Intravitreal pharmacokinetics after posterior subtenon triamcinolone acetonide injection in vitrectomized rabbit eyes

Comparison of intravitreal preservative-free triamcinolone versus posterior sub-tenon triamcinolone acetonide injection for bevacizumab-resistant diabetic macular edema

BACKGROUND

Triamcinolone acetonide (TA) is administered as an intravitreal or posterior sub-Tenon's capsule injection, as treatment for diabetic macular edema (DME). The intravitreal use of TA is limited because commercially available triamcinolone acetonide contains benzyl alcohol, a neurotoxic preservative. Few studies have compared effects of preservative-free intravitreal TA (IVTA) and posterior sub-Tenon capsule TA (STTA) injections for DME. Thus, herein, we compared the effectiveness of preservative-free IVTA and STTA for treatment of bevacizumab-resistant DME.

METHODS

In this retrospective cohort study, bevacizumab-resistant DME was defined as a lack of response to at least three consecutive intravitreal bevacizumab (IVB) injections. Changes in mean central macula thickness (CMT), best-corrected visual acuity (BCVA), and intraocular pressure (IOP) between IVTA and STTA groups were compared at baseline and at 1, 2, and 3 months after treatment.

RESULTS

Forty eyes from 40 patients were included in this study. In the IVTA group, the mean CMT improved significantly from 400.2 ± 144.42 μm at baseline to 288.35 ± 151.74 μm at 3 months after treatment (p = 0.01). Similarly, in the STTA group, the mean CMT improved significantly from 446.65 ± 120.74 μm at baseline to 382.9 ± 113.58 μm at 3 months after treatment (p = 0.009). The mean BCVA of the IVTA group also showed improvement, decreasing from 0.75 ± 0.55 logarithm of the minimum angle of resolution (logMAR) at baseline to 0.625 ± 0.50 logMAR at 3 months after treatment (p = 0.089). Similarly, the mean BCVA of the STTA group improved, from 0.6 ± 0.36 logMAR at baseline to 0.54 ± 0.35 logMAR at 3 months after treatment (p = 0.094).

CONCLUSION

Given that IVTA and STTA demonstrated statistically equivalent anatomical and functional effects in patients with bevacizumab-resistant DME, the less invasive STTA may be considered the preferred treatment approach for the management of bevacizumab-resistant DME.

TRIAL REGISTRATION

Retrospectively registered.

Pharmacokinetics after Periocular Methylprednisolone Sodium Succinate Injection in Rabbit Eyes

The present study aimed to determine the pharmacokinetics and distribution of methylprednisolone sodium succinate (MPSS) and its metabolic product methylprednisolone (MP) in plasma and ocular tissues after periocular injection of MPSS in rabbit eyes. Forty-eight healthy New Zealand white rabbits were randomly divided into 12 groups, including the control group and 11 MPSS-treated groups sampling at different time points. Rabbits in the MPSS-treated groups underwent left eye periocular injection of MPSS (10 mg). The pharmacokinetics of MPSS and MP in plasma and ocular tissues (including aqueous humor, vitreous, iris, lens, sclera, optic nerve, and choroid and retina) were investigated by liquid chromatography tandem mass spectrometry (LC-MS/MS). After periocular injection, the time of maximum concentration (T_max) of MPSS ranged from 0.25 h to 1 h in ocular tissues and was 0.25 h in plasma. T_max of MP in ocular tissues ranged from 0.5 h to 6 h, and T_max of MP in plasma was 0.5 h. The maximum concentration (C_max) of MPSS and MP and the area under the curve (AUC_0-t) in ocular tissues from high to low was sclera, optic nerve, choroid and retina, iris, and lens. Especially, the concentrations of MPSS and MP in the lens were much lower when compared with the other ocular tissues. After periocular administration, MPSS could be rapidly metabolized to its active constituent MP in the ocular tissues. Also, the MPSS can be delivered effectively into the posterior segment of the eye (choroid and retina), while not easily be absorbed by the lens.

Effectiveness of Intravitreal Dexamethasone Implant Treatment for Diabetic Macular Edema in Vitrectomized Eyes

Objectives:

To report the effectiveness and long-term outcomes of intravitreal dexamethasone implantation for diabetic macular edema (DME) in vitrectomized eyes

Materials and Methods:

Medical records of patients were retrospectively reviewed. Time of pars plana vitrectomy (PPV), PPV indications, interval between DEX injection and PPV, other intravitreal treatment prior to DEX application, best corrected visual acuity (BCVA), intraocular pressure (IOP), and central retinal thickness (CRT) measured by optical coherence tomography were recorded.

Results:

Seventeen eyes of 17 patients were included in the study. The mean follow-up after DEX injection was 21±2.4 months (12-43 months). The female/male ratio was 11/6. Mean age was 60.7 years (46-70 years). Sixteen eyes (94.1%) were pseudophakic at the time of DEX treatment. The most common indication for PPV was tractional retinal detachment (8 eyes, 47.1%). Ten eyes (58.8%) received a single injection and a total of 30 DEX implantations were performed. Mean BCVA was 0.77 logarithm of the minimum angle of resolution (logMAR) units before the first injection and improved to 0.64, 0.68 and 0.66 logMAR after 1, 3 and 6 months, respectively (p<0.01). CRT decreased significantly from 452 µm at baseline to 310, 368±34 and 375 µm after 1, 3 and 6 months, respectively (p<0.04). Mean IOP was 16±1.2 mmHg at baseline and 18.2, 18.8 and 18.5 mmHg after 1, 3, and 6 months (p>0.05). Two eyes (%8) received topical anti-glaucoma medication (IOP≥25 mmHg). Similar results were observed in eyes receiving repeated DEX injections.

