BCSC Cornea Flashcards
How long does it take eyelashes (cilia) to re-grow when pulled out?
2 months
What type of gland are the glands of Moll?
apocrine sweat glands
What type of gland are the glands of Zeis?
sebaceous glands
What are the different morphologies (and their locations) of the conjunctival epithelium?
1) stratified cuboidal over tarsus
2) columnar in the fornices
3) squamous over the globe
What is the blood supply of the bulbar conjunctiva?
anterior ciliary arteries branching from the ophthalmic artery
What is the blood supply of the palpebral conjunctiva?
It is the same as the blood supply of the eyelids
What is the sensory innervation of the conjunctiva?
Several branches of V1 (lacrimal, supraorbital, supratrochlear, infraorbital)
What are the components of the lacrimal functional unit?
1) lacrimal glands
2) ocular surface (cornea, conj, meibomian glands)
3) eyelids
4) the innervation of all the above
What is the average blink rate in adults?
Approximately 15 times/minute
What are the three (traditional) components of the tear film?
1) lipid
2) aqueous
3) mucus
From which cells is the mucus content of the tear film secreted?
conjunctival goblet cells
What is the horizontal diameter of the adult cornea?
11-12 mm
What is the vertical diameter of the adult cornea?
10-11 mm
What is the average radius of curvature of the central cornea?
7.8mm
What proportion of the refractive power of a normal human eye is contributed by the cornea?
74% (43.25 D of 58.60 D)
What are the factors present in the corneal tear film?
EGF, lactoferrin, defensins, IgA, IL1-RA, TGF-beta, TIMP 1, MMP-9
From where does the sub-basal epithelium plexus of corneal nerves originate?
Long ciliary nerves
What are the neurotransmitters present in the cornea?
1) acetylcholine
2) catecholamines
3) substance P
4) calcitonin gene-related peptide
5) neuropeptide Y
6) intestinal peptide
7) galanin
8) methionine-enkephalin
What is the histologic type of the corneal epithelium?
Stratified squamous epithelial cells
What percent of the corneal thickness does the corneal epithelium make up?
5% to 10%
How do superficial epithelial cells prevent penetration of the tear film into the stroma?
with tight junctions in between superficial epithelial cells
How many days does it take for a proliferating perilimbal basal epithelial cell to differentiate into a superficial epithelial cell?
7-14 days
What is the composition of the corneal epithelial basement membrane?
Type IV collagen, laminin
What do keratocytes do?
They are flattened fibroblasts, located between collagen lamellae in the corneal stroma, and continually digest and manufacture stromal molecules
Is Bowman layer acellular?
yes
What are the primary collagen types seen in the corneal stroma?
Types I, V, and VI
How does the lattice arrangement of collagen fibrils in the stroma contribute to corneal transparency?
It acts as a diffraction grating, which reduces light scattering by means of destructive interference
Does the refractive index of the cornea increase or decrease moving from anterior to posterior?
Decrease
How does the hydration status of the cornea vary from anterior to posterior?
Increasingly hydrated posteriorly
Of what is the Bowman layer composed?
Type I collagen fibrils (it is stronger than the stroma proper)
Of what is sclera composed?
Type I collagen, proteoglycans, elastin, and glycoproteins
What are the 3 major types of direct illumination?
1) Diffuse illumination
2) Focal illumination
3) Specular reflection
What are the 3 major types of indirect illumination?
1) Proximal illumination
2) Sclerotic scatter
3) Retroillumination
How do guttae and keratic precipitates appear on specular reflection?
Non-reflective dark areas
Sclerotic scatter takes employs what optical phenomenon?
Total internal reflection
Sclerotic scatter is effective for identifying which corneal findings?
1) epithelial edema
2) stromal infiltration
3) cornea verticillata
How is tear breakup time measured?
1) Instill fluorescein
2) Ask patient to blink 2-3 times
3) Ask patient to hold eye open without blinking and use timer
4) Amount of time required for formation of dry spot is the TBUT
What TBUT is considered normal?
> = 10 seconds
How is a Seidel test performed?
1) Apply fluorescein with a moistened strip or concentrated drop to site of suspected leakage
2) View with cobalt blue filter, and look for clear fluid streaming through the dye
Where is true positive fluorescein staining seen?
Areas of epithelial defects
Where is staining with Rose Bengal or Lissamine Green seen?
Epithelial cells for which the protective mucin coating has been disrupted
Rose Bengal and Lissamine Green are useful for detecting which neoplasm in particular?
Corneal intraepithelial neoplasia (CIN)
What does the “Basic Secretion Test” measure?
basic (basal) tearing rate
How is the Basic Secretion Test performed?
1) Topical Anesthetic
2) Test Strip x 5 minutes
low (aqueous tear deficiency)
3-10mm equivocal
How is Schirmer I performed?
Same as Basic Secretion Test, but NO anesthetic
1) Test strip x 5 minutes
low (aqueous tear deficiency)
How is Schirmer II performed?
1) Topical Anesthetic
2) Nasal mucosa irritation with cotton swab
3) Test Strip x 2 minutes
deficient reflex tearing
What does Schirmer I measure?
Basal + Reflex tearing
What does Schirmer II measure?
Reflex tearing (after stimulation)
How is Schirmer II different from Schirmer I?
Schirmer II adds topical anesthetic and nasal irritation, and is only for 2 minutes. Schirmer II tests only reflex tearing, as opposed to reflex + basal (Schirmer I).
Does tear film hyperosmolarity indicate dry eye?
Yes
What do reduced levels of tear film lysozyme or lactoferrin indicate?
Dry eye
What is impression cytology?
The harvesting of cells from the ocular surface with a pice of filter paper for microscopic evaluation and/or flow cytometry.
What is the average central corneal thickness of the normal adult human cornea?
540 microns
Where is the thinnest zone of the cornea usually located?
1.5mm temporal to the geographic center
Increase in corneal thickness by what percentage is required for Descemet folds to be seen?
10%
What is the corneal apex?
The steepest point on the cornea
What is the corneal vertex?
The point at the intersection of the patient’s line of fixation and the corneal surface
What is the power of the posterior corneal surface?
-6 D
Total power = 43 D = 49 D - 6 D
What is the derived corneal refractive index normally used for computing central corneal power?
1.3375
Do mires of a placido disc-based topographer appear closer together or farther away in steep portions of the cornea?
Closer together
What are the three commonly used methods to describe corneal curvature?
1) axial curvature
2) instantaneous radius of curvature
3) mean curvature
What are factors that may affect the accuracy of corneal topography?
1) misalignment
2) test-to-test variation
3) focusing errors
4) tear-film effects
5) distortions
6) variation in area of coverage
What are common situations in which corneal topography is used?
1) IOL calculations
2) Contact lens fitting
3) Refractive surgery
4) Evaluation of keratoconus or other corneal ectasias
What is the normal axial resolution of ultrasound biomicroscopy (UBM)?
35 microns to 70 microns
Is UBM able to provide visualization of internal structures such as the iris in “eight-ball” hyphema?
Yes
What is the axial resolution of anterior segment OCT at present?
5 microns to 10 microns
What are the 4 forms of confocal microscopy that have been described for clinical use?
1) tandem-scanning
2) slit scanning
3) laser scanning
4) single-sided disc
What is the axial resolution of laser scanning confocal microscopes?
1-2 microns
What is the normal endothelial cell density in adults?
2400 cells/mm^2
What is the normal endothelial cell density in children?
3500 cells/mm^2
What is polymegathism?
Increased variation in individual endothelial cell areas
How can retinoscopy detect irregular astigmatism?
By demonstrating nonlinear or multiple reflexes that cannot be completely neutralized with a spherocylindrical lens
Where are conjunctival papillae most easily seen?
in the palpebral conjunctiva in regions where fibrous septa anchor the conjunctiva to the tarsus
What are conjunctival papillae?
Dilated, telangiectatic conjunctival blood vessels surrounded by edema and a mixed inflammatory cell infiltrate
What are conjunctival follicles?
Focal lymphoid nodules with accessory vascularization
Does chlamydial conjunctivitis usually present with conjunctival follicles or papillae?
Follicles
Is drug-induced conjunctivitis usually follicular or papillary?
Follicular
What are three common causes of conjunctival granulomas?
1) Cat-scratch disease
2) Sarcoid
3) Foreign body
How large must a conjunctival papilla be to be classified as “giant?”
Diameter > 0.3mm
What do dot and strand keratic precipitates usually comprise?
Fibrin
What do punctate keratic precipitates usually comprise?
Neutrophils and lymphocytes
What do mutton-fat KPs usually comprise?
macrophages
Incorporation of what materials may lead to dark pigmentation of a corneal opacity?
melanin or iron salts
From where does corneal NV usually arise?
Limbal blood vessels in the palisades of Vogt
What is subepithelial fibrous ingrowth into the peripheral cornea called?
Pannus
What are the core mechanisms thought to be involved in dry eye?
1) Hyperosmolarity
2) tear-film instability
3) Inflammation
What impact does tear hyperosmolarity have on the corneal epithelium?
Induction of inflammation and subsequent disruption of tight junctions between epithelial cells
What are the two common classifications of Dry Eye?
1) Aqueous tear deficiency
2) Evaporative
What are common causes of tear-film instability?
1) MGD
2) Vitamin A deficiency
3) contact lens wear
4) Exposure
5) antihistamines
6) topical medications with preservatives such as BAK
What is the mechanism of aqueous tear deficiency in Sjogren syndrome?
T-cell mediated inflammation of the lacrimal gland –> diminished tear production and propagation of inflammatory mediators on the ocular surface
A tear meniscus of less than what height is considered abnormal?
< 0.3 mm
Of what are the filaments in ATD composed?
