Retina Service
How do we see?
Anatomy of Eye
What is retina?
What are the parts of retina?
What are the symptoms of retinal disease?
- Sudden or gradual decrease in
- Loss of field of vision
- Flashes of light
- Floaters
- Objects appearing distorted(Metamorphopsia)
- Night Blindness
When should one consult a retinologist?
What are the diseases that affect the retina?
Common diseases include :
• Diabetes mellitus
• Hypertension
• Age related macular degeneration
• Myopia
• Infectious diseases
• Heriditary degeneration
• Congenital degeneration
• Rarely drugs used for some systemic diseases affect the retina
What are Floaters?
What causes floaters?
When people reach middle age, the vitreous gel may start to shrink, forming clumps or strands inside the eye. Posterior vitreous detachment (PVD) : The vitreous gel pulls away from the retina, causing a posterior vitreous detachment. It is a common cause of floaters. PVD is more common for people who :
• Are shortsighted or myopes ;
• Have undergone cataract operations;
• Have had YAG laser of the eye;
• Have had inflammation inside the eye / any trauma
• Infectious diseases
• Heriditary degeneration
• Congenital degeneration
• Rarely drugs used for some systemic diseases affect the retina
Are floaters ever serious?
The retina can tear if the shrinking vitreous gel pulls away from the retina. This sometimes causes a small amount of bleeding in the eye that may appear as new floaters.
A torn retina is always a serious problem, since it can lead to a retinal detachment. You should see your retina specialist as soon as possible if even one new floater appears suddenly or you see sudden flashes of light or if you notice other symptoms like the loss of side vision.
What can I do about Floaters?
Floaters can get in the way of clear vision, which may be quite annoying, especially if you are trying to read. You can try moving your eyes, looking up and then down to move the floaters out of the way.
While some floaters may remain in your vision, many of them will fade over time and become less bothersome. Once your retina is examined and everything is normal, you can ignore the floaters.
What causes flashes of lights?
What is the treatment of a retinal tear / hole ?
What is Myopia?
• Myopia is also known as shortsightedness.
• It is a disorder in which a person cannot focus distant things clearly.
• The light rays from an object are focused in front of the retina, making them look blurred.
• It is corrected with minus numbered lenses / Lasik surgery.
How does myopia affect the retina?
- Myopia can affect the retina in the following ways
- Myopes have larger eye balls and can develop retinal thinning and degeneration in the peripheral parts of the retina, these occur due to stretching of the globe.
- These degenerations are prone to progress and later may form holes or tears in the retina.
- These retinal holes or tears if not treated can lead to retinal detachment, which will cause sudden loss of vision and will require major surgery at the earliest, to prevent further loss of vision.
- Sometimes the central part of the retina (macula) may be affected by macular degeneration or choraidal neovascular membrane.
How does myopia affect the retina?
It is a micro angiopathy affecting the retinal blood vessels. The main features of diabetic retinopathy are micro vascular (small blood vessel) occlusion and leakage. As a result of this, there is reduced blood supply to the retina .Due to leaking blood vessels, hemorrhages and fluid accumulation in the retina can occur. This initial stage is also called as Non-Proliferative Diabetic Retinopathy (NPDR).
What happens in late stages of Diabetic Retinopathy?
This requires treatment in the form of laser to the eye or surgery or both. The treatment is to stabilize the patient’s vision and prevent further progression of visual loss.
What is Diabetic maculopathy?
Diabetic Maculopathy
Lasered Ratinopathy
- Diabetic maculopathy is the commonest cause of visual loss in diabetic patients.
- Fluid accumulation leads to swelling in the macula which is the area concerned with vision. It may be focal, diffuse or ischemic.
- Focal-focal leakage from the microaneurysms which leads to localized swelling.
- Diffuse-diffuse leakage which leads to swelling throughout the posterior pole.
- Ischemic-in this type the blood supply to the macula decreases and this leads to poor vision.
What are the different investigations done in Diabetic Retinopathy?
Fundus Fluorescein Angiography (FFA)
It also helps us to know whether the patient needs laser photocoagulation or not.
What is the treatment of the Diabetic Retinopathy?
How frequent should a diabetic have eye check up?
Every patient once diagnosed to have diabetes should have regular eye check
ups every 6 months.
AGE RELATED MACULAR DEGENERATION (ARMD)
What are the symptoms of ARMD?
Distortion of lines or objects (Alphabets appear distorted or wavy while reading)
Cloudiness or decrease in central vision.Decrease in colour vision
What are the types of Age related Macular Degeneration?
Dry type (drusen)
Most common cause of vision loss in old age, visual loss is usually gradual. This occurs due to accumulation of a specific material in the ageing cells in the macula as a result of this the cells do not work normally and vision becomes blurred.
Treatment:
Some patients benefit with systemic antioxidant or macronutrient vitamins for the retina
.
Wet Type (choroidal Neovascular Membrane)
This occurs in 10-15% of patients with ARMD but the loss of vision is more profound and may also be sudden sometimes.
This occurs due to formation of a membrane or layer of new blood vessels called Choroidal neovascular membrane (CNVM) which occurs beneath the retina. These new blood vessels can leak blood or fluid that leads to loss of vision and distortion. What are the investigations for ARMD ? FFA and OCT
Can Wet AMD be treated?
- Treatment initiated at the earliest stabilizes the vision.
- Various modes of treatment include:
- Laser photocoagulation
- Photodynamic therapy (PDT)
- Intravitreal injection of Anti-VEGF drugs( Lucentis or Macugen or Avastin)
- Combination therapy or mono therapy will be decided by the retinal specialist.
- Usually a Combination therapy of any two of the above is done
Wet Macular Degeneration
What is Photodynamic therapy?
Photodynamic therapy is performed by injecting a special dye known as Verteporfin. Intravenous verteporfin, selectively localizes in new blood vessels and is activated by laser light on the target area. Non thermal laser energy (diode laser, operating at a wavelength of 689 nm) is then applied locally to the CNVM to produce photochemical reactions that lead to closure of new vessel (thrombosis).
More than one treatment sessions may be required to achieve complete closure.
What are anti VEGF agents?
- Lucentis ( Ranibizumab)
- Avastin (Bevacizumab)
- Macugen (Pegaptanib sodium)
Lucentis /Macugen /Avastin :
These are the latest drugs which have given a ray of hope to improve vision in patient with wet ARMD.These are drugs which prevent the formation of new blood vessels and reduce leakage.
More than one injection may be necessary.
COMPUTER VISION SYNDROME
Introduction :
It wasn’t too many years ago that the primary concerns in thearea of occupational medicine were to prevent traumatic injuries in our industrial plants. Today, occupational health and safety concerns are focused on the office worker, particularly those workers who spend a considerable amount of time at computer displays. Even though these health problems are subtle compared to the serious injuries to which many blue collar workers are exposed, they have become a primary concern in large part because of our shift towards office jobs.
The vision problems at computers result in inefficiencies and in eye – related symptoms. The causes for the insufficiencies and the visual symptoms are individual vision disorders and / or poor visual ergonomics. The symptoms occur whenever the visual demands of the task exceed the visual abilities of the individual. For example, many individuals have marginal vision disorders such as uncorrected refractive errors, accommodative disorders, or binocular vision disorders which are not observed while performing less demanding visual tasks. Likewise, there are numerous aspects of the computer and its work environment
which make it a more demanding visual task than others – therefore, more individuals are put beyond their threshold for experiencing symptoms.