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Background and Purpose: The prostamides (prostaglandin-ethanolamides) and prostaglandin (PG) glyceryl esters are biosynthesized by COX-2 from the respective endocannabinoids anandamide and 2-arachidonyl glycerol. Agonist studies suggest that their pharmacologies are unique and unrelated to prostanoid receptors. This concept was further investigated using antagonists. Experimental Approach: The isolated feline iris was used as a key preparation, where prostanoid FP receptors and prostamide activity co-exist. Activity at human recombinant FP and other prostanoid receptors was determined using stable transfectants. Key Results: In the feline iris, AGN 204396 produced a rightward shift of the dose-response curves for prostamide F2α and the prostamide F2α analog bimatoprost but did not block the effects of PGF2α and synthetic FP receptor agonists. Studies on human recombinant prostanoid receptors confirmed that AGN 204396 did not behave as a prostanoid FP receptor antagonist. AGN 204396 exhibited no antagonism at DP and EP1-4, but was a highly effective TP receptor antagonist. Contrary to expectation, the FP receptor antagonist AL-8810 efficaciously contracted the cat iris. AGN 204396 did not affect AL-8810 induced contractions, demonstrating that AL-8810 and AGN 204396 are pharmacologically distinct. Unlike AL-8810, the ethylamide derivate of AL-8810 was not an agonist. Al-8810 did not block prostamide F2α activity. Finally, AGN 204396 did not block PGE2-glyceryl ester activity. Conclusions and Implications: The ability of AGN 204396 to selectively block prostamide responses suggests the existence of prostamide sensitive receptors as entities distinct from receptors recognizing PGF2α and PGE2-glyceryl ester. British Journal of Pharmacology (2007) 150, 342–352. doi:10.1038/sj.bjp.0706989

PURPOSE The prostaglandin F2alpha (PGF2α) analogue bimatoprost lowers intraocular pressure (IOP) by increasing uveoscleral outflow at doses shown to elicit redness of the eye. With the aim to enhance the IOP-lowering effect of bimatoprost we studied NCX 470 [(S,E)-1-((1R,2R,3S,5R)-2-((Z)-7-(ethylamino)-7-oxohept-2-enyl)-3,5-dihydroxycyclopentyl)-5-phenylpent-1-en-3-yl 6-(nitrooxy)hexanoate], a dual-acting compound combining bimatoprost with nitric oxide (NO) known to mainly act via relaxation of trabecular meshwork and Schlemm's canal. METHODS New Zealand white rabbits with transient hypertonic saline-induced IOP elevation (tOHT-rabbits), cynomolgus monkeys with laser-induced ocular hypertension (OHT-monkeys), and normotensive dogs (ONT-dogs) were used. The levels of NCX 470, bimatoprost, and bimatoprost acid were determined in aqueous humor (AH), cornea (CR), and iris/ciliary body (ICB) by liquid chromatography-mass spectrometry/mass (LC-MS/MS), while cGMP in AH and ICB was monitored using an enzyme immunoassay (EIA) kit in pigmented Dutch Belted rabbits. RESULTS NCX 470 (0.14%, 30 μL) lowered IOP in tOHT-rabbits with an E(max) of -7.2 ± 2.8 mm Hg at 90 minutes. Bimatoprost at equimolar dose (0.1%, 30 μL) was noneffective in this model. NCX 470 (0.042%, 30 μL) was more effective than equimolar (0.03%, 30 μL) bimatoprost in ONT-dogs (IOP change, -5.4 ± 0.7 and -3.4 ± 0.7 mm Hg, respectively, P < 0.05) and in OHT-monkeys (IOP change, -7.7 ± 1.4 and -4.8 ± 1.7 mm Hg, respectively, P < 0.05) at 18 hours post dosing. NCX 470 (0.042%, 30 μL) or bimatoprost (0.03%, 30 μL) resulted in similar bimatoprost acid exposure in AH, CR, and ICB while cGMP was significantly increased in AH and ICB at 18 and 24 hours after NCX 470 dosing. CONCLUSIONS NCX 470 lowers IOP more than equimolar bimatoprost in three animal models of glaucoma by activating PGF2α and NO/cGMP signaling pathways.

