Ophthalmology[Physiology + Pathology + Treatment of the Eye] Prepared by: Md. Hasif Sinha M.Pharm Product Executive (PMD) Email: email@example.com
What is Ophthalmology?• Ophthalmology is the branch of medicine that deals with the Anatomy, Physiology & Diseases of the Eye.• The word “Ophthalmology” comes from the Greek roots “Ophthalmos” meaning “Eye” & “Logos” meaning “Thought”; Ophthalmology literally means “the science of eyes”.• An ophthalmologist is a specialist in medical & surgical eye problems.
Human Eye• Eye is the organ of vision that detects light• Human eye can distinguish about 10 million colors• Nearly spherical structure with a diameter of approximately 22 – 27 mm
Human Eye Functions• Helps to watch sights & stops excessive light entering into eyes• Protects the eyeball from physical damage• Spreads & reduces evaporation of tear film thus keeping the eye moist• Blinking of the eyelids helps spread the tears evenly over the eye which prevents the eye drying out (Normal blinking rate: 15 times/minute)
Anatomy of Human Eye• Eyeball is covered with 3 layers: 1. Outer: Fibrous Layer (Sclera-Cornea) 2. Middle: Vascular Layer (Uvea: Choroid-Iris-Ciliary body) 3. Inner: Nervous Layer (Retina)
1. Outer: Fibrous LayerSclera:• It is an opaque, fibrous, protective outermost layer• It is soft connective tissue• Spherical shape of the eye is maintained by the pressure of the liquid inside• It provides attachment surfaces for eye muscles
1. Outer: Fibrous LayerCornea:• It is transparent, curved front of the eye which helps to coverage the light rays which enters the eye• 5 layers: (1) Corneal Epithelium (2) Bowman’s Layer (3) Corneal Stroma (4) Descemet’s Membrane (5) Corneal Endothelium
2. Middle: Vascular LayerChoroid:• Vascular layer lying between the retina & the sclera• Has a network of blood vessels to supply nutrients to the cells• Removes waste products• It is pigmented that makes the retina appears black• Preventing reflection of light within the eyeball
2. Middle: Vascular LayerIris:• Pigmented muscular structure consisting of an inner ring of circular muscle & an outer layer of radial muscle• Most visible part of the eye• Contains sphincter muscle, which contracts the pupil• Controls the amount of light entering the eye
2. Middle: Vascular LayerCiliary Body:• Lies behind the iris• Has suspensory ligaments that hold the lens in place• Secretes the aqueous humour• Contains ciliary muscles that enable the lens to change shape during accommodation (focusing)
3. Inner: Nervous LayerRetina:• A layer of sensory neurons which controls vision by relay neurons & sensory neurons• Retina contains photoreceptor cells (rods & cones)• Rod cells functions in less intense light & Cone cells functions in bright light
3. Inner: Nervous LayerRetina:• Retina has two points: (1) Yellow Spot (Fovea): A part of the retina that is directly opposite the pupil and contains only cone cells. It is responsible for good visual resolution and color vision. (2) Blind Spot (Optic disc): A spot where the bundle of sensory fibers form the optic nerve. It contains no light- sensitive receptors.
Eyelid Layers & Conjunctiva• Consist of transparent tissue & thin membrane that covers the outer surface of the eye• Begins at the outer edge of the cornea, covering the white/visible part of the sclera & lining the inside of the eyelids• Conjunctiva also secretes oils & mucous that moisten & lubricate the eye
Pupil• A hole located in the center of the iris where light is allowed to continue its passage• In bright light it is constricted & in dim light it is dilated
Fundus• Interior surface of the eye• Includes the retina, optic disc, macula, fovea & posterior pole• Can be seen with ophthalmoscope
Tear film• Tears are formed by tiny glands that surround the eye• Composed of 3 layers: (1) Lipid Layer (2) Aqueous Layer (3) Mucous Layer
Tear film(1) Lipid Layer:• It is the outermost layer• It is produced by the meibomian glands and acts as a hydrophobic barrier (water insoluble) that prevents tears from constantly leaving the eye and running down the cheeks
Tear film(2) Aqueous Layer:• It is the middle layer.• It is produced by the lacrimal gland and is composed of water, proteins, and other substances, such as lipocalin, lactoferrin, lysozyme, and lacritin.• The aqueous layer is responsible for the control of infectious agents and osmotic balance, as well as the even distribution of the tear film throughout the eye surface.
Tear film(3) Mucous Layer:• It is the innermost layer.• It is produced by goblet cells of the conjunctiva and acts as a hydrophilic layer (water soluble) that coats the cornea and helps to ensure the even distribution of the tear film throughout the eye surface.
