Vascular tone pathway polymorphisms in relation to primary open-angle glaucoma.

AIMS: Vascular perfusion may be impaired in primary open-angle glaucoma (POAG); thus, we evaluated a panel of markers in vascular tone-regulating genes in relation to POAG. METHODS: We used Illumina 660W-Quad array genotype data and pooled P-values from 3108 POAG cases and 3430 controls from the combined National Eye Institute Glaucoma Human Genetics Collaboration consortium and Glaucoma Genes and Environment studies. Using information from previous literature and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, we compiled single-nucleotide polymorphisms (SNPs) in 186 vascular tone-regulating genes. We used the 'Pathway Analysis by Randomization Incorporating Structure' analysis software, which performed 1000 permutations to compare the overall pathway and selected genes with comparable randomly generated pathways and genes in their association with POAG. RESULTS: The vascular tone pathway was not associated with POAG overall or POAG subtypes, defined by the type of visual field loss (early paracentral loss (n=224 cases) or only peripheral loss (n=993 cases)) (permuted P≥0.20). In gene-based analyses, eight were associated with POAG overall at permuted P<0.001: PRKAA1, CAV1, ITPR3, EDNRB, GNB2, DNM2, HFE, and MYL9. Notably, six of these eight (the first six listed) code for factors involved in the endothelial nitric oxide synthase activity, and three of these six (CAV1, ITPR3, and EDNRB) were also associated with early paracentral loss at P<0.001, whereas none of the six genes reached P<0.001 for peripheral loss only. DISCUSSION: Although the assembled vascular tone SNP set was not associated with POAG, genes that code for local factors involved in setting vascular tone were associated with POAG.

Nitric oxide attenuates alpha(2)-adrenergic receptors by ADP-ribosylation of G(i)alpha in ciliary epithelium.

PURPOSE: To determine the mechanism by which nitric oxide (NO) regulates alpha(2)-adrenergic receptor coupling to adenylyl cyclase in bovine ciliary epithelium. METHODS: Ciliary epithelial explants were dissected, cultured, and labeled with [(3)H]adenine. [(3)H]Adenosine 3',5'-cyclic monophosphate (cAMP) was measured under basal conditions and after exposure to forskolin, isoproterenol, clonidine, yohimbine, pertussis toxin, and the NO donor spermine-NO. Endogenous and NO-stimulated ADP-ribosylation of ciliary epithelial membrane proteins was determined by [(32)P]nicotinamide adenosine diphosphate (NAD) labeling and autoradiography. The three isoforms of the G(i)alpha protein subunit were evaluated by Western blot analysis. RESULTS: Basal [(3)H]cAMP content was 13.4 +/- 1.3 picomoles/mg protein (SEM). Both isoproterenol and forskolin stimulated [(3)H]cAMP accumulation to 36.0 +/- 3.9 and 73.2 +/- 17.5 picomoles/mg protein, respectively. Clonidine did not affect basal [(3)H]cAMP levels, but attenuated both isoproterenol- and forskolin-mediated [(3)H]cAMP accumulation to 23.2 +/- 4.4 and 31.6 +/- 4.6 picomoles/mg protein, respectively. Yohimbine antagonized the clonidine-mediated adenylyl cyclase inhibition. Pertussis toxin blocked the effect of clonidine. In the presence of the NO donor spermine-NO, the clonidine-mediated inhibition of forskolin- and isoproterenol-stimulated cAMP accumulation was attenuated completely. NO significantly stimulated endogenous [(32)P]ADP-ribosylation of a 40-kDa membrane protein. Western blot analysis with specific antibodies revealed expression of all three G(i) subtypes--G(i1)alpha, G(i2)alpha, and G(i3)alpha--in bovine ciliary epithelium. CONCLUSIONS: NO attenuates alpha(2)-adrenergic receptor-mediated inhibition of adenylyl cyclase in ciliary epithelium through ADP-ribosylation of the G(i)alpha subunit. The findings demonstrate heterologous regulation between the NO and cAMP signaling pathways in ciliary epithelium.

Age-dependent prevalence of mutations at the GLC1A locus in primary open-angle glaucoma.

