CATARACTS
What is Cataract?
Inside the eye, behind the iris, there is a lens, usually transparent, called the crystalline.
The cataract consists of a loss of transparency of the lens.
Symptoms
The main symptom of cataract is a painless, progressive loss of vision. The patient experiences blurred vision, which cannot be effectively corrected with corrective lenses (glasses and / or contact lenses).
In addition, patients may have a certain intolerance to light (photophobia) and vision of halos around light sources (street lamps, car headlights, bulbs). Another symptom of cataract is the alteration in the perception of colors, which are perceived as dimmer (they have lost intensity).
Why does the cataract occur?
The main cause of cataract is aging. Most cataracts are the result of a natural aging process of the eye. After the age of 40, certain changes in the structure and composition of the lens begin to occur, although these changes may not cause symptoms until after the age of 60.
The age of onset is variable.
Various factors associated with cataract onset have been described, such as, for example, diabetes; family history of cataract; eye diseases, such as uveitis; certain treatments, such as corticosteroids (mainly inhaled); radiotherapy treatments, etc.
Some cataracts are the result of an ocular trauma (traumatic cataracts), in other cases, the cataract occurs as a complication of previous eye surgery, such as glaucoma surgery.
Sometimes the cataract appears early in life, in the form of a congenital or juvenile cataract. Many of these cases have a family history.
Can it be prevented?
Cataract, in most patients, is a process associated with the natural aging of the eye, so its prevention is not possible.
That said, there are a number of steps that can be taken to delay cataract progression as much as possible. A relationship between exposure to ultraviolet radiation and the development of certain types of cataract has been established, so using protective glasses (sunglasses) can protect and / or delay the development of cataracts. On the other hand, a diet rich in antioxidant foods has been associated with a lower incidence and progression of cataract.
Diagnosis
A routine standard ophthalmological examination, with special attention to the study of the anterior segment, may be sufficient to determine the diagnosis and the degree of the cataract. In addition to evaluating the cataract, it is essential to analyze the retina looking for other pathologies that are related to age, such as glaucoma or age-related macular degeneration (AMD).
Treatment
The only valid treatment to solve the loss of vision caused by cataract is surgery.
Cataract surgery consists of removing the lens and replacing it with an intraocular lens. The most commonly used technique is phacoemulsification of the lens. This technique is performed on an outpatient basis and under topical anesthesia, in most cases.
With the phacoemulsification technique, the lens is removed by ultrasound that undoes it, so the incisions made are much smaller than those made with older techniques, such as extracapsular. Once the lens is destroyed by ultrasound, the fragments are aspirated and removed from the eye.
Phacoemulsification has several steps:
· Access to the interior of the eye: Access to the interior of the eyeball is made through a self-sealing (closes by itself) very small incision (1.5-2.0 mm) that, in most cases, does not need stitches. Sometimes, depending on the characteristics of the patient, the entrance incision has to be somewhat larger (2.3-3.2 mm) whose closure, in most patients, does not require sutures.
· Opening of the lens capsule: The lens has several layers. The outer membrane that surrounds the lens is the capsule. After accessing the anterior chamber of the eye (anterior part of the eyeball), the surgeon opens the anterior lens capsule through a process called “capsulorresis”. Once the capsule is opened and inside that “capsular bag”, the fragmentation and aspiration of the cataract affected lens will be carried out.
· Phacoemulsification: It is performed using an ultrasonic probe equipped with a 0.9 mm diameter hollow titanium needle, which vibrates longitudinally from back to front between 30,000 and 60,000 times per second. These waves act like a chisel on the lens, dividing it into smaller fragments (phacoemulsification), which are aspirated at the same time through the ultrasound probe duct.
· Implantation (placement) of the intraocular lens: Once phacoemulsification has been carried out and after having aspirated the remains, a folding lens is inserted (either with forceps or with special injectors that do not require expanding the incision made) into the eye (intraocular lens), which unfolds inside the “capsular bag”, and the surgery is completed without the need for sutures.
A new technique has recently been developed, femtosecond laser-assisted phacoemulsification. However, the available scientific evidence has not shown that it is better than phacoemulsification.
There are different types of lens, the indication of which will depend on the individual characteristics of each case and the preferences of the surgeon.
Types of intraocular lenses:
· Monofocal intraocular lens: Until now, it has been the most commonly used type of intraocular lens. It has only one focus distance (far, near, or medium distance). In most cases the diopter power of the lens is selected to have good distance vision (optical correction, usually glasses, is used for near vision).
· Bifocal lenses: They have optical zones dedicated to far and near vision at the same time.
· Multifocal lenses: They have different focus areas, so they allow good far, near, and mid-distance vision.
· Accommodative intraocular lenses: The intraocular lens is capable of changing shape within the eye, giving it the ability to focus at different distances (focus ability).
· Toric intraocular lenses: They are used in those patients with high-base corneal astigmatism.
Prognosis/Evolution
Cataract surgery (both by phacoemulsification and using laser-assisted phacoemulsification) is very safe and has excellent visual results. However, it is not without possible risks, such as infections or retinal problems, although they are extremely rare. After surgery, it is relatively normal to feel certain discomfort (sensation of grit) of a temporary nature.
During the immediate postoperative period, you should take some precautions, such as limiting the level of effort and intensifying hygiene measures. For 2 to 3 weeks you will need to instill drops in the operated eye.
One of the most frequent complications after cataract surgery is opacification of the posterior capsule. In cataract surgery, the posterior lens capsule is preserved, in which the intraocular lens is placed. This posterior capsule, over time, can become opaque, thus producing a decrease in vision (similar to that which occurred with cataract). The solution is to perform a procedure with a laser, which creates an opening in the capsule (posterior capsulotomy), which restores lost vision.
