Shear-Thinning Viscous Materials for Subconjunctival Injection of Microparticles.

While drug-loaded microparticles (MPs) can serve as drug reservoirs for sustained drug release and therapeutic effects, needle clogging by MPs poses a challenge for ocular drug delivery via injection. Two polymers commonly used in ophthalmic procedures-hyaluronic acid (HA) and methylcellulose (MC)-have been tested for their applicability for ocular injections. HA and MC were physically blended with sunitinib malate (SUN)-loaded PLGA MPs for subconjunctival (SCT) injection into rat eyes. The HA and MC viscous solutions facilitated injection through fine-gauged needles due to their shear-thinning properties as shown by rheological characterizations. The diffusion barrier presented by HA and MC reduced burst drug release and extended overall release from MPs. The significant level of MP retention in the conjunctiva tissue post-operation confirmed the minimal leakage of MPs following injection. The safety of HA and MC for ocular applications was demonstrated histologically.

Correction of axial length measurement error by IOLMaster 700 could improve refractive prediction accuracy in silicone oil-filled eyes.

PURPOSE: To determine whether correcting the axial length (AL) measurement error of the IOLMaster 700 could improve the refractive prediction accuracy in silicone oil-filled eyes. METHODS: This study included 265 cataract patients (265 eyes) with silicone oil tamponade who were scheduled for phacoemulsification with intraocular lens (IOL) implantation. The performances of various formulas, including Barrett Universal II, Emmetropia Verifying Optical, Hoffer-QST, Kane, Ladas Super Formula, Pearl-DGS, Radial Basis Function and traditional formulas (Haigis, Hoffer Q, Holladay 1 and SRK/T), were evaluated. The refractive prediction errors (PE) calculated with measured AL (ALmeas) and corrected AL with silicone oil adjustment (SOAL) were compared. Subgroup analysis was performed based on the ALmeas (<23 mm; 23-26 mm; ≥26 mm). RESULTS: Using SOAL significantly reduced the hyperopic PE of formulas when compared to ALmeas (-0.05 to 0.17 D vs 0.15 to 0.38 D, p < 0.001). After applying AL correction, all formulas showed a lower mean absolute PE (0.47-0.57 D vs 0.50-0.69 D). The percentage of eyes within ±1.0 D of PE increased from 84.91%-88.68% to 89.81%-91.32% for new formulas and from 78.11%-83.40% to 85.66%-88.68% for traditional formulas, with the use of SOAL. Subgroup analysis showed that the majority of formulas with SOAL in prediction accuracy for eyes with an AL ≥26 mm (p < 0.05). CONCLUSIONS: The refractive prediction accuracy in silicone oil-filled eyes was improved by correcting the AL measurement error of the IOLMaster 700, especially for long eyes.

Choice of intraocular lens calculation formula for cataract patients with prior pars plana vitrectomy.

PURPOSE: To determine the optimal intraocular lens (IOL) calculation formula for vitrectomized eyes with diverse surgical and biometric characteristics. SETTING: Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China. DESIGN: Retrospective consecutive case series study. METHODS: This study included 974 vitrectomized eyes (974 patients) scheduled for phacoemulsification with IOL implantation. 11 formulas were evaluated: Barrett Universal II (BUII), Emmetropia Verifying Optical, Hoffer-QST, Kane, Ladas Super Formula, Pearl-DGS, Radial Basis Function (RBF), Haigis, HofferQ, Holladay1, and SRK/T. Risk factors for prediction error (PE) exceeding 1 diopter (D) were determined using multiple logistic regression. Subgroup analyses were performed based on surgical history and biometric parameters. RESULTS: The risk of hyperopic PE (>1 D) was higher in patients with silicone oil tamponade (odds ratio [OR], 1.82) and longer axial length (AL) (OR, 1.55), while patients with previous scleral buckling (OR, 2.43) or ciliary sulcus IOL implantation (OR, 6.65) were more susceptible to myopic PE (<-1 D). The Kane formula had the highest overall prediction accuracy, and also the best in silicone oil-filled eyes and the flat cornea subgroup. The BUII and RBF displayed the optimal performance in eyes with previous scleral buckle and steep cornea, respectively. In eyes with an AL ≥ 26 mm, the Holladay1 with the nonlinear version of the Wang-Koch AL adjustment (Holladay1-WKn) showed the lowest absolute PE and highest percentage within ± 1.0 D of PE. CONCLUSIONS: The Kane achieved the highest overall prediction accuracy in vitrectomized eyes. The optimal formula for eyes with previous scleral buckle, steep cornea, or long AL was BUII, RBF, and Holladay1-WKn, respectively.

