Innovative Techniques in Ophthalmology Ashok Garg, I Howard Fine, Ioannis G Pallikaris, Hiroshi Tsuneoka
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1Cataract Surgery and Related Technologies (MSICS, Microphaconit, Minimally Invasive Cataract Surgery)
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2

Ocular Anesthesia in MICS1

  • ANESTHESIA FOR MICROPHACO
  • LOCAL ANESTHESIA
Ashok Garg (India), Franciso J Gutiérrez-Carmona (Spain)4
 
INTRODUCTION
Anesthesia for Cataract Surgery has undergone tremendous changes and advancements in last century (Table 1.1). In 1846 general anesthesia techniques were developed which were not found suitable and satisfactory for ophthalmic surgery. In 1884 Karl Köller discovered surface anesthesia techniques using topical cocaine for cataract surgeries which found favor with the ophthalmologists. However due to significant complications and side effects of cocaine this technique was abandoned.
Also in 1884 Herman Knapp described retrobulbar injection as local anesthetic technique for ocular surgery. He used 4 percent cocaine solution injected into the orbital tissue close to posterior part of the globe to achieve adequate anesthesia but in the subsequent injections patients experienced pain. In 1914 van Lint introduced orbicularis akinesia by local injection to supplement subconjunctival and topical anesthesia. However this technique found favor only after 1930 when procaine (Novocaine) a safer injectable agent made it feasible.
Table 1   Evolution of anesthetic techniques for cataract surgery
Techniques
Years
Authors
General anesthesia
1846
Morton
Topical cocaine
1884
Köller
Injectable cocaine
1884
Knapp
Retrobulbar (4% cocaine)
1884
Knapp
Orbicularis akinesia
1914
Van Lint, O'Brien, Atkinson
Hyaluronidase
1948
Atkinson
Posterior peribulbar
1985
Davis Y Mandel
Limbal
1990
Furata and coworkers
Sub-tenon anesthesia
1990
Hansen
Anterior peribulbar
1991
Bloomberg
Subconjunctival
1991
Petersen
Topical anesthesia
1992
Fichman
Pinpoint anesthesia
1994
Fukasaku
Topical plus intracameral
1995
Gills
No anesthesia
1998
Agarwal
Cryoanalgesia
1999
Gutiérrez-Carmona
Xylocaine jelly
1999
Koch, Assia
Hypothesis, no anesthesia
2001
Pandey and Agarwal
Viscoanesthesia
2002
Werner, Pandey, Apple
With the development of hyaluronidase as an additive to the local anaesthetic solution Atkinson in 1948 reported that large volumes could be injected with less orbital pressure and improved safety injections into the cone (retrobulbar) were recommended and gained rapid favor becoming anesthetic route of choice among ophthalmologists.
In Mid 1970s, Kelman introduced an alternative technique of local anesthesia for ocular surgery known as peribulbar injection. However till 1985 this new technique was not published in ophthalmic literature. In 1985 Davis and Mandel reported local anesthetic injection outside the cone into the posterior peribulbar space (periocular).
Further modifications of both retrobulbar and periocular injection techniques were made by Bloomberg, Weiss and Deichaman, Hamilton and colleagues, whitsett, Murdoch Shriver and coworkers. These modifications consisted of more anterior deposition of anesthetic solution with shorter needles and smaller dosages.
With the introduction of small incision cataract surgery, phacoemulsification and other microsurgical procedures in ophthalmology, use of shorter needles with smaller dosages became more common. Fukasaku and Furata et al reintroduced subconjunctival anesthetic techniques. Fichman in 1992 first reported the use of topical tetracaine anesthesia for phacoemulsification and intraocular lens implantation starting an era of topical anesthesia in ocular surgery.
With the advent of many ocular anesthetic techniques in past two decades indicates the need for the development of an ideal anesthetic and technique for ocular surgery. Every existing technique has its own advantages and disadvantages. General anesthesia for cataract surgery is virtually out of favor with ophthalmologists. Retrobulbar anesthesia, periocular (peribulbar, sub-conjunctival, sub-Tenon or parabulbar, orbital and epidural) and topical Anesthesia or a combination of peribulbar and topical are being used in present day ocular surgery.
Now with the advent of under 1.0 mm incision technique, foldable and rollable intraocular lenses, no anesthesia cataract surgery is becoming increasingly 5popular, this technique was designed by Agarwal (India) in 1998.
In 1999, Gutiérrez-Carmona (Spain) designed the cryoanalgesia technique for cataract surgery modifying Agarwal's method.
 
