Opthalamic PPT Flashcards
(142 cards)
1
Q
What is the cataract procedure?
A
Involves removing the cloudy lens & replacing it with a plastic intraocular lens (IOL).
2
Q
What is a cataract?
A
The leading cause of treatable blindness in the world.
Defined as opacification of the crystalline lens.
3
Q
What advancements have influenced cataract removal?
A
Several approaches to cataract removal have evolved due to advances in both instrumentation and artificial intraocular lenses (IOL).
4
Q
What are the two techniques for cataract removal?
A
Extracapsular technique and Intracapsular technique.
5
Q
What is the extracapsular technique in cataract extraction?
A
It involves removal of the crystalline lens through a smaller incision made in the anterior lens capsule (capsulectomy).
6
Q
How can the lens nucleus be removed in cataract extraction?
A
It can be accomplished by an 8-10 mm corneal incision or phacoemulsification, which uses ultrasound energy to fragment the lens.
7
Q
What is an advantage of phacoemulsification?
A
The entire procedure can be performed through a smaller clear corneal incision (3 mm in length).
8
Q
What is the purpose of aspiration in cataract extraction?
A
It allows the removal of cortical lens material while leaving the posterior capsular bag intact to support an IOL implant.
9
Q
What can be done if the lens capsule cannot support an IOL?
A
The lens can be fixated with sutures in the posterior chamber or an anterior chamber IOL can be placed in front of the iris.
10
Q
What are the most popular materials for IOL implants?
A
Polymethylmethacrylate, silicon, and acrylic.
11
Q
Why are silicon and acrylic IOLs commonly used?
A
They are foldable, allowing their insertion through a small corneal incision.
12
Q
How is the wound closed after cataract extraction?
A
The wound is closed with nylon or Vicryl suture to achieve a water-tight seal.
13
Q
What happens when small incisions are used in cataract surgery?
A
The wounds are often self-sealing and don’t require sutures.
14
Q
What is the intracapsular technique in cataract extraction?
A
It involves removal of the crystalline lens with its surrounding capsular bag intact.
15
Q
What must be broken during the intracapsular technique?
A
The zonules that normally stabilize and center the lens must be broken.
16
Q
What tool is often used to remove the lens in the intracapsular technique?
A
A cryoprobe is often used to remove the lens from the eye through a large incision.
17
Q
How frequently is the intracapsular technique performed?
A
This procedure is performed infrequently due to the superior visual outcomes of extracapsular techniques.
18
Q
When may the intracapsular technique be indicated?
A
It may be indicated in situations where capsular bag support has been compromised by either trauma or inherited disorders.
19
Q
Why is proper control of IOP crucial in intraocular surgery?
A
Proper control of IOP is essential for procedures like glaucoma drainage surgery, open sky vitrectomy, penetrating keratoplasty, and traditional intracapsular cataract extraction.
20
Q
What is the significance of low-normal IOP before scleral incision?
A
A low-normal IOP is essential before scleral incision to prevent complications such as iris or lens prolapse, vitreous loss, or expulsive choroidal hemorrhage.
21
Q
What is required for complete akinesia during delicate intraocular surgery?
A
Complete akinesia is essential, and nondepolarizing drugs should be administered with monitoring to ensure 90-95% twitch suppression during surgery.
22
Q
Why is maximal pupillary dilation important in intraocular surgery?
A
Maximal pupillary dilation is important for many types of intraocular surgery.
23
Q
How can pupillary dilation be induced?
A
Pupillary dilation can be induced by continuous infusion of epinephrine 1:200,000 in a balanced salt solution, delivered through a small-gauge needle placed in the anterior chamber.
24
Q
What is glaucoma?
A
A condition characterized by elevated IOP resulting in impairment of capillary blood flow to the optic nerve with eventual loss of optic nerve tissue and function.
25
What are the two different anatomic types of glaucoma?
Open-angle and closed-angle.
26
What is open-angle glaucoma?
The elevated IOP exists with an anatomically open anterior chamber angle.
27
What is closed-angle glaucoma?
The peripheral iris moves into direct contact with the posterior corneal surface, mechanically obstructing aqueous humor outflow.
28
What is trabeculectomy?
The most common surgical procedure used to reduce intraocular pressure (IOP) and often utilized after medical therapy has failed.
29
What is created during trabeculectomy?
A drainage fistula is created from the anterior chamber to the subconjunctival space allowing aqueous humor to drain from the eye.