Comparison of axial length measurements in silicone oil-filled eyes using SS-OCT and partial coherence interferometry.

PURPOSE: To compare axial length (AL) measurements in silicone oil (SO)-filled eyes using swept-source optical coherence tomography (SS-OCT) (the IOLMaster 700 and OA2000) and partial coherence interferometry (the IOLMaster 500). SETTING: Zhongshan Ophthalmic Center, Guangzhou, China. DESIGN: Cross-sectional study. METHODS: We enrolled phakic patients who underwent SO removal surgery. The AL measurements by the IOLMaster 500, IOLMaster 700, and OA2000, both before and after SO removal, were compared. Multiple regression analysis was performed to identify risk factors for the differences between preoperative and postoperative AL measurements. RESULTS: 68 patients (68 eyes) with a mean age of 46.43 ± 13.24 years were included. No statistically significant difference was observed in the preoperative AL measurements between the IOLMaster 500 and IOLMaster 700 (25.48 ± 2.51 mm vs 25.49 ± 2.46 mm; P = .63), whereas the OA2000 yielded shorter AL (25.34 ± 2.36 mm) (both P < .001). After SO removal, the AL measurements showed no statistically significant differences among the 3 devices. In reference to the postoperative AL, the IOLMaster 500 and IOLMaster 700 tended to overestimate the AL in SO-filled eyes (both P < .001), and this measurement error increased with longer AL (ß = 0.08 and 0.05, respectively; both P < .001). No statistically significant difference was observed between preoperative and postoperative AL measurements by the OA2000 ( P = .18). CONCLUSIONS: The OA2000 is the preferred biometer for AL measurement in SO-filled eyes, whereas the IOLMaster 500 and IOLMaster 700 overestimate the AL especially for long eyes, which needs adjustment in clinical use.

[Comparison of stability of acrylic intraocular lens and transparency of lens capsule using Pentacam Scheimpflug System].

OBJECTIVE: To compare the amounts of intraocular lens (IOL) decentration and tilt, the anterior chamber depth (ACD) and the degree of posterior capsule opacification (PCO) using the Pentacam Scheimpflug System after cataract surgery between eyes with 1-piece acrylic IOL and 3-piece acrylic IOL. METHODS: It was a perspective study. Fifty-one patients with bilateral senile cataract had implantation of a 1-piece SA60AT IOL in one eye and a 3-piece MA60BM IOL in the contralateral eye. The amount of IOL decentration, tilt, the ACD, and the degree of PCO was measured using the Pentacam Scheimpflug System 1 day and 1, 6, 12 and 24 months postoperatively. RESULTS: There were no significant changes during the 24 m follow-up period in the decentration (0.37 ± 0.16, 0.36 ± 0.15, 0.36 ± 0.16, 0.37 ± 0.15, 0.38 ± 0.16), tilt (3.59 ± 0.91, 3.64 ± 0.92, 3.61 ± 0.90, 3.63 ± 0.90, 3.70 ± 0.89) or PCO (22.20 ± 3.99, 21.96 ± 4.00, 22.40 ± 4.03, 22.53 ± 4.00, 22.95 ± 3.87) in the 1-piece SA60AT group (F = 1.938, 0.785, 1.814; P > 0.05) or in the 3-piece MA60BM group (0.34 ± 0.14, 0.33 ± 0.14, 0.34 ± 0.14, 0.35 ± 0.14, 0.36 ± 0.14), (3.55 ± 0.90, 3.57 ± 0.92, 3.63 ± 0.88, 3.61 ± 0.88, 3.65 ± 0.89), (21.14 ± 3.88, 20.98 ± 3.87, 21.23 ± 3.83, 21.59 ± 3.82, 21.65 ± 3.87) (F = 1.004, 0.525, 1.963; P > 0.05). There was no significant difference between the two groups in IOL decentration (t = 0.802, 0.701, 0.588, 0.898, 0.631), tilt (t = 0.199, 0.337, 0.094, 0.121, 0.248) or PCO (t = 1.214, 1.119, 1.334, 1.082, 1.517) at any time points (P > 0.05). The ACD did not change after the surgery in the 1-piece group (3.90 ± 0.99, 3.88 ± 1.07, 3.91 ± 1.01, 3.90 ± 1.02, 3.92 ± 1.02) (F = 1.333, P > 0.05) but was significantly deeper in the 3-piece group (4.37 ± 1.02, 3.90 ± 0.98, 3.95 ± 0.99, 3.93 ± 0.96, 3.97 ± 0.99) (F = 92.757, P < 0.05) one day after the operation. The ACD was more shallow in the 1-piece SA60AT group than in the 3-piece MA60BM group at all time points. However, the difference was statistically significant only at 1 day after surgery (t = 102.944, P < 0.05). CONCLUSIONS: The degrees of IOL decentration, tilt, ACD and PCO in eyes with a 1-piece acrylic IOL with flexible haptics implanted in the capsular bag were similar to those in eyes with a 3-piece acrylic IOL with rigid PMMA haptics. But the 1-piece acrylic IOL provides a better stability than the 3-piece acrylic IOL in the early stage postoperatively.

