Retinal and choroidal changes after anti-VEGF therapy in neovascular-AMD patients: A systematic review and meta-analysis of SD-OCT studies.

BACKGROUND: In recent years, the progress made in the field of optical coherence tomography has helped to understand the changes in eye layers in patients with exudative age-related macular degeneration (nAMD). Early diagnosis of nAMD, a leading cause of irreversible vision impairment, is helpful. Therefore, we performed a meta-analysis on OCT measurement alterations before and after anti-VEGF therapy in patients with nAMD and controls. METHOD: We systematically searched Scopus, PubMed, Cochrane, and Web of Science to find articles that measured choroidal and retinal layer changes after anti-VEGF therapy in nAMD Patients. We chose either a fixed-effects or random-effects model based on the assessed heterogeneity level to perform a meta-analysis. In addition, we conducted meta-regression, subgroup analyses, publication bias, and quality assessment for included studies. RESULTS: Thirteen studies were included in the meta-analysis, with 733 total participants. Foveal thickness and subfoveal choroidal thickness (CT) decreased significantly in the first 3 years after injections, except for subfoveal CT in the third year after injection. It also showed that CT at 1500 µm temporal and nasal to the fovea did not significantly change. CONCLUSION: Our results showed anti-VEGF treatment for nAMD patients was associated with a significant reduction in foveal thickness and subfoveal CT in the first 2 years after treatment. Our analysis did not reveal any correlation between changes in foveal thickness and subfoveal CT with best-corrected visual acuity or other factors.

Severe Intraocular Inflammation Following Intravitreal Faricimab.

Importance: Monitoring for and reporting potential cases of intraocular inflammation (IOI) in clinical practice despite limited occurrences in clinical trials, including experiences with relatively new intravitreal agents, such as brolucizumab, pegcetacoplan, or faricimab, helps balance potential benefits and risks of these agents. Objective: To provide descriptions of 3 initially culture-negative cases of acute, severe, posterior-segment IOI events occurring within the same month following intravitreal faricimab injections at a single institution. Design, Setting, and Participants: In this case series, 3 patients manifesting acute, severe IOI following intravitreal injection of faricimab were identified between September 20, 2023, and October 20, 2023. Exposure: Faricimab, 6 mg (0.05 mL of 120 mg/mL solution), for neovascular age-related macular degeneration among patients previously treated with aflibercept; 1 patient also had prior exposure to bevacizumab. Main Outcomes and Measures: Visual acuity, vitreous taps for bacterial or fungal cultures, and retinal imaging. Results: All 3 patients received intravitreal faricimab injections between September 20 and October 20, 2023, from 2 different lot numbers (expiration dates, July 2025) at 3 locations of 1 institution among 3 of 19 retina physicians. Visual acuities with correction were 20/63 OS for patient 1, 20/40 OD for patient 2, and 20/20 OS for patient 3 prior to injection. All 3 patients developed acute, severe inflammation involving the anterior and posterior segment within 3 to 4 days after injection, with visual acuities of hand motion OS, counting fingers OD, and hand motion OS, respectively. Two patients were continuing faricimab treatment while 1 patient was initiating faricimab treatment. All received intravitreal ceftazidime, 2.2 mg/0.1 mL, and vancomycin, 1 mg/0.1 mL, immediately following vitreous taps. All vitreous tap culture results were negative. One patient underwent vitrectomy 1 day following presentation. Intraoperative vitreous culture grew 1 colony of Staphylococcus epidermidis, judged a likely contaminant by infectious disease specialists. All symptoms resolved within 1 month; visual acuities with correction were 20/100 OS for patient 1, 20/50 OD for patient 2, and 20/30 OS for patient 3. Conclusions and Relevance: In this case series, 3 patients with acute, severe IOI within 1 month at 3 different locations among 3 ophthalmologists of 1 institution following intravitreal faricimab could represent some unknown storage or handling problem. However, this cluster suggests such inflammatory events may be more common than anticipated from faricimab trial reports, emphasizing the continued need for vigilance to detect and report such cases following regulatory approval.

Ocular, Visual, and Anatomical Outcomes in Eyes Requiring Incisional Intraocular Pressure-Lowering Surgery Following the 0.19-mg Fluocinolone Acetonide Intravitreal Implant.