30
What incision is made during trabeculectomy?
An incision is created in the conjunctiva and Tenon’s layer, exposing the underlying bare sclera.
31
What type of flap is created in trabeculectomy?
A partial-thickness (4-5 mm) scleral flap, hinged at the limbus, is created.
32
What is done to the anterior chamber during trabeculectomy?
An incision into the anterior chamber is created at the base of the scleral flap and converted to a sclerotomy by removing a 1x4 mm piece of corneoscleral tissue.
33
What procedure is performed to prevent iris complications during trabeculectomy?
An iridectomy is performed to prevent the iris from entering the fistula and protect against future angle closure.
34
How is the scleral flap closed after trabeculectomy?
The overlying scleral flap is closed with sutures.
35
What is the ultimate aim of retinal surgery?
The ultimate aim of retinal surgery is the preservation or recovery of vision through the restoration of normal posterior segment anatomy.
36
What procedures are involved in retinal surgery?
Retinal surgery involves various procedures alone or in combination, including scleral buckling, vitrectomy, gas-fluid exchange, and injection of vitreous substitutes.
37
What are scleral buckles?
Scleral buckles are silicone rubber appliances sutured to the sclera to indent the eye wall, thus relieving vitreous traction and functionally closing retinal tears.
38
How is the eye accessed during scleral buckling?
This is an external procedure in which the eye may be entered with a small needle puncture through the sclera for drainage of subretinal fluid or not entered at all.
39
What methods are used to establish chorioretinal adhesions around tears?
Cryotherapy or lasers are used frequently to establish chorioretinal adhesions around tears.
40
How is cryotherapy applied?
Cryotherapy is applied to the sclera while a laser is applied with a fiber optic cable introduced into the vitreous cavity during vitrectomy surgery.
41
What is pneumatic retinopexy?
A technique to repair simple detachments by treating retinal tears with cryotherapy and/or laser, along with injecting an expanding gas into the vitreous cavity.
## Footnote
Usually performed in phakic eyes with tears between 9 o’clock and 4 o’clock positions.
42
What is vitrectomy?
An intraocular procedure to reduce traction on the retina, clear blood and debris, and remove scar tissue.
43
How is vitrectomy performed?
Three 20-25 ga openings are made into the vitreous cavity with a myringotomy blade 3-4 posterior to the limbus.
44
What is the purpose of the inferotemporal quadrant opening in vitrectomy?
It is used for infusion of balanced salt solution via a sutured or transconjunctival troche-based cannula.
45
What are the functions of the remaining openings at 9:30 and 2:30 o’clock positions during vitrectomy?
One is used for a hand-held fiber optic light, and the other for insertion of various manual and automated instruments.
46
How is visualization of the retina achieved during vitrectomy?
By using a contact lens, which can be sutured to the eye or held in position by an assistant.
47
What replaces the vitreous and other tissues removed during vitrectomy?
Balanced salt solution.
48
When is a bubble of gas introduced into the vitreous cavity?
During a scleral buckle or vitrectomy for internal tamponade of retinal tears.
49
What are liquid vitreous substitutes used during vitrectomy?
Perfluorocarbon liquids or silicone oil.
50
What is the use of perfluorocarbon liquids?
They are heavier than water and used to unfold the detached retina and facilitate repair of giant retinal tears in the supine position.
## Footnote
They help in reattaching the retina when PVR is present.
51
When is silicone oil used in retinal surgery?
For complex detachments where long-term internal tamponade of retinal tears is necessary to prevent redetachment.
52
What are lasers used for in eye surgery?
Lasers are used to treat a wide spectrum of eye conditions, including diabetic retinopathy, glaucoma, and age-related macular degeneration.
53
What types of lasers are commonly used for ophthalmic surgery?
Commonly used lasers include argon, krypton, diode, dye-tuned, neodymium, and excimer lasers.
54
What is the wavelength of the argon laser?
The argon laser emits blue-green light with a wavelength of approximately 488-515 nm.
55
What substances strongly absorb light from the argon laser?
Light from the argon laser is strongly absorbed by hemoglobin, melanin, and other pigments.
56
How is the argon laser used in retinal detachment surgery?
It is useful to photocoagulate or cauterize pigment epithelium and the adjacent neurosensory retina, creating adhesion between the retina and the wall of the eye to keep the retina attached.
