Cataract (cataract): causes, symptoms, treatment


Cataract (cataract) is a disease of the eye lens in which it gradually becomes clouded by an increase in fiber material and water inside the lens. In most cases, the cataract occurs from as yet unexplained causes in older age. But also metabolic diseases such as diabetes mellitus or eye injuries can cause a cataract.

Everything is blurred and colorless

Due to the gradual compaction, the eye lens not only clouds but also loses its elasticity. As a result, light entering the eye can no longer penetrate unhindered to the retina and, in addition, is broken differently than before.

The result is a blurred, colorless image with washed out contours and a contrast reduction. Often there is still an increased dazzling sensation, which is perceived as particularly disturbing when driving at night.

Easy to diagnose

In order to diagnose cataracts, a series of examinations that can be carried out easily with every ophthalmologist visit are generally sufficient.

Before each examination there is an anamnesis interview, in which the attending physician asks for prevailing complaints. Subsequently, in case of a suspected cataract, a vision assessment test and a slit lamp examination are performed. This allows an evaluation of the lens. Further investigations may follow if there are risk factors for other diseases.

Cataract surgery: a standard procedure

If the diagnosis is cataract, it can be attempted in the beginning stage to compensate for defective vision with glasses or contact lenses. If the lens dizziness progresses, the only effective treatment option is an operation. There is no medical cataract therapy.

The cataract operation is one of the most commonly performed procedures in Germany at all. It is associated with comparatively few risks and complications and leads to a significant improvement in vision in more than 95%. As part of the operation, the clouded lens is removed and replaced with an artificial lens. The procedure can be performed on an outpatient basis under local anesthesia.


Cataract (cataract) is a disease of the eye lens, which causes an increase in cloudiness. The term is used as a collective term for any form of lens opacification, regardless of how it originated. Typical for the cataract is a gray discoloration of the usually black appearing pupil, which was eponymous for the disease.

A disease of old age

The cataract can occur for many different reasons, but the highest case numbers are observed in old age. With increasing age, the prevalence of the disease increases in the population. While around 15% of men and 25% of women are affected between the ages of 65 and 75, the number rises to 40% for men after age 75 and to about 45% for women.

In the industrialized nations, about one in three subjects today undergo up to fourth of a cataract operation, which makes about 7 operations per 1000 inhabitants. In Germany alone around 800,000 star operations take place annually.

In contrast, in developing countries, where surgical therapy for cataracts is not yet established, cataract remains one of the leading causes of blindness.


The eye lens is an essential part of the optical system. It is of biconvex shape and lies in the anterior third of the eye, behind the horn and iris, and in front of the vitreous and retina. In particular, the cornea and lens break the light entering the eye and focus the individual rays of light at a point on the retina, the so-called fovea point. There, a sharp image is created, which is transmitted to the brain via the optic nerve.

The sharpener

The lens has a very special function. By changing their shape (rather flattened or rather spherical), the view into the near and far can be focused.

For this purpose, the lens is attached via fine fibers and ligaments in the middle of an annular muscle.When the muscle relaxes, it pulls on the so-called zonular fibers, which connect the muscle and the lens, and the lens becomes flatter. Conversely, when muscle contraction occurs, the inner diameter of the circular muscle decreases, the zonular fibers relax, and the lens assumes a more spherical shape.

When cataract, the lens loses its elasticity and becomes more rigid. Defective vision in the distance as well as in the vicinity are the result.

to form

The cataract can arise at different areas of the eye lens. Depending on where it manifests, three forms are distinguished:

  • Bark Star: affects the outer edge of the eye lens
  • Core Star: affects the center of the eye lens
  • Rear cup haze: affects the posterior outer area of ​​the eye lens
  • mixed forms

In some cases, it may be inferred from the location of the haze that there is a possible cause for cataract formation. Thus, the old-age star often begins with a turbidity of the bark, while a longer-term intake of Cortisone rather leads to a rear cup clouding.


In addition to the various forms of cataract, there is a staging, with which the degree of lens opacity can be further estimated.

  • Stage 1 -Cataracta incipiens : At the onset of lens opacity, there is only a slight change in the eye lens, the vision is not or only slightly limited. An operation is not necessary at this stage. It can be first waited.
  • Stage 2 -Cataracta provecta: The lens is progressively clouded, the visual acuity is reduced. Since the symptoms of cataract at this stage lead to restrictions in everyday life, is already advised in stage 2 to cataract surgery.
  • Stage 3 -Cataracta matura: The third stage of cataract is also referred to as a mature cataract or totalstar. The lens is completely clouded at this stage and already appears gray through the pupil. Since vision is now severely limited, there is always a clear indication for surgery.
  • Stage 4 -Cataract intumescens: In overripe cataract, in addition to complete clouding, significant fluid retention occurs as the lens swells. Since cataract stage 4 represents a strong risk factor for the development of glaucoma, immediate surgery is required. Last but not least, to preserve the eyesight.

