Randomized double-masked controlled trial comparing pain scores with and without the use of supplementary 2% lidocaine gel in LASIK.

PURPOSE: To compare pain scores with and without supplementary topical 2% lidocaine gel in patients undergoing simultaneous bilateral laser-assisted in situ keratomileusis (LASIK) under topical anesthesia using 0.5% proparacaine eye drops. DESIGN: Randomized double-masked placebo-controlled trial. METHODS: Fifty-one Chinese subjects (102 eyes, with 51 eyes in each arm) were included. One eye was randomly allocated to have supplementary 2% lidocaine gel while the other eye received carbomer gel as control, in addition to topical 0.5% proparacaine. The pain scores for each eye during microkeratome flap creation, during laser ablation, and at 15, 30, and 45 minutes after LASIK were assessed. An overall pain score of the LASIK procedure was also obtained. Primary outcome measures were pain scores during and after LASIK. Secondary outcomes included need for additional topical anesthesia, patient cooperation score, and duration and complications of surgery. RESULTS: In the 2% lidocaine gel-treated group, the pain scores were significantly lower during microkeratome flap creation and laser ablation, and postoperatively at 30 and 45 minutes (P<.05 for all). Patients in the lidocaine gel group required less additional topical anesthesia (P=.0004) and were more cooperative (P=.019) as compared to the carbomer gel group. No surgical or postoperative complications were observed. CONCLUSIONS: The use of supplementary 2% lidocaine gel in LASIK is effective in lowering the pain experienced during and up to 45 minutes after LASIK.

In vitro compatibility study of cephalosporin with intraocular irrigating solutions and intracameral medications.

BACKGROUND: To study the compatibility of cephalosporins with intraocular irrigating solutions and intracameral medications commonly used in cataract surgery. DESIGN: The was an in vitro experiment conducted in the Research Laboratory of the Department of Microbiology, the Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong. SAMPLES: Three cephalosporins--cefazolin, cefuroxime and ceftazidime--were separately diluted and mixed with irrigating solutions and intracameral medications to form 192 samples and 12 control solutions. METHODS: The cephalosporins were dissolved in normal saline and further diluted to the concentration of 1 mg in 0.1 mL with normal saline, Ringer's solution, balanced salt solution and fortified balanced salt solutions. These were mixed with balanced salt solutions or fortified balanced salt solutions, with adrenaline, acetylcholine or carbachol and kept at 37°C for 2 h. The concentrations of free cephalosporins were measured with rapid high-performance liquid chromatography at baseline (0 h) and at 2 h. MAIN OUTCOME MEASURES: Free concentrations of cephalosporins at 2 h were compared with mean baseline (0 h) value. A difference of 3 standard deviations or more was considered statistically significant. RESULTS: At 2 h there was a significant drop in the cefuroxime concentration in preparations in which cefuroxime was diluted with normal saline (P < 0.01). In all preparations, the final concentrations of cephalosporins were higher than the minimal inhibitory concentrations (MIC(90)) for microbials commonly isolated from the external eye. CONCLUSION: Cefazolin, cefuroxime and ceftazidime were compatible with irrigating solutions and intracameral medications commonly used in cataract surgery.

Topical anesthesia-induced keratopathy after laser-assisted subepithelial keratectomy.

A 42-year-old woman had uneventful bilateral laser-assisted subepithelial keratectomy (LASEK) to correct myopia. She experienced intense pain in the first postoperative week and obtained topical oxybuprocaine for pain relief. Subsequently, she developed bilateral persistent corneal epithelial defects, epithelial edema, and bullae that failed to heal with bandage contact lens and topical lubricants. Over the next 4 months, there was progressive corneal stromal thinning and descemetocele formation in 1 eye, requiring application of cyanoacrylate glue, and stromal edema and scarring in the other eye, which resulted in a visual acuity of counting fingers. Investigations did not reveal associated infection or an underlying immunological disorder; however, the patient admitted to excessive use of topical anesthetic eyedrops in the post-LASEK period. She subsequently had penetrating keratoplasty and lens extraction with IOL implantation in the right eye. The left eye healed with central corneal scarring. This case illustrates that serious sight-threatening complications may occur after LASEK due to abuse of topical anesthetic agents.

Randomized clinical trial of the efficacy and safety of tropicamide and phenylephrine in preoperative mydriasis for phacoemulsification.

PURPOSE: To compare the mydriatic effect and safety between different concentrations of tropicamide and phenyle-phrine in preoperative mydriasis for phaco-emulsification. METHODS: Two hundred and seventeen consecutive eyes in the same number of Chinese patients undergoing phaco-emulsification under local or topical anaesthesia in a university-based eye hospital were analyzed. Patients were randomized into two groups by cluster randomization, each group receiving a different preoperative mydriatic regimen. Regimen A consisted of tropicamide 1.0% with phenylephrine 2.5%, and Regimen B consisted of tropicamide 0.5% with phenylephrine 0.5%. The main outcome measures were horizontal pupillary diameter, systolic, diastolic and pulse pressure and pulse rate. RESULTS: The group who received Regimen A attained a mean horizontal pupillary diameter of 7.00 +/- 1.06 mm. Their pupils were significantly larger than those receiving Regimen B (6.61 +/- 1.03 mm, P = 0.007). No untoward cardiovascular effects were noted in either groups. CONCLUSION: Regimen A attained better preoperative mydriasis for phacoemulsification than Regimen B. Both regimens were safe with regard to their cardiovascular effects. The combination of tropicamide 1.0% and phenylephrine 2.5% is recommended as preoperative mydriatic for phacoemulsification in Chinese patients who have darkly pigmented irides.