Connective tissue growth factor (CTGF) and Cyr61 (cysteine-rich angiogenic protein 61) are members of the CCN gene family that encode multifunctional, extracellular matrix-associated signaling proteins. Because the mechanism of action of certain anti-glaucoma drugs involves extracellular matrix remodeling of ocular ciliary muscle, with a resultant increase in drainage of aqueous humor from the eye, we compared the effects of three pharmacologically distinct ocular hypotensive agents on Cyr61 and CTGF gene expression. Thus, prostaglandin F2alpha (PGF2alpha) (FP receptor agonist), Butaprost (EP2 receptor agonist), and Bimatoprost (a prostamide) were compared. Using Affymetrix gene chip technology, we first identified that PGF2alpha dramatically up-regulated Cyr61 and CTGF mRNA expression in HEK 293/EBNA cells (hFP-HEK 293/EBNA). Northern blot further confirmed the Cyr61 and CTGF up-regulation is in a dose- and time-dependent manner. PGF2alpha-induced up-regulation of Cyr61 appeared to exclusively involve the Rho pathway, and up-regulation of CTGF was via multiple intracellular pathways. Because prostamide receptors are, to date, defined only at the pharmacological level, Bimatoprost effects on Cyr61 and CTGF were studied in the isolated feline iris sphincter preparation, a tissue highly responsive to prostamides. Both PGF2alpha and Bimatoprost up-regulated Cyr61 mRNA expression in the cat iris tissue. Only PGF2alpha up-regulated CTGF mRNA expression in the cat iris. Therefore, PGF2alpha and Bimatoprost appear to interact with different receptors populations in the cat iris, according to their markedly different effects on CTGF. Activation of prostaglandin EP2 receptors (Gs-coupled) also up-regulated Cyr61 but not CTGF mRNA expression in the isolated cat iris. Similar data were observed in human primary ciliary smooth muscle cells. Thus, despite quite different signal transduction pathways, FP receptor stimulation up-regulates CTGF and Cyr61. The prostamide analog Bimatoprost and an EP2-selective agonist affects only Cyr61.

Prostaglandin F(2 alpha) (PGF(2 alpha)) receptors are G-protein-coupled receptors consisting of two alternative mRNA splice variants, named FP(A) and FP(B). As compared with the FP(A) isoform, the FP(B) isoform lacks the last 46 amino acids of the carboxyl terminus and, therefore, represents a truncated version of the FP(A). We recently found (Pierce, K. L., Fujino, H., Srinivasan, D., and Regan, J. W. (1999) J. Biol. Chem. 274, 35944-35949) that stimulation of both isoforms with PGF(2 alpha) leads to activation of a Rho signaling pathway, resulting in tyrosine phosphorylation of p125 focal adhesion kinase, formation of actin stress fibers, and cell rounding. Although the activation of Rho and subsequent cell rounding occur at a similar rate for both isoforms, we now report that following the removal of PGF(2 alpha) the reversal of cell rounding is much slower for cells expressing the FP(B) isoform as compared with the FP(A) isoform. Thus, in HEK-293 cells that stably express the FP(A) isoform, the reversal of cell rounding appears to be complete after 1 h, whereas for FP(B)-expressing cells there is essentially no reversal even after 2 h. Similarly, the disappearance of stress fibers and dephosphorylation of p125 focal adhesion kinase following removal of agonist are much slower in FP(B)-expressing cells than in FP(A)-expressing cells. The mechanism of this differential reversal appears to involve a difference in receptor resensitization following the removal of agonist. Based upon whole cell radioligand binding, agonist-induced stimulation of inositol phosphate formation, and mobilization of intracellular Ca(2+), the FP(B) isoform resensitizes more slowly than the FP(A) isoform. These findings suggest that the carboxyl terminus of the FP(A) is critical for resensitization and that the slower resensitization of the FP(B) isoform leads to prolonged signaling. This differential signaling distinguishes the FP(A) and FP(B) receptor isoforms and could be important toward understanding the physiological actions of PGF(2 alpha).

