More than meets the Eye

Retinal Detachment is an eye condition in which a layer of tissue called the retina is pulled away from it's typical position inside the eye. The retina's function is to receive light that the lens has focused, convert this light into neural signals, and send these signals to the brain for visual recognition via the optic nerve which is connected to the brain. The retina is a layer of nervous tissue which covers the inside of the back two-thirds of the eyeball, the retina processes light through photoreceptor cells, these are light-sensitive cells and there role is to detect colour and light-intensity.

Papilledema is a medical condition in which the optic nerve at the back of the eye become swollen. Papilledema can be life-threatening so it is very important that the patient receives immediate medical intervention. Papilledema occurs when there is a build-up of intracranial pressure (pressure within the brain) and cerebrospinal fluid is placed on the optic nerve, it can occur in one or both eyes. Papilledema can be caused by a number of serious medical conditions such as a brain tumour, severely high BP (also known as hypertensive crisis), bleeding within the brain or trauma to the brain. 

Cystoid Macular Oedema (CME) is a painless condition in which the central retina or macula is affected. When a patient presents with Cystoid Macular Oedema, Optical Coherence Tomography (OCT) reveals multiple cyst-like pockets of fluid appear within the macula and around the fovea and result in retinal swelling or edema causing retinal thickening of the macula due to disruption of the typical blood-retinal barrier, this leads to leakage from the perifoveal capillaries, resulting in fluid accumulation within the intracellular spaces of the retina, primarily within the outer plexiform layer and inner layers of the retina. Thickened fovea, possible small elevation about retinal pigment epithelium (RPE) and central map thickness may also be present on OCT examination.

Cataracts are a common occurrence in patients over 65, over 50% of people over 65 have a form of cataract development in either one or both eyes, many of these cataracts can be effectively treated with surgery. A cataract refers to the loss of  transparency of the lens resulting in clouding of the lens in the eye. Cataracts are a common cause of visual complaints in patients over the age of 50 because vision can become blurred or dim as a result of the cataract blocking the light from passing through the lens to the retina at the back of the eye for processing, the lens is a transparent elastic body located behind the iris (the coloured part of the eye). The function of the lens is to bend light rays to give a clear image to the retina located at the back of the eye. Some symptoms of cataract development include double vision (the cloudiness of the lens may be in more than one place, resulting in the light rays being split when they reach the retina, causing the patient to experience double vision), poor vision in bright light, change of colour perception (as the cataract developments in the lens, its center becomes increasingly yellow in colour, giving everything a yellowish appearance).

Optic Neuritis occurs when the nerve fibers in the optic nerve become inflamed, this cause Optic Neuritis commonly results in temporary loss of vision and usually only occurs in one eye, but it is possible for Optic Neuritis to affect both eyes at the same time. In Optic Neuritis (ON), the covering of the optic nerve called the sheath, which consists of a substance known as myelin, becomes inflamed. Optic Neuritis is also known as an acute inflammatory demyelinating disorder. When the myelin lining (sheath) becomes damaged as a result of this inflammation, the optic nerve's function is impaired cannot efficiently transmit signals from the eye to the brain and this leads to decreased vision in the affected eye(s). Signs of optic neuritis may be the first indication of Multiple Sclerosis (MS), a progressive, neurological condition, in a patient. The cause of Optic Neuritis (ON) is currently unknown but experts believe it can flare up quickly as a result of an infection or an immune condition such as lupus. Optic Neuritis (ON) most commonly occurs in patients between the age of 20 and 50 years old, it is three times more likely to occur in females. Optic Neuritis is the most common optic nerve condition to affect younger people, the average age for an Optic Neuritis attack to occur is 31 years old, but this does not rule out people over 40 years old, who may also develop Optic Neuritis (ON).

Central Retinal Vein Occlusion (CRVO) is a condition in which a blockage occurs in the vein which carried blood away from the retina at the back of the eye. this blockage can be partial or complete. This causes blood and excess fluid to leak from the vein into the surrounding area of the retina, this in turn causes damage to the retina which can result in blurred vision or potential loss of vision in some cases. Most patients with CRVO develop it in one eye. There are two main types of CRVO, these are known as Non-Ischaemic and Ischaemic CRVO. Non-Ischaemic CRVO can be a less severe initial loss of vision, with a greater chance of recovering vision. In Ischaemic CRVO, the initial vision loss is more severe, there is lack of sufficient oxygen to the retina, leading to significant complications. Ischaemic CRVO is less common but can result in long-term vision loss. Central Retinal Vein Occlusion may lead to the development of various complications, these include high pressure within the eye (glaucoma), macular oedema, and growth of new blood vessels (also called neovascularisation)

Retinitis Pigmentosa is a rare, degenerative disease that is typically hereditary and can result in severe visual impairment. In some cases, people can develop Retinitis Pigmentosa if they have no family history and in other cases some people can develop this condition in collaboration with another disorder, such as waardenberg syndrome (a genetic disorder present at birth) and alport syndrome (a genetic condition categorized by eye abnormalities and hearing loss). Retinitis Pigmentosa is usually caused by a recessive gene, this means the abnormal gene must be inherited from both parents. Some cases of RP have been associated with genetic mutations on the X chromosome. Other cases of RP are as a result of a dominant gene, meaning that patients who present with this disease if they inherit the mutated gene from just one parent.

