Baseline Sex Differences in Pulmonary Arterial Hypertension Randomized Clinical Trials.

Rationale: Sex-based differences in pulmonary arterial hypertension (PAH) are known, but the contribution to disease measures is understudied. Objectives: We examined whether sex was associated with baseline 6-minute-walk distance (6MWD), hemodynamics, and functional class. Methods: We conducted a secondary analysis of participant-level data from randomized clinical trials of investigational PAH therapies conducted between 1998 and 2014 and provided by the U.S. Food and Drug Administration. Outcomes were modeled as a function of an interaction between sex and age or sex and body mass index (BMI), respectively, with generalized mixed modeling. Results: We included a total of 6,633 participants from 18 randomized clinical trials. A total of 5,197 (78%) were female, with a mean age of 49.1 years and a mean BMI of 27.0 kg/m2. Among 1,436 males, the mean age was 49.7 years, and the mean BMI was 26.4 kg/m2. The most common etiology of PAH was idiopathic. Females had shorter 6MWD. For every 1 kg/m2 increase in BMI for females, 6MWD decreased 2.3 (1.6-3.0) meters (P < 0.001), whereas 6MWD did not significantly change with BMI in males (0.31 m [-0.30 to 0.92]; P = 0.32). Females had lower right atrial pressure (RAP) and mean pulmonary artery pressure, and higher cardiac index than males (all P < 0.03). Age significantly modified the sex by RAP and mean pulmonary artery pressure relationships. For every 10-year increase in age, RAP was lower in males (0.5 mm Hg [0.3-0.7]; P < 0.001), but not in females (0.13 [-0.03 to 0.28]; P = 0.10). There was a significant decrease in pulmonary vascular resistance (PVR) with increasing age regardless of sex (P < 0.001). For every 1 kg/m2 increase in BMI, there was a 3% decrease in PVR for males (P < 0.001), compared with a 2% decrease in PVR in females (P < 0.001). Conclusions: Sexual dimorphism in subjects enrolled in clinical trials extends to 6MWD and hemodynamics; these relationships are modified by age and BMI. Sex, age, and body size should be considered in the evaluation and interpretation of surrogate outcomes in PAH.

BMI and Treatment Response in Patients With Pulmonary Arterial Hypertension: A Meta-analysis.

BACKGROUND: Obesity is increasingly prevalent in pulmonary arterial hypertension (PAH) but is associated with improved survival, creating an "obesity paradox" in PAH. It is unknown if the improved outcomes could be attributable to obese patients deriving a greater benefit from PAH therapies. RESEARCH QUESTION: Does BMI modify treatment effectiveness in PAH? STUDY DESIGN AND METHODS: Using individual participant data, a meta-analysis was conducted of phase III, randomized, placebo-controlled trials of treatments for PAH submitted for approval to the U.S. Food and Drug Administration from 2000 to 2015. Primary outcomes were change in 6-min walk distance (6MWD) and World Health Organization (WHO) functional class. RESULTS: A total of 5,440 participants from 17 trials were included. Patients with overweight and obesity had lower baseline 6MWD and were more likely to be WHO functional class III or IV. Treatment was associated with a 27.01-m increase in 6MWD (95% CI, 21.58-32.45; P < .001) and lower odds of worse WHO functional class (OR, 0.58; 95% CI, 0.48-0.70; P < .001). For every 1 kg/m2 increase in BMI, 6MWD was reduced by 0.66 m (P = .07); there was no significant effect modification of treatment response in 6MWD according to BMI (P for interaction = .34). Higher BMI was not associated with odds of WHO functional class at end of follow-up; however, higher BMI attenuated the treatment response such that every 1 kg/m2 increase in BMI increased odds of worse WHO functional class by 3% (OR, 1.03; P for interaction = .06). INTERPRETATION: Patients with overweight and obesity had lower baseline 6MWD and worse WHO functional class than patients with normal weight with PAH. Higher BMI did not modify the treatment response for change in 6MWD, but it attenuated the treatment response for WHO functional class. PAH trials should include participants representative of all weight groups to allow for assessment of treatment heterogeneity and mechanisms.

