Lisette Scheer is an Optometrist and Low Vision Director at Viera VA Outpatient Clinic in Melbourne, Florida. Susannah Marcus- Freeman is an Optometrist at Malcom Randall VA Medical Center in Gainesville, Florida. Correspondence: Lisette Scheer (lisette.scheer@va.gov)
Author disclosures The authors report no actual or potential conflicts of interest with regard to this article.
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Studies have shown that the main incision site is more clinically competent than is the side port incision site, as in our case study.19 Side-port incisions have a 1- or 2-plane architectural profile in contrast to the 3-plane profile typical of a main incision.19 Recent advances including the conversion to clear-corneal incisions of diminishing size, techniques used for wound construction, phacoemulsification machine design, and small-incision IOLs, should further reduce the prevalence and complications of wound compromise.20
Seidel Testing
Seidel testing is the most common method to evaluate corneal wound integrity and identify leaks. A drop of topical anesthetic is instilled in the eye and then a fluorescein strip (not fluorescein sodium and benoxinate hydrochloride ophthalmic solution, which may become less sterile since it has a multiuse container) is applied to the superior conjunctiva. The clinician then looks for evidence of fluid egress using the cobalt blue filter. The patient is instructed to blink once. Fluid egress appears as a black stream as the fluorescein dye becomes diluted by aqueous humor escaping the nonintact wound and the appearance of bright green dye surrounds the leak site. The term Seidel positive indicates a leak. An estimate should be made of the rate and volume of fluid exiting the wound.
Gonioscopy
Gonioscopy can be used to evaluate the postsurgical incision, more specificallyfor identification and management of internal incision wound gape. On gonioscopy, internal wound gape appears as an elongated oval opening resembling a fish mouth. If internal incision wound gape is identified gonioscopicallybefore surgery is complete, the leak can be managed intraoperatively. The surgeon can irrigate along the length of the incision to remove cortical fragments or viscoelastic that may cause internal wound gaping. If unsuccessful, rapidly deepening the anterior chamber with balanced salt solution through the paracentesis incision may be employed. These methods may improve wound stability, reduce risk of postoperative hyphema, lower the incidence of endophthalmitis, andlessen the likelihood of late against-the-rule drift.21
Anterior Segment Optical Coherence Tomography
Instances when Seidel testing was negative despite actual wound gaping have been described.22,23 Anterior segment OCT is useful to evaluate incision architecture. A 2007 United Kingdom study investigated the corneal architecture in the immediate postoperative period following phacoemulsification using anterior segment OCT. This study showed the benefits of identifying architectural features such as epithelial gaping, endothelial gaping, stripping of Descemet membrane, and loss of coaptation. These features were found to be more common at low IOP and could represent a significant risk factor for endophthalmitis.24 Another study published by Behrens and colleagues indicated that a localized detachment of Descemet membrane may be more common than observed with slit-lamp (Figure 7). Corneal gaping, especially if along the entire length of the surgical wound, may lead to inadvertent bacterial access into the anterior chamber.25
Anterior segment OCT imaging was first described by Izatt and colleagues in 1994.26 Unlike posterior segment OCT, anterior segment OCT requires a greater depth of field and higher energy levels as images are commonly distorted by refraction at boundaries where the refractive index changes. Longer infrared wavelengths improve the penetration through tissues that scatter light, such as the sclera and limbus, which allows visualization, for example, of the iridocorneal angle.27,28
Two main scan patterns are used for anterior segment OCT: 512 x 128 cube scan (4-mm width x 4-mm length) and 5-line raster (3-mm length) with adjustable rotation and spacing. A recent software update allows measurement of corneal thickness, visualization of anterior chamber angle structures along with topographic analysis, anterior and posterior elevation maps of the cornea, and reliable pachymetric maps.29,30 The anterior segment cube acquires a series of 128 horizontal scan lines each composed of 512 A-scans. These high-definition scans acquire vertical and horizontal directions composed of 1024 A-scans each. This cube may be used to measure corneal thickness and visualize corneal architecture, creating a 3-D image of the data (Figure 8). The anterior segment 5-line raster scans through 5 parallel lines of equal length to view high-resolution images of the anterior chamber angle and cornea. Each line, fixed at 3-mm in length, is composed of 4096 A-scans.31 Anterior segment cube OCT allows identification of subtle variations in incision architecture at different locations across the width of the OCT image.