Tear film (at a glance)Name Container(s) Secretors Functions coats the aqueous layer; provides a hydrophobic barrier that envelopes tears and meibomian Lipid prevents their spilling onto the cheek. These oils glands (or layer glands are found among the tarsal plates. Thus, tarsal glands) the tear fluid deposits between the eye proper and oil barriers of the lids. water and other substances such as promotes spreading of the tear film; promotesAqueous proteins (e.g., tear lacrimal gland the control of infectious agents; promotes layer lipocalin, lactoferrin, osmotic regulation lysozyme and lacritin) coats the cornea; provides a hydrophobic layer;Mucous Conjunctival mucin allows for even distribution of the tear film; layer goblet cells covers the cornea
Lens• Transparent, flexible & biconvex shaped• About 5mm thick & diameter is about 9 mm• Its curvature is controlled by ciliary muscles through the zonules• Helps to refract light to be focused on the retina to form an image
Optic Nerve• Optical Nerve is also called Cranial Nerve II• Transmits visual information from the retina to the brain• Contains 1.2 million nerve fibers• Damage of the optic nerve typically causes permanent loss of vision
Retinal Ganglion Cell• A type of neuron located near the inner surface of the retina of the eye• Receives visual information from photoreceptors via two types of intermediate neurons: (1) Bipolar cells (2) Amacrine cells• Retinal ganglion cells collectively transmit image-forming & non-image forming visual information from the retina to several regions in the thalamus, hypothalamus, & mesencephalon or midbrain
Extraocular AnatomyEyelids:• Protects the eyeball• Wipe the eye & prevent dehydration• Secretion, distribution & drainage of tears on the eyes which can fight in bacterial infectionEyelashes:• Prevents fine particles to entering the eye
Eye Muscles1. Extraocular Muscles:• Controls the movements of the human eye• Extraocular muscles 7 types: (1) Superior Rectus (2) Inferior Rectus (3) Lateral Rectus (4) Medial rectus (5) Superior Oblique (6) Inferior oblique (7) Levator palpebrae superioris
Eye Muscles2. Intraocular Muscles/Ciliary Muscles:• A ring of striated smooth muscle in the eyes middle layer (vascular layer) that controls accommodation for viewing objects at varying distances & regulates the flow of aqueous humour into Schlemms canal.• It changes the shape of the lens within the eye, not the size of the pupil which is carried out by the sphincter pupillae muscle.
Ciliary Body• Circumferential tissue inside the eye composed of the ciliary muscle and ciliary processes.• It is triangular in horizontal section & is coated by a double layer, the ciliary epithelium. This epithelium produces the aqueous humor.• The inner layer is transparent, covers the vitreous body & is continuous from the neural tissue of the retina.
Liquid Inside Eye• There are two types of humor inside the eye. They are: 1. Aqueous Humor 2. Vitreous Humor
Aqueous Humor• Thick watery fluid which fills the space between the lens & cornea• Maintains the intraocular pressure (IOP) & helps to maintain the shape of the anterior chamber of the eyeball• Provides nutrition for the ocular tissues, cornea, trabecular meshwork & lens• Carry away waste products from metabolism of the above ocular tissues
Schlemm’s Canal• A circulatory canal in the eye that collects aqueous humor from the anterior chamber & delivers it into the bloodstream via the anterior ciliary veins• Canal transfers approximately 2-3 microliters of aqueous humor/minute
Vitreous Humor• Transparent, colorless & jelly-like mass located behind the lens• Fills the space between the lens of the eye & the retina lining the back of the eye• Acts as a suspension for the lens so that the delicate lens is not damaged• Helps to maintain the shape of the eyeball• Maintains intraocular pressure (IOP)• Acts as refractive index
Vitreous Cavity• Contains the vitreous humor• Largest cavity of the eye, located behind the crystalline lens & almost completely surrounded by the retina
Intraocular Pressure• IOP is the fluid pressure inside the cell• Measured with a Tonometer• Normal IOP: 10 – 20 mmHg
Diseases of the EyeA. Disorders of Eyelid, Lacrimal system and Orbit: 1. Blepharitis 2. DacryocystitisB. Disorders of Conjunctiva: 1. Conjunctivitis (Allergic & Infective) 2. Blepharoconjunctivitis 3. Keratoconjunctivitis
Diseases of the EyeC. Disorders of Sclera, Cornea, Iris & Ciliary body: 1. Scleritis 2. Keratitis 3. Corneal ulcer/Corneal abrasion 4. Keratoconjunctivitis sicca (Xerophthalmia) 5. Iritis 6. UveitisD. Disorders of Lens: 1. Cataract
Diseases of the EyeE. Disorders of Choroid & Retina: 1. Age-related Macular Degeneration (AMD)F. Ocular Hypertension (OHT): 1. Glaucoma
