Live Rabbits Research Articles

CO2 Laser-assisted Sclerectomy Surgery Part I

To evaluate the safety and performance of a second-generation device for CO2 laser-assisted sclerectomy surgery system in experimental models. Laser-assisted deep sclerectomy using a modified CO2 laser system (OT-134-"IOPtiMate"; IOPtima Ltd, Israel) was performed in 3 experimental models: enucleated pig eyes, human cadaver eyes, and live rabbit eyes. A half-thickness scleral flap was created, and a CO2 laser with a beam-manipulating system was used to achieve deep scleral ablation over the Schlemm canal zone. Aqueous percolation and scleral perforation rates were recorded. Intraocular pressure was monitored in live rabbits up to 21 days postoperatively. The shape and location of the scleral ablation zone, thermal damage, and the healing process were examined by histopathological analysis. Deep scleral ablation and aqueous percolation were repeatedly achieved in all the models. Micro-perforations occurred in 4/18 human eyes (22.2%), in 4/23 rabbit eyes (17.4%), and in none of the 38 porcine eyes. Mean intraocular pressure in the rabbits was significantly decreased (by 6.3±3.6 mm Hg) on the first postoperative day (P<0.0001) and gradually returned to normal. In all but one of the cadaver eyes, effective fluid percolation was achieved. Histology in each case disclosed deep scleral craters with a thin intact sclero-corneal tissue layer at the ablation area. Mild thermal damage, limited to the ablated scleral walls was detected and resolved after 10 days. The results in these experimental studies indicated that CO2 laser-assisted sclerectomy surgery using the OT-134 system is a safe and efficacious procedure for achieving effective fluid percolation.

Pharmacokinetic Features of Difluprednate Ophthalmic Emulsion in Rabbits as Determined by Glucocorticoid Receptor-Binding Bioassay

Difluprednate (6α,9-difluoro-11β,17,21-trihydroxy-1,4-pregnadiene-3,20-dione 21-acetate 17-butyrate, DFBA) has long been used as an anti-inflammatory dermatological agent. The main objectives of the current study were to evaluate the pharmacokinetic and pharmacodynamic features of DFBA when used as an ophthalmic agent, and to compare these features with those of other common ophthalmic agents, to determine which has the highest activity. A glucocorticoid (GC) receptor-binding test was performed to evaluate GC receptor-binding activity (GCRBA, the index of pharmacological effect). Using this information, we calculated dose-response curves, IC(50) values, and K(d) values to evaluate each drug's K(i) value. Finally, we performed studies in live rabbits to compare the activity of 4 formulations [0.002%, 0.01%, or 0.05% DFBA, or an ophthalmic solution of 0.1% betamethasone sodium phosphate (BMP)] at 4 time points (0.5, 1, 2, 4 h). At each time point, blood and eye samples were taken so that C(max) (the maximum equivalent concentration of the active DFBA metabolite, DFB), T(max) (the time at which C(max) was measured), and the area under the concentration-time curve could be compared across the 4 formulations. BMP had the highest K(i) value (8.4 × 10(-8) nmol/L), whereas DFB had the lowest (6.1 × 10(-11) nmol/L). The GCRBA of DFBA was intermediate to these 2 values (7.8 × 10(-10) nmol/L). Instillation of the DFBA ophthalmic emulsion in the eyes of rabbits led to dose-dependent increases in GCRBA, which was mostly attributable to the activity of DFB. The 0.05% DFBA ophthalmic emulsion elicited the greatest response in both aqueous humor and iris/ciliary body tissues, though there were no significant dose-dependent differences in GCRBA in plasma samples. The 0.05% DFBA ophthalmic emulsion appears to be an effective and safe anti-inflammatory treatment in ocular tissues. It is comparable, and possibly even superior, to the 0.1% BMP solution, and may be particularly useful in cases of severe disease where treatment with BMP solution alone is insufficient.