Replacement of the carboxylic acid group of PGF(2alpha) with the non-acidic substituents hydroxyl (-OH) or methoxy (-OCH(3)) resulted in an unexpected activity profile. Although PGF(2alpha) 1-OH and PGF(2alpha) 1-OCH(3) exhibited potent contractile effects similar to 17-phenyl PGF(2alpha) in the cat lung parenchymal preparation, they were approximately 1000 times less potent than 17-phenyl PGF(2alpha) in stimulating recombinant feline and human FP receptors. In human dermal fibroblasts and Swiss 3T3 cells PGF(2alpha) 1-OH and PGF(2alpha) 1-OCH(3) produced no Ca(2+) signal until a 1 microM concentration was exceeded. Pretreatment of Swiss 3T3 cells with either 1 microM PGF(2alpha) 1-OH or PGF(2alpha) 1-OCH(3) did not attenuate Ca(2+) signal responses produced by PGF(2alpha) or fluprostenol. In the rat uterus, PGF(2alpha) 1-OH was about two orders of magnitude less potent than 17-phenyl PGF(2alpha) whereas PGF(2alpha) 1-OCH(3) produced only a minimal effect. Radioligand binding studies on cat lung parenchymal plasma membrane preparations suggested that the cat lung parenchyma does not contain a homogeneous population of receptors that equally respond to PGF(2alpha)1-OH, PGF(2alpha)1-OCH(3), and classical FP receptor agonists. Studies on smooth muscle preparations and cells containing DP, EP(1), EP(2), EP(3), EP(4), IP, and TP receptors indicated that the activity of PGF(2alpha) 1-OH and PGF(2alpha) 1-OCH(3) could not be ascribed to interaction with these receptors. The potent effects of PGF(2alpha) 1-OH and PGF(2alpha) 1-OCH(3) on the cat lung parenchyma are difficult to describe in terms of interaction with the FP or any other known prostanoid receptor.

The effects of leukotriene (LT) B4 and D4 on the motility of human peripheral blood neutrophils were investigated employing a novel analytical method. Using the under-agarose technique, migration distance and vectorial orientation of neutrophils in response to selected LT concentrations were determined with the aid of digital image processing. Neutrophil polarization induced by a chemotactic gradient was very apparent even at fields taken adjacent to the cell seeding well where little directional cell motility had occurred. Thus, cell polarization appeared to be the earliest response to chemoattractive LTs. Cell motility occurred in a dose-dependent manner to LTB4 according to determination of the leading edge. LTD4 produced similar effects on neutrophil polarization and motility, but these occurred only at very high concentrations. These data support the view that vectorial orientation is a prerequisite for directional migration of cells and it is also feasible that these are separately regulated events. Furthermore, our studies confirm that LTB4 and, to a much lesser extent, LTD4 are chemotactic for human peripheral blood neutrophils. J. Leukoc. Biol. 55: 201–208; 1994.

The effects of bimatoprost on aqueous humor dynamics were quantified in monkey eyes. Uveoscleral outflow was measured by the anterior chamber perfusion method, using FITC-dextran. Total outflow facility was determined by the two-level constant pressure method. Aqueous flow was measured with a scanning ocular fluorophotometer. Uveoscleral outflow was 0 . 9 6 ± 0 . 1 9 𝜇 L m i n − 1 in vehicle-treated eyes and 1 . 3 7 ± 0 . 2 7 𝜇 L m i n − 1 ( 𝑛 = 6 ; 𝑃 < . 0 5 ) in eyes that received bimatoprost 0.01% b.i.d. × 5 days. Bimatoprost had no effect on total outflow facility, which was 0 . 4 2 ± 0 . 0 5 𝜇 L m i n − 1 at baseline and 0 . 4 2 ± 0 . 0 4 𝜇 L m i n − 1 after bimatoprost treatment. Bimatoprost had no significant effect on aqueous humor flow. This study demonstrates that bimatoprost increases uveoscleral outflow but not total outflow facility or aqueous humor flow, indicating that it lowers intraocular pressure in ocular normotensive monkeys by a mechanism that exclusively involves uveoscleral outflow.

