CHANGES IN SYSTEMIC LEVELS OF VASCULAR ENDOTHELIAL GROWTH FACTOR AFTER INTRAVITREAL INJECTION OF AFLIBERCEPT OR BROLUCIZUMAB FOR NEOVASCULAR AGE-RELATED MACULAR DEGENERATION.

PURPOSE: To analyze and compare the effects of intravitreal brolucizumab versus aflibercept on systemic vascular endothelial growth factor (VEGF)-A levels in patients with neovascular age-related macular degeneration. METHODS: In this prospective interventional case series study, brolucizumab (6.0 mg/50 µL) or aflibercept (2.0 mg/50 µL) was injected intravitreally in 30 patients each. Blood samples were drawn at baseline and 7 days and 28 days after the first injection. Systemic VEGF-A levels were measured using enzyme-linked immunosorbent assay. Thirty healthy individuals served as controls. RESULTS: The median baseline systemic VEGF-A levels in the brolucizumab, aflibercept, and control groups were 10.8 (8.0-13.2), 12.0 (8.0-18.5), and 10.0 (8.0-15.1) pg/mL, respectively (P = 0.315). In the brolucizumab group, VEGF-A levels significantly decreased to 8.0 (8.0-11.5) pg/mL on Day 7 (P = 0.0254) and to 8.0 (8.0-8.0) pg/mL on Day 28 (P < 0.001). In the aflibercept group, VEGF-A levels significantly decreased to 8.0 (8.0-8.0) pg/mL on Day 7 (P < 0.001) but returned to the baseline level, 12.5 (8.5-14.6) pg/mL, on Day 28 (P = 0.120). Vascular endothelial growth factor-A levels were significantly different between the treatment groups after 28 days (P < 0.001). CONCLUSION: Intravitreal brolucizumab resulted in a sustained reduction of systemic VEGF-A levels until 28 days posttreatment, which raises concerns regarding its safety and long-term effects.

Reduced-fluence photodynamic therapy combined with ranibizumab for nonproliferative macular telangiectasia type 2.

PURPOSE: To report the efficacy of reduced-fluence photodynamic therapy (PDT) combined with intravitreal ranibizumab for the treatment of nonproliferative macular telangiectasia (MacTel) type 2. METHODS: Noncomparative, interventional, retrospective case series; 5 eyes of 4 patients were studied. Patients were treated with reduced-fluence PDT and intravitreal ranibizumab within 24 h. After initial treatment, follow-up was at least 12 months in all patients. RESULTS: At baseline median logMAR (logarithm of the minimal angle of resolution) best-corrected visual acuity (BCVA) was 1.0 (range, 1.0-0.3). At 3 months of follow-up vision increased in 3 out of 5 eyes and median BCVA was 0.4 (range, 1.0-0.2). The gain of BCVA ranged from 6 lines to 1 line. Visual acuity remained stable in the other 2 study eyes. No eyes lost vision at 3 months of follow-up. At 12 months of follow-up median logMAR BCVA was 0.7 (range, 1.3-0.3). Two eyes had maintained their gain in BCVA compared to baseline. Two eyes lost vision compared to baseline and 1 eye showed unchanged visual acuity at 12 months of follow-up. CONCLUSION: A combination therapy with reduced-fluence PDT and intravitreal ranibizumab might be a valuable treatment option for eyes with progressive vision loss due to nonproliferative MacTel type 2.

Intravitreal Aflibercept Therapy and Treatment Outcomes of Eyes with Neovascular Age-Related Macular Degeneration in a Real-Life Setting: A Five-Year Follow-Up Investigation.

