Other Iris and Ciliary Body Disorders Clinical Trial
Official title:
Evaluation of Topical Anesthesia Alone Versus Combined With Intracameral Lidocaine 1% in Patients Undergoing Implantable Collamer Lens (ICL) Procedure
General anesthesia may be non preferable in many patients undergoing Phakic IOL surgery, as
most of the surgeries take 5-10 minutes at maximum.Traditionally, retrobulbar injections
were performed deep into the orbit, but it is now accepted that peribulbar injections using
shorter needles are safer. In the last few years, continuing concern over the rare but
serious complications of sharp needle blocks has led to increasing interest in the use of
sub-Tenon`s blocks utilizing a blunt cannula 1-5.
Even with the use of blunt canulae sub-Tenon`s block, serious problems can still occur,
especially in myopic patients with large axial length. In phakic IOL surgery,topical
anesthesia has been used successfully for years. Topical anesthesia has several advantages
over regional infiltrative techniques, the foremost of which is the abolition of any risk of
inadvertent injury of the globe or orbital contents 6,7,8. It has a high rate of patient
satisfaction, but still there are some patients that experience intraoperative discomfort.
In this study we compared topical anesthesia alone with topical anesthesia plus intracameral
lidocaine 1% in patients undergoing posterior chamber phakic intra ocular lens;Vision
implantable collamer lens ( ICL/toric ICL) surgery.Intracameral anesthesia is a common
adjunct to topical anesthesia in anterior segment surgery9. It probably provides sensory
blockage of the iris and ciliary body and thereby relieves discomfort experienced during IOL
placement. Intracameral lidocaine alone dilates the pupil well 10 and this is believed to be
because of the direct action of lidocaine on the iris, which in turn causes muscle
relaxation.
were enrolled in this study after obtaining approval from the institutional ethical
committee and written patients consent. We estimated our sample size based on a method
described by Lerman. A sample size of 45 will detect a 20% difference between each group;
this will give an alpha value of 0.05 with a power of 80%. With a fall-out rate of
approximately 19%, we decided to increase the number of patients in each group to 51.All
patients were assessed and only those who were deemed suitable for topical and intracameral
lidocaine 1% were included in the study.Very anxious patients were omitted from the study.
We are planning a study of matched sets of patients receiving the experimental and control
treatments with 1 matched control(s) per experimental subject. Prior data indicate that the
probability of a treatment failure among controls is 0.05 and the correlation coefficient
for exposure between matched experimental and control subjects are 0.1. If the true odds
ratio for failure in experimental subjects relative to control subjects is 0.1, we will need
to study 51 experimental subjects with 1 matched control(s) per experimental subject to be
able to reject the null hypothesis that this odds ratio equals 1 with probability (power)
0.7. The Type I error probability associated with this test of this null hypothesis is 0.3.
All the operations were done by one surgeon (SE).Patients were prepared for bilateral
ICL/TICL procedure on the same day.Group I (1 eye) received topical anesthetic drops and
Group 2 (the second eye) received topical anesthesia plus intracameral lidocaine 1% at the
start of sugery through the 3.00 mm corneal incision. Before giving the anesthetics, a
peripheral vein was cannulated and heart rate, oxygen saturation and non-invasive arterial
blood pressure were monitored.Topical anesthesia was done with 2% tetracaine local
anesthetic drops .
Pain was estimated by the patient using a simple pain score: no pain =0; that does not
interfere with the surgical technique, discomfort=1; the surgical technique is performed
with difficulty, pain=2; the surgeon is unable to continue the surgical technique. The
scoring was done during different stages of surgery: lid retraction while inserting a
speculum, tolerance to the microscope light, corneal incision, intraocular lens insertion,
tucking of footplates, irrigation and aspiration (I/A) of viscoelastic, and peripheral
iridectomy. The surgical technique was performed through a clear corneal 3.0 mm tunnel
incision, followed by sodium hyaluronate injection, ICL/toricICL
implantation(V4B,STAAR,California,USA) and unfolding, tucking of trailing footplates then
side port incision and tucking of leading footplates, MIOSTAT 0.01% (Alcon,Texas,USA)
injection, then peripheral iridectomy .
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Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor), Primary Purpose: Treatment