Introduction to
OPHTHALMOLOGY DR. NORASYIKIN MUSTAFA MBBCH (DUBL), M.OPHTHAL (UM)
First…. Make sure you know how to spell
Oph thal mo
lo
Ophthalmos (Greek) = eye
gy
What is the difference?
Ophthalmology
vs
Optometry
Ophthalmologist
vs
Optometrist
Optician
ANATOMY & PHYSIOLOGY OF THE EYE … LAYER BY LAYER
Components Accessory
structures
Posterior segment
Eyelids
Sclera
Lacrimal system
Choroid
Retina
Macula
Optic disc
Vitreous
Anterior
segment
Conjunctiva
Cornea
Anterior chamber
Iris/pupil
LR, MR, SR, IF, SO, IO
Lens/suspensory ligaments
LPS
Ciliary body
Extraocular muscles
Suspensory ligaments
Posterior chamber
Sclera Choroid Retina
Lens
Fovea Conjunctiva Cornea Optic nerve
Anterior chamber Pupil Iris Ciliary body Vitreous body
EYELIDS
2 main functions
1. Protection of the eyeball
2. Secretion, distribution and drainage of tears
Consists of
Skin (no subcutaneous fat)
Muscle (orbicularis oculi, levator palpebral superioris)
Tarsal plate – dense fibrous tissue
Palpebral conjunctiva
Glands
Eyelashes
Blood supply
Anastomosis between branches of ECA and ICA
Sensory innervation: Trigeminal nerve
Upper eyelid: V1 (ophthalmic)
Lower eyelid: V2 (maxillary)
Lymphatics
Preauricular and submandibular LN
EYELIDS
Two muscles are responsible for eyelid movement
1. Orbicularis oculi
closes the eye, 7th CN (facial)
2. Levator palpebral superioris
opens the eye, 3rd CN (oculomotor nv)
*
Mueller’s muscle
On deep surface of LPS
A smooth muscle supplied by sympathetic innervation
Opens the eye
Facial nerve palsy (e.g. in stroke) will result in inability to close the eye fully (lagophtalmos)
Horner’s syndrome (partial ptosis) vs Thyroid eye disease (lid retraction)
Open the eye = 3rd (Oculomotor)
Close the eye = 7th (Facial)
Oculomotor nerve (3rd CN) opens the eye like a pillar
www.timroot.com
Facial nerve (7th CN) closes the eye like a fish-hook
Meibomian glands
Meibomian glands Healthy
Unhealthy
CONJUNCTIVA
Is a semi-transparent mucous membrane lining the eyelids and covering the anterior eyeball up to the edge of the cornea.
Function
Protects the globe
Produces tear film
Can be divided into 3 parts
1. Bulbar
2. Fornix
3. Palpebral
1. Bulbar conjunctiva
2. Palpebral conjunctiva
3. Conjunctiva fornices
CONJUNCTIVA DOES NOT LINE THE CORNEA!
Inflammed conjunctiva ‘the eye is injected’
Chemosis
Normal conjunctiva ‘the eye is white’
Fine superficial conjunctival vessels
Severe chemosis
Pale conjunctiva
CORNEA
Is transparent
Main structure responsible for the refraction of light entering the eye
Avascular
Nourished by aqueous humour and capillaries at its edge
Nerve supply: Ophthalmic division of Trigeminal nerve (V1)
Cornea
Has 5 distinct layers
Thickness: 500-600um
Epithelium – stratified squamous epithelium Bowman’s membrane – transparent, composed of collagen. Nonregenerating layer. Healed by scarring. Stroma – water, collagen and keratocytes. Regular array. Fairly dehydrated to maintain clarity Descemet’s membrane – can regenerate Endothelium – monolayer. Endothelial pump draws water out from the stroma to maintain corneal clarity. Does not regenerate.
Cornea
Refraction of light occurs because of the curved shape of the cornea and its greater refractive index compared with air
(Air n=1.0, cornea n=1.33)
The cornea is tranparent because of the specialised arrangement of the collagen fibrils within the stroma, which must be kept in a state of relative dehydration.
