D, and by Poole et al., [15] wherein sodium hyaluronate was injected to treat retinal detachments. Einmahl et al., [14] observed that poly (ortho ester) injection in the SCS caused no clinical complications except some slight choroidal pigmentation and presence of vacuoles in the SCS. Poole et al., [15] observed slight bleeding and inflammation at the site of injection, which disappeared within 3 weeks. Olsen et al. [16] evaluated the safety of a novel cannula system for MedChemExpress BIBS39 delivery in the SCS by monitoring histopathology and retinal and choroidal blood flow in monkeys and pigs and observed minor tissue injury at the site of injection. More 
recently, Patel et al. [17] developed and evaluated a minimally invasive strategy using a novel hollow microneedle system to study the ex vivo suprachoroidal distribution of sulforhodamine B dye and particles ranging in size from 20 to 1000 nm. Suprachoroidal delivery is minimally invasive and might be safer because it does not require entry into the vitreous, thereby potentially protecting retina from any injection related damage. Even though suprachoroidal delivery is being evaluated for effective treatment of posterior segment disorders, there are no reports comparing it to periocular injections. Further, there are limited investigations comparing suprachoroidal and intravitreal routes of delivery, that too for a protein drug but not small molecules [18]. Since choroid vessels have high blood flow, it is generally perceived that drug molecules can clear very rapidly. Therefore, a direct comparison of different routes of drug administration will help establish the relative advantage of suprachoroidal delivery. We used a non-invasive ocular fluorophotometry technique to study the distribution of NaF following different routes of injection. Following periocular injections, a few pharmacokinetics studies have been conducted using ocular fluorophotometry for small molecules such as NaF [19] and oregon green abeled triamcinolone acetonide [20] and macromolecules such as high molecular weight FITC-dextran (40 kDa and 70 kDa) [21]. Traditional methods of evaluating ocular pharmacokinetics are invasive and costly. Sacrificing animals at multiple time points followed by eye enucleation and isolation of different ocular tissues makes the process tedious and time consuming. Further, changes in drug location and concentration can occur during tissue 
extraction. In comparison, ocular fluorophotometry is a non-invasive technique, which does not affect ocular tissues and allows time courseevaluations in the same animal in different ocular tissues using a single scan. In this study, we determined the delivery and pharmacokinetics of NaF injected in suprachorodial space of rats and compared it with intravitreal and posterior subconjunctival 1527786 injections using ocular fluorophotometry. NaF is a rational choice for in vivo fluorophotometry because of its safety [22], high absorptivity, and fluorescence yield [23]. Further, the molecular weight of NaF (376 Da) is similar to many antimicrobial agents and steroids administered to the eye for the treatment of ocular disorders.Human parathyroid hormone-(1-34) web Materials and Methods MaterialsSodium fluorescein (NaF) used in this study was purchased from Sigma-Aldrich (St. Louis, MO).Ethics StatementAll animals were treated according to the Association for Research in Vision and Ophthalmology (ARVO) statement for the Use of Animals in Ophthalmic and Vision Research. Animal protocols followed during this study wer.D, and by Poole et al., [15] wherein sodium hyaluronate was injected to treat retinal detachments. Einmahl et al., [14] observed that poly (ortho ester) injection in the SCS caused no clinical complications except some slight choroidal pigmentation and presence of vacuoles in the SCS. Poole et al., [15] observed slight bleeding and inflammation at the site of injection, which disappeared within 3 weeks. Olsen et al. [16] evaluated the safety of a novel cannula system for delivery in the SCS by monitoring histopathology and retinal and choroidal blood flow in monkeys and pigs and observed minor tissue injury at the site of injection. More recently, Patel et al. [17] developed and evaluated a minimally invasive strategy using a novel hollow microneedle system to study the ex vivo suprachoroidal distribution of sulforhodamine B dye and particles ranging in size from 20 to 1000 nm. Suprachoroidal delivery is minimally invasive and might be safer because it does not require entry into the vitreous, thereby potentially protecting retina from any injection related damage. Even though suprachoroidal delivery is being evaluated for effective treatment of posterior segment disorders, there are no reports comparing it to periocular injections. Further, there are limited investigations comparing suprachoroidal and intravitreal routes of delivery, that too for a protein drug but not small molecules [18]. Since choroid vessels have high blood flow, it is generally perceived that drug molecules can clear very rapidly. Therefore, a direct comparison of different routes of drug administration will help establish the relative advantage of suprachoroidal delivery. We used a non-invasive ocular fluorophotometry technique to study the distribution of NaF following different routes of injection. Following periocular injections, a few pharmacokinetics studies have been conducted using ocular fluorophotometry for small molecules such as NaF [19] and oregon green abeled triamcinolone acetonide [20] and macromolecules such as high molecular weight FITC-dextran (40 kDa and 70 kDa) [21]. Traditional methods of evaluating ocular pharmacokinetics are invasive and costly. Sacrificing animals at multiple time points followed by eye enucleation and isolation of different ocular tissues makes the process tedious and time consuming. Further, changes in drug location and concentration can occur during tissue extraction. In comparison, ocular fluorophotometry is a non-invasive technique, which does not affect ocular tissues and allows time courseevaluations in the same animal in different ocular tissues using a single scan. In this study, we determined the delivery and pharmacokinetics of NaF injected in suprachorodial space of rats and compared it with intravitreal and posterior subconjunctival 1527786 injections using ocular fluorophotometry. NaF is a rational choice for in vivo fluorophotometry because of its safety [22], high absorptivity, and fluorescence yield [23]. Further, the molecular weight of NaF (376 Da) is similar to many antimicrobial agents and steroids administered to the eye for the treatment of ocular disorders.Materials and Methods MaterialsSodium fluorescein (NaF) used in this study was purchased from Sigma-Aldrich (St. Louis, MO).Ethics StatementAll animals were treated according to the Association for Research in Vision and Ophthalmology (ARVO) statement for the Use of Animals in Ophthalmic and Vision Research. Animal protocols followed during this study wer.