BACKGROUND AND OBJECTIVE: To assess ocular, visual, and anatomical outcomes following the 0.19-mg fluocinolone acetonide (FAc) intravitreal implant (ILUVIEN®) and incisional intraocular pressure (IOP)-lowering surgery in diabetic macular edema. PATIENTS AND METHODS: From a 36-month, phase 4, open-label, observational study (N = 202 eyes, 159 patients), 8 eyes (7 patients) required IOP-lowering surgery post-FAc; eyes were segregated by FAc-induced (n = 5, 2.47%) versus neovascular glaucoma (NVG)-related (n = 3, 1.49%) IOP elevations and assessed for IOP, best corrected visual acuity (BCVA), central subfield thickness (CST), and cup-to-disc ratio (c/d). RESULTS: Changes at 36 months were +5.4 letters BCVA (P > 0.05) and +0.09 c/d (P = 0.0217); IOP and CST were unchanged. FAc-induced-group eyes required fewer IOP-lowering medications than NVG-group eyes (2.0 versus 4.0; P < 0.01) but for longer duration (15.2 versus 2.6 months; P < 0.001). CONCLUSIONS: Post-FAc IOP-lowering surgery, regardless of cause, largely did not affect the outcomes measured; these procedures, then, may not meaningfully threaten positive outcomes. [Ophthalmic Surg Lasers Imaging Retina 2024;55:22-29.].

STAT3 phosphorylation at serine 727 activates specific genetic programs and promotes clear cell renal cell carcinoma (ccRCC) aggressiveness.

The signal transducer and activator of transcription 3 (STAT3) is a transcription factor mainly activated by phosphorylation in either tyrosine 705 (Y705) or serine 727 (S727) residues that regulates essential processes such as cell differentiation, apoptosis inhibition, or cell survival. Aberrant activation of STAT3 has been related to development of nearly 50% of human cancers including clear cell renal cell carcinoma (ccRCC). In fact, phosho-S727 (pS727) levels correlate with overall survival of ccRCC patients. With the aim to elucidate the contribution of STAT3 phosphorylation in ccRCC development and progression, we have generated human-derived ccRCC cell lines carrying STAT3 Y705 and S727 phosphomutants. Our data show that the phosphomimetic substitution Ser727Asp facilitates a pro-tumoral phenotype in vitro, in a Y705-phosphorylation-independent manner. Moreover, we describe that STAT3 phosphorylation state determines the expression of different subsets of target genes associated with distinct biological processes, being pS727-dependent genes the most related to cellular hallmarks of cancer. In summary, the present study constitutes the first analysis on the role of overall STAT3 phosphorylation state in ccRCC and demonstrates that pS727 promotes the expression of a specific subset of target genes that might be clinically relevant as novel biomarkers and potential therapeutic targets for ccRCC.

Treating patients with geographic atrophy: are we there yet?

Geographic atrophy (GA) is a progressive degenerative disease that significantly contributes to visual impairment in individuals aged 50 years and older. The development of GA is influenced by various modifiable and non-modifiable risk factors, including age, smoking, and specific genetic variants, particularly those related to the complement system regulators. Given the multifactorial and complex nature of GA, several treatment approaches have been explored, such as complement inhibition, gene therapy, and cell therapy. The recent approval by the Food and Drug Administration of pegcetacoplan, a complement C3 inhibitor, marks a significant breakthrough as the first approved treatment for GA. Furthermore, numerous interventions are currently in phase II or III trials, alongside this groundbreaking development. In light of these advancements, this review provides a comprehensive overview of GA, encompassing risk factors, prevalence, genetic associations, and imaging characteristics. Additionally, it delves into the current landscape of GA treatment, emphasizing the latest progress and future considerations. The goal of starting this discussion is to ultimately identify the most suitable candidates for each therapy, highlight the importance of tailoring treatments to individual cases, and continue monitoring the long-term implications of these emerging interventions.

Current Management of Subretinal Hemorrhage in Neovascular Age-Related Macular Degeneration.

