Download Everyday Extraocular Issues - Pennsylvania Veterinary Medical

Everyday Extraocular Issues
Rachel Allbaugh, DVM, MS, Diplomate American College of Veterinary Ophthalmologists
Iowa State University Department of Veterinary Clinical Sciences, Ames, IA
Entropion and Ectropion
Entropion is inward rolling of the eyelid margin while ectropion is eversion of the eyelid margin.
Both may occur due to tight medial and/or lateral canthal attachments and/or an overly long
eyelid and affect certain breeds of dogs more frequently than others. Entropion can result in
corneal irritation, vascularization, scarring and even ulceration while ectropion rarely causes
more pathology than simple irritant-induced conjunctivitis. Entropion in young animals should
be addressed with temporary nonabsorbable vertical mattress tacking sutures to evert the
eyelid margin (repeated q. 3-4 weeks as needed). Some patients will outgrow their entropion
while others may require permanent surgical correction when they are more skeletally mature
(e.g. 6 months or older). The most common entropion surgery is the Hotz-Celsus procedure
with or without eyelid wedge resection to shorten eyelid length and/or lateral canthal
tenotomy. Keys to Hotz-Celsus surgery include making the incisions long enough to extend
beyond the entropic area, incising within 2 mm of the eyelid margin (at the haired/nonhaired
border), removing sufficient subcutaneous tissue to allow natural skin closure while not taking
too much total tissue, and closing by the law of bisection. Though large breed dogs are best
treated with the above procedure small breed dogs with medial lower eyelid entropion (and
sometimes nasal trichiasis that results in tear wicking) could undergo small Hotz-Celsus or
medial canthoplasty surgery to address the issues. Ectropion that causes persistent
conjunctivitis can be managed conservatively with daily eye rinsing to remove microscopic
debris that settles in the resultant tear pool/conjunctival pocket or with surgery if corneal
pathology or cosmetic concerns occur (e.g. with eyelid wedge resection, V to Y blepharoplasty,
or more advanced procedures).
Macropalpebral Fissure
This occurs with overly large eyelid openings and is most common in brachycephalic dog breeds
with shallow orbits and resultant conformational exophthalmos. These dogs may be at a higher
risk of traumatic ocular proptosis also. Some of these patients may not be able to blink their
eyelids closed completely (lagophthalmos) and have chronic exposure of the central cornea.
Others may have concurrent conformational issues, such as medial lower lid entropion and
trichiasis, which further irritate and may result in damage of the cornea. Patients with evidence
of corneal pathology (e.g. pigmentation, vascularization, ulcers) benefit from surgical
shortening of the eyelids. A medial canthoplasty surgery is most appropriate to shorten the lids,
allow complete blinking, as well as address medial lower lid entropion and medial canthal or
nasal trichiasis. Careful eyelid margin apposition is necessary (magnification required) to
prevent iatrogenic entropion following canthus closure. An additional medial temporary
tarsorrhaphy suture helps to protect the surgical site during the postoperative healing stage.
Regardless of surgery, ocular lubrication BID-QID is beneficial to help minimize ocular exposure
and irritation while cyclosporine or tacrolimus ophthalmic medication BID may help to reduce
corneal pigmentation. These therapies should be started early in an effort to prevent vision
compromise which can occur in any patient with macropalpebral fissure and lagophthalmos.
Trichiasis
Trichiasis hairs are normally positioned cilia that are abnormally directed against the cornea. In
many dogs these hairs are fine and soft so even if they contact the ocular surface reflex tearing
allows them to float in the tear film. This is most commonly seen at the medial canthus.
Conditions where trichiasis may be problematic include nasal fold trichiasis with stiff hairs (e.g.
extremely brachycephalic pugs) or any form of trichiasis when combined with
keratoconjunctivitis sicca as both may result in corneal abrasion or ulceration. Dogs with nasal
trichiasis and conformationally blocked lower eyelid puncta (functional nasolacrimal duct
obstruction) manifest with epiphora as tears take the path of less resistance along the hairs and
over the eyelid. Treatment of trichiasis or associated conditions may be needed for patients
with corneal disease or owners frustrated by facial wetting.
Distichiasis
Distichiasis is a condition in which one or more hairs emerge from upper or lower eyelid
meibomian gland orifices along the eyelid margin. The hairs are abnormal in location and
variable in their clinical manifestations. Hairs are first noted in juvenile dogs, but follicles may
continue to mature into early adulthood. When fine, soft, or few in number distichia tend not
to cause clinical signs or require therapy. They may be found incidentally in certain overrepresented breeds such as Cocker Spaniels. Distichia hairs that are stiff, numerous, or when
they occur in dogs with even slight inward deviation of the eyelid margin are most likely to
cause concern. Patients may manifest with squinting, tearing, and rarely corneal ulceration.
Magnification greatly facilitates examination of the eyelid margin and identification of these
aberrant hairs. Manual plucking can be performed with jeweler’s or epilation forceps to remove
hairs and confirm if signs resolve until the hairs regrow. Cryoepilation is recommended for
permanent follicle treatment and hair removal.
