Eye Conditions portable display format for medical students
- 1. EYE CONDITIONS Dr. S M’bayo
- 2. Anatomy and Physiology of the Eye
- 3. Outline Anatomy External/Accessory features Eyeball Structure - Fibrous layer -Vascular layer -Nervous layer Internal structures - Anterior cavity -Vitreous Chamber -lens Physiology - Image Formation Physiology of Vision
- 5. Eye Lids Also called PALPEBRA Two on each eye: upper and lower Two main functions: -Protection of the eyeball -Secretion, distribution and drainage of tears
- 7. Eye Brows and Eye Lashes Hair structures above and on the outline of the eyes respectively Protective function against: -direct sunlight -dust -sweat -foreign bodies
- 9. Lacrimal Gland and ducts o Situated in the upper, outer areas of the eye orbits o exocrine glands that secretes tears o about 6 to 12 ducts that empty tears into the surface of the conjunctiva of the upper eyelid
- 11. Conjunctiva A mucous membrane lining the eyelids and covering the anterior eyeball Two parts: Bulbar: covers the sclera Palpebral: lines the inside of the eyelids
- 12. Tear film Lipid layer – secreted by the Meibomian gland Aqueous layer – produced by the lacrimal gland Mucous layer - secreted by microscopic goblet cells in the conjunctiva
- 13. Eye Muscles • Lid Retractors •Extraocular Muscles
- 14. Lid Retractors These are responsible for opening the eyelids • Levator Palpebrae Superioris muscles (upper lid) •Lower lid retractor - inferior rectus, extends with the inferior oblique and inserts into the lower border of the tarsal plate
- 16. Extraocular Muscles are respondsible for eyeball movements Superior rectus – upward/superior Inferior rectus – downward/inferior Medial rectus – inward/medial (toward the nose) Lateral rectus – outward/lateral (away from the nose) Superior oblique – down and out Inferior oblique – up and out
- 18. Eyeball The eyeball is about 2.5cm in diameter About one-sixth is exposed It is composed of three layers: -Fibrous layer - Vascular Layer - Nervous layer.
- 19. Fibrous layer Cornea and Sclera They form the a spherical shell which makes up the outer wall of the eyeball. SCLERA It is the white part of the eye Mostly made up of dense connective tissues It covers the eyeball except the cornea Maintains eyeball shape Serves as an attachment for extraocular muscles Avascular (apart from small vessels on its surface) CORNEA Transparent layer Covers the iris Refracts light
- 20. Vascular layer Choroid -Has numerous blood vessels The network of blood vessels supply oxygen and nutrients - Contains melanocytes Absorbs excess light the choroid continues anteriorly to form the Ciliary body and the iris
- 21. Ciliary body A continuation of the choroid anteriorly It has muscles that control the thickening of the lens (ciliary muscles) Ciliary muscles are attached to the lens by the suspensory ligament(zonules) Ciliary processes produce aqueous humor
- 22. Iris The coloured portion of the eye Suspended between the cornea and the lens Contains melanocytes and smooth muscle fibers The muscles control pupillary constriction and dilatation Constriction– sphincter pupillae (circular) Dilatation – Dilator pupillae (radial) The iris divides the anterior portion of the eye into two chambers (anterior and posterior)
- 23. Nervous Layer (Retina) Inner layer Has two layers -pigmented layer - neural layer Pigmented layer contains melanin which absorbs light Neural layer consists of three layers: -Photoreceptor layer -Bipolar neuron layer……..horizontal and amacrine cells -Ganglion cell layer
- 24. Photoreceptors Two types: Cones -bright light stimulates cones - about 6 million cones in each retina Rods -about 120 million rods in each retina - dim light stimulates rods
- 25. Macula - highest concentration of cones Fovea centralis - centre of macula - contains only cones, no rods Optic disc (blind spot) - contains no photoreceptors
- 26. Lens A transparent crystalline biconvex structure immediately behind the iris Suspended from the ciliary body by threadlike structures called zonules Focuses light on the retina
- 27. Anterior compartment • Aqueous humor -fluid that nourishes the lens and epithelial cells -helps to refract light onto the retina The anterior compartment is divided into two chambers by the Iris. Namely: The anterior(in front of the iris) and posterior chamber(behind the iris) Posterior compartment • Vitreous humor - clear gel -helps to refract light onto the retina
- 28. Optic Nerve • Transmits impulses from the retina to the brain •The blind spot or optic disc is located at the optic nerve head Retinal Blood vessels • Arteries transmit oxygen and nutrients •Veins carry deoxygenated blood from the eye.
