Evaluation of Topical Anesthesia Alone Versus Combined With Intracameral LIdocaine 1%
Condition: Other Iris and Ciliary Body Disorders
Study type: Interventional

Summary: 
      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.
    

Detailed description: 
      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 .
    

Intervention name(s): topical anesthesia; topical anesthesia plus intracameral lidocaine 1%
Intervention type(s): Drug; Drug
Intervention description(s): topical anesthetic drops and Group 2; received topical anesthesia plus intracameral lidocaine 1%
Other intervention name(s): LOCAL ANESTHESIA; received topical anesthesia plus intracameral lidocaine 1%
Intervention MeSH terms: Lidocaine; Anesthetics
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: topical anesthesia; intracameral lidocaine; implantable collamer lens