Ocular emergencies (Proceedings)

Proptosis of the globe

      o Brachycephalic breeds are most likely due to conformation (shallow orbits and macroblepharon)

      o Excessive Restraint (neck pressure)

      o Traumatic incidence: Dog bite (most common), Hit by car

      o Visual Prognosis- guarded in most cases

      o Poor prognostic indicators

          ■ Avulsion of 3 or more extraocular m.

          ■ Absent consensual PLR

          ■ Presence of facial fractures

      o Objectives of Therapy

          ■ Replace globe quickly- usually surgical

               • Lateral canthotomy if needed

               • Gentle traction to pull lids over globe

               • Temporary Tarsorrhapies with stents

          ■ Prevention and treatment of uveitis, neuritis, corneal ulcers

               • Topical antibiotics, oral anti-inflammatory, oral antibiotics and pain meds

               • Elizabethan collar

               • Weekly rechecks to evaluate sutures

               • Suture removal 3 weeks or staged

      o Complications

          ■ Lateral Strabismus (medial and ventral rectus m. rupture)

          ■ Lagophthalmos and exophthalmos

          ■ Exposure keratitis

          ■ Decreased corneal sensitivity

          ■ Corneal degeneration, ulceration

          ■ Keratoconjunctivitis Sicca

          ■ Uveitis, glaucoma, cataract

          ■ Retinal detachment, retinal degeneration

          ■ Optic nerve degeneration, avulsion

          ■ Phthisis bulbi

Penetrating Corneal Lacerations

      o Lacerations that are leaking are best treated surgically ASAP

      o Degree of intraocular damage and integrity of cornea will determine type of surgical treatment

      o If surgery must be delayed due to other injuries, long traveling distance, etc. treat medically

          ■ Topical antibiotic solution (NO ointments)

          ■ Topical mydriatic solution if miotic

          ■ Systemic steroid to treat intraocular inflammation

          ■ Systemic antibiotics to prevent intraocular infection

          ■ E-collar, pain management

      o Surgical treatment of uncomplicated corneal lacerations

          ■ Direct suture

          ■ Conjunctival flap

          ■ Corneal transplant with or without flap

      o Post-op treatment

          ■ Same as above

Corneal lacerations with associated lens capsule tear

      o Surgical repair of laceration by direct suture or graft

      o Phacoemulsification of cataract or lens material through lens capsule tear or through capsulorhexis

      o Place Intraocular lens if possible

      o Post-op treatment same as above, topical steroids

Complications of corneal lacerations

      o Anterior/posterior synechia

      o Chronic uveitis

      o Phthisis bulbi

      o Secondary glaucoma

      o Cataract

      o Altered vision to vision loss

Descemetocele/perforation

      o Descemetocele= ulcer to the depth of endothelial basement membrane

      o Peripheral Fluorescein uptake with clear center

      o Perforation= fibrin plug, blood, iris adhered to cornea, collapsed anterior chamber, aqueous humor leakage

      o Prompt, careful, thorough exam

          ■ Avoid excessive restraint so as not to rupture eye

          ■ Look for underlying cause (Dry eye, Distichiasis, trichiasis, ectopic cilia, entropion, Foreign body, Mineral degeneration, Facial n. or trigeminal n. dz)

          ■ Examine non-painful eye first, may give clues to inciting cause of painful eye (i.e. Dry eye, extra hairs, etc)

      o Prognostic clues

          ■ Presence of direct or consensual PLR

          ■ Clear view into eye

          ■ Size of ulcer

          ■ Integrity of cornea

          ■ Presence of other ocular disease

          ■ cataracts, retinal disease, glaucoma

      o Surgical repair

          ■ Direct suture if lesion <1mm

          ■ Conjunctival or corneal graft

          ■ Corneoconjunctival transposition flap

      o Post-op medications

          ■ Topical and systemic same as for laceration

          ■ Restricted activity and e-collar

Melting corneal ulcer

      o Corneal perforation within 12-24 hours if not treated aggressively

      o Causes usually bacterial (Pseudomonas aeroginosa, among many others)

      o Melting due to collagenase either from organism or WBCs

      o Look for underlying causes (Dry eye, lid abnormalities, hairs, ear/ skin infection, etc.)

