Know the Diseases :
The main eye related problems are :
3) Diabetic Retinopathy
4) Retinal Detachment
6) Dry Eyes
Know the Diseases :
The main eye related problems are :
3) Diabetic Retinopathy
4) Retinal Detachment
6) Dry Eyes
Human Eye: The basic structure of the human eye is like a camera. In a normal eye, light rays pass through the “Cornea” & “Lens” and get focused exactly on the “Retina”. In our eyes, the “Lens” is the important part of the eye that helps to focus light on the “Retina”. The retina is the eye’s light-sensitive layer that sends visual signals to the brain via Optic Nerve. So to produce a sharp image, the lens must remain clear.
Cataract: The Lens, Which is responsible for focusing light and producing sharp images, is a clear tissue located behind the pupil – the dark circular opening in the middle of the iris or colored part of the eye. The Lens works with the transparent cornea, which covers the eye’s surface, to focus light on the retina at the back of the eye. When the lens becomes cloudy, light cannot reach to the retina properly, and vision is blurred and decreased. This can start to cloud small areas of the lens, blocking some light from reaching the retina and interfering with vision. This is called a Cataract. So cataract is formed when the natural lens of the eye becomes cloudy and hardens, resulting in loss of visual function.
Causes of Cataract:
Everyone is at risk of developing cataracts simply because age is the single greatest risk factor. Other Important factors are:
- Family history of cataract
- Previous eye surgery
- Prolonged use of corticosteroids
- Excessive consumption of alcohol
- Excessive exposure to sunlight
- Exposure to high levels of radiation, such as from cancer therapy
Types of Cataract:
Age-related cataract: Most cataracts are related to aging.
Congenital cataract: Some babies are born with cataract or develop them in childhood, often in both eyes. These cataracts can affect vision and impair the visual growth of the eyes. If they do so, they may need to be removed.
Secondary cataract: Cataracts are more likely to develop in people who have certain other health problems, such as diabetes. Also, cataract are sometimes linked to long term steroid use.
Traumatic cataract: Cataracts can develop soon after an eye injury, or years later.
Here are some signs of a cataract:-
- Cloudy, fuzzy, foggy, or filmy vision
- Changes in the way you see colors.
- Problems while driving at night because headlights seem too bright.
- Problems with glare from lamps or the sun.
- Frequent changes in your eyeglass prescription.
- Double vision.
- Better near vision for a while only in farsighted people.
How to Diagnosize Cataract?
To detect a cataract, an eye care professional examines the lens. A comprehensive eye examination usually includes:-
Visual acuity test: Acuity refers to the sharpness of your vision or how clearly you see an object. In this test, your eye doctor checks to see how well you read letters from the chart across the room. Your eye are tested one at a time, while the other eye is covered. Using the chart with progressively smaller letters from top to bottom (the standard snellen chart), your eye doctor determines of you have 20/20 (6/6) vision or less.
Slit-lamp examination: A slit lamp allows your eye doctor to see the structures at the front of your eye under magnification. The microscope is called a slit lamp because it uses an intense beam of light, a slit, to provide oblique illumination of the cornea, the iris, the lens and the space between the iris and cornea. The slit allows your doctor to view these structures in cross section and detect any small abnormalities.
Retinal examination: In this procedure, your eye doctor puts dilating drops in your eyes to open your pupils wide and provide a bigger window to the back of your eye. Using a slit lamp or ophthalmoscope, he or she can examine your lens for signs of a cataract and, if needed, determine how dense the clouding of the lens is. He or She will also check for glaucoma and, for other problems involving the retina and the optic nerve. Dilating drops usually keep your pupils open for a few hours before their effect gradually wears off. Until then, you probably will have difficulty focusing on close objects, but your distance vision shouldn’t be affected.
Tonometry: This is a standard test to measure fluid pressure inside the eye. Increased pressure may be a sign of glaucoma.
Other eye tests may also be used occasionally to show how poorly you see with a cataract or how well you might see after surgery. These tests are:
- Glare test
- Contrast Sensitivity Test
- Potential Visual Acuity Test
- Specular Photographic Microscopy Test
How cataract can be treated?
- For an early cataract, vision may improve by using different eyeglasses, magnifying lenses, or stronger lighting. If these measures don’t help, surgery is the only effective treatment. This treatment involves removing the cloudy lens and replacing it with an artificial lens. A cataract needs to be removed only when vision loss interferes with your everyday activities, such as driving, reading, or watching TV.
- Surgery is the only option for cataract. Neither diet nor medications have shown to stop cataract formation. Cataract surgery is now a frequently performed operation in most parts of the world.
