Developing transcutaneous nanoenabled anaesthetics for eyelid surgery

Purpose: Local anaesthesia in eyelid surgery carries inherent risks, which has spurned ongoing investigation to identify needleless alternatives. Nanomedicines ( particles ranging between 10 nm and 1000 nm in size) have shown promise in the transcutaneous delivery of certain drugs. In this study, we explore the feasibility of nanoenabled lidocaine delivery across an artificial skin analogue. Materials and methods: Three different lidocaineloaded nanocarriers were characterised. Diffusion studies were performed through cellulose membranes using customised Franz cells. The nanocarriers included polymeric micelles (PMs) (Soluplus), solid lipid nanoparticles (SLNs) (Tripalmitin: Lecithin: Labrasol: polysorbate-20: water; 3.33:1:40:1:4.67 w/w) and selfnanoemulsifying drug delivery systems (SNEDDS) (Capryol-90: Transcutol: Labrasol; 1:3:6 w/w). Particles were characterised in terms of size, zeta-potential and morphology. One-way analysis of variance (ANOVA) with post hoc Tukey's tests were used to assess differences in permeation at a significance of p<0.05. Results: Lidocaine loading was highest in SNEDDs (50 ± 2.1 mg/g) compared with PMs (13.4 ± 0.6 mg/mL) and SLNs (2.8 ± 0.5 mg/mL). All particles possessed a size below 150 nm, illustrated good colloidal stability with a negative zeta-potential and a spherical morphology as demonstrated by transmission electron microscopy images. Cumulative lidocaine concentration after 6 h was significant for both PMs (345.7 ± 23.8 mg/ cm2/h) and SNEDDS (224.8 ± 118.2 mg/cm2/h) compared with SLNs (127.3 ± 25.4 mg/cm2/h). However, SLNs provided controlled release of lidocaine with a linear gradient that continued to increase up to 6 h. Discussion: These results highlight the potential capability of nanoparticle lidocaine delivery in eyelid surgery. The achieved flux for all nanomedicines was higher than that reported for currently approved topical lidocaine formulations (including EMLA cream)

Transcutaneous anaesthetic nano-enabled hydrogels for eyelid surgery

Local anaesthetics are administered as a diffuse superficial slow injection in blepharoplasty. Current transcutaneous local anaesthetic formulations are not licensed for use on the face due to safety concerns. Here we report for the first time the permeation of local anaesthetics (lidocaine, bupivacaine loaded SNEDDS and their hydrogels) across human eyelid and mouse skin as a novel and ocular safe formulation for eyelid surgery. SNEDDS were loaded with high levels of anaesthetics and incorporated within carbomer hydrogels to yield nano-enabled gels. Lidocaine hydrogels have a significantly reduced lag time compared to EMLA, while they enhance lidocaine flux across human eyelid skin by 5.2 fold. Ex vivo tape stripping experiments indicated localisation of anaesthetics within the stratum corneum and dermis. Initial histopathological studies have shown no apparent signs of skin irritation. These results highlight the potential clinical capability of nano-enabled anaesthetic hydrogels as a non-invasive anaesthetic procedure for eyelid surgery

Man versus Machine: Software Training for Surgeons-An Objective Evaluation of Human and Computer-Based Training Tools for Cataract Surgical Performance

This study aimed to address two queries: firstly, the relationship between two cataract surgical feedback tools for training, one human and one software based, and, secondly, evaluating microscope control during phacoemulsification using the software. Videos of surgeons with varying experience were enrolled and independently scored with the validated PhacoTrack motion capture software and the Objective Structured Assessment of Cataract Surgical Skill (OSACCS) human scoring tool. Microscope centration and path length travelled were also evaluated with the PhacoTrack software. Twenty-two videos correlated PhacoTrack motion capture with OSACCS. The PhacoTrack path length, number of movements, and total procedure time were found to have high levels of Spearman&apos;s rank correlation of −0.6792619 ( = 0.001), −0.6652021 ( = 0.002), and −0.771529 ( = 0001), respectively, with OSACCS. Sixty-two videos evaluated microscope camera control. Novice surgeons had their camera off the pupil centre at a far greater mean distance (SD) of 6.9 (3.3) mm, compared with experts of 3.6 (1.6) mm ( ≪ 0.05). The expert surgeons maintained good microscope camera control and limited total pupil path length travelled 2512 (1031) mm compared with novices of 4049 (2709) mm ( ≪ 0.05). Good agreement between human and machine quantified measurements of surgical skill exists. Our results demonstrate that surrogate markers for camera control are predictors of surgical skills