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PubMed1986

Vasoactive intestinal polypeptide-like immunoreactive nerves to the human eye.

Using immunohistochemical techniques, vasoactive intestinal polypeptide (VIP) is visualized in nerves distributed to the human eye. Immunoreactive nerve fibers occur about limbal blood vessels and within the trabecular meshwork. In the iris, free-running stromal nerves are the most common, but nerves to both dilator and sphincter muscles are present as well. Immunoreactive nerves are seen within the ciliary muscle and occasionally within a ciliary process. Innervation to choroidal blood vessels constitutes a prominent feature; innervation to more anterior uveal blood vessels is seen only irregularly. Immunoreactive to more anterior uveal blood vessels is seen only irregularly. Immunoreactive nerves are apposed to melanocytes throughout the uvea. The present findings extend prior reports in the human eye, indicating a potential role for VIP in ocular physiology. Additional neuroanatomical, biochemical and physiological studies are necessary to define fully the ocular function of VIP and to determine ultimely whether VIP has clinical and pharmacological implications.

Aqueous Humor↗
PubMed1989

Argon laser trabeculoplasty for chronic angle-closure glaucoma uncontrolled by iridotomy.

Nineteen eyes of 19 Japanese patients with medically uncontrollable chronic angle-closure glaucoma following laser iridotomy or surgical iridectomy underwent argon laser trabeculoplasty (ALT), applying low-power and a small number of laser burns over a small extent of the trabecular meshwork. All the eyes had glaucomatous optic disc damage, visual field loss, and intraocular pressure elevation before ALT. In each case, the extent of peripheral anterior synechiae was equal or less than 50% of the angle. The mean follow-up was 35 months. Life-table analysis (Kaplan-Meier method) showed that the probability of success was 66% at the end of three years after ALT. It is concluded that in the cases of uncontrollable chronic angle-closure glaucoma following laser iridotomy or surgical iridectomy, ALT should be tried before filtration surgery.

Female↗
PubMed1989

The immediate pressure response to primary laser trabeculoplasty--a comparison of one- and two-stage treatment.

The immediate pressure response to primary LTP was studied prospectively in 40 eyes randomised to one- and two-stage treatment in 360 degrees of the trabecular meshwork. There were 26 eyes with glaucoma capsulare and 14 with glaucoma simplex. Mean prelaser IOP was 32.8 mmHg in the former, and 35.5 mmHg in the latter group. The frequency and magnitude of postlaser pressure increase were the same in both groups when taking into consideration the pressure spikes in both 180 degrees sessions. The pressure increase was higher than in earlier reports on LTP in presurgical glaucoma patients on maximum medication. Almost all IOP elevations appeared during the first 2 h following laser treatment. The results were the same in both groups 6 months after LTP.

Aged↗
PubMed1990

Long-term efficacy of low power argon laser trabeculoplasty.

We studied the long-term efficacy of argon laser trabeculoplasty, applying low-power (a mean of 450 mW), a duration of 0.1 second, and a small number of burns (a mean total energy of 1.85 J) over 90 to 120 degrees of the trabecular meshwork. Fifty-four eyes with poorly controlled open-angle glaucoma were treated. The mean follow-up was 46 months. The mean intraocular pressure decrease was 5.3 mmHg in 35 eyes at one year, 6.1 mmHg in 23 eyes at 3 years, 5.1 mmHg in 13 eyes at 5 years, and 5.4 mmHg in 5 eyes at 6 years. Life-table analysis showed that the probability of success was 58% at one year, 49% at 3 years, and 46% at 5 years. Both the incidence and magnitude of the intraocular pressure rise in the early post-laser period were minimal and no serious complications were observed.

Aged↗
PubMed1990

Primary argon laser trabeculoplasty after pretreatment with timolol. A safe and economic therapy of early glaucoma.

In the treatment of glaucoma there are advantages and disadvantages associated with both medical, surgical and laser therapy. Early pressure rise has been found to be the main complication after laser treatment. In the present study primary argon laser trabeculoplasty (PALT) was carried out in 180 degrees of the trabecular meshwork with an effect of 0.4-0.6 W, after instillation of one drop of timolol 0.5%. Among our 27 newly diagnosed glaucoma patients no pressure rise or iritic reaction was detected. More than 50% of the patients were still managed with an intraocular pressure below 21 mmHg without medical or surgical treatment after 2 years. In addition to being virtually without side-effects this treatment modality is time saving and cost effective, and a great part of the patients may avoid medical therapy.

Aged↗
PubMed1993

Pseudoexfoliation syndrome: clinical factors related to capsular rupture in cataract surgery.