Strands of epithelial cells attached to the corneal surface over a core of mucus
What is the appearance of the meibomian gland in MGD?
The meibomian gland orifices may pout or show metaplasia, with a white plug of keratin extending through the glandular orifice
How does atrophy of the meibomian glands appear?
absence of the vertical lines of the meibomian glands, best seen with transillumination of the everted eyelid or infrared photography
Which classes of systemic medications are known to be associated with dry eye?
1) diuretics
2) antihistamines
3) anticholinergics
4) psychotropics
What are demulcents?
Polymers added to artificial tear solutions that can briefly substitute for glycoproteins absent in late stage dry eye.
What percent of patients with moderate to severe ATD benefit from the use of topical cyclosporine A?
50%
What is required for the generation of autologous serum tears?
3-4 red top tubes of blood
Patients with filamentary keratopathy associated with dry eye are often treated with which agent?
topical acetylcysteine 10%
Are cholinergic agents approved for the stimulation of tear secretion in Sjogren syndrome?
not presently in the US, but pilocarpine and cevimeline are approved for the treatement of xerostomia
Which medications can be effective in MGD?
1) topical azithromycin
2) topical corticosteroids
3) systemic tetracyclines (usually doxycycline 100mg bid x 3-4 weeks, tapering to 40-100mg daily)
What impact has omega-3 supplementation been seen to have on MGD?
1000mg tid x 1 year improved symptoms, tear-film stability, and meibomian secretions; other studies have demonstrated increases in tear production, which would indicate a potential role in therapy for ATD as well
With which peptides is rosacea thought to be associated?
Cathelicidin antimicrobial peptides
What are cathelicidins?
Peptides that cause neutrophil recruitment, angiogenesis, and cytokine release
What are the common ocular findings in rosacea?
1) eyelid margin telangiectasia
2) meibomian gland distortion
3) blepharitis
What are severe ocular manifestations of rosacea?
1) chronic conjunctivitis
2) marginal corneal infiltrates
3) sterile corneal ulceration
4) episcleritis
5) iridocyclitis
What is the mainstay of treatment of the ocular manifestations of rosacea?
tetracyclines
What are the 3 primary forms of blepharitis?
1) Staphylococcal
2) MGD
3) Seborrheic
What is poliosis?
Condition of having white eyelashes
In which form(s) of blepharitis is eyelash loss or whitening common?
Staphylococcal blepharitis
With what is staphylococcal blepharitis often associated?
1) matted golden crusts and ulcers on the anterior eyelid margin
2) inferior PEE
3) marginal corneal infiltrates
4) conj or corneal phlyctenules
What is phlyctenulosis?
a local corneal or conjunctival inflammation thought to be due to cell-mediated or delayed hypersensitivity response to S. aureus or M. tuberculosis
What is the common appearance of a phlyctenule?
small, rounded, elevated, gray or yellow, hyperemic, focal inflammatory nodule present at or near the limbus, accompanied by a zone of engorged vessels
What are hordeola?
Red, painful, tender, nodular masses at the eyelid margin related to glands at the eyelid margin
Hordeola of the anterior eyelid margin (external hordeola) are related to which glands?
Glands of Zeis
Hordeola on the posterior eyelid margin (internal hordeola) are related to which glands?
Meibomian glands
What are chalazia?
chronic lipgranulomatous nodules involving either the meibomian glands or the glands of Zeis
What are options for management of hordeola?
Warm compresses, lid hygiene, doxycycline
Intralesional injection of what type of drug can be useful in treatment of recalcitrant small chalazia?
corticosteroids (0.1-0.2 mL triamcinolone 40mg/mL)
What are the clinical features of floppy eyelid syndrome?
1) lax superior tarsus that everts with minimal force
2) papillae on superior palpebral conjunctiva
3) mucus discharge
4) PEE
Is floppy eyelid syndrome more common in obese or normal BMI individuals?
Obese individuals
What are possible treatments for floppy eyelid syndrome?
eye shield, taping eyelids closed at night, surgical eyelid tightening
What are the clinical features of superior limbic keratoconjunctivitis (SLK)?
1) papillary reaction of superior tarsal conj
2) injection and thickening of superior bulbar conj
3) hypertrophy of superior limbus
4) punctate staining of superior bulbar conj
5) superior filamentary keratopathy
With which autoimmune disease is SLK associated?
autoimmune thyroid disease (Graves disease)
Is SLK more common in men or women?
Women (20-70 years old)
Is SLK usually self-limited?
Yes
What is the proposed mechanism of action of doxycycline in treating recurrent corneal erosion?
Inhibition of matrix metalloproteinases
What are surgical therapies for recurrent corneal erosion?
1) stromal micropuncture
2) epithelial debridement
3) PTK
What is the goal of stromal micropuncture in recurrent corneal erosion?
microcicatrization between epithelium, Bowman layer, and stroma
What are the key aspects of management of neurotrophic keratopathy?
1) remove corneal sensation reducing meds
2) maintain lubrication (with PFATs, possibly scleral contact lens to create fluid reservoir)
3) eliminate any exposure (possibly with tarsorrhaphy)
4) reduce mucus production
5) prevent bacterial infection (with antibiotics, epi defect closure with AMT)
6) reduce MMP action (possibly with tetracyclines)
7) restore trophic factors (possibly with autologous serum tears)
What is trichiasis?
an acquired condition in which eyelashes emerging from their normal origin curve inward toward the cornea
What is distichiasis?
a condition in which an extra row of lashes emerges from the ducts of the meibomian glands
What are the epithelial changes seen with topical anesthetic use?
1) Inhibition of epithlelial migration and division
2) loss of microvilli
3) reduction of desmosomes
What are dellen?
saucer-like depressions in the corneal surface, usually related to an are of dehydrated corneal stroma
What percent of the corneal limbus must be intact to ensure normal ocular resurfacing?
25-33%
Mutation in which gene can be a cause of primary limbal stem cell deficiency?
PAX6 gene (aniridia)
What are the major classes of causes of limbal stem cell deficiency (LSCD)?
1) Idiopathic
2) Traumatic
3) Iatrogenic
4) Autoimmune
5) Acquired eye disease
6) Congenital eye disease
Which topical medications can cause LSCD?
1) pilocarpine
2) beta blockers
3) antibiotics
4) antimetabolites
What are the surgical therapies for LCSD?
1) limbal or conjunctival autograft
2) limbal allograft
3) keratoprosthesis
What is the difference between primary and secondary Sjogren syndrome?
Primary Sjogren syndrome patients do not have a well-defined connective tissue disease, while those with Secondary Sjogren syndrome do.
What is the most commonly associated connective tissue disease in secondary Sjogren syndrome?
RA
What are common ocular findings in the icthyoses?
1) eyelid scaling (hyperkeratosis)
2) cicatricial ectropion
3) conjunctival thickening
What are the characteristics of an ectodermal dysplasia?
1) presence of abnormalities at birth
2) nonprogressive course
3) involvement of the epidermis plus at least one of the hair, nails, teeth or sweat glands
What are the ocular manifestations of Xeroderma Pigmentosum?
1) photophobia
2) tearing
3) blepharospasm
4) features of keratoconjunctivitis sicca
Vitamin A deficiency results in dryness associated with loss of which cells?
The conjunctival goblet cells, thus causing a reduction in mucus production
What is a Bitot spot?
a superficial foamy gray triangular area on the bulbar conjunctiva consisting of keratinized epithelium, inflammatory cells, debris, and Corynebacterium xerosis. The Bitot spot is seen in Vitamin A deficiency
What function does lactoferrin serve in the tear film?
Lactoferrin inhibits bacterial metabolism and facilitates tear antibody function and complement activation
What function does lysozyme serve in the tear film?
Tear lysozyme degrades bacterial cell walls
What function does beta-lysin serve in the tear film?
Tear beta-lysin disrupts bacterial plasma membranes
What are the predominant ocular flora in the an infant?
S. aureus, S. epidermidis, strep species, E. coli
How does acanthamoeba adhere to the corneal surface?
Through the expression of a mannose-binding protein that attaches to surface epithelial cells
Which bacteria are known to be able to overcome an intact corneal epithelium?
1) N. gonorrhoeae
2) N. meningitidis
3) C. diptheriae
4) Shigella species
5) H. flu biotype III
6) L. monocytogenes
What are two factors produced by psuedomonas to invade the cornea?
elastase and alkaline protease
What are the recommended culture media for aerobic bacteria in the setting of a microbial keratitis?
1) blood agar
2) chocolate agar
3) thioglycollate broth
What are the recommended culture media for anaerobic bacteria in the setting of a microbial keratitis?
1) Anaerobic blood agar
2) Phenylethyl alcohol agar in anaerobic chamber
3) Thioglycollate or meat broth
What are the recommended culture media for mycobacteria in the setting of a microbial keratitis?
1) blood agar
2) Lowenstein-Jensen agar
What are the recommended culture media for fungi in the setting of a microbial keratitis?
1) Blood agar
2) Sabourad’s agar
3) Brain-heart infusion agar
What are the recommended culture media for acanthamoeba in the setting of a microbial keratitis?
1) Non-nutrient agar with bacterial overlay
2) blood agar
3) Buffered charcoal-yeast extract agar
For which type of microbial keratitis is a Giemsa stain most often recommended?
Acanthamoeba keratitis
Are enveloped viruses (such as HSV) susceptible to damage by alcohols and general-use antiseptics?
Yes
What is the most common systemic manifestation of primary HSV infection?
URI
What is the typical manifestation of primary ocular HSV infection?
blepharoconjunctivitis
What are the classic signs of an acute primary HSV ocular infection?
