Cornea Flashcards
What is the refracting power of the cornea?
40-44D ~2/3rd refracting power of the eye
Ehlers-Danlos Syndrome
- Features? Characteristics?
- 6 Major forms?
- Ocular findings
- Systemic findings?

- Systemic collagen disorder
- Features
- Hyperextensible joints
- skeletal abnormalities
- Blue sclera
- Mottled teeth
- Neurosensory deafness
- 6 major forms
-
Type VI (Kyphoscoliosis) - most ocular involvement ***
- AR deficiency in enzyme responsible for collagen stability & strength
-
Ocular findings
- Scleral fragility
- Risk of globe rupture
- KCN
- Retinal detachment
- Glaucoma
-
Systemic findings
- Muscle hypotonia
- Joint laxity
- Kyphoscoliosis & other skeletal changes
- Abnormal skin
-
Type VI (Kyphoscoliosis) - most ocular involvement ***
Band Keratopathy
- What does it look like?
- Causes?
- Symptoms?
- Treatment?
- Interpalpebral deposition of calcium phosphate salts in bowman’s membrane
- Begins peripherally & moves centrally
- 3 & 9
- Starts grey, becomes chalky white
- Clear intervening zone between peripheral edges & limbus
-
Swiss cheese pattern
- Represent corneal nerves that penetrate Bowman’s layer
- Late stage progresses anteriorly through epithelium
-
Causes
- DES
- Chronic exposure
- Chronic inflammation
- Uveitis
- Pthisis bulbi
- Interstitial keratitis
- Long-standing glaucoma
- Repeated trauma
-
Underlying systemic disease
- Hyperparathyroidism
- Vitamin D toxicity
- Sarcoidosis
- Paget’s disease
- Multiple myeloma
- Metastatic cancer to bone
- Norrie’s disease
-
Symptoms
- Asymptomatic
- Decreased VA
- Pain
- FBS
- Epithelial erosions
-
Treatment
-
Lubrication
- Drops
- Drops Gels
- Ointments
- BCL
- RGP/Scleral lenses for induced astigmatism correction
- Chelation with EDTA & superficial keratectomy (corneal scraping)
- PTK
- Reserved for recurrent or advanced cases
-
Lubrication

Disciform endotheliitis

- Most common presentation
-
Symptoms
- photophobia
- Mild to moderate discomfort
- Decreased vision possible
- Many cases self-limited
-
Presentation
- Limbal injection
- Round area of stromal edema
- Central paracentral
- Entire thickness of stroma involved
- Overlying microcystic edema to bullae formation
- Iritis
- Elevated IOP
- Responds well to tx
Lattice dystrophy
- Characteristics?
- Symptoms?
- Treatment?

- AD inheritance
- TGFB1 gene mutation
- Presents 1st decade
- Primary, localized corneal amyloidosis
- Begins with development of refractile lines in anterior stroma which progressives to stromal opacification
-
Symptoms
- Blurred vision
- Corneal erosions
-
Treatment
- Bandage CL
- PK
- Tends to recur in graft
Salzmann’s Nodular Degeneration
- Statistics?
- Associations?
- What does it look like?
- Symptoms?
- Complications?
- Treatment?

- Female >> males
- 72-88%
- Caucasian
- 6th decade
- Bilateral
- 58-67%
-
Associations
- Idiopathic
- Corneal inflammatory disease
- MGD, ocular rosacea
- Phlyctenular disease
- Vernal keratoconjunctivitis
- Trachoma
- Interstitial keratitis
-
Yellow-white to blue elevated nodular lesions
- Single or multiple
- Usually in annular pattern in mid periphery
- Adjacent to corneal scars or pannus
- Iron lines may be present surrounding lesions
- Vascularization may be adjacent to lesion
-
Symptoms
- Asymptomatic 15%
- FBS
- Possible to develop epi-erosions over lesions →
- Pain
- Lacrimation
- Photophobia
- Decreased VA possible if nodule over visual axis
-
Complications
- Corneal erosion
- Photophobia
- Blepharospasm
- Lacrimation
- Corneal Irregularity
- Hyperopic shift
- Irregular astigmatism
-
Treatment
- Lubrication
- Warm compressess
- Lid hygiene
- Topical steroids
- Superficial keratectomy (Super-K)
- Lamellar or penetrating keratoplasty
- Recurrence possible

Senile Furrow Degeneration
- What does it look like?
- Where does it occur & diameter?
- Symptoms?
- Treatment?

- Rare, idiopathic
-
Shallowing thining in the avascular zone between acrus senilis & limbus in elderly pt
- Occurs circumferentially
- <0.5mm width
- Shallow
- No visual significance
- No inflammation or vascularization
-
Symptoms
- Asymptomatic
- Not visually significant
-
Treatment
- None
Fusarium
- Filamentous
- Widely distributed in plants/soil
- Readily colonize on tissue that has been injured by other means
- Thrives in hot, humid environments
- Can grow on improperly cleaned CLs
Congenital hereditary stromal dystrophy
- Characteristics?
- Symptoms?
- Treatments?