Diabetic Retinopathy is a complication of diabetes in which the retina is damaged as a result of high blood glucose levels. Over a period of time, too much sugar in your blood can result in the blockage of tiny blood vessels that nourish the retina, as a result of this, the eye then attempts to grow new blood vessels, unfortunately these new blood vessels do not develop effectively and leak easily. Diabetic Retinopathy can affect anyone who suffers from type I or type II diabetes, the longer the patient has diabetes and the less controlled it is increases the risk of the patient developing Diabetic Retinopathy. There are two types of Diabetic Retinopathy:

The retina is the thin layer that lines the back of the eye internally, it located near the optic nerve. The function of the retina is to receive the light that the lens has focused, convert it into neural signals, and send these neural signals to the brain via the optic nerve for visual recognition. The retina is the innermost layer of the wall of the human eye. It is in close contact with the vitreal cavity on one side and with the choroid (of the uveal layer) on the other side.

Epiretinal Membrane (ERM) are a frequent finding by an Optometrist, particularly in older patients. An Epiretinal Membrane (ERM) is a semi-translucent thin layer of fibrous tissue consisting of naturally occurring cells that can develop on the surface or above the surface of the macula and can result in issues with central vision such as decreased vision and/or metamorphopsia which is a visual defect that leads to linear objects looking curved. Most Epiretinal Membranes occur because the vitreous (the gel-like fluid inside the eye which fills the space between the lens and the retina) pulls away from the retina. Epiretinal Membrane most commonly occurs in patients over the age of 50, it may happen following eye surgery or as a result of inflammation within the eye. An Epiretinal Membrane (ERM) is commonly described as scar tissue on the retina, other names for an ERM include a macular pucker or cellophane maculopathy. Epiretinal Membrane (ERM) may impair vision if the layer of cells begins to shrink, allowing the retina to wrinkle up beneath it, resulting in blurred and distorted vision. An Epiretinal Membrane (ERM) does not lead to complete sight loss as it does not impair peripheral vision. In some cases, Epiretinal Membrane (ERM) does not cause vision problems or surgical intervention, but does require monitoring to see if the ERM progresses, may ERMs do not worsen and may never require medical intervention.

Toxoplasmosis is a condition that results when a patient is infected by the Toxoplasma gondii parasite, it is a notable disease in Ireland. Toxoplasmosis is the most common cause of eye inflammation in the world. A patient is typically affected by Toxoplasmosis by consuming undercooked meat, mother-to-child transmission during pregnancy (congenital toxoplasmosis) or exposure to cat faeces that contain the Toxoplasma gondii parasite. Most patients who are infected with Toxoplasmosis do not show any symptoms of the disease, when symptoms are presented they typically are described as "flu-like" symptoms such as, fever, swollen lymph glands, headache, fatigue and body ache. Patients who suffer with underlying conditions such as HIV/AIDS or patients who have compromised immune systems are more at risk of developing Toxoplasmosis as their immune systems finds it difficult to fight the infection. The parasite which causes Toxoplasmosis (Toxoplasma gondii) has the ability to form microscopic cysts within muscle tissue and can harbour in the body for many years, in some cases it can reoccur.

Uveitis occurs when the middle layer of tissue in the eye wall, known as the uvea, becomes inflamed. The Uvea helps to provide nutrients to the eye, it consists of three parts from the front to the back of the eye, these are the ciliary body, the iris and the choroid. Uveitis can develop in one or both eyes, it can be serious and lead to permanent loss of vision, because of this it is very important to diagnose and seek treatment for Uveitis as quickly as possible to prevent damage from occurring. Uveitis may be caused by a number of factors, these include an eye injury or previous eye surgery, an autoimmune disease or an infection. Most cases of Uveitis improve with steroid medication, typically if Uveitis is present at the front of the eye, eye drops are prescribed to the patient, if Uveitis is present in the middle or at the back of the eye, infections and tablets are often used to treat the condition. In some cases, Uveitis can lead to further complications, such as Glaucoma or Cataracts if the condition is not identified early.

