Mathematical approximation of Orbscan II central corneal thickness to contact ultrasound.

PURPOSE: To compare Orbscan II central corneal thickness (CCT) measurements corrected by five mathematical methods with ultrasound (US) CCT measurements. METHODS: The preoperative CCT examinations of the right eyes of 3242 consecutive candidates for refractive surgery were retrospectively reviewed. Raw Orbscan data were processed by five correction methods: multiplication, subtraction, polynomial, logarithmic, and power. For each correction method, the concordance between corrected Orbscan and US pachymetries was assessed by mean, Pearson correlation, regression analysis, 95% limits of agreement (LoA), and percentage of eyes within 8 µm of US pachymetry. RESULTS: Throughout the 3242 eyes analyzed, we found a high Pearson correlation between Orbscan and US measurements with all correction methods assessed. The linear multiplication and subtraction correction methods brought about mean Orbscan CCT similar to mean US CCT measurements. However, they led to relatively high 95% LoA intervals and low percentage of eyes within 8 µm of US pachymetry. In contrast, the three nonlinear correction methods proposed herein for the first time narrowed the 95% LoA interval (Bland-Altman analysis) together with providing mean Orbscan CCT similar to mean US CCT measurements. Moreover, the power fit was the only method that was reproducible when extracted from one subset of the cohort and applied in another. CONCLUSIONS: Broad 95% LoA intervals were obtained when applying the multiplication and the subtraction correction methods, indicating a poor agreement between the devices. We suggest the power fit as the default method for adjusting Orbscan to US CCT readings.

LASIK correction of vision in adults with unilateral amblyopia.

PURPOSE: to evaluate the effects of laser refractive surgery in adult patients with mild to moderate amblyopia due to anisometropic myopia. METHODS: a retrospective review of 30 patients (60 eyes) with unilateral amblyopia (corrected distance visual acuity [CDVA] 0.6 or worse) who underwent simultaneous bilateral laser vision correction using the Technolas 217z excimer laser (Bausch & Lomb) was performed. Mean patient age was 31.03 ± 10.05 years (range: 18 to 53 years). Visual outcomes in the amblyopic eye were compared with those in the fellow nonamblyopic control eye of the same patient. RESULTS: mean preoperative CDVA improved in amblyopic eyes from 0.50 ± 0.13 to 0.57 ± 0.20 postoperatively (average gain of 0.075 ± 0.14; P=.007) and improved from 0.92 ± 0.12 preoperatively to 0.93±0.15 after surgery (mean gain of 0.013 ± 0.14; P=.603) in the fellow nonamblyopic eyes. The safety index was significantly greater in the amblyopic eyes compared with the nonamblyopic fellow eyes (1.15 ± 0.30 vs 1.02 ± 0.15, P=.035), therefore, no difference was noted in efficacy (P=.913). Five of 30 eyes with mild to moderate amblyopia gained 2 to 4 lines of CDVA. CONCLUSIONS: laser refractive surgery for myopic correction was found to be safe and effective in eyes with mild to moderate amblyopia.

Topical and intravitreous administration of cationic nanoemulsions to deliver antisense oligonucleotides directed towards VEGF KDR receptors to the eye.

Antisense oligonucleotides (ODNs) specific for VEGFR-2-(17 MER) and inhibiting HUVEC proliferation in-vitro were screened. One efficient sequence was selected and incorporated in different types of nanoemulsions the potential toxicity of which was evaluated on HUVEC and ARPE19 cells. Our results showed that below 10 microl/ml, a 2.5% mid-chain triglycerides cationic DOTAP nanoemulsion was non-toxic on HUVEC and retinal cells. This formulation was therefore chosen for further experiments. In-vitro transfection of FITC ODNs in ARPE cells using DOTAP nanoemulsions showed that nanodroplets do penetrate into the cells. Furthermore, ODNs are released from the nanoemulsion after 48 h and accumulate into the cell nuclei. In both ex-vivo and in-vivo ODN stability experiments in rabbit vitreous, it was noted that the nanoemulsion protected at least partially the ODN from degradation over 72 h. The kinetic results of fluorescent ODN (Hex) distribution in DOTAP nanoemulsion following intravitreal injection in the rat showed that the nanoemulsion penetrates all retinal cells. Pharmacokinetic and ocular tissue distribution of radioactive ODN following intravitreal injection in rabbits showed that the DOTAP nanoemulsion apparently enhanced the intraretinal penetration of the ODNs up to the inner nuclear layer (INL) and might yield potential therapeutic levels of ODN in the retina over 72 h post injection.

Quantitative assessment of bandage soft contact lens wear immediately after LASIK.