PURPOSE: To screen a population with primary open-angle glaucoma for mutations in the gene that encodes the trabecular meshwork inducible glucocorticoid response protein (TIGR), also known as myocilin (MYOC). METHODS: Ophthalmologic information was collected for study subjects with primary open-angle glaucoma and their relatives. Mutation screening of 74 primary open-angle glaucoma probands was conducted by sequencing TIGR/MYOC coding sequence and splice sites. RESULTS: In 23 families we detected 13 nonsynonymous sequence changes, nine of which appear to be mutations likely to cause or contribute to primary open-angle glaucoma. Two mutations, Arg272Gly and Ile499Ser, and one nonsynonymous sequence variant, Asn57Asp, are novel. We found mutations in nine of 25 juvenile glaucoma probands (36%) and two of 49 adult-onset glaucoma probands (4%). Age classification of families rather than individual probands revealed mutations in three of nine families with strictly juvenile primary open-angle glaucoma (33%), and no mutations in 39 families with strictly adult-onset primary open-angle glaucoma (0%). In families with mixed-onset primary open-angle glaucoma containing both juvenile primary open-angle glaucoma and adult-onset primary open-angle glaucoma cases, we found mutations in eight of 26 families (31%). CONCLUSIONS: Our data suggest that Gly252Arg, Arg272Gly, Glu323Lys, Gln368STOP, Pro370Leu, Thr377Met, Val426Phe, Ile477Asn, and Ile499Ser are likely to play roles that cause or contribute to the etiology of autosomal dominant primary open-angle glaucoma. Our finding of more TIGR/MYOC mutations in families with mixed-onset primary open-angle glaucoma than in the families with strictly adult-onset primary open-angle glaucoma implies that the presence of relatives with juvenile primary open-angle glaucoma in a family could be used as a basis for identifying a subset of the population with adult-onset primary open-angle glaucoma with higher prevalence of TIGR/MYOC mutations. To address this issue, and to refine estimations of mutation prevalence in these age-defined subpopulations, prospective study of a larger population ascertained entirely through adult-onset primary open-angle glaucoma probands will be needed.

Visual field results after vitreous surgery in a case series of patients with open-angle glaucoma.

BACKGROUND AND OBJECTIVE: Visual field loss is a complication of vitrectomy and a concern for patients with glaucoma. Our objective was to determine whether vitrectomy is associated with new field defects in patients with glaucoma. PATIENTS AND METHODS: This retrospective case series involved 7 eyes of 7 patients, who had open-angle glaucoma and underwent vitrectomy for macular hole (2) or epiretinal membrane (5). RESULTS: Acuity improved by at least two lines in 5 eyes. Visual fields showed a change in mean deviation following vitrectomy (mean difference -1.50 dB, P=0.0006, paired Student's t-test). One eye had confirmed progression of a pre-existing visual field defect, but no new defects were apparent in the other eyes. Transient intraocular pressure rises requiring therapy occurred in 3 eyes. One eye developed macular edema, but no other operative complications occurred. CONCLUSIONS: The results of our small case series suggest that vitrectomy may be an acceptable intervention in eyes with glaucoma and co-existing macular problems.

Phacoemulsification and intraocular lens placement in eyes with cataract and congenital coloboma: visual acuity and complications.

PURPOSE: To evaluate the safety and complications of phacoemulsification in a series of patients with congenital coloboma and cataract. SETTING: University-based hospital practice. METHODS: A retrospective review was conducted of consecutive patients who had coloboma and cataract and had phacoemulsification between January 1987 through December 1998. Complications and visual acuity 2 months postoperatively were assessed. RESULTS: Mean age of 7 cases at the time of surgery was 41.6 years +/- 11.1 (SD). Visual acuity improved in 6 of 7 eyes; 1 eye had no change. Six eyes had no serious complications. In 1 eye, a retinal detachment was observed postoperatively, but there was no loss in visual acuity. Another patient developed postoperative monocular diplopia from exposure of the intraocular lens (IOL) edge within the inferonasally located corectopia associated with the coloboma. Nonsurgical treatment was unsuccessful, but this symptom resolved after surgical pupilloplasty. CONCLUSIONS: The results of this small case series affirm that clinically significant cataract develops at a younger age in eyes with congenital coloboma than in eyes with typical age-related nuclear sclerotic cataract. Monocular diplopia, a potential complication after cataract surgery in these eyes, can be managed by pupilloplasty. The improved vision in this study indicates that phacoemulsification and IOL placement are safe and beneficial in patients with typical congenital coloboma and cataract.

Cell signaling in bovine ciliary epithelial organ culture.

