There are many cases, in which cataract (partial or full opacity of the crystalline lens) is complicated by astigmatism (the Latin word meaning absence of focal point. This ailment develops due to the incorrect non-spherical shape of the cornea (corneal astigmatism) or, more rarely, of the crystalline lens (lenticular astigmatism). The corneal astigmatism has greater impact on vision than the lenticular astigmatism since the cornea possesses greater refractive capacity. Medical statistics show that astigmatism of the cornea is also more common.
A so-called "physiological" astigmatism is present practically in every person. If astigmatism is less than 0.5 D it does not require correction since it has no serious effect on the quality of vision. Cases of a higher astigmatism require correction. At a young age, astigmatism may be partially or fully compensated through the potentials of the organ of vision and sometimes the person does not even suspect the presence of astigmatism.
With age, the compensatory potentials of the body are reduced and astigmatism starts to affect vision, dramatically distorting it. Therefore, the presence of astigmatism in old-aged patients complicates the process of selecting glasses and ensuring quality vision. In practical terms, astigmatism of over 2.0 D makes it difficult to select proper glasses.
In the past, cataract combined with astigmatism posed certain difficulties for the surgeon since even after extraction of the cataract the patient had poor sight and required special cylindrical glasses. The development and active introduction into practice of AcrySof Toric lenses allowed patients with cataract and astigmatism to enjoy a new quality of vision.
Image under cataract
After cataract extraction and
standard IOL implantation
After cataract extraction and
toric IOL implantation
The toric lens has great refractive power in certain spots which allows the lens to reduce and often eliminate cornea astigmatism, thus considerably improving uncorrected distance vision.
Toric lenses may be recommended:
- To patients with cataract;
- To patients with astigmatism from 0.75 to 3.0 D;
- To patients with acquired astigmatism;
- To patients with a corneal problem;
- To patients with corneal traumas and unsuccessful refraction surgery;
- To patients with corneal transplantation (in most cases such patients display high astigmatism which results in serious problems when prescribing glasses or contact lenses).
Toric intraocular lens — is implanted to replace the cataract crystalline lens by means of an effective, reliable, and safe surgery based on phacoemulsification.
In the course of toric lens implantation, the ophthalmic surgeon performs all manipulations through a self-sealing micro-incision of up to 2.5 mm which does not require suturing. This kind of surgery takes from 10 to 15 minutes on an out-patient basis and does not require admissions. The surgery is performed with drop anaesthesia which is easily tolerated by patients of all ages and does not affect their cardio-vascular system. After this procedure, the patient quickly returns to normal life. The limitations are minimal and mainly mean hygienic procedures immediately after the surgery.
The toric lens not only substitutes the optical force of the ablated blurred crystalline lens, but also corrects the initial corneal astigmatism.
The main difficulty in the application of toric lens is aasociated with high requirements for the precision of both calculation and selection of lenses, as well as with perfect performance of the ophthalmic surgeon in the course of implantation of the lens. The lens has to be placed in the eye with great accuracy since this affects the correction of astigmatism in the required axis. Hence, comprehensive diagnostic testing is one of the major prerequisites for toric IOL implantation surgery. Only comprehensive diagnostics conducted with help of a complex of up-to-date computerized equipment ensures a complete and objective picture of the patient’s vision state and allows for correct selection and calculation of the parameters for the toric lens.
In the process of selection of toric lenses, the ophthalmologists of the Excimer Eye Clinic take into account various specific features of the eye, the age of the patient, the way of life, and occupation. Each toric lens is ordered on an individual basis. This means the patients have to wait for the surgery for some period of time. The medical personnel of the Excimer Eye Clinic have been certified by the manufacturers of the intraocular lenses to implant toric lenses and offer their patients the latest achievements in ophthalmology.