Diseases of the EyeA. Disorders of Eyelid, Lacrimal system and Orbit: 1. Blepharitis:• Inflammation of eyelids & eyelashes• Causes itching, irritation & redness in the eyelids & white flaky skin near the eyelashes• Commonly associated with Staphylococcus bacteria i. Anterior Blepharitis:• Occurs at the outside front edge of the eyelid where the eyelashes are attached ii. Posterior Blepharitis/Meibomianitis:• Affects the inner edge of the eyelid that comes in contact with the eyeball
Diseases of the EyeA. Disorders of Eyelid, Lacrimal system and Orbit: 2. Dacryocystitis:• Inflammation of lacrimal sac• Causes pain, redness & swelling over the inner aspect of the lower eyelid• Often caused by nasolacrimal obstruction• Commonly associated with Staphylococcus & Pseudomonas species
Diseases of the EyeB. Disorders of Conjunctiva: 1. Conjunctivitis: Inflammation of the conjunctiva i. Allergic Conjunctivitis:• It is a response to an allergen (such as pollen)• It shows watery swelling or edema of the conjunctiva• Treatment includes antihistamins, mast cell stabilizers etc ii. Infective Conjunctivitis:• Occurs mainly due to bacteria & virus• Bacterial conjunctivitis produces thicker, yellow-green discharge• Viral conjunctivitis produces watery & mucous discharge• Infective conjunctivitis commonly associated with Neisseria gonorrhoeae, Streptococcus pyogenes, Staphylococcus aureus, Chlamydia, Moraxella
Diseases of the EyeB. Disorders of Conjunctiva: 2. Blepharoconjunctivitis:• Inflammation of conjunctiva & eyelid
Diseases of the EyeB. Disorders of Conjunctiva: 3. Keratoconjunctivitis:• Inflammation of conjunctiva & cornea
Diseases of the EyeC. Disorders of Sclera, Cornea, Iris & Ciliary body: 1. Scleritis:• Painful inflammation of the sclera
Diseases of the EyeC. Disorders of Sclera, Cornea, Iris & Ciliary body: 2. Keratitis:• Inflammation of the cornea• Eye turns red & may be sensitive to light• In severe cases, there can be strong pain, loss of vision & pus may form
Diseases of the EyeC. Disorders of Sclera, Cornea, Iris & Ciliary body: 3. Corneal ulcer/Corneal abrasion:• Loss of the surface epithelial layer of the cornea• Corneal ulceration begins with pain followed by increased tearing• Most corneal ulcers are caused by several infections: Bacterial infections: Caused by Staphylococcus aureus, Streptococcus viridans, Escherichia coli, Enterococci, Pseudomonas etc & treated by antibiotics (eg. Ciprofloxacin) Fungal infections: Caused by Aspergillus sp., Fusarlum sp., Candida sp. etc & treated by anti-fungal agent (eg. Clotrimazole) Viral infections: Caused by Herpes simplex, Herpes Zoster, Adenoviruses etc & treated by anti-viral agent (eg. Acylovir)
Diseases of the EyeC. Disorders of Sclera, Cornea, Iris & Ciliary body: 4. Keratoconjunctivitis sicca (Xerophthalmia):• Caused by decrease tear formation or increased tear film evaporation; resulting dry eye• Typical symptoms are dryness, burning & a sandy-gritty eye irritation
Diseases of the EyeC. Disorders of Sclera, Cornea, Iris & Ciliary body: 5. Iritis:• Inflammation of the iris
Diseases of the EyeC. Disorders of Sclera, Cornea, Iris & Ciliary body: 6. Uveitis:• Inflammatory process involving the interior of the eye (Iris, Ciliary body & Choroid)
Diseases of the EyeD. Disorders of Lens: 1. Cataract:• Cloudy lens inside the eye which leads to decrease vision• Caused by long-term ultraviolet exposure, exposure to radiation, secondary effects of diseases such as diabetes & advanced age• Treatment option is surgically remove the cloudy lens by intra ocular lens (IOL) implantation• If not treated vision loss & blindness occurs
Diseases of the EyeD. Disorders of Lens: 2. Myopia:• Commonly known as being nearsighted and shortsighted• It is a condition of the eye where the light that comes in does not directly focus on the retina but in front of it• Treatment option is surgically remove the cloudy lens by intra ocular lens (IOL) implantation
Diseases of the EyeE. Disorders of Choroid & Retina: 1. Age-related Macular Degeneration (AMD):• Photosensitive cell in the macula malfunction & over time cease to work
Diseases of the EyeF. Ocular Hypertension (OHT):• A condition when intraocular pressure being higher than normal• Most important risk factor for glaucoma 1. Glaucoma:• An increase in the pressure in the eyeball is usually termed as glaucoma (normal IOP: 12-20 mmHg). It is mainly due to: Excess aqueous humor formation, Impairment of drainage of aqueous humor out of the globe. It’s the leading cause of blindness.• There are 4 major types of glaucoma: (1) Open-angle (chronic) glaucoma (2) Angle-closure (acute) glaucoma (3) Congenital glaucoma (4) Secondary glaucoma.
