THE CORNEA By EMAD M ELHADY MD PROF

THE CORNEA By EMAD M. ELHADY MD PROF. OF OPHTHALMOLOGY FACULTY OF MEDICINE ZAKKAZEEKK UNIVERSITY

THE CORNEA GROSS ANATOMY Anterior 1/6 of outer coat Curved & Domshaped Fibrous, Transparent & No BVs Diameter : Horizontal 12 mm Vertical 11 mm Thickness: Central 0. 5 - 0. 6 mm Peripheral 0. 8 – 1. 0 mm Radius of Curvature : Anterior 8 mm Posterior 7 mm Refractive Index : 1. 37 ? Refractive Power : 42 D ( what is Diopeter? ) ( What is The LIMBUS ? )

MINUTE ANATOMY 5 LAYERS (1) Epithelium St. Squamous Nonkeratinised (5 -6 layers) Surface Flat cells (2 -3 layers) Intermed. Polyhedral cells (2 -3 layers) Basal Columnar cells (one layer) (2) Bowman’s layer Structure less (Acellular) condensation Never regenerate Ends as a round border

(3) THE STROMA (Substantia Propria) - 90% of corneal thickness - C T Bundles ( Regular arrangement ) - Bundles of each layer \ to each other perpendicular to next layer - Cells ( present in Lacunae ) Corneal corpuscles ( Keratoblasts ) Corneal metabolism & Healing Leucocytes Inflammation (4) DESCEMET’S MEMBRANE Homogenous, Structureless & Highly Elastic Resistant & Easily Regenerate

CORNEAL ENDOTHELIUM One Layer of Polyhedral cells Partial dehydration of the cornea Continuous with the Endothelium of T M NERVE SUPPLY OF THE CORNEA 5 TH C. N OPHTH. division CILIARY N NASOCILIARY N PAIN & COLD & SUPERFICIAL TOUCH 2 Long

CORNEAL PHYSIOLOGY NUTRITION ( cornea is avascular ) By diffusion Tear Film Aqueous humour Limbal capillaries CORNEAL TRANSPARENCY ( WHY ? ) Anatomical Factors : Cornea is avascular Epithelium is nonkeratinized Stromal lamellae are regular Nerves are nonmyelinated Precorneal tear film Physiological Factors : Corneal dehydration Uniform refractive indices of corneal tissue FUNCTIONS OF THE CORNEA Refractive 42 D Protective ( corneal reflex )

THE LIMBUS ( The Corneo-Scleral Junction ) n Corneal epithelium Conjuctival epithelium n Bowman’s membrane ends as a rounded border n Substantia propria n Descemet’s membrane n Endothelium Sclera (irregular lamellae) Trabecular meshwork Endothelium of the angle of AC

KERATITIS KERATOS i. Ti. S CORNEA INFLAMMATION SUPERFICIAL KERATITIS Suppurative (Corneal Ulcer) Non. Suppurative (Pannus) INTERSTITIAL KERATITIS Suppurative (Central Abscess) Local) DEEP KERATITIS Non. Suppurative (Diffuse or Suppurative (Post Abscess or

SUPPURATIVE SUPERFICIAL KERATITS (CORNEAL ULCERS) DEFINITION Localized Necrosis of Sup. Stroma with destruction of overlying Epith. ETIOLOGY Predisposing Factors Precipitating Factors Causative Organisms

Predisposing Factors Local a) Trauma - Abrasion ( Gono & Diph can invade normal epithelium ) - FB , Rubbing lashes , PTDs , CL b) Loss of corneal sensations c) Ocular causes ( xerosis, A deficiency, Lagoph. ) d) Prolonged use of Steroids General malnutrition Diabetes Pregnancy Liver & Renal Failure

PRECIPITATING FACTORS Infection of nearby structures CAUSATIVE ORGANISMS a) Bacterial e. g. Gono, Diphth. , Pneumo, Staph, Strept…. b) Fungal ( not common ) c) Viral e. g. Herpes Simplex and Zoster d) Acanthamoeba (C. L. )

PATHOLOGY OF CORNEAL ULCERS Stage of Infiltration Inflammatory reaction PNLs Grey disc shaped area - Oedema - Ciliary injection Stage of ulceration A) Progressive unclean Stage Necrotic area ulcer with irregular Edge Necrotic Floor Surrounded by Dense reaction B) Regressive Clean Stage Large ulcer with regular Edge Deep, Clear, Transparent Floor Less infiltration