57
What is the therapeutic effect of the argon laser?
The photocoagulative property achieves its therapeutic effect by focal and controlled necrosis of a limited amount of ischemic retina.
58
Can the argon laser be used for retinal vein occlusion?
Yes, the argon laser is used with some efficacy to treat late complications that can develop in the natural history of retinal vein occlusion.
59
What type of laser is used in posterior lens-capsule surgery?
The YAG laser emits light in the infrared range and is useful in posterior lens-capsule surgery.
## Footnote
The YAG laser has high-power density and is efficacious in creating an opening in opacified posterior capsule membranes that develop in 1/3 of cases after phacoemulsification or other extra capsular cataract surgery.
60
What is an excimer laser?
An excimer laser is a form of high-power ultraviolet chemical laser frequently used in delicate refractive surgery (LASIK), commonly referred to as laser corrective surgery.
## Footnote
An excimer laser generally uses a combination of inert gas and a reactive gas.
61
How does an excimer laser generate laser light?
Under appropriate conditions of electrical stimulation, a pseudomolecule called a dimer is generated and can exist only in an energized state, giving rise to laser light in the ultraviolet range.
62
What is the primary function of an excimer laser in surgery?
The excimer laser supplies enough energy to disrupt the molecular bonds of surface tissue through ablation, allowing removal of exceptionally fine layers of surface material with almost no heating or change to neighboring tissue.
63
What is a ruptured globe?
A ruptured globe involves a tear of either the corneal or scleral layers of the eye and can occur in the setting of blunt, penetrating, or perforating trauma.
64
What is the primary goal of surgical repair for a ruptured globe?
The primary goal of surgical repair is to replace extruded intraocular contents, close defects, and remove any foreign body.
65
Why is the complete examination of the eye often delayed?
Complete examination of the eye is often delayed until the patient is in the controlled setting of the OR under GA to reduce the risk of causing further damage.
66
How are anterior injuries identified compared to posterior injuries?
Anterior injuries are easily identifiable while posterior injuries may require extensive exploration.
67
What may be required for extensive exploration of posterior injuries?
Extensive exploration can require a 360 degree opening of the conjunctiva and isolation of each extraocular muscle to allow adequate inspection of the entire scleral surface.
68
What type of sutures are usually used for corneal lacerations?
Corneal lacerations usually are closed with 10-0 nylon sutures.
69
What sutures may be used for scleral tissue?
8-0 nylon or Vicryl may be used for scleral tissue.
70
What triggers the oculocardiac reflex?
The reflex is triggered by pressure on the globe, traction on the extraocular muscles, and the conjunctiva or orbital structures.
71
What are other causes of the oculocardiac reflex?
It can also be elicited by retrobulbar block, ocular trauma, and direct pressure on tissue in the orbital apex after enucleation.
72
What are the afferent and efferent limbs of the oculocardiac reflex?
The afferent limb is trigeminal, and the efferent limb is vagal.
73
What is the most common manifestation of the oculocardiac reflex?
The most common manifestation is sinus bradycardia.
74
What dysrhythmias can occur due to the oculocardiac reflex?
A wide spectrum of dysrhythmias can occur, including junctional rhythm, ectopic atrial rhythm, atrioventricular blockade, ventricular bigeminy, multifocal premature ventricular contractions, wandering pacemaker, idioventricular rhythm, asystole, and ventricular tachycardia.
75
When can the oculocardiac reflex appear?
The reflex may appear during either local or general anesthesia.
76
What factors are believed to augment the incidence and severity of the oculocardiac reflex?
Hypercarbia and hypoxemia are believed to augment the incidence and severity, as may inappropriate anesthetic depth.
77
How can the incidence of the oculocardiac reflex be reduced?
Atropine given intravenously within 30 minutes of surgery is believed to reduce the incidence of the reflex.
78
What is strabismus?
Strabismus is an idiopathic disorder that may be associated with poor vision, cataracts, trauma, neuromuscular disorders, or congenital syndromes.
79
What is the goal of strabismus surgery?
The goal of this procedure is to correct the ocular misalignment caused by strabismus.
80
What does surgical correction for strabismus involve?
Surgical correction involves isolation of one or more of the extraocular muscles with subsequent recession (transection and reinsertion) or resection (shortening) of the muscle.
81
What is the prevalence of strabismus in the pediatric population?
Strabismus has a prevalence of 3-5% in the pediatric population.
