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Vision Disorders – and Their Correction

Refractive error

The eye lets you “see” by performing two functions: receiving light, and focusing it on the retina, which converts the light into electrical impulses and transmits them on to the brain. Both the cornea and the lens are involved in focusing that light on the retina. If the light does not hit the retina in focus, the a “refractive error” – or “ametropia” occurs. In Europe, almost 25% of the population show a refractive error.

Normal Vision

When cornea and lens bend the rays of light in a way so that it is focused on the retina, then the eye is without optical error. A person with normal vision is able to see objects clearly both at near and at far. This vision is termed “emmetropia”.

Short-sightedness

If the light rays that enter the eye are focused in a point in front of the retina, then the eye is “myopic” and the person is described as being “short-sighted”. Objects in the distance are blurred, and only light coming from nearby objects is projected onto the retina sharply. Myopia typically occurs because the eye is too long for its optics, but it may also be due to a steeply curved cornea.

Short-sightedness

If the light rays that enter the eye are focused in a point in front of the retina, then the eye is “myopic” and the person is described as being “short-sighted”. Objects in the distance are blurred, and only light coming from nearby objects is projected onto the retina sharply. Myopia typically occurs because the eye is too long for its optics, but it may also be due to a steeply curved cornea.

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Farsightedness

The opposite of myopia is called hyperopia (farsightedness). Rather than being focused on the retina, rays of light are instead focused on a point behind it. In this case, the eye is too short for its optical system (or the curvature of the cornea is too flat). However, many people can correct for their farsightedness through lens accommodation – they can consciously change the shape of their lens to focus light sharply on the retina to view near objects. While this works fairly well at young age, it will lead to eye strain and headaches by the age of 45: the ability of the lens to accommodate diminishes, and the ability to see nearby objects in focus is lost.

Astigmatism

To see in focus, the image of the outside world needs to be projected onto the retina. But in people with normal astigmatism, the cornea has a shape that nakes it looke like an egg, rather than a ball. The focal point is scattered; this means that the image isn’t completely in focus on the retina; some parts are in focus, other parts aren’t.

Presbyopia

If you’ve ever used a traditional SLR camera, you know that you can manually focus the lens by twisting it, which changes the distance of the lens to the photographic film or digital sensor. It’s the same with your eye’s lens. The lens is held in a transparent bag that is suspended from ciliary muscles – which can contract and relax to change the shape of the lens, achieving focus.

If the SLR camera’s focusing mechanism starts to rust, it gets harder and harder to move it and focus; eventually it will stop moving and it gets fixed to one focal length: only objects at one distance will be in focus; everything else is blurred. It’s similar with the eye; as you age, the lens gets stiffer and stiffer; the ability of the ciliary muscles to change its shape gets lower and lower, until (like the rusted SLR camera lens focusing mechanism) the lens is rigid, fixed to a single distance and everything else is blurred.

Correction of visual errors

The classic method of vision correction has been to use spectacles. But there are a number of other methods that can be used to correct visual defects.

Contact lenses

They offer an excellent way of correcting refractive errors, and are usually well tolerated to begin with. However, over time, many people become intolerant of contact lenses. Wearing them becomes uncomfortable and the risk of infection increases.

PRK

Photorefractive keratectomy (PRK) involves the use of an excimer laser to reshape the cornea to correct refractive errors like myopia, hyperopia and astigmatism. 

TransPRK

This is a completely non-contact method of performing PRK, in which the excimer laser is used to remove the corneal epithelium before reshaping the corneal stroma. The laser platform we use offers “SmartSurface” PRK which generates a smooth cornea which has optical advantages over previous generation lasers.

LASIK

Laser in situ keratomileusis. The cornea is cut to generate a flap, which is folded back and an excimer laser reshapes the underlying cornea. The modern variant is femto-LASIK, in which the incision required to make the flap for the procedure made by a second laser (a femtosecond laser) instead of a mechanical blade called a microkeratome. 