ANESTHESIA FOR MICROPHACO
Microincision cataract extraction may be performed under general anesthesia, local anesthesia or topical anesthesia, depending upon condition of patient cataract status and surgeon choice.
Usually for microphaco general anesthesia is not given. It is advisable only in highly anxious/nervous patient or when cataract surgery requires a long time for completion. Patients who are extremely apprehensive, deaf, mentally retarded, unstable or cannot communicate well with the surgeon are more suitable for general anesthesia. General anesthetic facilities with expert anesthetist are mandatory.
Local anesthesia in microphaco have superseded general anesthesia due to their indisputable advantages, such as the potential for ambulatory surgery, rapid recovery and lack of complications. However local anaesthetic surgery using the retrobulbar or peribulbar technique is not without possible complications, such as perforation of the eyeball accompanied by retinal detachment and severe intraocular hemorrhage, retrobulbar hematoma, diplopia, direct optic nerve trauma caused by the retrobulbar needle, increased intraocular pressure, postoperative ptosis, or systemic complications such as accidental administration of anesthetic to the bloodstream or nervous system.
Moreover, in the last decade, topical anesthesia in microphaco has gained more interest on the part of surgeons as it eliminates the risks involved in using general and local anesthesias. However, this method should be performed by an expert surgeon who has mastered the technique and who can perform it rapidly. No anesthesia microphaco surgery is also becoming popular among ophthalmologists worldwide.
 
LOCAL ANESTHESIA
Local ocular anesthesia is the mainstay of microphaco. Local anesthesia minimizes the risk of wound rupture a complication frequently associated with coughing during extubation and postoperative nausea and vomiting (in general anesthesia) (Figure 1.1). Generally the use of 1:1 mixture of 2 percent xylocaine and 0.50 percent bupivacaine alongwith adrenaline and hyaluronidase in facial, retrobulbar and peribulbar blocks achieve rapid Anesthesia, akinesia and postoperative analgesia for several hours.
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Figure 1.1: Diagrammatic surface distribution of sensory nerves. Note branches derived from ophthalmic nerve (V1) and maxillary nerve (V2) a division of the trigeminal nerve
On the other hand, we have sub-Tenon or parabulbar anesthesia performed with a blunt cannula which avoids the complications arising from the use of needles. Intraoperative analgesia and akinesia are similar to the peribulbar technique.
Care should be taken to avoid intravascular injections of anesthetic agents because refractory cardiopulmonary arrest may result from an inadvertent intravenous or intra-arterial injections.
Many patients express pain of facial and retrobulbar injections and other complications so these techniques are now out of favor.
Out of various local anesthesia techniques available today, only following techniques are commonly used for microphaco surgery.
 
Peribulbar (Periocular) Technique
Since the exit of retrobulbar akinesia, peribulbar akinesia is considered a safe and effective technique of local anesthesia for microphaco. It is method of choice with eye surgeons for giving local anesthesia to cataract. As the name indicates, peribulbar anesthesia is a technique in which a local anesthetic is injected into peribulbar space and is not aimed at blocking a particular nerve.6
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Figure 1.2: Needle positions for peribulbar and retrobulbar akinesia(Courtesy: Ciba Geigy clinical symposia)
 