Cataract surgery Methods:
There are two primary ways to remove a cataract:
- Phaco-Emulsification, or Phaco (Misnomered as ‘Laser’): Your doctor makes a small incision on the side of the Cornea, the clear dome-shaped surface that covers the front of eye. The doctor then inserts a tiny probe into the eye. This device emits ultrasound waves that soften and break up the cloudy center of the lens so that it can be removed by suction. Most cataract surgery today is done by Phaco, which is also called small incision cataract surgery or Suturless surgery. Since the incision is made in a valvular fashion with the help of special keratomes, there is no need to take stitches & the incision takes only a couple of hours to heal.
- Extra capsular surgery: Your doctor makes a slightly longer incision on the side of the Cornea and removes the hard center of the lens. The remainder of the lens is then removed by suction. An artificial lens is then implanted and the cut is then stiched up with very thin suture material.
In a cataract operation, the eye’s natural lens is removed. In most cataract surgeries, the removed lens is replaced by an artificial Intra Ocular lens (IOL). An IOL is a clear, artificial lens that requires no care and becomes a permanent part of your eye. With an IOL, you’ll have improved vision because light will be able to pass through it to the retina. For some people with eye disease in whom IOL cannot be implanted, a soft contact lens may be suggested. For others, glasses that provide powerful magnification may be better.
The artificial lens is made of plastic and is usually inserted at the same time the cataract is removed. Once the surgeon has determined that intraocular lens replacement is appropriate, the patient undergoes a special preoperative evaluation. Like contact lenses and “prescription” eyeglasses, intraocular lenses differ in terms of refractive power and the evaluation will determine the proper lens power of the implant. The length of the eye is measured and the curvature of the cornea is evaluated. Calculation of the implant power is based on this information and performed on a computer called, A-scan Biometry or Sonography.
Generally speaking, overall cataract surgery lasts about an hour and is usually performed on an outpatient basis. After a brief rest following surgery, the patient generally returns home the same day, in most of the cases without a Bandage too (More so if the surgery is done under topical anesthesia & a foldable lens is implanted.)
Types of Intra-Ocular Lens
What is Glaucoma?
Glaucoma is a disease where the pressure inside the eye is raised to the extent that it may cause visual damage. So it is an abnormally high fluid pressure within the eye. As pressure builds, it can “pinch” both the optic nerve and the blood vessels, which nourish the retina. The result is usually a slow loss of peripheral, or vision, and eventual blindness. So Glaucoma is the leading preventable cause of blindness.
Generally our eye needs a certain amount of pressure to keep the eyeball in shape so that it can work properly. In some people, the damage is caused by raised eye pressure. Others may have an eye pressure within normal limits but damage occurs because there is a weakness in optic nerve. In most case both factors are involved but to a varying extent. Eye pressures is largely independent of blood pressure.
Types of Glaucoma:
Following are a few types of Glaucoma:-
- Open Angle Glaucoma
- Closed Angle Glaucoma
- Secondary Glaucoma (precipitated by other factors)
- Primary glaucoma (glaucoma originating without secondary causative factors)
- Juvenile Glaucoma (children)
- Congenital glaucoma (meaning from birth)
In Open-angle glaucoma. The transparent fluid inside the eye (Aqueous Fluid) cannot be drained quickly enough, because the drainage channels (Trabecular meshwork) within the eye have become restricted. Open-angle glaucoma is often inherited from parents, although this is rarely the case with Closed-angle glaucoma.
In Closed-angle glaucoma, the angle or periphery of the anterior chamber of the eye is closed and so the eye cannot drain the fluid quickly enough.
The most common is chronic glaucoma (chronic = slow) in which the aqueous fluid can get to the drainage channels (open angle) but they slowly become blocked over many years. The eye pressure rise very slowly and there is no pain to show there is a problem, but the field of vision gradually becomes impaired.
Acute glaucoma (acute = sudden) happens when there is a sudden and more complete blockage to the flow of aqueous fluid to eye. This is because a narrow ‘angle’ closes to prevent fluid ever getting to the drainage channels. This can be quite painful and will cause permanent damage to your sight if now treated promptly.
Childhood glaucoma is a rare form of glaucoma that often develops in infancy, early childhood, or adolescence. Prompt medical treatment is important in preventing blindness.
Congenital glaucoma, a type of childhood glaucoma, occurs in children born with defects in the angle of the eye that slow the normal drainage of the fluid. Prompt medical or surgical treatment is important in preventing blindness.
Both open-angle and angle-closure glaucoma can be classified as primary or secondary. Primary glaucoma cannot be contributed to any known cause or risk factor.
