Ch 124 Basic eye surgery

Question 1

Anatomy eyelids

Answer 1

• All eyelid muscles are innervated by the branches of the facial nerve, except for the levator palpebrae superioris (oculomotor nerve)
• Sensation to the eyelids and corneal surface is provided by branches of the trigeminal nerve,

Question 2

suture

Answer 2

• polyglactin can be and is routinely used for skin apposition around the eyelids.
• excellent knot security and handling, along with the fact that it becomes soft when wet, make it a good choice
• absorbable, polyglactin sutures do not need to be removed

Question 3

Eyelid Neoplasia

Answer 3

• meibomian gland tumors, squamous papillomas, melanomas, and histiocytomas make up more than 80% of all eyelid tumors
• removal we recon
• enucleation of the globe may be necessary

Eyelid reconstruction techniques
- Two-layer closure used to appose margin: Mattress suture to appose tarsus and orbicularis muscle layer + Figure of eight suture for skin
- Sliding Pedicle Advancement Flap (Defects that involve more than one-third of the eyelid margin)
- Myocutaneous Pedicle Graft (reconstruction of defects of the upper eyelid that involve large portions of the eyelid margin)
- Semicircular Flap
- Lip-to-Lid Flap

Question 4

Nictitating Membrane Gland

Answer 4

prolapse (Cherry eye)
- Orbital Rim Anchoring Technique
- Morgan Pocket Technique

Excision of the Nictitating Membrane
- Hemangiomas are the most common in dogs and squamous cell carcinomas in cats.

Question 5

orbit anatomy

Answer 5

• medial, dorsomedial, and lateral walls of the orbit are bone
• muscles of mastication and soft tissues of the soft palate make up the dorsolateral and ventral orbital boundaries
• sphenoid bone, which forms the caudomedial boundary of the orbit.
• Distinct compartments within the orbit are formed by reflections of the fibrous periorbita (also called the orbital septum)

Question 6

Space-occupying lesions reported to cause exophthalmos

Answer 6

• tumors,
• zygomatic mucoceles
• arteriovenous malformations
• extraocular and masticatory muscle myositis
• hemorrhage
• orbital cellulitis or abscessation

Definitive diagnosis, determination of the full extent of involvement, and surgical planning usually require CT or MRI and fine needle aspiration or biopsy.

Question 7

retrobulbar abscess

Answer 7

• transoral orbitotomy to provide drainage and obtain bacterial culture and sensitivity
• surgical treatment is rarely indicated because most orbital abscesses respond to medical therapy

Question 8

Exenteration

Answer 8

• removal of all the orbital contents
• Care must be taken not to remove the muscular floor of the orbit or lacerate the maxillary artery that runs through it.

Question 9

Orbitotomy

Answer 9

Modified Lateral Orbitotomy
- used for all extraconal lesions, except for those medial to the muscle cone, and all intraconal lesions.
- orbital ligament is transected
- facial vein and venous plexus that are closely associated with the rostral extent of the zygomatic arch
- osteotomy

Orbitectomy
- When neoplasia affects the bones of the orbit, chemotherapy or radiation therapy alone may not provide satisfactory control

Question 10

Globe removal - enucleation

Answer 10

Subconjunctival Approach:
- incision through the conjunctiva and Tenon’s capsule
- Care must be taken to avoid lacerating the angularis oculi vein, which runs over the surface of the medial orbital rim
- Care must be taken to not place too much traction on the globe when transecting the optic nerve
- remove all of the conjunctival tissue
- third eyelid is excised

Transpalpebral Approach
- An incision through the skin, completely surrounding the palpebral fissure
- xtraocular muscles are visualized, they should be transected at their tendinous attachment to the globe
-

Question 11

Strontium 90 plesiotherapy for the
treatment of eyelid squamous cell
carcinoma in eight cats
Onne-Marju Russak 2022

Answer 11

In six
cases, ST-90 was used as the only treatment modality, while in two cats it was used as an adjuvant to surgery. Four
cats received a single protocol and four a hypofractionated protocol. In the six cats in which ST-90 was used as the
primary treatment, the response was 100%.

no signs of recurrence at a median time of
34 months

early stage (such as carcinoma in situ Tis or T1),

SE: alopecia

Question 12

Tumours involving the retrobulbar
space in cats: 37 cases
Bryn A Jones 2022

Answer 12

Thirty-two cases (86%) had secondary extension
of neoplasia to the retrobulbar space (most commonly from the nasal cavities), (54%), of which
12 were lymphoma.
36 (97%) retrobulbar tumours were malignant. Thoracic imaging,
where it was performed, was concerning for metastasis in 8/25 cases (31%), with abdominal imaging suggestive of
metastasis in 5/12 (42%).

The most common diagnosis was lymphoma with 19 cases (51%), carcinoma in 10 (27%). The median survival time, for cases where death was
recorded, was 85 days (range 1–263 days).

Question 13

Patterns of bacterial culture and antimicrobial
susceptibility test results for dogs
with retrobulbar abscesses: 133 cases (2002–2019)
Stephanie A. Pumphrey 2020

Answer 13

multiple isolates recovered from 54 (56%) of those dogs.
34 (49%) had purely aerobic infections,
15 (22%) had mixed aerobic and anaerobic infections,
20 (29%) had purely anaerobic infections. Pasteurella, streptococcus spp (20), and Escherichia coli (12) were the most common aerobic Bacteroides , Actinomyces, and Fusobacterium (10) most common anaerobic

Susceptibility test results led to changes in (46%) dogs. 78 (97%) recovered

amoxicillin-clavulanate or a combination of clindamycin and enrofloxacin as first-line treatments

Question 14

X/Y shaped periorbital reconstructive
surgery following enucleation or
exenteration in dogs and cats: 24 cases
(2013-2020)
Vlachomitrou 2021

cinti

Answer 14

Nineteen dogs and five cats were included in the study
two cats and two dogs showed eyelid depression (16%)

incisions parallel to the orbital rim of the frontal bone were made into the collagenous
connective tissue and periosteum

Question 15

Transorbital postcaruncular endoscopic surgery
as an alternative to orbital exploratory surgery: A cadaveric
study and case report in a dog with an orbital sarcoma
Filipe N. C. M. Espinheira Gomes

Answer 15

Transorbital endoscopy was performed to obtain biopsies of an
orbital apex mass by using a postcaruncular approach. A 2.7-mm 30  rigid
endoscope fitted with a cystoscope working sheath was used with the aid of a
blunt suction-dissector and fluid ingress

This technique should be considered in cases in which a
histological diagnosis is required prior to definitive treatment as a method to
obtain biopsy samples of the orbital apex region without major surgical dissection.

Question 16

Use of a temporalis fascia transposition flap for ventral orbital
stabilization after ventral orbitectomy in a dog
Brian Dent 2019

Answer 16

No complications occurred during the procedure
Clinical significance: A temporalis fascia transposition flap can be used to reconstruct
the ventral aspect of the orbit in dogs.

alternative
- masseter muscle flap
- cerclage wire,
- polypropylene mesh,
- orthopedic steel plate

Question 17

Outcome of secondary intention healing of full thickness lower eyelid defects in dogs
M. W. Jack 2019

krosse

Answer 17

three dogs
70 to 90% of the lower eyelid margin
not all lower eyelid resections require anatomical reconstruction. Selected cases can be left to heal by secondary intention with minimal post-operative complications
anatomical reconstruction is traditionally recommended because corneal health is thought to rely on normal eyelid position and integrity
> dogs were able to move their third eyelid laterally when blinking. This can occur due to abducens nerve stimulation