Cornea (pt 3, Infectious/Viral Conditions)

Viral keratitis

Caused by herpes simplex or zoster

Both are dormant in neural ganglion after primary infection

Ocular signs → Virus is dormant in trigeminal ganglion

Herpes simplex keratitis

Primary infection usually mimics upper resp infection and isn’t detected

Triggered by UV, stress, illness, eye surgery/trauma

Layers of the cornea that herpes simplex affects

Epithelium → Dendrites

Stroma → Immune response or necrotic

Endothelial → Endotheliitis or disciform keratitis

Dendritic herpes simplex keratitis

Live virus is replicating

Dendritic herpes simplex keratitis clinical findings

• Swollen epithelial cells in a individual or stellate pattern (day 1-3)

• Dendritic epithelial lesion (day 4 until resolution)

• Follicular rxn

• Ant chamb rxn

• Reduced corneal sensitivity

• Lid lesions may or may not be seen

• Elevated IOP

Why is the IOP elevated during dendritic herpes simplex keratitis

Trabeculitis

TM is inflamed and not working well for aq outflow

Terminal bulb

Herpes simplex virus is killing cells as it expands (does not occur in zoster)

Bright band of cells at edge of lesion

Dendritic herpes simplex keratitis complications

• Corneal scarring

• Geographic ulcer (medically induced)

• Neurotrophic keratitis

Dendritic herpes simplex keratitis Tx

• Topical antiviral

• Oral antiviral

• Topical cycloplegic

• Topical steroid: ONLY after epithelium heals, do not use on active virus

Geographic ulcer

Enlargement of dendritic ulcer after use of topical steroids

Neurotrophic keratitis

Cornea loses trigeminal nerve innervation → Corneal feels nothing → No stimulation to re-epithelialize after damage

Seen with dendritic herpes simplex keratitis, herpes zoster, OSD, diabetes, or topical medication toxicity

Neurotrophic keratitis stages

1: Epithelial irregularities and PEEs (misdiagnosed as OSD)

2: Persistent defects with stromal involvement

3: Corneal ulceration with stromal melting (emergency)

Neurotropic keratitis clinical findings

• Decreased corneal sensation

• Decreased tear film stability

Neurotrophic keratitis complications

Corneal perforation

Stage 1 neurotrophic keratitis Tx

• Preservative free artificial tears

• Autologous serum

• Punctal occlusion or moisture chamber goggles (keep tears on eye)

Stage 2 neurotrophic keratitis Tx

• Cenegermin

• Amniotic membrane

• Scleral or bandage CL

• Tarsorrhaphy (sew lids shut)

Cenegermin

Oxervate, drop

Promotes corneal nerve growth

Stage 3 neurotrophic keratitis Tx

• Amniotic membrane

• Advanced corneal surgery

• Oxervate

Epithelial (dendritic) keratitis hallmark findings

Dendrite ulcer with positive staining of terminal end bulbs

Immune/Interstitial herpes simplex keratitis

No live virus, cornea inflammatory reaction to virus antigen

Immune herpes simplex keratitis clinical findings

• Deep stromal infiltrates

• Intact epithelium

• Ant chamb rxn

• Increase in IOP (trabeculitis)

Immune herpes simplex keratitis complications

Corneal neovascularization and scarring

Immune herpes simplex keratitis Tx

• Topical steroid drop

• Oral antiviral medication

• Topical cycloplegic

Immune stromal hallmark findings

Deep stromal infiltrates with intact epithelium

Necrotizing herpes simplex keratitis

Live virus, damages tissue

More aggressive form of stromal herpes keratitis

Necrotizing herpes simplex keratitis clinical findings

• Deep stromal infiltrates

• Epithelial defect

• Significant ant chamb rxn with hypopyon

• Increase in IOP

Necrotizing herpes simplex keratitis complications

Corneal scarring and perforation

Necrotizing herpes simplex keratitis Tx

• Topical antiviral drop

• Oral antiviral medication (prevent reactivation)

• Topical cycloplegic

• PK if perforation occurs

Necrotizing stromal keratitis hallmark findings

Deep stromal infiltrates with epithelial defects

Herpes simplex endotheliitis (disciform) keratitis

No live virus, cornea inflammatory reaction to virus antigen

Herpes simplex endotheliitis keratitis clinical findings

• Intact epithelium

• Disc shaped stromal edema (endotheliitis, can’t pump out fluid)

• Wessely ring

• Granulomatous cells and flare: Large cells and flare that will precipitate and stick to cornea

• Increased IOP

Wessely ring

Circular immune mediated stromal infiltrate seen in herpes simplex endotheliitis keratitis

How to tell herpes simplex endotheliitis keratitis from acanthameoba

Pain with acanthamoeba

Herpes simplex endotheliitis (disciform) keratitis complications

• Corneal scarring and neovascularization

• Secondary glaucoma

Herpes simplex endotheliitis (disciform) keratitis Tx

• Topical steroid

• Oral or topical antiviral (prophylactic)

• Topical cycloplegic

Endotheliitis (disciform) keratitis hallmark findings

Disc shaped stromal edema

Herpes zoster ophthalmicus

Caused by varicella zoster and seen in old or immunocompromised pts

Presentations follow a specific order

Live virus present in skin

Herpes zoster opthalmicus presentation order

Prodromal phase → Maculopapular rash → Epithelial keratitis → Nummular keratitis → Stromal keratitis

Prodromal phase

3-5 days prior to rash

Complain of malaise and fatigue

Affected dermatome will have itching, tingling, or burning sensation (24 hrs before rash)

Maculopapular rash phase

Vesicles appear that will respect the midline and lid edema

Vesicles on nose (Hutchinson sign) → Ocular involvement

Epithelial keratitis phase

Occurs 2-3 days after rash onset and will spontaneously resolve

Pseudo-dendrite appearance except no terminal bulbs

Nummular keratitis phase

Occurs 10 days after rash onset, develops at site of pseudo-dendrites

Appears as subepithelial granular deposits with stromal haze

Stromal (interstitial) keratitis

Occurs 3 weeks after rash onset

Deep infiltrates with intact epithelium

Herpes zoster ophthalmicus additional clinical findings

• Conjunctivitis: Follicular, pseudomembrane or membrane, more common with eyelid margin vesicles

• Episcleritis: Occurs at onset of rash

• Disciform keratitis (less common)

Herpes zoster ophthalmicus complications

• Mucus plaques: Elevated plaques that occur 3-6 months after rash onset, scars if left untreated

• Neurotrophic keratopathy: Persistent epithelial defects coalesce into ulcer, pt denies pain

• Post-herpetic neuralgia: Persistent pain after rash resolution, pain worse at night or aggravated by touch

Herpes zoster ophthalmicus Tx for macupapular rash

• Oral antivirals (virus in skin)

• Topical antibiotic ointment (prevent secondary infection)

Herpes zoster ophthalmicus epithelial keratitis Tx

Artificial tears

Herpes zoster ophthalmicus nummular/stromal/disciform Tx

Topical steroid

Herpes zoster ophthalmicus mucus plaques Tx

Topical steroid

Herpes zoster ophthalmicus neurotrophic keratitis Tx

• Artificial tears

• Bandage CL

• Amniotic membrane

• Cenegermin

Herpes zoster ophthalmicus post-herpetic neuralgia Tx

Early intervention with oral antivirals when rash develops to reduce risk