Stage of Healing A) Vascularization Limbal cap. Sup. Vasc. AB & Fibroblasts B) Fibrous tissue formation NB : Epith. B. M. Mitosis & Migration Never regenerate Stroma D. M. Endothelium Irregular F. T. Permanent scar Nebula or Leucoma Regenerates as an elastic membrane Enlargement and Widening of cells

CLINICAL PICTURE Symptoms Pain Severe ( FB or pricking sensation ) Irritation of nerve endings Photophobia Lacrimation Blepharospasm Diminution of vision Signs Lids: Oedema Conj. : Ciliary injection Cornea: Loss of luster, Grey infilt. , Oedema & +ve FT Iris: Tender CB, Const. pupil & Aqueous flare

COMPLICATIONS OF CORNEAL ULCERS A) Non Perforated corneal ulcer Early Complications (1) 2 ry Iridocyclitis : ( Toxins ) (2) 2 ry Glaucoma : Open angle glaucoma (3) Descematocele : Small translucent bleb Not seen in children or T hypopyon ulcer Late Complications (Healing abnormalities) (1) Corneal opacity ( Nebula, Macula or Leucoma non adherent ) (2) Corneal Facet : rapid healing of the epith. (3) Keratectasia : ( weak corneal scar & (4) Pseudoptregium IOP )

B) COMP. OF PERFORATED CORNEAL ULCERS Early Complications (1) Iris Prolapse ( Big Para central or periph. Perforation ) (2) Anterior synechia ( Small periph. Perforation) (3) Corneal Fistula ( Small central perforation ) Lost AC IOP River Green Sign (4) Malposition of the Lens Sublaxation Ant. Dislocation Extrusion (5) Intra-ocular Hge Hyphema Vit. , Ret. And choroidal hges (6) Macular and Optic Disc Oedema (7) Endo or Panophthalmitis

B) COMP. OF PERFORATED CORNEAL ULCERS (cont. ) Late complications (1) Ant. Polar Cataract (Toxins ) (2) Leucoma Adherent ( Large Peripheral Perforation ) - AC irregular - Pupil pear shaped - IOP may be high - may be pigmented (3) Ant. Staphyloma ( partial or total ) (4) 2 ry Glaucoma (closed angle by PAS ) (5) Atrophia bulbi ( atrophy of the cil. processes )

MANAGEMENT OF CORNEAL ULCERS INVESTIGATIONS + TREATMENT A) Corneal Scrapping ( Culture & Sensitivity ) Gram Stain for Bacteria Geimsa Stain for Trachoma & Acanthamoeba Silver Stain for Fungi B) Local ttt (1) Atropine sulphate 1% (3) Bandage or Dark Glasses (4) Counter irritant (2) Dressings ( Antibiotic dps & oint ) C) Systemic ttt Antibiotics Vitamins A & C Analgesics

D) Treatment of Complications (1) 2 ry Glaucoma Usual ttt Antiglaucoma ttt paracentesis (2) Descematocele Bilateral Bandage or C L Avoid Straining Antiglaucoma ttt Hood Flap PKP (3) Perforation Small Large Cyanoacrylate. Tissue Adhesive Hood Flap or PKP

E) Treatment of Corneal Opacity Central Nebula Glasses or CL Eximer Laser Lamellar KP Leucoma PKP In blind eye CCL Tattoo Treatment of Resistant CU Scrapping for Culture & Sensitivity Debridement Cautery Chemical Physical S. C. injection of AB Conjunctivoplasty Therapeutic KP (Lamellar or Penetrating)

CORNEAL ULCERS Primary Corneal Ulcers - Infected Corneal ulcer Hypopyon Ulcers (Bacterial) Herpetic Ulcers (Viral) Mycotic Ulcers (Fungal) Acanthamoeba K (Protozoa) - Non-Infected Corneal ulcer Mooren’s Ulcer Keratomalacia Atheromatous Ulcer with Lagophthalmos Neuroparalytic Ulcer Traumatic Ulcer Secondary Corneal Ulcers

HYPOPYON ULCER Predisposing Factors Causative Agents: Pneumococci ( 80% ) Typical HU Morax Axenfield Bacillus (10%) Streptococci, Staphylococci, Pseudomonas and Fungi Clinical Picture Symptoms Pain Photophobia Lacrimation Blepharospasm Poor vision