82
What is the most common pediatric eye surgery?
Strabismus surgery is the most common pediatric eye surgery performed.
83
What should be assessed in a preoperative assessment?
The patient’s ability to lie flat, exercise tolerance, and any arthritic changes that may affect lying flat.
84
What is the goal for patients under monitored anesthesia care (MAC)?
To have a comfortable, cooperative patient who can lie completely still without falling asleep for 1-2 hours.
85
When is a patient considered to have a full stomach?
If the injury occurred within 8 hours of the last meal.
86
What should be excluded in a patient with a ruptured globe?
Other injuries to the head, neck, or other structures.
87
What type of anesthesia is usually required for children undergoing eye surgery?
General anesthesia (GA) is almost always required.
88
What is important to monitor during procedures?
In addition to standard monitors, maintaining verbal communication with the patient.
89
What type of anesthesia is typically used for short-duration ophthalmic procedures?
Topical or regional anesthesia under MAC.
90
What should be avoided during ocular surgery?
Coughing and movement.
91
What was identified as the most common mechanism of injury during ocular surgery?
Movement, described as coughing and bucking, which resulted in poor visual outcomes.
92
What medications can safely reverse neuromuscular blockade in patients with glaucoma?
Atropine and neostigmine, as they have minimal effects on pupil size and intraocular pressure (IOP).
93
What safety measure should personnel near lasers take?
Wear goggles.
94
Why is regional anesthesia contraindicated in patients with open-eye injury?
Due to increased intraocular pressure (IOP).
95
What is common after strabismus surgery?
Postoperative vomiting.
96
What is the primary concern with retrobulbar or peribulbar blocks?
The primary concern is the risk of further globe extrusion or damage.
97
What do retrobulbar or peribulbar blocks involve?
They involve injecting local anesthetic behind or around the globe, often using a needle.
98
What is the condition of the eye wall in an open-globe injury?
In an open-globe injury, the integrity of the eye wall (cornea or sclera) is already compromised.
99
What may needle insertion or increased orbital pressure from fluid injection cause?
It may extrude intraocular contents (like vitreous or lens), worsen the rupture, or cause permanent vision loss.
100
What are the types of anesthesia techniques mentioned?
MAC, topical anesthesia, regional anesthesia (retrobulbar block, peribulbar block, sub tenon’s block)
101
How is a retrobulbar block performed?
The retrobulbar space is approached from the infratemporal quadrant of the orbit using a 25- or 27-gauge needle. The eye should be in a neutral or downward and medial position.
102
What is the procedure after positioning the needle for a retrobulbar block?
Once the needle is positioned and there is no aspiration of blood or CSF, 3-5 mL of anesthetic solution is injected slowly.
103
What is necessary to prevent eyelid movement during a retrobulbar block?
A facial nerve block is necessary, injecting 4-8 mL of anesthetic solution above and below the lateral aspect of the orbit.
104
What is the most common complication of a retrobulbar block?
Hematoma formation, which can be minimized by using a needle shorter than 31 mm.
105
What are other complications associated with retrobulbar blocks?
Local anesthetic toxicity, development of the oculocardiac reflex, sudden apnea, and obtundation.
106
How is a peribulbar block performed?
5-6 mL of anesthetic solution is injected into the peribulbar space, entering superior to the inferior rim of the orbit at the junction of the lateral and middle thirds of the lower lid, utilizing a 25- or 27-gauge needle.
107
What are the characteristics of peribulbar blocks compared to retrobulbar blocks?
Peribulbar blocks generally have a slower onset and are more likely to cause conjunctival swelling, which may interfere with surgery.
108
How is a sub tenon’s block performed?
Injection of local anesthetic through a 22-gauge cannula into the space below Tenon’s capsule produces ocular anesthesia similar to retrobulbar block.
109
What are the characteristics of sub tenon’s blocks?
Onset is slower, akinesia is less reliable, and the usual injection volume is 3-5 mL, with more necessary if akinesia is required.
110
What is noted about significant complications with sub tenon’s blocks?
Significant complications with the technique are extremely rare.
111
What type of anesthesia is used for repair of ruptured or lacerated globe?
GETA (General Endotracheal Anesthesia) is used for repair of ruptured or lacerated globe.
112
What type of anesthesia is used for strabismus surgery?
GETA or LMA (Laryngeal Mask Airway) is used for strabismus surgery.
