Introduction

Cataracts are the leading cause of blindness worldwide and can only be treated by surgery.¹ As you age, cataracts can naturally appear as the proteins on the surface of the lens break down. These can form clumps that cause the eye to look cloudy.²

Age-related macular degeneration (AMD), on the other hand, is another major cause of blindness. It is caused by the progressive deterioration of the macula, which is located at the back of the eye and contains many photoreceptors that help you see. 

Both conditions occur with age and can occur simultaneously. In this article, we will examine their common risk factors and discuss how they can be managed and prevented. 

Understanding cataracts

Causes and risk factors

The ageing process is a natural and primary cause of cataract formation. The lens is a small disc inside the eye. Over time, the fibres inside the lens structure become clumpy, making it less transparent. This can lead to vision loss.³

Additional risk factors include:

• A family history of cataracts
• Alcohol misuse
• Diabetes
• Eye injuries
• Prolonged steroid use
• Smoking

Symptoms of cataracts include blurred vision, faded colours, and light sensitivity. They are not usually painful but can be in the later stages of the disease.⁴

Types of cataracts

There are 5 different types of cataracts that people can get:

• Age-related conditions, which appear after the age of 40
• Congenital or paediatric, when children are born with them or develop them due to genetic conditions
• Radiation, as a result of ultraviolet light (UV) exposure or radiotherapy for cancer
• Traumatic, when cataracts form from injuries to the eye
• Secondary, occurring when scar tissue after a cataract causes blindness again⁵

They might also be classified according to the location of the cataract. Nuclear sclerotics involves cataracts that form in the centre of the eye, cortical cataracts affect the cortex (outer layer) of the lens, and subcapsular cataracts form just under the lens. 

Treatment options

Surgery remains the most effective treatment for cataracts once they reach a point where they interfere with daily life. The lens is taken out and replaced with a new one, which is clear and allows you to see. It is a short procedure, lasting 45 minutes maximum, and is performed under local anaesthesia. As of yet, no non-surgical treatments such as eye drops can slow or prevent cataract formation. ⁶

What is age-related macular degeneration (AMD)?

Age-related macular degeneration (AMD) is a similar condition affecting the eye, causing central vision loss. Like cataracts, it is able to affect one or both of the eyes. It does not cause any noticeable changes to the eyes, but it is possible to have cataracts and AMD at the same time. 

Upon examination, the defining feature of AMD is drusen or drusen bodies – small, yellow deposits of proteins and fats (lipids) in the macula. This is part of the thin layer at the back of the eye, known as the retina. Although not a cause of AMD, the presence of certain types of drusen bodies can be indicative of progression to later stages of the disease.⁷

Causes and risk factors

Ageing is the major contributor to AMD, and a few other risk factors have been identified, such as:

• A genetic predisposition, with a higher likelihood if other relatives have AMD
• Smoking
• Poor diet and nutrition

Symptoms of AMD include seeing blurred spots or nothing in the centre of your vision, with normal edges. It can also cause straight lines to appear crooked. Individuals with AMD might also experience difficulties with facial recognition.⁸

Types of AMD

There are two types of AMD:

• Dry AMD (also called atrophic AMD) is when the macula thins with age. Occurs in 3 stages
• Wet AMD, or advanced neovascular AMD, causes rapid vision loss; dry AMD can become wet AMD, which is the late-stage form of the disease featuring abnormal blood vessel growth at the back of the eye

In early AMD, there is no vision loss, but drusen deposits might be present. The intermediate stage of AMD features large drusen and some blindness, but this can vary. Late-stage dry or wet AMD can lead to vision loss.⁹

Treatment options

Wet AMD treatments stop the disease from getting worse. Anti-VEGF (vascular endothelial growth factor) injections can stop blood vessels from growing and further damaging the macula. 

Laser therapy, or a combination of medication and laser therapy known as photodynamic therapy, might be used, but these usually have more side effects. In exceptional cases, surgery may be the only option to remove blood vessels that result from wet AMD.

Nutritional supplementation might slow the progression of the disease in early stage AMD. Increasing one’s intake of vitamin C, vitamin E, zinc, copper, and beta-carotene can help people who have large drusen deposits. ⁹,¹⁰

The link between cataracts and AMD

There is some correlation between cataract surgery and the progression of AMD, but the link between the two is still unclear. Mixed findings have been reported, with some or no relationship shown between cataracts and AMD. 

Does cataract surgery impact AMD?

Some theories as to why cataract surgery can impact AMD include phototoxicity (light toxicity) to the eyes, causing harm in the form of free radicals or reactive oxygen species (ROS). These are unstable molecules, causing adverse effects when they interact with DNA and other chemicals inside your body. When cataract surgery is performed, the removal of the cataract can lead to the retina being exposed to UV light. 

Inflammation might also lead to the worsening of AMD after cataract surgery. To heal after an operation, your body can signal for blood vessels to form at the site of the wound. This allows more oxygen and nutrients to be delivered for recovery. An excess of blood vessels may, however, cause harm to the macula. 

Despite this, cataract surgery still has major benefits for the quality of life of individuals with either condition. It can help people to see more clearly. ¹¹People with both cataract and AMD can experience severe visual impairments, so it is important to manage both conditions, especially in the elderly. 

Preventive measures and eye health tips

It is possible to slow the progression of conditions such as AMD and cataracts with proper eye care. Looking after the eyes after cataract surgery can also help to promote good eye health. Listed below are some general factors to consider:

• Stopping smoking
• Management of blood pressure with diet and exercise
• Eating a balanced diet that includes adequate levels of vitamins and micronutrients
• Shielding the eyes from UV rays with sunglasses
• Regular eye check-ups at the optometrist to monitor eye health

Current research and future directions

Higher quality research needs to be done to fully understand whether there is any risk of AMD progression following cataract surgery. Conclusions cannot be drawn from mixed results, and it is important to make sure that other factors do not interfere with finding a relationship between the two. 

New insights into cataract surgery and its effects can help direct innovations in clinical practice. If a link is found, it might also drive research into new AMD drugs or preventative treatments. It might also be helpful to look into the genetic and environmental factors that cause either condition. 

Summary

Cataracts and AMD are two conditions that can occur from ageing, affecting vision loss in two different ways. They have different treatments, and the progression of AMD has been observed after cataract surgery (currently the only treatment available for the condition).

The link between cataract surgery and AMD is still unclear, so more research is needed to understand whether it contributes to AMD worsening or not. 

Preventative measures such as consuming a balanced diet rich in nutrients and proper eye care practices can mitigate the risk of cataract and AMD onset.