Age-related macular degeneration (AMD) is the leading cause of irreversible vision loss among individuals aged 65 years and older in the USA. For individuals diagnosed with AMD, approximately 12% experience varying levels of subretinal hemorrhage (SRH), which can be further classified by size into small, medium, and massive measured in disc diameters. SRH is an acute and rare sight-threatening complication characterized by an accumulation of blood under the retina arising from the choroidal or retinal circulation. Released iron toxins, reduced nutrient supply, fibrin meshwork contraction, and outer retinal shear forces created by SRH contribute to visual loss, macular scarring, and photoreceptor damage. SRH treatment strategies aim to displace hemorrhage from the foveal region and prevent further bleeding. Although there are no standardized treatment protocols for SRH, several surgical and nonsurgical therapeutical approaches may be employed. The most common surgical approaches that have been utilized are pars plana vitrectomy (PPV) combined with multiple maneuvers such as the removal of choroidal neovascularization lesions, macular translocation, retinal pigment epithelium patch repair, SRH drainage, intravitreal injection of recombinant-tissue plasminogen activator (tPA), expansile gas and air displacement, and anti-vascular endothelial growth factor (anti-VEGF) injections. Nonsurgical therapeutical approaches include intravitreal anti-VEGF monotherapy, intravitreal tPA administration without PPV, and photodynamic therapy. This review article aims to explore the current treatment strategies and supporting literature regarding both surgical and nonsurgical, of SRH in patients with AMD. Moreover, this article also aims to highlight the distinct treatment modalities corresponding to different sizes of SRH.

Early Vitrectomy for Endophthalmitis: Are EVS Guidelines Still Valid?

BACKGROUND: Endophthalmitis, a potentially sight-threatening condition, remains a challenge for ophthalmologists worldwide. The endophthalmitis vitrectomy study (EVS) conducted in 1995 compared vitrectomy and intravitreal antibiotic injections to intravitreal antibiotic injections alone for acute post-cataract surgery and secondary intraocular lens endophthalmitis, setting treatment guidelines. However, the landscape of clinical practice has evolved considerably since then, raising questions about the applicability of EVS recommendations today. SUMMARY: Recent studies have proposed that early and complete vitrectomy (CEVE) could potentially be an effective approach for managing endophthalmitis cases, irrespective of the initial visual acuity. However, it is important to note that the level of rigor in these recent studies may not match that of the EVS study, and as such, this assertion should be considered with caution. Furthermore, the EVS study exclusively focused on post-cataract surgery cases, leaving other endophthalmitis types, like post-intravitreal injection and post-traumatic endophthalmitis, without standardized treatment guidelines. Research exploring the role of early vitrectomy in these contexts yields mixed results, emphasizing the need for further investigation and well-designed prospective trials. Endogenous endophthalmitis, originating from systemic infections, adds complexity to the scenario. While early vitrectomy shows promise in specific cases, conflicting evidence necessitates comprehensive research. KEY MESSAGES: This review underscores the necessity for tailored treatment strategies, supporting early vitrectomy when clinically indicated, and advocating for prospective trials to clarify its role in diverse endophthalmitis scenarios. As surgical techniques and antimicrobial therapies continue to advance, reevaluating treatment paradigms becomes crucial to enhance patient outcomes and protect ocular health.

Artificial intelligence in retinal image analysis: Development, advances, and challenges.

Modern advances in diagnostic technologies offer the potential for unprecedented insight into ophthalmic conditions relating to the retina. We discuss the current landscape of artificial intelligence in retina with respect to screening, diagnosis, and monitoring of retinal pathologies such as diabetic retinopathy, diabetic macular edema, central serous chorioretinopathy, and age-related macular degeneration. We review the methods used in these models and evaluate their performance in both research and clinical contexts and discuss potential future directions for investigation, use of multiple imaging modalities in artificial intelligence algorithms, and challenges in the application of artificial intelligence in retinal pathologies.

Surgical Management of Diabetic Macular Edema.

