Implementation of a Novel Near Visual Acuity Chart in an Emergency Department Setting.

PURPOSE: The quality of visual acuity (VA) measurement in emergency department (ED) settings can be affected by patient immobility and lack of standardized testing conditions. We implemented a previously validated, novel VA chart, the Runge Sloan letter near card, in a hospital ED and evaluated its impact on frequency and consistency of VA testing. METHODS: Two hundred seventeen hospital ED ophthalmology consult records from December 1, 2016, to November 15, 2017, were evaluated in an IRB-approved protocol. Frequency of VA measurement and agreement between nonophthalmic ED technicians and ophthalmology physicians-in-training were assessed. RESULTS: Implementation of the Runge card saw missed technician VA evaluations decrease from 36% (43/120) to 21% (20/97) of ophthalmic consults (p = .01), without significant change in agreement of VA measurements. After implementation, the proportion of VA measurements differing between technicians and residents by ≤2 lines was 51%; with pinhole testing, it improved to 64% (p < .05). In patients with good VA of >20/80, pinhole increased agreement from 58% to 73% (p < .05). CONCLUSIONS: Implementation of the Runge card was associated with improved frequency of VA measurement and, when combined with pinhole testing, increased agreement rates. Our findings suggest utility of training in the use of the Runge card in ED settings.

Adjunctive Yield of Wide-Area Transepithelial Sampling for Dysplasia Detection After Advanced Imaging and Random Biopsies in Barrett's Esophagus.

INTRODUCTION: Little is known about the additive yield of wide-area transepithelial sampling with computer-assisted three-dimensional analysis (WATS-3D) after a thorough examination with advanced imaging. The aim was to evaluate the adjunctive yield of WATS-3D after advanced imaging. METHODS: This is an observational cohort study from January 2017 to December 2018 for consecutive patients who underwent an examination that consists of high-definition white light endoscopy (HDWLE), narrow-band imaging (NBI), volumetric laser endomicroscopy (VLE), and Seattle protocol (SP) biopsies (collectively termed HDWLE-NBI-VLE-SP examination). Raised lesions were removed by endoscopic resection. Areas suspicious for dysplasia on NBI and VLE were biopsied. This was followed by random biopsies and WATS-3D brush biopsies. RESULTS: One hundred thirty-eight cases were included in this study. Thirty-five cases (25% of the total) were identified as some degree of dysplasia on the HDWLE-NBI-VLE-SP examination. Adjunctive use of WATS-3D yielded an additional 12 new cases of dysplasia (9 with crypt dysplasia and 3 with low-grade dysplasia [LGD]), for added yield of 34.3% (=12/35, 95% confidence interval 14.6%-62.2%). When restricting the analysis to LGD and higher, 21 dysplastic cases (15% of the total cases) were identified by HDWLE-NBI-VLE-SP, while WATS-3D found 4 additional new cases (3 with LGD and 1 with high-grade dysplasia) for an added yield of 19% (=4/21, 95% confidence interval 0.6%-45.7%). DISCUSSION: The addition of WATS-3D to an already thorough examination with HDWLE-NBI-VLE-SP may increase the yield of dysplasia detection.

Sustained Anti-Vascular Endothelial Growth Factor Activity of Aflibercept (Eylea) After Storage in Polycarbonate Syringes Used for Intravitreal Injection: A Pathway to Safety and Efficiency.

Purpose: Aflibercept (Eylea™, Regeneron) is supplied in single-use glass vials along with 1 cc polycarbonate syringes. We sought to determine if storage of aflibercept for sustained periods within these syringes would result in loss of antivascular endothelial growth factor (anti-VEGF) activity. Methods: Aflibercept samples were drawn from commercially available glass vials into manufacturer-supplied 1-mL syringes and stored at 4°C. Anti-VEGF activity was assessed using enzyme-linked immunosorbent assays at the following storage durations: 0, 4, 9, 14, and 28 days. Frozen samples stored at -20°C for 28 and 56 days were also assayed. Also, a subset of aflibercept samples was stored and then diluted to 1:10 and progressively smaller concentrations and the assays repeated. Aggregation of aflibercept was tested using a dynamic light scattering assay. Results: There were no statistical differences in anti-VEGF activity among aflibercept samples of 1:1 or 1:10 dilution stored at either 4°C or -20°C at any of the storage intervals (P > 0.05). We also observed persistence of robust anti-VEGF activity for up to 14 days when diluted poststorage to 1:16,000, a concentration that would be expected after >7 vitreous half-lives within the eye (estimated at >50 days). No evidence of drug aggregation in specimens stored for 14 days was observed. Conclusions: Our findings support feasibility of prefilling and storage of aflibercept within manufacturer-supplied polycarbonate syringes for as long as 14 days before use under pharmacy-based sterile conditions, facilitating greater safety and efficiency in many clinics delivering anti-VEGF therapy.

