Abstract
Purpose: :
To compare membrane peeling forces created by 20, 23 and 25 gauge intraocular forceps in a simulated surgical setting.
Methods: :
A model epiretinal membrane was created using rubber cement and a cellophane sheet. Rubber cement created a realistic membrane edge to peel. Cellophane was an ideal simulated retina in this setting because, similar to true retina, it was mobile when exposed to tractional forces. Furthermore, if undue force was generated, a hole in cellophane would result similar to a retinotomy. The synthetic membrane and retina were placed on a pressure transducer which measured downward pushing and outward pulling force on the synthetic retina. Brand new disposable Alcon 20, 23 and 25 gauge forceps were utilized. Each membrane was prepared by dripping 3 drops of rubber cement on cellophane and allowing it dry for ten minutes prior to peeling. For each membrane peel, multiple attempts were performed until a flap was successfully created. The transducer measured force in vectors towards (push) and away (pull) from the retina. Maximum pushing and pulling forces were recorded for each attempt. Three membrane flaps were created with each forceps by a single surgeon. ANOVA statistical analysis was performed.
Results: :
The mean pushing and pulling force for 20 gauge membrane peeling was 4.9mN and 5.3mN respectively; for 23 gauge membrane peeling was 6.6mN and 5.8mN respectively and for 25 gauge membrane peeling was 13.9mN and 13.0mN respectively. The mean number of attempts to create a flap with 20, 23 and 25 gauge forceps was 3.7, 2 and 7.3 respectively. ANOVA analysis found statistically significant differences in pushing force between 20 and 25 gauge (p=0.0002) and 23 and 25 gauge (p=0.0182) membrane peeling. There were statistically significant differences in pulling force between 20 and 25 gauge (p=0.0001) and 23 and 25 gauge (p=0.0019) membrane peeling. There was no significant difference in pushing or pulling force between 20 and 23 gauge membrane peeling (p=0.278 and p=0.646) respectively.
Conclusions: :
In a simulated surgical setting, epiretinal membrane peeling with 25 gauge forceps was found to be more traumatic to the retina with respect to both pushing and pulling forces generated compared with 20 and 23 gauge forceps.
Keywords: macula/fovea • retina