1) cutaneous or eyelid margin vesicles (or ulcers on the bulbar conjunctiva)
2) dendritic epithelial keratitis
What is a common manifestation of an adenoviral keratoconjunctivitis that is rarely seen in HSV ocular infection?
conjunctival membranes or pseudomembranes
What is the mechanism of recurrent HSV ocular infection?
1) reactivation of latent virus present in an infected sensory ganglion (trigeminal ganglion)
2) transport of virus to sensory nerve endings
3) re-infection
Is recurrent ocular HSV usually unilateral or bilateral?
Unilateral (97%)
What are the common symptoms of a patient with HSV epithelial keratitis?
1) FBS
2) light sensitivity
3) redness
4) blurred vision
What is a distinguishing characteristic of the dendritic ulcers associated with HSV epithelial keratitis?
terminal bulbs
Where and how does an HSV corneal ulcer stain?
1) bed of ulcer stains with fluorescein (loss of epithelial tight junctions)
2) edges of ulcer stain with rose bengal/lissamine green (epithelial devitalization/loss of mucin binding at site of active viral replication)
The application of steroids to an active HSV epithelial keratitis can result in what?
Enlargement of a dendritic ulcer into a geographic ulcer
What are tests that can be done to confirm HSV as a cause of a dendritic epithelial keratitis?
1) intranuclear inclusions on corneal scrapings
2) tissue culture
3) ELISA
4) PCR
What treatment options are available for HSV epithelial keratitis?
1) technically, observation, as it is generally self-limited
2) epithelial debridement
3) topical antiviral therapy (topical trifluridine 1% 8x/day, topical ganciclovir gel)
4) oral antiviral therapy (acyclovir, valacyclovir)
What is the most common cause of infectious corneal blindness in the US?
HSV stromal keratitis
What is herpetic interstitial stromal keratitis?
unifocal or multifocal haze or whitening of hte stroma in the absence of epi defect
What is a ddx for herpetic interstitial stromal keratitis?
1) VZV keratitis
2) Acanthamoeba keratitis
3) syphilis
4) EBV keratitis
5) mumps keratitis
6) Lyme disease
7) sarcoid
8) Cogan syndrome
Where is the primary source of inflammation in herpetic disciform keratitis?
The endothelium (although stromal and epithelial edema are the more visible signs on exam)
Is there active viral replication in HSV stromal keratitis?
No, HSV stromal keratitis is thought to be primarily inflammatory
Is a treatment dose or prophylactic dose of antiviral drug used with HSV stromal keratitis?
A prophylactic dose (e.g., trifluridine qid, acyclovir 400 bid, or valacyclovir 500 daily)
Can herpetic infection lead to neurotrophic keratopathy?
Yes
What is the common appearance of a neurotropic ulcer?
rolled edges with gray, elevated appearance
What percent of all cases of zoster involve V1?
15%
What percent of cases of zoster involving Vq have ocular involvement?
70%
How do the pseudodendrites of herpes zoster differ from the true dendrites of HSV epithelial keratitis?
1) lack of central ulceration
2) minimal staining with fluorescein or rose bengal
3) blunt ends rather than bulbous
What are the two forms of epithelial keratitis seen in HZO?
1) punctate epithelial keratitis
2) dendritic epithelial keratitis
What percent of patients with ocular manifestations of zoster develop diminished corneal sensation?
50%
What are the current treatment options for HZO antiviral therapy?
1) famciclovir 500mg PO tid
2) valacyclovir 1g PO tid
3) acyclovir 800mg PO 5x/day
all 7-10 days, ideally started within 72 hours of onset of skin lesions
Can amitriptyline reduce the duration of postherpetic neuralgia if given early in the course of HZO?
yes
What are the three forms of EBV keratitis?
1) subepithelial
2) anterior to midstroma ring-shaped opacities
3) deep or full-thickness infiltrates
What is the impact of antiviral therapy on the corneal manifestations of EBV infection?
Unknown at present
How can a diagnosis of CMV keratitis be confirmed?
PCR testing of aqueous obtained by AC tap during active disease. One may consider simultaneous serum testing to distinguish between systemic and local disease.
Is CMV keratitis responsive to famciclovir, acyclovir, or its derivatives?
No. However, it is responsive to ganciclovir. and valganciclovir.
What are the 3 classic clinical patterns associated with adenoviral eye infection?
1) simple follicular conjunctivitis (multiple serotypes)
2) pharyngoconjunctival fever (serotypes 3 or 7)
3) epidemic keratoconjunctivitis or EKC (serotypes 8, 19, 37, subgroup D)
Which of the adenoviral eye diseases has significant corneal involvement?
Epidemic keratoconjunctivitis (EKC)
What are the common findings of EKC?
1) follicular conjunctiviis with pseudomembranes or true membranes and petechial hemorrhages
2) corneal erosions
3) punctate epithelial keratitis (due to adenoviral replication in the epithelium)
For how long after the onset of symptoms in EKC does viral shedding typically occur?
10-14 days
To which virus family does molluscum contagiosum belong?
The poxviridae
What are the common clinical features of molluscum contagiosum infection?
1) follicular conjunctivitis
2) PEK
3) Smooth nodule with umbilicated central core
How can molluscum contagiosum lesions be managed?
1) excision
2) cryotherapy
3) incision of central portion of the lesion
Which serotypes of HPV are associated with malignant transformation?
16 and 18
Which viruses cause Acute Hemorrhagic Conjunctivitis (AHC)?
1) Enterovirus type 70
2) Coxsackievirus A24
3) Adenovirus type 11
What are the clinical features of Acute Hemorrhagic Conjunctivitis (AHC)?
1) petechial hemorrhages of bulbar and tarsal conj
2) eyelid edema
3) chemosis
4) PEK
5) Preauricular adenopathy
What is Demodex?
a genus of mites whose presence can be suggested by waxy “sleeves” around eyelashes extending from the eyelid margin
Are conjunctival membranes typically seen in H. influenzae conjunctivitis?
No
Do most cases of bacterial conjunctivitis resolve without treatment?
Yes, within 2-7 days.
Is gonococcal conjunctivitis generally indolent or rapidly progressive?
rapidly progressive
What is the recommended therapy for a non-penicillin-allergic patient with gonococcal conjunctivitis?
If no corneal ulcer: 1g ceftriaxone IM x 1
If corneal ulcer: 1g ceftriaxone IV q12h x 3 days
May consider oral therapy for possibility of concomitant chlamydial infection as well
In order of prevalence, which microbes are the most common causes of neonatal bacterial conjunctivitis?
1) Chlamydia trachomatis
2) Strep viridans
3) Staph aureus
4) H. influenzae
5) Group D Strep
6) M. catarrhalis
7) E coli
8) N gonorrhoeae
What is first-line therapy for non-disseminated neonatal gonococcal conjunctivitis?
IM or IV ceftriaxone 25-50mg/kg x 1
What is first-line therapy for neonatal chlamydial conjunctivitis?
Erythromycin 12.5mg/kg PO or IV qid x 14 days
What are the 3 primary forms of Chlamydial conjunctivitis?
1) trachoma (A-C)
2) adult and neonatal inclusion conjunctivitis (D-K)
3) lymphogranuloma venereum (L1, L2, L3)
What are the clinical features of trachoma?
1) severe follicular reactino, particularly involving the superior tarsal conjunctiva
2) (late) linear scarring of the superior tarsal conjunctiva (Arlt line)
3) Herbert pits (limbal depressions resulting from involution and necrosis of follicles)
4) epithelial keratitis and superficial fibrovascular pannus
What clinical features are required for diagnosis of trachoma?
At least 2 of the following:
1) conjunctival follicles on superior tarsal conjunctiva
2) limbal follicles and Herbert pits
3) typical tarsal conjunctival scarring (Arlt line)
4) vascular pannus, particularly at superior limbus
What is first-line therapy for active trachoma?
1) tetracycline 1% ophthalmic ointment bid x 2 months
2) azithromycin 1g PO x 1 dose
What is the quickest treatment for adult chlamydial conjunctivitis?
azithromycin 1g PO x 1 dose
What is Parinaud oculoglandular syndrome?
A granulomatous conjjunctivitis associated with regional lymphadenopathy, most often caused by Cat-scratch disease, which in turn is most often caused by Bartonella henselae.
What is the classic conjunctival manifestation of Parinaud oculoglandular syndrome?
Gelatinous, hyperemic, granulomatous lesions of conjunctiva developing 3-10 days after inoculation.
What is the relative risk of corneal infection in contact lens wearers vs. non-contact lens wearers?
10x
What is the most common bacterial pathogen in contact-lens related keratitis?
Pseudomonas aeruginosa
What percent of patients with culture-proven microbial keratitis are contact lens wearers?
19%-42%
Is the epithelial demarcation of corneal ulcers usually sharp or indistinct?
Epithelial border sharp. Stromal border indistinct.
Infectious crystalline keratopathy is usually associated with which types of organisms?
alpha-hemolytic Strep species
Infectious keratitis may occur with an intact epithelium due to which kinds of organisms?
slow-growing, fastidious organisms such as mycobacteria and anaerobes
Which organisms are most commonly seen in bacterial keratitis (of all causes)?
1) Staph aureus
2) Staph epidermidis
3) Strep pneumoniae
4) Pseudomonas aeruginosa
5) Enterobacteraciae
Initial cultures are recommended for corneal infiltrates with what characteristics?
1) extension into central cornea
2) extension into deep stroma
3) large area (> 2mm)
4) history or clinical features concerning for fungal, amoebic, mycobacterial or resistant organisms
Do 3rd and 4th generation fluoroquinolones have significant activity against MRSA?
No, they have limited activity against MRSA.
What are indications that an infectious keratitis is responding to antimicrobial therapy?
