Diabetic retinopathy is the most common cause of vision loss in Western working-age adults (Shukla & Tripathy 2021). In fact, among the 1.7 million Australians who have diabetes, about one-third are estimated to have some degree of diabetic retinopathy (CERA 2020).

What is Diabetic Retinopathy?

Diabetic retinopathy (DR) is a microvascular disorder caused by long-term diabetes, characterised by gradual vision-threatening damage to the retinal blood vessels (Shukla & Tripathy 2021).

If left untreated, DR can result in irreversible blindness (Dirani et al. 2013).

What Causes Diabetic Retinopathy?

DR is associated with chronic hyperglycaemia and occurs when excess glucose obstructs the blood vessels in the retina, cutting off their blood supply (Shukla & Tripathy 2021; Mayo Clinic 2021).

There are two stages of DR:

1. Non-proliferative diabetic retinopathy is the initial stage of the condition and is characterised by the weakening of the retinal blood vessels. This causes the blood vessels to thin and bulge outwards, and consequently, they may leak fluid and bleed into the retina.
2. Proliferative diabetic retinopathy is the more advanced, serious stage of DR. It occurs when new, abnormal blood vessels begin to grow in response to the reduced blood supply to the existing blood vessels. These new blood vessels are very fragile and may leak into the vitreous humour. This can cause the formation of scar tissue that may pull on the retina and lead to retinal detachment.

(myDr 2018; Mayo Clinic 2021; Dirani et al. 2013)

Macular oedema, wherein fluid leakage from the retinal blood vessels causes swelling of the macula, can occur in any stage of DR. This may impair central vision, which is used for tasks such as reading and driving (Better Health Channel 2015; myDr 2018). Macular oedema is the most common cause of vision loss in diabetes (Dirani et al. 2013).

Risk Factors for Diabetic Retinopathy

All people with type 1 and 2 diabetes are at risk of DR. However, effectively controlling diabetes reduces the likelihood (Vision Initiative 2021).

As a general rule, the longer the patient has had diabetes, the greater the risk of developing DR (CERA 2020).

Factors that might increase the risk of DR include:

• Having diabetes for longer than 10 years
• Going through puberty
• Pregnancy (due to increases in hormones)
• Hypertension
• Obesity
• Dyslipidaemia (lipid imbalance)
• Poor diabetes management
• Nephropathy (diabetic kidney disease)
• Genetics
• Increased inflammatory factors
• Apolipoprotein (a plasma protein)
• Hormones (leptin and adiponectin)
• Vitamin D deficiency
• Oxidative stress
• Being an Aboriginal or Torres Strait Islander Person.

(myDr 2018; Shukla & Tripathy 2021; Payne et al. 2012; Mallika et al. 2010; Rübsam et al. 2018)

Symptoms of Diabetic Retinopathy

There are typically no symptoms in the early stages of DR (CERA 2020). In advanced stages, patients might experience:

• Blurry, distorted or patchy vision that can’t be corrected with prescription lenses
• Eye floaters (specks that appear to move across the field of vision), which may have a red or brown tinge
• A smudge in the vision of one eye
• Difficulty reading, watching television or recognising faces
• Pain in one or both eyes
• Difficulty seeing straight lines (may appear bent or wavy)
• Sensitivity to glare
• Difficulty seeing at night
• Balance issues.

(Healthdirect 2020; CERA 2020; Vision Initiative 2021)

Complications of Diabetic Retinopathy

Potential complications of DR include:

• Vitreous haemorrhage, which can temporarily fill the vitreous cavity and block vision Retinal detachment, which can result in severe vision loss
• Glaucoma
• Blindness.

(Mayo Clinic 2021)

Diagnosing Diabetic Retinopathy

Regular eye examinations, early diagnosis and treatment are essential to try to prevent severe vision loss. This includes a baseline eye examination when diabetes is first diagnosed (Better Health Channel 2015).

DR is diagnosed through an eye examination that typically comprises digital retinal photography and a dilated eye exam. In this exam, eye drops are used to dilate the eyes so that the practitioner can get a better view of the eye using a slit lamp or ophthalmoscope to examine for evidence of DR (CERA 2020; myDr 2018).

Treatment for Diabetic Retinopathy

DR can’t be cured, but if detected early, management strategies can be used to prevent vision loss before any damage is done. If the patient has already experienced vision loss due to DR, treatment can stop it from worsening but may be unable to restore vision that has been lost (Diabetes Australia 2021; myDr 2018).

The best way to prevent vision loss is the effective management of diabetes, including:

• Regular eye examinations
• Maintaining a healthy lifestyle
• Maintaining a healthy and balanced diet
• Regular physical activity
• Managing blood pressure and cholesterol.

(Dirani et al. 2013)

Treatment is typically indicated when DR is in a proliferative stage, or macular oedema is present. It might involve one or more of the following:

• Retinal laser treatment to help prevent further vision loss and reduce the risk of worsening
• Intravitreal injection, which involves injecting medicine (either a vascular endothelial growth factor inhibitor or steroid) directly into the vitreous - injections may be required regularly
• Vitrectomy (surgical removal of the vitreous).

(CERA 2020; Dirani et al. 2013)

Preventing Diabetic Retinopathy

The best way to prevent vision loss from DR is for all people with diabetes to undergo regular eye examinations, as damage can usually be avoided if DR is detected early enough (CERA 2020).

It’s essential that people with diabetes undergo an eye examination:

• When they are first diagnosed with diabetes, and
• Every two years thereafter (annually for Aboriginal or Torres Strait Islander Peoples), and
• Immediately when they notice any changes in their vision.

(Vision Initiative 2021)

In order to increase the number of people with diabetes undergoing regular eye checks, Diabetes Australia and Vision 2020 Australia have established an eye check reminder program called KeepSight.

For more information, see KeepSight’s website.

References