Signs ( Acute Serpiginous ulcer ) - Haziness of the cornea ( loss of luster ) - Ciliary injection - Ulcer Near the centre Central advancing Edge Crescentic, undermined, preceded by dense infiltration Peripheral Healing Edge Flat, Epithelialized, Vascularized - Posterior Abscess : Dense infiltration in front of D M - Flourescein Test is +ve - Hypopyon in the Anterior Chamber ( Steril Pus ) PNL +Fibrin +Iris Pigment NB Perforation is common…why? Desematocele is Rare

Treatment of Hypopyon Ulcer n n n Treatment of the cause ( Dacryocystectomy) Usual ttt of corneal ulcer ABCD Subconjunctival Injection of AB Cephazoline ( 100 mg in 0. 5 ml ) Tobramycin or Amikacine ( 20 mg in o. 5 ml ) n Fortified Eye Drops Gentamycine or Tobramycine 15 mg/ml. n Treatment of 2 ry Glaucoma

Atypical Hypopyon Ulcer Pyogenic organisms other than Pneumococci (20%) Common in children with increased resistance The Ulcer : Anywhere in the cornea Not Serpiginous, spreads in all directions Perforation is less common Desematocele may occur

Fungal Ulcer Predisposing Factors Trauma with green plant Use of Steroids Contact Lenses Causative Agent Fusarium ( Filamentary fungi ) Candida ( Yeast forming fungi ) Aspergillus Clinical Picture Little or no ciliary Injection Raised, dry, grey white lesion with feathery margins Satellite lesions Stromal deep infiltrate Endothelial plaques Hypopyon

Treatment n n Usual ttt Topical Antifungal ttt Natamycine 5% Miconazole 1% Amphotericin B o. 3% Systemic Antifungal ttt Ketoconazole 400 mg/day Fluconazole 400 mg/day ( In cases of deep Keratitis or failure of topical ttt ) Surgical ttt (PKP)

Acanthamoeba keratitis n n n Aetiology Protozoa ( Tap water and Swimming pools ) 70% of cases are C L wearers Clinical Picture Punctate or Dendritic K Superficial Stromal K Partial or Complete ring of Infiltration Limbitis and Scleritis Treatment Debridment Topical ttt Diamidines (Propamidine) Biguanides (Chlorohexidine 0. 02%) Aminoglycosides (Neomycin) Antifungal (Miconazole and Ketoconazole)

Dendritic Corneal Ulcer Herpes Simplex Virus ( Epitheliotropic ) 1 ry infection in early childhood Dormant in 5 th Ganglion Recurrence with body resistance Predisposing factors Fevers (Influenza, Common cold and Pneumonia) Menstruation Drugs ( Immunosuppressive drugs or Steroids) Clinical Picture 1 ry Ocular infection Dermato-blepharitis Follicular Conjunctivitis Epithelia Keratitis

Recurrent Ocular Infection (C/P of H. Keratitis) (A) Blepharoconjunctivitis (as 1 ry infection) (B) Epithelial Keratitis Symptoms : as those of corneal ulcer Signs : A) SPK B) (Characters of Dendretic Herpetic Corneal Ulcer) Dendritic appearance Long course with tendency to Recurrence Superficial ( never perforate except in … ) Never Vascularised Hypothesia Double Stain Test C) Amoeboid Ulcer due to immunity or local Steroids

C) Stromal Keratitis (cell mediated immune reaction) n n n Interstitial Keratitis (unifocal or multifocal) Disciform Keratitis (stromal inf. and epithelial odema +kps) Necrotizing Keratitis Severe and rapidly progressive Overlying ulceration eccentric to infiltration -ve double stain Vascularisations D) Herpetic Iridocyclitis Complications drugs) Toxic punctate epithelial erosions (Antiviral

Treatment of Herpetic Epithelial Keratitis Local Antiviral Drugs Acyclovir ( Zovirax ) 3% eye ointment 5 times/day TFT ( Tri-Fluro-Thimidine ) eye drops Ara-A ( Vidarabine ) eye ointment IDU ( Iodo-deoxy-uridine ) eye drops NB Corticosteroids are contraindicated Treatment of Stromal H Keratitis Topical Corticosteroids Prophylactic Antiviral drugs Treatment of resistant cases Debridement ( to remove infected cells ) Cautery by Tinct. Iodine 7% in alcohol (kill the virus) Therapeutic L K

