title: Difficulty in inserting 25- and 23-gauge trocar cannula during vitrectomy.
abstract: OBJECTIVE
  To determine the incidence of difficulty in inserting a 25- and 23-gauge trocar cannula (DITC) during 25- or 23-gauge micro-incision vitrectomy surgery (MIVS).
  
  
  METHODS
  Retrospective, consecutive, interventional case series performed by a single surgeon at a single centre. We defined a DITC as the condition where at least 1 trocar cannula could not be inserted into the vitreous at the beginning of MIVS. The incidence of DITC was calculated from 1,525 eyes, and the pre-operative demographics of the DITC cases were compared to those of the non-DITC cases.
  
  
  RESULTS
  The incidence of DITC for all cases was 0.6% (9 of 1,525 eyes). Overall, there were 242 eyes with a retinal detachment (RD), and 8 of the 9 eyes with DITC had an RD with an incidence of 3.3% (8 of 242 RD eyes). Seven of these 8 eyes had a total RD, 4 also had a choroidal detachment, 4 eyes were also myopic (>-8.0 dpt, high myopia), and 6 of the 8 eyes were hypotonic (<8 mm Hg). The DITC cases had larger RDs (p<0.0001), a higher incidence of choroidal detachment (p<0.0001), higher myopia (p=0.0204) and hypotony (p=0.0003) than the non-DITC eyes with an RD.
  
  
  CONCLUSIONS
  A large RD, a choroidal detachment, high myopia and hypotony are significant risk factors for DITC. We recommend that MIVS should be performed cautiously for eyes with these risk factors.
authors: Department of Ophthalmology and Visual Science, Tohoku University Graduate School of Medicine, Sendai, Japan. kunikata@oph.med.tohoku.ac.jp
authors: Hiroshi
authors: H
authors: Kunikata
authors: Fumihiko
authors: F
authors: Nitta
authors: Yasuhiko
authors: Y
authors: Meguro
authors: Naoko
authors: N
authors: Aizawa
authors: Takehiro
authors: T
authors: Hariya
authors: Naoki
authors: N
authors: Chiba
authors: Toshiaki
authors: T
authors: Abe
authors: Kohji
authors: K
authors: Nishida
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002404:Catheterization / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D015862:Choroid Diseases / Q000601:surgery; D005260:Female; D006801:Humans; D007431:Intraoperative Complications; D008297:Male; D008866:Microsurgery / Q000295:instrumentation*; D008875:Middle Aged; D012163:Retinal Detachment / Q000601:surgery*; D012189:Retrospective Studies; D014821:Vitrectomy / Q000295:instrumentation*; D055815:Young Adult