Tonometry

Tonometry test is a diagnostic test to measure the intraoccular pressure (IOP). When the tonometry test measures the pressure inside the eye, it can help in detecting glaucoma. Ensure that you take off your contact lenses. Do not wear tight clothing around the neck as it can lead to increased pressure inside the eye. Do not smoke a few hours prior to the tonometry test. The tonometry test is also conducted in cases of head or eye surgery and hyphema.

When the pressure builds up within the eye due to improper drainage, it can cause permanent damage to the ooptic nerve. Tonometry is done as part of routine eye examination to check for glaucoma. Anesthetic eye drops are used to numb the eye before using the tonometer. In the application method of testing intraoccular pressure, a paper stained with Fluorescein is placed to the side of the eye thereby staining the front of the eye. The tonometer is then brought close to the cornea for testing. Here the intraoccular pressure is measured by the amount of weight that is needed to flatten the cornea. This type of tonometry test can also be conducted with a pencil-like instrument, which will give instant digital measurement. The air puff method of conducting tonometry is a non-contact one where a puff of air is blown at your eye and change in the light reflected from the cornea is measured to arrive at the intraoccular pressure. This method is preferred for children and persons who have undergone LASIK surgery.

Optic atrophy

Optic atrophy is the result of the fibres of optic nerve failing to transmit the visual information to the brain due to the damaged optic nerve which may result in problems with vision. Optic atrophy refers to the loss or damage of the fibres of the optic nerve. Optic nerve is responsible for carrying images from the eye to the brain. Optic atrophy presents itself with pale appearance of the optic nerve head at the back of the eye; hence this condition is also referred to as optic nerve head pallor. Although optic atrophy affects one eye, bilateral optic atrophy can also occur when the illness damages the nerves of the both eyes.

What causes optic atrophy ?

Optic atrophy is a serious eye disorder that is caused by a underlying disease or condition. Few of the diseases originating in the eye and the nervous system that lead to optic Atrophy are given below.

• Compression of the optic nerve.
  
• Glaucoma or high pressure within the eye.
  
• Infection
  
• Multiple sclerosis
  
• Inflammation of the optic nerve called optic neuritis.
  
• Interruption in blood circulation to the optic nerve in the form of decreased blood supply (ischemia) or oxygen supply (hypoxia).
  
• Tumors on the visual pathway
  
• Trauma
  
• Optic atrophy can even be inherited from parents.
  
• Nutritional deficiencies (especially B12), certain medications and exposure to certain toxins also lead to optic atrophy.
  

Symptoms of optic atrophy

If you face any of these symptoms seek medical attention immediately as any progression of optic atrophy leads to vision loss. Though the occurrence of these symptoms does not necessarily mean optic atrophy, it is always better to rule out this severe eye condition. Ophthalmologist will examine the eyes with an ophthalmoscope and the doctor may recommend few more tests, if he suspects optic atrophy. Tests such as tonometry, pupil light reflex, color vision and visual acuity are conducted.

• Blurred vision
  
• Poor visual function such as low clarity of vision or visual acuity.
  
• Distorted peripheral vision.
  
• Problems in color vision
  
• Decreased brightness in the affected eye. Diminished reaction of the pupil to the light.
  
• Change in the optic disc

Treatment of optic atrophy

Currently there is no sure shot and effective treatment or therapy available for optic atrophy. However ophthalmologist diagnose the underlying condition or disorder that is causing optic atrophy and treat them. This will avoid the further damage of the optic nerve and preserve the existing vision.

Diplopia

Diplopia is one of the serious disorders of the eyes, which is associated with vision impairment. In common terms it is referred to as double vision. The occurrence of diplopia is closely associated with the cranial nerves. The effects caused by this optical disorder restrict normal activities of a person such as reading, walking and driving. The causes associated with diplopia when closely examined are myogenic and neurogenic in origin leading to an optical disruption both of vision and movement of the eyes.

Clinical manifestations and classification

Diplopia can be monocular or binocular in origin. Monocular Diplopia has preexisting-associated conditions such as cataracts, luxation of the lens and keratoconus, which results in light refraction within the eye. Macular degeneration and vitreous damage also causes light refraction retention inside eye causing blurred vision.

Binocular diplopia is caused by neurogenic impairments related to Oculomotor nerve damage, which is an important nerve in facilitating the movement of eye. The muscles associated with the respective functionality are also damaged in this condition. In most cases binocular diplopia is caused because of head injuries leading to cranial damage or traumas caused to the eyes. In some cases aniseikonia (condition which results in difference in the size of images as seen by the person) is also a predominant factor leading to binocular diplopia.

Diplopia occurrence and its respective effects can be further classified as sustained and short-lived forms. Intermittent or short-lived forms are usually a postoperative sequel especially in the case of cataract surgeries. However, diplopia of both continued and short-lived forms predominantly depend upon the thyroid hormone levels and underlying medical conditions such as myasthenia gravis.

Diagnosis of diplopia is a chronological aspect consisting of various factors. A patient complaining of blurred vision has to undergo series of medical and diagnostic investigations to rule out false positive findings. Since diplopia is associated with cranial nerves predominantly the oculomotor nerve, a gaze test is administered by the optometrist to estimate the functionality of nine cardinal vision factors.

This is prior to examining the patient history thoroughly in checking for conditions such as diabetes and hyperthyroidism. Important optometric examinations such as prism test, Bilshowsky test, Stereo acuity test and visual field testing are done to evaluate the impairments existing in the muscles associated with the eye. These tests are carried out after general examinations such as tonometry, fundoscopy and slit lamp examinations.

Treatment

Corrective measures are incorporated to treat the movements of the eye, which is affected drastically in this condition. Refraction errors are analyzed and corrected in order to rectify the blurred vision. Patients are given eye exercises to facilitate proper oculomotor nerve functionalities and also to prevent squint occurrence.