1) blunting of perimeter of stromal infiltrate
2) decreased density of stormal infiltrate
3) reduction of stromal edema
4) reduction in AC inflammation
5) re-epithelialization
6) cessation of corneal thinning
Which conditions should be met to consider instituting steroids in a patient with a presumed bacterial keratitis?
1) appropriate antibiotic therapy should be initiated
2) patient must be able to return for frequent follow-up examinations
3) no additional infectious organisms (superinfections) are suspected
Atypical mycobacterial infections have been identified in patients status post which type of refractive surgery?
LASIK
What percent of infectious keratitis is due to fungal infection?
5-10%
What are classic risk factors for fungal keratitis?
1) trauma to the cornea with vegetation
2) contact lens wear
3) topical corticosteroid use
Does fungal keratitis tend to present with more or less evidence of inflammation than bacterial keratitis?
Less evidence of inflammation is seen in fungal keratitis
Which media are preferred for fungal culture?
Blood, Sabourad, and brain-heart infusion media
Which agent is considered first line for a fungal keratitis caused by a filamentous fungus?
Topical Natamycin 5% suspension
Which agent is considered first line for a fungal keratitis caused by a yeast?
Topical amphotericin B (0.15% to 0.30%)
Which filamentous fungal keratitis usually treated with amphotericin B as opposed to natamycin?
Aspergillus sp.
Which systemic azoles are preferred for fungal keratitis?
Voriconazole and posaconzaole, for their excellent intraocular penetration and broad spectrum of coverage
Where are acanthamoebae found?
fresh water and soil
What are the two primary forms of acanthamoeba?
1) motile trophozoites
2) dormant cysts
What is the classic presentation of amebic keratitis?
1) severe pain
2) photophobia
3) central stromal infection
4) radial keratoneuritis
5) ring infiltrate (late stage)
What is the preferred medium for culturing acanthamoeba?
Non-nutrient agar with E coli or Enterbacter aerogenes overlay
Which class of drugs is the only class to have been demonstrated to have consistent clinical and in vitro efficacy against both cysts and trophozoites when applied topically?
Biguanides (PHMB and chlorhexidine)
What are common causes of non-suppurative stromal keratitis?
1) reactive arthritis
2) congenital or acquired syphilis
3) lyme disease
4) tuberculosis
5) leprosy
6) onchocerciasis
What are the two distince clinical presentations of microsporidial infections?
1) immunocompetent – stromal keratitis
2) immunocompromised – epithelial keratopathy
Is there a definitive treatment of microsporidial keratitis?
No, however, restoration of immune function can lead to resolution and topical fumagillin has been used to successfully treat microsporidial keratitis
What is loa loa?
a filarial worm that can burrow subcutaneously to reach the periorbita. It can cause a conjunctivitis treated by extraction of the worm and antiparasitic treatment for disseminated infection.
What are risk factors for microbial scleritis?
1) trauma
2) contaminated foreign body (e.g. scleral buckle)3) pterygium surgery, esp. with irradiation or MMC
Which immune cells are seen in non-inflamed conjunctiva?
1) PMNs
2) lmphocytes (including Treg cells)
3) dendritic cells (APCs), with Langerhans cells in the epithelium
Which immune cells are seen in non-inflamed cornea?
1) dendritic cells (Langerhans cells in the epithelium), primarily in the periphery/limbus
2) lymphocytes (peripheral)
What factors contribute to the immune privilege of the healthy cornea?
1) absence of blood vessels
2) absence of lymphatics
3) expression of ummunosuppressive factors (TGF-beta, neuropeptides)
4) expression of Fas-ligand (aids in apoptosis of activated lymphocytes)
5) exposure to AC, wich contains immunosuppressive factors (such as corticosteroid)
What is the risk of immune rejection after PK in the presence of corneal NV?
> 50%
What are the primary components of immune response of conjunctiva?
1) Humoral – IgA produced by lacrimal gland
2) Cellular – CD4+ T cells, mast cells
What is a Wessely immune ring?
a annular infiltrate in the corneal stroma containing complement factors and neutrophils formed in response to foreign antigen (to which the host is sensitized)
Which medications are commonly associated with contact blepharoconjunctivitis?
1) cycloplegics (atropine and homatropine)
2) aminoglycosides (neomycin, gentamicin, tobramycin)
3) antivirals (idoxuridine, trifluridine)
4) preservatives (thimerosal, EDTA)
Which agents can be used in a severe delayed hypersensitivity contact blepharoconjunctivitis?
1) topical corticosteroid
2) tacrolimus ointment
What is atopic dermatitis?
A chronic condition in genetically susceptible individuals, usually beginning in infancy or childhood. It involves type IV hypersensitivity, IgE hypersensitivity, increased histamine release, and impaired cell-mediated immunity. It differs from contact dermatitis in that atopic dermatitis is a chronic condition.
What type of hypersensitivity reaction occurs in seasonal allergic conjunctivitis/perennial allergic conjunctivitis?
Immediate type (type I) hypersensitivity reaction
What is the typical demographic of patients affected by vernal keratoconjunctivitis?
young males (1st or second decade)
Which types of hypersensitivity are thought to be involved in vernal keratoconjunctivitis?
Types I and IV
What are the two clinical forms of VKC?
1) Palpebral
2) Limbal
What is the typical population affected by Limbal VKC?
People in hot climates, typically of African or Asian descent
What are Horner-Trantas dots?
white, gelatinous-appearing, round microaggregrates of degenerated eosinophils and epithelial cells seen at the corneal limbus in limbal VKC
Where is the shield ulcer typically seen in VKC?
superior cornea
What treatments are used for VKC?
1) topical antihistamines/mast cell stabilizers
2) topical pulsed or supratarsal injection of steroid
3) topical cyclosporine 2%
4) topical tacrolimus 0.1%
What proportion of patients with atopic dermatitis develop AKC?
1/3
What type of hypersenstivity reaction is typically seen in AKC?
Type IV
Are patients with AKC typically younger or older than those with VKC?
Older
Is conjunctival scarring more or less common in AKC than VKC?
More common in AKC
Is AKC typically year-round?
Yes, as opposed to VKC, which is typically vernal (springtime-related)
Colonization of the eyelids with which species is often seen in AKC?
S. aureus
What are the classic lesions of ligneous conjunctivitis?
Firm “woody” yellowish fibrinous pseudomembranes on the conjunctival surface
What is the deficiency that appears related to the development of ligneous conjunctivitis?
Deficiency in type I plasminogen, which results in hypofibrinolysis
Is ligneous conjunctivitis typically recurrent after surgical excision of lesions?
yes
Which drugs are most commonly associated with SJS/TEN?
sulfonamides
anticonvulsants,
NSAIDs
allopurinol
What percent of SJS/TEN are thought to be drug indued?
80% of TEN, 50-80% of SJS
Infiltration of the skin with which types of cells is seen in SJS/TEN?
1) cytotoxic T lymphocytes
2) NK cells
What are the distinctive pathologic changes of erythema multiforme, as seen in SJS?
subepithelial bullae and subsequent scarring
What is the difference between erythema multiforme major and minor?
Major involves the mucous membranes, while minor does not
What are the primary ocular findings in SJS?
1) mucopurulent conjunctivitis
2) episcleritis
What are the long-term complications of SJS?
1) conjunctival contraction
2) keratinization of the eyelid margins
3) trichiasis
4) tear deficiency
What interventions are used in the acute management of ocular involvement of SJS?
1) lubrication of ocular surface
2) AMT
3) possible use of scleral contact lenses
What is the prognosis of PK in SJS?
very poor
Should eyelid reconstruction be performed prior to or after ocular surface management (LSCT or PK) in SJS?
Eyelid reconstruction should occur prior to long-term ocular surface management
What type of hypersensitiity reaction occurs in Mucous Membrane Pemphigoid (MMP)?
Type II (cytotoxic) – autoantibodies directed against a cell surface antigen (BP180) in the basement membrane zone (BMZ)
What is the gender predilection of MMP?
2:1 female to male
What is the typical demographic of MMP patients?
Women over age 60
What are the 4 main categories within the DDx for MMP?
1) postinfectious condition
2) other autoimmune or hypersensitivity (sarcoid, scleroderma, SJS, lichen planus)
3) prior conjunctival trauma
4) severe blepharoconjunctivitis (AKC, rosacea)
Is MMP typically unilateral or bilateral?
Bilateral, but may be asymmetric
Conjunctival biopsy in patients with suspected MMP can be sent for what tests?
Direct immunofluorescence or immunoperoxidase staining
Which drugs are commonly used in the treatment of MMP?
1) dapsone (mild, non-G6PD deficient)
2) cyclophosphamide (severe)
How is severity of pemphigoid often measured?
1) the amount of shortening of the inferior forniceal depth
2) the extent of symblepharon along the inferior fornix
What are the 2 primary components of ocular surface disease in GVHD?
1) conjunctival inflammation
2) severe dry eye from lacrimal gland infiltration by T lymphocytes
What is a common cause of decreased vision in GVHD other than surface disease?
development of PSC cataract
Filamentary keratitis in severe GVHD can be treated with what type of agent?
Mucolytic, such as acetylcysteine 10%
What is the hallmark feature of Thygeson SPK?
multiple slightly elevated corneal epithelial lesions with negative staining
What is the presumed pathogenesis of Thygeson SPK?
immunogenic of unclear origin
What is the typical management for Thygeson SPK?
1) supportive therapy with lubrication
2) occasionally low-dose steroid (FML) or BCL
What is interstitial keratitis (IK)?
a non-suppurative inflammation of the corneal stroma with cellular infiltrate and vascularization, often caused by a type IV hypsernsitivity reaction to infectious microbes
What is the most common cause of IK?