Both open-angle and angle-closure glaucoma can be classified as primary or secondary. Secondary develops as a complication of another medical condition or injury. In rare cases, secondary of another medical condition or injury. In rare cases, secondary is a complication following another type of eye surgery.
Symptoms of Glaucoma:
Symptoms may include:
- Frequent mild headache, especially upon waking;
- Increased difficulty with night vision;
- Recurring redness in one or both eye, especially if accompanied by blurred vision and/or pain;
- A frequent change of eyeglass prescription;
- A noticeable loss of peripheral vision.
- Severe pain, pain, foggy vision and rainbow haloes.
If your experience there symptoms, seek treatment immediately.
Main Cause for Glaucoma:
The main underlying reason why increased intra ocular pressure develops (glaucoma) is because the outflow of intra ocular fluid gets impaired (obstructed) in one way or another. This leads to increased pressure of the fluid inside the eye.
- Anyone can develop glaucoma, however, it is rare in people under 45 year of age. The people, who run the highest risk of developing glaucoma, are people who have a close blood relative who have suffered glaucoma. (E.g. mother, father, sister or brother)
- Certain eye conditions are more prone to developing glaucoma :-
- People who are very short- sighted
- Detachment of the Retina
- Certain illnesses of retina e.g. Retinitis pigmentosa
- Also, Patient with diseases of the thyoid gland.
- Patient with Diabetes mellitus (impaired sugar tolerance)
Detection & Diagnosis of glaucoma:
Glaucoma can only be detected through a series of tests performed by your eye doctor. The loss of vision is usually so gradual and painless that most people are unaware of it until damage is permanent. Once vision has been lost due to glaucoma, it cannot be restored. If you are over 45 years of age, your eye surgeon will use an instrument called a “Tonometor”. This instrument takes a pressure reading from your eye by placing the machine on your eye (Applanation or Schiotz Tonometer) or by firing a puff of air (Pneumotonometer).
In addition to a complete medical history and eye examination, your eye care professional may perform the following tests to diagnose glaucoma:
- Visual acuity test – the common eye chart test, which measures vision ability at various distances.
- O.P. Measurement – Either by Schiotz Tonometer (lying down position) or by Applanation or Pneumotonometer (sitting position on the slit lamp)
- Pupil dilation – the pupil is widened with eye drops to allow a close-up examination of eye’s retina & optic nerve head.
- Gonioscopy – To see the angle of the eye with the help of 3 or 4 mirror Gonioscope.
- Visual field – a test to measure a person’s side (peripheral) vision. Lost peripheral vision may be an indication of glaucoma.
In a simple, painless test, doctor measures the fluid pressure or “hardness” of the eye manually high or if the optic nerve proves abnormal upon examination, your doctor will probably suggest you undergo a “visual fields” test to determine if any peripheral or side vision has been lost.
Treatment of Glaucoma:
In glaucoma is detected, it can be treated one of three ways: with medications, conventional surgery or lasers. Traditional treatment includes eye drops and tablets to control fluid pressure. These drugs will reduce the production of the transparent fluid within the eye. This relieves the pressure from within the eye and prevents damage caused by Glaucoma. If medication is ineffective, either laser or conventional surgery will be used to open channels in the eye through which fluid may drain.
“The best defense against glaucoma is regular eye checkups by a qualified eye care specialist.”
- LASER: The laser, actually an intense beam of light, produces short bursts of precisely directed energy to create fluid channels within the eye. A typical laser treatment takes 15 minutes or less and requires only eye drops for anesthesia. Blurred vision for an hour or so after surgery is usually the only discomfort. The laser is not a “cure” for glaucoma, but it often makes it possible to avoid surgery and reduce dependence on medications. If laser and medical treatment fails to bring glaucoma under control, conventional glaucoma surgery to open a drainage channel will almost certainly be required.
- TRABECULAR SURGERY: This method is used to improve the drainage of fluids from your eye. The “trabecular meshwork” is fine net of fiber between the cornea and the iris. If fluid is blocked from passing through this net, pressure on the eye build, pinching the optic nerve. The surgery is usually done under local anaesthesia. The usual surgical time is around 30-35 minutes. Bandage is kept for a day or two depending on the healing. Slight pricking or watering & redness following surgery, will be there for 5-7 days. Though the complication rate is less, but few complications viz. bleeding, failure of surgery or loss of vision may be expected in less than 1% of cases.
Normal Vision: The Retina is the nerve cell layer of the eye and acts much like film in a Camera. When light enters the eye it passes through the cornea and Lens and is focused onto the Retina. The Retina transforms the light energy into vision and sends the information back to the brain through the optic nerve. The macula is the sensitive, central part of the retina and is responsible for sharp, detailed vision.