An innovative visual acuity chart for urgent and primary care settings: validation of the Runge near vision card.

OBJECTIVE: We evaluated the Runge card, a near-vision eye chart designed for ease of use, by testing agreement in visual acuity results between it and the Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity chart. As a clinical reference point, we compared the Runge card and an electronic Snellen chart with respect to agreement with ETDRS results. METHODS: Participants consisted of adult eye clinic patient volunteers who underwent a protocol refraction, followed by testing with a Runge card, ETDRS chart, and Snellen chart. Mean logMAR visual acuities were calculated for each method. Agreement levels among the tests were assessed for the group overall and for subjects with good (ETDRS logMAR < 0.6; better than 20/80 Snellen equivalent) and poor (logMAR ≥ 0.6) acuity. RESULTS: One hundred and thirty-eight participants completed testing. The mean ( ± standard deviation) logMAR visual acuities (Snellen equivalent) with Runge, ETDRS, and Snellen, respectively, were 0.66 ± 0.50 (20/91, n = 138), 0.59 ± 0.51 (20/78, n = 138), and 0.67 ± 0.62 (20/94, n = 137). Runge testing agreed similarly with ETDRS and Snellen testing, with CCC 0.92 between Runge and ETDRS, and 0.87 between Runge and Snellen (p = 0.14). Runge agreed better with ETDRS than Snellen agreed with ETDRS in participants with poor acuity (CCC = 0.79 vs. 0.63, respectively, p = 0.001) but not in those with good acuity (CCC = 0.70 vs. 0.87, respectively, p = 0.005). CONCLUSION: Visual acuity measurements with the Runge near card agreed with measurements from the ETDRS to approximately the same degree as did the Snellen chart, suggesting potential utility of the Runge near card, particularly given its user-friendly characteristics and ease of use.

PANRETINAL PHOTOCOAGULATION VERSUS RANIBIZUMAB FOR PROLIFERATIVE DIABETIC RETINOPATHY: Comparison of Peripapillary Retinal Nerve Fiber Layer Thickness in a Randomized Clinical Trial.

PURPOSE: Compare changes in retinal nerve fiber layer (RNFL) thickness between eyes assigned to intravitreous ranibizumab or panretinal photocoagulation and assess correlations between changes in RNFL and visual field sensitivity and central subfield thickness. METHODS: Eyes with proliferative diabetic retinopathy were randomly assigned to ranibizumab or panretinal photocoagulation. Baseline and annual follow-up spectral domain optical coherence tomography RNFL imaging, optical coherence tomography macular imaging, and automated static perimetry (Humphrey visual field 60-4 algorithm) were performed. RESULTS: One hundred forty-six eyes from 120 participants were analyzed. At 2 years, for the ranibizumab (N = 74) and panretinal photocoagulation (N = 66) groups, respectively, mean change in average RNFL thickness was -10.9 ± 11.7 µm and -4.3 ± 11.6 µm (difference, -4.9 µm; 95% confidence interval [-7.2 µm to -2.6 µm]; P < 0.001); the correlation between change in RNFL thickness and 60-4 Humphrey visual field mean deviation was -0.27 (P = 0.07) and +0.33 (P = 0.035); the correlation between change in RNFL thickness and central subfield thickness was +0.63 (P < 0.001) and +0.34 (P = 0.005), respectively. CONCLUSION: At 2 years, eyes treated with ranibizumab had greater RNFL thinning than eyes treated with panretinal photocoagulation. Correlations between changes in RNFL thickness, visual field, and central subfield thickness suggest that the decrease in RNFL thickness with ranibizumab is likely due to decreased edema rather than loss of axons.

Assessing photoreceptor structure in patients with traumatic head injury.

