For planning a surgical procedure on the eye, such as
precise eye measurement is necessary. This is the only way the doctor can recommend the right treatment method and plan an operation precisely.

Cross-section of the eye with cornea, iris, crystalline lens, vitreous body and retina (from left to right) © reineg | AdobeStock
Biometry of the eye provides an accurate picture of the eyeball and its anatomical measurements, such as
- the refractive power of the eye
- the length of the eyeball from the cornea to the retina (axial length)
- the distance between the cornea and the crystalline lens (anterior chamber depth)
- the thickness of the cornea
- Keratomy of the eye (corneal curvature radius)
This is not only used to determine possible treatment methods. Treatment success can often be predicted in advance. The aim of a surgical procedure is usually
- to halt the progression of an eye disease,
- the prevention of serious damage to vision or
- or, in the best case, to improve vision.
By measuring the eye, the ophthalmologist has the necessary data to treat the patient optimally. The data is used, for example, to produce a precisely matched artificial eye lens.
Eye measurement using ultrasound
Eye measurement using ultrasound has proven itself over many years. As the ultrasound device is placed on the eyeball, it must first be anaesthetized using special eye drops.
Optical biometry achieves more precise results (see below). Ultrasound eye measurement has one advantage over optical biometry: it is also possible if there is a massive opacity of the cornea or lens that prevents a view of the inside of the eye.
An ultrasound examination of the eyes is covered by statutory health insurance.
Optical biometry
Eye measurement using a weak, harmless laser is known as optical biometry. The laser achieves the most precise measurement results and is therefore more accurate than an ultrasound eye measurement. However, the costs of this procedure are not usually covered by statutory health insurance. Patients must pay for the examination out of their own pocket.
The procedure is non-contact, which means that no measuring instruments come into contact with the eye. This means that there is no pain associated with the measurement.
Optical biometry enables the exact measurement
- the corneal thickness
- the corneal radii and
- the axial length (and also partial lengths, such as the depth of the anterior chamber and the thickness of the lens).
The measurement results of optical biometry using lasers are superior to those of ultrasound measurement. This benefits patients in particular when correcting visual impairments due to lens opacification. Interventions to improve their visual performance then show better results due to the more accurate results.
Biometry of the eye using Pentacam
This procedure is also not covered by statutory health insurance.
The Pentacam is an automatically rotating camera. It measures the anterior segment of the eye in a matter of seconds and without contact.
The anterior segment of the eye includes the
- the cornea
- the anterior chamber of the eye and
- the lens of the eye.
The Pentacam creates a three-dimensional image of the anterior segment of the eye, which can be digitally rotated as required. This enables early detection of changes to
- the cornea,
- the iris or
- the lens
can be detected at an early stage.
In contrast to optical biometry, the Pentacam does not measure the entire eye, but only the anterior region. However, eye measurement via Pentacam is very well suited to detecting
Wavefront measurement
Wavefront measurement is a recent procedure that determines the eye's aberrations and creates a visual profile.
With the help of this visual profile, extremely precise corrections to visual performance can be made using
- laser treatments or
- the production of individual visual aids (glasses or contact lenses)
are possible.
With optical biometry, the patient does not have to take any special measures after the examination. As the examination is non-contact, visual performance is not affected at any time.
Before the examination, the patient should not wear soft contact lenses for one week and hard contact lenses for three weeks.
Before an ultrasound eye biometry, the surface of the eye must be locally anesthetized using eye drops. It then needs a certain amount of time to wear off. Only then can the patient go home safely.
In addition, there is always a risk of damaging the corneal surface(corneal erosion) due to contact with the cornea. This is very painful, but usually heals within a few days without any consequences.
There are also occasional mild side effects: patients complain of
- a foreign body sensation in the eye,
- irritated eyes and
- a strong flow of tears.
Depending on the severity of these symptoms, it may be necessary to treat them with eye ointments or eye drops. Increased sensitivity of the eye to light is less common.
However, all symptoms will subside within hours or days at the latest. You should also rest your eyes the day after the eye measurement. This includes not watching too much television, spending too much time at the PC or reading too much.
You should always protect your eyes from excessive sunlight anyway. This allows the eyes to recover quickly from any strain caused by the measurement.
If possible, schedule your eye measurement appointment for after work or on a day off. It can also be helpful to have a companion who can look after you on the way home.