Corneal oedema
Corneal scar
TEAR FILM
Layer of fluid on the surface of cornea
Also called precorneal tear film
Is a trilaminar structure
TEAR FILM Component
Produced by
1. Mucin layer
Goblet cells of the conjunctiva
2. Aqueous layer
Lacrimal gland
3. Lipid/oily layer
Meibomian glands of the eyelids
ANTERIOR and POSTERIOR CHAMBERs Anterior Chamber
Posterior Chamber
Boundary:
Anterior: Iris
Anterior: Cornea
Posterior: Lens and zonules
Posterior: Iris and part of anterior surface of lens
Periphery: Ciliary body
Periphery: iridocorneal angle
Filled with aqueous humour (clear fluid)
Cornea 1. Trabecular pathway (Conventional pathway)
Iridocorneal angle
ANTERIOR CHAMBER 1
Schlemm’s canal Trabecular meshwork
2
2. Uveoscleral pathway (Unconventional pathway) ≈15% (varies with age)
Iris Ciliary body
Lens POSTERIOR CHAMBER
IRIS AND PUPIL
Iris is connective tissue containing muscle fibres, blood vessels and pigments
Function: to control light entry to the retina and to reduce intraocular light scattering
Has 2 types of muscles:
1. Radial muscle / dilator pupillae
2. Circular muscle /sphincter pupillae
Pupil dilatation is caused by contraction of dilator pupillae (Sympathetic nervous system)
Pupil constriction is caused by contraction of constrictor muscle (Parasympathetic nervous system)
Pupil constricts (miosis)
Pupil dilates (mydriasis)
CILIARY BODY
Part of the uveal tract
Is a specialised structure uniting the iris and the choroid
Functions:
Produces aqueous humour
Involves in accommodation. It anchors the lens via the zonules, through which it modulates lens convexity.
Controlled by parasympathetic nervous system (oculomotor nerve)
CRYSTALLINE LENS
Biconvex, transparent, avascular structure
Highest protein content in the body
Held in place by suspensory ligaments
Consists of:
Capsule (anterior/posterior)
Cortex
Nucleus
ACCOMMODATION ď ľ
A reflex action of the eye, in response to focusing on a near object, then looking at a distant object and vice versa. Vergence
Pupils dilate
Change in lens shape
Pupils constrict
Change in pupil size
POSTERIOR SEGMENT
Choroid
Retina
Macula
Vitreous
Optic Nerve
3 COATINGS OF THE EYE
Sclera
Choroid
Retina
SCLERA
Fibrous coat of the eyeball
Cornea and sclera merge at the limbus
Mainly collagenous
Avascular apart from some vessels on its surface
Acellular
CHOROID
Part of the uveal tract
Thin brown tissue
Highly vascularied
Provides nutrients and oxygen to the retina
The choroid is opaque making sure no light is scattered from the sclera to the retina.
CHOROID UVEAL UVEAL TRACT TRACT
=
IRIS IRIS
CILIARY + CHOROID + CILIARY CHOROID BODY BODY
Iris
Iritis
Ciliary body
Intermediate uveitis
Iris + Ciliary body
ANTERIOR uveitis
Choroid
Choroiditis / POSTERIOR uveitis
Iris + CB + choroid
PAN uveitis
RETINA
Thin, semitransparent, multilayered sheet of neural tissue
Lines the inner aspect of the posterior 2/3 of the globe
Consists of 10 layers
RETINA
Choroid Retinal Pigment Epithelium
PHOTORECEPTORS
ď ľ
Cones concentrated at the macula. Fine vision (acuity) and colour appreciation
ď ľ
Rods are mainly at peripheral. Vision in low light levels and for detection of movement
Posterior pole ď ľ
Area of the retina bound by superior and inferior arcades to include both macula and optic disc.
Macula
Centre of the posterior macula
Responsible for fine central vision
Has yellow pigment (xanthophyll)
Accumulation of extracellular material can cause macula thickening
VITREOUS
Clear, avascular, gelatinous body
Comprises 2/3 of the volume of the eye
99% water, 1% hyaluronic acid and collagen
The vitreous is adherent to the retina at certain points mainly at the optic disc and at the ora serrata.
Posterior vitreous detachment is common to cause floaters.
OPTIC NERVE
2nd cranial nerve
The ganglion cell axons make a right-angled turn into the optic nerve at the optic disc.
There is no photoreceptor at the optic disc, thus corresponds to the physiological blind spot
OPTIC DISC
Lacrimal system
Greek: dakryon (tear), cysta (sac), adenas (gland), -itis (inflammation )
Tear Production:
Lacrimal gland – located in the lacrimal fossa in the superotemporal part of the orbit. Produces reflex secretion in response to irritation or emotion
Tear Drainage
Lacrimal punctum (one on each eyelid)
Canaliculi
Lacrimal sac
Nasolacrimal duct
HISTORY TAKING
History
Presenting Complaint (PC)
Hx of PC
Past Ocular Hx (POH)
PMHx/PSHx
Meds
Allergy
Social Hx
Summary
PC in Ophthalmology
Blurring of vision
Foreign body sensation
Lost of vision
Eye swelling
Eye pain
Drooping of eyelid
Eye redness
Tearing
Headache
Eye discharge
Nausea/Vomiting
Floaters
Flashes of light
Distortion of image/ metamorphopsia
Photophobia
POH
FHx
Eye trauma
FHx
Eye surgery
Eye disease
Any eye procedures
Eye blindness
Glasses use. Myopia/hyperopia/presbyopia
THANK YOU