Distorted Vision: Vitreomacular Retinal Diseases

KWOK Kwan Ho, Alvin

Honorary Consultant in Ophthalmology

Specialist in Ophthalmology

Macula is located at the center of the retina. It contains a large number of light-sensitive cells, allowing us to see fine details, read and distinguish colours. It is also important for our central vision.

Macular diseases are myriad. With the aging population and increasing incidence of myopia, the number of people with macular diseases has been on the rise in recent years in Asia. All macular diseases must be diagnosed and treated at the earliest opportunity, otherwise severe consequences may result. Major symptoms include blurred central vision, distorted images and difference in size of images between eyes. As no symptom may occur if the condition is found in one eye only or progression is slow, a thorough eye examination is recommended starting at the age of 40.

Macular Neovascularization

Macular neovascularization refers to abnormal blood vessel growth in the macula. The blood vessels are prone to leakage and bleeding, scarring, and damage to vision is irreversible if it is not treated in time. 

The condition was once treated with the same medication used in targeted therapy against colonic cancer. As cancer will lead to the growth of abnormal blood vessels which seize nutrients for their own growth, the purpose of medication is to constrict and regress the abnormal blood vessels so as to cut off the nutrients to the cancer which will lead to its necrosis. Such medication is applied to macular neovascularization as they share similar pathology of growth of abnormal blood vessels.

Nowadays anti-VEGF agents are frequently used to treat macular neovascularization by way of injection every 1 or 2 months and possibly once in a few months once the condition stabilizes. Research showed that significant improvement of vision was noted in about 1 out of every 3 patients after treatment. Patients with the following types of macular neovascularization can receive injection in a clinic setting:   

• Macular neovascularization due to age-related macular degeneration: it is common in people aged 55 or above, with damage to macula cells caused by aging, UV exposure or cardiovascular diseases, which in turn leads to degeneration and abnormal blood vessel growth.
• Macular neovascularization due to high myopia (above 600 degrees): it is common in youth with macula being stretched thin by elongated eyeball.

Anti-VEGF agents are also used to treat macular edema caused by retinal vein occlusion/diabetic maculopathy, and abnormal blood vessel growth due to diabetic retinopathy.  

Other treatment options include photodynamic therapy, laser photocoagulation, intravitreal steroid injection etc, depending on the patient’s condition.

Macular Edema

Macular edema is categorized as primary and secondary, and the abovementioned belong to the latter. Primary macular edema (Idiopathic Central Serous Chorioretinopathy) is found in patients with thick uvea vessels, which, being prone to leakage, can cause fluid accumulation in the retina. Other associated factors include stress, insomnia, frequent caffeine consumption, steroid use (oral, nasal spray, skin ointment), and hormone medications. Macular degeneration, or even abnormal blood vessel growth, may occur in severe cases.

Epiretinal Membrane (ERM) / Macular Hole

Epiretinal membrane (ERM) is common in Hong Kong. It refers to the abnormal growth of another layer of cellular membrane over the macular surface. With a wrinkled macula, ERM patients have distorted and blurred central vision. Primary ERM is common in people with high myopia and the elderly due to degeneration.

Secondary ERM usually occurs in people with a history of retinal tear or detachment, eye trauma, diabetic retinopathy, retinal vein occlusion, intraocular inflammatory diseases, etc.

A macular hole is a small gap or break at the centre of macula. It is mostly age-related or caused by severe myopia.

Thanks to technological advance, both ERM and macular hole can now be treated by surgery with a very high success rate. Most patients do not need to face down after surgery.

Floaters & Retinal Detachment

The jelly-like substance filling the space between the crystalline lens and the retina is called vitreous humour. The vitreous humour degenerates and liquefies and then contract as we get older and begin to see some floating opacities known as “floaters”. Floaters can be of various sizes or shapes e.g. dots, circles, lines and webs. They usually appear suddenly and may occur in greater numbers, which is related to vitreous contraction that can also cause flashes. Because of the pulling on the retina, it may cause bleeding within the vitreous humour, retinal tear or even retinal detachment. They are more obvious when looking at bright homogenous backgrounds such as a white wall or the blue sky, and mostly remain unchanged over time.

Both floaters and flashes are hence symptoms of vitreous contraction that may lead to retinal tear, and mostly indicate retinal detachment if accompanied with peripheral visual field defects. Retinal tear may lead to retinal detachment if not treated promptly. Whenever there is a sudden onset of floaters or flashes, arrange dilated eye examination with an Ophthalmologist immediately.

Diagnosis of Vitreomacular Retinal Diseases

During optical coherence tomography (OCT), a safe, low energy pin-point near infrared laser beam is projected and scanned across the designated area of the macula. In a non-invasive manner, posterior segment OCT system can analyse the layered structures of the macula and help ophthalmologists and patients understand the pathology of the diseases.

Self-Test of Central Visual Field – Amsler Grid

Cover one eye at a time and focus on the dot at the center. It may indicate macular problems if the lines appear wavy, distorted, shadowed or disappeared. Arrange eye examination with an ophthalmologist immediately in case of any visual disturbance.  

Left Pic - Normal Macula Function      

Right Pic - With Age-related Macular Degeneration

(From reading distance or with reading glasses)

(The above pictures are for reference only, and should not be used for self-test purpose.)

Who are at Risk of Vitreomacular Retinal Diseases?

• Age ≥ 55 years old
• Patients with diabetes
• High myopia (above 600 degrees)
• Repetitive physical impact to the eyes, which is common among professional athletes
• A family history of related diseases

Preventing Macular Degeneration

• Wear sunglasses to prevent cataract and pterygium
• Do not smoke
• Prevent or treat cardiovascular diseases