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Helical Loops or Notches at Corners ?. Hexagon or Square Shape ?. The Art & Science of Pupil Dilating Devices. Dr. Suven Bhattacharjee. MS, DO, DNB, FRF. suvenb@gmail.com. Open or Closed Ring ?. Polypropylene or Nylon Material ?.
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Helical Loops orNotchesatCorners? Hexagonor Square Shape? The Art & Science of Pupil Dilating Devices Dr. Suven Bhattacharjee. MS, DO, DNB, FRF. suvenb@gmail.com Open or ClosedRing? Polypropylene orNylon Material? 2.2-2.5 mm or 0.9 mm (20G) Incision? No Financial Interest Patent Pending (PCT) For authors devices Nayan Eye Associates Kolkata. INDIA.
Square or Hexagon ? 6 mm 3.46 mm • For a 5 mm Capsulorhexis, an Incircle of 6 mm is required within the Regular Polygon shaped Pupil Dilating device. (Regular Polygon: All sides & angles equal) • A Square with an Incircle of 6 mm,lies within a 8.48 mm Circumcircle. • A Hexagon with an Incircle of 6 mm,lies within a 6.92 mm Circumcircle. • Smaller Hexagonal device - easier to handle – less injury to Cornea, Iris & Angle. • Smaller Hexagonal device - less stretch & damage to sphincter – Post Op Round pupil. 6.92 mm 8.48 mm
Square or Hexagon ? 3.46 mm 3.46 mm 6 mm 6 mm 6 mm 6 mm • Square with 6 mm side, when deformed : Max length of Diagonal = 6 x 2 = 12 mm. • Hexagon with 3.46 mm side, deformed : Max length of Diagonal = 3.46 x 3 = 10.38 mm. • New device invented by author is available as a Squareand Hexagon. • Square device is longer when deformed and delivered into AC through a small incision. • Square device is also longer when deformed to engage or disengage pupillary margin. • Hexagonal device requires two additional corners to be engaged to Pupillary margin. • But with Notches & Flanges design (nxt slide) – Single flange tuck engages two notches. 6 mm 3.46 mm 12 mm 10.38 mm
Helical Loopsor Notchesat Corners? > 2.2 mm 0.9 mm M Burger • Disadvantagesof Helical loops (Malyugin) at Corners: • Using Top View, aligning the side facing gap to receive pupillary margin – Is Difficult !! • Biplanar structure at Corners - with upper and lower lips - Snags the incision !! • Very small part of the Pupillary margin is engaged – Can Slip out !! • Each Helical loop acts like a torsion & compressionspring when the ring is deformed – • widening or narrowing the gap - Could crush or release the pupil margin unpredictably !! • New design by author, with Notches at corners and Flanges on sides with entire device lying in Single plane, does not snag the incision. Device holds on to the Iris and does not get dislodged easily. • Notches - can straighten and pass through a much smaller 0.9 mm (20G) incision • Flanges- easier to tuck than aligning gaps and pupil margin.Single Flange tuck engages two notches
Polypropylene (PP) or Nylon? • PP & Nylonare both Thermoplastic, i.e. softening when heated and hardening when cooled, but are different in many ways.
Open Ring Closed Ring Device maintains Shape Pupil conforms to shape of device 5-0 Nylon 20 G (0.9 mm) incision • Ends need to be wide apart as they collapse due to constricting force of Pupil • Device with 3 Flanges – collapses & is not practical , Thicker / Stiffer 4-0 Nylon required • Free ends can injure Cornea, Iris, Angle & capsule • May be inserted/ Removed through 23 G incision but 20 G preferable. Closed Square Closed Hexagon Conclusion: Square/Hexagon closed ring, 5-0 nylon device, with notches & flanges, in a single plane - appears to be the best choice presently.
