A Schlemm Canal Microstent for Intraocular Pressure Reduction in Primary Open-Angle Glaucoma and Cataract: The HORIZON Study.

OBJECTIVE: To compare cataract surgery with implantation of a Schlemm canal microstent with cataract surgery alone for the reduction of intraocular pressure (IOP) and medication use after 24 months. DESIGN: Prospective, multicenter, single-masked, randomized controlled trial. PARTICIPANTS: Subjects with concomitant primary open-angle glaucoma (POAG), visually significant cataract, and washed-out modified diurnal IOP (MDIOP) between 22 and 34 mmHg. METHODS: Subjects were randomized 2:1 to receive a single Hydrus Microstent (Ivantis, Inc, Irvine, CA) in the Schlemm canal or no stent after uncomplicated phacoemulsification. Comprehensive eye examinations were conducted 1 day, 1 week, and 1, 3, 6, 12, 18, and 24 months postoperatively. Medication washout and MDIOP measurement were repeated at 12 and 24 months. MAIN OUTCOME MEASURES: The primary and secondary effectiveness end points were the proportion of subjects demonstrating a 20% or greater reduction in unmedicated MDIOP and change in mean MDIOP from baseline at 24 months, respectively. Hypotensive medication use was tracked throughout the course of follow-up. Safety measures included the frequency of surgical complications and adverse events. RESULTS: A total of 369 eyes were randomized after phacoemulsification to Hydrus Microstent (HMS) and 187 to no microstent (NMS). At 24 months, unmedicated MDIOP was reduced by ≥20% in 77.3% of HMS group eyes and in 57.8% of NMS group eyes (difference = 19.5%, 95% confidence interval [CI] 11.2%-27.8%, P < 0.001). The mean reduction in 24-month unmedicated MDIOP was -7.6±4.1 mmHg (mean ± standard deviation) in the HMS group and -5.3±3.9 mmHg in the NMS group (difference = -2.3 mmHg; 95% CI, -3.0 to -1.6; P < 0.001). The mean number of medications was reduced from 1.7±0.9 at baseline to 0.3±0.8 at 24 months in the HMS group and from 1.7±0.9 to 0.7±0.9 in the NMS group (difference = -0.4 medications; P < 0.001). There were no serious ocular adverse events related to the microstent, and no significant differences in safety parameters between the 2 groups. CONCLUSIONS: This 24-month multicenter randomized controlled trial demonstrated superior reduction in MDIOP and medication use among subjects with mild-to-moderate POAG who received a Schlemm canal microstent combined with phacoemulsification compared with phacoemulsification alone.

Mechanism of action of bimatoprost, latanoprost, and travoprost in healthy subjects. A crossover study.

PURPOSE: To study the effects of 3 prostaglandin analogs, bimatoprost, latanoprost, and travoprost, on aqueous dynamics in the same subjects and to compare techniques of assessing outflow facility. DESIGN: Experimental study (double-masked, placebo-controlled, randomized paired comparison, 4-period crossover). PARTICIPANTS: Thirty healthy adult subjects. METHODS: Bimatoprost, latanoprost, travoprost, or a placebo was administered to the left eye once a day in the evening for 7 days, after a minimum 4-week washout period between each session. Tonographic outflow facility was measured by Schiøtz tonography and pneumatonography on day 7. On day 8, the aqueous humor flow rate and fluorophotometric outflow facility were measured by fluorophotometry. Uveoscleral outflow was calculated from the aqueous humor flow rate and outflow facility using the Goldmann equation. MAIN OUTCOME MEASURES: Facility of outflow, aqueous humor flow rate, intraocular pressure (IOP), and calculation of uveoscleral outflow. RESULTS: All medications lowered IOP relative to a placebo. None of the drugs affected aqueous humor production. All medications increased outflow facility compared with placebo when measured by Schiøtz and 2-minute pneumatonography (P< or =0.02); the apparent increase of outflow facility measured with fluorophotometry and 4-minute pneumatonography did not reach statistical significance. In contrast, uveoscleral outflow was significantly increased by all medications when calculated from 4-minute pneumatonography data, and fluorophotometry and Schiøtz data at higher episcleral venous pressures. The apparent increase found with 2-minute pneumatonography did not reach statistical significance. These differing results in the same patients indicate that differences in measurement techniques, and not differences in mechanism of action, explain previous conflicting published reports on the mechanism of action of the prostaglandins. CONCLUSIONS: Bimatoprost, latanoprost, and travoprost have similar mechanisms of action. All 3 drugs reduce IOP without significantly affecting the aqueous production rate. All drugs increase aqueous humor outflow, either by enhancing the pressure-sensitive (presumed trabecular) outflow pathway or by increasing the pressure-insensitive (uveoscleral) outflow, but the assessment of the amount of flow through each pathway depends upon the measurement technique.