Association of Pericardial Fat with Cardiac Structure, Function, and Mechanics: The Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: Pericardial fat has been associated with adverse cardiovascular outcomes through adiposity-associated inflammation and insulin resistance, which in turn are linked to cardiac dysfunction. We sought to evaluate the association between pericardial fat volume and cardiac structure and function in adults without baseline cardiovascular disease. METHODS: We analyzed data from the Multi-Ethnic Study of Atherosclerosis. Linear regression was used to examine the association between pericardial fat volume (by cardiac computed tomography during exam 1, 2000-2002) and cardiac function by echocardiography, six-minute walk distance (6MWD), and symptom severity as assessed using the Kansas City Cardiomyopathy Questionnaire-12 (exam 6, 2016-18). RESULTS: Among 3,032 participants, each 1 SD (39.3 cm3) increase in pericardial fat volume was associated with lower (worse) absolute left atrial reservoir strain (ß = -0.98%; 95% CI, -1.29, -0.68; P < .001), right ventricular free wall strain (ß = -0.75%; 95% CI, -1.00, -0.51; P < .001), and right atrial reservoir strain (ß = -0.59%; 95% CI, -1.00, -0.19; P < .01) after adjustment for potential confounders. Greater pericardial fat volume was associated with lower 6MWDs (ß = -5.70 m; 95% CI, -10.34, -1.06; P = .02) but not with Kansas City Cardiomyopathy Questionnaire-12 scores or N-terminal pro b-type natriuretic peptide after multivariable adjustment. CONCLUSIONS: In a population-based cohort of adults, pericardial fat volume was independently associated with subclinical atrial and right ventricular dysfunction and reduced 6MWD. These distinct changes in cardiac structure and function suggest a potential mechanistic role for pericardial fat in early heart failure.

Insulin Resistance Is Associated with Right Ventricular Dysfunction.

Rationale: The effect of insulin resistance on left ventricular function is well documented; however, less is known regarding its effect on the right ventricle (RV). Objectives: To evaluate the association between insulin resistance and RV function by echocardiography in a cohort of adults without baseline cardiovascular disease. Methods: We performed a retrospective cohort study in the MESA (Multi-Ethnic Study of Atherosclerosis). Linear regression was used to examine the association between overall insulin resistance measured by the mean triglyceride (TG) to high-density lipoprotein (HDL) cholesterol ratio (TG:HDL) and change in TG:HDL over time for each participant with echocardiographic RV function. Logistic regression was used to calculate the odds ratios (ORs) of RV systolic and diastolic dysfunction. Results: Among 3,032 participants, higher mean TG:HDL was associated with lower (worse) absolute RV longitudinal strain (ß, -0.38; 95% confidence interval [CI], -0.64 to -0.13; P < 0.01), tricuspid annular plane systolic excursion (ß, -0.05; 95% CI, -0.07 to -0.04; P < 0.001), and higher odds of abnormal RV strain (OR, 1.26; 95% CI, 1.08 to 1.47; P < 0.01) and abnormal tricuspid annular plane systolic excursion (OR, 1.31; 95% CI, 1.14 to 1.51; P < 0.001). TG:HDL was also associated with lower ratio of tricuspid early to late ventricular filling velocities (E/A) (ß, -0.03; 95% CI, -0.04 to -0.01; P < 0.01), higher ratio of early diastolic tricuspid inflow to tricuspid lateral annular velocity (E/e') (ß, 0.15; 95% CI, 0.07 to 0.23; P < 0.001), and higher odds of graded RV diastolic dysfunction (OR, 1.19; 95% CI, 1.03 to 1.39; P < 0.05). These associations remained following multivariable adjustment. Conclusions: Insulin resistance was associated with decreased RV systolic and diastolic function after adjusting for alternative causes of RV dysfunction, suggesting that insulin-resistant individuals are at risk for early RV dysfunction, even in the absence of cardiovascular disease.

Secular and Regional Trends among Pulmonary Arterial Hypertension Clinical Trial Participants.