Herpes Zoster Ophthalmicus Varicella-Zoster Virus Neurotropic Virus Old age Immunity Clinical Picture : Lids : Dermatoblepharitis ( pain and rash ) Keratitis : ( Hutchinson’s rule ) Epithelial Keratitis ( Punctate or dendritic ) Interstitial Keratitis Scleritis Iris : 2 ry iridocyclitis IOP : 2 ry glaucoma Choroid : Focal choroiditis

Clinical Picture of H Z Ophthalmicus Retina : retinal vasculitis, detachment and necrosis Optic Nerve: Papillitis or Retrobulbar neuritis Orbit : Orbital oedema and Proptosis EOM : Paralytic Squint (3 rd N. palsy) Treatment: Acyclovir tab. 800 mg 5 times/ day for 7 days Steroids + Antibiotic skin oint. Steroids + Antibiotic eye drops Analgesics

Ulcer with Lagophthalmos A primary ulcer in the lower 1/3 of the cornea Bell’s phenomena n Symptoms as usual corneal ulcer ( of vision is not marked. . why? ) n n Signs Incomplete lid closure Ciliary injection & +ve flurorescein Ulcer in lower 1/3 with straight upper border n Treatment Usual ttt Methyl cellulose drops 0. 5% several times/day ttt of the cause

Keratomalacia n Non infective ulceration and melting of the cornea Vitamin A (malnourished infants or malabsorption in adults) n Clinical Picture Loss of corneal luster Appearance of yellow dots (deg. Epithelium) Melting of the cornea No inflammatory reaction (quite eye) Corneal hypothesia Conjunctiva: dry with Bitot’s spots 2 ry infection Endophthalmitis n Treatment Vit. A injection (200, 000 IU/day) ttt of hypoproteinemia ( fresh plasma) Topical vit. A in early cases Surgical ttt in late cases : Conj. Flap Therapeutic CL PK

Neurotrophic (Neuroparalytic) Keratitis Corneal Sensation Aetiology Herpes Zoster Radical ttt of 5 th Neuralgia ( Alcohol inj. ) Damage of Orbital Ns (SOF & OA syndromes) Clinical Picture Symptoms Signs No pain vision (central ulcer) Epithelial exfoliation starts at the center Large deep ulcer perforation Treatment Usual ttt of corneal ulcer Long term Bandage Tarsorraphy ( median )

Traumatic Corneal ulcer Trauma + 2 ry Infection Trauma External: wounds, chemicals, burn & FB Local: Lash, PTD & PTC Treatment Usual ttt + ttt of the cause

Mooren’s Ulcer ( chronic serpeginous ulcer ) 1 ry non infective corneal ulcer Rare Common in old age Aetiology ( unknown ) Limbal vasculitis Autoimmune disease Symptoms Signs Proteolytic enzymes necrosis of sup. layers 12345 Marginal grey infiltration Crescentic Ulcer Advanced edge ( undermined and creeps toward the center ) Healed edge ( Peripheral and vascularised ) Thin cornea Extension is slow and perforation is rare Treatment Usual ttt + Topical Steroids Topical Cyclosporine Conj. Excision // to the ulcer Lamellar keratoplasty Systemic Steroids & Immunosuppressive drugs

Atheromatous Corneal Ulcer Occurs on top of an old Leucoma Hyaline degeneration with desquamation and 2 ry infection Resistant with bad healing Commonly perforates due to 2 ry infection Treatment Usual ttt Conjunctival flap Keratoplasty

Secondary Corneal Ulcers n Ulcers 2 ry to MPC Marginal, Crescentic and Superficial ( Rare ) Rapid healing n Ulcers 2 ry to Gonococcal Conjunctivitis Marginal ulcer : Most common Ring ulcer : Multiple marginal ulcers Central and paracentral ulcers : usually perforate n Trachomatous Ulcers A) Typical Shape Horizontal Site In front of pannus Superficial Secondary infection is common Scarred by facet ( Healing ) B) Marginal, Central and Paracentral: not related to Pannus

2 ry Corneal Ulcers n Phlyctenular Ulcers A) Limbal ulcer: ( ulcer of limbal phlycten ) Deep, when perforate peripheral Leucoma Adherent B) Ring ulcer: multiple phylectens C) Fascicular ulcer: Superficial Starts near the limbus Creeps to the center followed by leash of B. V.