Ectopic cilia
An abnormal hair that protrudes through the palpebral conjunctiva is termed an ectopic cilium.
They are typically found in young dogs with clinical signs of ocular pain, tearing, and corneal
ulceration due to the perpendicular orientation against the corneal surface. Magnification is
necessary to identify an ectopic cilium. A persistent or recurring corneal ulcer can suggest an
adjacent eyelid location warranting critical examination for an aberrant hair bristle. Pigmented
conjunctival foci may be present at or near the site of ectopic cilia, but not always. En bloc
surgical resection of ectopic cilia from the palpebral conjunctival surface is ideal and adjunctive
cryotherapy may be used to treat the tissue bed to further reduce the risk of recurrence.
Eyelid Masses
Eyelid masses are common in older dogs and most are benign. Tumors may include those
involving skin tissues (papilloma, melanoma, mast cell tumor) or more commonly glandular
tissue with meibomian gland adenomas being the most frequent canine eyelid neoplasm. Small
tumors may be monitored over time but if they abrade the cornea they can cause irritation and
even corneal ulceration. Eyelid wedge or house (4-sided) resection is a simple procedure that
removes full thickness eyelid tissue with keys to the surgery including not removing more than
30% of the eyelid length, making sure the margin to apex distance of the excision is twice the
width of margin removed, and ensuring accurate eyelid margin apposition. However, this
surgery is typically not needed for adenoma removal and these tumors are better managed by
debulking and cryotherapy or carbon dioxide laser excision through the palpebral conjunctival
surface. The latter therapies minimize eyelid margin and skin impact, prevent surgical eyelid
shortening and can also be used to address chalazion formation. For larger masses or
potentially malignant neoplasms referral for grafting procedures and adjunctive therapy may be
necessary.
Eyelid Lacerations
Eyelid wounds may occur from animal fights, car accidents or other trauma and though general
principles of skin wound treatment and healing still apply there are some important
considerations periocularly. Artificial tear ointment or lube should be applied to the eye prior to
clipping to prevent hairs from irritating the cornea. Dilute betadine and saline solution should
be used to gently clean the wound instead of chlorhexidine or alcohol as they are toxic to the
corneal epithelium. Wounds should not be debrided, or only very minimally with 4x4 gauze, as
eyelids have wonderful vascular supply and healing potential. Eyelid margin apposition is most
important to ensure proper function and can be achieved with a symmetrically placed figure of
eight suture or simple interrupted sutures with suture ends engaged in subsequent skin suture
knots to direct them away from the corneal surface. Soft, braided suture (e.g. Vicryl ®) is
optimal to further minimize the risk of corneal abrasion. Longer lacerations may require twolayer closure with buried sutures placed prior to eyelid margin apposition while being sure not
to penetrate the palpebral conjunctiva. Postoperative management includes topical ophthalmic
antibiotic +/- corticosteroid TID, oral antibiotic, a systemic anti-inflammatory +/- other pain
control and an Elizabethan collar to prevent self-trauma until suture removal in 10-14 days.
Third Eyelid Gland Prolapse
The third eyelid gland encompasses the base of the third eyelid cartilage and can prolapse to
become visible extending beyond the edge of the third eyelid margin due to weakened
connective tissue attachments. This occurs more commonly in certain dog breeds and typically
at a young age. Glands that remain out of place become inflamed, enlarged, and are unsightly.
Aqueous tear production can also be impacted which is of great consequence given its normal
lacrimal role and the fact that many affected breeds are also predisposed to KCS. Prolapsed
glands should be repositioned using any one of a variety of techniques based on the individual
surgeon’s preference and rate of personal success as no technique is 100% effective. The
Morgan pocket technique is utilized commonly and if suture knots are tied on the
anterior/palpebral surface of the third eyelid it reduces the risk of iatrogenic corneal trauma
from suture material. Bulldogs with third eyelid gland prolapse may be particularly difficult to
manage and may warrant referral to a specialist to maximize surgical success. Third eyelid
glands should never be removed for this condition.
Everted Third Eyelid Cartilage
Cartilage eversion is a problem that may affect one or both third eyelids of some young large
breed dogs. The third eyelid cartilage stem generally folds near the neck of the “T”, allowing the
leading edge of the third eyelid to inappropriately evert outward away from the cornea or, less
commonly, inward toward the cornea. This is easily differentiated from a prolapse of the third
eyelid lacrimal gland by the glistening cartilage convexity visible through the conjunctival
surface. Though folded cartilage does not typically cause corneal pathology or visual
compromise, the inappropriate third eyelid margin position impairs optimal tear film
distribution and drainage, may contribute to conjunctivitis and exposure keratopathy, and is
unsightly to most pet owners as the third eyelid no longer conforms to the ocular surface.
Patients are treated by surgical resection of the bent portion of cartilage, cartilage removal and
homotransplantation, or careful application of thermal cautery to remodel the cartilage and
return the third eyelid to a normal position. The medial and lateral tips of the cartilage may also
be affected and can be similarly treated with cautery being my personal treatment preference
for this condition.