Rationale: The population of patients with pulmonary arterial hypertension (PAH) has evolved over time from predominantly young White women to an older, more racially diverse and obese population. Whether these changes are reflected in clinical trials is not known. Objectives: To determine secular and regional trends among PAH trial participants. Methods: We performed a pooled cohort analysis using harmonized data from phase III clinical trials of PAH therapies submitted to the U.S. Food and Drug Administration. We used mixed-effects linear and logistic regression to assess regional differences in participant age, sex, body habitus, and hemodynamics over time. Results: A total of 6,599 participants were enrolled in 18 trials between 1998 and 2013; 78% were female. The mean age of participants in North America, Europe, and Latin America at the time of study start increased by 2.09 (95% confidence interval [CI], 0.67-3.51), 1.62 (95% CI, 0.24-3.00), and 4.75 (95% CI, 2.29-7.21) years per 5 years, respectively (P = 0.01). Body mass index at the time of study start increased by 0.72 kg/m2 per 5 years (95% CI, 0.44-0.99; P < 0.001) across all regions. Eighty-five percent of participants in early studies were non-Hispanic White, but this decreased over time to 70%. Ninety-seven percent of Asians and 74% of Hispanics in the sample were recruited from Asia and Latin America. Conclusions: Patients enrolled in more recent PAH therapy trials are older and more obese, mirroring the changing epidemiology of observational cohorts. However, these trends varied by geographic region. PAH cohorts remain predominantly female, presenting challenges for generalizability to male patients. Although the proportion of non-White participants increased over time, this was primarily through recruitment in Asia and Latin America.

Impact of COVID-19 on inpatient clinical emergencies: A single-center experience.

AIM: Determine changes in rapid response team (RRT) activations and describe institutional adaptations made during a surge in hospitalizations for coronavirus disease 2019 (COVID-19). METHODS: Using prospectively collected data, we compared characteristics of RRT calls at our academic hospital from March 7 through May 31, 2020 (COVID-19 era) versus those from January 1 through March 6, 2020 (pre-COVID-19 era). We used negative binomial regression to test differences in RRT activation rates normalized to floor (non-ICU) inpatient census between pre-COVID-19 and COVID-19 eras, including the sub-era of rapid COVID-19 census surge and plateau (March 28 through May 2, 2020). RESULTS: RRT activations for respiratory distress rose substantially during the rapid COVID-19 surge and plateau (2.38 (95% CI 1.39-3.36) activations per 1000 floor patient-days v. 1.27 (0.82-1.71) during the pre-COVID-19 era; p = 0.02); all-cause RRT rates were not significantly different (5.40 (95% CI 3.94-6.85) v. 4.83 (3.86-5.80) activations per 1000 floor patient-days, respectively; p = 0.52). Throughout the COVID-19 era, respiratory distress accounted for a higher percentage of RRT activations in COVID-19 versus non-COVID-19 patients (57% vs. 28%, respectively; p = 0.001). During the surge, we adapted RRT guidelines to reduce in-room personnel and standardize personal protective equipment based on COVID-19 status and risk to providers, created decision-support pathways for respiratory emergencies that accounted for COVID-19 status uncertainty, and expanded critical care consultative support to floor teams. CONCLUSION: Increased frequency and complexity of RRT activations for respiratory distress during the COVID-19 surge prompted the creation of clinical tools and strategies that could be applied to other hospitals.

Obesity in Pulmonary Arterial Hypertension (PAH): The Pulmonary Hypertension Association Registry (PHAR).

RATIONALE: Obesity is associated with pulmonary arterial hypertension (PAH), but its impact on outcomes such as health-related quality of life (HRQoL), hospitalizations and survival is not well understood. OBJECTIVES: To assess the effect of obesity on health-related quality of life (HRQoL), hospitalizations and survival in patients with PAH. METHODS: We performed a cohort study of adults with PAH from the Pulmonary Hypertension Association Registry, a prospective multicenter registry. Multivariate linear mixed effects regression was used to examine the relationship between weight categories and HRQoL using the Short Form-12 (SF-12) and emPHasis-10 (e10). We used multivariable negative binomial regression to estimate hospitalization incidence rate ratios (IRRs) and Cox regression to estimate hazard ratios (HRs) for transplant-free survival by weight status. RESULTS: 767 subjects were included: mean age of 57 years, 74% female, 33% overweight and 40% obese, with median follow-up duration of 527 days. Overweight and obese patients had higher baseline e10 scores (worse HRQoL), which persisted over time (p<0.001). The overweight and obese have a trend towards increased incidence of hospitalizations compared to normal weight (IRR 1.34, 95% confidence interval (95%CI) 0.94-1.92 and 1.33, 95%CI 0.93-1.89, respectively). Overweight and obese patients had lower risk of transplant or death as compared to normal weight patients (HR 0.45, 95%CI 0.25-0.80 and 0.39, 95%CI 0.22-0.70, respectively). CONCLUSIONS: In a large multicenter, prospective cohort of PAH, overweight and obese patients had worse disease-specific HRQoL despite better transplant-free survival compared to normal weight patients. Future interventions should address the specific needs of these patients.