PURPOSE OF REVIEW: Diabetic macular edema (DME) is the accumulation of fluid in the extracellular space within the macula and is a major cause of visual impairment among patients with diabetes. First-line treatment for DME includes pharmacotherapy with intravitreal anti-vascular endothelial growth factor medications and intravitreal corticosteroids. Alternative therapeutic strategies include laser photocoagulation for non-center involving DME, and surgical options such as pars plana vitrectomy (PPV) with or without internal limiting membrane (ILM) peel in cases with vitreoretinal interface anomalies or DME refractory to pharmacotherapy, and the Port Delivery System (PDS) for sustained release of anti-vascular endothelial growth factor (VEGF) medication. Our aim is to review the existing literature on surgical management of DME including imaging changes in chronic DME and the clinical relevance of surgical intervention. RECENT FINDINGS: Imaging changes associated with DME and a worse prognosis include disorganization of the retinal layer, disruption of both the external limiting membrane (ELM) and ellipsoid zone, and vitreomacular interface abnormalities. Studies involving pars plana vitrectomy with and without ILM peel show anatomic improvement but may not always be associated with significant change in visual outcomes. Early studies lacked detailed imaging of the retinal layers and PPV was likely performed as a last resort. In addition, the novel PDS is surgically implanted into the pars plana and works as a drug reservoir with controlled release of drug. However, it has been recalled in patients with wet age-related macular degeneration due to issues with dislodgement. Surgical interventions for DME include pars plana vitrectomy with and without ILM peel and new surgical therapies for DME such as the PDS and subretinal gene therapy have the potential to reduce the risk of DME progression.

International Validation of Myopic Traction Maculopathy Staging System.

BACKGROUND AND OBJECTIVE: The aim of this study was to evaluate the interobserver agreement of the myopic traction maculopathy (MTM) staging system (MSS). PATIENTS AND METHODS: Each observer was asked to look at the MSS Table and then identify, in each optical coherence tomography scan, one among four stages of MTM in the retina, one among three stages in the fovea, and, as secondary findings, the presence or absence of an outer lamellar macular hole and the presence or absence of epiretinal abnormalities. The interobserver agreement value was calculated using the Gwet's AC1 unweighted and AC2 weighted statistics. The outcomes were interpreted as poor (<0.00), slight (0.00 to 0.20), fair (0.21 to 0.40), moderate (0.41 to 0.60), substantial (0.61 to 0.80), or almost perfect (0.81 to 1.00) agreement. RESULTS: The agreement, among 65 participants, was 0.62 (AC1) and 0.77 (AC2) for the retina stage; 0.63 (AC1) and 0.81 (AC2) for the fovea stage; 0.56 (AC1) for the outer lamellar macular hole; and 0.26 (AC1) for epiretinal abnormalities. CONCLUSION: The MSS is highly reproducible and helps ophthalmologists to share information on MTM in a more accurate and reliable way. [Ophthalmic Surg Lasers Imaging Retina 2023;54(3):153-157.].

Endophthalmitis Following Inadvertent Intraocular Botulinum Toxin A Injection.

Botulinum toxin A injection is a safe alternative procedure to surgery in the management of different types of strabismus. Serious complications such as globe perforation are rare in expert hands. The authors report a case of a child known to have a muscle-eye-brain disease with high myopia who developed endophthalmitis following inadvertent penetrating intraocular botulinum toxin A injection for strabismus correction. To their knowledge, this serious complication after penetrating botulinum toxin A injection has not been previously reported. [J Pediatr Ophthalmol Strabismus. 2023;60(2):e8-e10.].

DIRECT MACULAR HOLE MANIPULATION RESULTS IN HIGH SUCCESS RATE IN SECONDARY MACULAR HOLE REPAIR.

PURPOSE: To investigate closure rates and functional outcomes of surgery for refractory and recurrent macular holes (MHs) in a real-world setting. METHODS: Retrospective review of secondary MH surgeries. RESULTS: A total of 72 eyes from 72 patients were included. Eyes had a mean of 1.51 surgeries before inclusion into this study with a mean MH size of 762 µ m and a mean baseline logarithm of the minimum angle of resolution best-corrected visual acuity of 1.11 (∼20/260 Snellen). Closure rates were 89.3% for tissue transplantation, 77.3% for internal limiting membrane (ILM) flaps, 92.9% for MH manipulation, and 12.5% for repeat ILM peeling ( P < 0.05). Best-corrected visual acuity changes in logarithm of the minimum angle of resolution from baseline to postoperative month six were +0.29 for ILM peeling alone (15 Early Treatment Diabetic Retinopathy Study letters worse), -0.39 for MH manipulation (20 Early Treatment Diabetic Retinopathy Study letters improved), -0.23 for tissue transplantation (13 Early Treatment Diabetic Retinopathy Study letters improved), and -0.2 for ILM flaps (10 Early Treatment Diabetic Retinopathy Study letters improved; P < 0.05). CONCLUSION: Secondary MH closure is possible using various surgical techniques with acceptable anatomical closure rates. Repeat ILM peeling is associated with the lowest closure rates and poorest functional results. To distinguish between techniques would require a large sample size of approximately 750 eyes.