Diabetic Retinopathy results from the effects of the diabetes on blood vessels that nourish the Retina tissue, which is the innermost layer of the eye wall. It is mainly associated with diabetes and is caused by the blockage if tiny blood vessels in the retina, casing hemorrhages on or in the retina. Diabetes causes retinal blood vessels to leak and grow abnormally. Untreated diabetes or poor disease maintenance greatly increases the risk of diabetic retinopathy. Depending on the severity of the disease, sight can remain near normal or may be lost entirely. Remaining vision may be blurred or distorted or the hemorrhage may cause a deep reddish veil over the field of vision.
Types of Diabetic Retinopathy:
There are two main types of Diabetic Retinopathy:
In Non-Proliferative or Background Diabetic Retinopathy, patients may have normal vision. The damaged retinal vessels leak fluid. Fat and protein particles may leak from these vessels and become deposited in the retina in patches know as Retinal Exudates. The retinal blood vessel may bleed into the retina and result in tiny hemorrhages. If any of the leaking fluid accumulates in the central part of the retina (called the macula), the vision is affected. This condition is called Macular Edema.
In Proliferative Diabetic Retinopathy, new abnormal blood vessels grow, which extend over the surface of the retina. These vessels occasionally invade the gelatinous contents of the eye, the vitreous. The proliferating blood vessels frequently break, causing vitreous bleeding that may significantly decrease vision. Fibrous tissue may grow over the new blood vessels and distort vision. Occasionally, the tissue may contract and pull the retina off the inner surface of the eye, causing a tractional retinal detachment.
There are no symptoms in the early stages of diabetic retinopathy. Vision may not change until the disease is advanced or the Macula is affected. The earliest sign may be an abrupt change in eyeglass prescription. The blood sugar effects the water content of the lens of the eye and therefore, spectacle prescription changes. Sudden increase in blood sugar will cause an increase in myopia. This often occurs before the detection of the disease. Diabetic Retinopathy may begin in eyes without one noticing any change in vision. Unfortunately, there may be extensive and severe changes before vision is affected. Thus, it is very important to have the eye examined regularly at six-month or yearly intervals depending on duration and/or severity of the diabetes.
Detection of Diabetic Retinopathy:
Diabetic retinopathy is detected during an examination of the back of the eye Fundoscopy through dilated (enlarged) pupils and by testing your vision. Dilatation is the method through which, after putting some eyedrops, we can method through which, after putting some eyedrops, we can see what is inside, to properly evaluate the Retina. We look for evidence of Diabetic Retinopathy. Based on the findings a Fluorescein Angiogram may be advised.
Fundus Fluorescein angiography (FFA):
Fluorescein Angiography is a dye test often used to assess the damage to the retina and its blood vessels. A dye is injected into a vein of one arm. Photographs are taken of the retina as the dye passes through the blood vessels. Since there is a risk of allergic reaction, a history is important. There may be mild nausea during the procedure. The skin and urine may turn yellow for 24 to 48 hours. These Angiograms show areas of leakage, areas of oxygen – starved retinas, and weak fragile new vessels. Based on the results a LASER may be advised.
The most important treatment for diabetes and its complications including diabetic retinopathy is control of the diabetes. Tight control of blood sugar, weight and blood pressure are important is preventing the ocular complications of diabetes and thus slowing the progression of the disease.
One retinopathy is diagnosed, Laser therapy is the current modality of treatment. Most patients tolerate the procedure extremely well with little discomfort. Laser surgery is used to treat both diabetic macular edema and proliferative diabetic retinopathy. Laser treatment for diabetic macular edema stabilizes vision by stopping blood vessels form leaking fluid into the retina. Either focal treatment for small discrete areas of leakage is there or a grid pattern is used when is used when the leakage is diffuse in nature. After treatment, the patient may notice small spots of decreased visual sensitivity in the field of vision. Usually these spots become less noticeable with time. It is possible that the vision may get a little worse after laser. However, the laser helps prevent further reduction in vision. Studies have shown that most patient who receive laser for macular edema will have better vision in the future than if they hadn’t received the treatment. After instilling an anesthetic drop in the eye, the retina is treated with LASER using suitable Laser delivery system.
In Retinal detachment, the retina separates from the outer layers of the eye thus losing its function. If not treated early, retinal detachment may lead to impairment or complete loss of vision.
Most retinal detachments are preceded by one of more tears or holes in the retina. Fluid passes through these opening and separates the retina from the adjacent layers of the eye. Near-sighted individuals are more commonly affected due to thinning of the retina. Holes or tears can then develop in the thinned retina. The vitreous (gel fluid in the eye) also plays a significant role by causing tugging on the retina especially when shrinkage occurs. Cataract surgery can also be a precipitating cause. A positive family history of retinal detachment is another risk factor. A combination of factors is usually responsible for retinal detachment. Retinal detachment can also be caused by other diseases in the eye such as tumours, severe inflammations, or complications of diabetes.
