Diabetic Retinopathy Explained – Protecting Your Vision with Early Detection

What is diabetic retinopathy?

Diabetes is a microvascular disease; it affects the small blood vessels throughout the body:

• Feet
• Kidneys
• Heart
• Brain
• And importantly, the retina at the back of the eye

The eye is unique because:

We can see the small blood vessels directly by looking at the retina.

That makes the retina a powerful “window” into what diabetes is doing elsewhere in the body.

Over time, high blood sugar damages the endothelial cells (the cells lining the inside of blood vessel walls). These vessels:

• Become leaky and fragile
• Block off and stop carrying oxygen

When retinal areas lose oxygen (ischaemia), the eye tries to help itself by producing signals that encourage new blood vessel growth.

Unfortunately, in the retina these new vessels are:

• Abnormal and fragile
• Grow along the surface and into the vitreous gel
• Tend to bleed easily
• Lead to scar tissue and traction on the retina

This advanced stage is called proliferative diabetic retinopathy (PDR).

What happens in advanced diabetic retinopathy?

As abnormal vessels and scar tissue develop, several problems can occur:

• Vitreous haemorrhage – bleeding into the gel of the eye
• Bleeding in or under the retina
• Tractional retinal detachment – scar tissue contracts and pulls the retina up
• Distortion and potential damage to the macula, the central area responsible for detailed vision

Patients may experience:

• Sudden loss or clouding of vision from a vitreous haemorrhage
• Gradual distortion or loss of central vision when traction involves the macula
• Severe visual disability if tractional detachment progresses untreated

Our aim at Lowveld Eye Institute is to prevent patients from ever reaching this stage through early detection and timely intervention.

Four key pillars in managing diabetic retinopathy

1. Good blood sugar control

This is always the foundation:

• Improving glucose control does not reverse all existing damage, especially if retinopathy is already advanced. But it reduces the risk of further progression and new complications

Working with your GP, endocrinologist and eye doctor as a team is vital.

2. PRP laser – the mainstay treatment

The primary treatment for proliferative diabetic retinopathy is PRP laser (Panretinal Photocoagulation).

The concept is simple but powerful:

• We sacrifice part of the peripheral retina with controlled laser burn
  • This reduces the retina’s demand for oxygen
• The limited oxygen supply can then adequately serve the more important central retina (macula)
• As a result, the stimulus for new abnormal vessel growth decreases, and the disease stabilises

PRP laser:

• Is usually done as an in-room procedure in the consulting rooms
• Requires a dilated pupil
• Can often be completed over one or a few sessions, depending on the eye

If done early enough, PRP laser often:

• Halts further proliferation
• Prevents vitreous haemorrhage and tractional retinal detachment
• Protects long-term vision

However: once there is dense bleeding or significant traction, it may become impossible to perform PRP adequately; that’s when surgery is needed.

3. Vitrectomy surgery for advanced disease

When diabetic retinopathy is already advanced, laser alone is not enough.

Vitrectomy (vitreoretinal surgery) is indicated in situations such as:

a) Dense vitreous haemorrhage

• The gel of the eye is filled with blood
• We cannot see the retina properly
• Laser cannot be applied because there is no clear view

In vitrectomy:

• We remove the vitreous gel and blood
• Gain a clear view of the retina
• Perform PRP laser internally at the same sitting

b) Tractional retinal detachment/traction threatening the macula

• Scar tissue (fibrovascular complexes) has formed and is lifting the retina
• The macula may already be involved or is under threat

Surgical goals:

• Remove the vitreous
• Carefully peel and release traction and scar tissue
• Flatten the retina
• Apply PRP laser to stabilise the disease

c) Large pre-macular/subhyaloid haemorrhage

• A large pool of blood sits just under the vitreous, directly over the macula
• Can severely affect central vision

Vitrectomy allows us to:

• Remove the gel
• Clear this blood
• Apply PRP laser

In all of these scenarios, vitrectomy is about:

Creating a safe environment in which we can apply adequate PRP laser therapy and stabilise the disease.

4. Intravitreal injections – where they fit in (and where they don’t)

Intravitreal injections (medications such as bevacizumab/Avastin, ranibizumab/Lucentis, aflibercept/Eylea, brolucizumab, etc.) are powerful tools but must be used correctly.

For diabetic retinopathy with neovascularisation:

• Anti-VEGF injections can temporarily regress new vessels

• However, their effect usually lasts about one month

• You need repeated injections to maintain control

By contrast, PRP laser offers a more permanent stabilising effect once adequately applied.

In advanced tractional disease, intravitreal injections can actually be dangerous:

• In eyes where the retina is already being pulled by scar tissue, injections can:
  • Worsen traction
  • Potentially convert a pure tractional detachment into a combined detachment
  • Create new breaks and make surgery more complex
  • Lead to worse visual outcomes

So:

• In proliferative diabetic retinopathy with significant traction and detachment, laser and surgery are the mainstays.
• Injections play a more limited, carefully selected role.

Don’t confuse diabetic retinopathy with diabetic macular oedema

Both are caused by diabetes, but they are different problems:

• Diabetic Retinopathy (DR) – Abnormal new vessels, bleeding, traction, detachment
• Main treatments: PRP laser and, when needed, vitrectomy surgery
• Diabetic Macular Oedema (DMO/DME)
  • Swelling of the macula (central retina) due to leaking vessels
  • Main treatment: intravitreal injections (and sometimes focal/grid laser)

If you’re a diabetic patient already receiving injections, it’s very likely:

• You are being treated for diabetic macular oedema – not necessarily proliferative retinopathy.
• This is an appropriate and evidence-based indication for intravitreal therapy.

Your eye specialist will explain which condition you have and why a particular treatment has been advised.

What does PRP laser mean for your vision?

PRP laser is life-saving for the eye, but it does come with trade-offs:

• Peripheral vision is reduced
• Night vision becomes poorer, because the peripheral retina is key for dark adaptation
• Some patients may lose a small amount of best-corrected visual acuity (a line on the chart), although this is less common

However, without PRP laser in a proliferative diabetic eye:

• The disease would continue to progress
• The risk of vitreous haemorrhage, tractional detachment and severe vision loss is high

So PRP laser is often the lesser of two evils – sacrificing some peripheral and night vision to protect your central vision and prevent blindness.

Why regular eye checks are critical for diabetics

The most important message:

Do not wait for symptoms.
By the time vision is noticeably affected, diabetic retinopathy may already be advanced.

If you have diabetes, you should:

• Have a dilated retinal examination at least once a year with an eye doctor/eye specialist
• Attend more frequent visits if any retinopathy has already been detected
• Work closely with your medical team to improve blood sugar, blood pressure and cholesterol control

Final thoughts

Diabetic retinopathy is serious, but with early detection and appropriate treatment:

• Many patients retain good, functional vision
• We can often avoid complex surgery like vitrectomy
• We can significantly reduce the risk of blindness

If you’re diabetic and haven’t had a proper retinal check recently, consider this your reminder to book an appointment with an eye specialist at the Lowveld Eye Institute. A straightforward examination today might prevent a major problem tomorrow.