In a far advanced cataract, the otherwise black appearing pupil appears gray clouded. In a total star, so a star that covers the entire lens, it comes to blindness. The pupil appears empty and clearly gray.


The cataract can have many different causes. In the majority of cases, it arises in the context of the normal aging process, which leads to an increase in the lens substance as well as loss of water and elasticity of the lens, so that it can no longer fulfill its normal function.

Smoking and other risk factors

A safe risk factor for the development of a cataract in old age is smoking. Even with 10 to 15 cigarettes a day, the risk of developing cataracts increases by about 40% compared to a non-smoker.

Furthermore, a cataract can go back to other, acquired causes. These occur with a total of about 10% much rarer than the natural process in old age, but should not be ignored.

The most common are the following causes:

  • General disorders: diabetes mellitus, dialysis-dependent renal insufficiency, Wilson's disease, galactosemia, trisomy 21
  • previous eye diseases: chronic inflammation in the eye (uveitis), glaucoma (especially acute angle-closure glaucoma), retinal detachment, diseases of the vitreous or the retina
  • Medicines: local or systemic cortisone preparations, drugs to dilate the pupil (miotics such as cholesterol esterase inhibitors)
  • previous traumas: bounce or perforation injuries
  • physical: X-ray or radioactive radiation, high-voltage accidents, lightning, infrared radiation (so-called Feuerstar, especially in blast furnace workers and glassblowers)
  • previous lens surgery: After cataract surgery, the remaining lens parts can become cloudy (post-star).

Rare: congenital cataract

A cataract does not always appear in the course of life due to endogenous or exogenous causes. Congenital cataract, which accounts for less than 1% of all cataracts, causes eye disease in the womb.

The congenital cataract may be due to genetic factors or consequence of a disease of the mother during pregnancy. For example, rubella, which is transmitted from the mother to the unborn child in the prenatal state, can lead to cataract.

Read also:
Cataract: basics and causes


A creeping process

The symptoms that can occur in a cataract, depend on different factors.Especially the shape and severity of the cataract are decisive for the symptom severity. Occurring visual impairments arise creeping over months or even years away.

Typical of the cataract include:

  • double vision
  • blurred vision
  • Difficult seeing in the dark or at dawn
  • reduced contrast perception
  • reduced color perception
  • increased glare sensitivity
  • Deterioration of spatial vision
  • reduced light-dark adjustment when switching from light to darker places

Not all complaints are always the same. Which symptoms are in the foreground depends on the one hand on the stage of the disease; on the other hand, there are differences in vision depending on which star shape it is.

Strong glare on the bark star

The classic age star in most cases begins at the bark of the eye lens and spreads from there gradually over the entire lens. It becomes symptomatic only when central areas of the lens have been detected by the star.

The bark star is initially mostly by an increased glare sensitivity with decreasing color intensity. Especially evening driving or the time of dusk can be uncomfortable, because oncoming cars dazzle very much, but the environment can be perceived significantly less contrasted and thus much worse.

Myopia at the core star

In the case of the core star, which manifests itself mainly or exclusively in the center of the lens, especially the vision in the distance is impaired. A typical feature of a core star is the change from far-sightedness to myopia. But the occurrence of double or even multiple images is a typical sign of a beginning core star.

Farsightedness in the posterior cup haze

In the posterior buccal clouding, also called subcapsular bark obstruction, there is mainly a limitation of vision in the vicinity and an increased glare sensitivity. The posterior shell turbidity occurs especially in old age, but also associated with poorly controlled diabetes mellitus.


Your treating ophthalmologist can usually ensure the diagnosis of cataract by the synopsis of a targeted survey (anamnesis) as well as various ophthalmological examination results. The most important component of ophthalmic examination methods is the slit lamp examination, followed by further tests, which measure visual acuity, for example.

1. Anamnesis

Anamnesis aims to pinpoint your symptoms. In a doctor's consultation you will not only be asked which symptoms you have, but also how long they have already existed and in which situations they occur especially, or if there are situations in which you feel that the symptoms have improved.

Furthermore, it will be of interest to your treating ophthalmologist whether you suffer from pre-existing conditions such as diabetes mellitus, high blood pressure or heart disease and how well these are adjusted.

