CATARACT Flashcards
Cataract surgery description
CENIP SI
Cataracts are opacification of the crystalline lens of the eye causing blindness.
Extracapsular or Phacoemulsification techniques
Next, the softer and more peripheral cortical lens material is removed via aspiration. This leaves the posterior capsular bag intact and able to support an intraocular lens (IOL) implant.
IOL implants are made of either silicon, acrylic, or polymethylmethacrylate.
Silicone and acrylic are both foldable and therefore are the most used to allow for a smaller incision for insertion. If necessary, the incision is closed with nylon or vicryl sutures to ensure a watertight seal.
What is the Extra capsular technique?
Extracapsular technique is the removal of the
opacified crystalline lens via an opening made in the anterior lens capsule.
The removal of the lens nucleus can then be extracted intact with a 8-10mm corneal incision, or via phacoemulsification in which ultrasound is used to fragment the lens, and the fragments are then aspirated
What is Phacoemulsification?
Phacoemulsification allows for the procedure to be done with a smaller corneal incision, ~3mm, and results in fewer adverse events.
What if the capsule is unable to support the IOL
If the capsule is unable to support an IOL, the lens is then sutured in the posterior chamber behind the iris.
Another option for IOL
Another option is for the IOL to be placed in the anterior
chamber in front of the iris.
Position:
Supine with table rotated 90-180 degrees. Make sure there is no pressure on the ulnar nerve at the elbow. Be sure that the arm is strapped to prevent slipping with position changes and there is nothing under the arm to cause pressure issues.
Anesthetic positional consideration hemodynamics changes in HR, PVR and FRC
In supine position, the cardiac system has increased right-sided filling and CO, decreased
HR and PVR. FRC is decreased and may fall below closing volume in older patients.
CATARACT ABT (GFS)
Subconjunctival cefazolin 50-100mg or gentamicin 20-40mg or a topical fluoroquinolone
Duration of cataract
15-60
NPO status for cataract
NPO status varies depending on physician. Some prefer strict NPO status while others will allow a light breakfast for a morning surgery with clear liquids up to the time of surgery. If anesthesia is involved, then we will assume that standard NPO times of 6h prior to procedure will apply.
Induction or premed
1mg of versed and 50mcg of fentanyl IV for anxiolytic.
Topical anesthesia for cataracts
using preservative free options (e.g.,
2-4% lidocaine, 0.75% levobupivacaine, 1% ropivacaine, or 1%oxybuprocaine)
Local anesthesia use to
This is used to block the trigeminal nerve endings of the cornea and conjunctiva.
Anesthesia to the
Iris and ciliary body is dependent upon the penetration of the local anesthetic into the anterior chambers. In patients that the anesthesia is unable to penetrate deep enough, additional anesthesia may be required. This can be achieved with intracameral injection with 1% lidocaine or in rare cases may require systemic analgesic and sedatives.
Topical anesthesia may
not be appropriate for all cases due to a lesser degree of analgesia and no akinesia of the ocular muscles.
Subtenon Block (SCTL) Dose
-Sub-Tenon block provides profound analgesia, but motor movements of the globe may still be present. This is performed between the rectus muscles of the globe.
Conjunctiva is incised,
Tenon tissue is elevated and incised, and a short cannulais inserted into the sub tenon space.
Local anesthetic is injected with a posterior spread. Dose is usually 3-4cc of 2% Lidocaine.
Larger doses of up to 10cc can reportedly achieve akinesia.
Is the most effective block for anesthetic distribution throughout the orbit. Pa. C
Intraconal or retrobulbar block
Retrobulbar Block
This block anesthetizes CN III, IV, and VI.
Retrobulbar Block PROCESS expalin
P2AP
PT instructed to look up and nasally a 23g retrobulbar dull needle is inserted through the skin in the infratemporal area, just above the inferior orbital rim and advanced towards the orbital apex 35mm deep into the musclecone/retrobulbar space.
2-4cc of anesthetic solution is then injected into the muscle cone after negative aspiration.
After the injection, the eyelids should be closed, and digital pressure is applied over the globe to the orbit. After a few moments the eyelids should be opened, and the globe is inspected for akinesia
Complications of this RETROBULBAR block are trauma to (OGB)
trauma to the optic nerve, the globe, and blood vessels. All of which =vision loss. CSF = respiratory arrest. Intravascularly = seizures.
Oculocardiac reflex is a
If
decrease of HR by 10% or more following a trigger via traction on the extraocular muscles, direct
pressure on the globe, ocular manipulation, ocular pain, or pressure associated with local infiltration during a retrobulbar block.The afferent limb = trigeminal nerve. The efferent limb = vagus nerve which travels to the heart and decreases output from the SA node.
if Oculocardiac reflex occurs, (SOPI)
stop orbital stimulation
optimize oxygenation and ventilation, and
prevent light anesthesia.
If arrhythmia/bradycardia does not respond, consider atropine 20mcg/kg or glycopyrrolate.
Cataracts POST OP issues
Prolonged exposure to high concentrations of local anesthetics can be toxic to the corneal epithelium and retina. This can result in delayed wound healing and corneal erosion.
Corneal abrasion, photophobia, N/V, and diplopia are other possible complication.