A retinal tear occurs when the vitreous, the clear gel-like substance that fills the back cavity of the eye, pulls abnormally on the retina (abnormal vitreo-retinal adhesion), causing the retina to subsequently tear. Retinal tears are typically painless, the most common symptoms presented by a patient with a retinal tear include, sudden short flashing lights in the affected eye, blurred vision, a "curtain-like" shadowing in peripheral vision, and a sudden development of floaters. Risk factors related to retinal tears include trauma, previous eye surgery, a high degree of myopia, aging, family history of retinal tears or detachment, diabetes which is not under control and thinning of the retina. Most retinal tears develop as a result of Posterior Vitreous Detachment (PVD), this is when the vitreous is unable to fill the vitreous cavity of the eye and subsequently separates from the retina, after 1 - 3 months, the volume of the vitreous will decrease further, causing the sides of the vitreous to also pull away from the retina, causing a complete PVD.

Keratitis is a painful, inflammatory eye condition that primarily affects the cornea (the transparent outer layer of the eye which helps the eye to focus), it is a relatively common condition. Symptoms of Keratitis include red eyes, discharge from eye, pain and irritation in the eye, a feeling of something in the eye, difficulty opening the affected eye, photophobia (light sensitivity), profuse tearing, blurriness of vision and decrease in vision. The extremity of these symptoms depend on the cause and severity of the condition. The most common cause of Keratitis is an injury to the eye or infection, other causes of Keratitis include ocular surface disease and compromised immunity. Patients who wear contact lenses are more likely to develop Keratitis than those who do not wear them. Keratitis can be serious if not identified and treated, untreated Keratitis can result in vision loss or blindness. Keratitis is treatable if diagnosed early. Complications of Keratitis include corneal ulcers, permanent corneal scarring and even glaucoma.

A Retinoblastoma is a rare form of eye cancer. There are a number of signs of a Retinoblastoma, these include an unusual white reflection of the eye, which is apparent in ohotos when a camera flash is used, (in a normal, healthy eye, the eye may typically appear red when exposed to a camera flash) or when it is noticed in a dark room, the eye may appear red and inflamed, a colour change in the iris, inability to focus objects (vision is poor), lack of control in terms of eye movement (this is typically when both eyes are affected by Retinoblastoma), a squint may also be present in a patient with a Retinoblastoma. Retinoblastoma is cancer of the retina (the light sensitive layer located at the inferior of the eye). Retinoblastoma usually affects young children under the age of 5, during the premature stages of a baby's development, the cells that form the retina develop rapidly and then stop developing, rarely, one or more of these cells grow continuously and form a Retinoblastoma. In some cases, A Retinoblastoma may be caused by a defected gene, this may be inherited from a parent or in other cases a gene mutation may occur in the early stages of the child's development within the womb. The cause of the remaining 60% of Retinoblastoma cases is unknown, in these cases where the cause of the condition is unknown, there is no faulty gene present and typically one eye is affected. Retinoblastoma can either be extraocular (where the retinoblastoma spreads beyond the eye to the tissue surrounding the eye) or intraocular (where the cancer is limited to within the eye), usually, Retinoblastoma is identified prematurely and treatment is typically successful - this avoids it from spreading outside the eye and becoming extraocular. Extraocular retinoblastoma is more complex to treat, but is rare.

The term Hypertensive Retinopathy (HR) means the vascular damage to the retina which is caused by Hypertension or High Blood Pressure. High Blood Pressure is a chronic condition in which the force of the blood against the arteries is too high, this force results from blood pumping away from the heart and into the arteries, as well as the force that results as the heart rests between heartbeats. When blood travels through the body at a higher pressure, arterial tissue can become stretched and this leads to them eventually becoming damaged. Overtime, high blood pressure can lead to retinal blood vessel damage, impairment of the retina's function, and pressure on the optic nerve, which results in vision problems, this condition is known as Hypertensive Retinopathy (HR). When a patient's blood pressure is too high, the retina's blood vessel walls may become thicker, this may result in the blood vessels becoming narrow and as a result causes lack of blood flow to the retina as the path is restricted, in some cases, this can lead to the retinal swelling. Prolonged High Blood Pressure or Hypertension is the typical cause of Hypertensive Retinopathy, this means that the patient's blood pressure has been consistently high for a long period of time. Risk factors of Hypertensive Retinopathy include, diabetes, smoking, being overweight, an unhealthy diet, consuming excessive alcohol and if the patient has an underlying condition such as atherosclerosis or heart disease, it is important to note that high blood pressure can also be hereditary. According to research, Hypertensive Retinopathy is more common in patients of African origin, the condition is also known to be more common in females compared to males.

Ocular Hypertension results when the intraocular pressure is in the higher than normal range, this means the front of the eye is not draining fluid efficiently, this leads to a build up of eye pressure. The term Ocular Hypertension is used to distinguish patients with eye pressure above the normal range from patients who are currently suffering from Glaucoma. Ocular Hypertension typically has no signs of symptoms, but patients with this condition are at increased risk of developing glaucoma. In patients with Ocular Hypertension, the optic nerve appears normal and there is no vision loss, it is important that these patients have regular comprehensive eye examinations in order to be monitored for glaucoma, patients with Ocular Hypertension are known as "glaucoma suspects".