Javier Benitez-Herreros

Experimental Model to Evaluate Mechanical Closure Resistance of Sutureless Vitrectomy Sclerotomies Using Pig Eyes

PURPOSE The purpose of this study was to report a novel model for comparing mechanical resistance to intraocular pressure (IOP) increases with 23-gauge (23G) and 25G transconjunctival sutureless vitrectomy (TSV) sclerotomies in the immediate postoperative period using an experimental model of a vitrectomized eye. METHODS This was a prospective, experimental, randomized, and observer-masked experimental study in which TSV 23G and 25G oblique sclerotomies, performed in same cadaveric pig eye, were subject to an increase in IOP. Mechanical resistance was determined by the resistance to intraocular fluid leak through the sclerotomy. The simultaneous use of the different sclerotomy diameters in the same eye avoided interindividual scleral resistance differences. RESULTS This animal model allowed comparison of the effect of different sclerotomy diameters (23G and 25G) on incisional mechanical resistance. One hundred twenty eyes were included. In 60.7% of cases, the 23G sclerotomy first allowed intraocular fluid escape (leaked; P = 0.02). When comparing opening pressure values, 23G sclerotomies leaked at significantly lower pressure levels than 25G sclerotomies (P < 0.0001); 53% of the 25G incisions but only 16% of 23G incisions opened at pressure levels greater than 120 mm Hg. CONCLUSIONS Oblique 23G sutureless sclerotomies offer less mechanical resistance to increases in IOP than do 25G sclerotomies. This animal model may become the basis for future studies to evaluate the advantages of using other types of incision or other surgical tools on sclerotomy closure capacity.

Effect of intravitreal ranibizumab on corneal endothelium in age-related macular degeneration.

Purpose: To determine the effect of intravitreal injection of ranibizumab on the corneal endothelium in patients with choroidal neovascularization in age-related macular degeneration. Methods: Observational prospective case series study. Fifty-two eyes of 52 consecutive patients (29 men, 23 women; age range, 61-80 years) were evaluated. All participants received monthly intravitreal injections of (0.05 mL, 0.5 mg) ranibizumab for 3 consecutive months; the follow-up period was 6 months. Central corneal specular microscopy was performed before injection and at 7 days and 6 months after the first intravitreal injection. The endothelial cell density, coefficient of variation of cell size, and percentage of hexagonal cells were analyzed, and the central corneal thickness was measured. Results: There were no significant differences in the endothelial cell densities, coefficient of variation of cell sizes, and percentage of hexagonal cells values before injection and at 7 days and 6 months after the first intravitreal ranibizumab injection (P = 0.987, P = 0.822, and P = 0.918, respectively). There was also no significant difference in central corneal thickness measurements before injection and at 7 days and 6 months after the first intravitreal ranibizumab injection (P = 0.325). Conclusion: Repeated intravitreal injections of 0.5 mg of ranibizumab do not seem to cause substantial changes in the corneal endothelium at 6 months.

Influence of the Interposition of a Nonhollow Probe during Cannula Extraction on Sclerotomy Vitreous Incarceration in Sutureless Vitrectomy

PURPOSE To evaluate the effect of the cannula removal technique on postoperative vitreous incarceration using an experimental model of vitrectomized eye. METHODS In a prospective, experimental, randomized, and observer-masked study, 118 cadaveric pig eyes were vitrectomized through 23-gauge transconjunctival sclerotomies. Once vitrectomy was finished, one of the superior cannulas was extracted with the illumination probe inserted through it, and the other cannula was removed with a cannula plug inserted. Postoperative incisional vitreous entrapment was evaluated by direct visualization. No vitreous incarceration was classified as grade 0 (G0), thin vitreous entrapment was classified as grade 1 (G1), and thick vitreous strands as grade 2 (G2). RESULTS Considering the sclerotomies whose cannulas were extracted with the light probe inside, vitreous incarceration was detected in 93.2% (73.7% G1, 19.5% G2) of the incisions. In turn, vitreous entrapment was observed in 95.8% (43.2% G1, 52.6% G2) of the entry sites whose cannulas were extracted with the plug inserted. Statistical analysis showed significant differences when comparing postvitrectomy vitreous incarceration grades in sclerotomies according to the cannula extraction technique (P < 0.0001). CONCLUSIONS Interposing the light probe through the cannula during its removal reduces vitreous incarceration grade in our experimental model. This simple maneuver may decrease complications related to vitreous entrapment, such as peripheral retinal tears and acute endophthalmitis.

Intraoperative mitomycin C and corneal endothelium after pterygium surgery.

