Periphery Vision

Periphery Vision

A person's peripheral vision is what that person sees on the sides without directly looking to the side. In order to measure peripheral vision loss, a person should be looking straight ahead. If think your peripheral vision is blurry it is important to see an eye doctor as soon as possible. A disease called glaucoma causes peripheral vision loss. A doctor will use one of two tests to measure the periphery vision of a patient. These are called visual field tests. The visual field of a patient includes their central vision and the vision in their periphery.The first visual field test is called a confrontational visual field. This is done with a doctor and patient face to face across from each other. The patient covers one eye and looks at the doctor's nose. The doctor then holds up fingers on either side of the patient. While looking directly at the doctor, the patient is asked how many fingers are being held up. If the patient does not answer correctly then there is more of a concern for peripheral vision loss. The second test for peripheral vision is a more formal test called an automated visual field test. The most popular automated visual field test done in many doctor's offices is the Humphrey visual field test. The test takes about 5–8 minutes per eyeThe patient places their chin into a bowl type machine and is asked to look straight ahead. The test is most accurate when the patient can maintain fixation on the central target. The patient is then given a hand held buzzer to press when they see a light is their peripheral vision. One eye is tested at a time, usually right then left. The eye that is not being tested is covered with an eye patch. When taking the visual field test, be sure to blink normally and concentrate on doing the test accurately. If the test shows that the patient was not looking straight ahead for the test, it could affect the accuracy of results. Your doctor may ask you to repeat the test if they feel that the results are not reliable. Glaucoma is a disease of the optic nerve. When a patient has glaucoma their peripheral vision is at risk. Most patients with glaucoma do not even know that they have it. Peripheral vision loss in glaucoma tends to happen very slowly. There are usually no obvious signs or symptoms. It is best to see an ophthalmologist at regular intervals especially if you have risk factors for glaucoma. One big risk factor for glaucoma is race. Populations that are more at risk for glaucoma include persons of African American ancestery, Hispanics, and Asians. If someone in your family has glaucoma, you are also at higher risk for glaucoma. Having certain other diseases can also put you at risk for glaucoma. For example, patients who have sleep apnea are at higher risk for developing glaucoma. The peripheral vision loss that occurs in glaucoma is permanent and irreversible. It is extremely important to see your eye doctor to determine if you have glaucoma. Glaucome is not curable. But, glaucoma is very treatable. there are several medications that exist to treat glaucoma and most of these medications are well tolerated by most people.Testing of your periphery vision involves a visual field test. This can be done by a confrontational visual field or a more formal automated visual field. These tests are non invasive (no needles!) and take a few minutes per eye. Testing peripheral vision is especially important if you have risk factors for glaucoma. Glaucoma is a treatable but not curable eye disease. If it is untreated it can result in permanent peripheral vision loss. Glaucoma can also lead to total blindness and is one of the leading causes of vision loss in the world. Sources:Khoury, Johnny, M.; Donahue, Sean, P.; Lavin, Patric, J.; Tsai, James (1999). "Comparison of 24-2 and 30-2 Perimetry in Glaucomatous and Nonglaucomatous Optic Neuropathies".Journal of Neuro-Ophthalmology.19(2): 100–108.doi:10.1097/00041327-199906000-00004.PMID10380130Ishiyama, Y.; Murata, H.; Mayama, C.; Asaoka, R. (11 November 2014)."An Objective Evaluation of Gaze Tracking in Humphrey Perimetry and the Relation With the Reproducibility of Visual Fields: A Pilot Study in Glaucoma".Investigative Ophthalmology & Visual Science.55(12): 8149–8152.doi:10.1167/iovs.14-15541.PMID25389198McMonnies CW. Glaucoma history and risk factors. J Optom. 2017 Apr-Jun;10(2):71-78. doi: 10.1016/j.optom.2016.02.003. Epub 2016 Mar 23. PMID: 27025415; PMCID: PMC5383456.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5383456/
4 min read
Glaucoma Narrow Angle