Technique
Periocular anesthesia is administered at two sites: lower temporal quadrant and nasal to caruncle (Figure 1.2).
The required local anaesthetics are lidocaine 1 percent and bupivacaine 0.75 percent with hyaluronidase. Bupivacaine is preferred as it is a longer acting anesthetic agent which can provide prolonged anesthesia and analgesia.
In the first stage, injection of 0.5 cc of 1 percent lidocaine with a 26 gauge needle is done under the skin at about 1 cm away from the lateral canthus in the lower lid, along the orbital rim. The same needle is passed deeper to inject 0.5 cc of lidocaine into the orbicularis muscle and 1.0 cc into the muscle sheath. A second injection is done in the similar fashion in the upper eye lid just below the supraorbital notch. Pressure is applied at both for a minute using gauze pieces.
In the second stage, combination of 6.0 ml of 0.75 percent bupivacaine, 3 ml of 1 percent lidocaine and 0.25 cc of hyaluronidase is filled into a 10 ml disposable syringe fitted with a, 1-1/4 inch 23 gauge, hypodermic needle. The needle is first introduced deep into the orbit through the anesthetized site in the lower eyelid. One ml is injected just beneath the orbicularis muscle and then the needle is advanced up to the equator of the globe to inject 2 to 3 ml of the solution. The same procedure is followed in the upper nasal quadrant through the preanaesthetized site to inject 1 ml and another 1 ml may be injected around superior orbital fissure, by deeper penetration.
At the end of the procedure, fullness of the lids is noted due to the volume of the injected. Firm pressure with the flat of the hand is applied over the globe and is main tained for a minute. Then, before surgery, any pressure device as per the surgeon's choice like Honan's balloon, super pinky ball, balance weight or simple pad-bandage is applied for 20 to 30 minutes, to achieve the desired response of hypotony.
The efficacy of the anesthesia is evaluated after about 10 minutes of injection and if inadequate, 2 to 4 ml more can be injected. In case of persistent inferior or lateral movement injection lower temporal quadrant and in case of persistent movements upwards of nasally, the upper quadrant could be infiltrated in the same fashion.
Hyaluronidase is essential as it helps in the spread of the drug. Otherwise, there are chances of the eye being proptosed due to high orbital pressure induced by the large quantity of the fluid injected.
Single injection of 5 to 6 ml of anesthetic mixture injected from any site posterior to equator of the globe also achieves same results. For convenience, however, it may be done through lower lid the junction of lateral and middle one-third, along the floor of the orbit.
Adequacy of akinesia is determined by the absence of ocular movements in all directions.
This technique is certainly better than retro-ocular technique and has least complications.
 
Advantages
The advantages reported are:
  1. The injection is done outside the muscle cone and so, the inherent complications of passing the needle into the muscle cone is comp letely eliminated.
  2. It does not enter the retrobulbar space and thereby avoids retrobulbar hemorrhage, injury to optic nerve and entry of anesthetic agents into subarachnoid space and other complications like respiratory arrest.
  3. Since the needle is constantly kept parallel to the bony orbit, it avoids injury to globe and entry of anesthetic agents into the eyeball.
  4. It causes less pain on injection.
  5. The procedure is easier and can be performed without causing damage to vital structures.
  6. It does not reduce vision on table.
  7. No facial block is required.
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Drawbacks
The possible drawbacks of this procedure are:
  1. Chemosis of conjunctiva.
  2. Delayed onset of anesthetic effect and
  3. Potential risk of orbital hemorrhage. Though it occurs rarely, the magnitude of the problem is comparable to retrobulbar hemorrhage and necessitates postponement of surgery.
 
Mechanism
The exact mechanism is not known but this procedure may best be described as ‘Infiltration Anesthesia’ where nerve endings in all tissues in the area of injection get anesthetized.
Peribulbar anesthesia is a safe and reliable technique for achieving akinesia and anesthesia of the globe.6 In case of inadequate anesthesia, repeat injections in the similar manner can be safely used to achieve the purpose.
Superior rectus injection The induction of temporary paralysis of the superior rectus muscle is essential for any intraocular operation where the surgical field is upper half of the eye. This injection also affects the action of levator palpebrae superioris.
In this injection patient is asked to look down. The upper lid is retracted and 2.5 cm long needle is passed into Tenon's capsule at the temporal edge of the superior rectus muscle. The needle is directed posteromedially and about 1 ml of anesthetic mixture of 2 percent xylocaine is injected around the muscle belly behind the equator. This injection can also be made through the skin of the upper orbital sulcus.
Tenon's capsule injection The Injection of anesthetic mixture can be given into Tenon's capsule around the upper half of the eyeball and into the belly of superior rectus muscle. It is considered safer than the retro-ocular injection across the post-ganglionic fibers of the cillary body and may be effective in inducing extraocular muscle akinesia.
 