2. Slit lamp examination

After the anamnesis interview, the slit lamp examination takes place. It is the gold standard for examining and evaluating the lens of the eye, as it allows up to forty times the size of the anterior segment of the eye.

Harmless investigation

During the examination, you sit on a height-adjustable stool facing the doctor and support the chin and forehead with the devices provided for this purpose. During the examination, you have to keep your head still, and the attending physician can then accurately position the slit lamp and begin the examination.

With the slit lamp especially the front sections of the eye are examined for abnormalities and assessed. This includes:

  • Conjunctiva
  • Cornea (cornea)
  • Regenskorgenhaut (Iris)
  • Lens

The cornea under the magnifying glass

The cornea is the first section of the optical system to be viewed and evaluated. As a convexly curved, transparent layer, the cornea has the function of breaking the light entering the eye first.

Disturbances of vision may already be due to changes in the cornea, for example irregularities in the surface of the cornea (astigmatism) or deviations from the norm in the horizontal and / or vertical direction.

Typical changes of the lens

When assessing the lens itself, your doctor can tell you from different patterns of turbidity, how far the cataract has progressed and which form of the star it is:

  • The bark star is classically characterized by very fine, streaky turbidity extending spokes or wedge-shaped from the bark to the center of the lens. In between, there may be columnar water retention.
  • For the core star, however, the pattern is less specific. However, the lens is especially clouded inside, while the bark remains transparent.
  • As the name implies, the posterior clouding of the shells results in a shell-like compression beneath the posterior lens capsule.

Examination of the back of the eye

In addition to the lens and the cornea, the slit lamp can also be used to examine the posterior segment of the eye. Particular attention is paid to the following areas of the eye:

  • Vitreous body (corpus vitreum)
  • Ocular fundus with retina, optic nerve, blood vessels and the spot of sharpest vision (fovea optica)

In order to assess the posterior segment of the eye, the pupils must be spread wide in preparation for medication. This can lead to an increased sensation of dazzling as well as a reduced visual acuity, which means that you will not be able to drive for a few hours after the examination.

Assessment of the posterior segment of the eye is not a regular part of an eye examination for cataracts and is only performed if there are risk factors or pre-existing conditions that could affect the vitreous or retina.

3. Further investigation methods

Further investigations, which can be made according to the shape and stage of cataract after a slit lamp examination, include:

  • Ultrasound examination of the retina
  • Measurement of visual acuity
  • Optical coherence tomography

Evaluation of the retina by means of ultrasound

In a very advanced lens opacification, it may not be possible to examine the posterior segment of the eye, and in particular the retina, using a slit lamp. In this case, your doctor will use the ultrasound scan to detect changes in the retina, such as incipient retinal detachment or retinal tumors. An assessment of the retinal condition is important, especially with regard to cataract surgery.

The retina in view: the retinometer

To measure visual acuity or determine what vision to expect following cataract surgery, the physician can perform an examination using a retinometer. Regardless of changes to the lens, the retinometer determines the resolution of the retina and provides an estimate of the expected visual acuity after cataract surgery.

The current visual acuity can be determined by means of visual charts. In cataract, especially at the beginning of a short sightedness.

OCT only in certain cases

In certain cases, optical coherence tomography (OCT) is still used. It provides information about the condition of the retina in pre-existing conditions such as age-related macular degeneration or diabetic retinopathy.

The OCT is a very special procedure that is usually performed only in certain pre-existing conditions in preparation for a cataract operation and is not a regular part of every cataract examination.

Here you can find more about:
Questions about symptoms and diagnostics


Cataract surgery is now widely used in Germany for the treatment of cataracts. During a brief outpatient stay, in short, the cloudy lens is removed and replaced with an artificial lens. The artificial lens, also intraocular lens (IOL), is mostly made of silicone or acrylic and completely replaces the function of the eye lens after the procedure.

1st operation time

You decide

If you suffer from cataracts and no other underlying diseases, then you decide when the ideal time for surgery has come. An important factor in deciding for or against surgery is not just the degree of lens opacification, but also the extent to which you are affected by the cataract in your everyday life.

As the procedure is usually performed on an outpatient basis and under local anesthesia, you should arrange for someone to take you home after the operation. Furthermore, a close ophthalmologic follow-up care must be ensured in the following period after the operation. Take care of your doctor's appointments, etc.

2. Operation procedure

The decision as to whether and when to perform a star operation is a very individual process. While a light star does not give rise to an operation, high age or pre-existing conditions in the personal history are not an exclusion criterion for an operation.