Ocular Medications Topical Ocular Diagnostic DrugsFluorescein Dye:• water soluble orange-yellow dye• green under cobalt blue light - ophthalmoscope or slit lamp• stains damaged corneal and conjunctival and mucus epithelium and contact lensesAnesthetics:• e.g. proparacaine HCl 0.5%, tetracaine 0.5%• indications: removal of foreign body and sutures, tonometry, examination of painful cornea• toxic to corneal epithelium and can lead to corneal ulceration and scarring with prolonged use, therefore NEVER prescribe
Ocular Medications Topical Ocular Diagnostic DrugsMydriatics:• dilate pupils, cycloplegic• indications: refraction, ophthalmoscopy, therapy for iritis• cholinergic blocking (paralyze iris sphincter i.e. dilation and cycloplegia)• adrenergic stimulating (stimulate pupillary dilator muscles, no effect on accommodation, e.g. phenylephrine HCl 2.5% (duration: 30-40 minutes, usually used with tropicamide for additive effects, side effects: hypertension, tachycardia, arrhythmias) Mydriatic Drugs Duration of Action Tropicamide 0.5%, 1% 4-5 hours Cyclopentolate HCl 0.5%, 1% 3-6 hours Homatropine HBr 1%, 2% 3-7 days Atropine sulfate 0.5%, 1% 1-2 weeks Scopolamine HBr 0.25%, 5% 1-2 weeks
Ocular Medications Glucoma MedicationsBeta-Adrenergic Blockers:• decrease aqueous humour formation• nonselective beta-blockers (e.g. Timolol, Levobunolol, Metapranolol)• systemic side effects: bronchospasm, bradycardia, heart block, hypotension, impotence, depression, exacerbation of congestive heart failureCholinergic Stimulating:• increases aqueous outflow• e.g. pilocarpine, carbachol• side effects: miosis, decreased night vision, headache, increased GI motility, decreased heart rate
Ocular Medications Glucoma MedicationsAdrenergic Stimulating:• decrease aqueous production and increase flow• e.g. epinephrine HCl, dipivifrin (Propine), brimonidine (Alphagan)• side effects: contact allergy, hypotension in childrenCarbonic Anhydrase Inhibitor:• decrease aqueous production• e.g. oral acetazolamide (Diamox), topical dorzolamide• side effects: renal calculi, nausea, vomiting, diarrhea, weight loss, aplastic anemia,• bone marrow suppression, systemic acidosis• side effects generally absent with topical preparations
Ocular Medications Glucoma MedicationsProstaglandin Agonists:• improves uveoscleral outflow• e.g. latanoprost (Xalatan)• side effects: iris colour change, lash growth, trichiasis
Ocular Medications Topical Ocular Therapeutic DrugsDecongestants:• weak adrenergic stimulating drugs (vasoconstrictor)• e.g. naphazoline HCl 0.012%, phenylephrine HCl 0.12%, tetrahydrazaline 0.05%• rebound vasodilation with over use can exacerbate angle closure glaucomaCorticosteroids:• never prescribed by primary care physician unless emergency indications• Complications (potentiates herpes simplex keratitis and fungal keratitis as well as masking symptoms (within days), posterior subcapsular cataract (within months), increased IOP, more rapidly in steroid responders (within weeks)
Ocular Medications Topical Ocular Therapeutic DrugsAntibiotics:• indications: bacterial conjuntivitis, keratitis, or blepharitis• commonly as topical drops or ointments, may give systemically• e.g. sulfonamide (sodium sulfacetamide, sulfisoxazole), gentamicin, erythromycin, tetracycline, bacitracin, polymyxin
Ophthalmology Abbreviations 30-2 Commonly used automated Humphrey visual fields A/C or AC Anterior chamber ACG Angle closure glaucoma ALPC Argon laser photocoagulation (often for diabetic macular edema) ALT Argon laser trabeculoplasty (for glaucoma) AMD Age-related macular degeneration APD Afferent pupillary defect BCC Basal cell cancer BDR Background diabetic retinopathy BRVO Branch retinal vein occlusion c or cc With refractive correction C/D Cup-to-disc ratio of the optic nerve CF Count fingers visual acuity CL, HC Contact lenses, hardSCL, EWSCL Soft and extended wear
