Ocular dz/sx ch 10 Flashcards
Normal Schirmer tear test rx in ruminants
>15mm/min
Block for upper eyelid akinesia
Auricolupalpaebral nerve block (CN VII)
Can be done at varying sites caudolateral to lateral canthus or over zygomatic arch
In adults - local injected along the zygomatic arch caudolateral to the lateral eyelid commissure will → excellent upper eyelid akinesia in 5 min
Technique for Peterson block
What structures are desensitised?
12cm curved needle inserted in the angle between the frontal and temporal processes of the zygomatic bone, advanced and “walked off” of the cranial aspect of the coronoid process of the mandible, and then directed an additional 1 cm caudoventrally toward the foramen orbitorotundum - Mild proptosis should be present when the block is completed; should be complete anaesthesia of the contents of the periorbital connective tissue within 15-20 mins
ie behind the bony orbit, above the zygomatic arch & in front of coronoid process of mandible
Desensitises eyelids, orbit and globe
What is esotropia?
Bilateral convergent strabismus
Occurs +/-
Most common orbital neoplasm in cattle?
What is the main differential for exopthalmus other than neoplasia?
An adult dairy cow with nonpainful unilateral or bilateral exophthalmos of subacute to chronic onset most likely has lymphosarcoma
Ddx incl orbital cellulitis
How can PO lacrimocoele be prevented following transpalpaebral enucleation?
Rare in ruminants. All secretory tissue must be removed incl eyelid margins, lacrimal caruncle, conjunctiva, & gland of the third eyelid. Removal of the lacrimal gland itself not actually necessary as ducts severed
Recommended suture pattern for entropian of lower lid
Modified horizontal mattress suture:
Bite 1: through skin over the ventral orbit rim, needle directed toward the eye.
Bite 2: 2 mm away from the eyelid margin, split-thickness in the lid (never penetrating full thickness of the eyelid!), & parallel to the eyelid margin.
Bite 3) Directed away from the eye to exit 5-6 mm from the first bite.
As the suture is tightened, the lid margin should be guided outward, away from the cornea, before the suture is knotted
1-2 sutures usually sufficient
What is lagopthalmus?
List 2 treatment options
Inability to close the eye - usually dt CNVII damage, exopthalmus etc
Temporary tarsorrhaphy
Reversible split lid tarsorrhaphy
Describe procedure for reversible split lid tarsorrhaphy
15 blade or a #64 Beaver blade used to split the eyelids in 1 or more sites, very carefully, to a depth of 4-6 mm, along a line immediately caudal to the tarsal gland openings, such that 2 layers form, the outer being the skin, orbicularis muscle, and some tarsal glands and the inner being conjunctiva and some tarsal gland (the glands are divided as the incision is made).
GA or heavy sedation; Eyelid margins should never be removed
The inner lid layer (upper or lower lid) must not contain any hairs or hair follicles because the inner layer will be everted toward the cornea after closure
Use 5-0 - 6-0 Vicryll to place 1-2 SI sutures in the apex of each opposing incision
Knot sutures, taking care they do not penetrate the conjunctiva at any point. Once knotted, upper & lower lids become firmly apposed and the outer skin-muscle layer will evert outward, while the conjunctival layer will evert toward the cornea and ends are trimmed very short.
An additional 2-3 horizontal mattress sutures are placed in the now-everted external lid margin layer to further secure the wound edges together.
Initial swelling subsides over a few days
When facial nerve and eyelid function returns, the thin intermarginal membrane that forms after healing can be gradually snipped opened w topical loca/ sedation as needed. If mild lid paresis remains; the temporal 5-10 mm of the lids should be left adhered together
Principles for eyelid lacerations
Clean & debride
Close in multiple (2-3) layers w 3/0 - 5/0 absorbable suture depending on size
Deepest layer needs to incorporate the thin connective tissue layer of the TARSAL PLATE, then SQ, then skin
First suture v important & needs to appose lid margins perfectly
Regardless of the suture pattern chosen, always ensure sutures do not penetrate full thickness of the eyelid at any point, and knots / ends must be well buried inside of the wound or they will touch the cornea → corneal ulceration
3 layers of the eyelid
Skin
Muscular layer
Palpaebral conjunctiva
Most common eyelid neoplasm in the cow
SCC