PURPOSE: To evaluate the efficacy and tolerability of overnight bandage soft contact lenses applied immediately after LASIK. METHODS: Bandage soft contact lenses were applied immediately following bilateral simultaneous LASIK in 161 consecutive patients. Signs and symptoms associated with contact lens wear were prospectively recorded at 1 hour, 4 hours, and the following morning, using a standardized questionnaire. Contact lenses were removed at 1 hour if patients were symptomatic of intolerance. If no signs of contact lens intolerance appeared at 1 hour, the lenses were removed the following morning. No contact lenses were applied in 61 patients after LASIK. RESULTS: One hour after the procedure, contact lenses were removed from 47 patients due to intolerance. In these patients, contact lens removal was associated with a significant decrease of the total score the next morning (0.31±0.55) compared to 1 hour (5.65±1.60, P<.0001). A similar decrease of the total score was noted in those patients who tolerated the contact lenses (0.20±0.52 vs 1.30±1.78) and those in whom the contact lenses were not applied (0.76±1.19 vs 3.24±1.93). Mucoid discharge at the lid margins was noted in 52.6% of patients and mild corneal edema was noted in 28.8% of patients with bandage soft contact lenses at 12 to 18 hours. CONCLUSIONS: Bandage soft contact lens application after LASIK is associated with significant reduction of symptoms during the immediate postoperative period. However, removal of these lenses may be necessary shortly after the procedure.

Methylprednisolone delivery to the back of the eye using hydrogel iontophoresis.

AIM: The aim of this study was to evaluate methylprednisolone penetration into ocular structures after low-current trans-scleral hydrogel iontophoresis, as compared with the common intravenous (i.v.) treatment. METHODS: Methylprednisolone hemisuccinate (MPH) iontophoresis was studied in rabbits, using drug-loaded hydrogels mounted on a portable iontophoretic device. Cathodal iontophoresis of 2.6 mA/cm(2) was applied for 5 min at two opposite sites on the sclera or for 10 min at the same site. Ocular drug levels were determined 2 h after iontophoretic treatment, then compared to mock iontophoresis and i.v. infusion of 10 mg/kg methylprednisolone. RESULTS: Significantly higher methylprednisolone levels were found in ocular tissues after iontophoresis, compared with the control groups, except for the sclera concentrations, which were similar to the concentrations achieved after mock iontophoresis. Two (2) h after the trans-scleral iontophoretic treatment, 178.59 +/- 21.63 microg/g, 6.74 +/- 2.38 microg/ml, and 2.71 +/- 0.57 microg/mL were found in the retina, aqueous humor, and vitreous, respectively. No significant differences were found between one or two site treatments of trans-scleral iontophoresis. Nondetectable concentrations were found 2 h after the i.v. infusion of 10 mg/kg of methylprednisolone in all evaluated ocular tissues and fluids. CONCLUSIONS: A short, low-current noninvasive iontophoretic treatment, using methylprednisolone-loaded hydrogels, has potential clinical value in treating ocular inflammatory diseases.

In vitro and in vivo evaluation of carboplatin delivery to the eye using hydrogel-iontophoresis.

PURPOSE: To investigate in vitro and in vivo hydrogel-iontophoresis delivery of carboplatin to the eye. METHODS: Iontophoresis was applied on agar gels resembling the eye using different current intensities and durations. Transscleral iontophoresis was performed on healthy rabbits, applying 0, 1, and 3 mA current for 10 min. RESULTS: Similar drug concentrations were obtained in all experimental groups, in in vitro and in vivo studies, regardless of the iontophoretic current applied. A 20-mm penetration depth was found for carboplatin at the agar model. High drug levels were found at the sclera and retina, while lower levels were found at ocular fluids. CONCLUSION: Carboplatin-iontophoretic application at the above conditions does not have an obvious advantage over passive penetration due to high diffusion properties and insufficient molecular charge. Passive carboplatin diffusion from loaded hydrogels inserted in the lower cul-de-sac should be further investigated as a potential clinical treatment for intraocular retinoblastoma.

Charged nanoparticles delivery to the eye using hydrogel iontophoresis.

