Chủ Nhật, 13 tháng 10, 2013

Presbyopia – Symptoms, Surgery, Correction, Treatment, Causes,Tests

Presbyopia – Symptoms, Surgery, Correction, Treatment, Causes,Tests

What is Presbyopia?


This is the slow and steady loss of the eyes’ ability to actively focus on objects that are nearby – is a clue that an individual has gotten to middle age. It is a very natural, but often annoying portion of becoming older. Presbyopia normally starts being noticeable in the 40s and continues getting worse until around the age of 60.








Individuals might become mindful of this condition when they start needing to hold books or magazines at arm’s length in order to read. If an individual is nearsighted, they might temporarily be able to manage presbyopia by reading without glasses.


A simple exam of the eyes will confirm presbyopia. It can be corrected with reading glasses that are nonprescription or prescription or contact lenses. Surgery is also another option.


Presbyopia Symptoms


Presbyopia normally gradually develops, over years. Individuals may first recognize these symptoms and signs:



  • Blurred vision at normal distance for reading

  • Inclination to hold reading resources further away in order to make the printed material clearer

  • Headaches or eyestrain after close work or reading


If an individual is having problems with close work or difficulties reading, or if close up vision is blurry and stopping an individual from enjoying activities which are normal, see the eye doctor. She or he can decide whether an individual has presbyopia and recommend options.


Presbyopia Causes


Presbyopia occurs because the lens of the eyes become hardened, which happens with age. As the lens start to become less supple, it may no more be able to adjust shapes and images that are close-up appear unfocused.


To permit the processing of an image, the eyes count on the lens as well as the cornea to focus the reflected light from the items. The cornea is the front surface that is clear and dome-shaped. The lens is a structure that is clear and about the shape and the size of an M&M candy. Both structures bend – reflecting the light that is entering the eye – focusing the image onto the retina that is situated on the wall in back of the eye.


Unlike the cornea, the lens are to some extent flexible and are able to change their contour with the aid of a muscle which is circular and surrounds the lens. When the individual looks at anything far away, this muscle relaxes. But when the individual looks at anything close by, the muscle tightens, allowing the supple lens to curve steeply and adjust its focus. Age is the biggest risk for presbyopia. Just about everyone will experience this after age 40.


Premature presbyopia


But, certain individuals may develop presbyopia prior than age 40 because of certain drugs or certain diseases. This early presbyopia may be a sign that there is a general disease that the individual might not be mindful of. Risk factors for early presbyopia consists of:


Drugs
Some prescription and non-prescription drugs may affect the lens flexibility. They can include antihistamines, antidepressants, alcohol and diuretics.


Systemic diseases
Several diseases, for instance diabetes, cardiovascular diseases, multiple sclerosis may escalate the risk of premature presbyopia.


Presbyopia Treatment


Whenever an individual has a problem with vision, they need to schedule a visit with the eye specialist as quickly as possible. When vision is blurred it can suggest a need of prescription modification or an added serious problem with the eyes that can need immediately treated.


Presbyopia is normally diagnosed with a regular eye exam, managed by an optometrist or ophthalmologist. A complete exam of the eye includes a succession of tests. The eye physician will likely administer drops in the eye to dilate or widen the pupils, making the eyes more sensitive to light for several hours after the exam. This dilation lets the physician more easily examine the inside as well as the back of the eye.
The doctor will use several instruments, aim lights that are bright at the eye and ask that the individual look thru an assortment of lenses in order to test the close-up and distant vision. Every test will allow the doctor to evaluate different aspects of vision.



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It is advised that everyone have a complete eye exam:



  • Between the ages of 20 and 29 – once

  • Between the ages of 30 and 39 – twice

  • Between the ages 40 and 64 – every 3 to 4 years

  • Starting at age 65 – every 1 to 2 years


The physician can recommend more frequent exams, dependent on the finding of early exams. For instance, if an individual wears contacts or glasses, the eyes might need to be checked more often.


Treatment options can include corrective lenses, refractive surgery or lens implants.


Corrective lenses
When the individual has good vision that needs no correction before developing presbyopia, they might be able to use nonprescription over-the-counter reading glasses.


You will need prescription glasses for presbyopia if over the counter glasses are not adequate or if you already need prescription lenses for farsightedness, nearsightedness or astigmatism. The option choices include:



  • Prescription reading glasses

  • Bifocals : These glasses correct both distance as well as reading prescriptions

  • Trifocals : These glasses have corrections for close work, middle vision – such as for computer screens – and distant vision.

  • Bifocal contact lenses : Like bifocal glasses these contact lenses provide both close up correction as well as distance on each contact. The bottom part of the lens – reading portion – is weighted to keep the lens correctly positioned on the eye.

  • Monovision contact lenses : The contact lenses are for distant vision in the dominant eye and a contact lens for close vision in the eye that is non-dominant.

  • Modified Monovision : This involves wearing a bifocal contact lens in the nondominant eye and a contact lens for distance in the dominant eye. One eye is used for reading and both eyes for distance.


Refractive surgery


This surgery alternates the shape of the cornea. This surgery is equivalent to wearing monovision contact lenses. This is used to improve close-up vision in the nondominant eye. It is recommended that individuals try monovision contacts first in order to determine if this the individual can adjust to this kind of correction before deciding on the refractive surgery.


Refractive surgery procedures include:


Conductive keratoplasty or CK
This uses radiofrequency energy to apply heat to very tiny spots around the cornea. The unit of change in the cornea’s curvature depends on the number and spacing of the spots. The results of CK are varied and unstable in most individuals.


Laser-assisted in-situ keratomileusis or LASIK
This procedure is done using a special laser or an instrument called a keratome to make a very thin, hinged flap in the cornea. Then an excimer laser is used to remove inner layers of the cornea to steepen its domed shape.


Laser epithelial keratomileusis or LASEK
With this procedure, rather than creating a flap in the cornea, the surgeon creates a flap in the cornea’s thin protecting cover or epithelium. The excimer laser to reshape the cornea’s outer layers and steepen its curvature as well as then reposition the epithelial flap.


Photorefractive keratectomy or PRK
This is similar to LASEK, except the surgeon removes the epithelium. When it grows back naturally, it will conform to the cornea’s new shape.


Lens Implants


This procedure involves removal of the clear natural lens and replacing them with a synthetic lens inside the eye.













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