Obesity Is Associated With Pulmonary Hypertension and Modifies Outcomes.

Background Experimental studies support a link between obesity and pulmonary hypertension (PH), yet clinical studies have been limited. This study sought to determine the association of obesity and pulmonary hemodynamic measures and mortality in PH. Methods and Results We examined patients undergoing right-sided heart catherization (2005-2016) in a hospital-based cohort. Multivariable regression models tested associations of body mass index and pulmonary vascular hemodynamics, with PH defined as mean pulmonary artery pressure >20 mm Hg, and further subclassified into precapillary, postcapillary, and mixed PH. Multivariable Cox models were used to examine the effect of PH and obesity on mortality. Among 8940 patients (mean age, 62 years; 40% women), 52% of nonobese and 69% of obese individuals had evidence of PH. Higher body mass index was independently associated with greater odds of overall PH (odds ratio, 1.34; 95% CI, 1.29-1.40; P<0.001 per 5-unit increase in body mass index) as well as each PH subtype (P<0.001 for all). Patients with PH had greater risk of mortality compared with individuals without PH regardless of subgroup (P<0.001 for all). We found that obesity was associated with 23% lower hazard of mortality among patients with PH (hazard ratio, 0.77; 95% CI, 0.69-0.85; P<0.001). The effect of obesity was greatest among those with precapillary PH (hazard ratio, 0.57; 95% CI, 0.46-0.70; P<0.001), where obesity modified the effect of PH on mortality (P for interaction=0.02). Conclusions Obesity is independently associated with PH. PH is associated with greater mortality; this is modified by obesity such that obese patients with precapillary PH have lower mortality compared with nonobese counterparts. Further studies are needed to elucidate mechanisms underlying obesity-related PH.

Modulating Ocular Scarring in Glaucoma Filtration Surgery Using the Epigenetic Adjunct Suberoylanilide Hydroxamic Acid.

AIM: The aim of this study is to assess the effectiveness of suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor (HDI) with a broad spectrum epigenetic activity, in improving filtration bleb survival as an adjunct therapy to glaucoma filtration surgery (GFS) in the rabbit model. MATERIALS AND METHODS: Eighteen New Zealand White rabbits underwent GFS in the left eye and were randomized to receive either a subconjunctival (SC) injection of 0.1 mL SAHA (9.25 µg/mL) or balanced saline solution (BSS) at the end of surgery, or a 3-minute intraoperative topical application of 0.4 mg/mL mitomycin-C (MMC). Bleb survival and histology were compared. RESULTS: Blebs of rabbits receiving injections of SAHA survived an average (mean ± SD) of 23.2 ± 2.7 days. SAHA rabbits showed a nonsignificant improvement over rabbits that received an injection of BSS, which had a mean survival time of 19.7 ± 2.7 days (p = 0.38) according to a one-way analysis of variance (ANOVA). Eyes receiving intraoperative topical MMC survived an average of 32.5 ± 3.3 days, which is significantly longer than both the control group treated with BSS (p = 0.01) and the experimental group treated with the SAHA (p = 0.0495). SAHA was well tolerated and showed no significant avascularity, necrosis, or conjunctival thinning. CONCLUSION: Although it was well tolerated, a single intraoperative injection of SAHA did not significantly prolong bleb survival in the rabbit model. CLINICAL SIGNIFICANCE: Epigenetic adjuncts hold promise for improving GFS outcome; however, future studies must continue to examine different administration protocols and dosages to substantiate their efficacy. HOW TO CITE THIS ARTICLE: Rodgers CD, Lukowski ZL, et al. Modulating Ocular Scarring in Glaucoma Filtration Surgery Using the Epigenetic Adjunct Suberoylanilide Hydroxamic Acid. J Curr Glaucoma Pract 2019;13(1):37-41.

Sequential Therapy with Saratin, Bevacizumab and Ilomastat to Prolong Bleb Function following Glaucoma Filtration Surgery in a Rabbit Model.