Narrow Angle Glaucoma

Glaucoma damages your optic nerve, which normally sends signals to your brain so you can see. Glaucoma is the leading cause of irreversible blindness. Glaucoma comes in many varieties. One serious but rare type of glaucoma is Narrow Angle Glaucoma which sometimes is also called Angle Closure Glaucoma. Narrow angle glaucoma is different from the most common form of glaucoma, known as open angle glaucoma. While open-angle glaucoma unfolds over years, narrow angle glaucoma can be acute, where it happens suddenly, or it can also be chronic, where it happens over a longer time.  The difference between narrow angle glaucoma and open angle glaucoma is the way in which a person's eye is shaped.Everything that happens in narrow-angle glaucoma can be understood by understanding the name. Your eye's "angle" rests between the eye's natural drainage system, known as the trabecular meshwork, and the iris. Narrowing or closure of this angle results in a clogging of the drainage system. As a result, fluid pressure builds up in the eye. This rapidly alters one's vision and can progress to blindness within a day.Symptoms of acute narrow-angle glaucoma include sudden eye pain, red eye, blurry vision, rainbows, nausea, vomiting, and headaches. This is a medical emergency that could result in permanent vision loss if not treated quickly. If you have these symptoms, you should see an eye doctor immediately, or go to an emergency room where you can get medications to lower your eye pressure.Chronic narrow angle glaucoma occurs over time. It does not usually present with the above sudden symptoms. Instead, it presents asymptomatically on routine exam. The doctor may see tissue adhesions (known as synechiae) formed between your iris and trabecular meshwork. They may also note an increasing eye fluid pressure (known as "intraocular pressure," or IOP). If you have the above symptoms, your eye doctor will want examine you further. They will first want to take a look into the front part of your eye to visualize your eye drainage angle. This is done with an instrument called a gonioscope. The angle of the eye is the part of the eye that drains the fluid from the eye. When the angle is narrow, you have an anatomically narrow angle. This shape of the drainage system can then lead to narrow angle glaucoma.Some people just have an anatomically narrow angle. Other people may develop one over time or due to trauma. With age, the lens within our eyes enlarges, and this can push up on the iris, which narrows the angle. Physical injury to the eye can also dislocate the lens, causing narrow-angle glaucoma. Some patients are born with anatomic differences that decrease their eye angle. Patients at risk for narrow angle glaucoma include those with smaller eyes (resulting in far-sightedness), older age, female sex, Asian and Native American ethnicity, or having a family history of angle-closure. Chronic narrow-angle glaucoma may occur over time in patients when tissue adhesions form between the iris and trabecular meshwork. The eye doctor will do a gonioscopy exam, in which they place a large lens onto your eye to take a direct look at the angle of your eye. Your doctor will also peer through a slit-lamp microscope to look at the entire front part of your eye. They will use a ophthalmoscope to look at your optic nerve to see if there is damage. Doctors may also check how good your peripheral vision is through a testing of your visual fields. They can also in office scan, called an OCT, or an ultrasound (UBM) of your eye to look at your optic nerve or eye angle. In healthy eyes, IOP is 10-21 mm Hg. Glaucoma is defined by elevated IOP. Acute narrow-angle glaucoma usually presents with a sudden increase in IOP >40 mm Hg due to the obstruction of the drainage angle. As mentioned above, such increased pressure in the eye may damage the optic nerve. Medical treatment for acute narrow-angle glaucoma should first quickly lower your fluid pressure levels (IOP) to prevent further damage to the optic nerve. Your doctor can use topical eye drops including various classes of beta blockers, selective alpha agonists, carbonic anhydrase inhibitors,  amongst others. They may also use systemic therapy like mannitol or oral osmotic agents.The next step in the treatment of narrow-angle glaucoma, both acute and chronic, is a laser iridotomy. An eye surgeon will use a laser to make a small pinhole in your iris. Fluid flows through this hole and fixes the drainage problem. If you have a narrow angle in one eye, your other eye is also at risk. Your surgeon will perform the same procedure in the other eye as well to prevent future attacks. Your IOP will be routinely monitored as an extra method of prevention.