Gonioscopically Guided Nonpenetrating Cyclodialysis Cleft Repair: A Novel Surgical Technique.

AIM: We present a novel surgical technique for repair of persistent and symptomatic cyclodialysis clefts refractory to conservative or minimally invasive treatment. BACKGROUND: Numerous surgical techniques have been described to close cyclodialysis clefts. The current standard approach involves intraocular repair of cyclodialysis clefts underneath a full-thickness scleral flap. TECHNIQUE: Our technique employs intraoperative use of a direct gonioscope to guide a nonpenetrating surgical repair. Subsequently, a significantly less invasive, nonpenetrating technique utilizing a partial-thickness scleral flap can be performed that reduces potential risks associated with intraocular surgery. The direct gonioscope is also used for confirmation of adequate surgical closure of the cyclodialysis cleft prior to completion of surgery. This technique has been successfully carried out to repair traumatic chronic cyclodialysis clefts associated with hypotony in two patients. There were no significant adverse events as a result of using this technique. CONCLUSION: The novel technique described increases the likelihood of successful and permanent repair of cyclodialysis clefts with resolution of symptoms associated with hypotony, through direct intraoperative visualization of the cleft. CLINICAL SIGNIFICANCE: Gonioscopically guided nonpenetrating cyclodialysis cleft repair offers significant benefits over previously described techniques. Advantages of our technique include gonioscopic cleft visualization, enabling accurate localization of the area requiring repair, and subsequent confirmation of adequate closure of the cleft. Using a partial-thickness scleral flap is also less invasive and reduces risks associated with treatment of this potentially challenging complication of ocular trauma. HOW TO CITE THIS ARTICLE: Rodrigues IAS, Shah B, Goyal S, Lim S. Gonioscopically Guided Nonpenetrating Cyclodialysis Cleft Repair: A Novel Surgical Technique. J Curr Glaucoma Pract 2017;11(1):31-34.

Aqueous outflow facility after phacoemulsification with or without goniosynechialysis in primary angle closure: a randomised controlled study.

BACKGROUND: Goniosynechialysis (GSL) to remove peripheral anterior synechiae (PAS) alongside standard cataract surgery has potential theoretical advantages, Published randomised trials, however, have not shown conclusive functional benefits and aqueous outflow changes following GSL are unknown. This study aimed to compare electronic Shiøtz tonographic aqueous outflow facility (TOF) following phacoemulsification with or without GSL in patients with primary angle closure (PAC) and PAC glaucoma. Secondary outcomes were changes in intraocular pressure (IOP) and use of glaucoma medications. METHODS: Prospective randomised pilot study of 26 patients on glaucoma medication, with ≥90° PAS and significant lens opacity. Patients were randomised 1:1 to receive phacoemulsification with intraocular lens (IOL) implantation only (phaco) or phacoemulsification with IOL plus GSL (phaco-GSL). RESULTS: Fourteen patients were randomised to phaco-GSL and 12 to phaco alone. TOF increased with phaco-GSL from 0.099±0.07 µL/min/mm Hg to 0.194±0.07, µL/min/mm Hg, p=0.0006, while the phaco group showed no significant change. IOP reduced in both groups, but reduced significantly more following phaco-GSL (46.0%) compared with phaco alone (27.6%, p=0.04). Medication use and extent of PAS only reduced with phaco-GSL, from 0.923±0.86 to 0.384±0.18 medications, p=0.0279, and from 249.2±83.4 to 110.8±53.9° PAS, 6 months postoperatively. No serious adverse events occurred in either group. CONCLUSIONS: Eyes randomised to both surgical groups had similar and good outcomes at 6 months in this pilot study. However, only eyes undergoing GSL combined with standard phacoemulsification had significantly increased TOF, reduced glaucoma medication dependence and PAS postoperatively. GSL should therefore be considered in such patients. TRIAL REGISTRATION NUMBER: NCT00719290, Results.

