Cornea Flashcards
If a positive response is not seen in 1-2 days of treating a corneal dellen with aggressive lubrication what might be considered for treatment?
Surgical revision or resection of the offending tissue (elevated limbal or conj lesion)
- pressure patching
A ____ is an area of focal stromal desiccation and thinning, characteristically in the absence of a frank epi defect
A corneal dellen
Terrien marginal degeneration: is a noninflammatory, slowly progressive thinning of the peripheral cornea, is it usually bilateral or unilateral?
Bilateral, but can be asymmetric
T = Two - both eyes
Terrien marginal degeneration: initially presents where on the cornea?
Superonasal area, peripherally, then spreads circumferentialy
(T = top)
Terrien marginal degeneration: Are affected patients usually symptomatic?
Usually asymptomatic until thinning results in increased astigmatism and subsequent reduction in vision (causes steepening of the surface 90 degrees away from thinned area)
(T = Tolerable)
Terrien marginal degeneration: Is there a K epi defect?
K epithelium remains inTact
T = inTact - no epi defect
Terrien marginal degeneration: what traverses the area of stromal thinning? What is seen at the leading edge of the thinning?
- Fine pannus traverses the area of stromal thinning
- A line of lipid deposits appears at the leading edge of the pannus (lipid keratopathy)
(T = Traverses)
An inflammatory condition of the peripheral cornea that resembles Terrien marginal degeneration but occurs in children and young adults is called _____
Fuchs superficial marginal keratitis
Terriens occurs typically in those older than 40 yrs age
What is the MC complication of a conjunctival flap?
Retraction of the flap - occurs in about 10% of cases. Surgeon should take care to minimize tension on any conj flap when placed
(hemorrhage beneath the flap and formation of epi inclusion cysts are less common)
What are the indications for a conjunctival flap?
- Chronic, sterile, nonhealing epi defect
- Closed but unstable corneal wounds
- Painful bullous keratopathy in a pt who is a poor candidate for PK
- Pthisical eye being prepared for a prosthetic shell
Superior conjunctival inflammation is characteristic of what disorders?
SLK, Floppy eyelid syndrome, giant papillary conjunctivitis, and trachoma
In a patient with superior conj inflammation, how might you differentiate SLK from floppy eyelid syndrome?
FES will be a/w eyelids that are everted with minimal effort
What test might be helpful in assessing risk factors for a patient with SLK?
Thyroid function tests
- SLK is a/w thyroid dysfunction
SLK is a chronic, recurrent inflammatory condition involving the superior tarsal and bulbar conj, superior limbus and K: what is the supposed etiology?
SLK is 2/2 mechanical trauma from the upper eyelid to the superior bulbar and tarsal conj.
- A/w autoimmune thyroid dz, graft-vs-host dz, s/p blepharoplasty
SLK: bilateral or unilateral?
Age? Gender? is vision affected?
SLK: 1. Often BILATERAL but can be asymmetric.
- Women 20-70 yrs age
- Vision usually unaffected
SLK: what are the ocular findings?
- fine papillary reaction on the sup tarsal conj
- Injection and thickening of the sup bulbar conj
- Hypertrophy of sup limbus
- fine PEE of bulbar conj and sup cornea just below limbus
- Sup filamentary keratitis
SLK must be differentiated from CLK - what characteristics separate CLK from SLK?
CLK: 2/2 focal limbal stem cell deficiency
- Vision may be impaired by PEE extending into visual axis
- Filamentary keratitis does not typically occur
SLK: what are the treatment options? and what treatment is most effective?
- Surgical treatment tends to be more effective
- Surgical options include - thermocauterization of the sup bulbar conj, resection of sup limbal bulbar conj, amniotic membrane transplantation, conj fixation sutures
- Medical options - topical anti-inflammatory agents, topical cyclosporine, autologous serum drops, large-diameter BCL
When culturing corneal ulcers, what medium is suitable for culturing fungi?