Surgery for Infectious Retinitis - When Medical Therapy Is Not Sufficient: The Moacyr E. Alvaro Pan-American Lecture 2023.

BACKGROUND: Viral retinitis composes a group of infectious ocular diseases with poor prognoses. With the advent of antivirals and HAART, the treatment of these diseases has evolved and ocular outcomes have improved. However, even with prompt medical treatment, a significant number of patients will experience complications that require surgical intervention. While there has been an abundance of research examining the medical treatment of CMV retinitis and acute retinal necrosis, the research examining surgical outcomes of complications such as retinitis-associated retinal detachment is comparatively limited. METHODS: Literature review. RESULTS: In this review, we discuss the current literature examining treatment of CMV retinitis and acute retinal necrosis, with a focus on surgical management of complications such as retinal detachment. CONCLUSIONS: Despite significant improvements in the medical treatment of CMV retinitis and ARN over the last three decades, vision-threatening complications such as retinal detachment are relatively common and require surgical management via PPV, laser photocoagulation, and intraocular gas or silicone oil tamponade.

Pneumatic Retinopexy Versus Pars Plana Vitrectomy for the Management of Retinal Detachment: A Systematic Review and Meta-Analysis.

INTRODUCTION: Pneumatic retinopexy (PnR) was proposed as an alternative to pars plana vitrectomy (PPV) in certain circumstances. PnR is an outpatient procedure and more cost-effective. However, its benefits should be judged alongside its success rate and adverse events. Herein, we compare the efficacy and safety of PnR and PPV for rhegmatogenous retinal detachment (RRD) repair. METHODS: We searched the PubMed, Scopus, EMBASE, Web of Science, Cochrane, and Google Scholar databases. Observational and interventional studies comparing the efficacy and safety of PnR and PPV were included. The outcomes were the success rate of the treatment, improvement in visual acuity, and adverse event rates. Subgroup analysis was performed based on the lens and macula status. Eleven articles were eligible to enter our study; these consisted of 11,346 patients with a mean age of 74.1. RESULTS: PnR was superior to PPV in terms of retinal displacement, photoreceptor integrity, visual function, and vertical metamorphopsia scores. In the meta-analysis, PPV showed higher a reattachment rate than PnR (OR = 3.39, 95% CI 2.25-5.11). Subgroup analysis showed that the advantage of PPV over PnR was more pronounced in studies with fewer phakic eyes, more macula-on patients, and in cases with primary PnR failure. While PnR patients had better pre-op (SMD = - 0.58, 95% CI = - 1.16 to 0.00) and post-op (SMD = - 0.45, 95% CI = - 0.60 to - 0.30) LogMAR, the improvement in visual acuity after surgery was higher in PPV patients (SMD = 0.49, 95% CI = - 0.15 to 1.13). CONCLUSION: The success rate of PnR was higher in studies published after 2015 compared to previous studies (82% vs. 59%). Cataract formation and surgery were significantly higher in the PPV arm, while the occurrence of new retinal tears was more frequent in the PnR group. PnR can be used as the primary procedure for RRD repair in selected cases. However, we propose some modifications to the PIVOT criteria, e.g., the exclusion of cases presenting with several risk factors of poor outcomes.

Iron cycle disruption by heme oxygenase-1 activation leads to a reduced breast cancer cell survival.

Heme oxygenase-1 (HO-1), which catalyzes heme degradation releasing iron, regulates several processes related to breast cancer. Iron metabolism deregulation is also connected with several tumor processes. However the regulatory relationship between HO-1 and iron proteins in breast cancer remains unclear. Using human breast cancer biopsies, we found that high HO-1 levels significantly correlated with low DMT1 levels. Contrariwise, high HO-1 levels significantly correlated with high ZIP14 and prohepcidin expression, as well as hemosiderin storage. At mRNA level, we found that high HO-1 expression significantly correlated with low DMT1 expression but high ZIP14, L-ferritin and hepcidin expression. In in vivo experiments in mice with genetic overexpression or pharmacological activation of HO-1, we detected the same expression pattern observed in human biopsies. In in vitro experiments, HO-1 activation induced changes in iron proteins expression leading to an increase of hemosiderin, ROS levels, lipid peroxidation and a decrease of the growth rate. Such low growth rate induced by HO-1 activation was reversed when iron levels or ROS levels were reduced. Our findings demonstrate an important role of HO-1 on iron homeostasis in breast cancer. The changes in iron proteins expression when HO-1 is modulated led to the iron accumulation deregulating the iron cell cycle, and consequently, generating oxidative stress and low viability, all contributing to impair breast cancer progression.