Increased crystalline lens thickness and phacomorphic glaucoma in patients with Fanconi anemia.

We describe 2 siblings with Fanconi anemia (FA). One developed phacomorphic glaucoma, and both had increased crystalline lens thickness, features that have not been reported in patients with FA. The possible pathogenesis and clinical implications of the findings are discussed.

The Pathogenesis of Raised Intraocular Pressure in Uveitis.

AIM: To analyze current understanding of the factors that contribute to raised intraocular pressure (IOP) in patients with uveitis. METHODS: A pubmed literature review was carried out using words including "uveitic glaucoma", "IOP AND uveitis", "ocular hypertension AND uveitis", "inflammation AND glaucoma", "aqueous dynamics" AND "glaucoma/uveitis". RESULTS: Of the two studies looking at the aqueous dynamics in experimentally induced uveitis, both found aqueous flow decreased acutely, and one found that uveoscleral outflow increased. This is likely to reflect the types of uveitis that present acutely with hypotony. A study examining patients with Fuch's heterochromic cyclitis found no difference in aqueous flow or uveoscleral outflow. No studies have examined aqueous dynamics in types of uveitis that present with acutely raised IOP. Levels of prostaglandins rise in acute uveitis, which has been shown to increase uveoscleral and trabecular outflow, without affecting aqueous flow. Studies have demonstrated that raised levels of trabecular protein reduce trabecular outflow. Steroid treatment, inflammatory cells, free radicals and enzymes are also likely to contribute to the development of raised pressure. When considering the impact of the pathogenesis of raised pressure in uveitis on its treatment, prostaglandins may provide good intraocular pressure control, but there are concerns regarding their theoretical ability to worsen the inflammatory response in uveitis. Studies have not conclusively proven this to be the case. Surgical success rates vary, but trabeculectomy plus an antimetabolite, deep sclerectomy plus an antimetabolite, and Ahmed valve surgery have been used. CONCLUSIONS: Uveitic glaucoma is caused by a number of different diseases, some of which present with acute hypotony, others with acutely raised IOP, and others which demonstrate an increase in IOP over time. Further studies should be carried out to examine the differing pathogenesis in these types of diseases, and to establish the best treatment options.

Accuracy of intraocular pressure measurements in new zealand white rabbits.

PURPOSE: Rabbits are commonly used for the evaluation of drugs and surgery to lower intraocular pressure (IOP). The accuracy of intraocular pressure measurement is therefore critical in the analysis of data and subsequent extrapolation to humans. The purpose of this study was to establish the most reliable technique, from several currently available methods, of measuring IOP in New Zealand White rabbits. METHODS: The IOPs of 11 healthy New Zealand White rabbits were measured with a fluid-filled pressure transducer system that was connected to the anterior chamber of each animal so that the IOP could be varied by altering the height of a bottle of balanced salt solution. Intraocular pressures were recorded over a range of 50 to 0 mm Hg by the transducer system, and comparative measurements at the same pressures were performed with the Tonopen XL (Mentor, Norwell, MA), the Perkins handheld applanation tonometer (Clement Clarke, Harlow, UK), and the Ocular Blood Flow (OBF) pneumatonometer (OBF Laboratories, Wiltshire, UK). RESULTS: All three tonometers underestimated the true IOP, especially at higher pressures. Although the mean difference in actual and tonometric IOP was least in the Tonopen XL, there was a high degree of variability through the entire range of IOPs measured. The Perkins tonometer, although slightly less accurate than the Tonopen XL, was more consistent in measurement. The OBF pneumatonometer was the least-reliable estimate of IOP. CONCLUSIONS: All tonometers underestimate IOP, with increasing inaccuracy at higher pressures. The Perkins applanation tonometer was the most reliable for measuring IOP in the range of 0 to 50 mm Hg in New Zealand White rabbits.