Parabulbar (Flush) or Sub-Tenon Akinesia
This is a very valuable alternative technique to the retro and peribulbar methods. In this technique, we attempt to place the anesthetic in the intraconical space, near the ciliary ganglion. This method consists of a limbal sub-Tenon administration of retrobulbar anesthesia using a blunt irrigating cannula (Figures 1.3 and 1.4).
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Figure 1.3: Parabulbar (flush) local anesthesia (cross-section view)
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Figure 1.4: Parabulbar (flush) local anesthesia (surgeon view)
8
This technique can be used for anterior and posterior segment surgery.
 
Technique
We use a blunt or Greenbaum cannula with the anesthetic or mixture chosen. The patient needs to look up and in the direction of the eye to be operated on so that we can see the inferior nasal quadrant. We place topical anesthesia and next we perform an conjunctival and Tenon incision with Wescott scissors creating a deep tunnel. We introduce the blunt cannula through the tunnel, injecting the anesthetic. After, we place a Honan's balloon or super pinky decompressor for 10 minutes at 30 mm Hg.
 
Complications
Retrobulbar hemorrhage This can be produced when we perform the mucous-Tenon dissection, or when we introduce the cannula through the tunnel or when we vary this technique by using a continuous infusion with catheter.
Conjunctival edema This is produced when we inject the anesthetic in the subconjunctival space and not in the sub-Tenon space, diminishing the possibility of achieving complete denervation of the eyeball.
Hyposphagma This is frequently produced postoperatively, leading to undesired aesthetic results.
 
Topical Anesthesia
Since the advent of retrobulbar and peribulbar techniques in the early part of this century, both procedures are mainstay of local anesthesia for intraocular surgery till today. They do carry the risk of perforation of globe, optic nerve and the inadvertent injection of anesthetic at wrong places.
These accidents are mainly due to:
  • Carelessness on the part of ophthalmologist who considers the procedures lightly and occurs more often with senior eye surgeons
  • Using long needles for these techniques endangers the perforation of globe, piercing the optic nerve and entering crowded retrobular space and even touching the intracranial space on forceful injection of copious amounts
  • Anesthetics given through local injection with little knowledge of anatomy of this area
  • Retrobulbar hemorrhage with its adverse effects on nerve and globe is very common complication of this technique
  • Injury caused by perforation of globe can lead to hole formation, retinal detachment, vitreous hemorrhage and central and branch vein occlusions.
To overcome all these practical difficulties use of topical anesthesia in intraocular surgery has been widely suggested and used at an international opthalmic level.3 Topical anesthesia meaning topical application of 4 percent xylocaine or 0.5 to 0.75 percent proparacaine one drop 3 to 4 times at regular intervals in the eye has become increasingly popular and accepted.7 In present day high tech intraocular surgery specially phacosurgery topical anesthesia is the anesthesia of choice with the eye surgeons world wide.
 