-
AD inheritance
- Cornea clear at birth, clouding begins at 1-2yrs
-
AR inheritance
- opacification appears w/in neonatal period
-
Mutation of DCN gene
- codes for decorin protein
- Non-progressive to slowly progressive
- Thought to be caused by disordered stromal fibrogenesis
- Diffuse haze with flaky lesions in central anterior stroma
- Ground glass corneal apperance
-
Symptoms
- Decreaseed VA
- Dense amblyopia
- Esotropia
- Nystagmus - associated with AR form
-
Treatment
- PK at early age
What are the dimensions of the cornea?
- 11-12mm H x 9-11 mm V
- 0.5mm centrally
- 0.7mm peripherally
Clinical Exams and Diagnostic testing for keratoconus?
Clinical Exam
- Assessment of vision: c/o ghosting or smeared images
- Retinoscopy: Scissor reflex retinoscopy
- Refraction: inability to correct vision to 20/20
-
External exam:
- look at lids (including eversion) for signs of atopy
- Munson sign
-
Slit lamp examp
- Thorough corneal evaluation
- Look for surgical scars
- Presence & location of thinning
Diagnostic Testing
-
Keratometry
- Done in normal gaze position - failure to superimpose rings
- Repeat in upgaze (to capture steepest portion of cornea)
- No specific K-value that defines KCN
-
Pachymetry
- Compare thinning to “normal” corneas
- Can achieve with ultrasound or optically pachys
-
Corneal topography
- Placido disk
- Scheimpflug photography (Pentacam)
- Anterior segement OCT
-
Specular microscopy
- show evidence of endothelial cell damage
-
Aberrometry
- Vertical coma is most typical aberration
Lab work up for bacterial keratitis?
- Indicated in cases where corneal infiltrate is central, large, deep, chronic, or has atypical features suggestive of fungal, amoebic, or mycobacterial keratitis
- Corneal scraping for culturing
- Cytology
- Gram staining
- Susceptibility testing
- Start tx empirically after scraping with broad spectrum & adjust tx once results come in
Describe the reactivation infection for Herpes simplex?
- Reactivation infection
- Latency in sensory ganglia - ocular infection latency occurs in trigeminal gnaglia
- Viral replication leads to cytopathic effects in cells, or immune response to virion
- Clinical disease varies based on reaction to virus
- Reactivation can occur at any time
- Blepharoconjunctivitis
- Keratitis - epithelial, stromal or endothelial disease
- Uveitis
- Retinitis
- Any ocular structure possible
- Latency in sensory ganglia - ocular infection latency occurs in trigeminal gnaglia
- More likely to cause severe visual consequences from scarring & inflammation
- Essential to make a prompt diagnosis & initiate tx to preserve ocular function
- Careful evaluation of each ocular structure is critical
Blunt Force Trauma
- Injury from impact of noncutting instrument
-
Contusive: direct impact
- Bruising or fractures
- Concussive: rapid acceleration, deceleration, or oscillation of tissues causing energy transfer to surrounding tissues
- Damage often not localized to only the cornea
- Diffuse endotheliopathy
- Endothelial rings
- Stromal injury & fracture
LASEK
- Laser epithelial keratomileusis
- Hybrid of PRK & LASIK
-
Procedure
- Epithelium softened with alcohol & rolled back
- Laser ablation of stromal tissue
- Epithelium rolled back into place
-
Benefits
- Reduced post-op haze
- Increase healing time
- Reduce post-op pain
Reis-Bucklers Corneal Dystrophy (CBD I)
- Characteristics
- Mutation of which gene?
- Presentation?
- Symptoms?
- Treatments?

- AD
- Presents in 1st decade of life
- Born with normal corneas
-
TGFB1 gene mutation
- Subepithelial reticular changes
- Deposits of hyaline-like material that disrupts & may replace bowmans
- Subepithelial reticular changes
- Progress until middle age
-
Presentation
- Fine, reticular superficial opacities
- Become honeycomb-shaped
- Diffuse superfical haze
- Increased central corneal thickness
- Irregular astigmatism
- Decreased corneal sensation
- Prominent corneal nerves visible
-
Symptoms
- Episodic corneal erosions
-
Vision loss
- Irregular astigmatism & opacification
- Occurs early in life
-
Treatments
- Bandage CLs
- Lamellar keratoplasty
- Penetrating keratoplasty
Filamentary keratopathy
- Characteristics
- Clinical signs
- Causes
- Symptoms
- Treatment