Corneal endothelial cell damage from glaucoma drainage device materials.

PURPOSE: To compare the level of endothelial damage caused by contact with materials used in contemporary glaucoma drainage devices and a phosphorylcholine polymer-coated PMMA (PC-PMMA). METHODS Standard-sized discs of silicone, PMMA (polymethylmethacrylate), and PC-PMMA (n = 6) were gently lowered onto cultured bovine corneal endothelial (BCE) monolayers using a vacuum suction device. A 2.4-g stainless steel cloning ring weight was then placed on top of each disc. The weights and discs were removed using a vacuum suction device and forceps after 5 minutes of contact. A 0.4% trypan blue solution was used to stain the cell monolayer to visualize the area of cell damage. The total area of damage in each well (including the area stripped of cells) was measured using an image processor and expressed as a percentage of the total disc area to derive a damage coefficient for each material. Damage coefficients for different materials were compared using Bonferroni corrected analysis of variance (ANOVA). RESULTS: Percentage of areas of damage (mean +/- SD) after standardized contact were as follows: PMMA, 5.95 +/- 4.60%; silicone, 3.08 +/- 2.68%; PC-PMMA, 0.15 +/- 0.25%. PMMA caused marked endothelial cell damage. PC-PMMA discs produced a significantly lower level (p = 0.04) of endothelial cell trauma. CONCLUSION: Our results suggest that PC coating technology may be effective in reducing the rate of corneal endothelial failure following GDD implantation.

Effect of primary selective laser trabeculoplasty on tonographic outflow facility: a randomised clinical trial.

PURPOSE: To investigate the effect of 180° versus 360° primary selective laser trabeculoplasty (SLT) on tonographic outflow facility and intraocular pressure (IOP). DESIGN: Prospective, single masked randomised clinical trial. PARTICIPANTS: Patients with untreated primary open angle glaucoma or ocular hypertension both with IOP > 21-35 mmHg. METHODS: 40 patients randomly treated with 180° or 360° SLT after baseline tonographic outflow facility (electronic Schiøtz tonography) and IOP measurements were repeated after 1 month. One eye from each patient was randomly selected for analysis. Eight untreated eyes were included as a control group. MAIN OUTCOME MEASURES: Tonographic outflow facility and IOP difference. Responders were defined as having at least a 20% reduction in IOP. RESULTS: Three patients were excluded due to poor tonography. There were 18 eyes in the 180° group and 19 eyes in the 360° group. Tonographic outflow facility increased significantly (180° p = 0.003, 360° p = 0.005) and IOP decreased significantly (180° and 360° p < 0.001) from baseline. There were no significant differences between the two groups as regards the increase in tonographic outflow facility (180° group 37.5%, 360° group 41%, p = 0.23) and decrease in IOP (180° group 24%, 360° group 35%, p = 0.35). There were similar number of responders in 180° group (72%) as compared to 360° group (89.5%, p = 0.23). Tonographic outflow facility and IOP did not change significantly from baseline in the control group (tonographic outflow facility: 8% increase p = 0.48, IOP: 4% decrease p = 0.33). CONCLUSIONS: Primary SLT significantly increased the tonographic outflow facility and decreased IOP in patients with primary open angle glaucoma and ocular hypertension but no statistically significant differences were found between the 360° and 180° groups. The level of IOP reduction due to primary SLT treatment could not be explained by the increase in tonographic outflow facility alone. Clinical trial registration ISRCTN66330584, Current Controlled Trials. 1/11/2006.