The short-needle intravitreal injection technique

Effect of twisting of intravitreal injections on ocular bio-mechanics: a novel insight to ocular surgery

Although intravitreal (IVT) injections provide several advantages in treating posterior segment eye diseases, several associated challenges remain. The current study uses the finite element method (FEM) to highlight the effect of IVT needle rotation along the insertion axis on the reaction forces and deformation inside the eye. A comparison of the reaction forces at the eye's key locations has been made with and without rotation. In addition, a sensitivity analysis of various parameters, such as the needle's angular speed, insertion location, angle, gauge, shape, and intraocular pressure (IOP), has been carried out to delineate the individual parameter's effect on reaction forces during rotation. Results demonstrate that twisting the needle significantly reduces the reaction forces at the penetration location and throughout the needle travel length, resulting in quicker penetration. Moreover, ocular biomechanics are influenced by needle insertion location, angle, shape, size, and IOP. The reaction forces incurred by the patient may be reduced by using a bevel needle of the higher gauge when inserted close to the normal of the local scleral surface toward the orra serrata within the Pars Plana region. Results obtained from the current study can deepen the understanding of the twisting needle's interaction with the ocular tissue.

Novel Drug Delivery Systems Fighting Glaucoma: Formulation Obstacles and Solutions

Glaucoma is considered to be one of the biggest health problems in the world. It is the main cause of preventable blindness due to its asymptomatic nature in the early stages on the one hand and patients' non-adherence on the other. There are several approaches in glaucoma treatment, whereby this has to be individually designed for each patient. The first-line treatment is medication therapy. However, taking into account numerous disadvantages of conventional ophthalmic dosage forms, intensive work has been carried out on the development of novel drug delivery systems for glaucoma. This review aims to provide an overview of formulation solutions and strategies in the development of in situ gel systems, nanosystems, ocular inserts, contact lenses, collagen corneal shields, ocular implants, microneedles, and iontophoretic devices. The results of studies confirming the effectiveness of the aforementioned drug delivery systems were also briefly presented.

Efficacy and safety of intravitreal drug injections using a short 34-gauge needle

PURPOSE

To evaluate the efficacy and safety of intravitreal drug injections using a short 34-gauge needle.

STUDY DESIGN

Retrospective study.

METHODS

This study included patients with age-related macular degeneration, diabetic macular edema, or macular edema associated with retinal vein occlusion. We reviewed the medical records of consecutive patients with one of those three diseases treated with antivascular endothelial growth factor (VEGF) agents using an 8-mm-long 34-gauge needle. Sustained intraocular pressure (IOP) elevations were defined as IOP exceeding 21 mmHg or 6-mmHg or higher increases from baseline on 2 consecutive visits at least 1 month apart. The main outcome measures were improved best-corrected visual acuity (BCVA), central retinal thickness (CRT), IOP changes, and incidence of complications related to the 34-gauge needle.

RESULTS

Six hundred ninety-eight injections were administered to 243 consecutive patients (mean age, 74.0 years) and reviewed. The mean follow-up time was 30.2 ± 15.9 weeks. The mean number of intravitreal injections/eye was 2.7 ± 1.8 (range, 1-9). The mean BCVA improved significantly (P < .0001), from 0.43 ± 0.4 logarithm of the minimum angle of resolution (logMAR) units at baseline to 0.36 ± 0.41 logMAR units at the last visit. The mean CRT decreased significantly (P < .0001), from 426.9 ± 168.5 microns at baseline to 297.6 ± 121.1 microns at the last visit. The mean IOP decreased significantly (P < .0001), from 13.6 ± 3.0 mmHg at baseline to 12.9 ± 3.1 mmHg at the visit after the first injection. A retinal tear occurred in 0.14%/injection (1/698). A sustained IOP elevation occurred in 1.29%/injection (9/698).

CONCLUSION

Despite a few complications, the short 34-gauge needle was efficacious and safe for anti-VEGF intravitreal injections.