What is the cause of cataracts?
A cataract is a lens abnormality characterized by decreased transparency and increased cloudiness affecting one or both eyes.
The lens of the human eye functions in a similar way to the lens of a camera. It is made primarily of proteins called crystallins which are responsible for the lens refractive function.
Modification, accumulation, and precipitation of crystallins are the main mechanisms underlying cataract development. Changes in the arrangement and alterations in the character of the lens proteins result first in increasing rigidity of the lens, and eventual loss of transparency.
Most cataracts are caused by age-related degeneration; however, a cataract can also develop secondary to trauma or as a consequence of another disease. Other causes for cataracts include a range of drugs that may be used in certain doses for a long duration.
The development of a cataract is accelerated by conditions such as diabetes mellitus. Diabetic individuals develop cataracts approximately 20 years earlier and undergo cataract surgery for visually significant cataracts at a much younger age than people without diabetes. Cataracts rarely occur in children and if they do, they are most likely congenital, meaning they are present from birth.
How cataracts are graded
Cataracts are defined by where the opacities (cloudiness) are in the lens and graded by how severe the opacities are in that area.
- Subcapsular- opacity in the posterior (backside) capsule of the lens
- Nuclear – opacities are in the center of the lens
- Cortical – Swelling of the lens cortex causing peripheral cloudiness.
Generally, the nuclear cataract which covers the center of the lens will be graded as mild, moderate, pronounced, or severe. The other two types, subcapsular and cortical are graded by the percentage of space obscured since they only partially cover the lens.
There are various forms of grading systems used to designate how severe are the opacities. A retinal specialist will use the system that they have been trained with or have found to be the most practical.
Having a consistent grading system helps patients who may have difficulty explaining how much their vision is worsening. An accurate grading system helps the retinal specialist determine how much the patient’s cataracts opacity has changed, if at all, during subsequent visits.
When is cataract surgery needed?
The cure for cataracts is surgery. However, this surgery is not appropriate for everyone and may not produce equal outcomes.
There can be contraindications where surgery should not be used because it may be harmful to the patient. If surgery is done, it may only partially restore vision if there are comorbid ocular diseases such as diabetic retinopathy or glaucoma.
Decisions have to be made, according to the circumstances, about how much cataract is enough to warrant surgery, how it should be performed and delivered, and how it should be paid for.
However, all and all, cataract surgery is the most common procedure in the world and also one of the safest. Your retinal specialist will help determine if cataract surgery is beneficial for your eyesight. They may also encourage you to have surgery if the cataract’s opacity prevents them from monitoring an ocular disease such as diabetic retinopathy.
It is your decision
Modern cataract surgery is so successful that in the majority of cases, it’s really a matter of the patient’s wishes. There are no specific cut-offs for surgery based on visual acuity. Some patients will want cataract surgery at a very early stage because they wish to reduce their requirement for glasses at the same time.
Once the cataract is substantial and the patient’s vision can no longer be improved with eyeglass correction, the cataract can be surgically removed and replaced with a synthetic intraocular lens (IOL) using laser-assisted technology.
Others will prefer to put off surgery and avoid any potential complications until they’re really struggling.
So, it’s a very personal decision when cataract surgery is carried out. The usual reasons are the blurring of vision to the degree a patient is comfortable entering a hospital and have a surgical procedure.
Surgery options
Laser therapy
Retinal tears can be treated with lasers with an effect of the laser called “photocoagulation.” The retinal specialist will numb your eye with anesthetic eye drops and focus the laser on the retinal tear or small detachment.
The laser light travels and burns the area around the retinal tear or detachment to create a scar. Scar tissue seals the tear or reattaches a detached portion of the retina to underlying tissue.
This laser therapy prevents fluid from going underneath the retina, which is the cause of a detached retina. The majority of retinal tears are treated with laser photocoagulation.
Photodynamic laser therapy
For age-related macular degeneration (AMD) Photodynamic laser therapy (PLT) is one type of treatment. The retinal specialist injects a special medicine into your arm which travels and collects in the abnormal (damaged) blood vessels under your macula.
The light from the laser is shown into your eye which activates the medicine. This creates blood clots in your abnormal blood vessels sealing them off helping to prevent more vision loss.
Photodynamic laser therapy can’t restore lost vision; however, it can slow down the damage to your central vision. It can also be used for other ocular medical conditions.
Submacular surgery
Submacular surgery is a procedure to remove scar tissue that is growing under the retina and other associated hemorrhages. This scar tissue can cause deep visual loss in patients with age-related macular degeneration. Called subretinal choroidal neovascular membranes (SRN), they were formed in previous attempts to repair some ocular condition. Once removed, vision can often be improved.
Retinal translocation
Retinal or macular translocation is a surgical procedure where the retinal specialist detaches the retina and relocates it to a healthier place in the eye for those with macular degeneration (MD). The surgery is not recommended for every patient suffering from MD. It’s best performed on patients in the early stage of the disease, and it’s only meant to treat the wet form of MD, where leaking blood vessels have formed beneath the retina.
