Chapter 29: Introduction to the lens, cataracts and surgery
Introduction
The human eye is one of the most complex organisms in the human body and the lens is one of the most impressive structures within it! Despite being slightly over two centimeters in diameter, the human eye has over two million moving parts. Sight is a rapidly occurring process that involves continuous interaction between the eye, the nervous system, and the brain. The lens is a key component of the eye which, coupled with the cornea, focuses images onto the retina. This is easily achieved by the lenses biconvex shape, refractive index, clarity, and youth. In our younger years we have the ability to bring near objects into focus by the act of accommodation. Ciliary muscle shortening allows the lens to take on a more curved shape. Human vision can be limited by the optical quality of the eye, especially by the presence of a cataract. Cataracts are a very common age-related visual problem and the number of cataract operations performed is continuously on the rise; approximately 20 million surgeries were performed in 2010.
The Lens
The crystalline lens is a double-convex, avascular, transparent membrane-like structure enclosed by a capsule, which is quite malleable, a feature that keeps it under continual tension. As a result of this tension, the lens naturally has an annular contour. The lens is located in the front part of the eye behind the iris and in front of the vitreous body. The lens is held in position by slender suspensory ligaments, also known as zonules. The zonules attach at the equator of the lens like springs and attach the lens to the surrounding ciliary body.
The primary function of the crystalline lens is to focus the incoming light...
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...ter the treatment is completed you will notice a gradual improvement in your vision within a few days. It is very normal to see a few floaters in your vision after the treatment. Upon completion of the treatment the physician will schedule a follow-up visit within one to two weeks post laser.
After treatment, patients should contact their doctors’ office immediately if they notice or experience the following:
• Pain, redness, or irritation in the surgical eye
• An increase in floaters
• Flashing lights in their vision
• A black shadow/curtain in their vision they can’t see through
Managing Non-routine Cataract Surgery
Cataract surgery may be the most commonly performed procedure around the world, but not every case is routine; many patients present with retinal or corneal conditions that require surgeons to take extra precautions before, during and after surgery.
Optometrists have accepted vision therapy, which is a medical treatment for optical muscle disabilities, as a feasible treatment used for eye related problems; claiming the treatment can strengthen vision and give the patient the opportunity to understand visuals quicker and clearer (Press). Vision therapy originated in the 1950s and over the past 25 years, has gained popularity, mainly because of new technological innovations in the field of treatment. Generally, vision therapy is prescribed as a measure mainly for people between the ages of 3 and 18. With the results from a comprehensive series of eye tests, the optometrist can work with the patient using special instruments—prisms, filters, occluders, and eye lenses—and strengthen the eye muscles, thus improving sight. According to optometrists in favor of vision therapy, these methods of treatment using these instruments function as safer routes to repair eye disabilities. Although vision therapy can yield favorable results, the practice as a treatment for innate eye disabilities has been in hot debate lately; as it can exceed $8000 and insurance companies do not cover the treatment. For decades, insurance companies have refused to accept vision therapy as a legitimate method for repairing eyesight (Boink). Concomitant with lack of insurance, the cost for a full treatment can exceed $8000, and doctors cannot guarantee a successful outcome. Recently, parents of children with eye related disabilities, such as amblyopia (lazy eye) and strabismus (cross-eye), and doctors have attempted to cooperate with public schools to allow families access to school-funded doctors to practice vision therapy. With a tight budget, most schools cannot afford to supply vision therapy, and a...
Glaucoma is a disease of the eye and it is fluid pressure within the eye rises and if the eye is left untreated the patient might lose vision or maybe even blind. But this disease is generally affects both eyes but although one of their eyes may have more severe signs or symptoms then the other eye. When you have glaucoma there are small spaces in the front of the eye and they are called anterior chamber. There is clear liquid that flows in and out of the anterior chamber and the fluid nourishes and bathes nearby the tissues. And if the patient has glaucoma the fluid dose not drain like it should drain but the fluid drains out of the eye. And this may lead to fluid build up and pressure inside the rises of the eye. Unless the pressure is brought down and controlled and the optic nerves and some of the other parts of the eye might become damaged leading to ...
Until recently, those affected were left without hope of a cure or even a treatment that would somewhat improve their vision. But over the last few years, several groups of scientists have been working on a partial cure in the form of neuroprostheses, artificial devices which are inserted into the eye behind or on top of the damaged retinal area. These photoreceptive chips, in theory, should provide information to the healthy neurons residing in the retina, substituting for the damaged photoreceptors. When we open our eyes, millions of tiny events occur that allow us to see. Our pupils automatically constrict in accordance to the light level, the variable lens bends and adjusts to fit the distance of what we are looking at, and our photoreceptors receive information in accordance to the previous factors.
In 1802, philosopher William Paley called the eye a miracle of "design". Your eyes are responsible for 80 percent of all of the information that your brain receives. (Schleifer, 2014) But how did our eyes form? How are we able to see what we see? What allows us to see the colors we see? The eye is made up of many different complex parts that all work together to create images our brain can understand. The eye is made up of the front parts, or parts we can see, the interior parts, or parts we can’t see, the nerves which carry signals to our brain, and glands that protect our eyes. The eyes we have today have evolved over a long period of time and undergone many different changes, according to Charles Darwin, Richard Dawkins, and many other evolutionists. When all of the different parts of our eyes work together we are able to see a clear image that is produced from our brain.
...atment option your doctor suggests, careful monitoring and follow-up visits are required to successfully combat the symptoms.
A laser may be the only treatment needed if only one area has been detached and it is small. Surgery. This may be done if the area that has been detached is large. During the surgery, fluid will be drained and a freezing probe will be used to create scar tissue. The scar tissue will help the retina adhere to its underlying tissues once it flattens out.