HSV
What was the first infection to be linked with IK?
late (immune-mediated) sequelae of congenital syphilis
What are the classic non-ocular signs of congenital syphilis?
1) Hutchinson teeth
2) saber shins
3) saddle nose
4) frontal bossing
5) CN VIII deafness
6) cognitive impairment
How is corneal inflamation in syphilitic keratitis treated?
Topical steroids
What is the classic triad of Reiter syndrome?
Ocular, urethral, and joint inflammation
What percent of patients with reactive arthritis are HLA-B27 positive?
> 75%
What is the most common ocular finding in reactive arthritis?
bilateral papillary conjunctivitis with mucopurulent discharge
What are common precursors to the development of reactive arthritis?
1) dysentery due to GNR (Salmonella, Shigella, Yersinia)
2) C trachomatis urethritis
How are corneal infiltrates in reactive arthritis treated?
topical steroids
What are the typical features of Cogan syndrome?
1) stromal keratitis
2) vertigo
3) hearing loss
4) setting of recent URI
With which autoimmune disease is Peripheral Ulcerative Keratitis (PUK) most commonly seen?
rheumatoid arthritis
What is the usual distribution of PUK?
Usually unilateral and limited to 1 sector of the peripheral cornea
What is the pathogenesis of PUK?
Immune-mediated vascular occlusion at the limbus
What is the typical appearance of a lesion in PUK?
lesion in peripheral cornea with absent epithelium with severe stromal thinning
What are the 3 foci of PUK therapy?
1) improve lubrication
2) promote re-epithelialization
3) reduce inflammation
Which collagenase inhibitors have been seen to be effective in treating corneal melt?
1) sodium citrate 10%
2) acetylcysteine solution 20%
3) medroxyprogesterone 1%
4) tetracyclines
What can be done to conjunctiva adjacent to a corneal melt of autoimmune origin?
Recession or excision. These procedures may work through elimination of a source of inflammatory cells and collagenolytic enzymes
What is the cause of Mooren ulcer?
Mooren ulcer, by definition, is of unknown cause. This complicates the identification of an etiology however, which is thought to be related to autoimmunity.
What are potential precipitating factors for Mooren ulcer?
1) trauma
2) surgery
3) prior parasitic infection
How can Mooren ulcer be distinguished from idiopathic PUK?
PUK often involves sclera, while Mooren ulcer does not
What are the 2 clinical forms of Mooren ulcer?
1) one in older patients
2) one in younger patients in Africa, rapidly progressive, often with coexisting parasitemia
What are the features of corneal graft tolerance?
1) absence of blood and lymphatic vessels in the graft and its bed
2) absence of MHC class II-expressing APCs in the graft
3) immunosuppressive characteristics of the aqueous
4) expression of Fas ligand on endothelium
Is episcleritis usually self-limited?
yes
How can episcleritis be differentiated from scleritis?
1) superficial inflammation
2) superficial pain
3) bright red color, as opposed to violaceous color in scleritits
4) blanching of episcleritits with 2.5% topical phenylephrine
What proportion of patients with necrotizing scleritis have an detectable autoimmune disease?
1/3
What is the usual age of onset of scleritis?
4th to 6th decades of life
What are the subtypes of anterior scleritis?
1) diffuse
2) nodular
3) necrotizing (with inflammatory signs vs. scleromalacia perforans)
What are the common features of posterior scleritis?
1) pain
2) proptosis
3) vision loss
4) limitation of motility
5) choroidal folds
6) exudative RD
7) angle-closure
8) lower eyelid retraction
What are the common complications of scleritis?
1) peripheral keratitis (37%)
2) scleral thinning (33%)
3) uveitis (30%)
4) glaucoma (18%)
5) cataract (7%)
What labs are usually included in the initial evaluation of scleritis?
1) CBC w diff
2) ESR/CRP
3) antibody screen (ANA, dsDNA, RF, ANCA)
4) UA
5) serum uric acid
6) RPR
7) CXR
8) ACE/lysozyme
What are the treatments often used in scleritis?
1) mild, anterior: topical steroids
2) moderate, non-necrotizing: oral NSAIDs (ibuprofen 600mg q8h)
3) Severe/necrotizing: anti-TNF drug (infliximab), oral /IV steroids, antimetabolite (methotrexate), cytotoxic agent (cyclophosphamide), immunomodulator (cyclosporine)
What are the types of cells that can form neoplasms of the conjunctiva/cornea?
1) epithelium
2) melanocytes
3) vascular endothelium
4) mesenchymal cells
5) lymphocytes
What are the 3 categories of tumors of the ocular surface epithelium?
1) benign
2) preinvasive
3) malignant
What are the types of benign neoplasms of the ocular surface epithelium?
1) papilloma
2) pseudoepitheliomatous hyperplasia
3) benign hereditary intraepithelial dyskeratosis
What are the types of of preinvasive neoplasms of the ocular surface epithelium?
corneal and conjunctival intraepithelial neoplasia
What are the 2 types of malignant neoplasms of the ocular surface epithelium?
1) squamous cell carcinoma
2) mucoepidermoid carcinoma
What are the 2 forms of conjunctival papilloma?
1) sessile
2) pedunculated
What are signs of dysplasia within a papilloma?
keratinization, symblepharon formation, inflammation, invasion
Where does conjunctival intraepithelial neoplasia (CIN) usually form?
interpalpebral bulbar conj, at or near the limbus
What are the 3 clinical variants of CIN?
1) papilliform
2) gelatinous
3) leukoplakic
Where is squamous cell carcinoma of the conjunctiva/cornea usually seen?
at the limbus within the interpalpebral fissure
Can squamous cell carcinoma of the conj/cornea invade the eye?
Yes, and it can affect the iris/TM and become systemically disseminated
What are the treatment options for CIN and invasive squamous cell carcinoma?
1) surgical excision (+/- cryotherapy)
2) MMC
3) 5-FU
4) IFN-alpha2b
What type of cell is seen to be malignant in addition to epithelial cells in a mucoepidermoid carcinoma?
conjunctival goblet cells
What are the 2 classic types of glandular tumors of the conjunctiva?
1) oncocytoma
2) sebaceous gland carcinoma
From which types of cells does an oncocytoma derive?
ductal and acinar cells of main and accessory lacrimal glands
Sebaceous gland carcinomas can be mistaken for what?
chalazia or chronic unilateral belpharoconjunctivitis
What are the benign tumors arising from conj epithelial melanocytes?
1) freckle
2) benign acquired melanosis
What are the benign tumors arising from conj sub-epithelial melanocytes?
1) ocular melanocytosis
2) blue nevus
3) melanocytoma
What are the benign tumors arising from conj nevus cells?
1) Intraepithelial (junctional) nevus
2) compound nevus
3) subepithelial nevus
What are the benign tumors arising from conj neural cells?
Neurofibroma
Biopsies should be performed for conjunctival nevi seen where?
1) tarsal conj
2) caruncle
3) plica semilunaris
4) fornix
What is the appearance of primary acquired melanosis?
flat, brown lesion of the conjunctival epithelium, usually in an area of sun exposure
What is the overall mortality rate for conjunctival melanoma?
25%
What is the recurrence rate after excision of conjunctival melanoma?
> 50%
What are the hamartomoatous tumors of blood vessels of the eyelid and conj?
1) Nevus flammeus
2) capillary hemangioma
3) cavernous hemangioma
What are the reactive tumors of blood vessels of the eyelid and conj?
1) Pyogenic granuloma
2) Glomus tumor
3) Intravascular papillary endothelial hyperplasia
What are the malignant tumors of blood vessels of the eyelid and conj?
1) Kaposi sarcoma
2) angiosarcoma
What does the presence of diffuse angiomatosis of the palpebral conjunctiva or fornix indicate?
an orbital capillary hemangioma
What is the usual setting in which pyogenic granuloma develops?
in the presence of a chalazion, minor trauma, or surgery, any of which may stimulate an exuberant healing response
What is typical therapy for pyogenic granuloma?
excision with cautery of the base, topical steroids
Which virus is responsible for Kaposi sarcoma?
HHV-8
A Kaposi sarcoma of the conjunctiva may simulate what benign finding?
subconjunctival hemorrhage
What is lymphoid hyperplasia of the conjunctiva?
a benign-appearing accumulation of lymphocytes that may represent a low-grade B-cell lymphoma. It is often indistinguishable from a lymphoma, as both have a “salmon-patch” appearance.
What is the usual patient profile seen in conjunctival lymphoma?
> 50 years old or immunosuppressed
What is cryptopthalmos?
bilateral condition in which the eyelids, eybrows, and lashes fail to form and cornea is merged with epidermis.
What is pseudocryptophthalmos?
formation of the eyes and lids, but with failure of the eyelids to separate
What is microphthalmos?
a small, disorganized globe; it is often associated with trisomies (esp. 13), maternal infection, and toxin or radiation exposure
What is nanophthalmos?
A small, functional eye. The corneal radius of curvature tends to be accordingly small, leading to an excessively steep cornea
What are the dimensions that qualify as microcornea?
<10mm in adult
Are microcorneas usually flat or steep?
usually flat, as opposed to corneas in microphthalmos
What are the dimensions seen in megalocornea?
> 13mm diam in adult, >12mm in newborn
What is posterior embryotoxon?
thickened, anteriorly displaced Schwalbe line (posterior termination of Descemet membrane)
What are the reasons for a cloudy cornea in a newborn?
S -- Sclerocornea T -- Tears in Descemet membrane (traumatic delivery) U -- Ulcer M -- Metabolic conditions (MPS) P -- Posterior corneal defect E -- Endothelial dystrophy D -- Dermoid
Are nanopthalmic eyes usually hyperopic or myopic?
