Nearsightedness is also called “myopia”. Victims with myopia have elongated eyeballs. Due to their elongated eyes, the light falls in front of the retina instead of on the photoreceptors. This causes them to see things that are nearer to them, thus “nearsighted”. There are two ways to treat nearsightedness: wearing concave lenses, and laser eye surgery. Concave lenses diverge the light going into the eye so that the image falls right on the retina. Laser eye surgery uses a laser to cut and reshape the cornea of the victim.
After the surgery the person’s cornea will be able to focus light into the retina properly. Example of an eyeball with myopia Symptoms: Blurred vision Being able to see objects nearby but have difficulty seeing objects further away. Farsightedness is also known as hyperopia. Hyperopia is when the victims have a short eye, so it’s the complete opposite of myopia. The victims of hyperopia cannot see objects that are nearby because their short eyeballs cause the light rays focus behind the retina. Hyperopia can be fixed with convex lenses.
Convex lenses help focus the light so that it falls right on the retina. Laser eye surgery can also be performed, but once the operation is finished you will need glasses or contacts to see objects that are farther in range. Example of an eyeball with hyperopia Symptoms: Eyes feel tired or strained. Headaches, squinting and blurred vision when viewing objects that are near. Presbyopia Presbyopia is when a person’s lens loses the ability to focus on objects. The loss of power of the ciliary muscle has also been known to be the cause.
This low elasticity of the lens makes it hard to focus on objects up close. Presbyopia is a part of aging and can affect anyone. Victims usually notice presbyopia at around age 45. Presbyopia cannot be cured but can be corrected with contact lenses or glasses. Some victims have been known to use “mono-vision,” which means one eye is corrected for nearsightedness and the other for farsightedness. Example of an eyeball with presbyopia Symptoms: Difficulty reading things in normal/fine print. Problem seeing nearby objects. Having eye strain even under normal conditions. Astigmatism
Astigmatism is an inherited condition that causes an uneven curvature in a person’s cornea. This uneven curvature causes the cornea to be asymmetrical thus not being able to bend light properly and as a result have blurred vision. Astigmatism doesn’t have a cure but can be corrected with glasses and contacts which help focus the light on the retina. Laser eye surgery is also an alternative, fixing the surface of the cornea to allow proper bending of the light. Example of an eyeball with astigmatism Symptoms: Most of the symptoms are similar to myopia and myopia Blurred vision at near and far ranges.
Eyestrain and headaches Cataracts Cataracts can develop as the individual ages. The protein structures in the lens start to degenerate making the lens itself opaque (not transparent) and prevents light from passing through. Cataracts can cause white-grey spots on the lens. Cataracts can be slowed down by wearing ultraviolet sunglasses. Once cataract has fully developed a surgical procedure can be done to replace the lens. Example of an eyeball with cataracts Symptoms: Vision may become blurred or hazy due to the white /grey spots Colours might start to fade as well.
Glaucoma Glaucoma is an eye disease in which the optic nerve is damaged causing permanent damage to the victim’s vision and can lead to blindness if untreated. Glaucoma is often the result of increased fluid pressure in the aqueous humour. An example could be a ruptured blood vessel, which would then cause increased fluid pressure in the aqueous humour. Glaucoma causes the loss of ganglion cells. There are several types of glaucoma, such types are: open angle glaucoma, angle closure glaucoma, congenital glaucoma, and secondary glaucoma.
Treatment depends on the type of glaucoma you have, but most common treatment is reduction of pressure in the eye. This can be achieved by pills, laser therapy, and eye surgery. Example of an eyeball with glaucoma . Symptoms: The most common symptom is the increase of pressure in your eye Macular Degeneration (AMD) Macular degeneration is the main cause of blindness in adults over the age of 50. It occurs in two forms, Dry and Wet. Macular degeneration is the loss of vision in the macula or the center of visual field. This causes difficulty reading and recognizing faces.
However, since only the macula is damaged peripheral vision isn’t impaired. Dry AMD is caused by drusen accumulating between the choroid and retina, this can causes the retina to detach. Wet AMD is when blood vessels from the choroid grow into and behind the retina, which can eventually cause the retina to detach. Treatments vary on the type of AMD. For wet AMD laser coagulation can help reduce the growth of the blood vessels. Example of an eyeball with AMD Synonyms: Dry: Blurred Vision within the Central Visual Field Wet: Inability to focus on a certain spot on a grid Colour Blindness.
Colour blindness, or rather colour deficiency is the inability to see certain colours, and/or inability to distinguish between them. This is caused by the lack of specific cones. Most cases it’s the red and green cones that are absent, causing inability to distinguish between the two colours. Males are more likely to be colour blind because the genes that produce the photo pigments are carried on the X-chromosomes of males. If these genes are damaged or absent it results in colour blindness, or rather colour deficiency. Colour “blindness” can also occur when the eye is damaged due to chemicals, to the optic nerve and the brain.
As far as diagnoses goes please look at the picture below. The number 74 should appear if the individual has normal vision. Symptom: If you cannot see the green 74 then you’re colour blind Sensory Defects Assignment Part 2 a. Hearing Defects and their Correction: Conductive hearing loss Conductive hearing loss is when sound waves aren’t conducted properly; this may occur in the outer ear, tympanic membrane (Eardrum), the middle ear and inner ear. The Weber test is used to check if the patient has this condition. The common causes of this hearing loss are earwax and ear infections.