The ciliary epithelium secretes aqueous humor, an intraocular fluid whose production is regulated in part by transmembrane signaling pathways including those mediated by G protein-coupled receptors. Many drugs, such as beta-adrenergic receptor (AR) antagonists and alpha2-AR agonists, are used to lower intraocular pressure by presumably decreasing fluid transport across this epithelium. Hence, our purpose was to establish a ciliary epithelial organ culture system suitable for the study of cell signaling pathways. A trypsin-mediated dissection method was established to isolate bovine ciliary epithelial sheets. These sheets were cultured in a 5% CO2 incubator. The quality was assessed by light microscopy, by protein analysis, and by the evaluation of epinephrine-mediated phosphoinositide turnover. The cultured epithelial explants were viable as evidenced by minimal trypan blue staining. The explants were composed primarily of nonpigmented cells and some pigmented cells, but no other ciliary body tissues were present on histology. Membrane preparations showed proteins with a distribution from 31 to 116 kDa. Epinephrine caused a dose-dependent increase in [3H]inositol phosphates (InsPs) accumulation with a maximal increase of two- to three-fold over basal levels. This epinephrine-mediated increase was inhibited by prazosin. We established an organ culture system of isolated bovine ciliary epithelium suitable for the study of transmembrane signaling pathways.

Autosomal dominant hemorrhagic macular dystrophy not associated with the TIMP3 gene.

OBJECTIVE: To describe the ophthalmic and genetic findings of a large kindred (UM:H389) with autosomal dominant hemorrhagic macular dystrophy. METHODS: The disease state of family members was documented by dilated fundus examination, electroretinography, color vision tests, fluorescein angiography, measurement of visual fields, biomicroscopy, gonioscopy, and intraocular pressure measurement. Linkage and haplo-type analyses were carried out with markers flanking the Sorsby fundus dystrophy TIMP3 (tissue inhibitor of metalloproteinase 3) gene locus, and mutation analysis was carried out by screening exon 5 of the TIMP3 gene. RESULTS: This 4-generation pedigree with autosomal dominant hemorrhagic macular degeneration has visual symptoms beginning in the sixth decade of life. Several family members developed choroidal neovascular membrane formation in the macula of both eyes. The phenotype overlaps that of Sorsby fundus dystrophy. Some of the affected members have unusual zonularlike radial striations on the anterior lens capsule surface, and glaucoma or ocular hypertension has developed in 2 of them. Involvement of the TIMP3 gene was excluded by linkage, haplotype, and mutation analyses. CONCLUSIONS: The phenotype of this family with autosomal dominant macular dystrophy overlaps that of Sorsby fundus dystrophy. Exclusion of the TIMP3 gene in this family indicates genetic heterogeneity for hemorrhagic macular dystrophy. Anterior segment anomalies may occur with this condition, but cosegregation has not yet been established. CLINICAL RELEVANCE: This study broadens the spectrum of hemorrhagic macular dystrophy by identifying a family in which the TIMP3 gene is not involved. Once the gene is cloned, we are eager to learn whether this gene may be involved in age-related macular degeneration.

Cystoid macular edema associated with latanoprost therapy in a case series of patients with glaucoma and ocular hypertension.

OBJECTIVE: To identify coexisting ocular diagnoses in a case series of eyes that developed cystoid macular edema (CME) associated with latanoprost therapy. DESIGN: Retrospective observational case series. PARTICIPANTS: Seven eyes of seven patients who developed CME possibly associated with latanoprost treatment were studied. INTERVENTION: When these patients, all of whom were treated with latanoprost in addition to other glaucoma medications, described blurred vision or eye irritation, ocular examination revealed CME, which was confirmed by fluorescein angiography. Latanoprost was discontinued, and in three cases topical corticosteroids and nonsteroidal anti-inflammatory agents were used to treat the CME. MAIN OUTCOME MEASURES: Visual acuity and intraocular pressure were determined before latanoprost use began, during therapy, and after latanoprost use ceased. In these cases, resolution of CME was documented clinically after discontinuing latanoprost. RESULTS: Clinically significant CME developed after 1 to 11 months of latanoprost treatment, with an average decrease of 3 lines in Snellen visual acuity. Intraocular pressure decreased an average of 27.9% during treatment. Cystoid macular edema was confirmed in all cases by fluorescein angiography. In these seven patients, the following coexisting ocular conditions may have placed these eyes at risk for prostaglandin-mediated blood-retinal barrier vascular insufficiency: history of dipivefrin-associated CME, epiretinal membrane, complicated cataract surgery, history of macular edema associated with branch retinal vein occlusion, history of anterior uveitis, and diabetes mellitus. In all cases, the macular edema resolved following discontinuation of latanoprost, in some instances with concomitant use of steroidal and nonsteroidal anti-inflammatory agents. CONCLUSIONS: In this case series of pseudophakic, aphakic, or phakic eyes, the temporal relationships between the use of latanoprost and developing CME, and the resolution of CME following cessation of the drug, suggest an association between latanoprost and CME. In all cases, coexisting ocular conditions associated with an altered blood-retinal barrier were present.