The most common type of surgery is phacoemulsification. In this procedure, the nucleus of the crystalline lens is fractured and aspired into its own capsular bag (the pocket of tissue where the crystalline lens is located), with the help of an ultrasound probe that is inserted into the eye through a 3 mm incision.
The anatomy of the crystalline lens allows for the ultrasonic fragmentation. The lens is described as having three different areas; the cortex which is the most superficial, the epinucleus and the nucleus. The dissection of the nucleus begins after the capsulotomy (incision of the capsule is sculpted and fragmented). The fragments are extracted later through aspiration.
In the next step, the foldable intraocular lens in placed in the eye, replacing the crystalline lens. The lens must be perfectly placed within the capsular bag.
In the majority of cases sutures are not required.
This procedure is carried out with only the use of a topical anesthetic (eye drops), without the need for an injection. The patient leaves the operating room with both eyes open.
The traditional surgical procedure for treating cataract is known as extracapsular. The greatest inconvenience of this technique is the large incision it requires for the extraction of the integrated cataract from the interior of the eye. Three to four sutures are needed which can cause corneal astigmatism and a much longer recovery period.
The technology of the intraocular lenses (IOL) and the surgical techniques are constantly evolving. There are many types of IOL that differ depending on the type of material used, the geometric characteristics and the surface properties.
The rules relating to the manufacture of these lenses and the quality control measures are very strict.
These lenses must meet certain optical requirements: they must have excellent resolution; a spectral transmission equivalent to that of a normal crystalline lens; the absence of any abnormalities; minimal internal reflection; in the case of offsetting or inclination they should cause minimal changes in power and be free of any surface
aberrations; and they should have an appropriate diameter in relation to the size of the patient’s pupil.
The materials used in the fabrication of the IOLs, whether they are rigid or flexible, should have an optimal intraocular biocompatibility and must be physically, optically and chemically stable so as to not cause an inflammatory physiological reaction and/or fibrosis.
Rigid intraocular lenses made of PMMA (acrylic) have been, until today, the most commonly used, providing excellent results. New materials used in flexible IOLs (silicon, acrylic, hydro gel and thermo-plastics), now allow for the implantation of these lenses with minimal risk or postoperative trauma.
The choice of lens is determined by the clinical characteristics of the patient’s eye and the preferences of the surgeon.
Who can undergo cataract surgery?
Cataract surgery can be performed on anybody, regardless of any associated illness, as it does not require the administering of a sedative or toxic drug.
The disorder caused by the evolution of a cataract is experienced differently in each patient. The age, profession, visual needs and living conditions of each patient should be taken into account when deciding the appropriate time for undergoing the surgery.