INTRODUCTION: We aimed to evaluate visual and anatomical outcomes among eyes with neovascular age-related macular degeneration (nAMD) that were persistent to intravitreal aflibercept therapy compared to those that were nonpersistent to therapy. METHODS: We audited 648 treatment-naïve eyes of 559 patients regarding visual acuity (VA) given as the logarithm of the minimum angle of resolution (logMAR) and anatomic outcomes at baseline and at each subsequent follow-up visit for up to 5 years. Nonpersistence was defined as a visit-free interval of > 6 months. RESULTS: Among the enrolled eyes, 405 were persistent to the therapy and 243 (37%) were nonpersistent, of which 161 (66%) eyes returned for further therapy after a gap of clinical care. In the nonpersistent group, we observed a decline from 0.58 ± 0.35 to 0.92 ± 0.57 logMAR (p = 0.01) after 60 months. Compared with the persistent group, the nonpersistent group had worse visual outcomes at their 33-month (p = 0.03), 42-month (p = 0.01), 51-month (p = 0.001) and 60-month (p = 0.01) visits. Additionally, 5/405 (1.2%) eyes in the persistent group and 8/161 (5.0%) eyes in the nonpersistent group developed an end-stage disease with a subfoveal fibrosis during the observational period (p = 0.013). CONCLUSION: We found that eyes with nAMD that were nonpersistent to intravitreal aflibercept therapy experienced statistically significantly worse VA compared to eyes persistent to therapy within 3 years. Moreover, eyes in the nonpersistent group had a four-fold higher risk of developing a fovea-involving fibrosis. Considering the potential irreversible deterioration with respect to best-corrected VA within nAMD, strategies need to be developed for patients at risk of nonpersistence to therapy.

Effects of Intravitreal Aflibercept on the Systemic Insulin-like Growth Factor-I and Vascular Endothelial Growth Factor-A in Patients with Diabetic Retinopathy and Age-Related Macular Degeneration.

PURPOSE: To analyze the effect of intravitreal aflibercept injections on systemic levels of insulin-like growth factor-1 and vascular endothelial growth factor-A in patients with diabetic retinopathy and age-related macular degeneration. METHODS: Vascular endothelial growth factor-A and insulin-like growth factor-1 levels were determined before and one week and four weeks after intravitreal injection of aflibercept (2.0 mg/50 µl) for 19 patients with age-related macular degeneration (mean age, 76 ± 11 years) and 18 patients with diabetic retinopathy (mean age, 64 ± 14 years). Twenty-two healthy individuals were enrolled as controls. RESULTS: A significant decline in systemic vascular endothelial growth factor-A level, from 43 (30-57) pg/ml at baseline to 8 (8-8) pg/ml (p < 0.001) at week one and 17 (8-25) pg/ml (p=0.0054) at week four, was observed in the age-related macular degeneration group. In the diabetic retinopathy group, vascular endothelial growth factor-A levels declined from 53 (35-117) pg/ml to 2 (1-5) pg/ml (p < 0.0001) one week after injection and 16 (13-22) pg/ml four weeks after injection (p=0.0327). At baseline, systemic insulin-like growth factor-1 concentration was higher in the diabetic retinopathy group (57 [37-99] pg/ml) than in the age-related macular degeneration group (35 [24-51] pg/ml) (p=0.0056). A subgroup analysis showed that patients in the proliferative diabetic retinopathy subgroup had significantly higher systemic insulin-like growth factor-1 concentrations (71 [44.7-243] pg/ml) than those in the nonproliferative diabetic retinopathy subgroup (43 [29-66] pg/ml) (p=0.0048). CONCLUSIONS: The difference between the baseline systemic insulin-like growth factor-1 levels of the age-related macular degeneration and diabetic retinopathy groups and the higher insulin-like growth factor-1 levels in the proliferative diabetic retinopathy subgroup one week after aflibercept therapy suggest that insulin-like growth factor-1 may play a role in the pathomechanism of diabetic retinopathy.

Systemic counterregulatory response of angiopoietin-2 after aflibercept therapy for nAMD: a potential escape mechanism.