Combined Therapeutic Penetrating Keratoplasty and Pars Plana Vitrectomy for the Treatment of Infectious Keratitis Endophthalmitis: Mexican Endophthalmitis Study Group Protocol 4.

PURPOSE: The purpose of this study was to assess the role of combined surgical treatment of therapeutic penetrating keratoplasty and pars plana vitrectomy in the anatomical and functional outcome of infectious keratitis endophthalmitis. METHODS: This study reviewed the medical records of 4 participating centers in the United States and Mexico. This study included patients with a clinical diagnosis of infectious keratitis endophthalmitis who had been treated with an early therapeutic penetrating keratoplasty and pars plana vitrectomy as the main treatment for endophthalmitis. From each medical record, the study retrieved demographic data, relevant medical and drug history, baseline clinical manifestation of endophthalmitis, best-corrected visual acuity, and the need for enucleation/evisceration for the control of the infection or any other reason through the follow-up. RESULTS: The study included 48 patients (50.15 ± 20.6 years). The mean follow-up time was 13 ± 0.5 months. The mean best-corrected visual acuity at baseline was 2.1 ± 0.25 logarithm of the minimum angle of resolution. At month 12 was 2.09 ± 0.61 logarithm of the minimum angle of resolution ( P = 0.9). The overall prevalence of enucleation/evisceration was 8.3% (95% confidence interval: 2.32%-19.98%). The prevalence of a vision of no-light perception was 20.8% (95% confidence interval: 2.32%-19.98%). CONCLUSIONS: Combined surgery for severe cases of infectious keratitis endophthalmitis eradicates the infection in most cases, while significantly improving the overall outcomes.

Aplicación del Método Hectárea de Hábitat en compensación ambiental: El caso del Embalse Río Piedras, Costa Rica

Introducción: La compensación ambiental es la alternativa final para enfrentar los impactos de proyectos de desarrollo que no pueden ser evitados, reducidos o mitigados. La compensación de hábitats pretende sustituir recursos ecológicamente equivalentes. El Método Hectárea de Hábitat se diseñó inicialmente para evaluar la equivalencia ecológica de vegetación nativa y emplea puntajes de indicadores relativos a un hábitat de referencia. La suma de estos puntajes mide la condición estructural del ambiente de manera relativa a la referencia, cuantificando el número de hectáreas necesarias para compensar la pérdida de un hábitat similar. Aunque el método no está exento de limitaciones, los valores se pueden estimar a partir de datos de campo recogidos sin ambigüedad, de forma reproducible, con menos sesgos que métodos más cualitativos. En este artículo, usamos una modificación del Método Hectárea de Hábitat para determinar el área equivalente necesaria para compensar la pérdida de hábitat en un área silvestre protegida en Costa Rica. Metodología: Trabajamos en la Reserva Biológica Lomas de Barbudal, Pacífico norte de Costa Rica, un área silvestre protegida donde se inundarán cerca de 113 hectáreas para el Embalse de Río Piedras. En una propiedad previamente identificada como un sitio potencial de compensación, evaluamos indicadores de paisaje, suelo, estructura de la vegetación y servicios ecosistémicos; asignamos los puntajes en relación con el sitio a inundar. Resultados: El puntaje de la condición ambiental en el sitio de compensación fue de 44,7% (±15,9%) del sitio inundado. En consecuencia, considerando la incertidumbre de nuestras mediciones, compensar la pérdida de cada hectárea requeriría entre 2.23 y 3.49 hectáreas de un ambiente similar. Conclusión: Se necesitan entre 2.23 y 3.49 hectáreas de reemplazo, para compensar la pérdida de hábitat en el Embalse de Río Piedras.