Sources: 
https://glaucoma.org/are-you-an-angle-closure-glaucoma-suspect/https://glaucoma.org/what-is-angle-closure-glaucoma/?print=printhttps://eyewiki.aao.org/Primary_vs._Secondary_Angle_Closure_Glaucomahttps://www.aao.org/munnerlyn-laser-surgery-center/angleclosure-glaucoma-19https://www.aoa.org/healthy-eyes/eye-and-vision-conditions/glaucoma?sso=y 
5 min read
Glaucoma Open Angle

Glaucoma Open Angle

Glaucoma that has an open angle, more commonly referred to as Open Angle Glaucoma, is the most common type of glaucoma. Primary Open Angle Glaucoma, abbreviated POAG, affects around 68 million people in the world! The following people are at greater risk for this type of glaucoma: Older individuals, Blacks, African-American, Hispanics, and people who have a history of sleep apnea (1-3). The first step in treating Open Angle Glaucoma is either eye drops or SLT laser by an ophthalmologist.Glaucoma is a disease of the optic nerve. The optic nerve is a cranial nerve that connects your brain to your eye, and allows you to see. While glaucoma is affected by high pressure in the eye, there are also types of glaucoma in which the eye pressure is normal. It is important to note that eye pressure is not necessarily related to blood pressure. Patients often think that if they have high blood pressure, they will have high eye pressure. This is not true. There are many different types of glaucoma but two of the broad categories of glaucoma include open angle glaucoma and closed angle, or narrow angle, glaucoma. These two terms refer to the shape and configuration of the drainage system of the eye. The drainage system of the eye is found in the anatomic angle of the eye, hence the names “open angle” and “narrow angle.” When a patient has open angle glaucoma, their eye pressure is high despite the drainage system being anatomically “open.” When someone has narrow angle glaucoma, it is the shape and configuration of the drainage system, or angle, that is contributing to the patient having high pressure in the eye.The eye is a dynamic structure that is filled with fluid called aqueous. This fluid is constantly being cycled in and out of the eye through the angle of the eye. In open angle glaucoma, the “back-up” of fluid typically happens in the small microscopic structures that are beyond the angle. In narrow angle, the shape of the drainage system itself is contributing to high pressures. There is also an entity called normotensive glaucoma in which the eye pressure is not particularly high, but damage to the optic nerve is still happening. In order to figure out what type of glaucoma you have, your doctor will do a series of tests and exams. Some of these exams will be at a microscope called a slit lamp. A gonioscopy lens is used by your ophthalmologist to view the angle of your eye to see if it is narrow or open. Your doctor may also use certain machines to take images of your optic nerve. No matter which type of glaucoma you have, you will have to take a visual field test. This test measures your peripheral vision. Glaucoma typically causes loss of a person’s side vision or peripheral vision. It is important to pay attention closely and take this test to the best of your ability for accurate results. Both patients with diagnosed glaucoma and suspected glaucoma have to take visual field tests. If you already have a diagnosis of glaucoma you will typically take a visual field test more often than someone who is just a glaucoma suspect. There are several treatment options for open angle glaucoma. Typically, the patient is offered eye drops or laser by their ophthalmologist. In some states, an optometrist may be able to prescribe eye drops, but laser surgery for glaucoma is best handled by an ophthalmologist who has gone to medical school, and has had surgical training in residency to perform eye lasers. If you or your family member has glaucoma, consider also seeing a fellowship trained glaucoma specialist once a year. Depending on the severity of your glaucoma, you may or may not need a glaucoma specialist. Most general ophthalmologists are capable of managing early to moderate glaucoma, but if it becomes more severe, usually a glaucoma specialist is consulted for their opinion. If your doctor has told you that you are a glaucoma suspect, you will likely have to see the eye doctor once every six months. If your pressure is high, or your corneas are thin, or if you have other risk factors like a strong family history, the ophthalmologist may ask to see you at 4 month intervals. If you have already been started on treatment for glaucoma, you will usually see the doctor every 4 months or every 6 months. Some glaucoma suspects who are very low risk can be followed on a yearly basis. Glaucoma is not a straightforward disease and there are many factors that play into how often a patient should be followed and tested. Sources:https://doi.org/10.1016/j.ophtha.2020.10.022https://www.aaojournal.org/article/S0161-6420(20)31024-1/fulltext
5 min read
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