To determine if sequential treatment with Bevacizumab (Avastin), a monoclonal, VEGF antibody that blocks angiogenesis; Saratin, a 12 kD polypeptide with anti-inflammatory and anti-thrombotic properties; and Ilomastat, a matrix metalloproteinase (MMP) inhibitor, prolongs bleb life following glaucoma filtration surgery (GFS) in a rabbit model. Thirty-two New Zealand White rabbits (eight rabbits per group) underwent GFS in the left eye. Group 1 received a perioperative injection of both Saratin and Bevacizumab, and later, subconjuctival injections of Ilomastat on days 8 and 15. Group 2 received only Saratin perioperatively, and also received Ilomastat injections on days 8 and 15. Group 3, the negative control, received a single perioperative injection of Balanced Saline Solution (BSS) along with post-operative BSS injections on days 8 and 15. Group 4, the positive control, received topical treatment with Mitomycin-C (MMC) at the time of surgery with no further treatment. Blebs were evaluated by an observer masked to treatment every third day. Histology was obtained on two eyes in each group on post-op day twelve as well as all eyes following bleb failure. Eyes in group 1 had a mean bleb survival time of 29 ± 2.7 days, whereas those in group 2 that received the experimental treatment without Bevacizumab had a mean survival time of 25.5 ± 2.7 days. An ANOVA test showed that the Saratin/Ilomastat/Bevacizumab group demonstrated a significant prolongation of bleb survival compared to the BSS control-mean survival time of 19.7 ±2.7 days-(p = 0.0252) and was not significantly different from the MMC positive control group (p = 0.4238)-mean survival time of 32.5 ± 3.3. From tissue histology at day 12, the four different groups showed marked differences in the cellularity and capsule fibrosis. The MMC eyes showed minimal cellularity, were avascular and had minimal fibrous tissue. BSS group showed high cellularity, moderate to high fibrosis, and thicker and more defined capsules than either of the treatment groups and the positive control. Both the Saratin/Ilomastat/Bevacizumab and Saratin/Ilomastat only eyes showed moderate cellularity with minimal fibrosis, with less cellularity and fibrosis present in the triple treatment group. Sequential therapy with multiple agents, including Bevacizumab, prolonged bleb function following GFS in the rabbit model and were significantly better than the negative BSS control. The experimental group did not show the same surface tissue histological thinning and side effects associated with MMC treatment.

Prevention of ocular scarring after glaucoma filtering surgery using the monoclonal antibody LT1009 (Sonepcizumab) in a rabbit model.

PURPOSE: Excessive scarring leading to failure of the filtering bleb continues to be a major problem after glaucoma filtration surgery. This study examines the antifibrotic effects of the anti-S1P monoclonal antibody LT1009 (Sonepcizumab) in prolonging bleb survival in a rabbit model of glaucoma filtering surgery. METHODS: The frequency of LT1009 dosage was determined initially using an enzyme-linked immunosorbent assay assay measuring LT1009 eye tissue retention in 6 New Zealand White rabbits. A further 21 New Zealand White rabbits underwent glaucoma filtering surgery. Bleb tissues were observed and compared clinically and histologically. The duration of bleb elevation was compared among LT1009, balanced saline solution (BSS) negative control, and mitomycin-C (MMC)-positive control. RESULTS: The mean duration of bleb survival was 28.5±8.5 days for rabbits receiving injections of LT1009, 21.0±5.6 days for those receiving injections of BSS, and 33.8±5.6 days for rabbits receiving MMC. Analysis of variance with post hoc testing suggests a statistically significant trend of improvement in bleb duration for LT1009 when compared with BSS controls. Nonpainful, upper eyelid edema was noted after 5 injections of LT1009, which resolved over a 10-day period. MMC eyes developed avascular conjunctivas with areas of thinning and sparse cellularity, whereas the conjunctiva of LT1009 and BSS eyes remained relatively normal. CONCLUSIONS: The monoclonal antibody LT1009 demonstrated a longer duration of bleb elevation than BSS control without adverse conjunctival effects associated with MMC. However, after multiple doses LT1009 use was associated with short-term upper eyelid edema.

Comparison of single versus multiple injections of the protein saratin for prolonging bleb survival in a rabbit model.

