Chapter 124 Basic Ophthalmic Surgical Procedures Flashcards
What alternatives (equally effective) are there to retrobulbar bock?
- Absorbable gelatin haemostatic sponge infused with lidocaine-bupivacaine
- Intra-op bupi splash block
What is the oculocardiac reflex
How is it treated?
Traction/pressure on globe –> bradycardia
Tx: glyco or atropine (0.02 mg/kg iv) (glyco potentially preferable as not associated tachycardia or dysrythmia)
How is eye area prepped for surgery
- Clip with eye lube
- Trim cilia with scissors
- 1:50 diluted (0.2% solution) povodine:iodine prep alternating with sterile saline
Name 4 ophtho specific GA things
- Armoured ET tube
- Neuromuscular blockage
- Be prepared for oculocardiac reflex
- Avoid drugs –> rise in IOP
Name 3 post-op ophto consideratins
- BC!
- Smooth calm recovery
- Atropine (cycloplegic) for cornel procedures
What material is used for haemostatsis in ocular surgery and why.
How else can haemostasis be achieved?
Wedge shaped cellulose sponges as do not shed fibres
Topical ophthalmic phenyleprine or 1:10,000 epinephrine
Name the instruments
- Barraquer eyelid speculum
- Jaeger eyelid plate
- fine toothed Bishop-Harmon forceps
- Derf needle holders
- Steven’s tenotomy scissors
Name 4 methods to improve globe exposure
- Barraquer or Castroviejo eyelid speculum
- Scleral fixation sutures
- Lateral canthotomy (terminate before lateral canthal ligament)
- Neuromuscular blockade
Label the diagram
Another name for meibomian gland
Tarsal gland
Who knew!!
Label the diagram (include innervation)
List the four muscles that elevate upper lid
- Levator palpebrae superioris + Müllers muscle
- Levator anguli oculi medialis
- Frontalis
List the muscle(s) that lower lower lid
- Malaris muscle
What nerve provides sensory innervation to eyelids and corneal surface
Trigeminal nerve
(corneal = ophthalmic branch)
All but 2 muscles of the eyelids are innervated by the facial nerve. What are the two exceptions?
- Levator palpebrae superioris innervated by Oculomotor n (CN III)
- Müller’s muscle (sympathetic innervation)
What is origin and insertion of orbicularis oculi?
Medial ligament
What does ankyloblepharon mean?
What is sequence of tx?
What method should be avoided?
What additional test should be performed?
"”Ankylosis” of eyelids i.e. puppies eyelids not opened by normal time post-partum (>14d). Usually secondary to infection
Tx:
- Hot compress
- Hot compress + manual separation
- Mosquito forcep through medial fissure + separate
Do not sharply incise as leads to eyelid margin damage
Check for ulcers
What is most common location of eyelid agenesis in cats?
And in dogs?
When is tx recommended
Cats: Upper lateral
Dogs: Lower central or lateral
Tx if causes keratitis
What conditions have been associated with eyelid agenesis (6)
- Lacrimal gland agenesis
- KCS
- Persistent pupillary membrane
- Cataract
- Retinal dysplasia
- Optic nerve coloboma in cats
How is entropion classified?
- Conformational
- Cicatricial
- Involutional
- Spastic
How is entropion accurately assessed pre-op.
Why?
MUST asses:
- Consious
- Unsedated
- After topical anaesthetic
- All other potential causes addressed (ie do fluoroscein, STT, ectopic cilia/distichiasis, IOP, aqueous flare?)
All entropion have a spastic component (orbicularis oris spasm due to painful stimulus) - if asssessed before this component is eliminated will lead to excessive tissue excision
HOw does entropion surgery differ in cats?
Should slightly over-correct
List 3 techniques for management of entropion
- Temporary correction (vertical mattress sutures)
- Hotz-Celsus procedure (can do two mini crescents at the sides instead of ne big one, depending on location of entropion.
- Stades procedure
What condition is treated with the Stades procedure.