Usually highly hyperopic due to short axial length
What are the systemic associations of microcornea?
1) myotonic dystrophy
2) fetal alcohol syndrome
3) achondroplasia
4) Ehlers-Danlos syndrome
What is the typical inheritance pattern of megalocornea?
X-linked recessive
Is the axial length of an eye with megalocornea usually normal or abnormal?
normal
Patients with isolated cornea plana are usually of what ancestry?
Finnish
What are the anterior segment dysgenesis conditions?
1) posterior embryotoxon
2) Axenfeld-Rieger syndrome
3) Peters anomaly
4) Circumscribed posterior keratoconus
5) Sclerocornea
6) Keratectasia/Congenital anterior staphyloma
Posterior embryotoxon is associated with which syndromes?
1) Alagille syndrome
2) X-linked icthyosis
3) familial aniridia
Where is Schwalbe line usually located?
0.5mm to 2.0mm central to the limbus
What are the features of Axenfeld-Rieger syndrome?
1) posterior embryotoxon
2) iris hypoplasia
3) glaucoma
Mutations in which genes are thought to be responsible for Axenfeld-Reiger syndrome?
Forkhead genes (6p25)
What is Peters anomaly?
A congenital clouding of the central cornea at the site of localized absence of corneal endothelium and Descemet membrane.
What are the two types of Peters anomaly?
I – iridocorneal adhesions
II – cataractous lens or corneolenticular adhesions
What is circumscribed posterior keratoconus?
a localized central/paracentral indentation of the posterior cornea without any protrusion of the anterior surface
Is sclerocornea usually bilateral or unilateral?
90% of cases are bilateral
What are the means through which intrauterine infection can cause ocular damage?
1) direct action
2) teratogenic effect
3) late reactivation
What are the 3 classes of Congenital Corneal Anesthesia?
1) trigeminal anesthesia
2) mesenchymal anomalies (Goldenhar syndrome, Mobius syndrome, familial dysautonomia = Riley-Day syndrome)
3) focal brainstem signs without mesenchymal dysplasia
What is the usual transmission of Riley-Day syndrome (FD)?
autosomal recessive
What is the classic triad of primary congenital glaucoma?
epiphora, photphobia, blepharospasm
What are Haab striae?
tears in Descemet membrane associated with primary congenital glaucoma related to corneal stretching
What is the usual orientation of Haab striae?
Horizontal or concentric with the limbus
What is the usual orientation of striae due to tears in Descemet membrane associated with birth trauma?
Vertical
What is arcus juvenilis?
a deposition of lipid in the peripheral corneal stroma in children or newborns
Mutations of which gene lead to the majority of stromal corneal dystrophies?
TGF-beta-induced gene (TGFBI)
What are the Epithelial corneal dystrophies (per IC3D)?
1) EBMD
2) Mutatino in keratin genes (Meesman)
3) Lisch epithelial
4) Gelatinous droplike
5) Subepithelial mucinous
6) Epithelial recurrent erosion
What are the Bowman Layer dystrophies?
1) Reis-Bucklers
2) Thiel-Behnke
What are the Stromal corneal dystrophies?
1) TGFBI
i) Lattice
ii) Granular
2) Non-TGFBI
i) Macular
ii) Schnyder
iii) Congenital stromal
iv) Fleck
v) Posterior amorphous
vi) Pre-Descemet
What are the Descemet Membrane and Endothleial corneal dystrophies?
1) Fuchs
2) Posterior polymorphous
3) CHED 1
4) CHED 2
What are the histologic findings in EBMD?
1) thickened EBM
2) abnormal epithelial cells with microcysts
3) fibrillar material between basement membrane and Bowman layer
What are the 4 findings of EBMD seen clinically?
1) fingerprint lines
2) map lines (thicker)
3) dots or microcysts
4) cobblestone pattern
How does Meesman (mutation in keratin gene) dystrophy appear clinically?
1) tiny, bubble-like blebs (epithelial vesicles) against the red reflex
2) onset early in life
How does Lisch epithelial corneal dystrophy appear clinically?
1) gray, band-shaped feathery lesions in whorled patterns
2) densely crowded clear microcysts
Gelatinous droplike dystrophy involves subepithelial and stromal deposition of what material?
Amyloid, leading to disruption of epithelial tight junctions and high epithelial permability
What are the 3 clinical appearances of gelatinous droplike corneal dystrophy?
1) Mulberry type
2) Band keratopathy type
3) Kumquat type
How can Reis-Bucklers dystrophy be distinguished from Thiel-Behnke dystrophy histologically?
EM: presence of rod-shaped bodies in R-B vs. curly fibers in T-B
Where are opacities seen clinically in Reis-Bucklers?
Centrally within Bowman layer and superficial stroma
What happens to the Bowman layer in Reis-Bucklers?
Disruption or absence of Bowman layer, with replacement by sheetlike connective tissue with granular Masson-trichrome-red deposits.
What is the clinical appearance of opacities in Thiel-Behnke?
Symmetric subepithelial honeycomb opacities in the central cornea
Is lattice due to gelsolin mutation a true corneal dystrophy?
No, because of systemic involvement (deposition of amyloid)
Where are amyloid deposits most commonly seen in lattice dystrophy?
anterior stroma and occasionally within the subepithelial space
Does lattice dystrophy recur after corneal grafting?
Yes, it can
What is the nature of the material deposited in Granular corneal dystrophy?
Hyaline (stains red with Masson trichrome)
What is the appearance of opacities in granular dystrophy?
Crushed bread crumb-like opacities with:
1) peripheral sparing
2) intervening clear spaces
What is Avellino corneal dystrophy?
It is a combined granular-lattice corneal dystrophy (combination of both of the TGFBI stromal dystrophies). It is also called GCD type 2. It involves both hyaline and amyloid deposits.
Is Macular corneal dystrophy a TGFBI dystrophy?
No (Granular and Lattice are, however)
What is the material deposited in Macular corneal dystrophy?
mucopolysaccharide (stains with Alcian blue or colloidal iron)
What is the inheritance of Macular corneal dystrophy?
AR
Are there intervening clear spaces or peripheral sparing in Macular corneal dystrophy?
No
What is the material deposited in Schnyder corneal dystrophy?
cholesterol and phospholipids
What stain can be used to identify phospholipids?
Oil red O (stains phospholipids red)
What are the clinical features of Schnyder corneal dystrophy?
1) central corneal opacification +/- subepithelial cyrstals
2) dense corneal arcus lipoides
3) midperipheral corneal opacification
4) decreased corneal sensation
What are the clinical features of congenital stromal corneal dystrophy?
1) congenital diffuse, bilateral corneal clouding
2) flakelike, whitish opacities throughout the stroma
3) thickened corneas
Is vision usually decreased in Fleck corneal dystrophy?
No
What substances are deposited in Fleck corneal dystrophy?
GAGs and lipids
Is the gray posterior stromal opacity of Posterior amorphous corneal dystrophy focal or diffuse?
Diffuse and sheet-like (as opposed to Pre-Descemet corneal dystrophy, which involves focal gray posterior stromal opacities)
What are the two primary features of endothelial cells in Fuchs endothelial dystrophy?
1) polymegathism
2) polymorphism
Where are corneal guttae seen first in Fuchs endothelial dystrophy?
centrally (later peripherally)
What is the usual age of presentation of Fuchs endothelial dystrophy?
5th or 6th decade, except in the early-onset form (3rd decade)
Why are symptoms in Fuchs endothelial dystrophy often worse upon awakening?
reduction in evaporative losses of stromal fluid during sleep
What features indicate the potential for corneal decompensation with intraocular surgery in Fuchs dystrophy?
1) endothelial cell density < 1000/mm^2
2) CCT > 640 microns
3) presence of epithelial edema
What is the histologic abnormality seen in Posterior Polymorphous corneal dystrophy?
Abnormal, multilayered endothelial cells that look and behave like epithelial cells or fibroblasts
What are the abnormal features of endothelial cells in PPMD?
1) microvili
2) positive staining for keratin
3) rapid growth in cell culture
4) intercellular desmosomes
How can posterior polymorphous dystrophy be distinguished from ICE?
ICE is sporadic and almost always unilateral, as opposed to PPMD, which is inherited in AD fashion and bilateral
What are the clinical findings of PPMD?
1) isolated grouped vesicles
2) geographic, discrete, gray lesions
3) broad bands with scalloped edges
What is seen histologically in CHED?
1) thickened, laminated Descemet membrane
2) sparse, atrophic endothelial cells
3) replacement of patches of endothelium with keratinized stratified squamous epithelium (CHED 1)
Is the corneal clouding more severe in CHED 2 or CHED 1?
CHED 2
What is the prevalence of keratoconus?
1 in 2000
What are risk factors for keratoconus?
1) family history
2) eye rubbing
3) atopy
4) hard contact lens wear
5) oxidative stress
What are the histologic features of keratoconus?
1) fragmentation of Bowman layer
2) thinning of stroma and epithelium
3) folds or breaks in Descemet membrane
4) variable amounts of scarring
What are the clinical signs of keratoconus?
1) Rizzutti sign – conical reflection on nasal cornea when light is shown from temporal side
2) Munson sign
3) Fleishcer ring – iron line within epithelium around base of the cone
4) Vogt striae – stress lines within posterior stroma
What precipitates acute hydrops?
a tear in Descemet membrane, leading to sudden development of corneal edema
How long does a break in Descemet membrane take to heal spontaneously?
6-12 weeks
What are disease/syndrome associations with keratoconus?
