Dr. G. Murali Mohan, senior consultant ophthalmologist and retinal surgeon from Kamineni Hospitals, L. B. Nagar, Hyderabad answers questions related to refractive errors and retinal disorders.
What are refractive errors?
Our eyes are like cameras. They have a film in the form of retina and a focusing system in the form of cornea and lens, which focus the light rays on the retina. The light emerging from the objects we see is made to focus on the retina by the eye's focusing system (cornea and lens). An image of the object is formed on the retina which is then transferred to the brain by means of optic nerves, where the image is perceived. If the light is focused on the retina, we can view the objects we see normally. However, if the light is focused in front or behind the retina, we get a blurred image of the object. This condition is known as refractive error. In case of refractive errors, the focus of light is brought back on retina with the use of glasses, contact lens or by using LASIK treatment.
What are the different types of refractive errors?
There are three kinds of refractive errors that commonly occur in people:
Retinal holes cannot be prevented. However they can be corrected with proper treatment. If they are not treated early, retinal breaks can lead to retinal detachment and blindness.
If the light rays are focused in front of the retina, the condition is known as myopia or near-sightedness. People suffering from myopia can clearly objects that are nearby but face difficulty in viewing distant objects. Myopia can be corrected by using negative powered glasses, contact lenses or through LASIK treatment.
If the light rays are focused behind the retina, the condition is known as hypermetropia or far-sightedness. People suffering from hypermetropia can clearly view distant objects but face difficulty viewing objects that are located nearby. Hypermetropia can be corrected using positive powered glasses, contact lenes or through LASIK treatment.
People suffering from astigmatism have a distorted vision and the objects appear tilted. This condition can be corrected by using cylindrical glasses, contact lenses and through LASIK treatment.
Which is the best treatment method for refractive errors?
LASIK is the best method of treatment for refractive errors. Our cornea is a glass by itself. If we can modify the power of this cornea such that it focuses the light on the retina, then we can get rid of external glasses and contact lenses. The LASIK technique does exactly that. It uses laser to sculpt the cornea, which changes its surface curvature and causes light to be focused on the retina. This procedure provides permanent solution to the problem and causes no serious complications.
What are retinal degenerations and retinal breaks? Does myopia increase the chances of retinal degenerations?
Yes, myopia increases the chances of retinal degenerations. In myopia, the retina is stretched out and thinner than the normal retina. The thin retina gets eroded in some areas. The eroded areas are known as retinal degenerations. These degenerated areas may undergo further erosion ultimately causing the area in the retina to develop holes. Such holes are called retinal breaks.
How does one know whether they have retinal breaks?
Retinal breaks cause no symptoms and we can know about their existence only through tests performed by the retinal surgeon. Occasionaly patients suffering from retinal breaks may experience floaters or flashes of light but these symptoms are seen in very small percentage of patients.
Can retinal holes be prevented? How serious is this condition?
What is retinal detachment?
The retina is attached to the underlying layer in the eye. The seperation of retina from the inner surface of the eye is called retinal detachment. Retinal detachment is a serious disorder that can lead to blindness if left untreated.
What are the factors causing retinal detachment?
Myopia is the major factor responsible for causing retinal detachment. Other factors include:
- Previous cataract surgery
- Severe injury
- Family history of retinal detachment
- Retinal degeneration
Can retinal detachment be prevented?
Yes, retinal detachment can be prevented by regular retinal screening and timely laser barrage to retinal holes.
What is retinal screening and who should undergo this procedure?
Patients with retinal holes do not show any symptoms. It is the retinal surgeon who detects these holes after conducting examination. The retinal examination the surgeon conducts to detect these holes is called retinal screening. In case the holes are detected, he does a laser treatment to seal off the holes. This treatment done to prevent retinal detachment is called Prophylactic laser barrage. Anyone who is suffering from myopia and with a power more than -3 should undergo yearly retinal screening.
How is Prophylactic laser barrage done?
Prophylactic laser barrage aims at creating a barrage (dam or fence) round the dangerous lesions. Laser is passed onto the retina and is welded around the lesions. It is a minor procedure that takes about 10- 15minutes. However, laser barrage does not prevent the development of lesions in other areas. So yearly screening is required even after the procedure to keep a check on the development of retinal holes.
Can retinal detachment be treated? What are the treatment methods adopted?
Prevention is always better than treatment. The treatment methods do not guarantee complete cure.
At present the following methods are used to treat retinal detachment:
A flexible band is placed around the eye to counteract the force pulling the retina out of place. The fluid under the retina is drained off if required. This is an extraocular operation with relatively few complications.
Vitrectomy is an intraocular procedure where the the surgical instruments penetrate the eyeball. Here the vitreous is removed and is replaced with air, fluid or silicon oil.
What are the risk factors involved in retinal detachment surgery?
There is some level of risk involved in every surgery. Retinal detachment surgery has some risk factors like bleeding, cataract, infection, raised intraocular pressure etc. But most of the surgeries in the past have been carried out successfully without any serious complications.
If you want to know more about retinal disorders or want to setup an appointment with the ophthalmologist, visit Kamineni Hospitals, L. B. Nagar, Hyderabad.
You can also check their website here.
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