Argon laser gonioplasty with trabeculoplasty for chronic angle-closure glaucoma

Gonioplasty with trabeculoplasty was used to treat 31 eyes of 25 patients (15 men and 10 women) with chronic angle-closure glaucoma. Ages ranged from 40 to 82 years (average, 60.4 yrs). The follow-up period was three to 36 months (average, 1 yr). During this time, 60% to 80% of eyes have maintained an intraocular pressure (IOP) less than 21 mm Hg and/or required less medication. The average IOP reduction was 7.9 mm Hg. Complications included focal, peaking, peripheral anterior synechiae in the lasered area in 19 of 31 eyes (61%), and permanently increased IOP in two of 31 eyes (6%). Gonioplasty was a useful method to differentiate between appositional angle closure and that due to peripheral anterior synechiae. After combined treatment, the chamber angle has remained open for more than a year in 60% to 80% of eyes.

Laser power and postoperative intraocular pressure increase in argon laser trabeculoplasty

Argon laser trabeculoplasty was performed on 45 open angle glaucoma patients with three different laser power levels (0.5, 0.7, and 0.9 W). We evaluated the influence of the treatment variables on the postoperative intraocular pressure (IOP) increase. The only statistically significant correlation we found was with the laser power. Most (75% [6/8]) of the serious IOP increases (greater than or equal to 10 mm Hg) were in the high-power group, and the average postoperative IOP increase was also greatest in this group.

Alterations of aqueous humour outflow following argon laser trabeculoplasty in monkeys

We performed argon laser trabeculoplasty in one eye in each of three cynomolgus monkeys, leaving the contralateral eyes as controls. Four weeks later in both eyes of each monkey we infused cationized ferritin as a tracer of the aqueous outflow pathways for 30-40 minutes before fixation. In the control eyes cationized ferritin was found throughout the conventional aqueous outflow tract, labelling trabecular endothelial cells, both inner and outer walls of Schlemm's canal, and the collecting channels. No permeation of cationized ferritin through continuous cellular layers such as the corneal endothelium was detected. In the lasered spots of the treated eyes cationized ferritin was found to label the cellular sheet covering the trabecular scar at the lasered site, but no tracer was detected within the scar or in Schlemm's canal immediately beneath. In contrast in adjacent non-lasered regions the trabecular cells, the observed juxta-canalicular herniations, and the vacuoles of the inner wall as well as Schlemm's canal itself were extensively labelled. Our findings suggest impermeability to aqueous humour flow through the actual lasered lesion, with shift of flow to adjacent, non-lasered regions. In the normal monkey these regions compensate structurally and functionally in ways that may help to deal with this diverted flow.

Ghost cell glaucoma in phakic eyes

We report 3 cases of ghost cell glaucoma all of which occurred in phakic patients with onset between 18 months and 4 years after vitreous haemorrhage. There appears to have been spontaneous disruption of the anterior hyaloid face in all 3 cases. Control of the glaucoma was achieved by medical treatment in one case and by trabeculectomy in two.

The prediction of intraocular pressure rise following argon laser trabeculoplasty

Forty-five patients with poorly controlled chronic open angle glaucoma underwent pneumotonography immediately prior to argon laser trabeculoplasty. The coefficient of facility of outflow (c-value) was calculated from the pneumotonography and correlated with the intraocular pressure rise one hour after the argon laser trabeculoplasty. It appeared that there was a strong relationship between a low c-value indicating a poor outflow facility and a large intraocular pressure rise following argon laser trabeculoplasty. The implications of being able to predict the intraocular pressure rise after argon laser trabeculoplasty are discussed.

Argon laser trabeculoplasty in narrow angle glaucoma

A prospective trial of argon laser trabeculoplasty (ALT) in narrow angle glaucoma (NAG) was undertaken. In eyes with NAG the mechanism of the glaucoma could be a combination of pupil block with subsequent irido-trabecular adhesion and trabecular damage with an increase in outflow resistance. To achieve relief of pupil block, eyes were randomly assigned to treatment with short pulsed laser iridotomy (LI) with the YAG or Dye lasers, or surgical peripheral iridectomy (PI). Alternatively, argon laser iridoplasty (IP) was performed to widen the anterior chamber angle sufficiently to permit ALT. Fifty-two eyes were treated and follow-up was from 12 to 22 months. A high rate of failure to control IOP with topical medication and progression of visual field loss occurred in all treatment groups. Iridoplasty followed by ALT was particularly unsuccessful as, in 50 per cent of cases, progressive synechial closure of the anterior chamber angle occurred following treatment. In eyes treated with PI/LI and ALT, the IOP control was improved in 12 per cent, unchanged in 30 per cent and remained uncontrolled in 58 per cent. By 15 months follow-up, a satisfactory outcome (IOP less than 21 mmHg on topical medication, visual field and acuity stable) was obtained in 24 per cent of the 33 eyes treated with PI/LI and ALT. Thirty-one of these eyes showed visual field loss. Of the 10 eyes that did not receive ALT following PI or LI, 90 per cent had a satisfactory outcome. Eight of these eyes showed little or no visual field loss. The authors conclude that iridoplasty followed by ALT is an unsuitable treatment for eyes with NAG. We further conclude that ALT is unlikely to be of benefit in eyes with NAG and visual field loss, even after pupil block has been relieved. Relief of pupil block alone may help eyes with early NAG without visual field loss.