OBJECTIVE: Previous work using adaptive optics scanning light ophthalmoscopy (AOSLO) imaging has shown photoreceptor disruption to be a common finding in head and ocular trauma patients. Here an expanded trauma population was examined using a novel imaging technique, split-detector AOSLO, to assess remnant cone structure in areas with significant disruption on confocal AOSLO imaging and to follow photoreceptor changes longitudinally. METHODS AND ANALYSIS: Eight eyes from seven subjects with head and/or ocular trauma underwent imaging with spectral domain optical coherence tomography, confocal AOSLO and split-detector AOSLO to assess foveal and parafoveal photoreceptor structure. RESULTS: Confocal AOSLO imaging revealed hyporeflective foveal regions in two of eight eyes. Split-detector imaging within the hyporeflective confocal areas showed both remnant and absent inner-segment structure. Both of these eyes were imaged longitudinally and showed variation of the photoreceptor mosaic over time. Four other eyes demonstrated subclinical regions of abnormal waveguiding photoreceptors on multimodal AOSLO imagery but were otherwise normal. Two eyes demonstrated normal foveal cone packing without disruption. CONCLUSION: Multimodal imaging can detect subtle photoreceptor abnormalities not necessarily detected by conventional clinical imaging. The addition of split-detector AOSLO revealed the variable condition of inner segments within confocal photoreceptor disruption, confirming the usefulness of dual-modality AOSLO imaging in assessing photoreceptor structure and integrity. Longitudinal imaging demonstrated the dynamic nature of the photoreceptor mosaic after trauma. Multimodal imaging with dual-modality AOSLO improves understanding of visual symptoms and photoreceptor structure changes in patients with head and ocular trauma.

OUTCOMES OF ANTI-VEGF THERAPY IN CHOROIDAL NEOVASCULARIZATION AFTER MACULAR SURGERY.

PURPOSE: To report treatment outcomes of anti-vascular endothelial growth factor (VEGF) therapy in choroidal neovascularization (CNV) presenting after macular surgery. METHODS: Retrospective analysis of 7 eyes of 7 patients, who were diagnosed to have CNV after macular surgery and were treated with anti-vascular endothelial growth factor therapy. Collected data included demographic details; history of present illness; surgical procedure; and clinical examination including visual acuity at presentation and follow-up with imaging and management. Main outcome measures were resolution of CNV activity at the last follow-up. Secondary outcomes included change in visual acuity at final follow-up from baseline, number of injections, treatment free interval, and adverse events. RESULTS: Seven eyes of 7 patients (2 females and 5 males), which underwent macular surgery (4 macular hole repairs and 3 epiretinal membrane (ERM) removal), were included in this study. Two eyes had drusen at the time of surgery; however, five eyes had no preexisting conditions. Mean interval between surgery and CNV development was 21.07 ± 38.55 months (range, 2 months-9 years). All patients had undergone intravitreal anti-vascular endothelial growth factor injections (range, 2-15; mean number: 5.85) with one eye requiring additional photodynamic therapy (PDT) and focal laser. Visual acuity was unchanged with inactive CNV at the last visit in all eyes after anti-vascular endothelial growth factor therapy. The mean follow-up duration after the development of CNV was 35.5 months (range, 6.5 months-8 years). CONCLUSION: Choroidal neovascularization occurring after otherwise successful macular surgery is uncommon with unknown predisposing factors. This entity appears to have poor visual outcome with currently available anti-vascular endothelial growth factor therapy.

Learning curve and competence for volumetric laser endomicroscopy in Barrett's esophagus using cumulative sum analysis.

BACKGROUND AND STUDY AIMS: Little is known about the learning curve for image interpretation in volumetric laser endomicroscopy (VLE) in Barrett's esophagus (BE). The goal of this study was to calculate the learning curve, competence of image interpretation, sensitivity, specificity, and accuracy of VLE among novice users. METHODS: 31 novice users viewed 96 VLE images electronically at three academic institutions after a brief training session. There were 24 images of each histologic type: normal gastric cardia, normal esophageal squamous epithelium, non-neoplastic BE, and neoplastic BE. The users were asked to identify the correct tissue type and level of confidence. The cumulative summation (CUSUM) technique was used to construct a learning curve. RESULTS: 22 (71 %) of the physicians achieved VLE interpretation competency during their 96-slide review. Half of the physicians achieved competency at 65 images (95 % confidence interval [CI] 45 - 85). There was a statistically significant association between confidence in diagnosis and selecting the correct histologic tissue type (P < 0.001). The median accuracy for esophageal squamous epithelium, normal gastric cardia, non-neoplastic BE, and neoplastic BE was 96 % (95 %CI 95 % - 96 %), 95 % (95 %CI 94 % - 96 %), 90 % (95 %CI 88 % - 91 %), 96 % (95 %CI 95 % - 96 %). The overall accuracy was 95 % (95 %CI 93 % - 95 %). CONCLUSION: The majority of novice users achieved competence in image interpretation of VLE for BE, using a pre-selected image set, with a favorable learning curve after a brief training session. An electronic review of VLE images, prior to real-time use of VLE, is encouraged.