PURPOSE: To analyse the effect of intravitreal aflibercept injections on systemic angiopoietin-2 (Ang2) and vascular endothelial growth factor (VEGF)-A levels in patients with neovascular age-related macular degeneration (nAMD). METHODS: In a prospective, randomized study, aflibercept (2.0 mg/50 µl) or ranibizumab (0.5 mg/50 µl) was administered intravitreally to 38 treatment-naive patients. Blood samples were taken before, 7 days after, and 28 days after the first intravitreal therapy. Cytokine levels were measured by enzyme-linked immunosorbent assay. Twenty-two age- and sex-matched individuals served as controls. RESULTS: At baseline, there were no significant differences of systemic Ang2 and VEGF-A levels among the treatment and control groups. After intravitreal aflibercept administration, median (interquartile range: IQR) systemic Ang2 was significantly upregulated from 1819 pg/ml (1262-3099) to 2123 pg/ml (1441-3769; p = 0.011) 7 days after the drug injection and remained non-significantly elevated at 1944 pg/ml (1431-2546 pg/ml; p = 0.653) 28 days after the drug injection. Median (IQR) systemic VEGF-A levels were significantly reduced from 43 pg/ml (30-57) to 8 pg/ml (8-8; p < 0.0001) 7 days and 16 pg/ml (8-26; p = 0.001) 28 days after the injection in the aflibercept group. There were no significant effects on systemic VEGF-A and Ang2 levels in the ranibizumab group at any time point following the first injection. CONCLUSION: In this study, we report significant systemic upregulation of Ang2 after intravitreal aflibercept administration. This counterregulatory response may represent a potential escape mechanism from antiangiogenic therapy.

Efficiency benchmarks in the surgical management of primary rhegmatogenous retinal detachment: a monocentric register cohort study of operating room time metrics and influential factors.

OBJECTIVES: To investigate the effect of clinical, methodological and logistic factors on operating room (OR) efficiency in the surgical management of primary rhegmatogenous retinal detachment (RRD). DESIGN: Monocentric retrospective register cohort study. SETTING: Single tertiary centre in the western region of Austria. PARTICIPANTS: We audited patients diagnosed with primary RRD who were treated between January 2014 and August 2019. In total, 783 eyes of 776 consecutive patients were included in this study. Various risk factors affecting OR time efficiency and anatomical success after pars plana vitrectomy (PPV) procedures and scleral buckle (SB) surgery were analysed. PRIMARY AND SECONDARY OUTCOME MEASURES: OR efficiency was the primary outcome measure. Secondary outcome measures were the primary success rate after PPV procedures and SB surgery. RESULTS: PPV was performed in 641 (81.9%) eyes and SB surgery in 142 (18.1%) eyes. Mean surgical times in PPV and SB under retrobulbar anaesthesia (RA) were 74.0 (±32.6) min and 62.1 (±24.6) min (p<0.001), respectively, while under general anaesthesia (GA), these values were 112.0 (±52.0) min and 76.0 (±22.5) min (p<0.001), respectively. A regression analysis revealed the following main risk factors for prolonged OR time for the surgical management of RRD with PPV (all p<0.001): presence of a giant tear (ß=24.01; 32%), proliferative vitreoretinopathy (PVR)-C (ß=16.43; 22%), surgery postponed for 72 hours after diagnosis (ß=21.40; 29%), GA (ß=23.64; 32%) or surgery performed by a trainee (ß=17.35; 23%). PVR (p=0.022) in PPV cases, after-hours settings (p=0.006) and surgeon experience (p=0.030) in SB cases were independent risk factors for reduced success rates. CONCLUSIONS: OR coordinators should consider various independent clinical (giant tear, PVR-C, advanced detachment), methodological (PPV vs SB) and logistic (GA vs RA, after-hours setting and surgeon experience) factors to improve the success rate and surgical management planning of RRD accurately while optimising OR resources and staff efficiency.