Extracapsular surgery has a high frequency of capsular rupture or disinsertion in patients with pseudoexfoliation syndrome. Irido-phakodonesis is one of the factors that suggests this complication. Irido-phakodonesis acts as an 'all or nothing' mechanism, as it does not appear until there is a certain degree of zonular lesion. We carried out a study on 330 eyes with pseudoexfoliation, relating irido-phakodonesis to 31 clinical signs. The results showed that irido-phakodonesis is related to cataracts, degree of mydriasis, presence of glaucoma, atrophy of the pupilar pigmentary ruff, and uniform pigmentation of the trabecular meshwork. These results suggest that the signs which indicate the existence of zonular lesion during extracapsular surgery, include poor dilation, the presence of glaucoma and pigmentary alterations, whilst the pseudoexfoliation material deposited in the anterior segment does not appear to have a bearing on this complication.

Aged↗
PubMed1994

Transconjunctival sinusotomy using the 193-nm excimer laser.

Successful surgical management of glaucoma is limited as a consequence of undesired fibroblastic response of episcleral tissues. In 10 rabbit and three human eye bank eyes, we have performed a modified sinusotomy procedure using the 193-nm excimer laser. The technique is minimally invasive. Conjunctiva is pulled over the corneoscleral limbus, and a slit-shaped (1 x 2 mm) excimer beam ablates through conjunctiva and external sclera until penetrating the outer wall of Schlemm's canal, at which time brisk egress of fluid is noted. The conjunctiva is allowed to retract, and a conjunctival bleb is formed. A single suture is used to close the conjunctival defect. Intraocular pressure in the rabbit eye was decreased from 10.0 +/- 1.8 to 4.9 +/- 1.8 mmHg immediately after surgery (p < 0.0001). Histology revealed a partial thickness, smooth-walled ablation consistent with a sinusotomy. This procedure is minimally invasive and may be useful for management of glaucoma, particularly when a substantial component of the impediment to aqueous outflow is external to the trabecular meshwork.

Animals↗
PubMed1983

Potentiation of glucocorticoid activity by 5 beta-dihydrocortisol: its role in glaucoma.

5 beta-Dihydrocortisol potentiated the threshold level (the smallest dose producing a measurable effect) of topically applied cortisol (0.02 percent) and dexamethasone (0.003 percent) in causing nuclear translocation of the cytosolic glucocorticoid receptor in rabbit iris-ciliary body tissue. 5 beta-Dihydrocortisol accumulates in cells cultured from trabecular meshwork specimens from patients with primary open-angle glaucoma, but not in similar cells derived from nonglaucomatous patients. In view of the sensitivity of patients with primary open-angle glaucoma to the effects of glucocorticoids in raising intraocular pressure, this potentiation may be responsible for the steroid sensitivity and for the ocular hypertension seen in this disorder.

Animals↗
PubMed2001

Targeted Disruption of the Myocilin Gene (Myoc) Suggests that Human Glaucoma-Causing Mutations Are Gain of Function.

Glaucoma is a heterogeneous eye disease and a major cause of blindness worldwide. Recently, primary open angle glaucoma (POAG)-associated mutations have been found in the trabecular meshwork inducible glucocorticoid response gene (TIGR), also known as the myocilin gene (MYOC), at the GLC1A locus on chromosome 1q21-q31. These mutations occurred in a subset of patients with juvenile- and adult-onset POAG and exhibited autosomal dominant inheritance. Ocular expression and its involvement in POAG suggest that TIGR/MYOC may have a role(s) in regulating intraocular pressure (IOP). Here, we report the generation and analysis of mice heterozygous and homozygous for a targeted null mutation in Myoc. Our study shows that Myoc mutant mice are both viable and fertile. Our in vivo findings further demonstrate that Myoc is not required for normal IOP or normal ocular morphology. The lack of a discernable phenotype in both Myoc-heterozygous and Myoc-null mice suggests that haploinsufficiency is not a critical mechanism for POAG in individuals with mutations in MYOC. Instead, disease-causing mutations in humans likely act by gain of function.

Animals↗
PubMed2004

Defining "occludable" angles in population surveys: drainage angle width, peripheral anterior synechiae, and glaucomatous optic neuropathy in east Asian people.