Effect of H-7 on Secondary Cataract After Phacoemulsification in the Live Rabbit Eye

This study is aimed to determine if the serine-threonine kinase inhibitor H-7 inhibits secondary cataract after phacoemulsification in the live rabbit eye. Eighteen rabbits underwent extracapsular lens extraction by phacoemulsification in 1 eye. The eye was treated with intravitreal H-7 (300 or 1,200 μM; n = 6 or 5) or balanced salt solution (BSS) (n = 7) immediately after the surgery and twice weekly for 10 weeks. Each eye received slit lamp biomicroscopy once a week, during which posterior capsule opacification (PCO) was evaluated. The eye was then enucleated and the lens capsule was prepared, fixed, and imaged. PCO was evaluated again on the isolated lens capsule under a phase microscope. Soemmering's ring area (SRA) and the entire lens capsule area were measured from capsule images on a computer and the percentage of SRA (PSRA) in the entire capsule area was calculated. Wet weight of the capsule (WW) was determined on a balance. No significant difference in PCO was observed in any comparison. No significant differences in SRA, PSRA, and WW were observed between the 300 μM H-7-treated eye and the BSS-treated eye. However, SRA, PSRA, and WW in the 1,200 μM H-7-treated eye were significantly smaller than those in the BSS-treated eye [28.3 ± 16.2 vs. 61.4 ± 8.86 mm(2) (P = 0.001), 33% ± 20% vs. 65% ± 15% (P = 0.01), and 65.6 ± 27.9 vs. 127.0 ±37.3 mg (P = 0.01)]. Intravitreal H-7 (1,200 μM) significantly inhibits Soemmering's ring formation in the live rabbit eye, suggesting that agents that inhibit the actomyosin system in cells may prevent secondary cataract after phacoemulsification.

Non-invasive in vivo measurement of the tear film using spatial autocorrelation in a live mammal model.

Tear film stability and its interaction with the corneal surface play an important role in maintaining ocular surface integrity and quality of vision. We present a non-invasive technique to quantify the pre-corneal tear film thickness. A cMOS camera is used to record the interference pattern produced by the reflections from multiple layers of the tear film Principles of spatial autocorrelation are applied to extract the frequency of the periodic patterns in the images. A mathematical model is developed to obtain the thickness of the tear film from the spatial autocorrelation image. The technique is validated using micro-fabricated thin parylene films. We obtained repeatable and precise measurement on a live rabbit model (N = 6). We obtained an average value of 10.2µm and standard deviation of, SD = 0.3 (N = 4). We measured one rabbit infected with HSV-1 virus that had a baseline tear film thickness of 4.7µm.

FULVIC ACID COATED IRON OXIDE NANOPARTICLES FOR MAGNETIC RESONANCE IMAGING CONTRAST AGENT

Fulvic acid coated Fe 3 O 4 superparamagnetic nanoparticles were synthesized by a coprecipitation technique with iron salts and a small molecule stabilizer-fulvic acid. The prepared nanoparticles were well dispersed in water with about 10 nm in size according to transmission electron microscopy (TEM) observations. Fourier transform infrared spectroscopy (FTIR) revealed that fulvic acid were successfully covalently bonded to Fe 3 O 4 through the two adjacent phenolic hydroxyl groups and the carboxyl (- COOH ) groups were functionalized to the surface. The vibrating sample magnetometer (VSM) result showed that the nanoparticles were superparamagnetic and the saturation magnetizations were 60 emu/g. Moreover, their efficacy of liver magnetic resonance imaging (MRI) contrast agent was investigated by using live rat and tumor-bearing rabbit models through conventional clinical 1.5T MRI.

Technical note: electronic identification of live rabbits ,preliminary study to identify a body injection site

Identification and monitoring of farm animals are effective tools for traceability. Current livestock identification systems are not 100% efficient and present certain disadvantages such as losses, breakages and an unreadable identification code. The use of injectable transponders may be a reliable method for individual identification, providing an improvement in data recording and farm management. The aim of this experiment was to evaluate the practical aspects concerning injection technique, readability and retrieval of injectable transponders in live rabbits. A total of 60 rabbits (40 fatteners and 20 does) were injected with 23x3mm passive FDX-B transponders (Datamars, Switzerland), inserted into a needle, wrapped in a sterilised package and applied by a specific injector (Planet ID, Germany). Two different body sites were evaluated: back scapular (n=30) and armpit (n=30) position. The readings of the transponders were performed by using an i-max plus portable reader (Datamars, Switzerland) at different times: before and after injection, one day, one week and one month after injection. Does were read monthly during 1 year, while fatteners before the slaughtering process. To evaluate the effect on productive performance, fattening rabbits were compared to a control group. The readability of transponders injected in fatteners until slaughter and in does until 1 year after injection was 100%. No harmful effects were observed and no significant difference in weight was found in the two injection groups, compared with the control group. The retrieval was performed by a single operator at skinning, with 100% of transponders recovered. The site of the injection did not affect the migration rate, although it was high in both cases. The feasibility of subcutaneous transponder injection in live rabbits is recommended in the two body positions analysed. However, specific training and operator experience are necessary to improve the efficiency of this identification system.

