A novel bilayered expanded polytetrafluoroethylene glaucoma implant creates a permeable thin capsule independent of aqueous humor exposure.

The purpose of these studies was to evaluate clinical, functional, and histopathological features of glaucoma drainage implants (GDIs) fabricated from novel, custom-tailored expanded polytetrafluoroethylene (ePTFE). Implants of matching footprints were fabricated from silicone (Control) and novel, bilayered ePTFE. ePTFE implants included: (a) one that inflated with aqueous humor (AH) (High), (b) one that inflated with a lower profile (Low), (c) an uninflated implant not connected to the anterior chamber (Flat), and (d) one filled with material that did not allow AH flow (Filled). All implants were placed in adult New Zealand White rabbits and followed over 1-3 months with clinical exams and intraocular pressure. The permeability of tissue capsules surrounding GDIs was assessed using constant-flow perfusion with fluoresceinated saline at physiologic flow rates. After sacrifice, quantitative histopathological measures of capsule thickness were compared among devices, along with qualitative assessment of cellular infiltration and inflammation. Capsular thickness was significantly reduced in blebs over ePTFE (61.4 ± 53 µm) versus silicone implants (193.6 ± 53 µm, p = .0086). AH exposure did not significantly alter capsular thickness, as there was no significant difference between High and Filled (50.9 ± 29, p = .34) implants. Capsules around ePTFE implants demonstrated permeability with steady-state pressure: flow relationships at physiologic flow rates and rapid pressure decay with flow cessation, while pressure in control blebs increased even at low flow rates and showed little decay. Perfused fluorescein dye appeared beyond the plate border only in ePTFE implants. ePTFE implants are associated with thinner, more permeable capsules compared to silicone implants simulating presently used devices.

Patient Acceptance of Sustained Glaucoma Treatment Strategies.

PURPOSE: To assess patient acceptance of different methods for delivering sustained-release, intraocular pressure (IOP)-lowering medications. METHODS: Electronic surveys were administered to 150 patients at 2 glaucoma clinics. Participants were questioned on their willingness to accept: (1) drug-eluting contact lenses, (2) ring inserts (3) punctal plugs, and (4) subconjunctival injections as alternatives to IOP-lowering eye drops based on various success levels. Multivariable logistic regression models determined the association between device type and treatment acceptance adjusting for age, sex, study site, cost burden of drops, and previous contact lens use. RESULTS: The majority (69%) of participants were 55 to 74 years of age, and white (65%), and half were female. The majority of participants would accept contacts (59%), rings (51%), plugs (57%), and subconjunctival injections (52%) if they obviated glaucoma surgery; fewer would accept these devices if they reduced (23% to 35%) or eliminated (27% to 42%) drops. Most participants would also accept contacts (56%), plugs (55%), and subconjunctival injections (53%) if they were more effective than eye drops, whereas only 47% would accept a ring; fewer would accept any device if it were equally or less effective than drops. Participants were also 36% (95% confidence interval=0.44-0.92; P=0.02) less likely to accept rings and 32% (95% confidence interval=0.47-0.98; P=0.04) less likely to accept subconjunctival injections as compared with contacts. CONCLUSION: Most glaucoma patients considered sustained drug-delivery modalities acceptable alternatives to IOP-lowering eye drops, but only when they were said to obviate surgery or demonstrate greater efficacy than eye drops.

Losartan Treatment Protects Retinal Ganglion Cells and Alters Scleral Remodeling in Experimental Glaucoma.

PURPOSE: To determine if oral losartan treatment decreases the retinal ganglion cell (RGC) death caused by experimental intraocular pressure (IOP) elevation in mice. METHODS: We produced IOP increase in CD1 mice and performed unilateral optic nerve crush. Mice received oral losartan, spironolactone, enalapril, or no drug to test effects of inhibiting angiotensin receptors. IOP was monitored by Tonolab, and blood pressure was monitored by tail cuff device. RGC loss was measured in masked axon counts and RGC bodies by ß-tubulin labeling. Scleral changes that could modulate RGC injury were measured including axial length, scleral thickness, and retinal layer thicknesses, pressure-strain behavior in inflation testing, and study of angiotensin receptors and pathways by reverse transcription polymerase chain reaction, Western blot, and immunohistochemistry. RESULTS: Losartan treatment prevented significant RGC loss (median loss = 2.5%, p = 0.13), while median loss with water, spironolactone, and enalapril treatments were 26%, 28% and 43%; p < 0.0001). The lower RGC loss with losartan was significantly less than the loss with spironolactone or enalapril (regression model p = 0.001; drug treatment group term p = 0.01). Both losartan and enalapril significantly lowered blood pressure (p< 0.001), but losartan was protective, while enalapril led to worse than water-treated RGC loss. RGC loss after crush injury was unaffected by losartan treatment (difference from control p = 0.9). Survival of RGC in cell culture was not prolonged by sartan treatment. Axonal transport blockade after 3 day IOP elevations was less in losartan-treated than in control glaucoma eyes (p = 0.007). Losartan inhibited effects of glaucoma, including reduction in extracellular signal-related kinase activity and modification of glaucoma-related changes in scleral thickness and creep under controlled IOP. CONCLUSIONS: The neuroprotective effect of losartan in mouse glaucoma is associated with adaptive changes in the sclera expressed at the optic nerve head.

Sequential episodes of perioperative ischemic optic neuropathy after hip surgery.

Perioperative ischemic optic neuropathy (ION) after nonocular surgery is a rare complication leading to permanent and often severe vision loss. Due in part to the low prevalence of this complication, there remains no reliable way to predict which patients will develop ION. We present a patient with sequential episodes of unilateral perioperative ION, both occurring after otherwise uncomplicated hip operations. Patients and physicians should be aware that perioperative ION after one surgery may increase the risk of ION after subsequent surgeries.