Lumen Apposing Metal Stents (LAMSs) for Drainage of Pancreatic and Gallbladder Collections: A Meta-analysis.

BACKGROUND AND AIMS: Endoscopic ultrasound-guided transmural drainage using lumen apposing metal stents (LAMSs) is becoming a popular and promising therapeutic approach for drainage of intra-abdominal fluid collections. There has been an increasing number of studies evaluating LAMS for drainage of pancreatic pseudocysts (PP), walled-off pancreatic necrosis (WOPN), and gallbladder (GB) drainage. The aim of this meta-analysis is to analyze the literature to date regarding the clinical success, technical success, and adverse events of LAMS in treatment of pancreatic fluid collections and GB drainage. METHODS: A comprehensive search of multiple literature databases through November 2016 was performed. Human studies with at least 10 subjects that examined the clinical success, technical success, and adverse events of LAMS in treating PP, WOPN, and GB drainage were included. RESULTS: A total of 993 patients (608-WOPN; 204-PP; 181-GB drainage) underwent drainage from 20 trials. For drainage of WOPN, the pooled technical success was 98.9% [95% confidence interval (CI): 98.2% to 99.7%] and clinical success was 90% (95% CI: 87% to 93%) (τ=0.001). For drainage of PP, the pooled technical success was 97% (95% CI: 95% to 99%) and clinical success was 98% (95% CI: 96% to 100%), (τ=0.001). For GB drainage, the pooled technical success was 95% (95% CI: 91% to 99%) and clinical success was 93% (95% CI: 90% to 97%), (τ=0.001). Total adverse events occurred in 11% of patients with higher complication rates observed in GB drainage. There was no evidence of publication bias in this meta-analysis. CONCLUSIONS: Endoscopic ultrasound-guided transmural drainage using LAMS is becoming a widely accepted therapeutic approach for the treatment of PP, WOPN, and GB drainage with high clinical and technical success rates and acceptable adverse events. Further prospective randomized trials reporting long-term clinical efficacy and cost-effectiveness are needed to validate LAMS as a therapeutic modality for pancreatic and GB collections.

Rectal indomethacin is protective against post-ERCP pancreatitis in high-risk patients but not average-risk patients: a systematic review and meta-analysis.

BACKGROUND AND AIMS: Rectal indomethacin is a popular chemopreventive agent to help prevent post-ERCP pancreatitis (PEP). Previous meta-analyses have shown an overall protective effect for PEP in average-risk and high-risk patients. However, these meta-analyses are limited by a small number of studies. Recently, more trials have been published addressing this issue. The aim is to determine whether rectal indomethacin prevents PEP in average-risk and high-risk groups, after incorporating these new data. METHODS: A comprehensive search of multiple literature databases in April 2016 was performed. Human prospective randomized controlled trials with placebo controls that examined the effect of rectally administered indomethacin on the incidence of PEP were included. RESULTS: A total of 8 trials between 2007 and 2016 (n = 3778) were included. No significant publication bias existed. All studies used similar criteria to detect pancreatitis. Random effects model meta-analysis showed that the rate of PEP was significantly lower using indomethacin compared with placebo (relative risk, 0.43; 95% confidence interval, 0.28-0.65; P < .001) in high-risk patients. There was no significant statistical or clinical heterogeneity. Among average-risk patients, the rate of PEP was similar (non-significant) between the indomethacin and placebo groups (relative risk, 0.74; 95% confidence interval, 0.52-1.07; P = .115). The result of the main outcome remained robust in multiple sensitivity analyses. CONCLUSIONS: Rectal indomethacin given before or after ERCP is protective against PEP in high-risk patients versus placebo; however, it is not protective in average-risk patients versus placebo.

