A cataract is the most common cause of preventable blindness worldwide. It is defined as the normal clouding of the lens due to the deposition of lens proteins. A cataract is primarily an age-related condition, with most people above eighty suffering from the same. Females are more prone to cataracts than their male counterparts. A cataract is more prevalent in Americans, followed by Blacks. Hispanics are the least affected by cataracts.

What Is the Normal Anatomy of the Eye Lens?

The eye lens is a biconcave crystalline structure of fibers enclosed in a lens capsule membrane. It is located behind the pigmented part (iris) of the eye. The primary function of the lens is to focus all the light towards the retina of the eye.

What Causes the Clouding of the Lens?

Opacification of the lens is a normal aging phenomenon seen in the eyes of the elderly. Sometimes, the cataract may also be present in youngsters; inapparent pathologies cause it.

Conditions that are linked to the formation of cataracts are:

Congenital.
Traumatic. Damage to the lens occurs due to several traumatic conditions such as,
- Blunt trauma.
- Ultraviolet radiation.
- Electric shock.
- Physical and chemical injuries.
Systemic diseases linked to cataract formation include:
- Neurofibromatosis 2.
- Myotonic dystrophy.
Endocrine diseases involved in cataract formations are:
- Diabetes.
- Hypoparathyroidism.
Ocular diseases include:
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- Highly shortsightedness.
- Hereditary fundus dystrophy.
Corticosteroids and anticholinesterase inhibitor drugs play a vital role in the opacification of the lens.
Deficiency of vitamins and antioxidants.
Smoking.
Alcoholism.

What Is the Mechanism Behind the Clouding of the Lens Seen in a Cataract?

The lens is made of two main parts.

Firstly, the outer cortex is made up of younger fibers.
Secondly, the nucleus is made up of older fibers.

Several mechanisms together cause the breaking up of the fibrous lens proteins, which get deposited in the lens, resulting in the lens's clouding. The clouding of the lens obstructs the light from passing through it, thus compromising the vision. The mechanisms involved in the process of cataracts formation include:

Disturbances in the lens growth.
Differently formed lens fibers.
Pigmental depositions of the lens.

What Are the Types of Cataracts?

Based on the region of lens affected, it is of two types:

Cortical cataract.
Nuclear cataract.

What Are the Clinical Signs and Symptoms to Look Out for in Patients Suffering From Cataracts?

The main symptoms reported by patients with cataracts are:
- Blurred vision.
- Double vision.
- Rainbow halos around the light.
- Glare to light.
- Frequent change of refractive glass.
- Yellowing of the objects.
The signs of cataracts to look out for by ophthalmologists are:
- Decrease in visual acuity. The reduced visual acuity might be present in one eye or both eyes.
- There is a presence of wedge-shaped opacity in the lens's periphery, resulting in greyness in the advanced stages. It is seen in cortical cataracts.
- Cortical cataracts also present with swollen lenses due to fluid accumulation. In addition, the iris shadow is absent.
- Blacks lens with an iris shadow is observed in nuclear cataracts.
Certain systemic conditions present with typical clinical signs of cataract:
- Diabetes shows snowflake-like opacities in the lens.
- Myotonic dystrophy has Christmas tree-like opacification, which later becomes wedge-shaped.

How Are Patients With Cataracts Diagnosed?

The diagnosis of cataracts involves complete history, comprehensive physical examination, and investigations.

A detailed history of the patients regarding their eye symptoms and systemic conditions is acquired.
Physical examination of the eye involves the monitoring of:
- Visual acuity.
- Refraction.
- Squint.
- Responses of the pupil.
- A complete examination of the adnexal (near eye) structures is carried out.
- Evaluation of the transparent part (cornea), lens, and anterior chamber of the eye is conducted.
Thirdly, various investigative tests are performed to rule out any other ocular pathology and form an appropriate diagnosis. For example, the tests used for cataracts include:
- Darkroom tests.
- Fundoscopy.
- Biometry.
- Macular function test.
- Peripheral retinal assessment.
- Ultrasonography.
Tests for ruling out other systemic pathologies are known as the baseline tests. The baseline tests include liver function tests, blood sugar, complete blood count, chest X-ray, and hepatitis.

What Are the Various Approaches Used in Treating Patients With Cataracts?

The centerpiece of cataract treatment remains surgery. However, the treatment modality chosen depends on the disease severity and its cause.

The other treatment modalities are:

Medical therapy is initiated in patients with a visual acuity of 6/24 or more. Patients are administered Phenylephrine, Atropine, or cataract drops. Refractive glasses are also recommended in some cases.
Surgery is the treatment of choice if the eye acuity is less than 6/24 and another ocular complication is associated. The surgical technique includes complete irrigation and removal of the lens with reimplantation of the new lens.

Congenital cataracts do not require treatment if the visual acuity is more than 6/24. In the case of cataracts caused by other systemic conditions, treatment of the basal problem is essential.

What Are the Conditions That Mimic Cataracts?

Several conditions show similarities with cataracts. The other similar conditions include -

Glaucoma.
Refractive errors.
Diabetic retinopathy.
Macular degeneration.

Cataracts can cause complications if left untreated. Complications are also observed post-cataract surgery. The most prominent difficulty of cataracts is blindness.

Other complications include:

Glaucoma.
Retinal detachment.
Inflammation of the iris.
Dislocation of the lens.
Posterior capsule thickening.
Post-operative infections.
Secondary cataract.

Is It Possible to Prevent Cataracts?

The prevention of cataracts is possible only by a team effort by the public and healthcare professionals.

Patient education about the disease, its causes, treatment options, and complications are as vital as prompt diagnosis and referral by the primary care worker. Patients are advised to wear sunglasses to avoid ultraviolet rays.

What Is the Prognosis of Cataracts?

Several factors like the severity, other diseases, mode of treatment, and timing of the treatment are responsible for determining the condition's prognosis. Cataract has an excellent prognosis after surgical correction. However, patients are advised to keep a regular follow-up to prevent secondary cataracts.

Conclusion

Cataracts remain the leading cause of preventable blindness worldwide. People with cataracts often suffer from the underlying systemic condition. In addition, the slowly progressive nature of the disease often delays prompt diagnosis and treatment. Nevertheless, an excellent prognosis is possible with surgery.