Phakic intraocular lenses are a real salvation for the patients with high myopia, hyperopia and astigmatism, as well as for those people for whom excimer laser vision correction is not suitable due to some individual differences of their visual systems.
Applied as an alternative method to excimer laser vision correction, the technique of clear lens extraction (a replacement with artificial lens) may, unfortunately, lead the visual apparatus to the loss of accommodation ability (the ability to maintain a clear focus on an object as its distance changes). Therefore, after this surgical interference a patient needs glasses for reading and working at a close distance. It makes sense to use this technique (clear lens extraction) when natural accommodation has been completely lost. This is usually the case with patients over 45-50 years of age.
Phakic lens implantation is successfully used in those cases when natural accommodation is still preserved and the lenses can be implanted in the eye without removing the patient’s natural crystalline lenses. Phakic lenses allow maintaining the ability of the eye to see the objects at both close and far distances.
Phakic lenses may be recommended to:
- Patients with high myopia (up to -25.0 D);
- Patients with high hyperopia (up to +20.0 D );
- Patients with high astigmatism (up to 6.0 D );
- Patients with thin cornea.
Phakic lenses implantation is in its sense similar to vision correction with contact lenses. The difference is that contact lenses are worn on the cornea whereas phakic lenses are implanted into the posterior or anterior chamber of the eye while preserving the natural crystalline lenses. In the process of implanting a positive or negative lens, the main objective is achieved - an image is focused directly onto the retina and not in front of it, as in case of myopia, or behind the retina, as in case of hyperopia.
Nowadays, ICL (STAAR, CIBA, Vision), posterior chamber models of phakic lens (implanted contact lens), are implanted most often. These models are installed directly behind the iris in front of the crystalline lenses and ensure the best optical results. If necessary, these lenses can be removed from an eye without breaking its structure and anatomy. Therefore, this interference is associated with one of few reversible procedures in refractive surgery!
In the process of implantation of phakic lenses, an ophthalmic surgeon performs all the manipulations through a 2.5 mm self-sealing micro-incision, which does not require suturing. This surgical interference takes 10-15 minutes on the outpatient basis and does not require admission to hospital. Eye drop anesthesia is used which is easily tolerated by patients of different age groups and does not exert pressure on the cardiovascular system. After the procedure a patient returns quite quickly to ordinary life. There are minimal restrictions and in most cases they involve only sanitary procedures in the beginning of the post-surgical period.
What are the advantages of posterior chamber phakic lenses?
- Being in an eye, a phakic lens does not come in contact with the iris and the cornea which prevents dystrophic changes;
- The lenses have unique properties of biocompatibility with a human eye;
- Due to their unique properties, phakic lenses protect the retina from the influence of ultraviolet light;
- These lenses secure quick recovery of the visual functions;
- Keep the cornea structure intact.
The main difficulty in using phakic lenses is high requirements to the accuracy of calculation and the choice of lenses as well as perfect qualification of an ophthalmic surgeon who is implanting the lenses. Therefore, comprehensive diagnostic testing is one of the main requirements before phakic lens implantation is performed. It is only a thorough testing, made with a whole set of modern computerized equipment, that ensures an objective and broad picture of the state of a patient’s eyesight and helps to choose a proper phakic lens and precisely calculate its parameters.
In Excimer clinics ophthalmologists choose phakic lenses for each patient keeping in mind different factors: individual state of the person’s visual system, age group, lifestyle and occupation. Excimer doctors have been certified by the companies-manufacturers of intraocular lenses. This gives them the right to implant phakic lenses and to offer the most modern services that exist in contemporary ophthalmology to their patients.