Introduction: Environmental compensation is the final alternative to face the impacts of development projects that cannot be avoided, reduced, or mitigated. The offset of affected habitats or environmental elements usually substitutes ecologically equivalent resources. The Habitat-Hectare Method was initially designed to assess the ecological equivalence of native vegetation, and employs indicator scores relative to a reference habitat. The sum of these scores measures the structural condition of the environment against the reference, quantifying the number of hectares needed to compensate for the loss of similar habitat. Although it is not exempt from limitations, the values can be estimated from field data collected without ambiguity, in a reproducible way, with less bias than more qualitative methods. In this paper, we use a modification of the Habitat-Hectare Method to determine the equivalent area needed to compensate for habitat loss in a protected wilderness in Costa Rica. Methods: We worked in the Lomas de Barbudal Biological Reserve, north Pacific of Costa Rica, a protected wilderness where nearly 113 hectares will be flooded for the Río Piedras Reservoir. In a property previously identified as a potential compensation site, we assessed indicators for landscape, soil, vegetation structure, and ecosystem services; the scores were assigned in relation to the environment found at the flood site. Results: The environmental condition score at the compensation site was 44.7% (±15.9%) of the impact site. Consequently, considering the uncertainty in our measurements, compensating for the loss of each hectare would require between 2.23 and 3.49 hectares of a similar environment. Conclusion: Between 2.23 and 3.49 hectares of are needed to compensate for the loss of habitat in the Río Piedras Reservoir.

Uso de la diversidad biológica de grupos indicadores para evaluar la compensación ecológica: el caso del Embalse Río Piedras, Costa Rica

Introducción: Cerca de 113 hectáreas dentro de la Reserva Biológica Lomas de Barbudal (RBLB) se inundarían si se llegara a establecer el embalse de riego Río Piedras en el noroeste de Costa Rica. Ante ese impacto inevitable, la legislación costarricense requiere evaluar la pérdida de diversidad en el sitio y compensarla siguiendo el principio de equivalencia ecológica. Objetivo: Nuestro objetivo fue evaluar la pérdida de diversidad en el sitio y, valorar esta condición en una propiedad privada adyacente considerada como sitio potencial para compensar por esas pérdidas. Metodología: La diversidad, composición y prioridad de conservación de plantas vasculares, fauna vertebrada y artrópodos del sotobosque fueron evaluadas en el sitio de inundación en RBLB y en una propiedad privada adyacente identificada como sitio potencial de compensación. La equivalencia en diversidad entre ambos sitios se valoró mediante un procedimiento que asigna puntajes a los diferentes indicadores del sitio de compensación respecto a los observados en RBLB. La suma de esos puntajes representa la condición de diversidad del sitio de compensación y puede utilizarse como criterio para fundamentar acciones resarcitorias. Resultados: Todos los grupos sustitutos registraron un alto número de especies, aunque la información aportada por las plantas herbáceas, los mamíferos no voladores y los reptiles fue limitada. En contraste, los otros grupos indican una mayor diversidad en el sitio potencial de inundación, atribuida a sutiles diferencias ambientales y a su mejor conservación. En consecuencia, se valoró sustituir el área afectada por un área mayor del sitio de compensación para resarcir las perdidas en diversidad estimadas. Conclusión: Nuestro análisis muestra que grupos sustitutos pueden ser empleados en estudios ambientales a corto plazo. Sin embargo, los grupos a utilizar deben seleccionarse cuidadosamente, considerando los objetivos y el alcance del proyecto. Cuantificar la condición de diversidad del sitio de compensación respecto a la que se encuentra en un sitio de referencia parece ser un procedimiento válido, repetible y evaluable que permite establecer criterios sobre los cuales basar medidas resarcitorias.