Effects of Intravitreal Aflibercept on Galectin-1 and Vascular Endothelial Growth Factor-A Plasma Levels in Patients with Diabetic Retinopathy.

PURPOSE: To analyze the interaction between aflibercept and galectin-1 and evaluate the plasma levels of galectin-1 and vascular endothelial growth factor (VEGF)-A after intravitreal injection of aflibercept in patients with diabetic retinopathy (DR). METHODS: Interaction of galectin-1 with aflibercept was determined via immunoprecipitation. Seventeen patients with type 2 diabetes and diabetic macular edema (DME) were each treated with a single intravitreal injection of aflibercept (2.0 mg, 50 µL) monthly for three consecutive months. Plasma galectin-1 and VEGF-A levels were measured just before an injection was administered, 1 week after the first injection, and 2 months after the last injection. Nineteen age- and sex-matched healthy participants served as controls. RESULTS: Irrespective of the tested galectin-1 concentration, 24% of added galectin-1 was precipitated by aflibercept. Baseline plasma concentrations of galectin-1 were 22.0 and 23.0 ng/mL in the control and aflibercept-treated groups, respectively. Systemic galectin-1 levels increased to 27.0 and 24.0 ng/mL at 7 days and 4 weeks, respectively, after treatment. At week 8, plasma galectin-1 levels significantly increased to 36.0 ng/mL. This level persisted for 20 weeks. Systemic VEGF-A levels significantly reduced to below the minimum detectable dose in 16 DME patients at 7 days after treatment. This level persisted for 4 weeks. Plasma VEGF-A levels were reduced at weeks 8 (p = 0.099) and 20 (p = 0.023). Decreased plasma VEGF-A levels were observed in all patients after treatment. CONCLUSION: We confirmed that physiological aflibercept levels precipitate galectin-1 in in vitro assays. Additionally, systemic upregulation of galectin-1 might be induced by intravitreal aflibercept, which may be relevant in the clinical outcomes of DR treatment.

Iontophoretic delivery of carboplatin in a murine model of retinoblastoma.

PURPOSE: To evaluate the efficacy and dose-response of transcorneoscleral Coulomb controlled iontophoresis (CCI) of carboplatin in the treatment of retinal tumors of a murine model of retinoblastoma. METHODS: Thirty 6-week-old LHBETATAG mice underwent a total of six, serial iontophoretic treatments administered two times per week using a current density of 2.57 mA/cm2 for 5 minutes. Fourteen animals received carboplatin treatments at concentrations of 1.4, 7.0, 10.0, or 14.0 mg/mL without current. Ten control mice underwent treatment with balanced saline solution. RESULTS: A dose-dependent inhibition of intraocular tumor was observed after repetitive iontophoretic treatment. At carboplatin concentrations of 7 mg/mL, 50% of the treated eyes (4/8) exhibited tumor control. No corneal toxicity was observed in eyes treated at carboplatin concentrations under 10 mg/mL. CONCLUSIONS: CCI delivery of carboplatin safely and effectively controls intraocular tumors in a dose-dependent manner in this murine model of retinoblastoma. CCI is a noninvasive, painless option for the focal delivery of carboplatin. However, further clinical and laboratory research is needed before this method of drug delivery is available for children with retinoblastoma.

Systemic counterregulatory response of placental growth factor levels to intravitreal aflibercept therapy.