No big deal

The cataract operation is a very common procedure in Germany, which involves comparatively few risks and leads to an improvement of the visual performance in more than 90% of all cases.

If the cataract affects both eyes, it is usually operated on first, on which the star is already advanced. The second eye is then operated during the course, about four to eight weeks after the first operation.

Specifically, an operation is as follows:

First of all local anesthetic eye drops are dripped into the eye to be operated on. In some cases, the local anesthetic is injected with a very fine needle as well.

Through a small incision in the cornea, the so-called tunnel cut, access to the interior of the eye lens via the front lens capsule.The incision is about 2-3 mm small and does not need to be sutured following the operation due to the high regenerative capacity of the cornea.

Old lens out, new lens in

With an ultrasound probe introduced via the tunnel section, the core and bark of the lens are subsequently liquefied (phacoemulsification) through a specific ultrasound frequency and then aspirated via the probe. Lateral and posterior lens capsules remain intact and are left in the eye.

A small rolled-up artificial lens is then inserted over the tunnel section into the now empty capsule, unfolded there and anchored with small brackets in the middle. It now takes the place of the old eye lens and completely replaces its function.

3. After the operation

In the vast majority of cases, the operation is performed on an outpatient basis, which means you can go home immediately after the procedure.

Important: regular eye drops

The freshly operated eye is covered for the first 24 hours with an Ointment dressing, which can be removed by hand after the specified time. In the first three to four weeks after the operation, antibiotic and anti-inflammatory eye drops must be administered to the eye once or several times daily. Your doctor will tell you how to use the eye drops and what you should be aware of.

Regular visits to the doctor are commonplace after cataract surgery. At the beginning, you will have to see your ophthalmologist at very short intervals, but gradually less and less. Treatment is usually complete after four weeks.

Another view

You will feel a change in vision after removing the ointment dressing. Often, colors are seen more clearly, and the view is generally sharper. At the beginning it can also lead to an increased glare sensitivity, which is perceived as very unpleasant.

Give yourself time to adjust to the changed look. After four to six weeks, you will benefit from the operation with very high certainty.

4. Complications

Cataract surgery is the most common procedure and one of the safest surgeries ever. However, there may be complications about the frequency and severity of which you need to be aware of before surgery.

Bleeding and infections are rare

As with any surgery, bleeding or infection can occur. However, as the cornea itself is not perfused, bleeding is usually very mild. In most cases infections also occur locally and can be well intercepted or treated by medication. Only in about 0.05% of all operations are bleeding or infections so severe that there is loss of sight.

Retinal injury or retinal detachment occurs during or after about 1-3% of all operations. Retinal detachments are very painful, but can be treated well if they are detected early enough.

Renewed cloudiness

Probably the most common complication that can occur after a cataract operation is the so-called after-star. This affects approximately 30% of all operated patients and leads to opacification of the posterior capsule after surgery. It runs, like the cataract itself, creeping, so that it can come after many months to years again to a loss of vision. The after-star is relatively easy to treat by laser.

Learn more about the treatment here:
Cataract: Operation

Course and prognosis

Good prospects after the operation

If left untreated, cataracts continue for years, ending in complete blindness at worst.

By cataract surgery, however, there are very good chances to regain full visual acuity, unless you suffer from any other eye disease. In addition, existing diseases that may affect the eye, such as diabetes mellitus, it depends on the individual case. However, an improvement in vision is also achieved here by surgery as a rule.

How to protect your eyes

In many cases, the question is asked what you can do to avoid cataracts. Since the cataract is an appearance of old age, but little can be done to prevent its emergence.

However, two factors in particular have an influence on the onset and progression of lens opacity. On the one hand, it is direct UV radiation from the sun or tanning beds. Always protect your eyes with sunglasses when exposed to UV light.

On the other hand, smoking can be involved in the development of a cataract. Even with 10 to 15 cigarettes a day, the risk increases by up to 40% compared to non-smokers, to contract a cataract. So stop smoking early. Better even better: Do not even start with it.

Read also:
Questions and answers about history and prognosis

Author: Lisa Wunsch


G. K. Lang: Ophthalmology, Thieme Verlag, 2014.

G. Hahn: Short textbook Ophthalmology, Thieme Verlag, 2012.

German Ophthalmological Society (DOG): Guideline No.19 | Cataract (gray cataract) in adulthood,, last accessed on 01.02.2018.

E. Lindblad et al .: Smoking Cessation and the Risk of Cataract. A Prospective Cohort Study of Cataract Extraction Among Men. JAMA Ophthalmololy, published on Jan. 2, 2014.