Senile cataract is a vision-impairing disease caused by age, and it is characterized by the gradual progressive thickening of the lens in the eye. This disease is the world’s leading cause of treatable blindness, which is unfortunate, as age-related cataract is reversible. Due to this fact, early detection, careful and attentive monitoring, and timely surgical intervention must be taken into consideration to manage this disease.
In the developed world, treatment is more accessible. However, economically disadvantaged and geographically isolated regions suffer greater challenges as healthcare access is limited. Depending on the extent of damage to the lens of the eye, the disease is classified by several types/stages of senile cataract.
What are the stages of senile cataract?
Cortical senile cataract
This type of cataract occurs in the cortex of the eye. Patients will experience decreased levels of total proteins, amino acids, and potassium as well as an increased concentration of sodium and marked hydration of the lens. This is followed by the coagulation of proteins.
Nuclear senile cataract
Degenerative changes from the previous stage begin to intensify. Age-related nuclear sclerosis associated with compaction of the nucleus and dehydration result in a hard cataract. However, the total content of protein and distribution of cations remain normal.
Immature senile cataract (ISC)
In this stage, opacification progresses even more. The lens now appears greyish white, but clear cortex is still present, creating an iris shadow. For some patients in this stage, the lens may swell due to continued hydration. This condition is known as “intumescent cataract.”
Mature senile cataract (MSC)
Opacification becomes complete at this stage, involving the whole cortex. The lens turns pearly white in color, and this cataract is known as “ripe cataract.”
Hypermature senile cataract (HMSC)
Hypermaturity sets in at this stage when the mature cataract is left in the situ. This cataract may occur in two forms: morgagnian hypermature cataract or sclerotic type hypermature cataract.
Prevalence of senile cataract
Out of the 2,477 patients examined in the Framingham Eye Study from 1973–1975, senile cataract was seen in 15 percent of the group. The overall rates of each of its types/stages increased with age. The most commonly seen lens change was nuclear opacities.
In 2004, an updated study was conducted by the Wilmer Eye Institute. Researchers noted that approximately 20 million Americans older than 40 years had a cataract in either eye. By 2020, this number is expected to rise to 30 million cataracts. An average of three million Americans has cataract surgery annually, with a success rate of 95 percent, correcting vision to 20/20-20/40 at best.
What are the causes of senile cataract?
Many studies have been conducted over the years to discover the causes of senile cataract and to identify risk factors for its development. Some of the causes discovered include environmental conditions, systemic diseases, diet, age, and UV exposure. Age-related cataract is a multifactorial disease with various risk factors associated with each different type of senile cataract. Also, cortical and posterior subcapsular cataracts were related closely to environmental stresses including diabetes and drug ingestion. Nuclear cataracts were more connected with smoking. Research has also shown that alcohol use is associated with all cataract types. Additional causes of senile cataracts include the following:
- Exposure to radiation from outer space (ex. commercial pilots)
- Long-term exposure to UV rays
- Microwave radiation
- Iodine deficiency
- Eye injury and physical trauma
- Eye allergies
- Long-term usage of corticosteroids and drugs containing Quetiapine
Symptoms of senile cataract
Routine ocular examinations can spot signs of opacity of the lens. Although other symptoms may not be present, this is an effective way to get early diagnosis and treatment. Common symptoms of cataract include the following:
This is one of the earliest visual disturbances in patients developing a cataract. Glare is also associated with the intolerance of bright light, such as sunlight or the headlights of an oncoming vehicle. Depending on the location and size of the opacity, some patients will experience more glare or dazzle than others.
This symptom is defined as the doubling or trembling of objects and is also one of the earlier symptoms of this disease. Irregular refraction of the lens due to variable refractive index leads to this symptom.
Patients often perceive this symptom as the breaking of white light into a colored spectrum due to the presence of water droplets in the lens.
Black spots in front of eyes
These spots are stationary and may be perceived by some patients with cataracts.
Image blur or distortion/misty vision
Loss of vision:
Senile cataract often leads to visual deterioration. This symptom is painless and progresses gradually with age. Patients who experience central opacities have early vision loss and see better when the pupil is dilated due to dimmer light in the evening. Patients with peripheral opacities have delayed vision loss, and vision is improved in the daylight when the pupil is contracted. In patients with nuclear sclerosis, distant vision begins to deteriorate because of progressive index myopia.
How to diagnose senile cataract
There are various examinations and tests that specialists can conduct to look for signs to diagnose senile cataract. A complete ocular examination must be conducted, and this process begins with observing visual acuity for both near and far distances. If the patient is experiencing glare, the visual acuity test should be performed in a bright room. If the history points to a possible problem, contract sensitivity must also be evaluated. The diagnosis of senile cataract can also include the following:
- Examination of the ocular adnexa and intraocular structures
- Swinging flashlight tests
- Slit lamp examinations
- Examination of nuclear size and brunescence
- Direct and indirect ophthalmoscopy
If an adequate view of the back of the eye is challenged by a dense cataract, deeper tests such as ultrasonography, computed tomography (CT) scanning, or magnetic resonance imaging (MRI) may be conducted.
Complications of senile cataract
- Phacoanaphylactic uveitis: Typically develops between one day and two weeks after traumatic or surgical perforation of the lens capsule. Symptoms of this complication maybe include severe sensitivity to light, pain, decreased vision, eye redness, floaters, and epiphora.
- Lens-induced glaucoma: Subdivided into two major categories. The open-angle category is related to the leakage of lens proteins through the capsule of a cataract that is in the mature or hypermature stage. The angle-closure category related to lens swelling or dislocation.
- Subluxation or dislocation of lens
Treating senile cataract
To delay, prevent, or reverse the development of senile cataracts, FDA-approved and clinically proven medical treatment methods are needed. Unfortunately, there is no such treatment available. However, aldose reductase inhibitors have shown promising results in preventing sugar cataracts in animals. How effective this medical treatment is for humans is still to be determined.
To definitively manage senile cataracts, surgical lens extraction is performed. Modern phacoemulsification provides the advantage of a smaller size incision upon cataract surgery. Results of this surgery may pose the risk of poor visual outcomes if the following factors are present: short-term postoperative complications, surgical complications, ocular comorbidity, and complex surgery.
Prognosis of senile cataract
Since senile cataract develops with age, it is a slowly progressive disease. If surgery is needed to treat a patient, lens extraction will improve the visual acuity in more than 90 percent of cases. The remainder either suffered from pre-existing retinal damage or developed serious postsurgical complications. Postsurgical complications could include glaucoma, retinal detachment, vitreous hemorrhage, infection, or epithelial down-growth into the anterior chamber, which hinders visual improvement.
Patients who have undergone surgical operations to treat cataract can obtain corneal contact lenses that help them adjust to their new world of sight with greater ease. These lenses allow almost normal vision, without the magnification, distortion, and diminished peripheral vision that cataract glasses can cause.
While there are modern medical and surgical treatments for senile cataract, the disease has its own limitations and complications. Natural nutritional therapy is also an emerging and cost-effective treatment as a way to prevent senile cataract and establish precautionary protection against the disease.
Related: Nuclear cataracts: Causes, symptoms, and treatment