PURPOSE: Placental growth factor (PlGF) has been implicated as a contributor to resistance against anti-VEGF therapy. The purpose of the present study was to analyze the systemic levels of PlGF, VEGF-A, and VEGF-B in patients with neovascular age-related macular degeneration (AMD) after treatment with aflibercept, ranibizumab, or bevacizumab. METHODS: Totals of 19 patients were treated with intravitreal aflibercept, 19 with ranibizumab, and 18 with bevacizumab. The cytokine levels were measured by ELISA just before the injection, and 7 days and 1 month thereafter. Age- and sex-matched participants (n = 22) served as controls. RESULTS: The median PlGF plasma concentration at baseline was <12.0 pg/mL in the control group as well as in all three anti-VEGF treatment cohorts. After intravitreal aflibercept injection, a significant upregulation of systemic PlGF could be observed in all treated patients (38.0 [31.0-44.0] pg/mL after 1 week [P < 0.001] and 16.0 [0.0-19.0] pg/mL [P = 0.005] after 4 weeks). No significant effects on plasma PlGF concentrations could be detected in those treated with ranibizumab and bevacizumab. The systemic VEGF-A levels were significantly reduced 1 and 4 weeks after intravitreal aflibercept (P < 0.001, P < 0.001) and bevacizumab (P < 0.001, P < 0.01) injections. No significant effects on plasma cytokine concentrations could be observed in the ranibizumab cohort. No significant effects on systemic VEGF-B could be observed in any of the treatment groups. CONCLUSIONS: In this study, we report a significant systemic upregulation of the proangiogenic cytokine PlGF after intravitreal administration of aflibercept. This might represent a counter-regulatory response to antiangiogenic therapy.

Systemic levels of vascular endothelial growth factor before and after intravitreal injection of aflibercept or ranibizumab in patients with age-related macular degeneration: a randomised, prospective trial.

PURPOSE: To evaluate the changes of vascular endothelial growth factor (VEGF) plasma levels after intravitreal injections of aflibercept or ranibizumab in patients with exudative age-related macular degeneration (AMD). METHODS: Thirty-eight patients with exudative AMD were included in this randomised, prospective study. Nineteen patients were randomised to treatment with intravitreal aflibercept (2.0 mg) and 19 to intravitreal ranibizumab (0.5 mg). The concentration of VEGF was measured by ELISA just before the injection, after 7 days and 1 month. Twenty-two age- and sex-matched healthy patients without chorioretinal diseases served as control. RESULTS: The median baseline plasma VEGF concentration was 61.0 pg/ml in the control group, 43.0 pg/ml in the aflibercept group and 59.0 pg/ml in the ranibizumab group (p=0.127). Seven days after intravitreal injection of aflibercept plasma levels were significantly reduced to values below the minimum detectable dose (MDD) in 17 of 19 patients (89.5%) resulting in a median VEGF concentration of <9 pg/ml (p<0.001). The reduction persisted throughout 1 month with values below the MDD in 5 of 19 patients (26.3%) and a median measurement of 17.0 pg/ml (p<0.001). In patients treated with ranibizumab no significant effects could be observed with a baseline VEGF of 59.0 pg/ml, 54.0 pg/ml at 7 days (p=0.776) and 58.5 pg/ml at 4 weeks of follow-up (p=0.670). CONCLUSION: After intravitreal aflibercept injection, the systemic VEGF levels were significantly reduced throughout the observational period of 4 weeks. No significant systemic effects of intravitreal ranibizumab on plasma VEGF were observed.

Systemic upregulation of PDGF-B in patients with neovascular AMD.

PURPOSE: To determine the plasma levels of platelet-derived growth factor-B (PDGF-B), VEGF, and TNF-α in patients with neovascular AMD and in patients with diabetic macular edema (DME). METHODS: Thirty patients with neovascular AMD, 30 patients with DME, and 12 healthy controls were included in this prospective study. The concentrations of PDGF-B, VEGF, and TNF-α were measured by ELISA. RESULTS: The PDGF-B concentration in the plasma of controls was (median [25th-75th percentile]) 263.5 (162.0-513.3) pg/mL and in patients with DME 219.0 (122.8-604.8) pg/mL. In patients with neovascular AMD, PDGF-B levels were significantly higher with a median plasma concentration of 783.5 (289.3-1183.5) pg/mL (P = 0.003). The VEGF concentrations in patients with DME 33.0 (21.8-73.0) pg/mL and in patients with neovascular AMD 55.0 (37.0-116.3) pg/mL showed no significant differences (P = 0.159). A positive correlation of PDGF-B and VEGF plasma levels was found in patients with neovascular AMD and in patients with DME (r = 0.683, P < 0.001, and r = 0.612, P < 0.001, respectively). No significant differences of systemic TNF-α levels could be found between the three study groups. CONCLUSIONS: Patients with neovascular AMD have significantly higher plasma PDGF-B levels compared with patients with DME and healthy controls. Our study data indicate that PDGF-B may be involved in the pathogenesis of neovascular AMD. (https://eudract.ema.europa.eu number, EudraCT 2010-024654-11)

