Effect of liposomal formulation of ascorbic acid on corneal permeability.

Ascorbic acid (AA) has a pivotal role in corneal wound healing via stimulating the biosynthesis of highly organized extracellular matrix components, but its rapid degradation and low corneal permeability limits its therapeutic effects. In this paper, we present the pharmacokinetic properties of a liposomal-based formulation of AA in terms of corneal permeation. Chemical stability, shelf-life, and drug release rate of lyophilized liposome (AA-LLipo) formulation was determined in comparison to free-form of AA solution using high-performance liquid chromatography (HPLC) and rapid equilibrium dialysis. In vitro transcorneal permeability was studied using a parallel artificial membrane permeability assay (PAMPA). Ex vivo permeation was examined on AA-LLipo-treated porcine cornea by determining the AA content on the ocular surface, in the cornea as well as in the aqueous humor using HPLC, and by Raman-mapping visualizing the AA-distribution. Our results showed that the liposomal formulation improved the chemical stability of AA, while drug release was observed with the same kinetic efficiency as from the free-form of AA solution. Both corneal-PAMPA and porcine corneal permeability studies showed that AA-LLipo markedly improved the corneal absorption kinetics of AA, thus, increasing the AA content in the cornea and aqueous humor. AA-LLipo formulation could potentially increase the bioavailability of AA in corneal tissues.

Evaluation of femtosecond laser-assisted and manual clear corneal incisions and their effect on surgically induced astigmatism and higher-order aberrations.

PURPOSE: To evaluate femtosecond laser-assisted and manual clear corneal incisions and their effect on surgically induced astigmatism (SIA) and corneal higher-order aberrations (HOAs). METHODS: In a prospective randomized study, conventional phacoemulsification with a 2.8-mm clear corneal incision using a disposable keratome was performed in 20 eyes of 20 patients (manual group), and femtosecond laser-assisted cataract surgery with a 2.8-mm biplanar clear corneal tunnel created by a femtosecond laser (LenSx; Alcon Laboratories, Inc., Aliso Viejo, CA) was performed in 20 eyes of 20 patients (femtosecond laser group). Corneal topography readings and corneal wavefront aberrations (diameter: 9.0 mm) were obtained using a Scheimpflug camera (Pentacam HR; Oculus Optikgerate, Wetzlar, Germany) preoperatively and 3 months postoperatively. RESULTS: There was no significant difference in SIA between the groups (femtosecond laser group: 0.47 ± 0.13 vs manual group: 0.41 ± 0.14; P = .218), but the axis deviation of the SIA axis from the previously planned axis was significantly smaller in the femtosecond laser group compared to the manual group (4.47°± 2.59° vs 7.38°± 4.72°, respectively; P = .048). Corneal HOAs increased significantly in both groups (femtosecond laser group: 0.13 ± 0.09 to 0.18 ± 0.12, P = .025; manual group: 0.13 ± 0.05 to 0.15 ± 0.05, P = .002), but preoperative and postoperative values did not differ significantly between them (P = .472 and .078, respectively). Lower-order and total corneal aberration values remained stable in both groups (P > .05). CONCLUSIONS: There was no difference in SIA and induced HOAs between manual and femtosecond laser-created clear corneal incisions.

Femtosecond laser-assisted cataract surgery in management of phacomorphic glaucoma.

PURPOSE: To report the use of femtosecond laser-assisted cataract surgery in management of phacomorphic glaucoma. METHODS: An 89-year-old patient developed acute phacomorphic glaucoma in her right eye with elevated intraocular pressure (62 mm Hg), shallow anterior chamber, and mature cataract. After conservative antiglaucoma therapy and Nd:YAG iridotomy, femtosecond laser-assisted cataract surgery was performed. A Malyugin ring was implanted for mechanical pupil dilatation and a 4.8-mm capsulorrhexis and lens fragmentation was performed using a femtosecond laser system (Alcon LenSx Inc., Aliso Viejo, CA) followed by in-the-bag intraocular lens implantation. RESULTS: Intact 4.8-mm capsulorrhexis and successful lens fragmentation could be performed using femtosecond laser. After cataract surgery, the patient's visual acuity increased from hand motions to 0.4 (Snellen 4/10) and the intraocular pressure returned to normal range without antiglaucoma drop therapy. CONCLUSIONS: The results indicate that femtosecond laser can be successfully used in certain cases of phacomorphic glaucoma, even if mechanical pupil dilatation is needed.

[Microkeratome-assisted anterior lamellar keratoplasty for the removal of corneal scar, caused by pterygium]. / Pterygium okozta torzító corneaheg eltávolítása mikrokeratommal végzett lamelláris keratoplasztikával.

AIM: to present our experience with microkeratome-assisted anterior lamellar keratoplasty using a manual microkeratome. MATERIALS AND METHODS: left eye of a 67 year old man was operated with microkeratome-assisted lamellar keratoplasty to remove a central corneal scar of the anterior stroma and to reduce secondary high-degree irregular astigmia caused by pterygium remnant. Videokeratography was performed to record the status of the cornea. RESULTS: postoperative best-corrected visual acuity was superior to preoperative value which was 0.6 with +7.0 spherical and -2.0 cylindrical Diopters before the operation. Uncorrected visual acuity improved from 0.15 to 0.6. The topographical cylinder decreased from 7.98 D to 3.79 D, surface asymmetry index from 2.42 to 1.48, surface regularity index form 3.24 to 1.72. Minimum keratometry reading increased from 38.35 to 41.69. CONCLUSION: microkeratome-assisted anterior lamellar keratoplasty seems to be safe and effective to remove corneal scars and reduce high degree irregular astigmia, moreover, to improve visual acuity.