Introduction to cataracts:
The term cataract describes the clouding of the lens of the eye. Up to this day, the clouding of the lens is the most frequent cause of declining visual function. The most frequently observed form of cataract is the senile or age-related cataract. The exact pathomechanism underlying the development of this form of cataract is still incompletely understood, but surely involves disturbances in lens protein metabolism. Another component may certainly be found in the exposure of the lens to UV rays (photo-oxidative stress).
The time of cataract occurrence varies from patient to patient; in some cases, this form of cataract is already observed in the fourth life decade (presenile cataract). Further causes for the development of a cataract can be found in traumatology (blows to the eye, perforations of the eye). Also X-rays in high local doses, medications (long-term corticosteroid therapy), and metabolic disorders (e.g., diabetes mellitus) can either lead to the development of a cataract, or accelerate its development. Moreover, other ophthalmologic diseases (e.g., uveitis) may lead to lens clouding (secondary cataract). Last but not least, we should like to mention juvenile/ infantile cataracts, which can develop due to several pathogenetic mechanisms.
The following will now discuss the symptoms, diagnostics, prevention, therapy, and the visual rehabilitation of the senile cataract, the by far most frequently observed form of cataract.
One of the symptoms experienced by the patient is the decline of visual acuity. Despite optimal optical correction, the patient is not able anymore to perceive the optical symbols presented on a white background as well as with a clear lens. In traffic, this leads to the fact that in spite of optimal lighting conditions, traffic signs and sentinels are perceived only somewhat later. The decline in contrast sensitivity represents another symptom.
Compared to the original clear lens, the patient now experiences trouble to discern shapes that do not sharply/starkly contrast to the environment (shades of grey). In traffic, this means that the patient is handicapped, especially during twilight, rain and foggy conditions; with bad lighting, he sees other traffic and traffic signs only belatedly. One symptom particularly bothersome to the patient is the increased sensitivity to light.
The inhomogenous parts of the lens disperse the incoming light rays, which continue to the retina. In some cases, the patient becomes near-sighted (myopic) due to the progressive increase in ocular lens density.
As a preventive measure, the development of a cataract can be delayed by decreasing the overall load of UV rays. It is advisable to wear glasses and sunglasses with appropriate UV protection, as well as baseball caps, in exposed locations. The issue whether medications (antioxidants) may delay the development of a cataract is controversial. In either case, a clouding of the lens that has already become manifest can not be improved by conservative therapy.
The diagnosis of a cataract can be easily made by your ophthalmologist, with the help of a slit lamp (specialized microscope for eyes). In the examinations, other causes for the diminished visual functions of the patient have to be excluded. The lens consists of the capsule, cortex, and the nucleus. Within the kinds of clouding of the lens, main forms are a clouding of the cortex (cortical cataract), and/or the lens nucleus (nuclear cataract).
In case the patient has developed a cataract, the only therapeutic option is to surgically remove the clouded lens, and to implant a clear plastic lens. The indication for surgery can be made very early these days, since this procedure, by various improvements in surgical technique and equipment in recent years, has become a low-impact and very safe surgery, with an extremely low rate of complications. These days, there is no waiting around anymore for the lens to get “mature”, but the decision is made based on the optical problems and the lifestyle of the patient.
However, before surgery, the expected optical correction after surgery should be discussed in detail. The eye is measured before surgery, and the refraction of the artificial lens required for the patient is calculated. Possibilities include to choose a refraction that only requires reading glasses and enables the patient not to need corrective lenses for the distance, or to be without reading glasses, and to wear distance glasses. There are also artificial lenses that enable the patient to live entirely without glasses (multifocal lenses). Artificial lenses that are able of accommodation are also in the pipeline; however, as of today, sufficiently efficient systems have not been developed yet. For this decision, the situation of the second eye is immensely relevant, and a detailed consultation with your ophthalmologist is imperative. Choosing the best artificial lens for the individual patient is of immense importance, considering the multitude of different lens materials and types of lenses.
Utilizing the small incision technique, the lens can be removed after an incision of less than 3mm, after which a folded-up artificial lens can be implanted. In this, first the anterior lens capsule is opened with a curvilinear incision, the lens nucleus is vaporized by ultrasound and removed by suction (phacoemulsification), the cortex is suctioned off, and a folded artificial lens is implanted through the small incision into the clear lens capsule. The capsular bag serves as a supporting retainer for the lens. Since the incision acts like a valve, sutures are entirely unnecessary.
The procedure is nearly always performed in local anesthesia (by injection or eye drops), since this technique is less stressful to the patient. Thanks to the eye drop or intracapsular anesthesia, the patient does not have to discontinue anticoagulant medications (e.g. Aspirin, clopidogrel, Thrombo ASS, Marcumar, etc.). If the second eye has developed a cataract as well, this can be operated on as well, after some time has passed.
If there are no complications, the patient can resume his usual life within hardly any time at all; however, he should discuss general behavior modifications with his surgeon. Other than rubbing the eye, there basically aren’t any restrictions anymore. An anti-inflammatory eye drop therapy should be applied for an appropriate amount of time (a few weeks). The answer to the question as to when the patient can operate a vehicle again depends on the visual function of both eyes.
As a basic principle, the patient should discuss his fitness to drive with his ophthalmologist.
Cataract YAG laser:
In some cases, the capsular bag may become cloudy years later (after- cataract). This change results in a decrease of visual function. A small hole in the opacified capsular bag, made using laser technology (neodymium:YAG laser), however, helps quickly and is completely painless. This procedure can be applied on an outpatient basis as well, after this, the patient is not subject to any restrictions, only an eye drop therapy has to be applied for a few days.