Indications to use Topical Anesthesia
  • Its indications in intraocular surgery are mainly when performing phacoemulsification and IOL implantation through a clear corneal tunnel and corneoscleral incisions
  • Topical anesthesia is ideally suited for small incision and stitchless cataract surgery. However, it is not a advocated to perform standard/manual extracapsular cataract extraction and IOL implantation
  • Proper selection of patient is of great importance in this technique. It is important to have a patient who will comply with the instructions given during surgery.
  • Patients who are non-cooperative, hard of hearing, with language problem and anxious patients are poor candidates for surgery under topical anesthesia. Capsulorhexis requires the maximum cooperation of the patient
  • Intraocular surgery likely to be problematic in patients with rigid small pupils responding poorly to dilating drops and eyes with lenticular subluxation and high grade nuclear sclerosis are relative contraindications for topical anesthesia
    9
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    Figure 1.5: The assisting nurse places anesthetic drops in order to achieve topical anesthesia
  • Eye surgeon operating with topical anesthesia should be proficient and experienced at phacoemusification
  • This procedure requires the use of foldable IOL either as a silicone lens or an acrylic lens. This is essential because corneal tunnel suture lens incision cannot be larger then 3.5 mm. Otherwise corneal complications may arise and the incision would not be self-sealing.
How to achieve surface anesthesia for intraocular surgery Generally 3 applications of 4 percent xylocaine or 0.4 percent benoxinate HCl or 0.5 to 0.75 percent proparacaine 10 minutes apart starting 30 minutes before surgery are recommended (Figure 1.5). A drop is thereafter instilled prior to the incision. 1 cc of 4 percent xylocaine or 0.4 percent benoxinate HCI or 0.5 to 0.75 proparacaine (from fresh vail) is drawn into sterile disposable syringe and OT staff person is asked to instil a few drops of the same prior to cauterization of bleeders and if required during surgery conjunctival anesthesia is used (pinpoint and mini pinpoint surface anesthesia).9
Apart from giving topical anesthesia one has to give systemic analgesia. Besides it, surgeon should have a commanding hypnotic voice (vocal local anesthesia).
  • Most surgeons doing corneal tunnel incision under topical anesthesia prefer to do it from temporal side.
Can one convert half way through surgery under topical anesthesia?
Intraoperative conversion from topical to peribulbar anesthesia can definitely be achieved if surgical situation warrants it. Since corneal tunnel incision is sutureless and self-healing a peribulbar injection can safely be given during the surgery.
 
Advantages of Topical Anesthesia
  1. Phacoemulsification experts feel that use of topical anesthesia with a clear corneal tunnel self-healing incision is a significant advancement in intraocular surgery. With topical anesthesia visual recovery is immediate.
  2. It prevents the well known complications of retrobulbar and peribulbar injections as mentioned in the early part of this chapter.
  3. It lessens the time of operating room use thereby lowering costs.
  4. There is no immediate postoperative ptosis as seen in retrobulbar or peribulbar and van Lint, O’Brien infiltrations lasts for 6 to 8 hours due to temporary akinesia of the lids.
  5. With topical anesthesia photon laser intraocular surgery can be OPD procedure.
  6. Faster visual recovery and ability for patients to remain on anticoagulation therapy.
  7. In practice we have seen the anxiety of patients to peribulbar and retrobulbar injections prior to surgery. With topical anesthesia this problem is over and patient compliance will be better during intraoperative period.
  8. There is no need for a qualified anesthesiologist in the operating theater during the operation, although a number of ophthalmologists prefer an anesthesiologist by their side for local anesthesia (retrobulbar and peribulbar anesthesia).
  9. No risk of postponement of intraocular surgery as seen in cases of retrobulbar hemorrhage.
Again its main advantages is that it provides for immediate postoperative visual recovery.
 
Disadvantages of Topical Anesth esia
  1. Only a highly experienced surgeon can operate with topical anesthesia. The eye can move which makes 10the operation more difficult. If the eye movement occurs when capsulorhexis is being done, an undesirable capsular tear may take place leading to failure of this important step of the operation.
  2. The chances of intraoperative complications with topical anesthesia can be high if the surgeon is not highly skilled. If such complications arise surgeon should be ready to convert to other methods of local anesthesia during the intraoperative stage, because topical anesthesia along may not be adequate to handle intraoperative complications. Surgeon should be of cool temperament who can handle such a situation without anxiety.
  3. Topical anesthesia is not indicated in all patients specially in anxious stressed patients, people with hearing difficulties, children and very young patients.
  4. As in our country a large number of patients come from rural areas who are illiterate and poor. Their compliance remains very poor and they do not respond adequately to the command during surgery with topical anesthesia.
  5. The presence of very opaque cataract is a contra indication to the use of topical anesthesia. This is because surgeon depends on the patient ability to visually concentrate on the operating microscope light in order to avoid eye movement during the operation. Patients, who are not able to fix the eyes, may lead to complications.
  6. Some patients may feel pain during surgery with topical anesthesia. One patient observed a lot more pain and felt as if a sword was being used to cut him up. The pain continued postoperatively for quite some time.
  7. In principle, adequate selection of patients is fundamental when considering the use of topical anesthesia.
In spite of these hurdles topical anesthesia will be a safe and common technique for local anesthesia during intraocular surgery in the near future.
 