Briefly describe procedure and why this technique is used
Stades procedure (aka forced granulation entropion repair) to treat upper lid entropion in breeds with heavy brows + long hair on upper eyelid
(A). A hemicircle of skin is resected
(B) and the dorsal edge of the wound is sutured to the subcutis
(C-D). The remaining wound heals by second intention (meaning that hair doesnt grow there)
List the two broad aetiologies for ectropion and how each is managed?
- Overlong palpebral fissue
- Wedge resection (undercorrect by 0.5-1mm to allow for fibrosis)
- Modified Kuhnt-Szymanowski procedure (= margin sparing - see image)
- Contraction of scar tissue (laceration, previous entropion surgery)
- V-Y plasty
What is euryblepharon?
How is it treated?
Euryblepharon = symmetric enlargement of palpebral aperture secondary to longer than normal eyelids (think brachy + CKCS)
Tx: Medial canthoplasty (ideally by pocket technique) + temoprary tarrshorraphy to support repair
What are distichia?
Name two treatment options.
Cilia exiting meibonion glands
Tx:
- Cryoepilation
- Electroepliation
Cryoepilation is best performed by fast freeze-slow thaw (two cycles total). How is this achieved?
How do you know an approprite amount of cryoepilation
Name 2 possible post-op changes
Chalazion clamp applied to area being treated
Stop when ice ball reacjed eyelid margin.
May see decreased lipid portion of tear film (tx with petroleum based lube) + depigmentation for up to 6 months is normal
What are ectopic cilia and how are they treated
Hairs abberrantly protruding through conjunctiva.
Tx = excision of hair and meibomian gland
What is the most common canine eyelid tumour?
List 3 other common neoplastic ddx
What is most common feline eyelid tumour?
Meibomian gland adenoma most common in dogs
Other ddx:
- Squamous papilloma
- melanoma
- Histiocytoma
SCC most common in cats
What is teh name of the lesion arising from blocked meibomian gland?
Chelazion
(remember - chelazion clamp)
Name a pre-op treatment recommendation prior to eyelid tumour removal and justify
Pre-treat with topical steroids to relieve potential obstruction caused by tumour –> reduced meibominal gland drainage i.e. chalazion (most meibomian gland tumours have a degree of chalazion when assessed histologically)
What two resection techniques can be performed for eyelid mass
- Wedge resection
- Pentagonal resection (make height of pentagonal excision x2 width for cosmetic reconstruction)
What size of eyelid defect can be closed primarily?
1/3rd eyelid length
Name 6 techniques to close an eyelid defect
- Simple two layer closure (can be single layer if small)
- Sliding pedicle advancement flap
- Myocutaneous pedical graft
- Semicircular flap
- Lip-to lid flap
- Temporal horizontal H figure sliding flap (for central eyelid reconstruction - Giordano, JSAP, 2017)
Breifly describe technique for myocutaneous pedicle flap for reconstruction of an eyelid defect
Myocutaneous pedicle graft as described by Dziezyc and Millichamp for the repair of eyelid agenesis.
- The abnormal eyelid is reconstructed with a laterally based flap from the unaffected lid (A-C).
- The conjunctiva can be harvested from the anterior surface of the third eyelid as depicted (D-F), or the graft can be lined with mucosa from a different site, buccal mucosa, or not lined at all.
At what angle (relative to line between medialand lateral canthus) are inscisions for lip-to-lid flap made?
At what layer shodl it be undermined?
45-50º
Undermine beneathy platysma m.
What procedure has been performed
Semicircular flap
Where along eyelid margin should temporary tarrsorrhaphy sutures exit?
Level of meibomian gland openings
What are the three components of tear film (from inner to outer layer) and where does each come from
- Innermost - mucin - goblet cells in conjunctiva
- Middle - aqueous- lacrimal glands in dorsolateral orbin and nictitans membrane
- Outer - lipid (prevent evaporaton of aqueous) - meibomian glands near eyelid margins
Describe the anatomy of the nasolacrimal drainage syste
Dorsal and ventral cannaliculi at medil canthus –> lacrimal sac –> lacrimal duct –> lacrimal canal of lacrimal bone and maxilla –> opens vetrolateral floor of nasal vestibule
What is NL duct patency checked?
