Effect of posterior juxtascleral triamcinolone acetonide on the efficacy and choriocapillaris hypoperfusion of photodynamic therapy

Drug Delivery to the Posterior Segment of the Eye: Biopharmaceutic and Pharmacokinetic Considerations

The treatment of the posterior-segment ocular diseases, such as age-related eye diseases (AMD) or diabetic retinopathy (DR), present a challenge for ophthalmologists due to the complex anatomy and physiology of the eye. This specialized organ is composed of various static and dynamic barriers that restrict drug delivery into the target site of action. Despite numerous efforts, effective intraocular drug delivery remains unresolved and, therefore, it is highly desirable to improve the current treatments of diseases affecting the posterior cavity. This review article gives an overview of pharmacokinetic and biopharmaceutics aspects for the most commonly-used ocular administration routes (intravitreal, topical, systemic, and periocular), including information of the absorption, distribution, and elimination, as well as the benefits and limitations of each one. This article also encompasses different conventional and novel drug delivery systems designed and developed to improve drug pharmacokinetics intended for the posterior ocular segment treatment.

Photodynamic Therapy and Intravitreal Bevacizumab with Versus without Triamcinolone for Neovascular Age-related Macular Degeneration; a Randomized Clinical Trial

PURPOSE

To compare the outcomes of photodynamic therapy (PDT) combined with intravitreal bevacizumab (IVB) with versus without intravitreal triamcinolone (IVT) in neovascular age-related macular degeneration (AMD).

METHODS

Eighty-four eyes with active CNV secondary to AMD with no prior treatment were enrolled and followed for 1-year. Eligible eyes were randomly assigned to either PDT/IVB or PDT/IVB/IVT. The main outcome measure was change in best-corrected visual acuity (BCVA).

RESULTS

Mean patient age was 71 ± 9 years. BCVA changes from baseline were statistically significant in both study arms at all follow-up intervals, however no significant difference was observed between the two groups regarding BCVA changes at week 12 (95% CI:-0.11-0.12 LogMAR) and other time points (all P > 0.6). Mixed model analysis revealed a significant effect from age (P < 0.001), pigment epithelial detachment (P = 0.009) and baseline BCVA (P < 0.001) on visual improvement. Significant central macular thickness (CMT) reduction occurred at all-time points as compared to baseline in both groups which was comparable between the study arms. There was no significant difference between the study arms in terms of retreatment rate (P = 0.1) and survival to the first repeat IVB injection (P = 0.065).

CONCLUSION

Additional low-dose IVT to a PDT/IVB regimen for neovascular AMD provided no beneficial effects in terms BCVA or CMT, yet demonstrated a trend toward extending the injection-free period.

Choroidal infarction after photodynamic therapy combined with bevacizumab and triamcinolone reversed by tissue plasminogen activator: case report

PURPOSE

To present a case of choroidal infarction after combined therapy of photodynamic therapy, intravitreal bevacizumab, and sub-Tenon triamcinolone injection salvaged by tissue plasminogen activator administration.

METHODS

Interventional case report.

RESULTS

Combined therapy of full-fluence photodynamic therapy, intravitreal bevacizumab, and sub-Tenon triamcinolone injection was given on the same day to treat neovascular age-related macular degeneration in an 82-year-old patient. Subsequent acute visual loss and marked macular edema as a result of choroidal infarction were noted. Intravitreal and sub-Tenon administration of tissue plasminogen activator were performed 9 days later to salvage the choroidal infarction, and visual improvement was noted. Fundoscopy and optical coherent tomography showed almost complete resolution of macular edema. Indocyanine green angiography revealed reperfusion of the choroidal vessels.

CONCLUSION

Choroidal infarction may happen after combined therapy. Tissue plasminogen activator administration may reverse the infarction and help visual recovery.

One-year results of photodynamic therapy combined with intravitreal ranibizumab for exudative age-related macular degeneration

Purpose. To evaluate the effects of photodynamic therapy (PDT) combined with intravitreal injection of ranibizumab (IVR) for exudative age-related macular degeneration (AMD). Methods. Retrospective case series. Thirty eight eyes of 38 patients with exudative AMD underwent combined therapy consisting first of IVR, followed by PDT within a week and the second IVR at 1 month. All patients were followed up for more than 12 months. The best corrected visual acuity (BCVA) and central macular thickness (CMT) were examined. Results. The mean number of IVR and PDT sessions were 2.9 ± 1.3 and 1.1 ± 0.3, respectively. The mean BCVA and CMT were significantly improved to 0.38 logMAR units (P < 0.01) and 240 μm (P < 0.01) at 12 months, respectively. Thirty-six of 38 eyes (94.8%) improved or maintained BCVA at 12 months. Conclusion. PDT combined with IVR for exudative AMD was effective at improving visual acuity and CMT with a low recurrence rate for 12 months.

Effect of photodynamic therapy alone or combined with posterior subtenon triamcinolone acetonide or intravitreal bevacizumab on choroidal hypofluorescence by indocyanine green angiography

PURPOSE

Choroidal hypofluorescence has been reported beneath the photodynamic therapy (PDT) site in clinical studies. We evaluated the choroidal hypofluorescence after combined PDT with posterior subtenon injection of triamcinolone acetonide or PDT with an intravitreal injection of bevacizumab for age-related macular degeneration.