Introduction: About 113 hectares within the Lomas de Barbudal Biological Reserve (RBLB) would be flooded if the Río Piedras irrigation reservoir were established in northwestern Costa Rica. Given this inevitable impact, Costa Rican legislation requires evaluating the loss of diversity in the site and compensating for it following the principle of ecological equivalence. Objetive: Our goal was to assess the loss of diversity at that site and evaluate the condition of an adjacent private property as a potential site to compensate for those losses. Methodology: The diversity, composition, and conservation priority of vascular plants, vertebrate fauna, and understory arthropods were assessed at the RBLB flood site and on an adjacent private property identified as a potential offset site. The equivalence in diversity between both sites was evaluated by assigning scores to the different indicators at the compensation site concerning those observed in RBLB. The sum of these scores represents the diversity condition of the compensation site and can be used as a criterion to support compensatory actions. Results: All surrogate groups recorded a high number of species, although the information provided by herbaceous plants, non-flying mammals, and reptiles was limited. In contrast, the other groups indicate a greater diversity in the potential flood site, attributed to subtle environmental differences and the better conservation at this site. Consequently, it was assessed to replace the affected area with a larger offset site area to compensate for the estimated losses in diversity. Conclusion: Our analysis shows that surrogate groups can be used in short-term environmental studies. However, the groups to be used must be carefully selected, considering the objectives and scope of the project. Quantifying the diversity condition of the compensation site concerning that found in a reference site seems to be a valid, repeatable, and evaluable procedure that allows establishing criteria on which to base compensatory measures.

Compensación ambiental por la segregación y uso de un área dentro de un refugio de vida silvestre: un caso de estudio empleando coste de oportunidad

Introducción: El establecimiento del Puesto Fronterizo Las Tablillas implica la segregación de 12.12 ha del Refugio Nacional de Vida Silvestre Corredor Fronterizo (RNVSCF), en el norte de Costa Rica. El sitio tiene una larga historia de uso de la tierra y su entorno natural está muy degradado. Este es un caso que se puede abordar desde el coste de oportunidad que se refiere al valor de la alternativa a la que se renuncia al tomar una decisión económica. Objetivo: En este artículo, usamos este precepto para evaluar la compensación por pérdidas en la estructura del hábitat y la biodiversidad si se interrumpiera la dinámica de sucesión dentro de un área silvestre protegida. Métodos: Para encontrar la ganancia neta en compensación requerida por dicha segregación, analizamos la diversidad y composición de la cubertura forestal cercana para pronosticar el ambiente que se perdería si se interrumpieran sus objetivos de conservación (costo de oportunidad). Compensar estas pérdidas requiere un ambiente equivalente, por lo que seleccionamos dos propiedades, entre 27 investigadas adyacentes al RNVSCF, que comparten cobertura forestal, están registradas legalmente y poseen atributos ambientales favorables para el diseño de reservas. Las dos propiedades seleccionadas y el sitio Las Tablillas fueron caracterizados a nivel de atributos geológicos e hidrológicos y de composición biológica de grupos indicadores. Resultados: Ambas propiedades son física y biológicamente favorables para el intercambio. La escogencia de cualquiera aumentaría el área del RNVSCF en más de 100 ha de un ambiente con mejor cobertura, más diversidad y mejor conexión con otras masas forestales que el observado en el sitio de segregación. Esto es una ventaja para el objetivo de conservación del refugio. Conclusión: En este caso, el coste de oportunidad favoreció la ganancia ambiental para la propuesta de compensación y podría ser utilizado para evaluar otras compensaciones que involucren ambientes sensibles o protegidos.

Introduction: The establishment of the Las Tablillas Border Post implies the segregation of 12.12 ha within the National Wildlife Refuge Border Corridor (RNVSCF) in northern Costa Rica. The site has a long land use history, so its environment is highly degraded. This case can be studied from the opportunity cost, which refers to the amount of the alternative given up when making an economic decision. Objective: In this paper, we use this precept to assess the compensation for losses in habitat structure and biodiversity if succession dynamics within a protected wilderness area were interrupted. Methods: To find the net gain in compensation required by this segregation, we analyzed the diversity and composition of nearby forest cover to forecast the environment that would be lost if its conservation objectives were interrupted (opportunity cost). Compensating for these losses requires an equivalent environment, so we selected two properties, among the 27 investigated, that shared forest cover, are located adjacent to the RNVSCF, are registered, and possess other attributes favorable to the design of reserves. The two selected properties and the Las Tablillas site were characterized at the level of geological and hydrological attributes and the composition of indicator groups. Results: Both properties are physically and biologically favorable for the exchange. It would increase the area of the RNVSCF by more than 100 ha of an environment with better coverage, more diversity, and a better connection to other forest masses than the one observed in the segregation site, which is an advantage to the conservation objective of the refuge. Conclusion: In this case, the opportunity cost favored the environmental gain for the offset proposal and could be used to evaluate other compensation involving sensitive or protected environments.