Ophthalmology Abbreviations CME Cystoid macular edema CRAO Central retinal artery occlusion CRVO Central retinal vein occlusionCSR or CSCRCentral serous chorioretinopathy CVFConfrontation visual field Cyl Cylinder (in refraction) DDiopter DCRDacryocystorhinostomy DVD Dissociated vertical deviation (a form of strabismus) DVSDuctions, versions, saccades DWSCL Daily wear contact lenses ECCE c IOLExtracapsular cataract extraction with intraocular lens implantation PSC Posterior subcapsular cataract EOG Electrooculogram ERG Electroretinogram
Ophthalmology Abbreviations EOM Extraocular muscle ERM Epi-retinal membraneET, E(T), E, E’ Esotropia, intermittent esotropia, esophoria and esophoria at near EUA Exam under anesthesia HM Hand motion vision ICCE Intracapsular cataract extraction IF 1% Inflamase Forte 1% IK Interstitial keratitis IO Inferior oblique IOL Intraocular lens IOP Intraocular pressure IR Inferior rectus K Cornea or Keratometer reading (measures the curvature of the cornea) KCS Keratoconjunctivitis sicca KP Keratitic precipitate
Ophthalmology AbbreviationsL HoT, R HoT Left Hypotropia, right hypotropia LHT, RHT Left hypertropia, right hypertropia LOC Laxative of choice LPI Laser peripeheral iridectomy LP, LPO Light perception, light perception only LR Lateral rectus M Manifest (non-cyclopleged) refraction M&N Mydriacyl & Neosynephrine mixture used for pupil dilation NLP No light perception NS or NSC Nuclear sclerotic cataract NVD Neovascularization of the disc NVE Neovascularization of the retina elsewhere (outside the disc) NVI Neovascularization of iris OD, OS, OU Right eye, left eye, both eyes OHT Ocular hypertension
Ophthalmology Abbreviations P1, P2, P4 Pilocarpine (with concentration) PC Posterior chamber or posterior capsule PD Prism dioptersPE, PHACO Phacoemulsification PEE Punctate epithelial erosions PEG Punctate epithelial granularity PEK Punctate epithelial keratitis or keratopathy PERL Pupils equal and reactive to light PF, PA 1% Pred Forte eye drops, prednisolone acetate PH Pinhole PI 1/8 Phospholine Iodine 1/8% PKP or PK Penetrating keratoplasty (cornea transplant) POAG Primary open angle glaucoma POHS Presumed ocular histoplasmosis syndrome PPDR Pre-proliferative diabetic retinopathy
Ophthalmology Abbreviations PRP Pan-retinal photocoagulation PSC Posterior subcapsular cataract PVD Posterior vitreous detachment RD Retinal detachment ROP Retinopathy of prematurity RP Retinitis pigmentosa RPE Retinal pigment epithelium S or SC Without refractive correction SLE or SLX Slit lamp exam SPK Superficial punctate keratitis (Thygeson or keratopathy) SR Superior rectusSRN, SRNVM Subretinal neovascular membrane Ta Applanation tonometry T ½, T ¼ Timoptic (with concentrations) Va Visual acuity
Ophthalmology Abbreviations VF Visual field Vit Vitreous VTX Vitrectomy W4D Worth 4-dot test (in strabismus)XT, X(T) Exotropia, intermittent exotropia X, X’ exophoria, exophoria at near YAG Neodymium-yttrium aluminum garnet laser Δ Prism diopter
Why we should use preservative free drugs?• Preservative free eye drops are the eye drops with no chemical preservative.• Most of the eye drops consist of chemical preservatives to hinder the microbial growth and also always keep them free of bacterial contamination. However these chemical preservatives may possibly cause allergic reaction or hypersensitivity to some of the individuals. Therefore always remember, eye drops that contain chemical preservatives can normally result in itchiness, redness and even dryness of eye. That’s why most of the eye care professionals suggest applying preservative free eye drops to prevent this issue.• Most preservative free allergy eye drops can be found in tubes of single unit dose. They must be disposed of right after 24 hours once they are opened. If these eye drops are exposed to the environment and stored too long, it will cause bacteria to grow in the solution.