Dry eye disease (DED) is one of the most common and discomforting eye disorders. It has been defined as a multifactorial ocular surface disease more prevalent in women and the elderly. Dry eye disease is associated with symptoms of discomfort, visual disturbance, tear film instability, and inflammation of the ocular surface leading to potential damage to the ocular surface tissues.1 The proinflammatory milieu is characterized by increased levels of cytokines and chemokines in the tear film, cornea, and conjunctiva, and increased autoreactive T-cell infiltration of the conjunctival epithelium and sometimes lacrimal gland2–4; reviewed by Stern et al.5,6 Alteration of the tear film composition (mucins, lipids, proteins) and decreased volume lead to tear film abnormalities that contribute to the disease cycle. Subjecting mice to a controlled environment of desiccating stress results in ocular surface pathology reminiscent of human DED in patients in many respects.3,7–9 As of today, this model represents the best characterized animal model to study DED. Integrins are heterodimeric glycoproteins consisting of one α- and one β-subunit. Expressed on the cell surface of leukocytes, integrins have a role in their recruitment to sites of inflammation. The association of a specific α- and β-subunit determines the ligand specificity of the integrin. The α4 integrin subunit (CD49d) is a constituent of Very Late Antigen-4 (VLA-4, integrin a4b1, CD49d/CD29), and α4β7 (CD49d/CD103). In the case of integrin α4β1 the corresponding ligands are the immunoglobulin superfamily adhesion molecule vascular cell adhesion molecule 1 (VCAM-1) on vascular endothelial cells and the extracellular matrix glycoprotein fibronectin, which are responsible for the homing, trafficking, differentiation, priming, activation, and survival of integrin α4β1 expressing cells. Integrin α4β1 is expressed on lymphocytes, monocytes, macrophages, NK cells, and eosinophils. Integrin α4β7 and its corresponding ligand Mucosal Addressin Cell Adhesion Molecule-1 (MAdCAM) selectively regulate leukocyte trafficking to the gut and consequently are unlikely to be involved in the effects described herein. Natalizumab, an antibody directed against the α4 integrin subunit, has been shown to profoundly inhibit inflammation and improve clinical outcomes in multiple sclerosis10 and Crohn's disease,11 which also are T-cell–mediated diseases. Lifitegrast, a small molecule antagonist, directed against a different adhesion molecule (LFA-1, integrin αLβ2), has been shown to reduce corneal staining and improve symptoms when delivered topically to dry eye patients.12 Furthermore, a specific antagonist to integrin α4β1, BIO-8809, had been shown to decrease corneal fluorescein staining, conjunctival T-cell infiltrates, and TNFα expression in cornea and conjunctiva in a murine dry eye model.13 Taken together these considerations provided a rationale for further exploring the blockade of integrin α4 in an animal model of DED. In the current study, we tested the hypothesis using {"type":"entrez-nucleotide","attrs":{"text":"GW559090","term_id":"289141609","term_text":"GW559090"}}GW559090, a potent integrin α4 antagonist that previously had been clinically investigated in asthma patients by the oral inhalation route.14

PURPOSE. To investigate the ocular hypotensive effect of the prostanoid EP2 receptor agonist butaprost and to establish its mechanism of action. METHODS. All experiments were performed in cynomolgus monkeys after topical application of butaprost (0.1%). The effects of butaprost on aqueous humor flow were determined by fluorophotometry. Total outflow facility was measured by the two-level, constant-pressure perfusion method, and uveoscleral outflow was determined by perfusion of FITC-labeled dextran through the anterior chamber. Effects on ocular morphology were studied after tissue fixation with transcardial perfusion by paraformaldehyde and immersion fixation of the globe, in animals subjected to long-term treatment with butaprost. Conscious ocular normotensive monkeys and monkeys with unilateral ocular hypertension were used for intraocular pressure (IOP) studies. RESULTS. Butaprost had no significant effect on aqueous humor flow or total outflow facility in ocular normotensive monkeys. Uveoscleral outflow was significantly higher in the butaprost treated eyes than in vehicle treated eyes, 1.03 ± 0.20 vs. 0.53 ± 0.18 μL · min-1. After a 1-year treatment with butaprost, the morphology of the ciliary muscle was changed, showing increased spaces between ciliary muscle bundles and the apparent formation of new outflow channels. In many instances, changes were observed in the trabecular meshwork as well. Butaprost, in a single 0.1% dose, decreased IOP significantly in ocular normotensive monkeys and reduced IOP in laser-induced glaucomatous monkey eyes to the same level as that in the ocular normotensive contralateral eyes. CONCLUSIONS. The prostanoid EP2 receptor agonist butaprost appears to lower IOP by increasing uveoscleral outflow, according to both physiological and morphologic findings. Although the prostanoid EP2 receptor is structurally and functionally distinct from the FP receptor, the effects of EP2 and FP receptor stimulation on aqueous humor outflow are similar. Copyright © Association for Research in Vision and Ophthalmology.

