Subconjunctival Sirolimus-Loaded Liposomes for the Treatment of Moderate-to-Severe Dry Eye Disease.

Purpose: To determine the effectiveness of subconjunctival application of a novel sirolimus liposomal formulation for the treatment of dry eye. Methods: A randomized, triple-blind, Phase II clinical trial. Thirty-eight eyes of 19 patients were included. Nine patients (18 eyes) assigned to the sham group (Sham) and 10 patients (20 eyes) to sirolimus-loaded liposomes group (Sirolimus). The treatment group received three doses of subconjunctival liposome-encapsulated sirolimus and the sham group received three doses of liposomal suspension without sirolimus. Subjective (Ocular Surface Disease Index, OSDI) and measured (corrected distance visual acuity, conjunctival hyperemia, tear osmolarity, Schirmer's test, corneal/conjunctival staining and matrix metalloproteinase-9) variables were measured. Results: Sirolimus-entrapped liposomes-treated group OSDI scores changed from 62.19 (± 6.07) to 37.8 (± 17.81) (p=0.0024), and conjunctival hyperemia from 2.0 (± 0.68) to 0.83 (± 0.61) (p<0.0001); Sham group with OSDI scores from 60.02 (± 14.2) to 36.02 (± 20.70) (p=0.01), and conjunctival hyperemia from 1.33 (± 0.68) to 0.94 (± 0.87) (p=0.048). All the other evaluated outcomes only showed significant differences in the sirolimus group: corneal/conjunctival staining score (p=0.0015), lipid layer interferometry (p=0.006), and inferior meibomian gland dropout (p=0.038). No local or systemic adverse effects regarding the medication itself were reported, and the administration route was well accepted. Conclusion: Our findings suggest that sub-conjunctival sirolimus-loaded liposomes are effective in reducing both signs and symptoms of dry eye in patients with poorly controlled moderate-to-severe DED, while avoiding other topical administration adverse effects. Further investigation with a larger sample size is required to determine long-term effects.

Intravitreal bromfenac liposomal suspension (100 µg / 0.1 ml). A safety study in rabbit eyes.

INTRODUCTION: There is a need to find alternative treatments for MEe. Bromfenac has shown promise in inhibiting the COX-2 enzymatic pathway that partially causes the inflammatory cascade which contributes to the precipitation of ME. However, like other NSAID's, its intraocular half-life is limited. We hypothesize that a delayed-release liposome formulation containing bromfenac might provide a similar anti-inflammatory effect as long-lasting steroid release systems without the well-known steroidal side-effects. We introduced a novel formulation with these characteristics into the vitreous cavity of rabbit eyes in order to evaluate its safety profile. MATERIAL AND METHODS: 10 left eyes of rabbits were injected with the liposome-encapsulated bromfenac suspension (100 µg/0.1 ml). Basal ERG's were recorded. Total follow-up time was 3 months, at which point ERG's were repeated and eyes were enucleated for histopathological study. Total amplitude and implicit times were recorded. A difference of 25% in either recording was considered significant. Significance was assessed using the paired-t test and Wilcoxon matched-pairs signed-rank test. A p-value of <0.05 was considered significant. RESULTS: No significant changes were recorded in ERG measurements after 3 months when compared to basal measurements. Histopathological analysis of retinal specimens found no traces of liposome-induced toxicity. CONCLUSION: The liposome-encapsulated bromfenac suspension (100 µg/0.1 ml) is not toxic and has been proven safe to use in an animal model. Therefore, this formulation shows promise as a possible future alternative treatment for ME and should be further studied to show its biological effect and efficacy.

Retrograde axonal transport obstruction of brain-derived neurotrophic factor (BDNF) and its TrkB receptor in the retina and optic nerve of American Cocker Spaniel dogs with spontaneous glaucoma.

OBJECTIVE: To determine the degree of retrograde optic nerve axonal transport obstruction at the scleral lamina cribosa level by examining levels of brain-derived neurotrophic factor (BDNF) and its tyrosine kinase receptor type B (TrkB) in dogs presenting with high intraocular pressure. ANIMALS STUDIED: A total of 10 eyes, four normal and six glaucomatous eyes, from normal and affected American Cocker Spaniels with primary glaucoma were studied. All eyes were assessed by neuro-ophthalmic examination, tonometry, gonioscopy, slit-lamp biomicroscopy, and indirect ophthalmoscopy prior to enucleation. METHODS: Immunocytochemistry analysis was performed to evaluate BDNF and TrkB receptor expression in retina and optic nerve in normal and glaucomatous dogs. RESULTS: In all normal eyes BDNF immunostaining was detected in the cytoplasm of retinal ganglion cells (RGC), inner plexiform layer (IPL), inner nuclear layer (INL), nerve fiber layer (NFL), optic nerve head cells, and lamina cribosa cells. In all glaucomatous eyes BDNF was more evident in RGC, NFL and lamina cribosa cells. TrkB receptor was detected in the cytoplasm of RGC, NFL and ONH bundles in all normal eyes, and in a more intense pattern in all glaucomatous eyes. CONCLUSIONS: BDNF retrograde axonal transport is substantially inhibited by intraocular pressure elevation. TrkB accumulation at the ONH in glaucoma suggests a role for neurotrophin deprivation in the pathogenesis of RGC death in canine glaucoma, as well as a possible paracrine and/or autocrine signaling within the lamina cribosa. Neurotrophin signaling may regulate more than neuronal development, survival and differentiation. BDNF neurotrophin and its TrkB receptor expression by lamina cribosa cells and ONH astrocytes in glaucomatous eyes may help to determine the role of these cells as a paracrine source in terms of retinal ganglion cell survival, during episodes of elevated intraocular pressure.