INTERSTITIAL KERATITIS Non Suppurative iflammation of the Stroma + Uveitis Aetiology Delayed hypersensitivity to infectious organism - Syphilis, T. B. , Leprosy - Herpes Simplex and Zoster, Measles and EBV (infectious M. ) Types (1) Diffuse I. K. (2) Dsciform Keratitis

Syphilitic Interstitial Keratitis n Congenital Syphilis ( 95% ) 5 – 15 Years Bilateral Hutchinson’s triad ( I. K. , Hutchinson’s teeth and Deafness ) n Acquired Syphilis ( 5% ) 10 years after 1 ry infection Unilateral Uveitis and Retinitis Symptoms Pain, photophobia, lacrimation, redness and vision

Signs of Syphilitic I. K. ( 1 ) Progressive Stage ( 2 weeks ) Severe infiltration ( haze ) + Vascularization Salmon patches ( reddish pink ) Ciliary injection ( 2 ) Florid stage ( 2 months ) Marked symptoms and signs vision up to HM ( 3 ) Regressive stage ( 2 years ) Residual interstitial corneal opacity Obliterated BV fine opaque lines Uveitis Investigations +ve Wassermann reaction

Treatment of Syphilitic I. K. - Antisyphilitic ttt ( Penicillin ) Atropine Steroids Keratoplasty for residual opacity DISCIFORM KERATITIS Antigen antibody reaction ( viral antigen ) H. S. & H. Z. Grey disc-shaped dense opacity Loss of corneal sensation Drop of vision Treatment Corticosteroids + Antiviral drugs Tarsorraphy

Keratitis profunda Localised non suppurative deep Keratitis Aetiology Allergic reaction to chronic infections e. g. TB Herpes Simplex or Zoster Trauma Idiopathic Clinical Picture Diffuse deep Keratitis Iridocyclitis Posterior Abscess and Ulcer Diffuse suppurative deep Keratitis Congenital, HU, Trauma, IK and endogenous with TB and S.

Degenerative Conditions ARCUS SENELIS Bilateral peripheral Fatty degeneration Common in old age Symptoms non Signs Arc shaped opacity in the upper ½ of cornea then lower ½ Clear zone between the opacity and Limbus (Lucid interval of vogt) Outer border is sharp and well defined Inner border is diffuse and illdefined NB ARCUS JUVENILIS may occur in hyperlipidemia or juv. DM

Band Shaped keratopathy Horizonal opacity ( in the interpalpebral area ) Old degenerated eyes Hyaline degeneration + Ca deposition

KERATOCONUS n Definition Progressive conical protrusion of the cornea Starts at Puberty Weakness of central part n Incidence Females _ Atopy Bilateral +ve family history n Symptoms Gradual of vision - Myopia ( Curvature & Axial ) - irregular Astigmatism - Opacity at the apex of the cone Sudden rupture of DM) of vision (Acute Hydrops i. e. acute edema due to

Signs of Keratoconus n A) Early Retinoscopy ( RR is spinning or scissoring ) placido disc: ring distortion Keratometer B) Late - Cone shaped central cornea seen by Profile view Notching of the L. L. on looking down Manson’ Slit Lamp Thin apex and deep A. C. - Deep opacity at the apex of the cone Rupture of BM Folds of DM - Fleisher ring: brown ring the cone base ( hemosidren deposition ) DD Ant. Staph. - Keratectasia - Keratoglobus Treatment - Early casrs : Glasses or hard CL Corneal Collagen Cross linking with Riboflavin - Late cases : PKP

KERATOGLOBUS Congenital enlargement of the Anterior Segment Signs Cornea: Large in diameter and curvature AC : Deep Iris : Tremulous Lens : Sublaxation Refraction: Stationary myopia DD : Buphthalmos Treatment: Glasses

n n KERATOPLASTY Aim: Replacing the opaque part by a clear cadaveric cornea Types: - Lamellar ( Superficial ) - Deep ( Penetrating ) NB: Both of them may be partial or total - Tectonic : Has a specific shape according to site and indication n Indications: - Optical a) Central corneal opacities b) Keratoconus - Therapeutic a) Resistant corneal ulcer b) Corneal fistula