BACKGROUND: /aim: A current consensus in epidemiological studies of primary angle closure (PAC) is to diagnose the condition only if the posterior (usually pigmented) trabecular meshwork is seen for less than 90 degrees of the angle circumference, termed an "occludable angle." The authors sought to assess the validity of this epidemiological classification by exploring the relation between drainage angle width, peripheral anterior synechiae (PAS) and glaucomatous optic neuropathy (GON). METHODS: 918 Mongolians and 995 Chinese Singaporeans, both groups aged 40 years and older were examined in two population based surveys. Gonioscopic angle width was graded in five categories (0 = closed to 4 = wide open) according the scheme described by Shaffer. Cases with secondary PAS were excluded. RESULTS: The rate of PAS was between 0.3% and 1.7% in people with wide angles (grades 3 and 4). In those with grade 2 angles, PAS were seen in between 8% of eyes. In eyes with grade 1 angles, the rate rose to 17% in Chinese Singaporeans, and 31% in Mongolians. The odds of PAS were higher in people with narrower angles. However, there was a greater absolute number of people with PAS whose drainage angles were classified as "not occludable" than those classified "occludable." CONCLUSIONS: The traditional view that primary angle closure becomes a significant possibility in drainage angles of < or = grade 2 (approximately 20 degrees ) is valid in east Asians. The definition of an "occludable" angle examined here excludes many people with PAS. This probably serves to underemphasise the role of PAC in population surveys of glaucoma prevalence in Asian people.

Adult↗
PubMed2006

Selective laser trabeculoplasty versus argon laser trabeculoplasty: results from a 1-year randomised clinical trial.

AIMS: To compare selective laser trabeculoplasty (SLT) and argon laser trabeculoplasty (ALT), in terms of intraocular pressure (IOP) lowering, in patients with open-angle glaucoma. METHODS: 176 eyes of 152 patients were enrolled in this study, 89 in the SLT and 87 in the ALT groups. Patients were randomised to receive either SLT or ALT treatment to 180 degrees of the trabecular meshwork. Patients were followed up to 12 months after treatment. The main outcome measured was IOP lowering at 12 months after treatment, compared between the SLT and ALT groups. RESULTS: No significant difference (p = 0.846) was found in mean decrease in IOP between the SLT (5.86 mm Hg) and ALT (6.04 mm Hg) groups at 1 year or at any other time points, nor were there any significant differences in the rate of early or late complications between the two groups. CONCLUSIONS: SLT is equivalent to ALT in terms of IOP lowering at 1 year, and is a safe and effective procedure for patients with open-angle glaucoma.

Aged↗
PubMed1976

The syndrome of closed-angle glaucoma.

Closed-angle glaucoma is the result of two mechanisms acting either separately or in combination: 1. Pupil block creates a greater pressure in the posterior than in the anterior chamber, pushing the iris on to the cornea. 2. Increased trabecular meshwork outflow in the presence of pupil block creates a lower pressure in the anterior chamber than in the posterior, pulling the iris on to the cornea. Three main groups of eyes manifest closed-angle glaucoma: (i) Mechanism (I) is necessary and sufficient, but (2) precludes the development of angle closure. (ii) Mechanism (I) is necessary but insufficient. Mechanism (2) must also be present. (iii) Mechanism (I) is necessary and sufficient but (I) and (2) may combine to produce an acute attack.

Amides↗
PubMed1979

One gonioscopic fallacy.

Traditional gonioscopic practice assumes that, if most of the angle is gonioscopically closed, intraocular pressure increases. Evidence is produced to show that this is fallacious, because at its inception angle closure is iridocorneal contact occurring on the corneal side of the limbus. Although the angle cannot be seen by means of a gonioscope, there is initially no iridotrabecular contact. It is only after pressure increases that iris is pushed against trabecular meshwork and the angle is truly closed.

Aged↗
PubMed1980

Iridocycloretraction in closed-angle glaucoma.

A small series of patients who underwent iridocycloretraction between 1969 and 1976 is analysed. All patients had previously undergone peripheral iridectomy for primary angle-closure glaucoma, and all had 360 degrees of peripheral anterior synechiae, as seen with the gonioscope. It was found that iridocycloretraction was successful in an unacceptably low percentage of cases, and its success was related to whether subconjunctival drainage was established. There was no clinical evidence to support the theory that its main mode of action was to permit access of aqueous to the trabecular meshwork. Therefore it has no practical advantages over other procedures which establish subconjunctival filtration.

Adult↗
PubMed1986

Subconjunctival suspension of RU486 lowers intraocular pressure in normal rabbits.

RU486 is both a progesterone blocker and a corticosteroid blocker (peripheral). Subconjunctival injections of 0.2 ml of a 1% suspension of RU486 powder (2 mg) were given twice weekly to one eye chosen at random of 12 rabbits. The fellow eye received the same volume, 0.2 ml, of vehicle (normal saline) only. Ocular tension was measured twice daily for six days per week by an Alcon pneumatonograph, the tonometrist(s) being unaware of which eyes were treated and which untreated. A small but significant reduction in intraocular pressure, about 0.7 mmHg, occurred in treated eyes. No intereye difference in the ocular hypertensive response to intraperitoneal injections of distilled water (50 ml/kg) was found. Clinical trials are planned in which a larger fall is expected because the trabecular meshwork in patients with open-angle glaucoma or ocular hypertension is presumably more affected by (normal) tissue levels of corticosteroid.