- 30. Physiology Photoreceptors RODS CONES Sensitive to dim light Sensitive to bright light More peripherally located More centrally located About 120 million About 6 million Vision in all shades of grey Color vision No edge detection Edge detection Contains the pigment Rhodopsin (Retinol and Opsin) Contains the pigment Photopsin
- 31. Layers of the retina - Pigmented layer - Photoreceptor - Bipolar neurons - Ganglion cells (the axons form the optic nerve) The optic nerve is a bundle of nerve fibres ie the axons of the ganglion cells, that carry visual message from the retina to the brain
- 32. Mechanism Visual pathway Retina Optic Nerve Optic Chiasma Optic Tract Lateral Geniculate nucleus of the Thalamus Superior and Inferior Retinal Fibres Visual cortex (Calcarine sulcus of the occipital lobe)
- 33. Pupillary Light Reflex This is simultaneous and equal constriction of the pupils in response to the stimulation of one eye by light. It involves the muscles of the Iris Sphincter pupillae (circular) – pupillary constriction (PNS) Dilator pupillae (Radial)– pupillary dilation (SNS) There are two types: Direct reflex – constriction of the pupil on the eye that received the light stimulus Consensual reflex- simultaneous pupillary constriction of the other eye
- 34. Accomodation This is the mechanism by which the eye changes refractive power by altering the shape of the lens in order to focus objects at variable distances It involves contraction and relaxation of the ciliary muscles Far objects…..Ciliary muscle relaxes …….lens flattens Near objects…..Ciliary muscle contracts…..lens bulges
- 35. Examination of the eye 1. Visual Acuity – measured using the Snellen Chart (patient is positioned 6 metres or 20 feet away) or the Near Card 2. Pupils – using a pen light, measure the diameter of the pupils in dim and bright light. Pupils should be equal, round and reactive to light. Check for the direct and consensual light reflex. 3.Extraocular movement – three cranial nerves are involved (LR6,SO4,A3). Sit infront of the patient. Using your index finger, start at the centre and draw the cardinal H and end at the centre 4. Retinal Exam – exam should be done in a dim light room or after giving a pupillary dilator and an ophthalmoscope is used to look at the retinal structures.
- 36. RED EYE (“Apollo”) /Conjunctivitis This is inflammation of the conjunctiva, which is the transparent mucous membrane lining of the eyelids and the eyeball. There are two main causes: Infectious- due to bacterial or viral infection Non-infectious- due to allergies or irritants
- 37. Conjunctivitis
- 38. Signs and Symptoms Redness Pain Swelling of the eyelids Eyelids sticky with crust formation, noticed esp on arising from sleep Excessive tear flow Pus discharge Itchiness Blurred vision Increase sensitivity to light
- 39. Causes/Diagnosis Infectious -Viral infections is the most common cause -Bacterial infections Non-infectious -Allergies- dust, pollen -Irritants- smoke, dirt, shampoos, prolonged use of contact lenses Infectious conjunctivitis is highly contagious Diagnosis is based on symptoms and physical examination of the eye
- 40. Treatment This depends on the cause Viral conjunctivitis does not usually require treatment and symptoms can resolve in about 2-3 weeks. Antiviral medications may be prescribed Bacterial conjunctivitis require topical antibiotics (eye drops or ointments) Warm compresses can sooth symptoms of infectious conjunctivitis ie viral or bacterial Allergic conjunctivitis responds to antiallergic medications, such as: antihistamines, steroids, anti-inflammatory drugs. Cool compresses may also be helpful. Also avoiding triggers for an allergic reaction.
