Anterior Trabecular Meshwork Research Articles

Delayed Topiramate-induced Bilateral Angle-Closure Glaucoma

To report a unique case of delayed topiramate-induced bilateral angle closure. A case report of a 40-year-old woman who experienced bilateral acute angle-closure glaucoma and induced myopia on a standard and consistent dose of topiramate for 262 days before the onset of symptoms. Initial and follow-up examination findings were reviewed. Initial examination revealed finger counting at one foot OU, intraocular pressures of 38 mm Hg OD and 37 mm Hg OS, and bilaterally closed angles with no view of anterior trabecular meshwork (Shaffer grade 0). Discontinuation of topiramate and administration of topical drops were able to break the attack. At 3 months of follow-up, the patient was 20/25 OU with deep angles open to the scleral spur (Shaffer grade III) and had intraocular pressures of 14 mm Hg in both the eyes. This case provides evidence of delayed bilateral angle closure from topiramate and raises questions as to the cellular mechanism of topiramate-induced angle closure, both immediate and delayed.

The Case

<div class="ftSection">An 18-month-old girl was evaluated for poor vision associated with displaced lenses. Her mother described the absence of “sparkle” in her eyes at 3 weeks of age with epiphora. Tear duct obstruction was suspected and nasal massage was recommended. At 10 months of age, mega-locornea was observed associated with phacodonesis in both eyes. At 14 months of age, bilateral lens subluxation and megalocornea were described at an examination under anesthesia with intraocular pressures of 22 mm Hg in the right eye and 18 mm Hg in the left eye with no disc cupping in both eyes. Examination found a healthy child with no systemic abnormalities. Brief fixation and follow in both eyes without nystagmus was observed. The corneal diameters measured 14.8 mm in the right eye and 14 mm in the left eye with deep anterior chambers. The irides were smooth without stromal collarettes; a significant circumferential pupillary ectropion was present in the right eye with striking thinning of the peripheral iris stroma that exposed the iris pigment epithelium. Both lenses were subluxated and mobile behind the irides inferiorly. Gonioscopy revealed bilateral circumferential insertion of the iris at the level of the anterior trabecular meshwork. The intraocular pressures were 25 mm Hg in the right eye and 27 mm Hg in the left eye and central disc cupping was confirmed. Corneal thickness was 745 μm in the right eye and 679 μm in the left eye. Following a trial of medication, surgery was recommended. </div>

Degree of angle closure and extent of peripheral anterior synechiae: an anterior segment OCT study

Aims:To evaluate the relationship between angle width as determined by anterior segment optical coherence tomography (AS-OCT) and the presence of peripheral anterior synechiae (PAS).Methods:This was a prospective observational case series...

Cirurgia filtrante não penetrante: conceito, técnicas e resultados

Recently, many discussions occurred concerning non-penetrating filtering surgery. Viscocanalostomy and deep sclerectomy with external trabeculectomy are the most practiced techniques. Their goal is to reduce intraocular pressure by enhancing the natural aqueous outflow, while reducing its resistance. Both techniques involve the removal of a deep scleral flap, the external wall of Schlemm's canal and corneal stroma behind the anterior trabecular meshwork and Descemet membrane, thus creating a scleral lake, where the aqueous humor remains until it is absorbed in many different ways. In viscocanalostomy, a high-molecular viscoelastic substance is injected into the ostia of Schlemm's canal in order to enlarge it and its collectors channels. In deep sclerectomy with external trabeculectomy, the inner wall of Schlemm's canal is removed with adjacent trabecular layers. Studies, both retrospective and prospective, demonstrated similar tensional results when compared to classical trabeculectomy, with fewer complications and better visual recovery after non-penetrating procedure. The aim of this study is to expose the non-penetrating surgery techniques, mechanism of action and results based on the analysis of published literature.

Study on the aqueous humor flow measured by fluorophotometry after argon laser trabeculoplasty.

We have investigated the variations in the aqueous humor flow (F) after argon laser photocoagulation (ALT) in the trabecular meshwork. The research has been done on 60 eyes with primary open angle glaucoma within initial stages. The argon laser trabeculoplasty was made around 360 degrees in anterior trabecular meshwork with 100 burns. The flow (F) has been studied by fluorophotometry using Yablonsky's protocol. Aqueous humor flow has been measured after 24 hours and after 7 days, to determine the immediate effects of laser trabeculoplasty; and also after 6 months for the long term effects. The initial aqueous humor flow was 1.35 microliters/min. By means of ANOVA we found statistically significant differences on aqueous humor flow after the 7th day (F = 1.67 microliters/min, p < 0.01), which remain six months later (F = 1.71 microliters/min, p < 0.01). This findings suggest that the effects of argon laser trabeculoplasty, either by mechanical or biological changes in the trabecular meshwork do not appear until the 7th day and remain throughout the follow up study.