1) Down syndrome
2) atopy
3) Marfan syndrome
4) Floppy eyelid syndrome
5) LHON
6) Mitral valve prolapse
Where is the steepening in keratoconus?
inferior cornea
Where is the thinning in keratoconus?
near the visual axis, at the apex of the protrusion
What are indications for corneal transplatnation in keratoconus?
1) contact lens intolerance
2) poor vision with a good contact lens fit (usually due to apical scarring)
3) unstable contact lens fit
4) progressive thinning to the periphery, which would require a large graft (higher risk)
What are the advantages of DALK over PK for keratoconus?
1) lower likelihood of rejection by not implanting donor endothelium
2) better wound integrity
Where is the thinning seen in pellucid marginal degeneration?
at the inferior periphery of the cornea (protrusion occurs above the thinning
Is the prognosis for PK in pellucid marginal better or worse than that for keratoconus?
Worse for pellucid marginal due to the location of the graft
What is the onset of keratoglobus?
congenital
Where is the thinning in keratoglobus?
Mid-periphery of cornea and diffuse
Which is the only Mucopolysaccaridosis (MPS) syndrome that is not autosomal recessive?
Hunter syndrome (X-linked)
What are the 3 MPS-I syndromes?
Hurler, Scheie, Hurler-Scheie
What are the ophthalmic manifestations of most MPS syndromes?
1) corneal clouding (centripetal)
2) retinopathy
3) optic atrophy
What are clinical changes seen in corneas of diabetics?
epithelial erosions, abnormalities of epithelial-stromal adhesion, and hypoesthesia
What can corneal arcus in a patient < 40 years old indicate?
Lipid abnormality
What are the 3 corenea-affecting hypolipoproteinemias?
1) LCAT deficiency
2) Tangier disease
3) Fish eye disease
What are the corneal findings that can be seen in hypolipoproteinemias?
1) diffuse clouding
2) focal posterior stromal opacities
What are the 4 sphingolipidoses that affect the cornea?
1) Fabry disease
2) multiple sulfatase deficiency
3) Generalized gangliosidosis
4) Tay Sachs disease
What are the ocular findings in sphingolipidoses?
1) cornea verticillata in the basal epithelium (resemble amiodorone or chloroquine therapy changes)
2) periorbital edema
3) posterior spokelike cataracts
4) conjunctival aneurysms
What corneal finding is seen in the mucolipidoses?
Corneal clouding
What are the corneal findings in cystinosis?
fine polychromatic cystine crystals in the anterior stroma, mostly peripheral, but can extend centrally
What is the management of corneal cystinosis?
topical cysteamine drops
What are the ocular findings in tryosinemia?
1) recurrent pseudodendrites
2) corneal vascularization and scarring
3) conjunctival injection
4) tarsal papillary hypertrophy
What is the management of tyrosinemia?
Dietary restriction of tyrosine and phenylalanine
What are the corneal findings in alkaptonuria?
Darkly pigmented dot-like opacities in the corneal epithelium or in the Bowman layer near the limbus
What are the diagnostic characteristics of amyloid?
1) positive staining with Congo red dye
2) apple green birefringence with Congo red
3) metachromasia with crystal violet dye
4) fluorescence in UV light with thioflavine T stain
5) dichroism
6) typical filamentous appearance on EM
What are the ophthalmic findings in disorders of excess immunoglobulin synthesis (MM, WM, MGUS)?
1) crystalline deposition in all layers of cornea (scintillating, polychromatic)
2) copper deposition in cornea
3) sludging of blood flow in cornea/conj
4) pars plana proteinaceous cysts
5) infiltration of sclera
6) orbital bony invasion with proptosis
What corneal findings can be seen in gout?
epithelial and stromal deposits in the absence of inflammation. Rarely, orange-brown band keratopahy or white band keratopathy can be seen
What ophthalmic findings are seen in porphyria?
1) interpalpebral conj injection
2) conj vesicles, necrosis, scarring
3) symblepharon micmicking bullous pemphigoid
4) necrotizing scleritis
5) corneal thinning at the limbus
What are the possible colors of a Kayser-Fleischer ring in Wilson disease?
1) golden brown
2) red
3) green
In which layer of the cornea does copper deposition occur in Wilson disease?
posterior Descemet membrane
What is the gold standard for diagnosis of Wilson disease?
liver biopsy
Enlarged corneal nerves are seen in which of the MEN syndromes?
MEN 2B (medullary carcinoma of the thyroid, pheochromocytoma, mucosal neuromas)
Which conditions demonstrate enlarged corneal nerves?
1) MEN 2B
2) Refusm syndrome
3) leprosy
4) Riley-Day syndrome (familial dysautonomia)
5) Neurofibromatous
6) Acanthamoeba perineuritis
Is the prevalence of pterygia associated with proximity to the equator?
Yes
What type of iron line can be seen at the leading edge of a pterygium?
Stocker line
What are indications for excision of a pterygium?
1) approach of the visual axis
2) rapid growth
3) chronic irritation
4) cosmetically unacceptable
5) astigmatism
What do conjunctival concretions contain?
epithelial and keratin debris
What is conjunctivochalasis?
poor adherence of the bulbar conjunctiva
What are the nautral age-related changes of the cornea?
1) flattening in the vertical meridian
2) thinning
3) decrease in transparency
4) thickening of Descemet membrane
5) peripheral endothelial guttae (Hassall-Henle bodies)
6) reduction in endothelial cell density (0.6%/year)
What is a Coats white ring?
circle or oval-shaped area of discrete gray-white dots seen in superficial stroma (represents iron-containing fibrotic remnants of metallic foreign body)
What is a Hudson-Stahli line?
horizontal iron line located between the lower and middle thirds of the cornea (nearly ubiquitous with aging)
What is a Ferry line?
an iron line in the corneal epithelium anterior to a filtering bleb
In which layer is calcium deposited in band keratopathy?
Bowman layer
What are risk factors for development of band keratopahy?
1) chronic ocular inflammation
2) hypercalcemia
3) hyperphosphatemia
4) hereditary transmission
5) exposure to mercurial vapors
6) silicone oil in an aphakic eye or in the AC
What is used to remove calcium from Bowman layer in band keratopathy?
EDTA
What is the white limbal girdle of Vogt?
a stromal degeneration involving elastotic degeneration of collagen, sometimes with particles of calcium
What is arcus senilis?
a deposition of lipid in the peripheral corneal stroma, usually starting inferiorly
What can unilateral arcus indicate?
1) contralateral carotid disease
2) hypotony
What is anterior crocodile shagreen?
a central bilateral corneal opacity at the level of Bowman layer characterized by polygonal gray opacities separated by clear zones
What is the usual spread of Terrien marginal degeneration?
Starts superiorly, spreads circumferentially
What are the clinical features of Terrien marginal degeneration?
1) unilateral or asymmetrically bilateral
2) slowly progressive thinning of peripheral cornea
3) line of lipid deposits at leading edge of thinning
4) development of flattening superiorly (against the rule astigmatism)
What is a Salzmann nodule?
A late sequela to old, long-term keratitis. A Salzmann nodule is gray-white or blue-white and elevated, often located in central or paracentral cornea and associated with pannus
What is lipid keratopathy?
Deposition of lipid in the corneal stroma, usually in the setting of prior vascularization of the cornea
What are the three iridocorneal endothelial syndromes?
1) Iris nevus syndrome
2) Cogan Reese
3) Essential Iris atrophy
What are the clinical features of the ICE syndromes?
1) iris changes (corectopia, iris atrophy)
2) abnormal corneal endothelium (takes on characteristics of epithelial cells)
3) PAS
What are the drugs most commonly associated with cornea verticillata?
1) amiodarone
2) chloroquine
3) hydroxychloroquine
4) indomethacin
5) phenothiazines
Which class of metabolic disorders can present with cornea verticillata?
Sphingolipidoses (including Fabry disease)
What is the appearance of ciprofloxacin deposits?
chalky white precipitate composed of ciprofloxacin crystals within an epithelial defect
What is adrenochrome?
an oxidation product of epinephrine, which can accumulate in conjunctival cysts with long-term therapy with epinephrine compounds, tetracycline, or minocycline
Pigmentation of the endothelium, Descemet membrane, and posterior stroma are seen with which drug?
Chlorpromazine
What are the objectives of therapy for burns caused by heat?
1) relieve discomfort
2) prevent inflammation, ulceration, perforation,
3) minimize eyelid scarring
What surgical methods can be used to treat recurrent epithelial breakdown?
1) conjunctival flap
2) AMT
3) LSCT
4) mucous membrane graft
What are common alkaline agents causing ocular surface burns?
detergents, ammonia, bleach, oven cleaners, fertilizers, pesticides, lye
Why do alkaline substances tend to penetrate the cornea deeper than acidic substances?
Alkaline substances cause saponification of fatty acids in cell membranes, which results in cellular disruption and epithelial penetration. Acids precipitate proteins they contact, creating a barrier to penetration.
Should necrotic epithelium be debrided in a corneal burn?
Yes, to minimize the release of inflammatory mediators produced by damaged epithelial cells and promote re-epithelialization.
How soon after corneal burn can limbal stem cell transplantation be performed
as soon as 2 weeks after injury
What kind of conjunctival reaction is seen in toxic conjunctivitis?
Can be either papillary or follicular
Effacement of the palisades of Vogt indicates what?
Limbal stem cell deficiency
Which drugs are most commonly associated with a follicular conjunctivitis?
1) atropine
2) antivirals
3) miotics
4) sulfonamides
5) epinephrin
6) apraclonidine
7) alpha-2 agonists
8) vasoconstrictors
What is drug-induced cicatricial pemphigoid?
long-term topical drug use leading to insidiously progressive subconjunctival scarring that can lead to contraction of the conjunctival fornix, symblepharon, and corneal pannus formation.