- 41. Prevention Maintaining good hygiene helps prevent the spread of conjunctivitis Hand washing Avoid touching and rubbing the eyes Avoid sharing towels or other personal items Handle contact lenses properly and follow a regular cleaning regimen
- 42. Ophthalmia Neonatorum This is inflammation of the conjunctiva during the first month of life. This is usually caused by a bacterial infection. Signs: Redness, fluid discharge and lid swelling Treatment Warm compress Daily saline eye irrigation Oral or parenteral antibiotics for about 1-2 weeks
- 43. Blurred Vision Decreased clarity or sharpness in vision - Uveitis- inflammation of the uvea, which is the middle layer of the eyeball. It can be : Posterior Uveitis—Chorioretinitis Anterior Uveitis– Iritis Panuveitis– simultaneous inflammation of the anterior and posterior portions of the uvea
- 44. Chorio-retinitis This is inflammation of the choroid and the retina of the eye. It is a posterior uveitis. Causes include: -Toxoplasmosis, Cytomegalovirus infections which could be due to Immunosuppressive conditions like HIV -Syphilis -Tuberculosis -Sarcoidosis -Ocular Histoplasmosis -Ebola virus -Herpes virus
- 45. Signs and Symptoms include: Seeing floating black spots Pain/redness Excessive tears Sensitivity to light Blurred vision Treatment Steroids Antibiotics Managing other underlying causes like HIV
- 46. Iritis This is anterior uveitis. It is inflammation of the iris. It can affect one or both eyes. Causes include: - can be mostly idiopathic -Trauma -complications of other diseases like Tuberculosis Sarcoidosis Lupus - Herpes simplex virus Iritis is not contagious
- 47. Signs and Symptoms: Redness/pain Excessive tears Blurred vision Photophobia (sensitivity to light) Diagnosis is made by the presence of inflammatory cells on the anterior chamber of the eye. Treatment Anti-inflammatory and steroid drugs (usually topical) Dilator eyedrops
- 48. Glaucoma This is a group of diseases characterized by: -optic neuropathy -specific pattern of visual field defect -raised intraocular pressure (Normal Intra ocular pressure is 10-21mmhg) Damage to the optic nerve is an irreversible process. Therefore, Glaucoma is a common cause blindness. It can be classified as: -Congenital and developmental Glaucoma -Primary Glaucoma -Secondary Glaucoma
- 49. CONGENITAL GLAUCOMA This is a rare condition. It is as a result of maldevelopment of the angle structures, leading to impaired aqueous fluid outflow and thus a raised intraocular pressure (IOP). It can be classified into: True congenital glaucoma(40%): IOP becomes elevated in intrauterine life and the child is born with ocular enlargement. Infantile glaucoma (50%): is manifested before the child is 3 years old. Juvenile glaucoma(10%): manifests between 3-16 years. Symptoms and Signs - Photophobia, lacrimation, blepharospasm, enlarged eyeball - Corneal edema - Sclera becomes thin and appears blue - Lens becomes flat - IOP is invariably high
- 51. Primary open angle glaucoma This is usually bilateral with asymmetry in onset. There is slow progressive rise in IOP (due to increase resistance within the aqueous drainage system), glaucomatous optic nerve damage and visual field loss. Risk factors include: - Age - Race - Family history - Diabetes and Systemic hypertension - Alcohol consumption - Cigarette smoking - Myopia - Disc hemorrhage CLINICAL FEATURES Commonly asymptomatic, mild headache, ocular pain, minimal blurring of vision, subjective occasional visual field defect, raised or normal IOP, normal cornea and conjunctiva, optic nerve cupping
- 52. Primary angle closure glaucoma This occurs when the iris shifts anteriorly and blocks the drainage angle and results in a sudden increase in the IOP. This type of glaucoma is an emergency. Risk factors include: - Race ( higher in south-east Asians, Chinese and Eskimos) - Age (increases with age, >40yrs) - Gender( 2-4 times more in females) - Family history (first degree relatives) - Personality (anxious) - Hyperopia (farsightedness) CLINICAL FEATURES Sudden onset of acute pain in the eye and head, diminution of vision, colour halos around the bulb, lacrimation, lid edema, nausea and vomiting, acute red eye, hazy cornea, reduced visual acuity, vertically oval or mid dilated pupil.
