Effects of subconjunctival methylprednisolone on the blood aqueous barrier following cataract surgery

Factors influencing aqueous flare after cataract surgery and its evaluation with laser flare photometry

Despite the refinement of modern cataract surgery, postoperative inflammation still constitutes a substantial amount of visual morbidity worldwide. A surrogate for intraocular inflammation and blood-aqueous barrier breakdown can be objectively quantified by Laser flare photometry (LFP). This review outlines the utility of LFP in assessing the assessment of post-cataract surgery inflammation. It highlights the impact of preoperative pathological states such as uveitis and diabetes, intraoperative techniques, including efficient phacoemulsification and direct comparisons between postoperative anti-inflammatory regimes. There is a large interobserver variation in the subjective flare measurement after cataract surgery and the continued use of LFP amongst other objective, noninvasive measurements of intraocular inflammation, particularly in the further development of cataract surgery, is recommended.

Laser flare-cell photometer: principle and significance in clinical and basic ophthalmology

A slit-lamp examination is an indispensable and essential clinical evaluation method in ophthalmology, but, it is qualitative subjective. To complement its weaknesses in making a quantitative evaluation of flare intensity and number of cells in the aqueous humor in the eye, we invented the laser flare-cell photometer in 1988. The instrument enables a non-invasive quantitative evaluation of flare intensity and number of cells in the aqueous with good accuracy and repeatability as well as maneuverability equal to slit-lamp microscopy. The instrument can elucidate the pathophysiology in the blood-aqueous barrier (BAB) function in a variety of ocular disorders. The accuracy of the instrument makes it possible to investigate not only the pathophysiology of intraocular disorders but also the effects of various drugs and surgical procedures in BAB. The instrument does not only lighten the burden on patients in clinical examinations and study but it also helps minimize the sacrifice of experimental animals and improves the reliability of the results by minimizing inter-individual variations through its good repeatability. Here I shall relate how the instrument has been applied to clinical and basic studies in ophthalmology and what novel knowledge its application contributed to pathophysiology in ophthalmology.

Comparison of peroperative subconjunctival injection of methylprednisolone and standard postoperative steroid drops after uneventful cataract surgery

PURPOSE

To compare the safety and efficacy of a single subconjunctival injection of methylprednisolone and a standard postoperative steroid regimen in terms of intraocular inflammation and intraocular pressure (IOP) after uncomplicated phacoemulsification surgery.

METHODS

Two groups of 25 patients each were included in this prospective randomized controlled trial. Patients in the injection group were given a subconjunctival injection of 20 mg methylprednisolone and the topical group received the conventional postoperative care with steroid eye drops (dexamethasone 1 mg/ml). The patients were examined 1 week and 1 month after surgery. Slit-lamp evaluation of anterior chamber inflammation and IOP were performed. Changes in IOP of ≥2.4 mmHg were considered clinically relevant.

RESULTS

In the injection group, mean IOP decreased from 15.4 ± 2.2 mmHg (baseline) to 14.1 ± 3.2 mmHg at 1 week (p = 0.03). The topical group had a stable IOP at 1 week (16.3 ± 2.6 mmHg) compared to baseline (16.1 ± 2.7 mmHg; p = 0.74). At 1 month, mean IOP was 14.3 ± 2.6 mmHg (p = 0.03) in the injection group and 15.6 ± 2.3 mmHg (p = 0.2) in the topical group. The intragroup changes were neither statistically significant nor clinically relevant at any postoperative visit. Both groups had the highest values of intraocular inflammation at the 1-week postoperative visit, followed by a decline to barely traceable levels at 1 month. The difference was not clinically relevant at any postoperative visit.

CONCLUSIONS

The subconjunctival injection of methylprednisolone appears to be as safe and effective as the conventional treatment, and it might therefore be considered for treatment of individuals with compliance issues.

Inhibition of Endotoxin-Induced Uveitis by Methylprednisolone Acetate Nanosuspension in Rabbits

PURPOSE

In this study, nanoformulations of methylprednisolone acetate (MPA) were formulated by using a copolymer of poly(ethylacrylate, methyl-methacrylate and chlorotrimethyl-ammonioethyl methacrylate) to study their impacts on the inhibition of inflammatory symptoms in rabbits with endotoxin-induced uveitis (EIU).

METHODS

A modified quasiemulsion solvent diffusion technique was used for the preparation of the nanoparticles. The drug-release profiles and physicochemical characteristics of the nanoformulations were studied by means of X-ray crystallography, differential scanning calorimetry, and Fourier transform infrared spectroscopy. Particle-size analysis yielded mean diameters of approximately 380, 460, and 580 (nm) for copolymer nanoparticles at the ratios of 1:2.5, 1:5, and 1:10, respectively. Major clinical symptoms of EIU (e.g., morphologic changes, leukocytes numbers, and protein levels within the aqueous humor) were examined.

RESULTS

Upon the physicochemical characterizations, no crystal changes or chemical interactions were observed for the copolymer nanoparticles. The 1:2.5 ratio of drug polymer resulted in the most controlled release of MPA. The in vivo examinations revealed that the endotoxin-induced inflammation can be inhibited by the copolymer nanosuspension more significantly than by the microsuspension of MPA itself in the rabbits with EIU.

CONCLUSIONS

Based on our findings, we suggest that the copolymer nanosuspension may favor the localized, controlled ocular delivery of MPA for the prevention of inflammatory symptoms in ocular diseases.