NEOVASCULAR AGE-RELATED MACULAR DEGENERATION WITH ADVANCED VISUAL LOSS TREATED WITH ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR THERAPY: Clinical Outcome and Prognostic Indicators.

PURPOSE: To describe visual outcome and prognostic indicators in neovascular age-related macular degeneration with advanced visual loss at the initiation of anti-vascular endothelial growth factor therapy. METHODS: A retrospective chart review was performed on a consecutive series of 1,410 patients with neovascular age-related macular degeneration treated with anti-vascular endothelial growth factor therapy at the Medical College of Wisconsin. Subjects were included if at the initiation of therapy they had 20/200 or worse visual acuity (VA) with no other visually limiting eye disease and a minimum follow-up of 6 months. The change in VA at 6 months and 12 months was assessed compared with baseline. Visual improvement/worsening was defined as at least ± 0.3 logMAR (equivalent to 15 ETDRS [Early Treatment Diabetic Retinopathy Study] letters) change. Other factors for analysis included number of injections received, drug type, and various clinical and imaging findings. RESULTS: One hundred thirty-one cases met the study criteria, and 97 were followed for 12 months. Baseline VA was 1.38 logMAR (20/480 Snellen equivalent). Mean VA change (logMAR) consisted of an improvement of 0.23 (P < 0.0001) at 6 months and 0.17 (P = 0.003) at 12 months. At 12 months, VA improved in 45% and worsened in 20%. Among subjects with baseline VA worse than 20/400, VA improved in 57% and worsened in 20%. On univariate analysis at either the 6 months or 12 months follow-up, visual improvement was associated with retinal hemorrhage (P = 0.03) and subretinal fluid (P = 0.02), whereas visual worsening was associated with retinal pigment epithelial detachment (P = 0.04) and intraretinal fluid (P = 0.01). With multivariate analysis, visual improvement was predicted by both a larger number of injections received (P = 0.001) and a poorer baseline VA (P = 0.001). Injection medication type did not influence outcome. CONCLUSION: Statistically significant visual improvement was observed in association with anti-vascular endothelial growth factor therapy in patients with severe neovascular age-related macular degeneration, even in patients whose initial VA was worse than that studied in large anti-vascular endothelial growth factor clinical trials. Numerous clinically discernable or potentially modifiable factors may influence outcome in such patients.

CLINICAL EVALUATION OF THE RAPID ACCESS VITREAL INJECTION GUIDE: A Handheld Instrument for Assisting Intravitreal Injections.

PURPOSE: The Rapid Access Vitreal Injection (RAVI) guide combines the function of an eyelid speculum and measuring caliper into a single instrument for assisting intravitreal injections. This study clinically evaluated the RAVI guide with respect to patient acceptance, complication rates, and operative goals. METHODS: A prospective study was performed on 54 patients undergoing intravitreal injections using the RAVI guide (n = 32) or the speculum/caliper (n = 22). Device-related pain was assessed using the Wong-Baker scoring system, scaled from 0 (no pain) to 10 (agonizing pain). RESULTS: Mean device-related pain score did not differ significantly between the 2 groups, with scores of 0.6 and 0.7 for the RAVI guide and speculum groups, respectively. The rate of significant pain (score of ≥2) was twice as high in the speculum group (7 of 22, 32%) compared with the RAVI guide group (5 of 32, 16%), but this difference was not statistically significant (P = 0.19, Fisher's exact test). Operative goals of avoiding needle touch to lashes/lids and guiding needle insertion to the intended site were achieved in all patients. CONCLUSION: The RAVI guide appeared equivalent to the eyelid speculum in achieving operative goals, with similarly low pain scores. It has the potential for facilitating efficient, accurate, and safe intravitreal injections.

Assessing Photoreceptor Structure in Retinitis Pigmentosa and Usher Syndrome.