- Women>Men
- Incidence increases with age
- Filaments attach to corneal epithelium
-
Filaments adherent to corneal epithelium
- Loose area of epithelium acts as a focus for deposition of mucus & cellular debris
- Filaments small, gelatinous strands
- Differ in size, composition & distribution
- 0.5-10mm
- Differ in size, composition & distribution
- Location of filament helps assist in diagnosis of underlying cause
- Abnormally high mucous to aqueous
- Aqueous deficiency
- Increased mucin production
Clinical Signs
- Strands of degeneration epithelial cells & mucs that move with blinking, attached at one end to the cornea
- Small epithelial defect may be present at the base of filaments
- Chronic filaments → plaques
- Filaments stain well with rose bengal, less with NaFL
Causes
- Aqueous deficiency DES
- Excessive CL wear
- Corneal epithelial instability
- SLK
- Bullous keratopathy
- Neurotrophic keratitis
- Prolonged or frequent eye closure
- Ocular surgeries
Symptoms
- Discomfort with mild to severe FBS
- Redness
- Occasional photophobia
- Epiphora (overlow of tears)
- Blepharospasm
Treatment
- Treat underlying cause
- D/C all unnecessary medications
- Manual removal of filaments
- Mucolytic agent - acetylcysteine
- Tropical NSAIDs
- Hypertonic saline
- Bandage CL
- Punctal occlusion
Spheroidal Degeneration
- What other names is it also known as?
- Statistics? (Men/Women, Bilateral/Uni)
- Etiology?
- What does it look like? Diameter range?
- What are the 3 types?
- Complications?
- Treatment?

-
AKA
- Labrador keratopathy
- Bietti nodular hyaline bandshape keratopathy
- Climatic droplet keratopathy
- Proteinaceous corneal degeneration
- Elastotic degeneration
- Fisherman’s keratopathy
- Eskimo’s corneal degeneration
-
Bilateral
- Unilateral, asymmetric cases possible
- Men > Women
- Asymptomatic until crosses visual axis
-
Etiology
- UV exposure
- Microtrauma
- Disease entities associated with neovascularization
-
Clear, to yellow-gold spherules seen in subepithelium, within bowman’s, or in superficial corneal stroma
- Proteinaceous material
- 0.1-0.4mm in diameter
- Continued exposure → coalescence & enlargement of spherules extending deeper corneal stroma & centrally across corneal surface creating a band
- Darken with age: Light yellow → brownish-yellow
- Proteinaceous material
-
3 Types
-
Primary corneal involvement
- Age-related
- Starts nasally → temporally (3&9 o’clock) near limbus
-
Corneal involvements secondary to underlying process
- Previous corneal disease/trauma
- May be diffuse or begin centrally
-
Conjunctival involvement
- May occur with type 1 or 2
- Begins 3 & 9 o’clock on conj
- Lesions smaller & less numerous
- May be present with pinguecula
-
Primary corneal involvement
-
Complications
- Decreases vision
- Epithelial disruptions
- Ulceration of tissue
- Hypoesthetic or anesthetic
- Often become infected
- Cicatricial changes to cornea or conjunctiva
-
Treatment
-
None-asymptomatic
- Observation
- UV protection
- Surgical
- Penetrating keratoplasty (PK)
- Phototherapeutic keratectomy (PTK)
- Excision of conjunctival lesions
-
None-asymptomatic

Bacterial Keratitis Presentation?
- Depends on causative organism, duration of infection, pre-existing conditions, immune status of pt, & previous drug use (antibiotics, steroids, etc)
- Pain
- Photophobia
- +/- decreased vision
- depends on location of ulcer & severity
- Marked conjunctival injection
- anterior chamber reaction
- +/- Hypopyon
- Pupillary constriction & ciliary flush
- Lacrimation
- Discharge
- Generally mucopurulent
- Tissue loss
- Ragged,irregular epithelial ulceraction with underlying necrotic stroma infiltrations & surrounding epithelial edema
DMEK
- Descemet’s Membrane Endothelial Keratoplasty
- Transplant of endothelium
- Donor tissue includes Descemet’s membrane & endothelium, doesn ot include stromal tissue
- Benefits
- Improved acuity after surgery
- Improved healing time
Note the difference between Terrien’s vs. Senile Furrow Degeneration

List types of corneal surgeries
- Refractive Surgeries
- Transplants
- Other
Refractive surgeries
- LASIK
- PRK
- LASEK
- RK/AK
- Phakic IOLs
- ICL
- Verisyse
Transplants
- PK/PKP
- DALK
- DSEAK
- DMEK
Other
- PTK
- Super-K
Corneal Foreign Body
- What is it?
- Presentation
- Symptoms
- Examination
- Treatment
- One of the most common ocular traumas
- Often occur at work
- Most often pts not wearing eye protection
-
Symptoms
- Pain
- Photophobia
- Tearing
- Inability to open eye
- Redness
-
Presentation
- Generally obvious FB
- Multiple FBs are common
- Rust ring
- Conjunctival injection
-
Examination
- History: pt specific about injury
- VA: may/may not be reduced depending on location
- SLE: anesthetic, seidel sign, everts lids
- DFE: check for intraocular FB
-
Treatment
-
Superficial
- Removal at slit lamp
- Treat as abrasion
-
Deep/Penetrating
- DO NOT REMOVE
- Protect eye with fox shield
- Send to cornea specialist for surgery
-
Superficial
Stromal corneal Abrasions
- Uncommon
- Injury extends into stromal tissue = WILL SCAR
- Without flap: treat like epithelial abrasion
-
With flap:
- Smooth: BCL until surface reepithelializes, then
- Rough: sutures
- More likely to need specialty CL fitting or surgical repair


































