The dieffenbachia plant is known to cause deposition of what type of crystals in the cornea?
calcium oxalate
What is iridodialysis?
Separation of the iris root from the ciliary body
What is cyclodialysis?
separation of the ciliary body from its attachment to the scleral spur
What can result from a cyclodialysis cleft?
1) increase in uveoscleral outflow
2) aqueous hyposecretion
These two lead to hypotony and macular edema
What conditions are associated with spontaneous hyphema in children?
1) juvenile xanthogranuloma
2) retinoblastoma
3) leukemia
What conditions are associated with spontaneous hyphema in adults?
1) rubeosis iridis
2) clotting abnormalities
3) herpetic disease
4) IOL problems
What is the reported incidence of rebleeding after traumatic hyphema?
5%
What is the time frame after hyphema within which rebleeding is most likely to occur?
3-7 days
What are complications associated with rebleeding after hyphema?
1) glaucoma
2) optic atrophy
3) corneal blood staining
What are the basic aspects of treatment of traumatic hyphema?
1) control of IOP
2) protective shield over eye
3) restriction of physical activity
4) elevation of head of bed
5) daily observation
6) steroids and cycloplegics if there is concern for iritis
7) pain control with non-NSAID medications
What are the 3 general classes of indications for surgical intervention in traumatic hyphema?
1) to prevent optic atrophy (glaucomatous damage)
2) to prevent corneal blood staining
3) to prevent PAS
How do the indications for surgical intervention in traumatic hyphema differ for preventing optic atrophy in patients with and without sickle cell hemoglobinopathy?
With sickle hemoglobinopathy:
IOP >= 25 for 24 hours or repeated episodes of IOP > 30 over 2-4 days
Without sickle hemoglobinopathy:
IOP > 60mm x 2 days of IOP > 35 x 7 days
What is the indication for surgical intervention to prevent corneal blood staining in traumatic hyphema?
IOP > 25 x 5 days with evidence of early corneal blood staining
What is the indication for surgical intervention to prevent PAS in traumatic hyphema?
Total hyphema x 5 days or any hyphema failing to resolve to a volume of less than 50% after 8 days
Which agents are contraindicated in sickle cell patients with traumatic hyphema?
1) Carbonic anhydrase inhibitors (lower pH of AC –> greater sickling)
2) Osmotic diuretics (hemoconcentration –> greater sickling)
How quickly does a rust ring begin to form around a iron foreign body in the cornea?
within a few hours
Corneal abrasions due to which types of injuries are most likely to result recurrent erosions?
1) fingernail
2) paper edge
What is the difference between a penetrating injury and a perforating injury?
A penetrating injury involves only an entrance wound.
A perforating injury involves both an entrance wound and an exit wound.
What temporizing measures can be taken preoperatively for a patient identified to have an open globe?
1) protective shield
2) avoid opening of the eyelids as much as possible
3) make patient NPO
4) pain control
5) antiemesis
6) IV antibiotics
7) tetanus prophylaxis
What is the longest enucleation should be delayed for a traumatic open globe injury in which restoration of the anatomy is not possible?
12-14 days. After this time, the risk of sympathetic ophthalmia rises.
Why is retrobulbar or peribulbar anesthetic injection usually avoided in surgery to repair an open globe injury?
Retrobulbar or peribulbar injection increases orbital pressure, increasing risk of expulsion of intraocular contents.
If vitreous has prolapsed through an corneal wound, where should it be cut?
Flush with the cornea
What is the McCannel technique?
A surgical technique with which an iris laceration can be repaired. It involves using a 10-0 polypropylene suture with long needles that can be passed transcamerally.
How many days after total corneal debridement (as may occur during vitrectomy or as occurs in PRK) is a normal corneal surface first seen?
5 days
What are common indications for conjunctival autograft?
1) Pterygium surgery
2) cicatricial strabismus
3) fornix reconstruction
4) repair after excision of conjunctival tumor
5) symblepharon repair
What are common indications for limbal autograft or allograft?
1) Chemical injury
2) Thermal burn
3) Contact lens keratopathy
4) persistent epithelial defect
5) Post-surgical limbal depletion
6) Chronic medication toxicity
7) SJS
8) Mucous membrane pemphigoid
9) Aniridia
10) Atopy
What are common indications for amniotic membrane or mucous membrane transplant?
1) fornix reconstruction
2) chemical injury
3) immune melts
4) pterygium surgery
5) SJS
6) Mucous membrane pemphigoid
7) Repair after excision of conjunctival tumor
What were the top two indications for PK in recent years?
1) Keratoconus – 20-22%
2) Repeat PK (graft failure) – 12-18%
What is the most common indication for endothelial keratoplasty (EK)?
Fuchs endothelial dystrophy
What is the most common indication for DALK?
Keratoconus
How often should BCLs be replaced?
every 2-4 weeks, or as deposits accumulate on the lens
What can be done to speed polymerization and smooth the surface of cyanoacrylate when gluing a cornea?
place a drop of viscoelastic on the cyanoacrylate
How long can a corneal button be stored while maintaining viability?
2 weeks with current methods.
What are the components of commonly used corneal button storage media?
1) chondroitin sulfate
2) dextran
3) ascorbic acid
4) vitamin B12
5) ATP precursors
6) gentamicin
7) streptomycin
What is a commonly used cutoff for endothelial cell count in a donor cornea?
2000 cells/mm^2
To what depth in the cornea can PTK treat disease/opacities?
up to 75 microns
To what depth in the cornea can Superficial Anterior Lamellar Keratoplasty (SALK) treat disease/opacities?
1/3 corneal depth
To what depth in the cornea can DALK treat disease/opacities?
up to posterior stroma
What are factors that decrease the likelihood of success of a proposed corneal transplant?
1) deep corneal vascularization
2) peripheral corneal thinning
3) previous graft failures
4) Increased IOP
5) active anterior segment inflammation
Shallow AC and low pressure associated with wound leak after PK for more than how many days indicate need for resuturing?
3 days
What are complications associated with sutures in a PK?
1) irregular astigmatism
2) cheese wiring
3) breakage
4) infectious abscess (often around an exposed or broken suture)
5) noninfectious suture infiltrate
6) GPC from exposed knots
7) vascularization along suture tracks
Can severe astigmatism result in monocular diplopia?
Yes
Do most episodes of corneal graft rejection cause irreversible graft failure?
If recognized early and treated aggressively with steroids, no.
What are the 4 clinical forms of corneal graft rejection?
1) Epithelial rejection (10%)
2) Subepithelial rejection
3) Stromal rejection
4) Endothelial rejection (10-37%)
What is the most common form of corneal graft rejection?
Endothelial rejection (up to 37%)
Does corneal graft rejection frequently happen within the first month after surgery?
No
What are the forms that endothelial rejection can take?
1) clumps of inflammatory precipitates
2) Khodadoust line – linear pattern of inflammatory precipitates underneath an area of corneal edema
Why is endothelial rejection of a corneal graft particularly serious?
Endothelial cell loss can lead to stromal and epithelial edema, and ultimately graft failure.
Corneal transplant in children less than 2 years of age is associated with what?
Rapid neovascularization, especially along sutures.
What is a rotational autograft?
The use of eccentric trephination and rotation of the host corneal button to reposition a localized corneal opacity that involves the visual axis.
What are the two classifications of patients who are considered for keratoprosthesis?
Type 1 – Patients with good blink reflex, wet eye
Type 2 – Patients with significant conjunctival scarring, dry eye, exposure
What are the most common complications of keratoprosthesis?
1) Retroprosthetic membrane (24.8%)
2) high IOP (14.8%)
3) vitritis (4.9%)
4) retinal detachment (3.5%)
What is the retention rate of the Type I KPro at 19 months?
83%
What is the currently the most common method of isolating Descemet membrane for DALK?
Anwar big-bubble technique
Is 20 microns of residual stromal tissue after DALK visually significant?
No, but 80 microns of residual stroma has been shown to be visually significant
What are possible complications of DALK?
1) double anterior chamber / Descemet detachment
2) opacification and vascularization of the interface
3) rejection
4) inflammatory necrosis of the graft
What are the basic steps of the Anwar big-bubble technique for DALK?
1) deep trephination (at least 300 microns)
2) tunneling 2-3mm into paracentral corneal stroma
3) air injection into pre-Descemet plane
4) limbal paracentesis
5) dissection of stroma
For which conditions is DSEK most commonly performed?
1) Fuchs endothelial dystrophy
2) PBK
3) Failed corneal graft
4) ICE
5) PPMD
6) CHED
What is the rate of graft dislocation in DSEK with experienced surgeons?
4%
Is epithelial ingrowth after DSEK a negative prognostic factor?
No, unlike epithelial ingrowth in cataract extraction or PK. In DSEK, epithelial ingrowth is benign and can be observed.
What is the typical range of BCVA after DSEK?
20/25 to 20/40
What are the potential complications of DSEK?
1) decreased BCVA
2) cataract progression
3) primary graft failure
4) graft rejection
5) endothelial cell loss
What is the mean percentage of endothelial cell loss 5 years after DSEK?
53%
What is the difference between DSEK and DMEK?
DSEK grafts include posterior corneal stroma, while DMEK grafts contain only Descemet membrane and endothelium
Does Descemet membrane endothelial transplant (DMET) work in patients with PBK?
No, but it does appear to work in Fuchs dystrophy. This is thought to be related to need for disruption of abnormal Descemet membrane. It may also work in PPMD, which also involves an abnormal Descemet membrane
What is involved in Descemet membrane endothelial transplant (DMET)?
Descemetorrhexis followed by implantation of a free-floating donor graft of Descemet membrane and endothelial cells
