RESUMEN
AIM: To identify instrument holding archetypes used by experienced surgeons in order to develop a universal language and set of validated techniques that can be utilized in manual small incision cataract surgery (MSICS) curricula. METHODS: Experienced cataract surgeons performed five MSICS steps (scleral incision, scleral tunnel, side port, corneal tunnel, and capsulorhexis) in a wet lab to record surgeon hand positions. Images and videos were taken during each step to identify validated hand position archetypes. RESULTS: For each MSICS step, one or two major archetypes and key modifying variables were observed, including tripod for scleral incision, tripod-thumb bottom for scleral tunnel, underhand-index to thumb grip for side port, index-contact tripod for corneal entry, and tripod-forceps for capsulorhexis. Key differences were noted in thumb placement and number of fingers supporting the instrument, and modifying variables included index finger curvature and amount of flexion. CONCLUSION: Identification of optimal hand positions and development of a formal nomenclature has the potential to help trainees adopt hand positions in an informed manner, influence instrument design, and improve surgical outcomes.
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Sutures are applied almost universally at the site of trauma or surgery, making them an ideal platform to modulate the local, postoperative biological response, and improve surgical outcomes. To date, the only globally marketed drug-eluting sutures are coated with triclosan for antibacterial application in general surgery. Loading drug directly into the suture rather than coating the surface offers the potential to provide drug delivery functionality to microsurgical sutures and achieve sustained drug delivery without increasing suture thickness. However, conventional methods for drug incorporation directly into the suture adversely affect breaking strength. Thus, there are no market offerings for drug-eluting sutures, drug-coated, or otherwise, in ophthalmology, where very thin sutures are required. Sutures themselves help facilitate bacterial infection, and antibiotic eye drops are commonly prescribed to prevent infection after ocular surgeries. An antibiotic-eluting suture may prevent bacterial colonization of sutures and preclude patient compliance issues with eye drops. We report twisting of hundreds of individual drug-loaded, electrospun nanofibers into a single, ultra-thin, multifilament suture capable of meeting both size and strength requirements for microsurgical ocular procedures. Nanofiber-based polycaprolactone sutures demonstrated no loss in strength with loading of 8% levofloxacin, unlike monofilament sutures which lost more than 50% strength. Moreover, nanofiber-based sutures retained strength with loading of a broad range of drugs, provided antibiotic delivery for 30 days in rat eyes, and prevented ocular infection in a rat model of bacterial keratitis.
RESUMEN
PURPOSE: To develop and evaluate an antibiotic-eluting suture for ophthalmic surgery. METHODS: Wet electrospinning was used to manufacture sutures composed of poly(L-lactide), polyethylene glycol (PEG), and levofloxacin. Size, morphology, and mechanical strength were evaluated via scanning electron microscopy and tensile strength, respectively. In vitro drug release was quantified using high performance liquid chromatography. In vitro suture activity against Staphylococcus epidermidis was investigated through bacterial inhibition studies. Biocompatibility was determined via histological analysis of tissue sections surrounding sutures implanted into Sprague-Dawley rat corneas. RESULTS: Sutures manufactured via wet electrospinning were 45.1 ± 7.7 µm in diameter and 0.099 ± 0.007 newtons (N) in breaking strength. The antibiotic release profile demonstrated a burst followed by sustained release for greater than 60 days. Increasing PEG in the polymer formulation, from 1% to 4% by weight, improved drug release without negatively affecting tensile strength. Sutures maintained a bacterial zone of inhibition for at least 1 week in vitro and elicited an in vivo tissue reaction comparable to a nylon suture. CONCLUSIONS: There is a need for local, postoperative delivery of antibiotics following ophthalmic procedures. Wet electrospinning provides a suitable platform for the development of sutures that meet size requirements for ophthalmic surgery and are capable of sustained drug release; however, tensile strength must be improved prior to clinical use. TRANSLATIONAL RELEVANCE: No antibiotic-eluting suture exists for ophthalmic surgery. A biocompatible, high strength suture capable of sustained antibiotic release could prevent ocular infection and preclude compliance issues with topical eye drops.