Introduction 

The eye is a sensory organ comprising many complex parts, all working together to allow you to see your surroundings. 

The World Health Organisation has estimated that globally, at least 2.2 billion people have some form of vision problem or eye-related disease. This article covers a select few of these conditions in depth: macular hole and diabetic retinopathy. 

A macular hole is a small hole that forms in the back of the eye, which causes a reduced or complete loss of central vision.¹ Diabetic retinopathy is a complication of diabetes that leads to the damage of blood vessels at the back of the eye, resulting in partial vision loss.² Some cases of macular holes are the result of poorly managed diabetes and diabetic retinopathy.³

Macular hole 

Causes 

The eye is filled with vitreous humour, a gel-like substance that is connected to the back of the eye (the retina). As you age, the vitreous humour gets thinner and can lose its structural integrity.¹ This causes it to pull away from the retina, creating tension that can eventually cause the central region of the eye (the macula) to tear.¹ This tension is commonly referred to as vitreomacular traction. 

The majority of macular hole cases are idiopathic, meaning they happen spontaneously and have no known cause. However, there are a few known risk factors for macular hole development, including age, sex, and head trauma.⁴ 

Around eight out of every 100,000 people are diagnosed with a macular hole. Individuals assigned female at birth and people over the age of 50 are more at risk of developing this condition.⁵

Symptoms 

The macula is responsible for central vision, which is essentially what you see directly in front of you. Whilst there is no pain when this part of the eye gets torn, your vision may be affected in several ways:⁶

• Reduced central vision
• Blurred vision
• Distorted vision (i.e. straight lines may appear wavy or bowed)
• Spotty vision
• A missing patch 

Diagnosis

There are many different diseases and conditions that affect the eyes, with several of them having overlapping symptoms. Therefore, differentiating between these conditions and reaching an accurate diagnosis can sometimes be challenging. 

For a macular hole diagnosis, an eye specialist will use a process called optical coherence tomography (OCT). This imaging technique uses reflected light to create a cross-sectional image of the layers of the back of your eye.⁶ 

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Treatment 

Vitrectomy 

The most common treatment method for a macular hole is a surgical intervention called a vitrectomy.  This involves removing the vitreous humour to relieve the tension on the retina.⁷ A temporary gas bubble is inflated in the eye to apply pressure to the retina, in order to close the hole.⁷

Vitreous humour does not regenerate. Therefore, as the gas bubble slowly deflates, the eye will produce another solution called aqueous humour to replace the vitreous humour and maintain pressure within the eye.⁸

Vitrectomy surgery has a 90% success rate of macular hole closure, with vision improving in upwards of 80% of patients.^9,10

Ocriplasmin injection 

Another possible treatment for macular holes is an ocriplasmin injection into the eye. This is a viable option if the cause of the condition is known to be vitreomacular traction. 

This injection helps to separate the vitreous humour from the retina to reduce the tension and allow the hole to heal over.¹¹ 

Ocriplasmin injections occur under local anaesthetic and are usually only offered in the early stages of macular hole development.¹¹

What is diabetes? 

Diabetes is the umbrella term for conditions in which there is excess sugar in the blood due to the body making insufficient or ineffective insulin.¹² The table below discusses the major types of diabetes are:¹³

Diabetic retinopathy 

Causes

Diabetic retinopathy is a direct result of poorly managed diabetes. The eye is supplied with nutrients and oxygen by lots of tiny blood vessels. Individuals with diabetes have high blood sugar, and over time this excess sugar damages the blood vessels.² 

As a result, the amount of oxygen and nutrients delivered to the eye is reduced. The eyes can sometimes attempt to grow new blood vessels, but these are almost always underdeveloped. Consequently, these vessels can pull the retina away from the back of the eye and leak into the vitreous humour.¹⁴ It is the growth of these leaky blood vessels that causes vision problems in people with diabetic retinopathy. 

Stages

Diabetic retinopathy is a disease that presents itself in several stages, which can be spotted at diabetic eye screening appointments. These three stages are:²

Diagnosis 

If you have diabetes, you are encouraged to have regular eye screening appointments to look out for diabetes-related eye diseases, like diabetic retinopathy. They are a good way to spot eye problems before any vision problems arise. 

These screening appointments involve dilating your pupils with eye drops, and then looking directly into a camera that takes a photo of the back of your eye. 

An eye specialist will review the photos to assess whether there have been any changes since the last appointment and will look out for any signs of retinopathy. If there have been no changes and no signs of disease, another screening appointment isn’t needed for 2 years. 

Treatment 

As diabetes is so closely linked to food consumption, controlling diet and administering the correct amount of insulin is a vital part of managing the disease across all of its stages. 

Treatments tend to be offered once retinopathy significantly impacts vision, which is often once retinopathy reaches the proliferative stage.¹⁴

Anti-VEGF injections 

Vascular endothelial growth factor (VEGF) promotes the growth of new blood vessels. However, after development in conditions like diabetes where high sugar levels and reduced oxygen are present, VEGF release is increased. This promotes the growth of new and underdeveloped blood vessels.¹⁵

Anti-VEGF injections into the eye are a treatment option available to patients with diabetic retinopathy, to reduce the growth of new leaky blood vessels. These aim to prevent your vision from getting worse.

Laser photocoagulation

Laser photocoagulation involves directing lasers to the new underdeveloped blood vessels in the eye, with the aim of preventing further growth. This also reduces the amounts of VEGF released by the eye.¹⁴

This type of therapy can be completed in one sitting and has been shown to reduce the risk of severe vision loss by around 50%.¹⁶

Summary 

A large proportion of the population faces vision problems at some point during their life, whether this is due to ageing or disease. Whilst the symptoms of macular holes can be daunting, the available treatments have proven to be successful in both reattaching the retina and regaining visual acuity. Although high blood sugar is damaging to all blood vessels throughout the body, its impact on the eye and vision is particularly significant.  Whilst there are available treatments for diabetic retinopathy, the management of diabetes is key in disease prevention. 

Everyone is encouraged to have regular eye screening appointments - especially those who are at a higher risk of eye disease and vision problems, including the elderly and those with diabetes.