Depending on which section of the ear is affected the causes are different. Outer Ear: Ear Wax and Ear Infections Treatment: Auditory canal cleaned, and antibiotics for the ear infections. Tympanic Membrane: Tympanic perforation (hole in the eardrum) and refraction (the eardrum is located deeper in the auditory canal than usual), and membrane tensions caused by pressure. Treatment: More complicated surgical procedures can be done to fix or replace the perforated ear drum. Middle Ear: Fluid Accumulation and Eustachian Tube Blockage; which in turn causes pressure Thus making it for the ossicles to vibrate, or conduct vibrations.
Treatment: Fluid accumulation can often be fixed by putting a small hole in the tympanic membrane to drain the fluid. Surgical procedures can be done to remove the blockage of the Eustachian tube. Inner Ear: Severe Otosclerosis, which is the blocking of the oval and round window. Treatment: Surgical procedures can be undertaken to remove the blockage at the oval and round window. Example of Fluid Accumulation: Symptoms: Certain sounds may be louder than others Difficulty hearing in a noisy environment High-pitched sounds “s” and “th” are hard to hear Sensory Hearing Loss.
Sensory Hearing loss is caused by the destruction of the hair cells located inside the organ of Corti; this is the more common type. The destruction of hair cells is caused by prolonged exposure to loud noises, (over 80dB). Destruction of the hair cells can cause permanent hearing loss, and depending on which hair cells are destroyed, determines which frequency you are still able to hear. There are rare types of sensory hearing loss where the vestibulocochlear nerve, or parts of the brain associated with auditory reception is damaged. The Weber and Rhine test can be used to check if the patient has sensory hearing loss.
Stem cells and gene therapy can help the re-growth of these hair cells. Hearing Aids are a popular choice for most patients to regain their hearing. Hearing Aids Hearing aids help to amplify the sound waves entering the ear, although the hearing aids helps improves auditory reception, nothing can be done to regain normal hearing. Hearing aids do not work for patients who are deaf or severely hard of hearing. Symptoms: There aren’t really tell-tale signs for the need of hearing aids specifically, any symptoms of hearing loss is a sign. Cochlear implants.
Cochlear implants are often referred to as bionic ears because they provide patients with the sense of sound. Electrical stimulation is used to create a sense of hearing. The quality of the sound isn’t comparable to patients with normal ears, but does enable the patients to hear and interpret speech. This is due to the brain receiving and processing less sound information. Cochlear implants are different from hearing aids because they have to be surgically implanted and is used on profoundly deaf patients. Symptoms: Any symptoms of hearing loss are a sign you need cochlear implants. Tinnitus.
Tinnitus is not a disease or a condition, but rather a symptom for other problems like age related hearing loss, sensory hearing loss, or congenital hearing loss. Tinnitus is the ringing in the ears. Tinnitus often worsens with age, treatment can help reduce the tinnitus making it less noticeable. Tinnitus can be prevented by staying away from loud noises such as concerts or constant usage of in-ear headphones. Gamma knife radiosurgery can help reduce tinnitus, and drugs such as melatonin have known to help as well. The Draper Laboratory has created a device that helps patients with Tinnitus.
Here’s a link to the fascinating article http://www. scientificamerican. com/article. cfm? id=tinnitus-treatment Symptoms: Ringing in the ear and excess unidentifiable sounds in the ear. b. Equilibrium Defects and their Correction: Vertigo Patients with vertigo experience dizziness. The patients often have a perception of motion, this causes balance disorders that make it difficult to stand or walk. The problem can be located at the vestibular system in the inner ear. There are three types of vertigo; objective, subjective, and pseudovertigo.
Objective is when the patients undergo a sensation where the objects around them are moving; while subjective refers to the individual themselves feel as if they are moving. Pseudovertigo is when a patient has “intensive sensation of rotation” in their head. Concussions and vestibular migraines can cause a sensation of vertigo. Benign paroxysmal positional vertigo or (BPPV) is the most common type of vestibular disorder and is caused when the calcium carbonate inside the ear breaks loose of the otoconial membrane and enters the semicircular canal.
This causes a sensation of movement/motion. Treatment depends on the type of vertigo a patient is diagnosed with. Symptoms: Dizziness, head-aches, and migraines can sometimes be a tell-tale sign you have vertigo. Labyrinthitis Labyrinthitis is when parts of the inner ear become inflamed and or irritated causing interference with one’s hearing and balance. Smoking and large consumption of alcohol can increase your risks of getting Labyrinthitis. Symptoms can include dizziness, (vertigo), ringing in the ear (tinnitus), loss of hearing in one ear, and loss of balance.
An MRI machine can be used to test if an individual has Labyrinthitis. Labyrinthitis goes away after a couple of weeks however treatment can be taken to reduce the symptoms. meclizine or scopolamine help reduce the sensation of dizziness.
Symptoms: Severe Vertigo and vomiting This is an MRI of a patient with Labrynthitis References Google. com Google Images www. eyeglassguide. com www. wikipedia. org www. asha. org/public/hearing/conductive-hearing-loss/Share.