Endothelin-1, nitric oxide, and glutamate in the normal and glaucomatous dog eye.

PURPOSE: To document differences in the levels of the endothelin-1 peptide, nitric oxide, and glutamate in aqueous humor and vitreous in the dog eye with spontaneous glaucoma compared to the normal dog eye. METHODS: Samples of aqueous humor and vitreous from enucleated normal eyes (n = 21) of 14 dogs and glaucomatous eyes (n = 8) of eight dogs were collected. Levels of endothelin-1, nitric oxide, and glutamate were measured by enzyme immunoassay. RESULTS: Endothelin-1 aqueous humor levels (mean +/- SD) increased significantly from 3.05 (+/- 1.66) pg/mL for the normal eyes to 6.22 (+/- 2.83) pg/mL for the glaucomatous eyes (P = 0.0054). The increase in vitreous from 1.83 (+/- 1.66) pg/mL for the normal eyes to 2.86 (+/- 1.31) pg/mL for the glaucomatous eyes was not significant (P = 0.0840). Nitric oxide levels (mean +/- SD) increased significantly in aqueous humor from 4.12 (+/- 2.64) microM for the normal eyes to 12.95 (+/- 14.42) microM for the glaucomatous eyes (P = 0.0141). The vitreous levels increased from 4.86 (+/- 3.92) microM for the normal eyes to 15.33 (+/- 16.22) microM for the glaucomatous eyes (P = 0.0179). Glutamate levels (mean +/- SD) decreased nonsignificantly in aqueous humor from 2.35 (+/- 3.84) microM for the normal eyes to 1.61 (+/- 0.74) microM for the glaucomatous eyes (P = 0.9377) and in vitreous from 1.37 (+/- 1.89) microM for the normal eyes to 1.02 (+/- 1.11) microM for the glaucomatous eyes (P = 0.3303). CONCLUSION: Endothelin-1 and nitric oxide increased in aqueous humor and vitreous of dogs with spontaneous glaucoma while the changes in glutamate varied.

Measurement of retinal nerve fiber layer thickness in normal and glaucomatous Cocker Spaniels by scanning laser polarimetry.

OBJECTIVE: To measure changes in the thickness of the retinal nerve fiber layer in normal and early glaucomatous dogs with scanning laser polarimetry. ANIMALS STUDIED: A total of 45 eyes, 32 normal and 13 glaucomatous eyes, of American Cocker Spaniels with primary glaucoma were used. All eyes were evaluated through a complete neuro-ophthalmic examination, tonometry, gonioscopy, slit-lamp biomicroscopy, and indirect ophthalmoscopy prior to enucleation. METHODS: The retinal nerve fiber layer thickness was measured in anesthetized animals with scanning laser polarimetry (Nerve fiber analyzer, GDx; Laser Diagnostic Technologies, LTD, San Diego, CA, USA). Glaucomatous eyes retained some vision at the time of this study. RESULTS: The mean +/- SD of the retinal nerve fiber layer thickness was 141.69 +/- 18 microm for normal dogs and 105.08 +/- 23.86 microm for visual glaucomatous dogs. The average retinal nerve fiber layer thickness in the superior and inferior retinal quadrants was 148.03 +/- 8.5 and 141.06 +/- 8.73 microm, respectively, for normal dogs, and 106.61 +/- 25.77 and 107.08 +/- 24.99 microm in the superior and inferior retinal quadrants, respectively, for glaucomatous dogs. The superior to nasal retinal nerve fiber layer thickness ratio was 1.45 for normal dogs and 1.26 for visual glaucomatous dogs. CONCLUSIONS: Using scanning laser polarimetry it was possible to detect changes in retinal nerve fiber layer thickness in glaucomatous dogs at early stages of the disease. Therefore, this instrument has the potential to improve the clinical management of canine glaucoma by detecting progressive changes to the retinal nerve fiber layer.

Endothelin 1 levels in the aqueous humor of dogs with glaucoma.

PURPOSE: Endothelin 1 is a small peptide that is involved in regulation of intraocular pressure and modulation of ocular circulation. To investigate the role of endothelin 1 in canine glaucoma, the authors measured aqueous humor levels of endothelin 1 in healthy dogs and in dogs with hypertensive glaucoma. METHODS: Aqueous humor samples were obtained with general anesthesia from the eyes of healthy dogs (n = 5) and dogs with hypertensive glaucoma (n = 10). Measurements were made by enzyme immunoassay for endothelin 1. RESULTS: The endothelin 1 aqueous humor range was 1.12 - 3.63 pg/mL for healthy dogs and 1.97 - 14.97 pg/mL for glaucomatous dogs. The healthy and glaucomatous canine endothelin 1 aqueous levels (mean +/- SD) were 2.33 +/- 0.90 and 8.11 +/- 5.03 pg/mL, respectively. A two-way analysis of variance indicated that this difference was significant (P = 0.0084). The effect of age on endothelin 1 levels was not significant (P = 0.6283). The large variability found within the glaucomatous group could be explained by the degree of damage of the retina (P = 0.0006). There was no significant correlation between intraocular pressure and endothelin 1 aqueous humor levels within the glaucomatous group (P = 0.29). CONCLUSIONS: The aqueous humor of dogs with hypertensive glaucoma contains significantly higher levels of endothelin 1 than that of healthy dogs.