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Arthur Driscoll, Suzanne LaScalza, Peter Jarrett, Michael McGrath, Michael Bassett, Amar Sawhney; Method Development for Evaluating Clear Corneal Cataract Wound Integrity. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3876.
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© ARVO (1962-2015); The Authors (2016-present)
To develop a quantitative method simulating forces an eye may experience during patient manipulation post-clear corneal cataract surgery.
A Dontrix Gauge (GAC International Inc., Bohemia, NY)(Figure 1a), which is a spring gauge used to apply and measure forces in orthodontics, was modified to have a 3 mm atraumatic tip. The resulting Calibrated Force Gauge (CFG) allows application of calibrated and quantifiable force to the eye in 0.25 ounce increments (Figure 1b). After in-vitro and in-vivo evaluations, an initial clinical study was conducted using the CFG to apply one ounce of force temporal to the limbus in healthy volunteers to examine intraocular pressure (IOP) changes and compare the findings with those in the literature. After confirming the force simulating ocular surface manipulation, the CFG was used to challenge clear corneal incisions (CCIs) which were stromally hydrated (Study 2) or closed with 10-0 Nylon suture (3-1-1 with buried knot)(Study 3); the CFG was placed 0.5 mm temporal to the incision.
In the first study, mean baseline IOP was 17.5 mmHg and rose to 43.4 mmHg upon applying 1.0 ounce of force using the CFG. Literature states that application of light and firm digital forces on the eye equate to IOP of 27 and 58 mmHg respectively. As a result, 1.0 ounce of force appeared adequate to simulate eye touching, rubbing, or forced blinking. When the CFG was used to challenge CCIs closed with stromal hydration in Study 2 (n=30), 66.7% of wounds leaked with ≤ 1.0 ounces of force. In the suture group (Study 3), wounds were challenged prior to and after application of the suture. Only CCIs which leaked on the initial challenge were sutured and challenged with the CFG a second time. Out of these wounds, 23.7% leaked with application of ≤ 1.0 ounces of force (Figure 2).
Applying one ounce of force proximal to a CCI appears to be a clinically relevant assessment of wound integrity and propensity to leak under patient manipulation. Reports in the literature suggest that wounds which leak have a 44-fold increased risk for endophthalmitis. This risk is hypothesized to be related to wound gape allowing fluids to travel between the ocular surface and anterior chamber. If a wound leaks under CFG manipulation after cataract surgery, it may be an indication that the incision architecture is not adequate and closure is necessary to prevent postoperative wound leaks.
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