PURPOSE: The purpose of this study was to examine cone photoreceptor structure in retinitis pigmentosa (RP) and Usher syndrome using confocal and nonconfocal split-detector adaptive optics scanning light ophthalmoscopy (AOSLO). METHODS: Nineteen subjects (11 RP, 8 Usher syndrome) underwent ophthalmic and genetic testing, spectral-domain optical coherence tomography (SD-OCT), and AOSLO imaging. Split-detector images obtained in 11 subjects (7 RP, 4 Usher syndrome) were used to assess remnant cone structure in areas of altered cone reflectivity on confocal AOSLO. RESULTS: Despite normal interdigitation zone and ellipsoid zone appearance on OCT, foveal and parafoveal cone densities derived from confocal AOSLO images were significantly lower in Usher syndrome compared with RP. This was due in large part to an increased prevalence of non-waveguiding cones in the Usher syndrome retina. Although significantly correlated to best-corrected visual acuity and foveal sensitivity, cone density can decrease by nearly 38% before visual acuity becomes abnormal. Aberrantly waveguiding cones were noted within the transition zone of all eyes and corresponded to intact inner segment structures. These remnant cones decreased in density and increased in diameter across the transition zone and disappeared with external limiting membrane collapse. CONCLUSIONS: Foveal cone density can be decreased in RP and Usher syndrome before visible changes on OCT or a decline in visual function. Thus, AOSLO imaging may allow more sensitive monitoring of disease than current methods. However, confocal AOSLO is limited by dependence on cone waveguiding, whereas split-detector AOSLO offers unambiguous and quantifiable visualization of remnant cone inner segment structure. Confocal and split-detector thus offer complementary insights into retinal pathology.

Correlating Photoreceptor Mosaic Structure to Clinical Findings in Stargardt Disease.

PURPOSE: To demonstrate a method for correlating photoreceptor mosaic structure with optical coherence tomography (OCT) and microperimetry findings in patients with Stargardt disease. METHODS: A total of 14 patients with clinically diagnosed Stargardt disease were imaged using confocal and split-detection adaptive optics scanning light ophthalmoscopy. Cone photoreceptors were identified manually in a band along the temporal meridian. Resulting values were compared to a normative database (n = 9) to generate cone density deviation (CDD) maps. Manual measurement of outer nuclear layer plus Henle fiber layer (ONL+HFL) thickness was performed, in addition to determination of the presence of ellipsoid zone (EZ) and interdigitation zone (IZ) bands on OCT. These results, along with microperimetry data, were overlaid with the CDD maps. RESULTS: Wide variation in foveal structure and CDD maps was seen within this small group. Disruption of ONL+HFL and/or IZ band was seen in all patients, with EZ band preservation in regions with low cone density in 38% of locations analyzed. Normality of retinal lamellar structure on OCT corresponded with cone density and visual function at 50/78 locations analyzed. Outer retinal tubulations containing photoreceptor-like structures were observed in 3 patients. CONCLUSIONS: The use of CDD color-coded maps enables direct comparison of cone mosaic local density with other measures of retinal structure and function. Larger normative datasets and improved tools for automation of image alignment are needed. TRANSLATIONAL RELEVANCE: The approach described facilitates comparison of complex multimodal data sets from patients with inherited retinal degeneration, and can be expanded to incorporate other structural imaging or functional testing.

Local Anesthesia With Blunt Sub-Tenon's Cannula Versus Sharp Retrobulbar Needle for Vitreoretinal Surgery: A Retrospective, Comparative Study.

BACKGROUND AND OBJECTIVE: To evaluate the safety and efficacy of a blunt sub-Tenon's cannula for local anesthesia before vitreoretinal surgery compared to a sharp retrobulbar needle. PATIENTS AND METHODS: Retrospective, comparative study of all patients undergoing vitreoretinal surgery at the Medical College of Wisconsin between August 2009 and November 2013. Institutional review board approval was obtained. RESULTS: Of 940 surgeries performed with a sub-Tenon's cannula, 99% (938 of 940) were completed. Of the 771 surgeries performed with a sharp retrobulbar needle, 99% (770 of 771) were completed. Factors associated with use of a sharp retrobulbar needle over sub-Tenon's cannula were presence of prior scleral buckle (P < .01) and inclusion of scleral buckle placement in the procedure (P < .01). No case of globe perforation, severe retrobulbar hemorrhage, or severe conjunctival chemosis was observed in either group. CONCLUSION: Blunt sub-Tenon's cannula appears as effective and safe as a sharp retrobulbar needle for local anesthesia during vitreoretinal surgery. Vitreoretinal surgeons may wish to consider a blunt sub-Tenon's cannula for local surgical anesthesia.