Fibrillin-1 mutant mouse captures defining features of human primary open glaucoma including anomalous aqueous humor TGF beta-2.

Primary open angle glaucoma (POAG) features an optic neuropathy, elevated aqueous humor (AH) TGFß2, and major risk factors of central corneal thickness (CCT), increasing age and intraocular pressure (IOP). We examined Tight skin (Tsk) mice to see if mutation of fibrillin-1, a repository for latent TGFß, is associated with characteristics of human POAG. We measured: CCT by ocular coherence tomography (OCT); IOP; retinal ganglion cell (RGC) and optic nerve axon counts by microscopic techniques; visual electrophysiologic scotopic threshold responses (STR) and pattern electroretinogram (PERG); and AH TGFß2 levels and activity by ELISA and MINK epithelial cell-based assays respectively. Tsk mice had open anterior chamber angles and compared with age-matched wild type (WT) mice: 23% thinner CCT (p < 0.003); IOP that was higher (p < 0.0001), more asymmetric (p = 0.047), rose with age (p = 0.04) and had a POAG-like frequency distribution. Tsk mice also had RGCs that were fewer (p < 0.04), declined with age (p = 0.0003) and showed increased apoptosis and glial activity; fewer optic nerve axons (p = 0.02); abnormal axons and glia; reduced STR (p < 0.002) and PERG (p < 0.007) visual responses; and higher AH TGFß2 levels (p = 0.0002) and activity (p = 1E-11) especially with age. Tsk mice showed defining features of POAG, implicating aberrant fibrillin-1 homeostasis as a pathogenic contributor to emergence of a POAG phenotype.

Organogenesis and distribution of the ocular lymphatic vessels in the anterior eye.

Glaucoma surgeries, such as trabeculectomy, are performed to lower intraocular pressure to reduce risk of vision loss. These surgeries create a new passage in the eye that reroutes the aqueous humor outflow to the subconjunctival space, where the fluid is presumably absorbed by the conjunctival lymphatics. Here, we characterized the development and function of the ocular lymphatics using transgenic lymphatic reporter mice and rats. We found that the limbal and conjunctival lymphatic networks are progressively formed from a primary lymphatic vessel that grows from the nasal-side medial canthus region at birth. This primary lymphatic vessel immediately branches out, invades the limbus and conjunctiva, and bidirectionally encircles the cornea. As a result, the distribution of the ocular lymphatics is significantly polarized toward the nasal side, and the limbal lymphatics are directly connected to the conjunctival lymphatics. New lymphatic sprouts are produced mainly from the nasal-side limbal lymphatics, posing the nasal side of the eye as more responsive to fluid drainage and inflammatory stimuli. Consistent with this polarized distribution of the ocular lymphatics, a higher drainage efficiency was observed in the nasal side than the temporal side of the eye when injected with a fluorescent tracer. In contrast, blood vessels are evenly distributed at the anterior surface of the eyes. Also, we found that these distinct vascular distribution patterns were conserved in human eyes. Together, our study demonstrated that the ocular surface lymphatics are more densely present in the nasal side and uncovered the potential clinical benefits in selecting the nasal side as a glaucoma surgery site to improve fluid drainage.

Micropulse Transscleral Diode Laser Cyclophotocoagulation in Refractory Glaucoma: Short-Term Efficacy, Safety, and Impact of Surgical History on Outcomes.

PURPOSE: To assess the short-term efficacy and safety of micropulse transscleral diode laser cyclophotocoagulation (MP-TSCPC) in the management of refractory glaucoma and to compare outcomes based on prior glaucoma surgeries. DESIGN: Retrospective analysis. PARTICIPANTS: Patients with refractory glaucoma who underwent MP-TSCPC at a single institution by 1 of 4 surgeons. METHODS: Chart review of cases of MP-TSCPC using the Iridex Cyclo G6 (Mountain View, CA) laser with standard parameters and laser duration at the discretion of each treating physician. MAIN OUTCOME MEASURES: Probability of postoperative success was estimated by the Kaplan-Meier method. Success parameters included intraocular pressure (IOP) 6 to 21 mmHg with or without topical antihypertensive therapy, 20% or more IOP reduction from baseline for any 2 consecutive visits after 3 postoperative months, and no subsequent glaucoma surgery. RESULTS: One hundred sixteen eyes of 116 patients (mean age, 65.8±16.9 years) were included. Baseline IOP was 22.2±7.9 mmHg, and mean postoperative follow-up time was 6.3±3.4 months (range, 3-12 months.) Postoperative IOP at the final follow up was 15.3±6.6 mmHg (P < 0.01), corresponding to a reduction of approximately 6.9 mmHg (31.1%). Most eyes (66.4%) underwent at least 6 months of follow-up. Short-term probability of success was 93.1% at 3 months and 74.3% at 6 months. Eyes that had undergone prior traditional glaucoma surgery (trabeculectomy, tube shunt, excessive pressure-regulating shunt system miniature glaucoma shunt [Alcon, Fort Worth, TX], or a combination thereof) demonstrated a higher probability of success (67.6%) compared with eyes that had not (41.4%; P = 0.014). The most common complications were decline in best-corrected visual acuity (7.8%) and hypotony (1.7%). CONCLUSIONS: Micropulse transscleral diode laser cyclophotocoagulation has a significant short-term ocular hypotensive effect and favorable safety profile in eyes with refractory glaucoma. The probability of successful outcome was greater in eyes that had undergone prior traditional glaucoma surgery.