Fluoroscein dye passage at nostril/in mouth afetr 3-5 minutes (Jones 1 test)
List 6 ddx for NL duct blockage
- Punctal aplasia
- Nasolacrimal cysts
- dental disease
- Neoplasia
- FB
- dacryocystitis
What does STT assess?
What is considered KCS?
TX?
Aqueous portion of tear film
<10 = KCS (<15 borderline)
Tx:
- Topical immunosuppressant: cyclosporine or tacrolimus
- Initally topical abx and lube
- PDT (open or closed techniques) if medical management fails
Label the diagram (i.e. structures to take care of in PDT surgery)
Cutaway drawing of the surgical field used for a parotid duct transposition. The facial muscles have been omitted so that the essential features can be seen.
1, Dorsal buccal nerve;
2, anastomosis of dorsal buccal and ventral buccal nerves;
3, ventral buccal nerve;
4, parotid salivary gland;
5, parotid duct;
6, papilla of parotid duct;
7, facial vein;
8, upper carnassial tooth.
What should be performed prior to PDT
Ensure salivary flow from parotid duct!
- Apply a drop of bittersubstance (e.g. atropine) on tongue
Where does parotid duct open?
Where does zygomatic papilla open
Parotid: Caudolateral to carnassial
Zygomatic: Gingival border of last molar
Label the diagram (i.e. proper names for different parts of conjuntiva)
Specific areas of the conjunctiva.
1, Palpebral conjunctiva;
2, conjunctival fornix;
3, palpebral side of the nictitating membrane;
4, bulbar side of the nictitating membrane;
5, bulbar conjunctiva.
What are the two surgical planes of the conjunctiva?
- Between conjunctival epithelium and Tenon’s capsule (subjacent to the epithelium is the substantia propria (Tenon’s capsule), where lymphoid follicles reside). Used for conjunctival grafts
- Between Tenon’s capsule and sclera
List 5 ddx for non-neoplastic conjunctival mass
- Dermoid
- Subconjunctival prolapse of orbital fat
- Onchocerciasis
- FB
- Granulomatous diseases
- Staphyloma
What is symblepharon and what condition is it associated with?
Symblepharon is abnormal attachment of the conjunctiva to itself, the cornea, or the nictitating membrane
Usually secondary to herpesvirus
How is movement of the nictitating membrane achieved in dogs?
And in cats?
Passive in dogs (globe retraction)
Cat has smooth muscle bands extending into nictitating membrane
What % of tear film is produced by nictitating membrane?
35%
What breed is predisposed to everted nictitating membrane i.e. scrolled cartiladge)
German Shorthaired Pointers
What is the most common primary disrder fo the nictitating membrane?
Prolapse of nictitating membrane gland i.e. cherry eye
List two techniques for management of prolapse of the nictitating membrane gland
- Orbital rim anchoring technique
- Morgan pocket technique
- (+ Tacking to base of nictitating membrane cartilage)
- (+ Anchoring with a suture around insertion of ventral rectus muscle)
Describe a key step in the MOrgan pocket technique for management of prolapsed nictitating membrane, and why the step is important
Leave 2-3mm of mucosa intact at either end of pocket to allow continued tear drainage
What is most common tumor of nictitating membrane in dogs?
And in cats?
Haemangioma in dogs
SCC in cats
Label the diagram (histo of cornea)
Normal cornea.
A, Epithelium.
B, Stroma.
C, Descemet’s membrane.
D, Endothelium
What is the approximate thickness of cornea in dogs and cats?
0.5mm
What type of epithelium does the cornea have?
How thick is it?
Non-keratinised, stratified squamous epithelium
Approx 6 cells thick
List 6 features of the cornea that make transparency possible
- Non-keratinized epithelium
- Lack of vessels
- Lack of pigment
- Perfect alignment of stromal lamella with few stromal cells
- Smooth optical surface
- Relative dehydration
What nerves supply the corneal
Where in the cornea are they located?
Long ciliary nerves (branches of ophthalmic brach of trigeminal nerve)
Located in epithelium and anterior stroma (hence superficial ulcers more painful.
What type of ulcers do Boxer’s usually get?
