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Glaucoma What is Glaucoma? • Glaucoma is an eye disease where the eye’s optic nerve is damaged • It is one of the leading causes of blindness in Canada Eye Anatomy • The optic nerve is a • bundle of nerve fibers It carries visual information from the retina to the brain Fluid Circulation • The eye has an • internal fluid circulation system Fluid is produced at the base of the iris Fluid Circulation • The fluid flows through the pupil to the front of the iris Normal Visual Field Healthy Optic Nerve Damaged Visual Field Sick Optic nerve Elevated IOP There are several different forms of glaucoma – – – – Primary Open Angle Glaucoma Low Tension Glaucoma Secondary Glaucoma Angle Closure Glaucoma Primary Open Angle Glaucoma (POAG) • POAG is the most common form of glaucoma • It occurs when the fluid drainage is poor and • • fluid builds up in the eye and the internal eye pressure goes up This increased pressure can cause damage to the optic nerve and vision loss The exact mechanism of damage is still unknown Symptoms of Primary Open Angle Glaucoma • POAG develops gradually and painlessly and has no initial symptoms Vision is normal in the early stages Symptoms of Primary Open Angle Glaucoma • If untreated, peripheral or side vision is slowly lost Tunnel vision Symptoms of Primary Open Angle Glaucoma • Eventually, all vision may be lost Risk Factors for Primary Open Angle Glaucoma • • • • • • • • High Intraocular (Eye) Pressure Over the age of 40 Family history of glaucoma African or Caribbean descent Thin cornea High myopia (Nearsightedness) Diabetes High blood pressure Ocular Hypertension • Some people can have high eye pressure but • • the optic nerve does not get damaged This condition is called ocular hypertension These patients must be closely followed because of the risk of developing glaucoma Low Tension Glaucoma • Low Tension (or Normal Tension) Glaucoma is • • not as common In these cases, the eye pressure is in the normal range but the optic nerve still gets damaged The exact mechanism of damage is still unknown Secondary Glaucoma • Glaucoma can develop as a complication from other conditions including: – – – – – Eye injuries Uveitis (internal eye inflammation) Pigment dispersion Diabetes (Neovascular glaucoma) Steroid use Angle Closure Glaucoma • This type of glaucoma is an emergency • • • situation It occurs when the iris itself blocks the drainage angle and results in a sudden increase in pressure Symptoms include severe eye pain, nausea, eye redness and very blurred vision Immediate treatment is required How is glaucoma detected? • Regular eye examinations by an optometrist • or ophthalmologist are vital to detecting glaucoma A number of tests are performed Glaucoma Tests: Case History • A patient’s medical history, family history and background are important to determine the presence of risk factors Glaucoma Tests: Visual Acuity • A refraction is done to determine best corrected • vision This shows central vision function Glaucoma Tests: Slit Lamp & Gonioscopy • A special microscope called a slit lamp is used to • examine the structures of the eye A gonioscopy lens may be used to view the drainage angle Glaucoma Tests: Tonometry • Eye pressure is measured with an instrument • called a tonometer Three types that are commonly used are: – Goldmann (Perkins) – Non-contact (air puff) Glaucoma Tests: Ophthalmoscopy • Eye drops may be placed in the eyes to dilate the • pupils Special magnifying lenses are used to examine the retina and optic nerve for damage Normal Optic Nerve Suspicious Optic Nerve Glaucoma Tests: Ophthalmoscopy • Advances are being made in digital imaging of the retina Glaucoma Tests: Visual Field Test • Peripheral (side) vision is tested with a perimeter The patient responds to flashes of light in different locations Recent Developments • Recent studies have found that patients with • thin corneas have a greater risk of developing glaucoma Measurement of corneal thickness using an instrument called a pachymeter will become increasingly important Recent Developments • New tools for measuring peripheral vision (visual field) have been developed such as the FDT Recent Developments • Laser technology can now be used to image the retina and optic nerve and measure nerve fiber layer