Plasma levels of vascular endothelial growth factor before and after intravitreal injection of bevacizumab, ranibizumab and pegaptanib in patients with age-related macular degeneration, and in patients with diabetic macular oedema.

AIMS: To determine the level of vascular endothelial growth factor (VEGF) in the plasma of patients with diabetic macular edema (DME) and of patients with exudative age-related macular degeneration (ARMD) before and after intravitreal injection of bevacizumab, ranibizumab or pegaptanib. METHODS: 30 patients with DME and 30 patients with ARMD were included in this randomized controlled study. Patients were randomized to treatment with ranibizumab (0.5 mg), bevacizumab (1.25 mg) or pegaptanib (0.3 mg). 10 patients with DME received bevacizumab, 10 ranibizumab and 10 pegaptanib. The same randomized treatment allocation applied to the 30 patients with ARMD. The concentrations of VEGF were measured by ELISA just before the injection, after 7 days and 1 month. RESULTS: Plasma VEGF in patients with exudative ARMD before the injection of bevacizumab was 89.7 pg/ml. It was significantly reduced to 25.1 pg/ml after 7 days (p=0.01), and to 22.8 pg/ml after 1 month (p=0.008). In patients with DME the same systemic reduction by bevacizumab was observed with a significant decrease of baseline VEGF level from 72.2 pg/ml to 13.7 pg/ml after 7 days (p=0.008) and 17.1 pg/ml at 4 weeks with (p=0.012). No significant reductions of plasma VEGF levels were observed in patients receiving ranibizumab or pegaptanib during follow-up. CONCLUSIONS: Bevacizumab significantly reduces the level of VEGF in the blood plasma for up to one month in patients with DME as well as in those with ARMD. No significant systemic effects of intravitreal ranibizumab or pegaptanib on plasma VEGF could be observed.

Long-term outcome after vitrectomy for diabetic macular edema.

BACKGROUND: To determine the benefit of vitrectomy on eyes with diabetic macular edema. METHODS: A retrospective institutional case series was used including 66 patients (69 eyes) who had undergone pars plana vitrectomy for diabetic macular edema between 1992 and 2000. Prior to surgery, the patients had been treated with laser coagulation as recommended by the Early Treatment Diabetic Retinopathy Study. In the case of persistent macular edema, vitrectomy with removal of the posterior hyaloid in all cases and the inner limiting mem brane in 51 (74%) of all cases was performed. RESULTS: The mean preoperative best-corrected visual acuity improved from 20/320 to 20/80 at the time of best postoperative best-corrected visual acuity (p < 0.0001). The mean increase in Snellen lines was 2.7 +/- 7.9. In 90% of eyes, the macular edema improved. A persistence of the edema was observed in 10%. All eyes had at least 12 months of follow-up with a mean of 55 months and a maximum of 120 months. CONCLUSIONS: Our findings confirm that vitrectomy might represent a therapeutic alternative in the case of persisting diabetic macular edema after laser photocoagulation.

Experimental model for proliferative vitreoretinopathy by intravitreal dispase: limited by zonulolysis and cataract.

