Our Services - Vitreomacular Retinal Diseases
What Are Floaters?
The jelly-like substance filling the space between the crystalline lens and the retina is called "vitreous humour". The vitreous humour degenerates and liquefies when we get older, at which time we start to see floaters. Floaters can be moving opacities of various shapes and sizes (dots, circles, lines or spider webs). Physiological floaters usually occur when we are looking at a bright homogenous background such as a white wall or the blue sky. The floating opacities are few in number and remain unchanged over time. They represent normal physiological changes of the vitreous humour.
Pathological floaters appear suddenly and may occur in great numbers. They may suggest bleeding within the vitreous humour, inflammation of the uvea or separation of the posterior vitreous humour from the retina. If the floaters are accompanied by flashes or visual field defects, it may indicate retinal tear or retinal detachment. An ophthalmologist should be consulted immediately to distinguish the causes of these conditions.
Vitreous degeneration and floaters
Flashes, Acute Posterior Vitreous Detachment and Retinal Detachment
As we age, the vitreous humour undergoes the processes of synchysis (liquefying) and syneresis (dehydrating and shrinking). These are normal agerelated degenerations. When the vitreous humour contracts and detaches from the retina, it is called acute posterior vitreous detachment (acute PVD), at which time sudden onset of floaters and flashes occur. Floaters can be caused by vitreous opacities or haemorrhages, whereas flashes are caused by the vitreous humour pulling on the retina. An urgent dilated eye examination is essential to check for retinal tears, which should be repaired with laser as soon as possible, to prevent it from evolving into retinal detachment within a few hours.
Posterior vitreous detachment
Retinal tear and detachment
What Are the Symptoms of Retinal Detachment?
- Increased floaters
- Increased flashes
- Visual field loss
- Visual distortion or disturbance
Treatment for Retinal Detachment
Retinal degenerations or tears can be repaired with laser while retinal detachment is treated with surgery. There are two main types of retinal detachment surgery, namely scleral buckle, which is performed around and outside the eyeball, and vitrectomy (with gas or silicone oil injection), which is performed inside the eyeball. Both of the surgeries include laser treatment or cryotherapy.
Who Are at Risk of Retinal Detachment?
- Middle-aged persons with PVD which causes retinal tear
- Eyes with retinal lattice degenerations, atrophic holes or horse-shoe tears
- High myopes (higher than –6.0 Dioptres)
- Ocular or orbital trauma
- Previous intraocular surgery (e.g. cataract or glaucoma surgery)
- Certain inherited diseases (e.g. Marfan's Syndrome, Stickler's Disease)
- Family history of retinal detachment
- Diabetic retinopathy
- Retinopathy of prematurity, etc
Regular Eye Examinations Can Preserve Vision
Please schedule regular eye examinations with your ophthalmologist.
Peripheral retinal degeneration and retinal tear
The Latest Development in Maculopathy Treatment
The retina is like a camera film: it functions by capturing the light from objects. The image directed onto the retina is then transmitted to the brain where it is processed. Structurally speaking, the retain is more like a part of the brain with no capacity for self-repair or transplantation. In the centre of the retina is the macula, which is responsible for central and colour vision. If left undiagnosed and untreated, all types of maculopathies can lead to severe consequences, e.g. blurred central vision, central visual field defects or distorted images. Some conditions are asymptomatic, especially when they affect one eye only or are in slow progression. Thanks to the advances in clinical technology and a better understanding of macular diseases, those that were considered incurable in the past can now be treated by surgery.
Treatment of Macular Hole
A macular hole is a break of optic nerve tissues in the centre of macula. It is mostly age-related or caused by severe myopia. The standard treatments are subtotal pars plana vitrectomy with removal of the posterior hyaloid, followed by removing the internal liniting membrane (Photo 1) and gaseous and fluid exchange. Most patients are not required to maintain a face down posture post-operatively. The success rate is over 90%.
Photo 1: During surgery (the right eye of patient from the surgeon's perspective):the internal limiting membrane near the macular hole (arrow) is lifted(arrow)using an intraocular forceps.
Treatment of Proliferation of Macular Epiretinal Membrane
Proliferation of macular epiretinal embrane (Photo 2) is one of the common eye diseases in Hong Kong, the treatment of which is to remove the vitreous body and epiretinal membrane. Outcome can be improved with internal limiting membrane removal. The recurrence rate after first surgery is low.
Photo 2: Macular epiretinal membrane disease in a patient with severe myopia (before surgery).
Treatment of Maculoschisis
Those with myopia of over 600 degrees have severely elongated eyeballs, which stretch thin the macula. The macular split could be aggravated due to further stretching by abnormal vitreous body and epiretinal membrane, leading to loss of vision. The split might deteriorate into macular holes (Photo 3A) and even macular retinal detachment if left untreated. With OCT, it can now be detected and diagnosed in its early stage with high accuracy(Photo 3B). The treatment is pars plana vitrectomy with removal of the posterior hyaloid, epiretinal membrane and internal limiting membrane followed by gas injection. They can resolve maculoschisis in most patients. Most patients are not required to maintain a face down posture post-operatively.
Photo 3: Optical Coherence Tomography(OCT): (A)extensive macular split, macular detachment and loss of macular depressions are detected under OCT before surgery (arrow) (B)Macular split improves significantly 6 months after surgery.
Treatment of Neovascular Membrenes caused by Age-Related (Photo 4) and Severe Myopic (Photo 5) Macular Degeneration
Photodynamic therapy was once the standard treatment of neovascular membrene caused by age-related and severe myopia macular degeneration. It has a limited effect of maintaining the remaining vision or deterring vision loss. Currently, intraocular injection(incl. Lucentis, Avastin, Eylea and steroids)is the common practice. It can restore vision to a certain extent in most patients. The procedure is safe. Side effects are rare.
Photo 4:Age-related macular
degeneration - bleeding
Photo 5:Severe myopia macular degeneration