Animals↗
PubMed1992

Modification of trabeculectomy to avoid postoperative hyphaema. The 'guarded anterior fistula' operation.

The effect of varying the position of a trabeculectomy fistula on the rate of postoperative hyphaema was studied in a prospective randomised trial. One eye of each of 78 consecutive patients with primary open angle glaucoma and exfoliation glaucoma was allocated to one of two groups. In group A the fistula was fashioned anterior to the scleral spur, entirely in corneal tissue. In group B the fistula included cornea and sclera with trabecular meshwork and scleral spur. Seven out of 39 eyes (18%) in group A developed a postoperative hyphaema with detectable blood level, compared with 22 out of 39 eyes (56%) for group B (p less than 0.001). In addition, the severity of the bleeding was greater in group B, and the three cases of recurrent bleeding were all in this group. Group B patients remained in hospital for an average of 3.9 days, which was significantly longer (p = 0.004) than the average of 2.9 days for group A. This difference was related to the frequency and severity of the hyphaema. The type of dissection or the occurrence of hyphaema did not influence the intraocular pressure at 4 months after surgery.

Aged↗
PubMed1998

Prevalence and management of elevated intraocular pressure in patients with Graves' orbitopathy.

AIMS: To investigate the prevalence and to discuss the necessity of treating elevated intraocular pressures (IOP) in patients with Graves' orbitopathy (GO). In addition, to study the effects of orbital decompression and extraocular muscle surgery on IOP. METHODS: The records of consecutive patients with GO referred in a 5 year period were studied and those selected, in which glaucoma medication had been prescribed, or a diagnosis of primary open angle glaucoma (POAG) or of ocular hypertension (> or = 22 mm Hg) (OH) had been made. The necessity of treating these patients with glaucoma medication was questioned and the effects of corticosteroids, orbital decompression, and extraocular muscle surgery on the IOP were evaluated. RESULTS: Of 482 patients with GO, 23 (4.8%) met the inclusion criteria. Four patients (0.8%) had POAG, four had elevated IOPs and visual field defects consistent with dysthyroid optic neuropathy, and 15 (3.1%) had only elevated IOPs. Five patients with OH showed a permanent drop of IOP after orbital decompression, two had a marked decrease of their IOP after recession of the inferior rectus muscle. CONCLUSIONS: POAG has the same prevalence in the general Dutch population as in the GO subgroup. The combination of elevated IOPs and visual field defects in GO patients may be attributed to other mechanisms than obstructed aqueous outflow in the trabecular meshwork and should be treated accordingly. Orbital decompression and extraocular muscle surgery may lower the IOP in patients with GO.

Adult↗
PubMed1999

Localised retinal nerve fibre layer defects in chronic experimental high pressure glaucoma in rhesus monkeys.

AIM: To evaluate prospectively in an experimental model of chronic high pressure glaucoma whether the concept of a mainly diffuse pattern of optic nerve damage holds true for high pressure glaucoma. METHODS: The study comprised nine eyes of nine rhesus monkeys (Macaca mulatta) with a mean age of 17.7 (SD 3.1) years (range 13-23 years). Experimental glaucoma was produced by multiple applications of argon laser to the trabecular meshwork. Applanation tonometry was regularly performed and fundus photographs, which were taken serially, were used for retinal nerve fibre layer (RNFL) assessment and morphometric optic disc analysis. Six monkeys, in which arterial hypertension and atherosclerosis had additionally been induced several years before elevation of intraocular pressure, did not show any sign of diffuse loss or localised defects of the RNFL before initiation of glaucoma. RESULTS: Compared with the same eyes at baseline, localised RNFL defects had developed in eight (89%) eyes. It included all three eyes (100%) of the monkeys without arterial hypertension/arteriosclerosis, and five of the six monkeys (83%) with arterial hypertension/arteriosclerosis. Four eyes had multiple localised RNFL defects. In all eyes, diffuse RNFL loss was additionally present. CONCLUSIONS: Besides diffuse loss of RNFL, localised RNFL defects were present in almost all eyes of monkeys with chronic experimental high pressure glaucoma. Challenging the concept that a mostly diffuse type of optic neuropathy occurs in high pressure glaucoma, the results suggest that, in high pressure glaucoma, at least a mixture of localised and diffuse pattern of optic nerve damage prevails.

Animals↗