Management of open-angle glaucoma

Open-angle glaucoma is a non-curable, blinding disease which has its best prognosis when management begins at its earliest onset. Recent studies, such as those demonstrating axonal loss before functional or physical changes occur, will have an effect on the current standard of management. This includes indications for initiating treatment as well as what constitutes controlled intraocular pressure. Pharmacological management is often difficult due to drug tolerance and compliance problems. Some types of secondary open angle glaucomas respond very poorly to treatment. Hence, an accurate diagnosis is imperative to proper management. Principles underlying pharmacological management are discussed. When pharmacological management fails, laser and/or surgical intervention is required to prevent further vision loss.

Limbus-based versus fornix-based conjunctival flaps in trabeculectomy

Forty consecutive trabeculectomies were performed by one surgeon, utilizing a limbus-based conjunctival flap in the first 20 eyes and a fornix-based flap in the remaining 20. A success rate of 90% was achieved in both groups, although eyes with limbus-based flaps had slightly better postoperative intraocular pressure control.

Retreatment with argon laser trabeculoplasty

Forty eyes in 37 patients that had previously successful 360 degrees argon laser trabeculoplasty were again found to have uncontrolled intraocular pressure (IOP) on maximally tolerated medical therapy and were retreated with argon laser trabeculoplasty to 180 degrees of the trabecular circumference. Successful retreatment was considered a decrease in IOP of 3 mmHg or more and sufficient to avoid further laser therapy or invasive glaucoma surgery. Laser trabeculoplasty retreatment was successful in 13 of the eyes treated (32%). Retreatment failed to control IOP in 27 of the retreated eyes (68%): either the IOP was not lowered by at least 3 mmHg (4 eyes) or the eyes required further laser therapy or surgery (23 eyes). The probability of successful IOP control 1 year after retreatment was 33% and only 14% after 1.75 years. No IOP elevations greater than 6 mmHg were recognized in the postlaser period. Although retreatment with argon laser trabeculoplasty can safely be used to control the IOP in some glaucomatous eyes, the likelihood of success is low.

Ciliary-block glaucoma treated by posterior capsulotomy

Ciliary-block glaucoma occurred in one eye of a 65-year-old-male, following a combined trabeculectomy and extracapsular lens extraction for long-standing angle-closure glaucoma. After pupillary block was excluded as a cause, a posterior capsulotomy resolved the condition. This procedure was repeated successfully when a flat anterior chamber recurred on spontaneous closure of the initial capsulotomy. The ciliary block appeared to be caused by the residual zonule and lens capsule.

[Argon laser trabeculoplasty in special forms of open-angle glaucoma]

Argon laser trabeculoplasty was performed in 71 eyes with complicated forms of open-angle glaucoma and insufficiently regulated intraocular pressure. The follow-up time was 18 +/- 6 months. The success rate was 35% in the group with secondary forms of glaucoma (37 treated eyes). Depending on the special indication a great difference in the subgroups was noted: the ALT failed in 4 cases of glaucoma after trauma, but was successful in 45% of all cases of aphakic glaucoma. Thirty-four eyes were treated by ALT after trabeculectomy had failed. The success rate in this group was 71%.

Glaucoma associated with penetrating keratoplasty

The occurrence of chronic postoperative glaucoma in 502 consecutive penetrating keratoplasty cases performed in 421 patients during 1978 through 1986 was 18% (91 cases). Immediate postoperative glaucoma occurred in 9% (44 cases) and progressive angle closure occurred in 2% (13 cases) of keratoplasties. Statistically significant risk factors for development of glaucoma were preexisting glaucoma and aphakia. The type of cataract extraction, use of an intraocular lens, or performance of vitrectomy did not pose significant risk of glaucoma. Surgical therapy of glaucoma was required in 24% of those with glaucoma and was most effective as cyclodestructive surgery especially in patients with progressive angle-closure glaucoma.

A common pathway for developmental glaucomas

In a clinicopathologic study of ten patients, utilizing a modified trabeculectomy technique for acquisition of histologic specimens, a high insertion of the iris was observed in four types of developmental glaucoma. A survey of the literature revealed additional developmental disorders with this abnormality of the anterior chamber angle. The common defect is believed to arise from a developmental arrest during the third trimester of gestation of tissues derived from cranial neural crest cells. The mechanism by which this developmental defect leads to aqueous outflow obstruction may, in some cases, be a paradoxical collapse of the trabecular meshwork and Schlemm's canal in response to contraction of the ciliary musculature, while other patients may have additional developmental abnormalities in the aqueous outflow system as the possible mechanism of glaucoma.