Semiconductor Diode Laser Peripheral Iridotomy

To the Editor. —The ruby, argon, and neodymium-YAG lasers have each been used as an alternative to surgical iridectomy for the purpose of creating an opening in the iris. The semiconductor diode laser is a small, portable, light-weight laser that uses standard current and is air cooled. This instrument has been used in industry (eg, in telecommunications and compact disk players), and its potential ophthalmologic uses have only recently been examined. We report the use of a diode laser to perform a peripheral iridotomy. Report of a Case. —A 58-year-old brown-eyed man was referred for narrow angles. The patient denied any symptoms of angle closure glaucoma. Visual acuity was 20/25 -1 OD and 20/20 -1 OS. Intraocular pressures were 12 mm Hg OD and 13 mm Hg OS, and gonioscopy revealed only anterior trabecular meshwork bilaterally. The anterior chambers were 3 to 4 corneal thicknesses centrally and less than 1/8

Trabecular Repopulation by Anterior Trabecular Meshwork Cells After Laser Trabeculoplasty

To study further the transient increase in trabecular cell division within the first two days after laser trabeculoplasty in human corneoscleral explant organ cultures, we used a pulse-chase protocol in which immediately after laser treatment 3H-thymidine was added to the culture medium for 48 hours (the pulse period). Fresh medium without radiolabel was then added for variable times (the chase period) before termination of the experiment. Autoradiography was used to follow changes in the regional distribution of the cells that divided during the pulse period and had 3H-thymidine-labeled DNA. Laser-treated explants, evaluated after a pulse with no chase, showed a fourfold increase in cell division (P less than .001) over nontreated controls. Nearly 60% of this cell division was localized to the anterior, nonfiltering region of the trabecular meshwork where it inserts into the cornea beneath Schwalbe's line. Trabecular cell division in other regions of the meshwork was not increased over controls at this time. After seven or 14 days of chase without radiolabel, the regional distribution of radiolabeled cells changed in laser-treated explants but not in controls. By 14 days, only 26% of the labeled cells remained in this anterior insert region, while 60% were found in the region of the burn sites. Macroautoradiography of whole explants corroborated these observations. Our data support the hypothesis that laser trabeculoplasty causes early cell division by a population of cells in the anterior meshwork; these new cells then migrate and repopulate the burn sites over the next few weeks.

One Versus Two Simultaneous Goniotomies as the Initial Surgical Procedure for Primary Infantile Glaucoma

To evaluate whether a more extensive incision of the tissue adjacent to the anterior trabecular meshwork resulted in more effective control of intraocular pressure (IOP), seven infants with bilateral congenital glaucoma underwent a single goniotomy in one eye and two simultaneous goniotomies at separate sites in the second. Sodium hyaluronate (Healon) was used in all eyes undergoing two simultaneous goniotomies and in three to seven eyes undergoing a single goniotomy. Success was not significantly different, at 1 month or 1 year postoperatively, for eyes which underwent two simultaneous and separate goniotomies. Successful control of IOP was, however, related to the preoperative IOP. Eyes for which the initial procedure was unsuccessful had a significantly higher IOP. The incidence of postoperative hyphemas was less in eyes in which the Healon was used intraoperatively, but the use of Healon did not favorably or adversely affect intraocular pressure control.

The technic of argon laser trabeculoplasty and its results

Argon laser trabeculoplasty (ALT) was performed on 130 eyes with primary open-angle glaucoma or capsular glaucoma. Three different methods of ALT were employed to determine if the methods itself affects the incidence of immediate postoperative rises in intraocular pressure (IOP). Thirty-five eyes received 100 burns over 360 degrees of the posterior trabecular meshwork; these were categorized as Group 1. Group 2 comprised 77 eyes given 50 burns over 180 degrees of the posterior meshwork. Group 3 consisted of 18 eyes treated with 50 burns over 180 degrees of the anterior trabecular meshwork. The duration of each burn was 0.2 s in Group 1 and 0.1 s in Groups 2 and 3. The power of each burn ranged from 700 to 1000 mW in each group. Immediate postlaser IOP rise was defined as a pressure elevation exceeding prelaser value by 5 mmHg or more. In Group 1 the incidence of IOP rise was 82%; it was 58% after the first session in Group 2, but only 22% in Group 3. A sustained, marked pressure rise was most frequently observed in Group 1 as compared with the other two groups. Other complications, including sustained iritis, peripheral anterior synechiae and hyphema, were seen most frequently in Group 1 and least frequently in Group 3. Successful control of IOP, defined as an IOP of less than 20 mmHg, was achieved in 37% in Group 1, 70% in Group 2 and 56% in Group 3. The follow-up period ranged from 1.5 to 52 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraocular Pressure the Day of Argon Laser Trabeculoplasty in Primary Open-angle Glaucoma

Argon laser trabeculoplasty was performed in one eye of 57 phakic patients with primary open-angle glaucoma. The eyes received a mean of 78 ± 7 treatments over 360° to the anterior trabecular meshwork. The power was titrated to produce blanching without bubble formation. Increased intraocular pressure (range +1 to +22 mmHg) occurred in 30 of the 57 (53%) eyes 1 hour after treatment. Eight (14%) of these eyes had a clinically significant elevation defined by all of three criteria: (1) an intraocular pressure>30 mmHg, (2) greater than a 30% increase over the mean prelaser intraocular pressure, and (3) greater than a 10 mmHg increase over the peak prelaser diurnal intraocular pressure curve. These eight patients received either oral glycerine or acetazolamide. A rebound increase in intraocular pressure requiring repeat medical treatment occurred in four of the eight eyes. Two additional eyes without a pressure elevation 1 hour after treatment showed a later elevation. This was first detected 4 hours postoperatively in one eye and 7 hours after treatment in another eye. The 1-hour postoperative measurement detected most patients with clinically significant increased intraocular pressure (8 of 10 eyes) but these required continued observation for rebound increases. Patients with advanced glaucomatous visual field loss should also be followed closely to detect late increases in intraocular pressure (2 of 10 eyes).