Visual image analysis to estimate morphological and weight measurements in rabbits.

Visual Image Analysis (VIA) has been evaluated to estimate morphological traits and weights of live rabbits and carcasses to improve the body conformation of the new breed Leprino di Viterbo. The reliability of VIA was firstly tested on a sample of 30 does. Then, a total of 365 animal (130 additional does and 205 rabbits at slaughtering weight of kg 2.5) was utilised to calculate some surface traits and correlations between live and carcass weights that were later validated over a new sample of 112 rabbits (37 does and 75 fattened). VIA gave very good results to evaluate morphological and weight measurements. Maximum observed individual difference between data measured by metre and by VIA was only 3.6%. Since standard error (SE) of VIA was lower than SE of metre (0.06 and 0.33 respectively), VIA was considered more reliable than the instrumental measurement. A new parameter, Body Side Surface, was made available by the Image Analysis to estimate Live Weight and Carcass Weight efficiently. Correlations were high (P<0.01) both in does (R2=0.87 for live weight equation) and at slaughter time (R2=0.82 and 0.76 for live and carcass weight equations, respectively). It was concluded that VIA is a viable, quick and practical mean to measure and select for weight and morphological traits as head length, ear length, body length and body side surface.

THE CURRENT SITUATION IN RABBIT PRODUCTION IN HUNGARY

At present slaughter rabbit production in Hungary is 6 651 tonnes - less than half of that achieved in the peak years of 1982 and 1991. In 1998 live rabbit production amounted to a total of 13 903 tonnes. This production is exported in its entirety; there is practically no rabbit meat on the domestic market. Previously approx. 90% of rabbits slaughtered were sold to ltaly. At present ltaly accounts for 65-70% of Hungarian rabbit exports and Switzerland for 20-25%. The export of live rabbits practically ceased in 1986. In 1998 export shipments comprised 68% whole carcasses and 32% meat products. The majority of Hungarian rabbit abattoirs are now under foreign ownership or involve foreign partners. The abattoirs work on a one-shift system, at 50% of their shift capacity. Previously 95-98% of rabbits for slaughter were produced on small farms with 5-15 does. Now two abattoirs operate large-scale farms with 10,000 does, and there are approximately 60-70 medium-sized farms with between 100 and 3,000 does; 26% of meat rabbit purchases now originate from commercial production farms.Angora rabbit production reached its peak in 1988. With an annual output of 190 tonnes of Angora wool, Hungary was then the largest exporter in Europe. The dramatic drop in wool prices has forced production down to a sales level of approximately one tonne per year.

Staining and Imaging of Live Rabbit Embryos: Figure 1.

INTRODUCTIONThis protocol describes methods for supravital labeling of cellular proliferation and movement in rabbit embryos as well as for imaging of live cell movements. The techniques use localized labeling of epiblast cells with DiI by injection or by using comprehensive nuclear staining of all cell layers before and during early gastrulation. Because rabbit embryos implant relatively late during embryonic development, gastrulation-stage embryos can be isolated by flushing them from the uterus. Moreover, the embryonic disc is flat and translucent, providing a direct uncompromised overview of gastrulation while the whole blastocyst is protected by the zona pellucida. These properties allow examination of whole blastocysts either under the impact of changing environmental conditions (e.g., medium additives, oxygen concentrations) or following mechanical manipulation of the embryonic disc using a needle penetrating the zona pellucida. Further manipulation (e.g., transplantation) can be performed after removing the embryo from the zona and explantation of the embryonic disc. These techniques allow embryonic growth centers to be identified and single-cell movements to be recorded.

