LA Surgery
Terms
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- Know anatomy of eye
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1. Eyelids-obicularis oculi muscle, tarsal plate, palpebral conjunctiva
2. Conjunctiva-palpebral and bulbar
3. Tear film-outer oil layer, middle aqueous layer, inner mucin layer.
4. Cornea, limbus, sclera
a. Cornea-epithelium, stroma, Descemet’s membrane, endothelium
5. Iris and Ciliary Body (Anterior Uvea)-pupil, corpora nigra (granula iridica)
6. Choroid (Posterior Uvea)-tapetum
7. Lens
8. Vitreous
9. Retina-photoreceptor layer-primarily rods in horse, ganglion cell layer
10. Optic nerve - Sedation used for Ophthalmologic exam- Horses
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-Xylazine for minimally invasive
-Detomidine for longer sedation/analgesia
-Xylazine + Torb= more time but "Torb 2 twitch" may cause mvmts! - Sedation used for minimally invasive ophth exam- Cows
- Xylazine
- Names for diff globe sizes
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Phthisis bulbi (shrunken)
Buphthalmia (enlarged) - Dazzle response
- Bright light shined = blink
- PLR
- Fxn of retina, optic nerve, midbrain, oculomotor n., iris, both pupils should constrict
- Eye- C & S
- Cultures taken from corneal, conjunctival or eyelid margin prior to adding anything to eyes
- Instruments needed for Dark room exam- ophtho.
- Transilluminator, direct ophthalmoscope w/ slit aperture, indirect lens, small hand held slit lamp, tonopen
- Tropicamide 1%
- Used to dilate pupil for exam of posterior structures, takes 20 mins, lasts 12 hrs
- Eyelid block- Horse
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Frontal n.- 3-4 ml of LA into supraorbital foramen (sensory to upper lid)
-Palpebral n. 3-4 ml of LA along lateral aspect of highest ptn of zygomatic arch midway b/t lateral canthus and base of ear blocks motor to orbicularis oculi
-LA may be infused along orbital rim at the medial, lateral, and ventral aspects to block sensory innervation to these areas - Eyelid block- Cow
- -Palpebral n. blocked w/ 5-10ml LA SQ along zygomatic arch beginning at the level of the lateral canthus and continuing cd-ly for ~4cm