Conclusion:

Intravitreal DEX injection treatment seems to be effective for improving BCVA and decreasing CRT in vitrectomized eyes with DME. This effect seemed to last for 6 months in most eyes, but maximized at 3 months. Patients with repeated injections often require injection before 6 months.

Comparison between intravitreal bevacizumab and posterior sub-tenon injection of triamcinolone acetonide in macular edema secondary to retinal vein occlusion

Aim

To compare the efficacy and safety between posterior sub-tenon injection of triamcinolone acetonide (PSTA) and intravitreal injection of bevacizumab (Avastin) (IVIA) in the treatment of macular edema secondary to retinal vein occlusion.

Patients and methods

A total of 45 eyes were retrospectively enrolled (23 eyes with intravitreal bevacizumab and 22 eyes with posterior sub-tenon triamcinolone acetonide). Main endpoints included logMAR of best-corrected visual acuity (BCVA), central macular thickness (CMT), and intraocular pressure (IOP) before and after treatment at 6 months.

Results

The mean logMAR improved from 0.78 to 0.56 at 6 months for intravitreal bevacizumab (p=0.001), and from 0.91 to 0.79 and 0.87 at 3 and 6 months (p=0.038 and 0.13), respectively, for sub-tenon triamcinolone acetonide. At 6 months, the BCVA was significantly better in the bevacizumab group (p=0.02). Both groups' mean CMT significantly improved, from 478 µm at baseline to 295 µm at 6 months in IVIA group (p<0.001) and from 419 µm at baseline to 350 µm in PSTA group (p=0.012); however, this was not different between the groups at 6 months (p=0.065). Recurrence of macular edema was not different between the groups either (p=0.08). Poorer final vision was associated with poorer baseline BCVA and diagnosis of central retinal vein occlusion after adjustment for age and sex (p<0.001 and 0.012, respectively). Significant elevation of IOP was noted at 3 months in the PSTA group, but declined at 6 months compared with baseline (p=0.002 and 0.41, respectively).

Conclusion

Intravitreal bevacizumab seemed to achieve better visual acuity compared with posterior sub-tenon injections of triamcinolone acetonide at 6 months, while CMT was comparable. PSTA still resulted in transient IOP elevation.

Comparison of vitrectomized with nonvitrectomized eyes after subtenon injection of triamcinolone acetonide to treat diabetic macular edema: Retrospective comparative Analysis of an interventional case series

PURPOSE

Triamcinolone acetonide (TA) is an alternative option for diabetic macular edema thanks to its cost-benefit ratio and unique delivery route. We performed this study to compare vitrectomized with nonvitrectomized eyes treated with subtenon TA injection for diabetic macular edema.

MATERIALS AND METHODS

We retrospectively reviewed the medical records of patients who had undergone subtenon TA injection for diabetic macular edema treatment. The patients were divided into two groups: Vitrectomized and nonvitrectomized. Visual acuity and central subfield macular thickness (CSMT) were analyzed before injection, at 1 and 3 months after injection.

RESULTS

Visual acuity in vitrectomized group improved significantly at 1 month (P = 0.002), but this improvement regressed after 3 months. In the nonvitrectomized group, visual acuity did not improve significantly after 1 month, but it did after 3 months (P = 0.019). The CSMT decreased significantly in both groups at 1 and 3 months (P < 0.001). There were no significant differences between the groups at either 1 or 3 months with regard to either visual improvement or change in CSMT.

CONCLUSION

Subtenon TA injection could be an alternative treatment option for diabetic macular edema, both in vitrectomized and in nonvitrectomized eyes. TA seems to take effect earlier and decay faster in vitrectomized eyes.

Effect of Posterior Subtenon Triamcinolone Acetonide Injection on Diabetic Macular Edema Refractory to Intravitreal Bevacizumab Injection

Purpose

To evaluate the effects of posterior subtenon triamcinolone acetonide injection on refractory diabetic macular edema (DME) after intravitreal bevacizumab (IVB) injection failure.

Methods

Patients with DME and central subfield thickness (CST) >300 µm who did not respond to IVB injections were retrospectively included. Specifically, we enrolled patients who were diagnosed with refractory DME and who experienced an increase in CST after 1 to 2 IVB injections or no decrease after ≥3 consecutive IVB injections. One clinician injected 20 mg of triamcinolone acetonide into the posterior subtenon space. All patients received ophthalmic examinations at baseline and at 2, 4, and 6 months post-baseline. Examinations included Snellen visual acuity, intraocular pressure, and spectral-domain optical coherence tomography.

Results

Forty eyes of 34 patients were included. The average baseline CST was 476 µm. The average CST decreased to 368 µm at 2 months, 374 µm at 4 months, and 427 µm at 6 months (p < 0.001 for all results, Wilcoxon signed-rank test). The average intraocular pressure increased from 15.50 to 16.92 mmHg at 2 months but decreased to 16.30 mmHg at 4 months and 15.65 mmHg at 6 months. Logarithm of the minimum angle of resolution visual acuity improved from 0.56 to 0.50 at 2 months (p = 0.023), 0.50 at 4 months (p = 0.083), and 0.48 at 6 months (p = 0.133, Wilcoxon signed-rank test). No complications were detected.

Conclusions

Posterior subtenon triamcinolone acetonide is an effective and safe treatment for reducing CST in DME refractory to IVB.