BACKGROUND: The intravitreal injection of dispase has been shown to be a valuable method for induction of experimental PVR. The goal of the present study was to gain additional information about potential side effects associated with this method. METHODS: Twenty-one pigmented rabbits received a single injection of dispase under topical anesthesia to one eye only, contralateral eyes served as untreated control. The animals were injected with doses from 0.045 to 0.065 units of dispase: 8 animals received 0.045 units, 9 animals 0.055 units and 4 animals 0.065 units. RESULTS: Proliferative vitreoretinopathy occurred in 81% of the treated eyes. In 90% cataract formation was observed. Lens luxation was present in 47.3% of the cataract eyes. CONCLUSION: Intravitreal injection of dispase resulted in the reproducible induction of PVR in addition to cataract formation and lens luxation. Whether these effects may all be associated with a toxic reaction or whether the proliferative changes are solely triggered by endogenous reactions similar to the pathomechanism of human PVR and whether the cataract formation and the lens luxation may be avoided by changing the method of injection require further investigation.

Ocular delivery of acetylsalicylic acid by repetitive coulomb-controlled iontophoresis.

To investigate the potential of transscleral coulomb-controlled iontophoresis (CCI) for repetitive delivery of acetylsalicylic acid (ASA) into the eye, a total of 50 rabbits was included in this study. Fourteen animals received serial CCI treatment. Fourteen animals underwent CCI with either ASA or balanced salt solution (BSS) for at least 6 days at 24- and 48-hour intervals. Eighteen animals received a single CCI application, while 18 animals were injected with 15 mg ASA/kg body weight intravenously. HPLC analysis was performed to determine the levels of salicylic acid (SA) in ocular tissues. Apart from clinical follow-up, 2 rabbits in the ASA and BSS groups were examined by electroretinography, and 2 animals were examined histologically. Though high concentrations of SA were measured, no alterations were observed clinically, histologically and electrophysiologically. Repetitive CCI demonstrated its potential as a topical drug delivery system for ASA into the eye. This transscleral delivery of ASA resulted in significant and sustained intraocular concentrations of SA without side effects. Iontophoresis may be advantageous in clinical administration maintaining therapeutic levels of ASA while avoiding adverse effects associated with the systemic administration of nonsteroidal anti-inflammatory drugs.

Elevated levels of secretoneurin in the rabbit aqueous humor in response to formaldehyde irritation.

BACKGROUND: Secretoneurin, a 33-amino-acid neuropeptide, is generated by proteolytic processing of secretogranin II, which belongs to the chromogranin family. This study aimed to investigate whether secretoneurin is present in the uninflamed rabbit aqueous humor and whether it is released in response to treatment with topical formaldehyde, an agent known to release sensory peptides originating from the trigeminal ganglion. METHODS: Blood samples and aqueous humor of eyes pretreated with neutral formaldehyde and untreated controls were analyzed for secretoneurin immunoreactivity by a highly sensitive radioimmunoassay. Furthermore, the molecular form of the secretoneurin immunoreactivity was characterized by gel filtration high-performance liquid chromatography (HPLC). RESULTS: In the blood, secretoneurin levels were found to be below the detection limit of 2 fmol/100 microl. In the aqueous humor, secretoneurin-immunoreactivity was detected in moderate but significant amounts. The mean concentration of secretoneurin was 8.1 (+/-0.34) fmol/100 microl in controls and 7.8 (+/-0.1) fmol/100 microl 15 min after formaldehyde application. Thirty minutes after treatment, the secretoneurin levels were significantly elevated by 63%. Gel filtration HPLC revealed that the main molecular form corresponded to the free peptide secretoneurin. CONCLUSIONS: The neuropeptide secretoneurin has been detected in the anterior segment of the eye for the first time. The elevation of secretoneurin in formaldehyde-treated eyes may be induced by an enhanced release from the iris/ciliary body complex, as formaldehyde is known to provoke neurogenic inflammation in the anterior segment via release of sensory peptides originating from the trigeminal ganglion. This is why our results indicate a sensory origin of secretoneurin in the eye.