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Augeninstitut ELZA
4.8
Based on 109 reviews
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mike
mike
09:02 04 Jan 23
Overall as a 50 year old, who wanted to continue to avoid wearing glasses and/or contact lenses, my goal was 100%... achieved with ELZA and Dr. Hafezi. I greatly appreciated the overall approach by Dr. Hafezi and his friendly and competent team in reviewing my vision at the start and following a comprehensive eye exam- the explanations of my options. For me I chose PRK in one eye for a monovision solution to correct short sightedness which was becoming more prevalent in night driving and sports such as skiing and cycling. PRK heals slowly but the outcome is worth the wait- and the cost- you use your eyes every waking moment- and for me I cannot see any reason not to pursue better vision with the ELZA team! A great quality of life enhancement!read more
Zuzana Fecko
Zuzana Fecko
21:48 31 Oct 22
Thank you so much, Dr. Torres and prof. Hafezi. 26 years I was only “dreaming” about the eye surgery due to possible... complications. I was worried ..Thank you for encouraging me to make a decision and thank you for your professionalism, explanations and great work!I wish you all the best, lots of success and only happy patients!read more
Serena Fazio
Serena Fazio
11:15 06 Mar 22
I have been to the ELZA clinic to have surgery for my miopy, as my eyes were rejecting the contacts and I was tired of... wearing glasses. From the first preliminary visit, to the actual surgery and post-surgery care Dr. Hafezi and all his collaborators have been extremely professional, considerate and helpful. All the steps of the (very short!) surgery were thoroughly explained to me in order to be as calm as possible, together with the medication plan and precautions to be aware of so that my eyes could heal in the best way possible. By following their exact instructions, the healing process has been very successful and smooth, and after about one week I was able to see perfectly. I absolutely recommend this team and their expertise!read more
Robin A
Robin A
11:43 16 Feb 22
Top experts and professional team. Highly recommended
Thunder Shiviah
Thunder Shiviah
14:05 23 Nov 21
After some research on local options I decided to go with ELZA since it stood out as the best. The operation and the... post-operation recovery went extremely smooth (something I was worried about with PRK). Now my vision is much better than I had hoped and I have no side effects such as dry eye or night vision problems. Thank you!read more
Thomas S.
Thomas S.
09:37 07 Jul 21
My left eye had to be operated on because of a cataract. As I had an Artiflex lens implanted a few years ago, it had to... be removed first before a modern lens could be implanted to correct the cataract. Prof. Hafezi treated me in an very competent and friendly manner. I am very happy with the result.read more
Selma A. Rahim
Selma A. Rahim
19:45 02 Jul 21
Dr. Hafezi.. the KING OF CXL🤴
Gianluca Ricci
Gianluca Ricci
12:46 10 Apr 21
Great team and service!
rehaneyecare
rehaneyecare
05:36 08 Apr 21
Excellent surgeon
Steven H.A
Steven H.A
16:13 11 Jan 21
Prof. F. Hafezi s expertise is enormous and he has a very pleasant and calm nature which gives the patient... security.Thank youread more
Online Commande
Online Commande
09:19 05 Dec 20
Totally creepy, very arrogant Prof.He just want your money.It may explain, why this Prof. is not in the center of the... city of Zürich and why he has been thrown away from University of Geneva.read more
Elena Churilova
Elena Churilova
10:06 17 Nov 20
At the moment, 3 months have passed since the moment I made laser vision correction in this clinic. and I can say that... I am happy that I chose this particular clinic and Prof. F. Hafezi. The entire staff of the clinic is very friendly, treats patients with sympathy and patience if they are nervous before surgery (my big gratitude to Aida Alili for all support and patience). The doctor Hafezi and other doctors of the clinic are very professional and ready to explain to you as many times as you need. I can only recommend!read more
Michele Aggiato
Michele Aggiato
18:17 10 Jan 20
The day I had Prof Hafezi checking my keratoconus I knew I was finally in the right place after years of searching for... a good ophthalmologist. Prof Hafezi recommended a surgery due to a drastic degeneration of my cornea. The surgery was performed by himself with the assistance of Dr Rodriguez, one more collaborator of Prof Hafezi’s team who got my full trust.read more
Ashley Faulkes
Ashley Faulkes
15:30 21 Mar 16
Professor Hafezi and the team at the ELZA Institute have done an amazing job of creating a first class eye clinic, with... cutting edge technology and support. I went there for a dry eye issue and other issues with my prescription, and they were easily able to help me and put me on the road to better vision! High recommend them to anyone in the Zurich/Aargau area.read more
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Augeninstitut ELZA
4.8
Based on 109 reviews
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