- 53. Secondary glaucoma This is where the raised IOP is associated with primary ocular or systemic disease. These include: - Glaucomas associated with irido-corneal endothelial syndrome - Glaucomas associated with intraocular hemorrhage - Pseudoexfoliative glaucoma - Steroid-induced glaucoma - Traumatic glaucoma - Ciliary block glaucoma -Glaucoma associated with intraocular tumors - Lens –induced glaucoma
- 54. Management MEDICAL TREATMENT 1. Beta-blockers (Timolol, Levobunolol, Betaxolol)- to lower the IOP by reducing the aqueous secretion by effect on beta receptors in ciliary processes 2. Carbonic anhydrase inhibitor (Dorzolamide) – inhibits carbonic anhydrase enzyme, thus reduces aqueous humor formation. 3.Prostaglandin analogue (Latanoprost, Tarvoprost, Bimatoprost)- increase the uveo-scleral outflow of aqueous humor. 4. Miotics (Pilocarpine) – mechanically increases the aqueous outflow contracting ciliary muscles 5. Hyperosmotic agents (Mannitol, Oral Glycerol) SURGICAL TREATMENT 1. Argon Laser Trabeculoplasty 2. Trabeculectomy
- 55. Ocular Onchocerciasis Onchocerciasis, also known as river blindness or Roble’s disease, is a parasitic infection caused by a roundworm, Onchocerca volvulus. It is the world’s second leading infectious cause of blindness’ The parasite is transmitted to humans through the bite of a black fly of the genus Simulium This condition affects the skin and the eyes Ocular involvement: Any part of the eye from the conjunctiva and cornea to uvea and posterior segment, including the retina and optic nerve can be affected.
- 56. Treatment Infected people can be treated with two doses of Ivermectin, six months apart, repeated every three years’ Ivermectin treatment is particularly effective because it only needs to be taken once or twice a year. Prevention Larvicide spraying of fast-flowing rivers to control black fly population.
- 57. Corneal ulcer This is the discontinuation in the normal epithelial surface of the cornea, associated with necrosis of the surrounding corneal tissue. It is known as Keratitis. It can be classified based on: 1. Aetiology -Infective: Bacterial, Viral, Fungal, Protozoal. - Non infective/Sterile: Neuroparalytic, Neurotrophic, Vitamin A deficiency, Mooren ulcer 2. Location - Central, Paracentral and Peripheral 3. Involvement of the corneal layers - Superficial and Deep
- 59. Predisposing factors Local Systemic Ocular trauma Malnutrition Entropion Diabetes Mellitus Exophthalmos Alcoholism Contact lens use Drug addiction Prolong use of local steroids Malignancy Xerophthalmia Immunosuppresive drugs Trichiasis Herpes Simplex Virus, HIV
- 60. Clinical presentation Symptoms Signs Pain Swollen eyelids (blepharitis) Watering (hyperlacrimation) Marked blepharospasm Photophobia Corneal ulcer Blurred vision Hypopyon (pus in the anterior chamber) Redness Pupil constriction Raised intraocular pressure Conjunctival hyperemia
- 61. Management Depending on the cause: 1. Antibiotics, Antifungals, Antivirals (local or systemic therapy) 2. Topical Steroids, topical amoebicides, analgesics 2. Local Care: - debridement of ulcer -Intraocular pressure control
- 62. Complications 1. Secondary glaucoma 2.Perforation of corneal ulcer 3. Corneal scarring 4. Descemetocele 5. Anterior Uveitis
- 63. Cataract This is the clouding/opacity within the crystalline lens, leading to decrease in vision. The lens is a biconvex structure, attached to the ciliary process by the suspensory ligaments, between the iris and the vitreous humor. It is non-vascular, colourless and transparent It is divided into the nucleus, cortex and the capsule (the whole lens is enclosed within an elastic capsule) The lens helps to refract incoming light and focus it onto the retina