How are they recognized?
SCCED (spontaneous chronic corneal epithelial defect)
Usually jagged edges of epithelium at ulcer + fluoroscein leaks under epithelium
How are SCCEDs treated
How does this differ in cats and why?
Tx:
- Debride loose epithelium
- Keratotomy (grid, punctate or diamond burr)
- (+- contact lens)
- Topical abx + atropine
Dont do keratotoym in cats as more likely to get sequestrum
What antibiotic shoud be used in treatment of scceds and why?
Oxytet ophthalmic ointment (tid) as results in more rapid healing than triple abx ointment (tid)
What shoudl owners of scced be warned about pre-op
May need repeat sx.
How can refractory scced cases be treated
Cyanoacrylate or superficial keratectomy
What condition is shown?
Name 5 other signs that can be seen with this condition
Corneal sequestrum in a cat
- Epiphora
- Blepharospasm
- Corneal vascularisation
- Perilesional corneal oedema
- Ulceration
Note the circular black axial sequestrum, corneal vascularization, and associated perilesional corneal opacification.
How is corneal sequestrum managed?
- Treat any concurrent herpes virus first
- Keratectomy
- Then place conjunctival graft, or corneal conjuntival transposition or lamellar keratoplasty to avoid further ulcer which could trigger another sequestrum
Which breed is predisposed to sequestrum
Brachycephalic breeds
List 4 types of corneal neoplasia that have been reported
- Limbal melanoma (usually benign…)
- SCC
- Vascular tumours
- Viral papilloma
What are the 2 primary ddx for limbal melanoma
Uveal melanoma that has penetrated cornea and sclera
Staphyloma
How many keratectomies can be performed without risk of thinned weakened cornea.
What shoudl be done if keratectomy extends beyond half of stroma?
2-3
Support with pedicle flap
Through what bone do all nnerves and vessels supplyign eye course?
Sphenoid bone
Where is zygomatic gland located in relation to orbit
Ventrolateral (i.e. ventromedial is LN)
What do the terms extraconal and intraconal refer to?
Periorbita surrounding the muscular cone is continuous with the dura of the optic nerve caudally and with Tenon’s capsule rostrally.
Lesions that are within the periorbita surrounding the extraocular muscle cone are termed intraconal, and those outside are termed extraconal.
The orbital fat body fills the interstices of the orbit and serves to cushion the eye and the orbital contents and maintain the eye within the plane of the orbital rim.
Label the diagram
List ddx for exopthalmos
- Neoplasia
- Haematoma
- Cyst
- Granuloma
- Abcess/cellulistis
- Zygomatic mucocoele
- AV malformation
- Masticatory or extraocular myositis
What structure has to be protected during exenteration
Maxillary artery
What approach offers greatest exposure to intra-orbital structures?
What structures cant be accessed with this approach
Modified lateral orbitotomy
Cant access structures medial to muscle cone
Breifly describe modified lateral orbitotomy
What structure should be preserved?
How can exposure be increased?
Modified lateral orbitotomy (care re palpebral nerve, just dorsal to inscision)
- Holes are drilled on each side of the planned osteotomy with 0.035-inch K-wire.
- Retracting the zygomatic arch ventrally and the lateral canthus rostrally exposes the globe, the optic nerve, and extraocular muscles. (care re facial vein and venous plexus rostrally)
- The zygomatic arch is replaced using four 22 gauge wires. The orbital ligament is sutured with horizontal mattress sutures of 4-0 polyglactin.
Osteotomy of vertical ramus of mandible (up to midpoint is fine) for improved exposure to caudal and ventral orbit
Name 2 approaches for enucleation
What should be inspected after enucleation
- Transconjunctival
- Transpalpebral
Check for NL duct opening and ligate if visibile (reduced ascending infection risk theoretically)
What is the strenght holding layer during enucleation closure?
Orbital fascia
What procedure can be considered as an alternative to enucleation in a painful, non-visual, infectionand neoplasia free globe if o is concenred re cosmesis of enucleation
Evisceration
Ensure entire uveal tract, lens and vitreous are removed.
Name innervation to eye muscles
