedures without distance glasses, but with a pair of reading glasses, or vice versa, so that the appropriate strength of the artificial lenses can be selected before the operation. If both eyes require surgery, should the interventions at a distance of a few weeks, in individual cases, perform a few days. Antibiotic and anti-inflammatory eye drops are Postoperatively, for about three to four weeks, depending on the healing process and applied two, three or performed more ophthalmological controls. After the second operation, it takes again up to eight weeks until the healing process is now complete and a stable situation has been established, which allows for adaptation of new lenses.

A new method of cataract surgery is the insertion of the so-called light - adjustierbaren lens ( LAL). In this lens can be adjusted according to the operation by irradiation with UV light, the refractive power.

Complications

The complication rate for cataract surgery today is relatively low, especially since this is the most commonly performed surgical procedure in humans at all. As complications during cataract surgery intraocular infections (infection inside the eye ), breach of only a few micrometers thick posterior lens capsule with subsequent vitreous prolapse, one occurring after days to weeks swelling of the central retina ( " cystoid macular edema " ) with accompanying visual loss and as a late consequence of a slowdown in the rear lens capsule ( " PCO " ) occur. It is controversial whether the risk of subsequent retinal detachment after ( without complications ) Cataract surgery is significantly increased.

Cataract

As a result of cataract surgery, there may be formation of an opacification of the posterior lens capsule with a corresponding decrease in vision. This so-called secondary cataract ( secondary cataract ) previously developed in up to 50 % of the operated eyes. Modern lens designs and surgical procedures have the PCO, however, on average, reduced to less than 4 %. It is an opacification of the posterior capsule of the lens, either as a result of conversion of the fibrous capsule ( fibrotic form) or by replication and spreading of remaining at the surgical lens cells on the capsule ( regeneratorische form). After pharmacological dilation of the pupil ( mydriasis), the posterior lens capsule with multiple pulses from a Nd: YAG laser and opened the turbidity by a Nd: YAG laser capsulotomy on an outpatient basis and painlessly eliminated. Risks and complications of this treatment is relatively low.

Veterinary Medicine

Even in animals of the operational replacement of clouded lenses is possible with an implant and for years in many cases, treatment of choice. At the Faculty of Veterinary Medicine of the University of Wisconsin -Madison, cataract surgery was performed, for example, in a blind owl.