Chapter 125 Emergency Ophtho Surgery Flashcards
Look at this diagram and learn the muscles…
What are the four layers of the eyelid
How are lacerations closed?
Skin, muscular, fibrous, conjunctiva
2 layer closure
What is best predictor of perfect post-op eyelid function following laceration?
Meticulous marginal apposition
When doing a figure of 8 suture to align eyelid margins, what should be used to determine appropriate eyelid margin exit point
Opening of meibomian glands
When shoudl figure of 8 clusure not be used for eyelid apposition
At lateral (or presumably medial) canthus Just do simple interrupted and tie suture ends into mosre lateral sutures so they dont poke into the eye
How is severed NL duct treated
Thread 2/0 Monofilament along duct and affix end away from eye and nose.
Repair any other damage
Leave suture inplace for 2-4 months!
List 3 broad surgical techniques for management of corneal ulcer (and subcategories where necessary)
-
Autografts
- Bulbar conjunctival graft aka Gunderson’s graft
- Corneoconjunctival transposition
-
Corneal allografts
- Penetrating keratoplasty (full thickness)
- Lamellar keratoplasty (partial thickness)
-
Extracellular matrix grafts
- Porcine SIS
- Porcine urinary bladder
List 4 variations of a conjuntival graft
A, Pedicle graft.
B, Bridge graft.
C and D, Island graft.
E, 360-degree graft.
What is a key step in harvesting conjunctival graft and why
Removal of Tenon’s capsule
To reduce tension on graft and reduce post op contracture by Tenon’s fibroblasts (both risk factors for graft dehisence)
What non-sx steps shoudl be performed before conjunctival graft
Ulcer sampling for cytology and culture + susceptibility
What is size of pedicle graft relative to ulcer?
3mm wider
Describe condition
Axially located descemetocele in a dog. Notice the deep stromal walls that stain positively with fluorescein and the lucent, glistening Descemet’s membrane that does not stain positively.
Where is conjunctival graft harvest started, relative to limbus
1mm lateral
What step is performed prior to conjunctival graft suturing
Prep of ulcer bed
- bed swabbed with cellulose or edge of beaver blader to remove any epithelail cells (want graft to heal TO epithelium, not epithelium healing under graft)
If edges melting resect cornea back to healther tossie to allow suture holding
What suture is used to suture corneal graft
8/0 Vicryl (polyglactin 910)
What steps are performed afer cinjunctival graft suturing
Suture scleral donor site and consider temprrary tarsorrhaphy
How long is conjunctival graft left in place
How is remaing scar minimised
6-8 weeks
Short course topical roids
What is rule of thumb re conjunctival pedical graft arm angle
Shouldnt exceed 45º from vertical to minimise shear stress form blinking (risk for dehisence)
List 3 rosk factors for conjunctival graft dehisence
- Tenons capsuel tension
- Fibrosis from tenons capsule fibroblasts
- Angle >45º from vertical –> shear forces from blinking
What procedure has been performed
Corneoconjunctival transposition immediately after surgery. Notice that the limbus has been shifted toward the corneal axis in the area of the graft.
What is benefit of corneoconjunctival transposition over conjunctival graft
Allows for clear corneal axis
What is sixelimitation for performing conrenoconjunctival transposition
5mm and must be axial
At what stromal level is conrneoconjunctival transposition performed/
Half stomal
What corneal lesions are particularly suited to corneal allograft?
>6mm
or
Already perforated
N.B. corneal allografts and biosynthetic grafts can be covered with a conjunctival graft after if necessary, just NB
What counts as a freshly harvested corneal graft?
What si the advantage?
Fresh if <35d old and stored at 4ºC in storage medium
More likely to remain clear
Transplanted corneal tissure canbe either full or partial thickness - whatare the names for these procedures?
- Partial thickness = lemellar keratoplasty
- Full thickness = penetrating keratoplasty
What IOP has to be reached to cause corneal/scleral tear?
7000 mm Hg
Where do dog and cat globes tend to ruputre
At posterior pole or near optic nerve
What si it called when sclera tears but conjunctiva remains intact
What is a clue to its presence
OCCULT SCLERAL RUPTURES
Haemorrhagic chemosis and hyphema and low IOP in globe thats experienced blunt trauma
What 2 factors in corneal laceration –> worse progosis
- From blunt trauma (vs sharp)
- If lesion extends beyond limbus (i.e. liekly damage for uveal/retinal tissue)
Name a technique to create corneal ‘seal’ if tissues too macerated to hold more sutures
Deliberately instill some airbubbles –> surface tension provides seal for 1-2d while fibrinous seal forms
WHAT IS TIME LIMIT FOR BEING ABLE TO PRESERVE HERNIATED IRIS TISSUE?
<12 HOURS
What is problem with anterior lens lux
Anterior uveitis, secondary glaucoma, retinal detachment
List 2 management options for anterior lens lux
- Lens extraction
- “Couched” into position behind lens + latanoprost to keep iris consticted
List 3 methods to extract an anteriorly luxated lens
- Phacoemulsification
- Use of lens loop
- 1mm nitrous oxide probe tip to freeze lens to probe whiel being extracted
(extraction via dorsal inscision (09.30 - 02.30)
What addidonal procedure might be performed after extraction of luxated lens?
Placement of artificial lens (placement of pseudophakos)
What are the two methods for securing psuedophakos?
Ab interno suturing
Ab externo suturing
How is proptosed globe managed?
Assess for rupture/laceration
Clean + lubricate
Reducue by pre-placign temporary tarrshoraphy sutures, then use sutures + handle end of scalpel blade behind sutures to reduce globe (can do lateral canthotomy if nec)
Maintain tarrshorraphy for 3 weeks
Describe an emergency way to manage galcuoma if medical tx not wokign
Temporary keratostomy
- i.e. 30G needle instered into anterior chamber, allwoed to leak out until IOP 10 - 15 mmHg
- When done withdraw needle half way through corneal (to allow interior part to seal, wait 5 seconds, then withdrawl fully