Middle-aged and older persons may see floating black spots called floaters and flashes of light. In most cases, these symptoms do not indicate serious problems. In some eye the sudden appearance of spots or flashes of light may herald the onset of retinal detachment. A through examination of the retinal by an ophthalmologist after dilatation of the pupil is necessary to determine the cause of the symptoms. Some retinal detachments can proceed unnoticed until a large section of the retina is detached. In these instances, patients may notice the appearance of dark shadow in some parts of their vision. Further development of the retina detachment will blur central vision and create significant sight loss in the affected eye. A few detachments may occur suddenly and the patient will experience a total loss of vision in that eye. Similar rapid loss of vision may also be caused by bleeding into the vitreous which may happen when the retina is torn.
If the retina is torn but detachment has not yet occurred, prompt treatment may prevent the occurrence of a complete detachment. Once the retina becomes detached, it must be repaired surgically.
- Laser Photocoagulation:
When new small retinal tears are found with little or no nearby retinal detachment, the tears are sometimes sealed with a laser light. The laser places small burns around the edge of tear. These produce scars that seal the edges of the tear and prevent fluid from passing through and collecting under the retina.
- Freezing or Cryopexy:
Freezing through the sclera (white of the eye) behind a retinal tear will also stimulate scar formation and sealdown the edges.
- Surgical Repairs:
Successful reattachment of the retina consists of sealing the retinal tear with a silicone material, which is sutured to Sclera (white of the eye) to indent the eyeball inwards. Freezing applications are then used to bind the retina to the underlying layers.
Newer Procedure have been developed to achieve the same result using the injection of a gas into the eye in suitable cases. The surgery may be performed under local or general anesthesia depending on the procedure, age and general health of the patient. In more complex retinal detachments, it may be necessary to use a technique called vitrectomy. This operation removes the vitreous body from the eye. In some cases, when the detached retina itself is severely shrunken or scarred, air of gas may have to be used to fill the vitreous cavity temporarily.
Over 90% of all retinal detachments can be reattached by modern surgical techniques. Occasionally, more than one operation may be required.
The degree of vision, which finally returns about six months after successful surgery, depends upon a number of factors. In general, there is less visual return when the retina has been detached for a long time of if there is fibrous growth on the surface of the retina.
Approximately 40% of successfully treated retinal detachments achieve excellent vision. The remainder attains varying amounts of reading vision.
Due to continuous shrinkage of the vitreous and the development of fibrous growths on the retina. Not all retinas can be attached. If the retina cannot be reattached, the eye will continue to lose sight and ultimately become blind.
What is Refractive Error?
The cornea is a part of the eye that helps focus light to create an image on the retina. It works in much the same way that the lens of a camera focuses light to create an image on film. The bending and focusing of light is also known as Refraction. Usually the shape of the cornea and the eye are not perfect and the image on the retina is out-of-focus (blurred) or distorted. These imperfections in the focusing power of the eye are called Refractive errors.
Type of Refractive Errors:
There are three primary types of refractive errors: Myopia, Hyperopia and Astigmatism.
- Myopia (Near-Sightedness) :-
In a “Myopic” eye, the light rays are passed through the “Cornea” & “Lens”, but point at which they get focused is in front of “Retina”. This configuration allows clear image of near objects, but not those that are far away. Normally, it occurs, when “Cornea” is too curved or eye is too long.
- Hyperopia (Far-Sightedness) :-
In case of “Hyperopic” eye, light rays after getting passed through “Cornea” & “Lens”, focus at a point beyond the “Retina”. In such case, patients can focus more on distant object, but not images that are close to hand. It occurs when cornea is too flat or the eye ball is too short.
- Astigmatism :-
With Astigmatism, the rays of light do not focus into a single point but form a line on Retina. This occurs when Corneal curvature is irregular in different meridians.
Types of Refractive Surgery:
Various types of Refractive Surgery that are used to reshape the “Cornea” are:
- Radial Keratotomy (RK)
- Photo Refractive Keratotomy (PRK)
- Laser In-Situ Keratomileusis (LASIK)
- In “RK”, very sharp knife is used to cut slits in the “Cornea” changing its shape.
- “PRK” was the first surgical procedure developed to reshape the cornea, by sculpting, using a laser. It involves removal of the top surface layer of the cornea called the epithelium. This exposes the inner cornea (stroma), which the computer assisted laser will begin to resculpt, thereby altering the curvature of cornea.