thickness Recent Developments Recent Developments OCT Recent Developments HRT Glaucoma Treatment • The goal is to decrease the eye pressure • The three main categories of treatment are: – Medication – Laser trabeculoplasty – Conventional surgery • Unfortunately, these treatments will not reverse any existing damage but they can slow the progression of the disease Glaucoma Medications • Medications are usually • the first type of treatment used Eyedrops or pills are used to either decrease the fluid production or to increase the fluid drainage Glaucoma Medications • There are several different types of • medication available The right choice will depend on what other medications are being taken, other medical conditions and the effectiveness in decreasing the eye pressure Often, combinations of eyedrops are used • Glaucoma Medications Non Specific Beta Blockers • Levobunolol 0.25%, 0.5%Betagan Timolol0.25%, • • • • 0.5%, 0.1%Gell Nonselective beta-adrenergic blocking agents lower IOP by reducing aqueous humor production Contraindications; Lung : bronchial asthma; COPD Heart :sinus bradycardia; second- and third-degree AV block; overt cardiac failure; cardiogenic shock May cause bradycardia and asystole when used in combination with systemic beta-blockers (may cause additive effects). Precautions May potentiate muscle weakness with myasthenic symptoms (e.g., diplopia, ptosis,) Glaucoma Medications Beta2 Spesific • -Betaxolol • (Betoptic-S)– Beta1-selective adre’ • antagonist, Possibly less pulmonary effects • IOP-lowering effect is slightly less than • • nonselective beta-blockers. Contraindications: bronchial asthma; severe COPD. Heart Same as nonselective beta-blockers Adrenergic Drugs: • Brimonidine (Alphagan) – • lower IOP by reducing aqueous humor • • • • • • • • production Coadministration: Tricyclic antidepressants may decrease effects . CNS depressants (eg, barbiturates, opiates, sedatives) may potentiate effect. Caution in CVS disease, depression, cerebral or coronary insufficiency, orthostatic hypotension, and Raynaud syndrome; Apraclonidine 0.5%, 1% (Iopidine) Selective alpha-adrenergic agonist Monitor pulse and BP with CVS drugs; Not for use concurrently with MAOIs Carbonic Anhydrase Inhibitors • TOPICAL – Dorzolamide (Trusopt) 2%; Brinzolamide (Azopt) 1%; – Reversibly inhibits CA, reducing H+ secretion at renal tubule, increases renal excretion of Na / K- CO2, and H2O to decrease production of aqueous humor. – Azopt may cause less ocular discomfort • Systemic – Acetazolamide- Methazolamide – CI :Hx metabolic or ketoacidosis, hepatic insufficiency, severe COPD, kidney stones, sulfa allergy, or blood dyscrasias (eg, sickle cell anemia); – contraindicated in first trimester of pregnancy because of possibility of teratogenicity Prostaglandines- Prostamides Xalatan – Travatan – Lumigan • Decreases IOP by increasing outflow of aqueous humor through Uveoscleral pathways • Long-term use can cause darkening of iris and thickening of lashes; use with care in monocular therapy for cosmetic reasons; do not administer while wearing contact lenses Pilocarpine – The oldest drug • Pilocarpine 1%, 2%, 4% - A naturally occurring • • • alkaloid, pilocarpine Mimics the muscarinic effects of acetylcholine at postganglionic parasympathetic nerves. Directly stimulates cholinergic receptors in the eye, decreasing resistance to aqueous humor outflow Facilitates Convetional outflow ( TM) Laser Trabeculoplasty • This laser treatment helps to increase the • fluid drainage The surgeon uses a laser to burn the spongy meshwork that is located in the drainage angle Conventional Surgery • With this treatment, the surgeon creates a • new opening in the eye for the fluid to drain out from If the new opening becomes plugged or narrowed, further surgery may be required Coping with Vision Loss • Many patients with sight loss due to glaucoma can benefit from low vision aids • Optometrists can perform low vision assessments and prescribe magnifying devices to enhance both distance and reading vision These aids will not restore sight to normal • levels but they allow people to maximize the amount of vision remaining Early Detection and Treatment • Regular eye health examinations are important to detect glaucoma early so that treatment can be started and vision loss can be prevented