113
What is the recommended dose of Midazolam for pre-induction?
1-2 mg iv
114
What do surgeons prefer regarding IOP during retinal reattachment surgery?
A normal IOP
115
What medications may be given to decrease IOP?
Acetazolamide or mannitol
116
What type of premedications should be avoided?
Narcotic premedications
117
What is the reason for avoiding narcotic premedications?
They may increase nausea and possibility of emesis
118
What should be provided to patients prior to surgery?
A detailed explanation of events
119
What is the recommended dose of Metoclopramide for patients at risk of aspiration?
10 mg iv
120
For which patients may Metoclopramide enhance gastric emptying?
Patients with increased risk of aspiration, obese, and/or very anxious patients
121
What is the standard procedure for managing a patient with an affected eye?
Care should be taken not to put pressure on the affected eye with the face mask.
122
What is the recommended approach for repairing a ruptured or lacerated globe?
Perform an RSI with cricoid pressure to protect the airway and prevent increased IOP.
123
What preoxygenation technique should be used for patients with an affected eye?
Preoxygenation should be done while avoiding external pressure on the eye from the face mask.
124
What pretreatment is suggested before intubation?
Administer a nondepolarizing relaxant followed by IV lidocaine and fentanyl.
125
What induction agents are used for intubation?
Induce with propofol and succinylcholine, and intubate with an oral RAE tube.
126
What is the recommended induction method for pediatric patients?
Induction with sevoflurane while maintaining cricoid pressure and intubating when the patient is deeply anesthetized.
127
What medication may be given to attenuate oculocardiac and oculorespiratory reflexes in pediatric patients?
A vagolytic dose of atropine (0.02 mg/kg) or glycopyrrolate (0.01 mg/kg) may be given.
128
How does sevoflurane affect vagally mediated responses?
The use of sevoflurane as an inhalation agent significantly decreases the occurrence of these responses.
129
What procedure may the surgeon perform before using muscle relaxants?
FDT may be performed by the surgeon at this time.
130
What can be used to assist ET intubation after FDT?
Subsequently, NMB can be used to assist ET intubation.
131
What is the standard maintenance technique for anesthesia?
Standard maintenance or TIVA. Avoid hypercapnia which increases IOP.
132
What techniques can be used for strabismus anesthesia?
Techniques can include either inhalation agents or TIVA.
## Footnote
Combination therapy with drugs from different antiemetic drug classes is most effective.
133
What is the risk associated with the use of N2O in anesthesia?
The use of N2O may increase the risk for PONV.
134
What should be continued for post-operative pain management?
Continue acetaminophen and antiemetics as needed; occasional need of opioid analgesics.
135
What are the 5 most important considerations for post-operative management?
1. The common occurrence of PONV requires administration of intraop antiemetics (metoclopramide 10 mg iv and ondansetron 4 mg iv 30 min before end of surgery).
2. IV lidocaine, posterior pharyngeal suctioning combined with a small amount of narcotic may blunt cough reflex prior to extubation.
3. Avoid hypercapnia because it can increase IOP.
4. Humidify gases for pediatric patients.
5. In patients where the risk of GA is unacceptably high, surgical repair can be accomplished using topical anesthesia.
136
Concerns with Various Ocular Procedures
Strabismus repair
Oculocardiac reflex
Oculogastric reflex
Forced duction testing
Malignant hyperthermia
137
Concerns w/ Intraocular surgery
Proper control of IOP
Akinesia
Drug interactions
Associated systemic disease
138
Concerns w/ Retinal detachment surgery
Nitrous oxide interaction with air, sulfur hexafluoride, or perfluorocarbon gas
bubble
Venous air embolism
Oculocardiac reflex
Proper control of IOP
139
Ophthalmic Anesthesia Complications
• Retrobulbar Hemorrhage • Intravascular Injection • Globe Puncture • Optic Nerve Sheath Trauma • Ocular Ischemia • Extraocular Muscle Palsy & Ptosis • Facial Nerve Blocks • Oculocardiac Reflex
140
What is a corneal abrasion?
The most common injury occurring after general anesthesia.
141
What are the believed causes of corneal abrasion?
Believed to result from the drying of the exposed cornea or direct trauma, such as an anesthesia-mask injury.
142
How can corneal abrasion be prevented during anesthesia?
Ensuring that the eyelids are closed & secured with tape should provide satisfactory protection of the cornea.
