Learn about the essential diagnostic tests required before Femto LASIK. From corneal mapping to vision checks, find out how your eyes are evaluated.
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Diagnosis and Tests
The journey toward vision correction begins with a comprehensive eye examination. This is not a standard checkup but a deep dive into the health and structure of your eyes. A specialist will use a variety of high tech instruments to gather data. The goal of this phase is twofold. First, the doctor must ensure that your eyes are healthy enough for surgery. Second, they must collect the exact measurements that will be programmed into the laser system to guide your unique treatment.




Visual acuity testing is the most basic part of the diagnosis. This involves reading letters on a chart to determine how well you see at different distances. The team will measure your vision both with and without your current glasses or contacts. This helps to confirm the stability of your prescription. If your vision has changed significantly in the last year, the surgery may be postponed until your eyes have settled into a consistent pattern.
During the acuity check, the specialist measures:
Corneal topography is one of the most critical tests in the diagnostic process. This machine creates a three dimensional map of the surface of your eye. It is similar to a geographic map that shows hills and valleys. This map reveals the exact curvature of the cornea and identifies any irregularities or hidden astigmatism.
Because the laser will be reshaping this surface, having an accurate digital map is essential for achieving a smooth and precise result.
Pachymetry is the measurement of the thickness of your cornea. Since the surgery involves creating a flap and then removing a small amount of tissue underneath, your cornea must have enough thickness to remain stable after the procedure. If the cornea is naturally too thin, the surgery might not be recommended. This test uses a small probe or a specialized camera to get a reading in microns, ensuring there is plenty of tissue for a safe and effective treatment.
Critical measurements in pachymetry include:
Wavefront analysis is an advanced diagnostic tool that looks at how light travels through your entire eye. It identifies subtle imperfections called higher order aberrations. These are distortions that go beyond simple nearsightedness or farsightedness and can affect the quality of your vision, especially in low light. The data from this test allows for a customized treatment plan that addresses the unique way your eye processes light, aiming for the highest possible quality of vision.
A dry eye evaluation is necessary because the surgery can temporarily affect the nerves that signal tear production. The specialist will check the quality and quantity of your tears. If you have significant dry eye syndrome, you may need to treat it before moving forward with the surgery. Ensuring a healthy ocular surface is key to comfortable healing and clear vision in the weeks following the procedure. A stable tear film is the foundation of good sight.
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A dilated eye exam is performed to check the health of the internal structures of the eye. Drops are used to widen your pupils so the doctor can see the retina, the optic nerve, and the blood vessels at the back of the eye. This check ensures there are no hidden issues like retinal tears or thinning that could be affected by the pressure changes during surgery. It is a vital safety step to ensure the long term health of your vision.
Pupil size measurement is conducted in both bright and dim light. This is important because if you have very large pupils, you might be more prone to seeing glare or halos at night after the procedure. The specialist will compare the size of your pupils to the planned treatment area. This ensures that the laser reshapes a large enough portion of the cornea to cover your pupil even when it is fully dilated in the dark.
Conditions checked during pupil analysis:
The stability of your tear film and the health of your eyelids are also assessed. Issues like blepharitis, which is an inflammation of the eyelids, must be controlled before surgery to prevent any risk of infection. The specialist will also look for any signs of cataracts or other age related conditions. A complete picture of your eye health allows the surgical team to predict your healing process and provide you with a realistic expectation of the final outcome.
Finally, all the data collected is reviewed during a detailed consultation. This is your opportunity to discuss your lifestyle, your visual goals, and any concerns you might have. The specialist will explain why you are or are not a good candidate for the procedure based on the test results. If everything looks good, the specific parameters for the laser will be calculated. This preparation is what makes the actual surgery so fast and predictable on the day of the procedure.
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Prof. MD. Rıfat Rasier
Ophthalmology
Liv Hospital Ulus
Prof. MD. Betül Tuğcu
Ophthalmology
Liv Hospital Ulus
Prof. MD. Mehmet Murat Öncel
Ophthalmology
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Prof. MD. Osman Murat Uyar
Ophthalmology
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Prof. MD. Vedat Kaya
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Prof. MD. Ömer Faruk Yılmaz
Ophthalmology
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Prof. MD. İhsan Yılmaz
Ophthalmology
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Spec. MD. Deniz Marangoz
Ophthalmology
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Asst. Prof. MD. Erkan Bulut
Ophthalmology
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Op. MD. Müslim Beyoğlu
Ophtalmology
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Op. MD. Süleyman Mesut Karaatlı
Ophthalmology
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Prof. MD. Hakkı Zeki Büyükyıldız
Ophthalmology
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Op. MD. Emrah Dirican
Ophthalmology
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Op. MD. Ulviye Askerova
Ophthalmology
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Prof. MD. Ali Rıza Cenk Çelebi
Ophthalmology
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Op. MD. Altan Kaman
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Op. MD. Mahmut Doğan
Ophthalmology
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Prof. MD. Mutlu Acar
Ophthalmology
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Op. MD. Mehmet Fatih Karadağ
Ophthalmology
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Op. MD. Süreyya Aköz Arun
Eye Diseases
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Spec. MD. Samire Haqverdiyeva
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Spec. MD. AYGÜL TANRIVERDIYEVA
Ophthalmology
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Spec. MD. Ehmed Abdullayev
Ophthalmology
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Ophthalmology
Op. MD. Cansu Özcan Pehlivan
Ophthalmology
Contacts can temporarily change the shape of your cornea, so you must leave them out for several days or weeks to get accurate measurements.
A full preoperative evaluation usually takes between two and three hours because of the number of different machines and the dilation process.
Your vision will be blurry and you will be very sensitive to light for several hours, so it is best to have someone drive you home.
Not at all; you simply look at a light or an image while the machine takes digital pictures of your eye surface.
If your cornea is too thin for a flap, the doctor might suggest an alternative like PRK, where the treatment is done on the surface of the eye.
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