Evaluation of Acute Corneal Barrier Change Induced by Topically Applied Preservatives Using Corneal Transepithelial Electric Resistance In Vivo

We evaluated acute changes in corneal barrier function after instillation with preservatives using corneal transepithelial electric resistance (TER) in vivo and cytotoxicity tests in vitro. The corneal TER of live rabbits was measured using a volt-ohm meter and silver/silver chloride electrodes. The cornea was exposed to the preservatives benzalkonium chloride (BAC; 0.001%, 0.002%, 0.005%, 0.01%, and 0.02%), 0.04% paraben, 0.5% chlorobutanol, 0.005% chlorhexidine digluconate, 2% boric acid, and 0.01% ethylenediaminetetraacetic acid, and then changes in the TER were monitored for 60 seconds. Cultured normal rabbit corneal epithelial cells were exposed to the same preservatives for 60 seconds in vitro, and cell viability was evaluated using the WST-1 assay. The TER instantly decreased and became significantly lower than the control within 10 seconds after instillation with 0.01% and 0.02% BAC (P < 0.01) and within 60 seconds after that with 0.005% BAC (P < 0.01). The TER decreased concomitantly with increasing BAC concentration. Cell viability after instillation with 0.005%, 0.01%, and 0.02% BAC for 60 seconds was significantly lower than that of the control (P < 0.0001). None of the other preservatives significantly altered the TER or cell viability. Decreases in the TER correlated with cell viability (r = 0.94, P < 0.0001). Instillation with BAC immediately disrupted the corneal epithelium. Corneal epithelial cell death is supposed to be associated with a decline in barrier function; thus, corneal TER measurement in vivo can assess the acute toxicity of preservatives added to ophthalmic drugs.

Converging Stereotactic Radiotherapy Using Kilovoltage X-Rays: Experimental Irradiation of Normal Rabbit Lung and Dose–Volume Analysis With Monte Carlo Simulation

To validate the feasibility of developing a radiotherapy unit with kilovoltage X-rays through actual irradiation of live rabbit lungs, and to explore the practical issues anticipated in future clinical application to humans through Monte Carlo dose simulation. A converging stereotactic irradiation unit was developed, consisting of a modified diagnostic computed tomography (CT) scanner. A tiny cylindrical volume in 13 normal rabbit lungs was individually irradiated with single fractional absorbed doses of 15, 30, 45, and 60 Gy. Observational CT scanning of the whole lung was performed every 2 weeks for 30 weeks after irradiation. After 30 weeks, histopathologic specimens of the lungs were examined. Dose distribution was simulated using the Monte Carlo method, and dose-volume histograms were calculated according to the data. A trial estimation of the effect of respiratory movement on dose distribution was made. A localized hypodense change and subsequent reticular opacity around the planning target volume (PTV) were observed in CT images of rabbit lungs. Dose-volume histograms of the PTVs and organs at risk showed a focused dose distribution to the target and sufficient dose lowering in the organs at risk. Our estimate of the dose distribution, taking respiratory movement into account, revealed dose reduction in the PTV. A converging stereotactic irradiation unit using kilovoltage X-rays was able to generate a focused radiobiologic reaction in rabbit lungs. Dose-volume histogram analysis and estimated sagittal dose distribution, considering respiratory movement, clarified the characteristics of the irradiation received from this type of unit.

For your eye only

A contact lens with one LED that is powered wirelessly with radiofrequency (RF) is built. The conventional contact lenses made up of polymers are integrated with control circuits, communication circuits, and miniature antennas using custom-built optoelectronic components that include hundreds of LEDs. The lenses are successfully tested with live rabbits and can be a multipurpose, whether used as biosensors, displays, etc.

Feeding live prey to zoo animals: response of zoo visitors in Switzerland

In summer 2007, with the help of a written questionnaire, the attitudes of more than 400 visitors to the zoological garden of Zurich, Switzerland, toward the idea of feeding live insects to lizards, live fish to otters, and live rabbits to tigers were investigated. The majority of Swiss zoo visitors agreed with the idea of feeding live prey (invertebrates and vertebrates) to zoo animals, both off- and on-exhibit, except in the case of feeding live rabbits to tigers on-exhibit. Women and frequent visitors of the zoo disagreed more often with the on-exhibit feeding of live rabbits to tigers. Study participants with a higher level of education were more likely to agree with the idea of feeding live invertebrates and vertebrates to zoo animals off-exhibit. In comparison to an earlier study undertaken in Scotland, zoo visitors in Switzerland were more often in favor of the live feeding of vertebrates. Feeding live prey can counter the loss of hunting skills of carnivores and improve the animals' well-being. However, feeding enrichments have to strike a balance between optimal living conditions of animals and the quality of visitor experience. Our results show that such a balance can be found, especially when live feeding of mammals is carried out off-exhibit. A good interpretation of food enrichment might help zoos to win more support for the issue, and for re-introduction programs and conservation.