The second annual ARVO/Pfizer Ophthalmic Research Institute conference was held Friday and Saturday, April 28 and 29, 2006, at the Fort Lauderdale Grande Hotel and Yacht Club, Fort Lauderdale, Florida. The conference, funded by The ARVO Foundation for Eye Research through a grant from Pfizer Ophthalmics, provided an opportunity to gather experts from within and outside ophthalmology to develop strategies to improve research and clinical care in areas of ophthalmology related to preventable vision loss and blindness. This year’s conference focused on aqueous humor outflow. A working group of 31 researchers on aqueous outflow, 8 scientists working on interests other than aqueous humor outflow but with expertise in areas relevant to the field, and 11 observers from ARVO, Pfizer, and clinical and basic ophthalmic research convened on April 28, 2006, to evaluate the current understanding of the aqueous humor outflow pathway. The goals were to compare similarities between ocular aqueous humor outflow and fluid flow in other tissues of the body, to critique conventional ideas, to identify the most important scientific questions, and to discuss strategies to answer these questions. The meeting format emphasized discussion and concentrated on questions within four general areas of outflow research: Session I: Conventional Outflow: Cell Function in the Aqueous Humor Outflow Pathway Session II: Conventional Outflow: Role of the Extracellular Matrix Session III: Uveoscleral Outflow: The Other Pathway Session IV: Normal Versus Primary Open Angle Glaucoma (POAG): What Is the Cause of Elevated Pressure? Each session began with a 10-minute overview by an outflow researcher followed by a 30-minute talk by one of the outside experts. Parallels between their fields of expertise and the eye were included in these talks. Invited outside experts covered several areas of research, including vascular endothelial cell biology (Peter Davies, PhD, University of Pennsylvania, Philadelphia), matricellular proteins (Paul Bornstein, MD, University of Washington, Seattle), renal and lymphatic biology (Donatscho Kerjaschki, MD, University of Vienna, Austria, and David Zawiega, PhD, Texas A & M University, College Station, Texas), oxidative damage mechanisms (James Mitchell, PhD, National Institutes of Health, Bethesda, Maryland), advanced glycation end-products and aging (Alan Stitt, PhD, Queens University, Belfast, Northern Ireland), cell adhesion (Benjamin Geiger, PhD, Weizmann Institute of Science, Rehovot, Israel), and cellular tight junctions (Eveline Schneeberger, MD, Massachusetts General Hospital, Boston, Massachusetts). The remainder of each session was used to discuss questions pertinent to the main topic and provided an opportunity for attendees to voice their opinions and work together to define questions that are still unanswered. The lively discussions were successful in defining old and new ideas that are essential to a better understanding of aqueous humor outflow. This conference summary highlights the ideas discussed and introduces areas that need further exploration.

1. The pharmacological activity of a novel series of 9,11-cyclic carbonate derivatives of prostaglandin F2 alpha (PGF2 alpha) was investigated in various isolated smooth muscle preparations possessing different prostanoid receptor subtypes as well as in human platelets. Since subdivision of thromboxane (TP-) receptors into vascular/smooth muscle and platelet subtypes is a controversial subject, our studies included a human smooth muscle preparation (myometrium) in addition to the widely used rat aorta and human platelets as TP-receptor preparations. 2. Two members of that series, AGN191976 and AGN192093 were found to be highly potent and selective thromboxane-mimetics. AGN191976 and AGN192093 contracted isolated tissues of the rat thoracic aorta with EC50 values of 0.32 +/- 0.08 and 1.30 +/- 0.53 nM, respectively. Both agonists were at least 10 times more potent than the benchmark TP-agonist, U-46619, in this preparation, whilst being at least 500 times less potent at other prostanoid receptors (DP, EP1, EP3, FP, IP) in vitro. 3. In human myometrial strips from pregnant and non-pregnant donors, both AGN191976 and AGN192093 were potent contractile agonists. The rank order of potency in myometrium of AGN191976 > AGN192093 > U-46619 correlated well with that in the rat aorta. In human platelet-rich plasma (PRP), however, AGN191976 had potent proaggregatory activity (EC50 = 16.3 +/- 1.4 nM), which is a TP-receptor-mediated event, whereas AGN192093 was a much weaker agonist (EC50 = 37.9 +/- 2.0 microM). AGN192093 did not behave as an antagonist in the platelets, since it did not antagonize platelet aggregation induced by ADP, arachidonic acid, U-46619 or AGN191976. In human washed platelets, the activity profile of AGN191976 (EC50 = 4.15 +/- 0.52 nM) and AGN192093 (no aggregation up to 10 microM) was similar to that obtained in PRP. 4. The involvement of TP-receptors was verified with the potent TP-antagonist, SQ29548. SQ29548 (0.1 microM in myometrium; 1 microM in aorta; 1 microM and 10 microM in platelets) antagonized responses to U-46619, AGN191976 and AGN192093 as expected. 5. In conclusion, AGN191976 and AGN192093, both 9,11-cyclic carbonate derivatives of PGF2 alpha, were found to be highly potent and selective thromboxane-mimetics in rat vascular and human myometrial smooth muscle. However, only AGN 191976 was a potent agonist at TP-receptors in human platelets. The differential activity of AGN192093 on TP-receptor-mediated events in platelets and smooth muscle provides further evidence for a subdivision of TP-receptors. AGN192093 appears to be a useful tool for the pharmacological distinction of TP-receptor subtypes.

