April 2014
Volume 55, Issue 13
ARVO Annual Meeting Abstract  |   April 2014
Localized RPE removal with a loop instrument in rabbits.
Author Affiliations & Notes
  • Boris V. Stanzel
    Ophthalmology, University of Bonn, Bonn, Germany
  • Fabian Thieltges
    Ophthalmology, University of Bonn, Bonn, Germany
  • Zengping Liu
    Ophthalmology, University of Bonn, Bonn, Germany
    Southwest Eye Hospital, he Third Military Medical University, Chongqing, China
  • Norbert Braun
    Geuder AG, Heidelberg, Germany
  • Warapat Wongsawad
    Ophthalmology, University of Bonn, Bonn, Germany
    Ophthalmology, Wat Raikhing Hospital, Wat Raikhing, Thailand
  • Sudawadee Somboonthanakij
    Ophthalmology, University of Bonn, Bonn, Germany
    Ophthalmology, Wat Raikhing Hospital, Wat Raikhing, Thailand
  • Ralf Brinken
    Ophthalmology, University of Bonn, Bonn, Germany
  • Frank G Holz
    Ophthalmology, University of Bonn, Bonn, Germany
  • Footnotes
    Commercial Relationships Boris Stanzel, Geuder AG (F), Geuder AG (P); Fabian Thieltges, None; Zengping Liu, None; Norbert Braun, Geuder AG (E), Geuder AG (P); Warapat Wongsawad, None; Sudawadee Somboonthanakij, None; Ralf Brinken, Geuder AG (P); Frank Holz, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 1179. doi:
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      Boris V. Stanzel, Fabian Thieltges, Zengping Liu, Norbert Braun, Warapat Wongsawad, Sudawadee Somboonthanakij, Ralf Brinken, Frank G Holz; Localized RPE removal with a loop instrument in rabbits.. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1179.

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      © ARVO (1962-2015); The Authors (2016-present)

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To surgically create a localized RPE wound with minimal trauma to adjacent structures.


Following a 23G core vitrectomy, 2 bleb retinal detachments (bRD) were raised with balanced salt solution (BSS) in 23 eyes of 21 pigmented and 2 albino rabbits. The RPE underneath the bRD was scraped with 3 prototypes of a novel custom-made instrument (Geuder) in a total of 17 eyes, 6 eyes with bRDs alone served as controls. The instrument consisted of an extensible loop folded within a 20G oval nozzle, which could widen and move forward upon release to debride a targeted RPE surface underneath a bRD. The respective loop designs differed in material and thickness (Prolene 0.1 and 0.06mm vs. metal wire 0.1mm). bRD were stabilized with various concentrations of hyaluronic acid (HA, Gelbag®, C. Zeiss Meditec), or BSS alone. All surgical procedures were analyzed by video. The eyes were enucleated following perfusion fixation immediately after the procedure and processed for standard histology. Serial sections were evaluated by lightmicroscopy by two blinded observers seeking for lacerations in BM/ CC and hemorrhages, as well as integrity of the outer retina.


Prolene loops yielded smooth and continuous sliding over the targeted RPE by 3 surgeons, while the metal wire got trapped after some extension. Using 0.1 prolene with a single forward/backward stroke, an area of ca. 2.5x1.5mm was 70% devoid of RPE, yet showed few minuscule BM lacerations and random choriocapillaris blood clots. A single scrape with 0.06 prolene resulted in unsatisfactory RPE denudement, whilst repeated scraping maneuvers caused more BM defects and hemorraghes compared with the 0.1 prolene loop. The metal loop resulted in incomplete RPE removal and intraoperative subretinal hemorraghes. Controls showed normal histology. Injection of ≥ 0.25% HA into bRDs did not result in (collapsing) movements of the overlying retina during RPE scraping, reflected in pilot histologic data with normal outer retinal architecture. Blebs filled with 0.1% HA or BSS alone collapsed upon manipulation, suggesting photoreceptor trauma.


A novel instrument with an extensible 0.1mm prolene loop enabled satisfactory RPE removal, albeit with occasional minuscule BM breaks and CC hemorrhages. This technique may serve as surgical model for geographic atrophy and/ or RPE replacement strategies.

Keywords: 701 retinal pigment epithelium • 741 transplantation • 412 age-related macular degeneration  

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