Intracameral Anesthesia
This an adjunct method with topical anesthesia designed by Gills in 1995. This results in the blocking of the sensitivity in t he long ciliary nerve branches, so that the zonular stretching and the scraping of the iris during phacoemulsification do not produce discomfort in the patient.
This technique consists of injecting 0.1 ml of 1 percent preservative-free lidocaine in the anterior chamber, avoiding the risk of intraocular toxicity and achieving a good analgesia of the iris.
Topical and intracameral anesthesia can be used in patients treated with anticoagulants.
Studies by some authors comparing topical and topical plus intracameral anesthesia have demonstrated that neither topical nor topical plus intracameral anesthesia result in important differences in patient complaints or in complications.11 However, the use of intraoperative lidocaine is safe and effective in controlling intraoperative discomfort.10
 
No Anesthesia Cataract Surgery
This non-pharmacological technique was first carried out by Amar Agarwal (India) in 1998.1 Neither topical nor intracameral anesthetics agents are used.
 
Technique
  • Before performing the surgery, we must inform the patient that he will feel contact and that he can move his eyes
  • Use a speculum such as Castroviejo, Clarke or Liebermann
  • Viscoelastic HealonÒ is injected into the anterior chamber using a needle through the area where the second (paracentesis) site is made
  • A straight rod is used to stabilize the eye with the left hand
  • With the right hand, a 3.2 mm groove is made in clear-temporal cornea using a diamond knife (Figure 1.6)
  • A 5.0 to 5.5 mm wide capsulorhexis is performed using a 26 gauge bent needle cystotome
  • Hydrodissection is performed with BSSÒ
  • Phacoemulsification is performed using the karate chop technique using less ultrasound power to avoid excessive heating of the phaco tip, which in turn can produce pain11
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    Figure 1.6: The surgeon's right hand making a clear corneal tunnel incision in the temporal quadrant
  • Cortical washing. First, try to remove the subincisional cortex as that is the most difficult
  • Viscoelastic injection in the capsular bag and a foldable one-piece plate IOL is implanted
  • The viscoelastic is removed from the anterior chamber and the capsular bag by irrigation
  • Closure of the corneal incisions by stromal hydration.
The microscope light should begin at the lowest level and gradually increase in intensity. The intensity of the light should increase to normal levels after performing the hidrodissection and the patient should be told to look at the light during surgery.
The skill and experience of the surgeon is one of the most important factors for the No Anesthesia Cataract Surgery. While using this technique, it is important to avoid grasping the conjunctiva or sclera with tooth forceps. The surgeon should use a straight and relatively blunt rod to stabilize the eye during the entire procedure.
As with topical Anesthesia, we should minimize the iris-lens-diaphragm movement and iris manipulations.
No subconjunctival injections should be made following surgery nor should an eyepad be placed.
 
Microphaco Surgery with Cryoanalgesia
This non-pharmacological Anesthesia technique was designed in 1999 by Francisco J. Gutiérrez-Carmona (Spain). There are no anesthethic drops used, it is a modification of No Anesthesia Cataract Surgery.
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Figure 1.7: A monolateral eye mark of cold gel is placed over the eye before surgery for about 10 minutes
 