The motility of isolated normal human peripheral blood eosinophils and neutrophils in response to exogenous leukotrienes B4 and D4 was examined by means of a modified under-agarose technique and a novel quantitative sampling strategy. Leukotriene D4 was a potent chemoattractant for eosinophils, with a significant threshold chemotactic effect evident at 10-10 M. The abolition of eosinophil chemotaxis by the potent and selective peptide-leukotriene-antagonist SK&F 104353 indicated the pharmacological specificity of the leukotriene D4-induced response. The chemokinetic response of eosinophils to leukotriene D4 generally did not differ significantly from spontaneous migratory activity of unstimulated cells. Leukotriene D4 did not, however, alter directed neutrophil motility until a very high concentration (10-5 M) was achieved, although significant neutrophil chemokinesis relative to unstimulated movement was observed over the tested concentration range. Directional emigration of both eosinophils and neutrophils was induced by leukotriene B4 at concentrations as low as 10-8 M. Analysis of leukocyte orientations provided evidence that chemokinetic responses were not being interpreted as indications of chemotactic behavior. These studies suggest that leukotriene D4 may behave as a potent and selective chemoattractant for human eosinophils at physiologically relevant concentrations. J. Leukoc. Biol. 55: 183–191; 1994.

PURPOSE. To investigate long-term changes in the anterior segment of primate eyes treated for one year with different prostaglandin agonists and a prostamide. The results were compared with those obtained after vehicle treatment and in untreated controls. METHODS. Sixteen young cynomolgus monkeys were unilaterally topically treated for 1 year with either bimatoprost 0.03% (prostamide), sulprostone 0.03% (EP3/EP1 agonist), AH13205 0.1% (EP2 agonist), or latanoprost 0.005% (FP agonist), which all lower IOP in this species at the doses applied. Four animals were treated with the vehicle only. In all cases the left eye was treated, the right eye remained untreated. Six monkeys served as untreated controls. Sections from 4 quadrants each of the circumference of the eyes of 16 drug-treated, 4 vehicle-treated and 6 untreated control animals were investigated qualitatively and quantitatively using light- and electronmicroscopy. The area of widened spaces between ciliary muscle bundles, the number of nerve fiber bundles at the muscle tips, and the width and length of the ciliary muscle were quantitated. RESULTS. The general morphology of the ciliary muscle and trabecular meshwork was normal in appearance and shape in all animals, whereas some localized morphologic changes were observed in the drug-treated animals. The changes were found to be similar in all four treatment groups. In the ciliary muscle, there was a significant increase in optically empty spaces between muscle bundles in the anterior portion of the longitudinal and the reticular ciliary muscle compared with untreated and vehicle-treated control animals. Within these spaces, significantly more myelinated nerve fiber bundles were found in drug-treated compared with normal control animals. Ultrastructurally the spaces were partly covered by endotheliallike cells which, in some areas, were in contact with the basement membrane of the microvasculature. In all treatment groups, there were also changes in the trabecular meshwork region. Significant regional differences among the different quadrants of the eyes and quantitative differences between treatment groups were observed. The ciliary epithelium had a normal appearance in all treatment groups. CONCLUSIONS. After one year of treatment with different prostaglandins and a prostamide, uveoscleral outflow pathways are enlarged and appear organized. Conventional outflow routes were also affected. Long-term treatment with AH13205, latanoprost, sulprostone, or bimatoprost also induces sprouting of nerve fibers. (Invest Ophthalmol Vis Sci. 2003;44:4419 ‐ 4426) DOI:10.1167/iovs.02-1281