CATARACTS

CATARACTS

What is a cataract?

Cataracts are a clouding of the crystalline lens causing a decrease in vision. The crystalline lens is a natural lens in the eye, it is transparent and allows you to see. When clouding of the lens occurs, vision will be more blurred. Cataracts generally begin to make an appearance from 65 years of age on average (senile cataracts). It can also occur at a younger age due to metabolic diseases such as diabetes. Also the cataract can be due to the prolonged taking of drugs such as corticoids or following an eye trauma.

Symptoms

The symptoms experienced are a gradual decrease in vision, especially from afar. We can therefore have visual fog, double vision, annoying glare in the light and a decrease in colour vision. Furthermore, cataracts are not a disease but a natural ageing of the lens.

Treatment

The treatment for cataracts is surgery. The decision to operate a cataract is generally made based on the level of the patient’s visual impairment as it is an elective surgery with the aim of improving sight. Whether the operation is advisable or not therefore depends on the discomfort felt by the patient due to his cataract.

OPERATION OF THE CATARACT BY PHACOEMULSIFICATION

Aim of the cataract operation

Cataract surgery is undergoing constant technological innovations. The goal of cataract surgery is to remove the crystalline lens and replace it with an artificial lens (intraocular implant).
The objective will be twofold. First, by removing the cloudy lens, you improve vision (by restoring transparency of vision). Second, we can choose the artificial lens to implant in the patient’s eye so as to correct his pre-existing visual anomalies (myopia, astigmatism, hypermetropia, presbyopia). Thus, the patient can see clearly and without glasses from afar as well as up close.

We have entered the era of refractive cataract surgery. Indeed, the implant placed in the patient’s eye will be fully personalised to correct the patient’s refractive anomalies (Premium implant).

Operation procedure

Cataract surgery is an outpatient surgery so the patient goes home immediately after the procedure. The operation lasts about 10 to 15 minutes and is done under local anaesthesia after instillation of anaesthetic drops on the eye. In addition, the patient receives an intravenous injection of a relaxing product. During the operation, the patient sees nothing because he is blinded by the light of the microscope. Thanks to this anaesthesia, the patient avoids general anaesthesia (always more risky, especially in elderly patients) and does not feel pain. The patient thus retains the sensations of touch, but without pain.

The operation takes place in several stages. First, the surgeon will make an incision of less than 2 mm in order to extract the crystalline lens. The latter is then fragmented and aspirated by ultrasound (“phakoemulsification” technique). Then, once the lens has been removed, the surgeon implants a custom lens in the patient’s eye to allow him to see as fully as possible without glasses.

A preliminary implant calculation will be necessary before the operation based on the measurements of the patient’s eye. Thus, the surgeon will be able to choose the type and strength of the implant suited to the patient.

INTRAOCULAR IMPLANTS

Cataract surgery has seen real progress in the manufacture of new intraocular implants. Indeed, the objective is to give the patient a better quality of vision and maximum independence from glasses. These implants correct pre-existing visual impairments such as astigmatism and presbyopia. In addition, they are made to measure in that they are completely personalised to the patient’s eye, and are called “premium” implants.
Furthermore, the implants are lenses made of acrylic. They are injected into the eye through the small 2 mm incision and unfold in the eye. These implants remain in the eye for life and do not need to be changed.

1 – Monofocal implants:

By choosing the right implant strength according to the patient’s implant calculation, we can correct pre-existing myopia or hypermetropia. These traditional implants only correct myopia or hypermetropia and give an excellent quality of vision.

At the end of the operation, the patient will wear a patch overnight for a week. In addition, post-operative care will consist of the instillation of antibiotic and anti-inflammatory drops in the eye for one month.

2 – Multifocal implants:

These are implants whose design and geometry allow the light to be diffracted into two focal points so that the patient can see from far and near without glasses. However, implants correcting presbyopia are only suitable if the patient is not astigmatic because multifocal implants do not correct astigmatism.
Thanks to these implants, the patient will be able to see from afar and up close without glasses. It should be noted however that good light will be needed for reading close up. A pair of extra glasses will also be necessary in certain circumstances (extended reading and computer use, driving at night).

The drawback

Multifocal implants make increase the appearance of light halos (light circles seen around the lights) in the dark. Indeed, they cause a greater alteration in quality of vision compared to monofocal implants. Multifocal implants allow everybody to see from afar. On the other hand, they offer, depending on each model, a certain reading distance up close without glasses. Indeed, some models allow you to read well up close without glasses at 33 cm but blur in intermediate vision (at 50 cm). While other models offer the opposite. It will therefore be necessary for the patient to put himself at the right distance to see clearly up close and to focus. The depth of field is generally not high.

Choice of implant

The choice of implant model will depend on the patient’s priorities (near vision or intermediate vision). New so-called “trifocal” implants have been designed to increase this depth of field. Thus, the patient can see from a distance, an intermediate distance and close up without glasses.

Multifocal implants remain a compromise between being as independent as possible from glasses for both far and near sight at the expense of the quality of vision. Patients who are very demanding of the quality of vision are not good candidates for these implants and should opt for conventional monofocal implants or pseudo-accommodative implants.

3 – Toric implants:

Toric implants correct and reduce the astigmatism generated by the cornea.
Conventionally, implants did not correct astigmatism and you had to wear glasses for far and near sight after the operation to correct the astigmatism.

In recent years, toric implants have been created to correct astigmatism.
These implants are more powerful on a single part of the lens which must therefore be placed on the most bulging axis of the cornea. Thus, it corrects in the eye the astigmatism generated by the most bulging axis of the cornea.

These implants are more difficult to place in the patient’s eye because they will have to be turned carefully to place them on the right axis. Markers will thus be traced on the patient’s eye with a felt-tip pen before operating to locate the correct positioning.

These implants will therefore correct myopia or hypermetropia in the patient and also the astigmatism of his / her cornea. This implant must first be calculated on a website, based on all of the patient’s data, and will be custom-made. Thanks to toric implants, a patient will be able to see from afar without glasses.

Risks of the surgery

Cataract surgery, like any surgical procedure, is not without risks, even if they are very rare. The main risk is infection of the eye, the incidence of which is exceptional, but whose visual prognosis is not good. Intraocular infections (called endophthalmitis) are due to germs contracted in the majority of cases after the intervention. The intraocular injection of antibiotics at the end of the procedure makes it possible to further reduce the frequency of this complication. The patient must be informed of this possibility because in the event of a red and painful eye after the operation, s/he must urgently consult with their doctor to check for infection which, if present, would be a therapeutic emergency. Eye infection usually occurs within a week of the operation and manifests as redness and pain in the eye.

Other possible complications are inflammation of the retina, corneal oedema and retinal detachment. The latter, observed especially in patients who were previously myopic, requires emergency surgery.

The most common but least serious complication is a secondary cataract, which corresponds to the appearance of opacity behind the implant a few months after the operation, which causes vision to decrease once more. Treatment consists in making a hole by laser behind the implant to regain the transparency of vision. The secondary cataract will not return afterwards.

Other symptoms such as dry eyes manifested by burning eyes, tingling, and tearing may also appear after surgery and will be treated with artificial tears.