- Later the “LASIK” was developed. The same type of Laser is used for both “LASIK” & “PRK”. The major difference between these two procedures is the way in which the stroma (the middle layer of “Cornea”) is exposed before it is vaporized with the laser. In “PRK”, the top layer of “Cornea” (called Epithelium) is scraped away to expose the stromal layer underneath, while in “LASIK”, a flap is cut in the stromal layer & the flap is folded or replaced back.
What is Lasik?
Lasik is the acronym for “Laser In-Situ Keratomileusis”. It is a surgical procedure that is capable of correcting a wide range of “Near-sightedness” , ”Far-sightedness” & “Astigmatism” by the use of laser to reshape the “Cornea” without invading the adjacent cell layers. This correction procedure utilize two devices i.e. the Excimer Laser and the Microkeratome . The Microkeratome, a precise instrument that is the “Keystone” in the LASIK procedure, is a mechanical shaver that contains a sharp blade that moves back and forth at high speed. This shaver is placed in the guide tracks of the suction ring and is advanced across the cornea using gears at a controlled speed. This process creates a partial flap in the cornea of uniform thickness. The flap is created with a portion of the cornea left uncut to provide a hinge.
Lasik is the latest Refractive surgery technique that can benefit a great number of people with Myopia, Hyperopia & Astigmatism. Candidates who have a strong desire to reduce a lifetime dependence on glasses & contact lens can go for Lasik.
Comparision of Refractive Surgery:
Neither LASIK nor PRK involves any pain during the procedure itself. Patients prefer the Lasik procedure because of the rapid vision recovery and minimal postoperative care.
Patients with high amounts of nearsightedness should have LASIK. For patients with lower to moderate amounts of myopia, either process may be appropriate, of course, let your refractive surgeon decide what is best for you.
|1. Preferred for lower degree of Myopia & Hyperopia.
|1. Treats high level of Myopia & moderate amount of Hyperopia & Astigmatism.
|2. Slow Visual Recovery.
|2. Visual recovery is faster.
|3. Outcome depends on healing ability of the Patient.
|3. Gives better results with higher predictability, so number of follow-ups are reduced.
|4. Procedure is relatively Painful.
|4. Procedure is Painless.
|5. Laser is given after scraping the epithelium of the Cornea.
|5. Laser is given under the corneal flap. Epithelium remains intact and therefore better visual results.
|6. Eye medications are used for 2-3 months and clear contact lenses are placed on each eye for 3-5 days to prevent infection. The surface layer will begin to regenerate itself and the whole healing process will take up to 3-4 months.
|6. Eye drops used for up to one week and the patient can resume normal activities within three days. Most of the healing process takes place within a week; however, it may take from 1 to 3 months for your vision to fully stabilize.
|7. Pain relief medications required for about 1- 2 days post operatively.
|7. Many LASIK patients experience only 5-6 hours of discomfort.
|8. With PRK there is a small risk of problems arising from an irregular healing response and/or infection. These can generally be treated with medications or in some cases by further surgery.
|8. The disadvantage of LASIK is that it requires an additional surgical step, the creation of the flap. This creation is painless and takes less than a minute to complete. Improper creation of the flap could result in the need for further surgery.
Step by step Operation procedure of LASIK:
In a nutshell, Lasik procedure requires the surgeon to use a surgical instrument called a Microkeratome to create a corneal flap. A portion of the flap remains attached to the eye (as a hinge) while the remainder is gently lifted up and back exposing the inner cornea. The cool beam laser resculpts the cornea and the flap is then returned to its original position.
Step 1: Anesthetic eye-drops are instilled to numb the eye & after that surgeon marks the “Cornea” to guide replacement of the flap.
Step 2: With the help of a specially designed “Suction Ring”, Surgeon holds the eye steady & checks the pressure of the eye.
Step 3: With the help of “Microkeratome”, Surgeon raises a thin layer of Cornea called Corneal Flap, to expose the portion beneath.
Step 4: The flap of around 1/5 of the thickness of Cornea is lifted and reflected to the side.
Step 5: Then as a basic preparation, Surgeon walks the patient through the fixation process & also tests for laser alignment .You will be asked to look at the target light while the Laser is on.
Step 6: The Excimer laser now removes the tissue under the flap. A clicking sound can be heard as each microscopic layer of tissue is vapourized . The process will last from seconds to minutes depending upon the amount of correction required. Ultraviolet light & high-energy pulses from excimer laser reshape the cornea with accuracy up to 0.25 micron.
Step 7: Then, the surgeon lays the flap back into its original position. Healing is rapid and the eye does not require stitches or bandage or contact lens.
