Nice to read

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

4. External Features

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

8. Lacrimal Apparatus

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

17. Eyeball Structure

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

50. Congenital Glaucoma

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