Orbital Cellulitis and Abscess
Orbital inflammation (cellulitis) or abscess formation results in increased space occupation
within the orbit and causes anterior displacement of the globe (exophthalmos) and third eyelid
elevation. Common etiologies include penetrating injury through the roof of the mouth (e.g.
from chewing on a stick or bone), a tooth root abscess, and potential hematogenous spread of
an infectious agent. In addition to exophthalmos and an elevated third eyelid, globes will be
resistant to retropulsion and animals may demonstrate pain on orbital palpation or mouth
opening manifesting as anorexia and decreased water intake. Fever may or may not accompany
the condition. Oral examination may demonstrate a swelling or draining site behind the last
upper molar on the affected side, but not always. Orbital ultrasound can be used to look for
evidence of a foreign body as well as a fluid pocket suggestive of an abscess. If an abscess is
present, drainage can be performed via an oral approach while under general anesthesia with
samples collected for culture and cytology. Patients without a fluid pocket have orbital cellulitis
and should not undergo probing exploration given the risk for iatrogenic introduction of
additional bacteria from the mouth. In either case extended therapy with an appropriate
systemic antibiotic (e.g. Clavamox®) for 4-6 weeks is recommended as well as a systemic antiinflammatory. A corticosteroid injection (e.g. Dexamethasone 0.2 mg/kg IV) can quickly
alleviate discomfort and improve appetite in affected animals to facilitate subsequent oral
medication administration. Systemic corticosteroids can be continued at an anti-inflammatory
dose for 1 week then gradually tapered. If inflammation recurs when off medication an inciting
cause may remain or another condition may exist (e.g. neoplasia or immune-mediated disease).
If a patient cannot completely blink to protect the cornea while exophthalmic an ocular
lubricant should be used QID to prevent corneal ulceration, or if a corneal ulcer is already
present an ophthalmic antibiotic ointment (e.g. Neomycin/PolymyxinB/Bacitracin) should be
used QID to help prevent ulcer infection and provide ocular lubrication. Canned food may be
needed for anorexic dogs for the first few days but the prognosis is generally very good for
orbital cellulitis and abscessation.
Ocular Proptosis
Proptosis occurs when the eyeball moves forward so far that the eyelids become locked behind
the equator of the globe. This occurs due to trauma, but may only require minor force in
brachycephalic breeds with shallow orbits and large eyelid openings. The prognosis will vary
with the severity of trauma (e.g. very poor prognosis in cats, horses, and dolichocephalic dogs
that require extreme force to result in proptosis) and status of the globe on presentation.
Salvage of the eye is much more likely than saving vision; however, many owners will still value
a blind eye that is cosmetic. If numerous extraocular muscles are torn (3 or more), the optic
nerve is transected, or the globe is ruptured it should simply be removed. Otherwise,
replacement should be attempted as soon as the patient is systemically stable.
Following proptosis the globe should be lubricated as frequently as possible to prevent
desiccation and corneal ulceration until the globe is surgically replaced. The eyelids can be
carefully clipped and prepared with eyewash and dilute betadine solution (1:50 dilution; do
NOT use betadine scrub, chlorhexidine, and/or alcohol as they are toxic to the corneal
epithelium). A lateral canthotomy may be needed to relieve eyelid tension prior to globe
replacement and should be performed with scissors instead of a blade to avoid globe damage.
Once the globe is back in the orbit the eyelids are sutured closed with horizontal mattress
sutures as a temporary tarsorrhaphy ensuring appropriate suture passage to prevent corneal
irritation. The medial eyelids should be left open so ophthalmic medications can be applied at
the medial canthus.
Post-replacement an e-collar should be placed to prevent self-trauma and medications
prescribed to prevent infection (topical +/- systemic antibiotic), reduce inflammation (systemic
anti-inflammatory), and relieve pain (topical atropine, systemic tramadol or other narcotic).
Recheck can be performed within one week to assess suture position and ensure none are
rubbing on the cornea as eyelid swelling decreases, though it is optimal to leave tarsorrhaphy
sutures in place for up to 3 weeks. Following suture removal a complete ophthalmic exam
should be performed, including STT, fluorescein staining, and assessment of complete eyelid
closure. Possible complications post-proptosis are KCS due to lacrimal gland inflammation or
duct damage, lagophthalmos and exposure keratitis due to eyelid stretching, and lateral
strabismus due to medial rectus muscle damage. Some of these complications may resolve with
time but in the interim globes will require supplemental ocular lubrication BID-QID (e.g.
GenTeal gel or Optixcare).
Recommended Veterinary Ophthalmology Textbooks:
*Slatter’s Fundamentals of Veterinary Ophthalmology, 5th edition. David J Maggs, Paul E Miller
and Ron Ofri. Saunders Elsevier. 2012 ($115 or less)
*best recommendation for a general ophthalmology resource
Essentials of Veterinary Ophthalmology, 2nd edition. Kirk N Gelatt. Blackwell Publishing. 2008
Veterinary Ophthalmic Surgery. Kirk N Gelatt and Janie P Gelatt. Saunders Elsevier. 2011
Ophthalmic Disease in Veterinary Medicine. Charles L Martin. Manson Publishing Ltd. 2010