Macular atrophy after combined intravitreal triamcinolone and photodynamic therapy to treat choroidal neovascularization

Pharmacokinetics and retinal toxicity of various doses of intravitreal triamcinolone acetonide in rabbits

PURPOSE

To compare the pharmacokinetics and retinal toxicity of various doses of intravitreal triamcinolone acetonide (TA) in rabbits.

METHODS

The rabbits received intravitreal injections of 4 mg and 8 mg TA. The drug concentrations were determined with high-performance liquid chromatography after extraction from the vitreous at various time points. The main pharmacokinetics parameters were calculated with 3p97 pharmacokinetics software. The intraocular pressure, electroretinography, and pathological examinations were evaluated before and after intravitreal injection of different doses of TA.

RESULTS

The half-life of intravitreal injection of 4 mg and 8 mg TA was 24 days and 34 days, respectively. No significant differences were found in intraocular pressure (p>0.05) and the electroretinography b-wave amplitudes (p>0.05) among the rabbits before and after intravitreal injection of 4 mg and 8 mg TA. Light and electron microscopy did not show any retinal damage in any group.

CONCLUSIONS

Intravitreal injection of 4 mg and 8 mg TA are safe for the rabbit retina. The injection of 8 mg TA produced a longer vitreous half-life and had a prolonged effect on the retina. This conclusion may be referenced in the clinical application of TA in retinal diseases.

Initial non-responders to ranibizumab in the treatment of age-related macular degeneration (AMD)

BACKGROUND

Patients with exudative age-related macular degeneration (AMD) who did not respond to ranibizumab at the induction phase were assessed and referred to as initial non-responders.

METHODS

We retrospectively reviewed the medical records of 215 patients (218 eyes) with exudative AMD. For the initial treatments, patients received three intravitreal injections of ranibizumab (IVR) every 4 weeks. Minimum follow-up period was 12 months. We defined patients with no improvement of best corrected logMAR visual acuity (BCVA), and with no decrease of central retinal thickness (CRT) at the end of the initial treatment, as initial non-responders. Patients who had previous treatment history prior to this investigation were included, but patients who had photodynamic therapy (PDT) with IVR were excluded.

RESULTS

Twenty-two eyes (10.1%) were identified as initial non-responders. The mean BCVA of initial non-responders before IVR and after induction phase were 0.39 and 0.36, respectively. There was no significant difference between these values, however the mean BCVA decreased significantly to 0.55 at 12 months after the beginning of the induction phase (P = 0.021). The mean greatest linear dimension (GLD) of the lesion before IVR of initial non-responders was 4,121 μm. We found 16 eyes with typical AMD, and six eyes with polypoidal choroidal vasculopathy. One eye had predominantly classic choroidal neovascularization (CNV), and others had occult CNV of typical AMD. As additional treatments, twelve eyes received PDT, and in three of the eyes exudation remained after PDT.

CONCLUSION

Initial non-responders were more prevalent in patients with occult CNV than in patients with other CNV types. Some of the initial non-responders did not respond to PDT. This study suggested possible involvement of other factors, in addition to vascular endothelial growth factor, in the occurrence of CNV in initial non-responder patients.