Safety of intravitreal triamcinolone and its impact on optic nerve morphology in patients treated for diabetic macular edema

PURPOSE

To assess the impact of one intravitreal injection (IVT) of Triamcinolone Acetonide (TA) on intraocular pressure (IOP) and optic nerve structural parameters in patients treated for Diabetic Macular Edema (DME).

METHODS

This retrospective study included patients with DME that were naïve to intraocular steroids and underwent one IVT of TA of 4 mg/0.1 mL and age-matched controls with DME without criteria for IVT. Patients records were reviewed for IOP (at baseline and a month after IVT) and optic nerve parameters measured by optical coherence tomography (up to 6 months before and 6 months after IVT). Exclusion criteria included glaucoma and treatment with hypotensive agents.

RESULTS

Twenty-six eyes were included in the Control Group and 29 in the IVT Group, with a mean age of 65.10 ± 10.08 and 67.30 ± 4.71 years, respectively (p = 0.06). At baseline, IOP and optic nerve measurements were equivalent between groups (p > 0.05). One month after IVT, mean IOP measurements in IVT Group were higher than those of controls (17.84 ± 4.50 vs 11.59 ± 3.09 mmHg, p < 0.001). Ocular hypertension (OHT) developed in 17.24% of cases and reversed with topical medication. After one IVT, vertical cup/disc ratio was higher (0.57 ± 0.25 vs 0.60 ± 0.14, p = 0.04) and retinal nerve fiber layer thickness was globally lower (mean: 91.03 ± 4.25 vs 81.33 ± 19.10 µm, p = 0.001) in the IVT Group.

CONCLUSION

Our results confirmed that intravitreal TA results in IOP increase. This seems to negatively affect optic nerve morphology, even in patients without OHT or adequately treated with hypotensive agents.

Micelle formulation of hexadecyloxypropyl-cidofovir (HDP-CDV) as an intravitreal long-lasting delivery system

There still is an unmet need for a safe and sustained intravitreal drug delivery system. In this study we are proposing and characterizing a micelle based, clear-media intravitreal drug delivery system using the lipid derivatized nucleoside analog, hexadecyloxypropyl-cidofovir (HDP-CDV, CMX 001). HDP-CDV forms micelles in water and in vitreous supernatant with the critical micelle concentration of 19 μg/mL and 9 μg/mL, respectively at 37 °C. The formed micelles had the average size of 274.7 nm and the Zeta potential of -47.1 mV. Drug release study in the excised rabbit vitreous showed a sustained release profile with a half-life of 2.7 days. The micelle formulation of HDP-CDV demonstrated a good safety profile in two animal species (rabbit and guinea pig) following intravitreal injection. The sustained efficacy was tested in a pretreatment study design and the drug potency was tested in an ongoing herpes simplex virus (HSV-1) retinitis model. The pretreatment studies using single intravitreal injection and later HSV-1 infection revealed at least 9 weeks of vitreous presence and therapeutic level of HDP-CDV, with 71% eyes protection from infection. The treatment study demonstrated that intravitreal administration halted active HSV-1 retinitis in 80% of the infected eyes while cidofovir (CDV) treatment failed to suppress active HSV-1 retinitis. In summary, lipid derivatized nucleoside analogs can be formulated as a micelle intravitreal injection and provides a sustained drug release in vitreous for chronic retinal diseases.

Pars plana vitrectomy with internal limiting membrane peeling for diabetic macular edema

PURPOSE

To evaluate anatomic and visual acuity (VA) results of pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling for diffuse diabetic macular edema (DME), and to review the literature on the topic.

METHODS

Retrospective noncomparative case series of patients who underwent PPV with ILM peeling for diffuse DME between January 1, 2000, and December 1, 2005, performed by three surgeons at Bascom Palmer Eye Institute. Main outcome measures included pre- and postoperative optical coherence tomography (OCT) and visual acuity. Mean follow-up period was 8 months (range, 43 days-2 years).

RESULTS

Twenty-four eyes of 23 patients meeting the criteria were evaluated. Duration of DME ranged from 1 to 93 months. Mean preoperative logMAR vision was 0.782 (range, 0.30-1.82). Mean logMAR visual acuity at final follow-up was 0.771 (range, 0.10-2.00). At last follow-up, 25% of eyes had > or =2 line increase in VA from baseline, 54% of eyes had no improvement in VA, and 21% of eyes had > or =2 line decrease in VA. Of 9 eyes with pre- and postoperative OCT, there was an overall reduction in central macular thickness of 141 microm at postoperative month 3 and 120 microm at last follow-up. Postoperative complications included progression of cataract in 6 (60%) of 10 phakic eyes, postoperative intraocular pressure > or =30 mmHg in 6 (24%) eyes, and postoperative vitreous hemorrhage in 2 (8%) eyes.

CONCLUSIONS

Pars plana vitrectomy with ILM peeling was associated with a reduction in DME when measured by OCT in the majority of eyes, but visual acuity outcomes showed minimal improvement compared to baseline. These results suggest the efficacy of PPV with ILM peeling for eyes with DME has not been well established and should be reserved for therapy with selected cases.