Accuracy of new-generation intraocular lens calculation formulas in eyes undergoing combined silicone oil removal and cataract surgery.

PURPOSE: To compare the performance of new-generation and traditional intraocular lens (IOL) calculation formulas in eyes undergoing combined silicone oil (SO) removal and cataract surgery and to evaluate the prediction accuracy of Wang-Koch (WK) adjustment in SO-filled long eyes. SETTING: Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China. DESIGN: Retrospective consecutive case-series study. METHODS: New-generation formulas (Barrett Universal II, Emmetropia Verifying Optical, Kane, and Ladas Super formulas) and traditional formulas (Haigis, Hoffer Q, Holladay 1, and SRK/T formulas) were compared. The performance of WK adjustment was assessed in eyes with axial length more than 26 mm. The median absolute error (MedAE) was the main parameter to evaluate the accuracy of formulas. RESULTS: A total of 211 participants (211 eyes) who underwent combined SO removal and phacoemulsification with IOL implantation were included. Four new-generation formulas displayed statistically significant lower MedAE (0.32 to 0.35 diopter [D]) and higher percentage of eyes within ±1.00 D of prediction error (85.31% to 87.20%) compared with those of the traditional formulas (MedAE: 0.39 to 0.50 D; ±1.00 D: 81.04% to 81.99%, P < .05). For SO-filled long eyes, all traditional formulas showed hyperopic bias (0.36 to 0.65 D, P < .05), except for Haigis formula (0.28 D, P = .083), and this bias could be corrected by WK adjustment (P > .05). EVO formula displayed the lowest MedAE both in total (0.32 D) and in long eyes (0.33 D). CONCLUSIONS: New-generation formulas and traditional formulas with WK adjustment showed satisfactory prediction accuracy in eyes undergoing combined SO removal and cataract surgery. EVO formula displayed the highest accuracy.

Controlled release of corticosteroid with biodegradable nanoparticles for treating experimental autoimmune uveitis.

Noninfectious uveitis is a potentially blinding ocular condition that often requires treatment with corticosteroids to prevent inflammation-related ocular complications. Severe forms of uveitis such as panuveitis that affects the whole eye often require a combination of topical and either regional or systemic corticosteroid. Regional corticosteroids are currently delivered inside the eye by intravitreal injection (e.g. Ozurdex®, an intravitreal dexamethasone implant). Intravitreal injection is associated with rare but potentially serious side effects, including endophthalmitis, retinal and vitreous hemorrhage, and retinal detachment. Subconjunctival (SCT) injection is a less invasive option that is a common route used for post-surgical drug administration and treatment of infection and severe inflammation. However, it is the water soluble form of dexamethasone, dexamethasone sodium phosphate (DSP), that has been demonstrated to achieve high intraocular penetration with subconjunctival injection. It is difficult to load highly water soluble drugs, such as DSP, and achieve sustained drug release using conventional encapsulation methods. We found that use of carboxyl-terminated poly(lactic-co-glycolic acid) (PLGA) allowed encapsulation of DSP into biodegradable nanoparticles (NP) with relatively high drug content (6% w/w) if divalent zinc ions were used as an ionic "bridge" between the PLGA and DSP. DSP-Zn-NP had an average diameter of 210 nm, narrow particle size distribution (polydispersity index ~0.1), and near neutral surface charge (-9 mV). DSP-Zn-NP administered by SCT injection provided detectable DSP levels in both the anterior chamber and vitreous chamber of the eye for at least 3 weeks. In a rat model of experimental autoimmune uveitis (EAU), inflammation was significantly reduced in both the front and back of the eye in animals that received a single SCT injection of DSP-Zn-NP as compared to animals that received either aqueous DSP solution or phosphate buffered saline (PBS). DSP-Zn-NP efficacy was evidenced by a reduced clinical disease score, decreased expression of various inflammatory cytokines, and preserved retinal structure and function. Furthermore, SCT DSP-Zn-NP significantly reduced microglia cell density in the retina, a hallmark of EAU in rats. DSP-Zn-NP hold promise as a new strategy to treat noninfectious uveitis and potentially other ocular inflammatory disorders.