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R. I. Fish; Intraocular Penetration of the Resnick 25 Gauge (2.6 mm) Subretinal Fluid Drainage Needle. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5691. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To determine depth of intraocular penetration of the Resnick (Synergetics Inc., St. Louis, Mo) 25 gauge (2.6mm) transcleral subretinal fluid drainage needle for potential use in transcleral tumor biopsy.
A cadaveric study on 5 human eyes obtained from the Wisconsin Eye Bank as frozen specimens not suitable for transplantation was performed. Axial length of all eyes at 20mm Hg intraocular pressure was measured. The depth of transcleral penetration of the 2.6mm 25 gauge aspirating needle was measured in 24 points encircling the eye at various distances posterior to the limbus (4mm, 8mm, 12mm). Eyes were transected sagitally at the medial limbus to allow measurement of the transcleral needle passage using a sliding microcaliper. Statistical variability for our method of measurement was determined by obtaining random repeat measurements at various locations of previously measured points. Student’s t-test was used to compare measurements taken at 4mm, 8mm, 12mm posterior to the limbus.
Average axial length of the specimens measured 24.44mm (range, 23.5-26). Average transcleral penetration of the needle was measured to be 2.173mm (range 200-1000um, +/- 404um 95% CI). Average transcleral penetration at 4mm, 8mm, and 12mm posterior to the limbus was 575um (range, 300-1000um), 425um (range, 200-800um), and 373um (range, 200-800um), respectively. Student’s t-test calculated p<.01 comparing measurement differences between anterior points (4mm) and posterior points (8mm and 12mm). No difference in depth of penetration according to anatomical meridian of eye could be determined. Variability of the measuring method was determined to be .053mm (+/-.063mm)
The Resnick 25 gauge (2.6mm) subretinal fluid drainage needle penetrates the ocular wall anterior to the equator an average of 2.17mm (range, 200-1000um). A statistically significant difference in depth of penetration was found when comparing anterior points (4mm) with more posterior points (8 and 12mm) (p<.01). No statistical difference was detected when comparing 8mm and 12mm. Depth of penetration does not vary with ocular anatomical meridian. The Resnick 25 gauge needle may be useful for transcleral biopsy of choroidal tumors located anterior to the equator.
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