Near-Sightedness (Myopia) Correction:
If nearsightedness is being corrected, the excimer Laser is used to remove tissue and reshape the center of the cornea. The amount of tissue removed is dependent upon the degree of near-sightedness that is being corrected.
The excimer laser can be used to treat astigmatism while performing LASIK. Astigmatism measurements describe to what degree the cornea is “non-spherical.” As an example, the surface of a basketball is spherical and would have no astigmatism. The surface of a football, on the other hand, would be highly non-spherical and would have high astigmatism. The excimer laser reduces the degree of astigmatism by removing corneal tissue in an asymmetric manner, utilizing an oval-shaped beam.
Far-Sightedness (Hyperopia) Correction:
If farsightedness (hyperopia) is being corrected, the cornea is flatter than is required given the length of the eye. Hyperopic LASIK is used to reshape the front surface of the eye, making it more curved. In hyperopic (farsighted) treatment, a “donut” of tissue is removed from the mid-periphery of the cornea. This changes the profile of the cornea to steeper the central curvature.
Customized Vision Correction:
Using the same laser, different types of procedures can be performed with varying levels of customization. Special software is used to plan customized treatments uniquely designed for every eye to optimize optical aberrations. The speed of visual recovery and final quality of vision can vary accordingly.
The refractive error is directly programmed into the laser to reshape the cornea and improve vision. Near-sightedness, far-sightedness and astigmatism can be corrected. The natural shape of the cornea is altered which may affect night vision.
Wavefront Optimized LASIK
Software is used to personalize the treatment according to each patient’s eye to retain the natural shape of the cornea more effectively and minimize the affection of night vision that occurs with Classic LASIK.
Small Incision Lenticule Extraction (SMILE) technique
Refractive lenticule extraction is becoming the procedure of choice for the management of myopia and myopic astigmatism owing to its precision, biomechanical stability, and better ocular surface. It has similar safety, efficacy, and predictability as femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and is associated with better patient satisfaction. The conventional technique of small incision lenticule extraction (SMILE) involves docking, femtosecond laser application, lenticule dissection from the surrounding stroma, and extraction.
As SMILE is gaining worldwide acceptance among refractive surgeons, different modifications of the surgical technique have been described to ease the process of lenticule extraction and minimize complications. Good patient selection is essential to ensure optimal patient satisfaction, and novice surgeons should avoid cases with low myopia (thin refractive lenticules), difficult orbital anatomy, high astigmatism, or uncooperative, anxious patients to minimize complications.
Advantages: SMILE has superior ocular surface stability compared to flap-based refractive surgeries. The sub-basal nerve fibre regeneration is faster, and dry eye symptoms, if present, are milder & recover faster. The enhanced ocular surface stability makes SMILE a more feasible option for cases with pre-existing mild dry eyes.
SMILE involves the creation of a small side cut as opposed to a circumferential flap in laser-assisted in situ keratomileusis (LASIK). The biomechanical strength of the cornea is greater in its anterior layer due to stronger intralamellar collagen bonding, and SMILE results in minimal disruption of peripheral collagen fibers resulting in relatively better corneal biomechanics. It is preferred over LASIK in cases with higher refractive errors
The induced higher order aberrations (HOAs) as well as spherical aberrations are less with SMILE. Patients with large pupils are prone to experience glares and halos after LASIK due to increased spherical aberrations, and SMILE may be preferred in such cases.
Absolute contraindications to SMILE-
Relative contraindications to SMILE-
|Pre-existing corneal ectasia (keratoconus, PMD)
|Age ≤ 21 years
|Unstable refractive error
|Mild/treated ocular surface and tear film disorders
|Epithelial and basement membrane corneal dystrophies
|Ocular surface and tear film disorders such as active uncontrolled ocular allergy, severe dry eye, blepharitis
|Pregnancy and breast-feeding
|Controlled diabetes mellitus
|Past ocular herpes infection
|Uncontrolled glaucoma or uveitis
|History of keloid formation
AT A GLANCE-
- The primary advantage of ReLEx SMILE is that the treatment is flapless.
- The retreatment rate after SMILE is low, as the procedure is performed in a closed environment, and is not affected by environmental factors.
Dry eyes feel uncomfortable. If you have dry eyes, your eyes may sting or burn. You may experience dry eyes in certain situations, such as on an airplane, in an air-conditioned room, while riding a bike or after looking at a computer screen for a few hours.
Treatments for dry eyes may make you more comfortable. These treatments can include lifestyle changes and eyedrops. You’ll likely need to take these measures indefinitely to control the symptoms of dry eyes.