Purpose: To determine the effect of mitomycin C (MMC) on the corneal endothelium after primary pterygium surgery. Methods: This prospective, interventional, nonrandomized, observer-masked study included 46 consecutive patients (51 eyes) with primary pterygium. The bare sclera technique with 1-minute application of 0.02% MMC intraoperatively was used in all cases. The follow-up period was 3 months. Preoperative and postoperative central corneal specular microscopy was performed. The endothelial cell density, coefficient of variation of cell size, and percentage of hexagonal cells were analyzed, and the corneal thickness was measured. Results: The mean endothelial cell densities preoperatively and 3 months postoperatively were 2382.35 ± 342.07 cells per square millimeter (range, 1020-3129) and 2385.02 ± 356.83 cells per square millimeter (range, 1001-3151), respectively (P = 0.96). The mean coefficients of variation of cell size preoperatively and 3 months postoperatively were 34.31 ± 5.62 (range, 22-49) and 35.29 ± 7.50 (range, 22-55), respectively (P = 0.17). The mean percentages of hexagonal cells values preoperatively and 3 months postoperatively were 52.98 ± 7.32 (range, 32-71) and 51.61 ± 8.98 (range, 32-67), respectively (P = 0.48). The mean pachymetry measurements preoperatively and 3 months postoperatively were 506.65 ± 36.87 μm (range, 411-583) and 502.08 ± 41.33 μm (range, 411-593), respectively (P = 0.99). Conclusions: One intraoperative application of 0.02% MMC for 1 minute after primary pterygium surgery does not seem to cause substantial changes in the corneal endothelium at 3 months.

Optical coherence tomography features of sub-internal limiting membrane hemorrhage and temporary premacular cavity following Nd-YAG laser membranotomy in Valsalva retinopathy

(Fig. 1c). Although she received urokinase and hyperbaric oxygen treatment, her right BCVA remains 0.1. A 61-year-old woman developed blurred vision in the right eye after 6 months of treatment with pegylated interferon-α and ribavirin. Ophthalmologic evaluation revealed scattered or fl ame-shaped retinal hemorrhage (Fig. 2). Since she had never undergone ophthalmologic examination, information regarding her previous retinal status was unavailable. Her BCVA was 0.1 (OD), which recovered to 1.2 (OD) after treatment with urokinase and hyperbaric oxygen.

Influence of Incisional Vitreous Incarceration in Sclerotomy Closure Competency After Transconjunctival Sutureless Vitrectomy

PURPOSE To evaluate the influence that vitreous incarceration may exert on the presence of postoperative conjunctival blebs over sclerotomies after transconjunctival sutureless vitrectomy (TSV). Blebs are formed by incisional leakage due to incompetent closure. METHODS Experimental study in which 23-gauge TSV was performed in 146 cadaveric pig eyes. Once the vitrectomy was finished, triamcinolone was injected inside the vitreous cavity for staining residual vitreous, one of the superior cannulas was extracted over the light probe, and the other cannula was removed with the plug inserted. Postoperative conjunctival blebs in superior sclerotomies were assessed by anterior-segment optical coherence tomography (AS-OCT) in a masked fashion; nondetectable blebs were classified as grade 0 (B0), thin bleb (≤half scleral thickness) as grade 1 (B1), and thick bleb (>half scleral thickness) as grade 2 (B2). Postoperative incisional vitreous entrapment was evaluated by slit-lamp photographs in a masked way; no incarceration was classified as grade 0 (V0), thin incarceration as grade 1 (V1), and thick incarceration as grade 2 (V2). RESULTS Conjunctival blebs were found in 13.7% of the sclerotomies (11.3% bleb-B1, 2.4% bleb-B2). Vitreous incarceration was found in 96.5% of the sclerotomies without bleb (B0), 81.8% of the incisions with bleb-B1, and 14.3% of the wounds with bleb-B2. Vitreous incarceration was significantly associated with the absence of conjunctival bleb (P < 0.001). CONCLUSIONS Vitreous incarceration in sclerotomies is related to less incisional leakage in our experimental model. Maneuvers that reduce vitreous entrapment, such as the interposition of a nonhollow probe during the cannula extraction, could decrease the sclerotomy closure competency.