METHODS

Two hundred and forty-two eyes with a subfoveal choroidal neovascularization caused by age-related macular degeneration were studied. Ninety-two eyes underwent PDT alone, 90 eyes underwent PDT with sub-Tenon injection of triamcinolone acetonide, and 60 eyes underwent PDT with intravitreal injection of bevacizumab. Verteporfin-induced choroidal hypoperfusion was determined by indocyanine green angiograms. The intensity of the diffuse fluorescence within the PDT site away from the choroidal neovascularization lesion and from the normal retina just peripheral to the optic disk was measured by densitometry (Topcon IMAGEnet computer system, Topcon, Tokyo, Japan) in the indocyanine green angiogram images obtained at 10 minutes 3 months after the PDT. The ratio of the average brightness of the retina within the PDT area to that of the retina peripheral to the optic disk (irradiated/nonirradiated retinal brightness ratio) was calculated for each angiogram.

RESULTS

The irradiated/nonirradiated retinal brightness ratio of the angiograms was 0.96 in the PDT-alone group, 0.85 in the sub-Tenon injection of triamcinolone acetonide-PDT group, and 0.89 in the intravitreal injection of bevacizumab-PDT group (Kruskal-Wallis H test, P < 0.05).

CONCLUSION

The degree of choroidal hypofluorescence in the indocyanine green angiogram images 3 months after PDT in the sub-Tenon injection of triamcinolone acetonide and intravitreal injection of bevacizumab group was higher than that of PDT-alone group. Sub-Tenon injection of triamcinolone acetonide and intravitreal injection of bevacizumab can prolong the duration of the choroidal hypofluorescence after PDT.

Focal macular electroretinograms after photodynamic therapy combined with posterior juxtascleral triamcinolone acetonide

PURPOSE

Retinal function is commonly depressed transiently after photodynamic therapy (PDT). Additional treatment may prevent this impaired retinal function. The purpose of this study was to determine the changes in the focal macular electroretinograms (FMERGs) after PDT combined with TA for age-related macular degeneration.

METHODS

Thirty-four eyes that were successfully treated by PDT with a posterior juxtascleral injection of TA were studied. FMERGs, optical coherence tomography, and indocyanine green angiography were performed before and after the PDT.

RESULTS

The mean amplitudes of the FMERGs were not significantly decreased 1 week after PDT with TA (P > 0.05). The mean ratio of the FMERG b-wave 1 week after PDT to that before PDT was 1.09, with an indistinct hypofluorescence at the site of the PDT (18 eyes), and the ratio was 0.91 in the eyes with a distinct hypofluorescence border (16 eyes; P < 0.05).

CONCLUSION

The combined use of TA with PDT mitigated the depression of retinal function soon after PDT. However, there were cases of severe choroidal hypoperfusion corresponding to the site of the laser spot that impaired retinal function in comparison to cases with mild hypoperfusion. Even with severe choroidal hypoperfusion, the deterioration in retinal function was relatively mild, with the b-wave FMERG reduced by only 10%.

Inhibition of proliferation, migration and tube formation of choroidal microvascular endothelial cells by targeting HIF-1alpha with short hairpin RNA-expressing plasmid DNA in human RPE cells in a coculture system

BACKGROUND

Retinal pigment epithelial (RPE) cells and choroidal microvascular endothelial cells (CECs) are the main cells involved in choroidal neovascularization (CNV), and hypoxia plays an important role in CNV formation via hypoxia inducible factor 1 (HIF-1). Our aim was to evaluate the role of HIF-1 in human RPE cells with regard to proliferation, migration and tube formation of CECs under hypoxia.

METHODS

RPE cells were cultured under chemical hypoxia induced by 200 muM CoCl(2), and RNA interference (RNAi) technique was used to knock down HIF-1alpha gene in RPE cells. mRNA and protein expression of HIF-1alpha and VEGF in RPE cells were investigated by real-time RT-PCR and Western blot. Three kinds of coculture models were used to observe the effects of RPE cells transfected by short hairpin RNA (shRNA)-expressing plasmid DNA (pDNA) (pshHIF-1alpha) on the proliferation, migration and tube formation of CECs respectively.

RESULTS

Transfection of shRNA-expressing pDNA targeting HIF-1alpha to RPE cells resulted in the knock down of HIF-1alpha gene and reduction of the corresponding mRNA and protein of HIF-1alpha and VEGF under hypoxia. Consequently, the proliferation, migration and tube formation of CECs were significantly inhibited by the knocked-down RPE cells compared with the control in the coculture system. The proliferation rates of CECs decreased by 40.2%, 36.6% and 36.8% on days 3, 4 and 5 respectively. Migration reduced by 49.6% at 5 h, and tube formation decreased by 40.4% at 48 h.

CONCLUSION

RNAi of HIF-1alpha in RPE cells can inhibit angiogenesis in vitro and provide a possible strategy for treatment of choroidal neovascularization diseases by targeting HIF-1alpha.