Cataract

Introduction and Facts

Cataracts are the leading cause of preventable blindness worldwide. A cataract is an eye disease characterized by clouding the eye lens, thus interfering with the process of light entering the eye. A disturbance can cause cataracts in the control mechanism of water and electrolyte balance due to denaturation of lens proteins or a combination of both. About 90% of cataract cases are age-related; Other causes are congenital and trauma. According to the 2013 Riskesdas survey, the prevalence of cataracts in Indonesia is 1.4%, with respondents without age restrictions.

Pathophysiology

The standard lens is the iris's posterior structure, which is clear, transparent, shaped like a shirt button, and has high refractive power. The lens contains three anatomical components. In the central zone is the nucleus, in the periphery is the cortex, and surrounding both the anterior and posterior capsules. With age, the nucleus changes color to yellowish-brown. Around the opacity, there is a spine-like density anterior and posterior to the nucleus. The opacity of the posterior capsule is the most significant form of cataract, appearing as snow crystals on the window.

Physical and chemical changes in the lens result in a loss of transparency. Changes in the multiple fine fibers (zunula) that extend from the ciliary body to the area outside the lens, for example, can cause vision to be distorted. Chemical changes in lens proteins can cause coagulation, thereby blurring vision by blocking the passage of light to the retina. One theory is that the disruption of normal lens proteins occurs with an influx of water into the lens. This process breaks the strained lens fibers and interferes with light transmission. Another theory says that an enzyme has a role in protecting the lens from degeneration. Enzyme levels decrease with age and are absent in most patients with cataracts.

Cataracts usually occur bilaterally (both eyes), but have different rates. It can be caused by traumatic or systemic events, such as diabetes. However, most are a consequence of the normal aging process. Most cataracts develop chronically by the time a person enters the seventh decade. Cataracts can be congenital and must be identified early because if not diagnosed can lead to amblyopia and permanent vision loss. Factors that most often play a role in the occurrence of cataracts include ultraviolet B radiation, drugs, alcohol, smoking, diabetes, and inadequate intake of antioxidant vitamins in the long term.

Symptoms and Complications

Cataracts are diagnosed primarily by subjective symptoms. Usually, patients report a decrease in visual acuity, glare, and some degree of functional impairment due to vision loss; the objective findings usually include pearl-gray condensation in the pupil so that the retina will not be visible with the ophthalmoscope. When the lens becomes opaque, the light will be scattered instead of being transmitted sharply into a focused image on the retina. The result is blurry or dim, distracting blinding with shadow distortion and difficulty seeing at night. The pupil, which is usually black, will appear yellowish, gray, or white. Cataracts typically develop gradually over the years, and once the cataract has worsened, even stronger correcting lenses will not improve vision.

If cataracts are left untreated, complications such as glaucoma and uveitis will occur. Glaucoma is an abnormal increase in intraocular pressure that causes optic nerve atrophy and blindness if not resolved (Doenges, 2000). Uveitis is inflammation of one of the structures of the uveal tract (Smeltzer, 2002).

Diagnosis

The diagnosis of cataracts in patients is based on anamnesis and physical examination. The main complaint is blurred vision (such as seeing smoke) accompanied by glare when looking at light. On physical inspection of the eye, it was found that the eye lens was cloudy, the pupillary reflex could be positive or negative, and the shadow test was positive. In addition, an ophthalmoscope can be performed.

Management & Maintenance

Surgery is performed when visual acuity has decreased to such an extent that it interferes with daily work or when it has caused complications such as glaucoma and uveitis (Mansjoer, 2000). The lens is removed from the eye (lens extraction) in cataract surgery by an intracapsular or extracapsular procedure. Intracapsular extraction, which is rarely done nowadays, is to remove the lens in toto, i.e., inside the capsule through a superior limbus incision 140-1600. In extracapsular extraction, a superior limbus incision is also performed. The anterior part of the capsule is cut and removed, the nucleus is extracted, and the lens cortex is removed from the eye with irrigation and aspiration or no aspiration, leaving the posterior capsule. Phacofragmentation and phacoemulsification by irrigation or aspiration (or both) are extracapsular techniques that use ultrasonic vibrations to lift the nucleus and cortex through a small (2-5 mm) lumbar incision, thereby facilitating postoperative wound healing. This technique is less proper in dense senile cataracts, and the advantage of a small lumbar incision is somewhat diminished when an intraocular lens is inserted.

In the past few years, extracapsular cataract surgery has replaced intracapsular procedures as the most common type of cataract surgery. The main reason is that if the posterior capsule is intact, the surgeon can insert an intraocular lens into the posterior camera. The incidence of postoperative complications such as retinal detachment and macular edema is less when the posterior capsule is intact. If a slight incision technique is used, the postoperative healing period is usually shorter. The patient can be outpatient on the same day of surgery but is advised to move cautiously and avoid stretching or lifting heavy objects for about a month. The eye can be bandaged for several days, but if the eye is comfortable, the dressing can be removed on the first postoperative day and the eye protected with glasses. Night protection with metal shields is required for several weeks. Temporary glasses can be worn a few days after surgery, but patients usually see pretty well through the intraocular lenses while waiting for permanent glasses. (Vaughan, 2000)

Reference:

1. Astari P. Cataracts: Classification, management, and complications of surgery. Mirror of the World of Medicine 2018;45(10):748-53

2. Cataract [Internet]. [cited 2021 Aug 26]. Available from: http://digilib.unimus.ac.id/files//disk1/127/jtptunimus-gdl-adibrofiud-6318-2-babii.pdf

3. Amindyta O. Immature senile cataract in a common 84-year-old woman. Medulla [Internet]. 2013 [cited 2021 Aug 26];1(5):58-64. Available from: https://juke.kedokteran.unila.ac.id/index.php/medula/article/viewFile/149/147