- 65. Causes 1.Congenital- Familial, Intrauterine infections, Maternal drug ingestion 2. Age- Elderly 3. Metabolic- Diabetes Mellitus, Hypocalcemia, Wilson’s disease, Galactosemia 4. Drug-induced- Corticosteroids, Miotics, Amiodarone, Phenothiazines 5. Trauma and Inflammatory- Post intra-ocular surgery, Uveitis 5. Disease associated- Down’s Syndrome, Dystrophia Myotonica, Atopic Dermatitis
- 66. Classification Cataracts can be classified based on: 1. Morphorlogy a. Subcapsular cataract: Anterior subcapsular and Posterior subcapsular b. Nuclear cataract: involving the nucleus of the lens c. Cortical cataract: wedge shaped or radial spoke-like opacities d. Polar cataract: central posterior part of the lens 2. Degree of maturity a. Immature cataract: one in which the lens is partially opaque b. Mature cataract: here, the lens is completely opaque c. Hypermature cataract: shrunken and wrinkled anterior capsule due to leakage of fluid out of the lens d. Morgagnian cataract: a hypermature cataract in which liquefication of the cortex has allowed the nucleus to sink inferiorly.
- 68. Clinical Presentation Symptoms and Signs include: - painless, progressive blurred vision - glare - monocular diplopia (double vision) - Leukocoria (white pupillary reflex) - Decreased visual acuity (worse in bright light)
- 69. Management Treatment includes: 1. Glasses 2. Better lighting 3. Surgery a. Phacoemulsification b. ICCE (intracapsular cataract extraction) c. ECCE (extracapsular cataract extraction) Complications of cataract include: - endophthalmitis (infection of the eye) - Corneal edema - Hyphema (bleeding in the front of the eye) - Retinal detachment
- 70. Blepharitis This is the subacute or chronic inflammation of the eyelid margins. It is a common eyelid inflammation that is sometimes associated with a bacterial eye infection. It is classified into: - Anterior and Posterior blepharitis. Anterior blepharitis: Bacterial, Seborrheic and parasitic Posterior blepharitis: Meibomitis (Meibomian gland dysfunction) CLINICAL FEATURES Chronic irritation Itching Mild lacrimation Mild photophobia Yellow crusts at the root of the cilia Conjunctival hyperemia Inflamed lid margins
- 71. Treatment - Lid hygiene - warm compress - Antibiotics (oral of topical, based on the cause) - Weak topical steroids - Oral anti-inflammatory drugs
- 72. Stye and Chalazion A stye or hordeolum is a small , painful lump on the inside or outside of the eyelid. It is actually an abscess usually caused by a staphylococcus infection. A chalazion is very different from a stye and is not an infection. It is a firm, round, smooth, painless bump, usually some distance from the edge of the eyelid. It is a local tissue reaction to oily glandular secretions that were unable to reach the lid surface because the duct was blocked by debris. Styes and chalazia are usually harmless and rarely affect the eyeball or eyesight. They tend to occur at any age and periodically recur. Clinical features Sytes: red, hot, tender swelling near the edge of the eyelid Chalazion: a painless smooth round bump in the mid-portion of the eyelid. Treatment They mostly heal on their own within a few days. Warm compress helps with pain relief and with healing. Antibiotics are usually prescribed to reduce bacterial growth.
