Modified incision in 25-gauge vitrectomy in the creation of a tunneled airtight sclerotomy: an ultrabiomicroscopic study.

Background: The standard straight incision for 25-gauge vitrectomy may not close well at the end of surgery with post-operative hypotony. To overcome incompetent wound closure, oblique insertion of the trocars has been suggested. More recently we have developed an oblique incision. which is parallel to the scleral fibres instead of perpendicular and therefore avoids cutting. The aim of this study was to compare the effectiveness of the different incisions and to investigate their behaviour with the UBM.

Methods: 45 patients affected by macular holes were operated; in 15 eyes using oblique-parallel insertion (OPAI), in 15 oblique-perpendicular (OPEI) and in 15 straight incision (SI). Patients underwent UBM examinations 1 day, 1 week, 1 month p.o.

Results: OPAI was airtight after the removal of 25 g cannulas. UBM examination 1 day post-operatively (p.o) showed the 45 sclerotomies were well healed with perfect apposition of the internal wound lips. 39 sclerotomies were undetectable, 6 slightly evident. With OPEI the incisions were airtight at the end of surgery. At the 1 day p.o. UBM examination the 45 sclerotomies were well-healed but a minimal gape was clearly visible in all of them, 3 eyes showed peripheral cilio-choroidal (CCD) detachment, which was resolved after 7 days although the gape was still evident. At 1 month p.o. examination the gape was not detectable in 20 sites, evident in 25. With SI at the end of the surgery conjunctival bleb formation was detected in 10 cases, air-gas refilling was performed in 7 eyes and 3 sclerotomies were sutured. At 1 day p.o. hypotony was recorded in 5 patients, recovering at the 7 day follow-up. At the 1 day p.o. UBM examination showed a significant gape in all sites, weak vitreous entrapment was shown in 36, subconjunctival fluid in 4, CCD in 7. At the 7 day UBM the CCD had disappeared in 4 and was reduced in 3. At the 1 month p.o. the sclerotomy defect was still detectable but other complications were no longer evident.

Conclusions: OPAI achieved the quickest and most complete sealing since the 1st day p.o without complications, therefore it could be safer when performing 25-g vitrectomy with extensive manipulation.