Sclerotomies (20-gauge) for which diathermy was not applied showed homogeneous collagen architecture throughout the thickness of the sclera (A), large-gauge (20-gauge) sclerotomies for which diathermy was applied demonstrated partial-thickness outer scleral melting and denaturation of scleral collagen (B), and scleral fusion of tissue over the sclerotomies sealing the outer portion of the sclerotomies was noted in all the small-gauge (23-, 25-, and 27-gauge) sclerotomies (C) (hematoxylin-eosin and Masson trichrome collagen stains, original magnification ×20).
Treatment of a leaking sclerotomy using diathermy.
Barak Y, Lee ES, Schaal S. Sealing Effect of External Diathermy on Leaking Sclerotomies After Small-Gauge VitrectomyA Clinicopathological Report. JAMA Ophthalmol. 2014;132(7):891-892. doi:10.1001/jamaophthalmol.2014.341
Small-gauge vitrectomy has surged in popularity in recent years and has become a widespread alternative to traditional techniques. Eighty-five percent of retinal surgeons now routinely use 25- or 23-gauge systems for uncomplicated macular surgery compared with 22% in 2005.1
These small-gauge systems have advantages over larger-gauge systems, including shorter operative times, less tissue manipulation, decreased postoperative inflammation and pain, and quicker visual recovery.2 However, the sclerotomies are not routinely sutured in small-gauge vitrectomy, resulting in a unique set of potential postoperative complications, namely, wound leakage predisposing to postoperative hypotony, incomplete fill of tamponading agents, and possibly an increased risk of postoperative endophthalmitis. Applying external diathermy on a leaking sclerotomy is effective in sealing the surgical wound.3,4
The purpose of this clinicopathological report is to evaluate local histological and wound architecture changes in scleral wounds of varying sizes following the application of external diathermy.
A 3-port pars plana vitrectomy was performed on fresh porcine eyes to remove the vitreous gel. After conjunctival displacement, the sclera was penetrated 3.0 mm from the limbus in a beveled manner, with insertion at a 30° angle, then beveled to a 90° angle, using trocars of various sizes: 20-, 23-, 25-, and 27-gauge trocars. At the end of the surgical procedure, external bipolar diathermy with a power of 44 W was applied to the sclerotomy sites for 5 seconds. These eyes were compared with a nondiathermized control. This experiment was repeated 3 times in 3 different eyes for every gauge tested. Eyes were then placed in 4% formaldehyde and embedded in paraffin.
Histological sections through the sclerotomy sites were stained with hematoxylin-eosin and Masson trichrome collagen stains. Sites were microscopically examined for histological changes, with particular attention to collagen changes sealing the wounds, and for adhesion of conjunctiva to the sclerotomies.
Sixty percent of the small-gauge (27- and 25-gauge) sclerotomies were closed without diathermy, in comparison with none of the larger-gauge sclerotomies.
Histological sections of all sclerotomies for which diathermy was not applied showed sclerotomies with homogeneous collagen architecture throughout the thickness of the sclera (Figure, A). Large-gauge (20-gauge) sclerotomies for which diathermy was applied demonstrated partial-thickness outer scleral melting and denaturation of scleral collagen (Figure, B). Fusion of tissue over the sclerotomies sealing the outer portion of the sclerotomies was noted in all the small-gauge sclerotomies (Figure, C).
Sclerotomy suturing of at least 1 sclerotomy is reported in a mean of 38.5% of cases with 23-gauge vitrectomy surgery (range, 2.2%-93%)3 and in 7.1% of cases with 25-gauge vitrectomy surgery.2 Potential drawbacks of sclerotomy suturing are astigmatism and postoperative inflammation. Applying external diathermy on a leaking sclerotomy was suggested as a useful, easy, and less traumatic technique to reduce the entry of ocular surface fluid into these incisions and prevent leakage of intraocular fluid in the immediate postoperative period, thus potentially reducing the incidence of postoperative endophthalmitis and hypotony.3 However, the mechanism was never demonstrated and was speculated to be conjunctival adhesion over the surgical wound. Porcine sclera was reported to have inferior mechanical stiffness in comparison with human aged sclera. Differences in collagen content and cross-link density may vary with age and with axial length if this experiment were to be performed on human sclera.5 In this article, we demonstrate the mechanism by which external diathermy seals small-gauge sclerotomies.
To our knowledge, this is the first clinicopathological report demonstrating the histological scleral changes composing fusion of scleral collagen to seal the sclerotomy site. We believe this technique to be an easy and effective way to seal leaking sclerotomies in small-gauge sutureless vitrectomy (Video).
Corresponding Author: Shlomit Schaal, MD, PhD, Department of Ophthalmology and Visual Sciences, University of Louisville, 301 E Muhammad Ali Blvd, Louisville, KY 40202 (firstname.lastname@example.org).
Published Online: May 8, 2014. doi:10.1001/jamaophthalmol.2014.341.
Author Contributions: Dr Schaal had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: All authors.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: All authors.
Critical revision of the manuscript for important intellectual content: All authors.
Administrative, technical, or material support: All authors.
Study supervision: Schaal.
Conflict of Interest Disclosures: None reported.
Funding/Support: The work was supported in part by an unrestricted grant from Research to Prevent Blindness, Inc.
Role of the Sponsor: The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.