RETINA

The retina is a very important structure in the eye, composed mainly of nerve fibers which allow the images we see to be transmitted to the brain. There are some common systemic conditions, such as diabetes which can affect the retina and the macula resulting in poor vision for the patient. Other conditions such as age-related macular degeneration may also result in poor vision for the patient.

Diabetic Eye Screening

As diabetes is a chronic condition, patients may develop diabetic eye disease in the long run. Patients who are not compliant to keep their blood sugar levels low may be at a higher risk of developing diabetic eye disease as well. Diabetic eye disease can present itself through a few ways. They include diabetic macular edema, diabetic retinopathy, vitreous haemorrhage, neovascular glaucoma and cataract.

Therefore, patients who have already been diagnosed with diabetes are highly recommended to have their eyes screened.

Diabetic Eye Diseases

Diabetic retinopathy is caused by retinal ischaemia where there is lack of blood supply to the retina which results in formation of weak new blood vessels and leakage of blood vessels. This will result in bleeding of the eye and swelling of the retina.

Vitreous haemorrhage is when the leaked blood in the retina flows to the clear gel like substance (vitreous) of the eye.

Diabetic macular edema or diabetic maculopathy is when there are leakages of blood vessels and swelling of the macula. This is the most common cause of poor vision in a patient as the macular is part of the retina that gives us good vision.

Neovascular glaucoma develops in eyes with late stages of diabetic eye disease. The eye responds to the lack of blood supply to the eye by producing abnormal new blood vessels at the front part of the eye, typically seen on the iris and obstructing the fluid drainage channel of the eye. This would cause complications such as pressure build up in the eye, resulting in a severe optic nerve damage.

Diabetes can lead to cataract formation in the eye as uncontrolled diabetes causes sugar levels to increase in the aqueous fluid and affecting the lens. This would then lead to progressive blurring of vision over time.

Long-term diabetes and poorly controlled diabetes can cause reduced blood flow to the eye. This may result in the ischaemia of the optic nerve.

Management of Diabetic Retinopathy

The approach to the management of diabetic retinopathy is to first detect it. During the eye screening, Dr Jimmy Lim would be able to perform tests to detect presence of diabetic retinopathy and macular edema even before the patient begins to notice any symptoms in the vision. Therefore, it is important for patients to undergo eye screening at least once a year.

For patients who have been diagnosed with retinopathy or maculopathy, it is important to have a tighter control of their diabetes.

Patients will need various types of lasers to decrease the risk of severe vision loss and vitreous hemorrhage, and treatment includes the use of intravitreal anti-VEGF eg. Ranibizumab (Lucentis) injection to decrease the swelling of the macular and improve the patient’s vision.

Even after treatment, it is essential for patients to keep their diabetes in control and have regular follow-ups with the eye specialist to monitor the progression of the disease.

Age-Related Macular Degeneration

Age-Related Macular Degeneration (AMD) mainly affect older patients, with them complaining of distortion or loss of central vision. This is because of degeneration to the macular (center part of the retina) may result in loss of good central vision.

Types of Age-Related Macular Degeneration

Age-Related Macular Degeneration can be classified into dry and wet AMD.

Dry AMD usually have no visual symptoms to mild visual symptoms and it is detected upon examination by an eye doctor. It is detected with drusen which can be seen over the macular and there may be a thinning (atrophy) of the macular area. Dry AMD may progress to wet AMD if it goes undetected.

Wet (Exudative) AMD have visual symptoms that range from mild to severe loss of central vision. There may be swelling of the macular and even bleeding at the macular area. The nerve fibre layer of the retina can be detached and there may also be vitreous haemorrhage.

Polypoidal Choroidal Vasculopathy (PCV) also presents with signs and symptoms similar to wet AMD. Visual symptoms can range from mild to severe loss of central vision. There may be swelling of the macular and bleeding at the macular region. Detachment of the nerve fibre layer and vitreous haemorrhage can also be seen.