TU-D-210A-03: Where Sound Meets Electricity: The Acoustoelectric Effect in Biomedicine

The acoustoelectric (AE) effect is a well-documented interaction between local pressure and electric resistivity. In recent years, the phenomenon has been revived for applications in biomedical imaging and therapy. My laboratory is developing two new approaches based on this concept: 1) ultrasonic imaging of current flow and 2) novel detection and imaging of an acoustic beam. Ultrasound Current Source Density Imaging (UCSDI) is a new modality for mapping electrical current deep into tissue. This approach combines moderate acoustic pressure with recording electrode technology to directly image current densities. We have demonstrated feasibility of UCSDI in saline, tissue-equivalent phantoms, neural tissue and direct mapping of the cardiac activation wave in the live rabbit heart. Although potential applications of UCSDI are diverse, we are focusing on enhancing electrical cardiac mapping during ablation treatment of arrhythmias. There are several potential advantages of UCSDI over conventional electrophysiology and electrical imaging, highlighted by 1) enhanced spatial resolution determined by the size of the ultrasound focus (<1 mm); and 2) automatic co-registration of UCSDI with pulse echo ultrasound, depicting current density maps superimposed on heart structure and motion. In addition to UCSDI, we are also developing the AE hydrophone as a new device for detecting pressure and imaging an ultrasound beam. As clinical applications for ultrasound therapy continue to proliferate—from lithotripsy to ablation treatment of uterine fibroids and cancer—the need for simple, rapid, and accurate estimates of the acoustic field become increasingly important. The AE hydrophone does not depend on a piezoelectric material; instead, a small region with high current density is used as a gain mechanism for detecting ultrasonic waves. I will present early results from initial prototypes and compare with conventional hydrophones, as well as simulations. The AE hydrophone has attractive attributes not typically seen with other devices, including simple construction, low cost, decent sensitivity, and resistant to damage at high intensity ultrasonic fields.

Coating of Objects Introduced into the Oviduct of Pseudopregnant Rabbit Does

This investigation addresses the possibility of providing mouse embryos or other foreign objects with a protective mucin coat by transferring them into the oviduct of a live rabbit doe. Mouse embryos at the 8 or 16-cell stage, rabbit oocytes and latex spheres resembling mouse embryos in size were transferred to the ligated oviducts of ovulation-induced rabbit does. The does were killed 24 h later to have their oviducts flushed. A large proportion of the latex spheres (89%) and of the ovulated oocytes of the recipient does (92%) was recovered. The recovery rates for transferred rabbit oocytes, either intact or with the zona pellucida removed, were 61% and 51%, respectively, whereas that for mouse embryos was extremely poor (20%). Rabbit oocytes with or without zona were enveloped in a thick mucin coat regardless whether they had been transferred or ovulated by the recipients. The same applied to empty rabbit zonae. Mouse embryos and latex spheres were also covered by a mucin coat, but it was four times thinner. While residing in the rabbit oviduct, the mouse embryos continued developing to a stage comparable to what would have been expected in situ. During the subsequent in vitro culture, mouse embryos continued developing to the expanded blastocyst stage. They did, yet, not hatch from the zona. It may be concluded that particles of various origins, when placed into the oviduct of ovulated rabbit does, will be provided with a mucin covering which is, however, considerably thinner than that surrounding oocytes or zonae pellucidae originating from rabbits.

The Surface Modification of Nanocrystals for Biological and Environmental Applications

AbstractSuperparamagnetic nanoparticles can find many applications in different fields with greener techniques. The Fe3O4 nanoparticles less than 10nm coated with humic acid were synthesized by a chemical co-precipitation technique with cheap and environmental friendly iron salts and humic acid. The as-synthesized products were highly soluble in water. The efficacy for liver Magnetic resonance imaging (MRI) contrast agent was investigated by using it to the live rat and tumor-bearing rabbit models, on a conventional clinical 1.5 T MRI facility. Moreover the Fe3O4 –HA composite used in the Methylene Blue adsorption in neutral aqueous solution was studied too with high efficiency. The experimental results showed that the humic acid coated Fe3O4 superparamagnetic nanoparticles were suitalbe not only for liver MRI contrast agent, but also as adsorbents for removal of cationic organic dyes from neutral water.