Ocular iontophoresis has been investigated for many years as a non-invasive technique for enhancing ionized drug penetration through ocular tissues. In this study we assessed the penetration of charged fluorescent nanoparticles into rabbit eyes using hydrogel iontophoresis. Particle distribution into ocular tissues and penetration efficiency of negative nanoparticles compared with positive nanoparticles was also evaluated. Cathodal and anodal iontophoretic administrations were performed using polyacrylic hydrogels loaded with charged nanoparticle suspension (20-45 nm), applying a current intensity of 1.5 mA for 5 min onto the cornea and sclera. At pre-set time points post treatment, eyes were dissected and tissues were evaluated for fluorescence intensity. Strong fluorescence evidence was observed at anterior and posterior ocular tissues. Negative particle distribution profile revealed fast uptake into the outer ocular tissues, within 30 min post treatment, followed by particle migration into the inner tissues up to 12 h post treatment. The positively charged particles demonstrated better penetration abilities into inner ocular tissues compared to the negatively charge particles. This work provides an opening for the development of a new ocular therapeutic pathway using iontophoresis of extended release drug-loaded charged nanoparticles.

Methotrexate delivery to the eye using transscleral hydrogel iontophoresis.

PURPOSE: To evaluate methotrexate penetration and distribution profile in ocular structures after short low current transscleral hydrogel iontophoresis. METHODS: Methotrexate iontophoresis was studied in rabbits using drug-loaded hydrogels mounted on a portable iontophoretic device. Drug distribution profile was evaluated 2, 4, and 8 hours after iontophoretic treatment of 1.6 mA/cm2 for 4 min. Ocular drug levels were also determined two hours after iontophoretic treatment of 5 mA/cm2, compared to mock iontophoresis and intravitreal injection of methotrexate. RESULTS: Therapeutic drug levels were maintained for at least 8 h at the sclera and retina and for 2 h at the aqueous humor following the iontophoretic treatment. After increasing the current density, a twice-higher concentration was achieved at the vitreous and 8 to 20 time higher concentrations at the retina and sclera. CONCLUSIONS: A short low current non-invasive iontophoretic treatment using methotrexate-loaded hydrogels has a potential clinical value in treating ocular inflammatory diseases and intraocular lymphoma.

Early transient visual acuity loss after LASIK due to steroid-induced elevation of intraocular pressure.

PURPOSE: To report the clinical course of early transient reduction of uncorrected visual acuity (UCVA) after LASIK surgery resulting from steroid-induced elevation of intraocular pressure (IOP). METHODS: Twenty-nine eyes of 15 patients who received topical corticosteroids after uneventful myopic LASIK surgery and had a decrease in UCVA within the first 3 weeks were evaluated retrospectively. RESULTS: Intraocular pressure increased by 4 to 30 mmHg from preoperative to postoperative days 4 to 20. Twenty-seven of 29 eyes had a decrease in UCVA and/or best spectacle-corrected visual acuity (BSCVA). All eyes, except one, had edema without evidence of inflammation in the interface or the remainder of the cornea. Discontinuation of topical corticosteroids and application of anti-glaucoma medications resulted in a decrease of IOP to normal levels, reduction or disappearance of the edema, and recovery of BSCVA. CONCLUSIONS: Early onset steroid-induced elevation of IOP after LASIK may cause corneal edema and a sudden decrease in UCVA. Rapid diagnosis and treatment can control IOP and recover the visual loss.

Conjunctival autografting combined with low-dose mitomycin C for prevention of primary pterygium recurrence.

PURPOSE: To compare the clinical outcome of pterygium surgery combining intraoperative mitomycin C (MMC) with a free conjunctival autograft, with three other methods of pterygium surgery, including intraoperative MMC alone, conjunctival autograft alone, and bare sclera without adjunctive treatment. DESIGN: Interventional, randomized and in part nonrandomized, prospective, comparative study. METHODS: setting: A university medical center department of ophthalmology. STUDY POPULATION: One hundred and twenty patients underwent pterygium excision surgery. These patients were divided into four treatment groups. INTERVENTION: In group 1 (30 patients), MMC, 0.2 mg/ml, was applied for three minutes. In group 2 (30 patients), conjunctival autografting was performed. Group 3 (30 patients) received sodium chloride 0.9% only, and group 4 (30 patients) underwent conjunctival autografting combined with one minute application of MMC, 0.2 mg/ml. MAIN OUTCOME MEASURE: Recurrence rates and complications. RESULTS: Pterygium recurred in two patients (6.6%) in group 1, in four patients (13.3%) in group 2, in 14 patients (46.6%) in group 3, and in none of the patients in group 4. chi(2) analysis revealed a significantly lower recurrence rate in group 4 compared with group 2 (P = .038) and with group 3 (P < .0001). Epithelialization of the wounds was complete within 14 days of surgery. No complications were demonstrated in any of the study groups except for one case of minor melting of the flap in group 4. CONCLUSIONS: This study indicates that pterygium excision with a free conjunctival autograft combined with intraoperative low-dose MMC is a safe and effective technique in pterygium surgery.