Evaluation of Conjunctival Bleb Detection After Vitrectomy by Ultrasound Biomicroscopy, Optical Coherence Tomography and Direct Visualization

Abstract Purpose: To compare ultrasound biomicroscopy (UBM), anterior-segment optical coherence tomography (AS-OCT), and direct visualization for detecting conjunctival blebs in sutureless sclerotomies after vitrectomy. Conjunctival blebs are formed by sclerotomy leakage due to incompetent closure. Methods: Experimental, randomized, and observer-masked study in which 23-gauge vitrectomies were performed in cadaveric pig eyes. Postoperative conjunctival blebs were assessed by UBM, AS-OCT, and direct visualization. No conjunctival blebs were classified as Grade 0 (G0), thin blebs (less than or equal to one-half of scleral thickness) as Grade 1 (G1) and thick blebs (greater than one-half of scleral thickness) as Grade 2 (G2). Results: Fifty pig eyes were included. Conjunctival blebs were found in 13.3% (8% G1, 5.3% G2) of the incisions analyzed by UBM, in 20% (14.7% G1, 5.3% G2) of the sclerotomies studied by AS-OCT, and in 7.3% (2% G1, 5.3% G2) of the wounds evaluated by direct visualization. AS-OCT was the most sensitive method for identifying conjunctival blebs when compared with UBM and direct visualization (p < 0.001). In turn, UBM was better than direct visualization for observing sclerotomy blebs (p = 0.004). Conclusions: AS-OCT is the most sensitive technique for detecting subclinical blebs (G1) and thus, it may be useful in research for studying the influence that surgical factors and maneuvers may exert on sclerotomy closure capacity after vitrectomy. Direct visualization, that is used in routine clinical practice to determine which sclerotomies should be sutured, is useful only to identify thick blebs (G2) after vitrectomy.

Influence of the Sclerotomy Use on Mechanical Incision Competency in Experimental Model of Vitrectomized Eyes

Purpose: To evaluate the influence of superior sclerotomy use (vitreous cutter or illumination probe entrance) on the postoperative sclerotomy closure competency using an experimental model of vitrectomized eye. Methods: Prospective, experimental, randomized and observer-masked experimental study in which 23 and 25-gauge transconjunctival sutureless vitrectomy was performed through oblique sclerotomies in the same cadaveric pig eye. Closure competency was determined by the resistance to intraocular fluid leak through the superior incisions in face of a progressive intraocular pressure (IOP) rise. Results: 120 eyes included. In 52.5% of cases, the vitreous cutter probe sclerotomy showed intraocular fluid leakage first (p = 0.65). When comparing opening pressure values, there were no significant differences (p = 0.77) between the leakage pressure level of both sclerotomies depending on their use. Conclusions: Different uses of superior sutureless oblique sclerotomies do not seem to influence on TSV incision mechanical resistance to IOP rise in our experimental model.

Endothelial cells analysis after intravitreal ranibizumab (Lucentis) in age-related macular degeneration treatment: a pilot study.

Ranibizumab (rhuFabV2, Lucentis; Genentech, San Francisco, California) is a humanised monoclonal antibody fragment, designed to bind all isoforms of human vascular endothelial growth factor-A (VEGF-A) by preventing the interaction of VEGF-A with its receptors VEGFR-1 (Flt-1) and VEGFR-2 (Flk-1/KDR). Although the pharmacokinetic profile of ranibizumab after intravitreal injection in humans has not been determined definitively, ranibizumab has been detected in the aqueous humour after intravitreal standard injections in a rabbit model.1 Moreover, VEGF and its receptors were expressed in the corneal endothelium.2–5 Therefore, ranibizumab in the aqueous humour after intravitreal injections may affect the function of VEGF in the corneal endothelium, being potentially cytotoxic to human corneal endothelial cells. In the present study, we analyse the effect of the …

Association between macular perfusion and photoreceptor layer status in diabetic macular edema.

Purpose: To evaluate the relationship between the photoreceptor layer status (inner segment ellipsoid band and external limiting membrane) and the foveal avascular zone size, as a result of macular perfusion, in patients with diabetic macular edema. Methods: This observational case series study included 151 eyes of 118 patients with naive diabetic macular edema. The length of the disrupted photoreceptor layer was assessed by optical coherence tomography. The foveal avascular zone diameter was measured on fluorescein angiogram. Results: No significant association was found between the foveal avascular zone size and the mean lengths of the disrupted inner segment ellipsoid band nor the external limiting membrane in patients with naive diabetic macular edema. Conclusion: Macular ischemia, which lengthens the distance from the perifoveal vessels to the center of the fovea and may disrupt the normal flow of nutrients by simple diffusion to the photoreceptor line, does not seem to influence on inner segment ellipsoid band nor external limiting membrane integrity. Future studies may evaluate the effect of choroidal vascularization on the photoreceptor layer status to enhance the knowledge about the photoreceptor layer nutrients source.