Technique
  • Before performing the surgery we must tell the patient that he will feel a cold sensation in his eye and that he can move his eyes
  • In order to perform the surgery, it is necessary previously to cool all fluids to be used in the operation to around 4 degrees Celsius, except for the povidone drops, which should be at normal temperature for optimum effect
  • Before surgery, an eye mask of cold gel (Eyes Pack Single) is placed over the eye for about ten minutes (Figure 1.7). This will afford some degree of analgesia to the eyelids, facilitating the insertion of the lid speculum
  • Ocular asepsis before surgery is achieved using 5 percent povidone drops. Next, a drop of cold methylcellulose (Celoftal) is instilled in the eye before placement of the ophthalmic drape to isolate the eyelid. The cold Celoftal reduces the stinging sensation of the povidone
  • The cornea is previously cooled by continuous irrigation from a flask of cold BSS® in the area in which the paracentesis will be conducted. To perform the paracentesis, the eyeball is held still with a spatula or lens manipulator placed on the corneal periphery 12opposite the area where the anterior chamber (AC) is accessed using a parac entesis knife
  • Cold viscoelastic material (Viscoat®) is injected through the paracentesis into the anterior chamber, and a lens manipulator is subsequently introduced to stabilize the eyeball
  • The cornea is then continuously cooled with BSS® in the area in which the clear corneal incision is to be made. Corneal tunnel incision is performed at 90º to the paracentesis with the help of a a 3.2 mm phaco knife
  • Cold Viscoat® is injected into the anterior chamber. Next, the corneal incision is chilled with cold BSS® in order to perform a continuous circular capsulorrhexis with capsular forceps
  • The lens nucleus is hydrodissected with cold BSS® irrigation using a Binkhorst, or a straight Rycroft cannula, inserted through the corneal incision
  • The process of phacoemulsification is performed with cold fortified BSS® irrigation during linear and pulsed phaco. During phacoemulsification, the cornea must be kept chilled with cold BSS®. When the tip of the phacoemulsifier is inserted into the anterior chamber, the corneal incision is cooled by continuous irrigation from a flask of cold BSS®
  • Cortical aspiration is performed with cold fortified BSS® irrigation
  • Cold Viscoat® is injected into the capsular bag and the corneal incision is extended to 4.1 mm after chilling. Once the corneal incision is cooled with BSS®, a foldable IOL is implanted
  • Closure of the incision is performed by stromal hydration using cold BSS®.
An important point in this technique is the cooling of the incision area before introducing any instrument into the eye.
I have also found it helpful to dim the illumination of the operating microscope initially so that the patient is not startled by the bright light. You can then gradually increase the illumination as needed for visualization intraoperatively. It is also very important that the microscope light is at the lowest intensity level and to tell the patient to fix his gaze at the microscope light. The skill and experience of the surgeon is very important in order to perform this technique.
 
Xylocaine Jelly
This method of topical anesthesia with 2 percent lidocaine hydrochloride gel (AstraÒ) allows cataract surgeons to eliminate the risks associated with needle injection. The gel helps to keep the cornea moistened and increases contact time with the ocular surface, insuring sustained diffusion and prolonged anesthetic effect. On the other hand, the gel is minimally absorbed by the ocular mucous, reducing the risk of secondary systemic effects.
In preparation for surgery, the patient received three doses of 2 percent xylocaine Jelly (two doses in the holding area, and one before the eye was prepped and draped for the procedure).
The administration of 2 percent xylocaine jelly has demonstrated pain scores similar to those with intracameral anesthesia.
This type of topical anesthesia is used by urologists in urological explorations (cystoscopy, catheterization, exploration by sound and other endourethral operations). Other indications are: nasal and pharyngeal cavities in endoscopic procedures such as gastroscopy and bronchoscopy, proctoscopy and restoscopy and tracheal intubation.
 
Viscoanesthesia
This a new type of topical intracameral anesthesia by means of a viscoelastic cohesive material which contains an anaesthetic component.
The topical component used pre-operatively, consists of a mixture of 0.3 percent sodium hyaluronate and 2 percent lidocaine hydrochloride, while the intracameral component used per-operatively consists of 1.5 percent sodium hyaluronate and 1 percent lidocaine hydrochloride commercially known as VisThesiaTM (C IBA Vision Surgical, Switzerland).
The first step of the viscoanesthesia procedure involves the preoperative application of the topical component of VisThesiaTM. Once the topical mixture is applied, the patient's eyes are kept closed for approximately 1 minute to allow for optimum diffusion of the mixture. The VisThesiaTM intracameral component is then used as a normal viscoelastic, mainly before capsulorrhexis and before IOL implantation.13
Preliminary results demonstrate the efficacy and safety of VisThesiaTM concept as a viscoanesthetic method for cataract surgery. It provides a longer anesthetic effect when compared with the application of only an aqueous topical anesthetic.
Researchers have evaluated the VisThesiaTM intracameral component in an in vitro animal study. Histological evaluation of the retinal and uveal tissues showed no differences between the eyes receiving VisThesiaTM injections compared to eyes in the control group receiving balanced salt solution (BSS). There also was no histological evidence of endothelial damage or endothelial cell loss observed.
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