- Sabouraud dextrose agar
- Blood agar
- Brain-heart infusion
When culturing corneal ulcers, what medium is suitable for culturing aerobic bacteria?
- Chocolate agar
2. Thioglycollate broth (for aerobes and anaerobes)
When culturing corneal ulcers, what medium is suitable for culturing anaerobic bacteria?
- Thioglycollate broth (for both aerobes and anaerobes)
When culturing corneal ulcers, what medium is suitable for culturing mycobacteria?
Lowenstein-Jensen medium
What components make up the lacrimal functional unit?
- Lacrimal glands
- Ocular surface (K, conj, limbus)
- Eyelids
- Sensory and motor nerves connecting these components
In aqueous tear deficiency, what type of cell causes inflammation of the lacrimal glands which leads to diminished tear production and propagation of inflammatory mediators such as TNF-alpha and IL-1?
T-cell mediated inflammation of the lacrimal gland –> aqueous tear deficiency
What is the primary abnormality in Evaporative dry eye?
MGD
Tear film instability may occur 2/2 aqueous tear deficiency, evaporative dry eye, xerophthalmia, allergy, CL wear, smoking, DM, use of video displays, long-term use of meds with topical preservatives - what about dietary fatty acids?
A high ratio of dietary n-6 to n-3 essential fatty acids is a/w tear film instability
What are the clinical findings of MGD?
- meibomian gland orifices may pout or show metaplasia w/ turbid/viscous/cheesy secretions
- posterior lid margins are often irregular w/ prominent, telangiectatic blood vessels
- Foam in the tear meniscus along the lower lid, bulbar and tarsal conj injection, papillary rxn on the inf tarsus
- Often a/w rosacea
In infectious crystalline keratopathy, which is occasionally seen in grafts and other immunocompromised corneas, branching colonies of organisms proliferate in K stroma with minimal inflammatory response. What organism is the most common causative for this condition?
Streptococcus viridans
What is the best non-invasive way to visualize cysts pathognomonic of Acanthamoeba keratitis?
Confocal microscopy
What condition is a/w the JAG1 gene?
Alagille syndrome (autosomal dominant) - "JAGuars are dominant" (Heart defects, liver dysfunction, posterior embryotoxon, pigmentary retinopathy)
What ocular findings are seen in Alagille syndrome?
What non-ocular findings are seen?
Heart defects, liver dysfunction, posterior embryotoxon, pigmentary retinopathy
What condition is PITX2 a/w?
Axenfeld-Reiger
What condition is a/w PAX6?
Aniridia
What condition is a/w OPTN?
Normal tension glaucoma
Rose bengal and lissamine green stain epithelial cells of the K when ________…?
When a disruption occurs in the protective mucin coating
Corneal graft edema with an intact epithelium is most indicative of what ?
Graft rejection
- look for a Khodadoust line (linear collection of inflammatory precipitates on the endothelium)
What is another name for vortex keratopathy?
cornea verticillata
A cornea has a whorl-like pattern of golden brown or gray deposits on the inferior interpalpebral aspect. What is the likely diagnosis?
Cornea verticillata
What is the most common cause of cornea verticillata?
What is the treatment?
- Amiodarone
2. Usually asymptomatic so treatment not needed
What staining techniques are useful in cases of suspected fungal infection?
- KOH,
- Gram stain,
- Giemsa stain,
- Gomori-methenamine silver,
- acridine orange,
- calcofluor white
What culture media are used for acanthamoeba?
- Non-nutrient agar with bacterial overlay
- Blood agar
- Buffered charcoal-yeast extract agar
Neisseria is a gram negative diplococcus normally seen inside neutrophils on a smear with what stain?
It grows on what agar?
- Gram stain
- Chocolate agar
- May be detected by PCR
Chlamydia is an obligate intracellular parasite and is best detected with what stain?
- Giemsa stain
2. Also detected via immunofluorescent antibody tests or by PCR