Deep tissue analysis of distal aqueous drainage structures and contractile features.

Outflow resistance in the aqueous drainage tract distal to trabecular meshwork is potentially an important determinant of intraocular pressure and success of trabecular bypass glaucoma surgeries. It is unclear how distal resistance is modulated. We sought to establish: (a) multimodal 2-photon deep tissue imaging and 3-dimensional analysis of the distal aqueous drainage tract (DT) in transgenic mice in vivo and ex vivo; (b) criteria for distinguishing the DT from blood and lymphatic vessels; and (c) presence of a DT wall organization capable of contractility. DT lumen appeared as scleral collagen second harmonic generation signal voids that could be traced back to Schlemm's canal. DT endothelium was Prox1-positive, CD31-positive and LYVE-1-negative, bearing a different molecular signature from blood and true lymphatic vessels. DT walls showed prominent filamentous actin (F-actin) labeling reflecting cells in a contracted state. F-actin co-localized with mesenchymal smooth muscle epitopes of alpha-smooth muscle actin, caldesmon and calponin, which localized adjacent and external to the endothelium. Our findings support a DT wall organization resembling that of blood vessels. This reflects a capacity to contract and support dynamic alteration of DT caliber and resistance analogous to the role of blood vessel tone in regulating blood flow.

Aqueous Angiography-Mediated Guidance of Trabecular Bypass Improves Angiographic Outflow in Human Enucleated Eyes.

PURPOSE: To assess the ability of trabecular micro-bypass stents to improve aqueous humor outflow (AHO) in regions initially devoid of AHO as assessed by aqueous angiography. METHODS: Enucleated human eyes (14 total from 7 males and 3 females [ages 52-84]) were obtained from an eye bank within 48 hours of death. Eyes were oriented by inferior oblique insertion, and aqueous angiography was performed with indocyanine green (ICG; 0.4%) or fluorescein (2.5%) at 10 mm Hg. With an angiographer, infrared and fluorescent images were acquired. Concurrent anterior segment optical coherence tomography (OCT) was performed, and fixable fluorescent dextrans were introduced into the eye for histologic analysis of angiographically positive and negative areas. Experimentally, some eyes (n = 11) first received ICG aqueous angiography to determine angiographic patterns. These eyes then underwent trabecular micro-bypass sham or stent placement in regions initially devoid of angiographic signal. This was followed by fluorescein aqueous angiography to query the effects. RESULTS: Aqueous angiography in human eyes yielded high-quality images with segmental patterns. Distally, angiographically positive but not negative areas demonstrated intrascleral lumens on OCT images. Aqueous angiography with fluorescent dextrans led to their trapping in AHO pathways. Trabecular bypass but not sham in regions initially devoid of ICG aqueous angiography led to increased aqueous angiography as assessed by fluorescein (P = 0.043). CONCLUSIONS: Using sequential aqueous angiography in an enucleated human eye model system, regions initially without angiographic flow or signal could be recruited for AHO using a trabecular bypass stent.

Endoscopic Cyclophotocoagulation and Pars Plana Ablation (ECP-plus) to Treat Refractory Glaucoma.

PURPOSE: To report clinical outcomes after pars plana endoscopic cyclophotocoagulation of the ciliary processes and pars plana (ECP-plus), a novel treatment for refractory glaucoma. DESIGN: Retrospective, noncomparative interventional case series. SETTING: multicenter tertiary referral academic and clinical practice. STUDY POPULATION: fifty-three eyes of 53 consecutive subjects undergoing ECP-plus who had uncontrolled intraocular pressure (IOP) despite prior glaucoma surgeries and maximally tolerated medical therapy. OBSERVATION PROCEDURE: retrospective analysis of clinical data after ECP-plus and pars plana vitrectomy. MAIN OUTCOME MEASURES: primary outcome was IOP at 6 and 12 months. Secondary outcomes were number of glaucoma medications and postoperative complications. RESULTS: Diagnoses were primary open-angle glaucoma (32%), chronic angle-closure glaucoma (26%), and secondary open-angle glaucoma (OAG, 42%); 50/53 of subjects had 6 months' and 28/53 had 12 months' follow-up data. Preoperative IOP was 27.9±7.5 mm Hg (mean±SD). Postoperative IOP at 6 mo was 10.2±5.6 and at 12 mo was 10.7±5.2 lower than preoperative levels (all P<0.0001). Cumulative treatment success was 81% at 6 mo and 78% at 12 mo. Number of medications fell from 3.4±1.2 pretreatment to 0.8±1.0 at 1 to 6 mo and 0.7±1.2 at 12 mo postoperatively (all P<0.0001). Complications in the initial postoperative period (<3 mo) were hypotony (3/53, 6%), fibrinous uveitis (2/53, 4%), and cystoid macular edema without hypotony (CME; 4/53, 6%). Complications beyond 6 mo occurred in 8/50 (16%) subjects as hypotony (4/50, 8%), choroidal detachment (4/50, 3 with IOP<5 and 1 with IOP≥5; 8%), CME without hypotony (3/50, 6%), and failed corneal graft (1/50, 2%). CONCLUSIONS: The mean IOP was lowered by at least 61% after ECP-plus and IOP lowering was sustained over the follow-up period. Fewer glaucoma medications were needed. Complication rates were comparable with or slightly higher than anterior endoscopic cyclophotocoagulation and acceptable given the refractory nature of disease being treated.