Signs and symptoms, which usually affect both eyes, may include:
A stinging, burning or scratchy sensation in your eyes
Stringy mucus in or around your eyes
Sensitivity to light
A sensation of having something in your eyes Difficulty wearing contact lenses
Difficulty with night time driving Watery eyes, which is the body’s response to the irritation of dry eyes
Blurred vision or eye fatigue
Tear glands and tear ducts Open pop-up dialog box
Dry eyes are caused by a variety of reasons that disrupt the healthy tear film. Your tear film has three layers: fatty oils, aqueous fluid and mucus. This combination normally keeps the surface of your eyes lubricated, smooth and clear. Problems with any of these layers can cause dry eyes.
Reasons for tear film dysfunction are many, including hormone changes, autoimmune disease, inflamed eyelid glands or allergic eye disease. For some people, the cause of dry eyes is decreased tear production or increased tear evaporation.
a) Decreased tear production – Dry eyes can occur when you’re unable to produce enough water (aqueous fluid). The medical term for this condition is keratoconjunctivitis sicca, Common causes of decreased tear production include:-
Aging Certain medical conditions including Sjogren’s syndrome, allergic eye disease, rheumatoid arthritis, lupus, scleroderma, graft vs. host disease, sarcoidosis, thyroid disorders or vitamin A deficiency
Certain medications, including antihistamines, decongestants, hormone replacement therapy, antidepressants, and drugs for high blood pressure, acne, birth control and Parkinson’s disease
Corneal nerve desensitivity caused by contact lens use, nerve damage or that caused by laser eye surgery, though symptoms of dry eyes related to this procedure are usually temporary
b) Increased tear evaporation – The oil film produced by small glands on the edge of your eyelids (meibomian glands) might become clogged. Blocked meibomian glands are more common in people with rosacea or other skin disorders.
Common causes of increased tear evaporation include: –
Posterior blepharitis (meibomian gland dysfunction)
Blinking less often, which tends to occur with certain conditions, such as Parkinson’s disease; or when you’re concentrating during certain activities, such as while reading, driving or working at a computer
Eyelid problems, such as the lids turning outward (ectropion) and the lids turning inward (entropion)
Preservatives in topical eyedrops
Wind, smoke or dry air
Vitamin A deficiency
Risk factors – Factors that make it more likely that you’ll experience dry eyes include:
Being older than 50. Tear production tends to diminish as you get older. Dry eyes are more common in people over 50.
Being a woman. A lack of tears is more common in women, especially if they experience hormonal changes due to pregnancy, using birth control pills or menopause.
Eating a diet that is low in vitamin A, which is found in liver, carrots and broccoli, or low in omega-3 fatty acids, which are found in fish, walnuts and vegetable oils.
Wearing contact lenses or having a history of refractive surgery.
People who have dry eyes may experience these complications:
Eye infections. Your tears protect the surface of your eyes from infection. Without adequate tears, you may have an increased risk of eye infection.
Damage to the surface of your eyes. If left untreated, severe dry eyes may lead to eye inflammation, abrasion of the corneal surface, corneal ulcers and vision loss.
Decreased quality of life. Dry eyes can make it difficult to perform everyday activities, such as reading.
Prevention – If you experience dry eyes, pay attention to the situations that are most likely to cause your symptoms. Then find ways to avoid those situations in order to prevent your dry eyes symptoms. For instance:
Avoid air blowing in your eyes. Don’t direct hair dryers, car heaters, air conditioners or fans toward your eyes.
Add moisture to the air. In winter, a humidifier can add moisture to dry indoor air.
Consider wearing wraparound sunglasses or other protective eyewear. Safety shields can be added to the tops and sides of eyeglasses to block wind and dry air. Ask about shields where you buy your eyeglasses.
Take eye breaks during long tasks. If you’re reading or doing another task that requires visual concentration, take periodic eye breaks. Close your eyes for a few minutes. Or blink repeatedly for a few seconds to help spread your tears evenly over your eyes.
Be aware of your environment. The air at high altitudes, in desert areas and in airplanes can be extremely dry. When spending time in such an environment, it may be helpful to frequently close your eyes for a few minutes at a time to minimize evaporation of your tears.
Position your computer screen below eye level. If your computer screen is above eye level, you’ll open your eyes wider to view the screen. Position your computer screen below eye level so that you won’t open your eyes as wide. This may help slow the evaporation of your tears between eye blinks.
Stop smoking and avoid smoke. If you smoke, ask your doctor for help devising a quit-smoking strategy that’s most likely to work for you. If you don’t smoke, stay away from people who do. Smoke can worsen dry eyes symptoms.
Use artificial tears regularly. If you have chronic dry eyes, use eyedrops even when your eyes feel fine to keep them well lubricated.