Transgene expression of enhanced green fluorescent protein in cloned rabbits generated from in vitro-transfected adult fibroblasts

Live rabbits have previously been generated through nuclear transfer using adult cells as nuclear donors. We demonstrated in this study that transfected adult rabbit fibroblasts are also capable of supporting full-term development. The fibroblasts were transfected with a pEGFP-C1 plasmid using lipofectamine() 2000, and the transgenic cells were derived from conditioned medium. The transgenic fibroblasts were cultured until confluent and then serum-starved prior to be used as nuclear donors. After nuclear transfer and activation, 22% (12/55) of the transgenic cloned embryos developed to the blastocyst stage. A total of 114 embryos at the 4- to 8-cell stage were transferred to the oviducts of 8 pseudo-pregnant mothers; 5 of these animals became pregnant, and 3 of the 5 mother rabbits carried the pregnancy to term. Caesarean section was performed on the 3 pregnant mothers, yielding 4 kits, one of which has survived for more than 9 months. Green fluorescence could be detected in the toenails of the living cloned rabbit and the offspring from the living cloned rabbit under ultraviolet light. DNA analyses confirmed that all 4 cloned rabbits were genetically identical to the transgenic donor cells, and that they all carried the EGFP gene. The present study demonstrated that transgenic rabbits can be generated through nuclear transfer. These results may facilitate future developments in the genetic engineering of rabbits.

A new hope for noninvasive cancer treatment? [Microwave Surfing

This paper reported the successful application of a 13.56-MHz external RF field (600-800 W for 1-2 min) to induce efficient heating in aqueous suspensions of single-walled carbon nanotubes (SWNTs). When the SWNT solution was injected into tumors in live rabbits and the animals exposed to RF fields, the tumor cells were successfully destroyed with relatively little damage to surrounding tissues. The exact RF heating mechanism of such electrically small nanotubes is not yet understood.

Implantable Wireless Telemetry Boards for In Vivo Transocular Transmission

We report live animal studies that verify and quantify successful transocular transmission of data from a miniature low-power implant. To minimize damage, implantation within layers of the eye requires an ultrasmall device on a scale of just a few millimeters on each side and less than 500 mum in thickness. A high-frequency transmitter integrated circuit (IC) was designed, fabricated, and bonded onto a board containing an antenna, matching network components, and interconnects. The transmitter must achieve sufficient efficiency to draw minimal power from the limited onboard storage array while outputting a sufficiently large signal to overcome tissue-induced attenuation. Two different versions of the system were developed, one using a low-temperature co-fired ceramic material for the substrate and the other using silicon. Animal studies performed using live rabbits followed by empirical measurements verified the feasibility of a wireless telemetry scheme for a low-power miniature ocular implant.

Trans-Scleral Permeability of Oregon Green 488®

The aim of this study was to determine the scleral permeability of a commercially available version of 2',7'-difluorofluorescein (OG) and compare it to that of sodium fluorescein (NaF). Both in vitro and in vivo experiments were performed. For the ex vivo experiment, a Lucite block perfusion chamber with human donor sclera was used. Two hundred microliters (200 microL) of 2.5 mg/ml OG or NaF was placed in the donor chamber. The OG and NaF concentration that diffused across the sclera was measured every 2 h for 24 h by fluorometry, and the fluorescence in the sclera was examined by fluorescent microscopy. In vivo experiments consisted of live rabbits treated with a 0.2-mL subtenon injection of 7.5 mg/ml solution of either OG or NaF in the right eye. Intraocular fluorescence was measured by ocular fluorophotometry. The scleral permeability coefficient (K(trans)) of OG was 3.93 +/- 1.01 x 10(-7) cm/sec and that of NaF was 4.41 +/- 1.32 x 10(-7) cm/s. Both OG and NaF were visible throughout the sclera after 24 hours. Peak vitreous concentration after subtenon injection in rabbits was 6.48 +/- 2.65 ng/mL of OG at 2 min and 47.15 +/- 13.3 ng/mL of NaF at 10 min. OG was able to diffuse across the sclera and thus could be potentially useful as a fluorescent tag for intraocular drug delivery studies. However, its permeability was substantially less than that of NaF.