- 74. Ocular injuries Damage or trauma inflicted on the eye by an external means. It includes both surface and intraocular injuries. Soft tissues and bony structures around the eye may be involved. Ocular injuries are classified as: Open globe, closed globe and periocular OPEN GLOBE: these injuries have a full thickness breaks of the eye wall, which is composed of the sclera and cornea. They are further described as: - Open globe ruptures: full thickness injuries caused by blunt trauma - Open globe lacerations: full thickness injuries caused by sharp objects CLOSED GLOBE: these do not have full thickness breaks of the eye wall. They are further divided into: - Lamellar lacerations: partial thickness wound to the eye wall. - Contusions: no eye wall wound.
- 75. The following injuries are also lamellar lacerations: Conjunctival laceration Partial thickness scleral laceration Partial thickness corneal laceration Other closed globe injuries include: Corneal abrasion Conjunctival abrasion Hyphema Traumatic Iritis Traumatic Mydriasis Lens dislocation Vitreous Hemorrhage Retinal detachment
- 76. Periocular injuries These include: Eyelid abrasions- superficial skin injury not requiring surgical repair Eyelid lacerations- full thickness skin injury usually requiring surgical repair Canalicular lacerations- full thickness eyelid skin injury which includes the lacrimal drainage system. Periocular ecchymoses- skin bruising, which may indicate more serious underlying injury. Orbital fractures- fractures of any of the bones making up the socket and surrounding the eye. Extraocular muscle entrapment- prolapse of extraocular muscle(s) into the defect created by a fractured orbital bone Orbital foreign bodies- any foreign body present in the eye socket but outside the globe. Orbital compartment syndrome- elevated intraorbital pressure from infection, bleeding or inflammation, causing poor motility or possible ocular ischemia.
- 78. Refraction Refraction of light occurs when light passes from one medium to another of different refractive index (ie density). The refractive components of the eye include: the cornea, the lens, the axial length. Light rays are focused on the retina because they are refracted by passing through the cornea and lens. The refractive power of the cornea is constant, that of the lens is modifiable with accommodation and the axial length of the eye is constant except under certain conditions. Emmetropia: is adequate correlation between axial length and refractive power. Parallel light rays fall on the retina. Ametropia: is when there is a mismatch between the axial length and the refractive power. Parallel light rays do not fall on the retina. Otherwise known as a refractive error. It includes: -Nearsightedness (Myopia) -Farsightedness (Hyperopia) -Astigmatism (both nearsightedness and farsightedness) -Presbyopia (loss of near vision with age)
- 79. Myopia(nearsightedness) Parallel rays converge at a focal point anterior to the retina. Causes: - excessive long eyeball (axial myopia), which is more common. - excessive refractive power (refractive myopia) - Increase in the curvature of the cornea or the surfaces of the crystalline lens. Clinical features: Blurred distance vision Squint in an attempt to improve uncorrected visual acuity, when gazing at a distance Headache Treatment: concave lenses, clear lens extraction
- 80. Hyperopia (farsightedness) Parallel rays converge at a focal point posterior to the retina. Causes: - excessive short eyeball (axial hyperopia), which is more common. - insufficient refractive power (refractive hyperopia) - lens changes (cataract) Clinical features: ‘Eye strain’(ciliary muscle is straining to maintain accommodation) ‘Watering’, ‘redness’ Headaches in the later part of the day Young children with significant hyperopia can develop a convergent squint Visual acuity at near tends to blur Treatment: convex lenses, keratorefractive surgery
- 81. Astigmatism Parallel rays come to focus in two focal lines rather than at a single focal point. Causes: - irregular curvature of the cornea - lens abnormalities Clinical features: Blurred vision Distortion of vision Head tilting and turning Headache and eye pain Treatment: cylinder lenses with out without spherical lenses (concave or convex).
- 82. Presbyopia Physiological loss of accommodation in advancing age. Cause: - deposit of insoluble proteins in lens in advancing age, leading to progressive decrease in the elasticity of the lens, resulting in decrease accommodation. Clinical features: Difficulty reading fine print Visual fatigue Headache Treatment: convex lenses in near vision - Reading glasses - Bifocal glasses - Trifocal glasses - Progressive power glasses