The five senses include sight, smell, touch, taste, and hearing. Sight is the power of seeing objects and people. To see we use our eyes, our eye is a sphere with a diameter of about 2.5 cm or 1 inch. Our eyes include the eyebrows, eyelids, conjunctiva, lacrimal apparatus, and extrinsic eye muscles. The eyelids are thin, skin covered folds supported by the connective tissue sheets called tarsal plates and are separated by the palpebral fissure and meet at medial and lateral angles of the eye. The eyelid muscle cause blinking every 3-7 seconds and when the objects get in your eye, the flexibility is activated to protect the eye. The eyelashes also protect the eye. Anything that touches the eyelashes is blown away because it will cause your eye to blink. The conjunctiva in our eyes is a mucous membrane; it helps to line the eyelids. The function of the conjunctiva is to produce a lubricating mucus that prevents the eyes from drying out. A conjunctival sac is where contact lens lies and occurs when the eyes are closed and a slit like space occurs. An inflammation of the conjunctiva is called conjunctivitis and happens when the eye get red and really irritated. The lacrimal apparatus in our eyes drains the lacrimal secretions into the nasal cavity. The lacrimal fluid in the eye cleans and protects eye as it moistens. The fluid contains mucous, antibodies, and lysosome. The extrinsic eye muscles originate and insert into outer surface of the eyeball. The extrinsic eye muscles allow the eye to follow a moving object and provide wires to maintain shape of eyeball and hold it in orbit. When movements of these muscles are not the same, a person cannot focus on images correctly and see two images instead. The eye is called an eyeball and ha...
My interest into becoming an optometrist had begun when I was in high school; it happened in an unconventional way. It was not through watching videos, or someone explaining to me what optometry was, but rather, seeing the power of it firsthand. There was a point in my life where I felt emotions that I was unable to comprehend at the time. Seeing a family member on an operating table was the most petrifying moment that I have gone through, especially when the person on the table was my father. My father had to get a chalazion removed from his right eyelid. The doctor told my family that my father would be susceptible to certain health risks because of his diabetes and the severity of his cyst. This procedure was the hardest thing I have had to deal with in my life because it made me feel helpless. Usually, when my dad needs help he always asks me, but this time I could not do anything. It is interesting to think that something so small had such a big affect on my life.
The four main components of the eye that are responsible for producing an image are the cornea, lens, ciliary muscles and retina. Incoming light rays first encounter the cornea. The bulging shape of the cornea causes it to refract light similar to a convex lens. Because of the great difference in optical density between the air and the corneal material and because of the shape of the cornea, most of the refraction to incoming light rays takes place here. Light rays then pass through the pupil, and then onto the lens. A small amount of additional refraction takes place here as the light rays are "fine tuned" so that they focus on the retina.
This advanced planning lets your doctor take his or her time when making difficult decisions instead of having to hurriedly make all of them in the middle of your procedure. Also, instead of using a scalpel to make incisions, a super-precise laser beam is used. This means that every incision made is extremely thin, which can lead to faster healing and a decreased likelihood of surgery complications. While basic cataract surgery can have a good outcome when performed by a skilled and experienced surgeon, laser cataract surgery with 3D imaging is virtually error-proof and easier for any doctor to perform. 2.
LASIK eye surgery, also called, laser-assisted in-situ kerkatolmileusis, is a procedure which corrects vision problems and eliminates the need for glasses or contact lenses. It’s a type of eye surgery that changes the shape of the cornea using a laser. With LASIK eye surgery, the main goal is to “bend light rays to focus more precisely on the patient’s retina” and to produce clearer and sharper vision.
It is estimated that about 1.3 million people in the U.S. are legally blind. Legal blindness refers to central visual acuity of 20/200 or less in the better eye with the best possible correction, or a visual field of 20 degrees or less (Gretchyn 1). African-Americans and Hispanics are at higher risks for blindness and vision impairment than Caucasians because they are at higher risk for developing diabetes, diabetic retinopathy, and glaucoma (Gardner 2) . There are aids for hearing disabilities and physical disabilities but what about aids for visual disabilities?Visual Impairment aids can protect the visually impaired from danger, mistreatment, and dependence.
According to Mayoclinic.org the definition of cataract is a clouding of the normally clear lens of your eye (July 2013). I would like to discuss with you the pathophysiology of this disorder, the causes of this issue as well as some of the effects it can have on you, and some treatment options for those you suffer from this internal eye disorder. A cataract affects the lens of the eye. The lens is generally clear in color, and it is elastic in nature. The lens is surrounded by a capsule like case and sits behind the iris inside the eye (“Cataracts” Linton 2012). When the lens of the eye becomes cloudy, blurred, or there seems to be a more dim vision which replaces the normal transparency, this is called a cataract (“Cataracts” Linton 2012).
Have you ever wondered why the sky is blue. Often times I find myself looking up on a clear day, pondering over that question? Why isn’t it green, or red or pink for even that matter. Every day, the human eye blinks more than 23,00 times. The human eye is a complicated organ that performs one of the most important tasks for our body. There are many questions about the eye however. What function do they perform? What happens if we don’t take care of them? How exactly do they work together to help us form images? Exactly how far can they human eye see?
This protects the eye from becoming dry.The Cornea, a part of the sclera, is the transparent window of the eye through which light passes. The focusing of the light begins in the cornea.Behind the Cornea is a watery fluid called the aqueous humor. This fluid fills a curved, crescent shaped space, thick in the center and thinner toward the edges. The cornea and the aqueous humor together make an outer lens that refracts, or bends, light and dire...