      o Cytology and Culture and sensitivity

      o Tonometry- reflexive uveitis often causes ocular hypertension

      o Treatment and follow up

          ■ Topical antibiotics every 1-2 hr

          ■ Topical anti-collagenase every 1-2 hr (Serum, EDTA, Mucomyst)

          ■ Topical mydriatics to improve reflexive uveitis and prevent synechia

          ■ Systemic antibiotic and steroids

          ■ Follow up within 12-48 hours

          ■ Surgical if perforation is imminent

Acute Primary Glaucoma

      o Clinical Signs of Glaucoma

          ■ Palpably hard eye

          ■ IOP greater than 30mmHg

          ■ Pain and lethargy

          ■ Corneal edema

          ■ Enlarged globe if chronic

          ■ Dilated, unresponsive pupil

          ■ Episcleral vascular congestion

          ■ Vision loss (not always)

          ■ Intraocular pressure >25mmHg

      o IOP spike can permanently damage optic nerve within hours

      o Predisposed breeds

      o Examination and diagnostics

          ■ Menace response? Dazzle reflex?

          ■ Pupil size

          ■ Direct PLR?

          ■ Indirect PLR?

          ■ Direct/indirect ophthalmoscopy

          ■ Gonioscopy (contralateral eye)

          ■ Tonometry

          ■ Prompt treatment

      o Initial medical treatment

          ■ V mannitol or oral glycerin

          ■ Oral carbonic anhydrase inhibitors (Methazolamide)

          ■ Topical beta-blocker (Timolol 0.25% OR 0.5%)

          ■ Topical carbonic anhydrase inhibitor (Dorzolamide 2%)

          ■ Topical prostaglandin F2-alpha analogue (Xalatan)

          ■ Topical +/- oral anti-inflammatory

      o Surgical treatment for glaucoma

          ■ Diode laser cyclophotocoagulation (transcleral or endo laser)

          ■ Cyclocryothermy

          ■ Gonioimplant

          ■ Intrascleral prosthesis *

          ■ Enucleation *

          ■ Ciliary body ablation *

               • *for the permanently blind, painful eye

      o Primary glaucoma is a BILATERAL disease

          ■ Blind painful eyes with no chance of vision return best treated surgically

          ■ Prophylactic medical treatment of contralateral eye is beneficial

Lens Luxation

      o Partial or complete breakdown of zonules

      o Spontaneous- breed disposition: TERRIERS, Chihuahua, Spaniels, Shar Pei, Chinese Crested

      o Trauma can spur it on in predisposed breeds

      o Affects both eyes

      o Secondary lens luxation

          ■ Primary Glaucoma

          ■ Chronic uveitis

          ■ Intraocular tumors

          ■ Hypermature cataracts

      o History and presenting signs

          ■ blepharospasms, painful eye

          ■ red eye

          ■ corneal edema

          ■ Usually associated glaucoma- due to pupillary block with anterior lux

      o Lens position

          ■ Subluxation

          ■ Posterior luxation

          ■ Anterior luxation

               • Lens forcing iris forward

               • Lens partially through pupil

               • Lens completely forward and iris posterior to lens

      o Examination, diagnostics

          ■ Menace response? Dazzle reflex?

          ■ PLR: direct, indirect?

          ■ If can't see through cornea turn lights off and examine with focal light source or slit aperture

          ■ Applanation or rebound tonometry best

          ■ Shiotz tonometry can get falsely elevated IOP due to lens touching cornea

      o Treatment of Lens Luxation

          ■ Treatment of associated glaucoma with Mannitol IV

          ■ Miotics CONTRAINDICATED for high pressure such as Xalatan or Pilocarpine

          ■ Topical steroids if no ulcer

          ■ Systemic anti-inflammatory

          ■ Lens removal

References:

1. Essentials of Veterinary Ophthalmology by KN Gelatt; Fundamentals of Veterinary Ophthalmology by Slatter; Small Animal Ophthalmic surgery by KN Gelatt