PURPOSE: We compared the anti-fibrotic effects of single versus multiple postoperative injections of saratin following glaucoma filtration surgery (GFS) in the rabbit model. METHODS: The experiment was in two parts. To determine the optimal frequency for postoperative therapy, seven New Zealand White (NZW) rabbits received an injection of saratin under the superior conjunctiva bilaterally, and ocular tissue concentration was determined using Western blot and bicinchoninic acid (BCA) assay. Next, 32 additional NZW rabbits underwent filtration surgery and received either single or multiple-dose saratin treatments. Mitomycin-C (MMC) and balanced saline solution (BSS) treatment acted as positive and negative controls, respectively. RESULTS: Rabbits receiving only one perioperative saratin injection had a mean bleb survival time of 29.8 ± 5.3 days, while those receiving multiple (either 3 or 5+) injections of saratin had mean bleb survival times of 26.3 ± 8.1 and 26.4 ± 4.2 days, respectively. Analysis of variance with post-hoc testing showed the single injection group had a statistically favorable effect on bleb survival duration compared to BSS controls and was not significantly different from MMC. The conjunctivas of the saratin-treated rabbits did not show the thinning or avascularity that was seen in the MMC treatment group. Rabbits receiving more than three injections of saratin suffered temporary conjunctival redness and two rabbits had upper eyelid edema. CONCLUSIONS: A single postoperative injection of saratin was able to prolong the duration of bleb elevation when compared to BSS controls. Additional treatments of saratin seemed to reduce effectiveness and caused short-term eye inflammation.

Prevention of ocular scarring post glaucoma filtration surgery using the inflammatory cell and platelet binding modulator saratin in a rabbit model.

CLINICAL RELEVANCE: Late complications can occur with use of current antimetabolites to prevent scarring following glaucoma filtration surgery (GFS). Safer, more targeted, anti-fibrosis agents are sought. OBJECTIVES: The protein saratin has been shown to exhibit anti-fibrotic and anti-thrombotic properties in response to injury, but had not been used for glaucoma surgery. The goal of this study was to compare the efficacy of saratin with that of the widely accepted mitomycin-C (MMC) in prolonging bleb survival following GFS in the rabbit model. Two saratin delivery routes were compared; a single intraoperative topical application versus a combination of intraoperative topical application with two additional postoperative injections. METHODS: Twenty-four New Zealand White rabbits underwent GFS and received either intraoperative topical saratin, intraoperative topical saratin plus two injections on post-operative days 4 and 8, balanced saline solution (BSS), or MMC. The bleb tissues and their elevation durations were compared based on clinical and histological findings. RESULTS: Rabbits receiving topical+injections of saratin had a mean bleb survival of 33.6±8.5 days, significantly higher than the negative BSS controls, which averaged 17.4±6.0 days (p = 0.018). No improvement over BSS was seen for rabbits receiving topical saratin only (15.5±4.8 days, p = 0.749). Rabbits receiving saratin did not develop bleb avascularity and thinning associated with MMC treatment and there were no apparent clinical signs of toxicity. CONCLUSIONS: Treatment with a single intraoperative topical application plus two additional postoperative injections significantly prolonged bleb elevation comparable to MMC, but without toxicity; however, topical application alone was ineffective.

Ab-externo AAV-mediated gene delivery to the suprachoroidal space using a 250 micron flexible microcatheter.

BACKGROUND: The current method of delivering gene replacement to the posterior segment of the eye involves a three-port pars plana vitrectomy followed by injection of the agent through a 37-gauge cannula, which is potentially wrought with retinal complications. In this paper we investigate the safety and efficacy of delivering adeno-associated viral (AAV) vector to the suprachoroidal space using an ab externo approach that utilizes an illuminated microcatheter. METHODS: 6 New Zealand White rabbits and 2 Dutch Belted rabbits were used to evaluate the ab externo delivery method. sc-AAV5-smCBA-hGFP vector was delivered into the suprachoroidal space using an illuminated iTrackTM 250A microcatheter. Six weeks after surgery, the rabbits were sacrificed and their eyes evaluated for AAV transfection using immunofluorescent antibody staining of GFP. RESULTS: Immunostaining of sectioned and whole-mounted eyes demonstrated robust transfection in all treated eyes, with no fluorescence in untreated control eyes. Transfection occurred diffusely and involved both the choroid and the retina. No apparent adverse effects caused by either the viral vector or the procedure itself could be seen either clinically or histologically. CONCLUSIONS: The ab externo method of delivery using a microcatheter was successful in safely and effectively delivering a gene therapy agent to the suprachoroidal space. This method presents a less invasive alternative to the current method of virally vectored gene delivery.