Preliminary examination
Prerequisite for successful laser surgery is a thorough preliminary examination at our clinic at a prearranged time. Several different examination methods are necessary to obtain a comprehensive picture of your eye. You should plan approximately 2 hours for this. The examinations all take place on one day and are painless.
Eye drops will be administered for the examination of the back part of the eyes. The drops dilate the pupils, which could temporarily impair your vision. Therefore, you must not drive after the examination. We recommend that you arrange for someone to drive you home. In addition, you should not wear contact lenses for 2 weeks before the examination as they may cause an irregular corneal surface, which would result in incorrect measurements.
The preliminary examinations necessary for successful treatment are divided into five parts. Once they have been completed the patient will know whether surgery is an option and which method would be most suitable.
Diagnostics Part-1
Corneal topography: With this method, the structure of the cornea is analysed and displayed graphically. It examines the shape of the curvature, the refractive power, the thickness of the cornea as well as the surface and the condition of the front and back of the cornea. These data allow the doctor to create an individual profile and to detect any irregularities (e.g. astigmatism).
Pupillometry: Pupillometry measures the size of the pupil in light, darkness and twilight conditions. This examination is particularly important as LASIK surgery can only be performed up to a certain pupil diameter.
Diagnostics Part-2
Aberrometry: Aberrometry (wave front measurement) is a new procedure for determining the different refraction defects of the eye. It measures light rays reflected by the eye. The shape of the rays tells the doctor of any irregularity in the cornea. If there is any irregularity, the light rays are unevenly refracted. These deviations of the wave front are known as aberrations. A computer is used to save and analyze the data. The laser can be programmed and the cornea individually modeled based on that information (Wave front LASIK).
Diagnostics Part-3
Binocular status: Here, the doctor examines the patient’s vision with two eyes along with his/her spatial vision, tests the flexibility of the eyes and evaluates their position. This examination also allows diagnosis of hidden squinting.
Perimetry: Measurement of the field of vision includes the entire field of vision from the centre to the outer edge. This procedure determines the functionality of the optic nerve and the visual cortex.
Seeing contrast: This part of the preliminary examination tests the patient’s recognition of optotypes of different brightness and size by means of lamps that simulate different lighting situations.
Diagnostics Part-4
Schirmer test: The Schirmer test examines tear production. This function must be checked in advance because tear production may be reduced after LASIK surgery. If too few tears are produced even before surgery, this has to be taken into account when planning post-operative treatment. In this test, a strip of litmus paper is placed in the edge of the lower eyelid of each eye. Then the eyes are closed. After 5 minutes, at least 1.5 cm of the paper strip should be moist.
IOL Master: This examination measures the length of the eye and the refractive power of the cornea in order to calculate the correct lens implant for any later surgery for cataracts.
Diagnostics Part-5
Ocular fundus in mydriasis: Mydriasis is the dilation of the pupil. The doctor can bring about this situation by administering mydriatic drops to the eye. Dilated pupils allow examination of the ocular fundus. This may be necessary to detect congenital or acquired changes.
Intra-ocular pressure: Measurement of the intra-ocular pressure is important to detect pathological changes in the eye (e.g. glaucoma). Therefore, measuring the intra-ocular pressure is an essential component of the preliminary examination.
