Predictive factors for glaucomatous visual field progression in the Advanced Glaucoma Intervention Study

PURPOSE

To investigate the risk factors associated with visual field (VF) progression in the Advanced Glaucoma Intervention Study (AGIS) with pointwise linear regression (PLR) analysis of serial VFs.

DESIGN

Prospective, multicenter, randomized clinical trial.

PARTICIPANTS

Five hundred nine eyes of 401 patients from the AGIS with a baseline VF score of <or=16, >or=7 VF examinations, and >or=3 years of follow-up were selected.

MAIN OUTCOME MEASURE

Visual field progression.

METHODS

This is a cohort study of patients enrolled in a prospective randomized clinical trial (AGIS). Worsening of a test location on PLR analysis was defined as a change of threshold sensitivity of >or=1.00 decibels a year, with P<or=0.01. Visual field progression was defined as worsening of at least 2 test locations within a Glaucoma Hemifield Test cluster with PLR analysis. Multivariate logistic regression was used to determine risk factors associated with VF worsening. Intraocular pressure (IOP) fluctuation was defined as standard deviation of the IOP at all visits after the initial surgery.

RESULTS

The mean (+/- standard deviation) follow-up time and baseline AGIS score were 7.4 (+/-1.7) years and 7.7 (+/-4.4), respectively. Visual field progression was detected with PLR analysis in 151 eyes (30%). Older age at the initial intervention (P = 0.0012; odds ratio [OR], 1.30; 95% confidence interval [CI], 1.11-1.50), larger IOP fluctuation (P = 0.0013; OR, 1.31; 95% CI, 1.12-1.54), increasing number of glaucoma interventions (P = 0.01; OR, 1.74; 95% CI, 1.14-2.64), and longer follow-up (P = 0.02; OR, 1.19; 95% CI, 1.03-1.38) were associated with increased odds of VF progression. When regression analyses were repeated in eyes with and without a history of cataract extraction, IOP fluctuation was the only variable to be consistently associated with VF progression.

CONCLUSION

Both increasing age and greater IOP fluctuation increase the odds of VF progression by 30% (for each 5-year increment in age and 1-mmHg increase in IOP fluctuation). The higher risk conferred by IOP fluctuation was consistently observed in eyes with and without a history of cataract extraction.

Common variants at 9p21 and 8q22 are associated with increased susceptibility to optic nerve degeneration in glaucoma

Optic nerve degeneration caused by glaucoma is a leading cause of blindness worldwide. Patients affected by the normal-pressure form of glaucoma are more likely to harbor risk alleles for glaucoma-related optic nerve disease. We have performed a meta-analysis of two independent genome-wide association studies for primary open angle glaucoma (POAG) followed by a normal-pressure glaucoma (NPG, defined by intraocular pressure (IOP) less than 22 mmHg) subgroup analysis. The single-nucleotide polymorphisms that showed the most significant associations were tested for association with a second form of glaucoma, exfoliation-syndrome glaucoma. The overall meta-analysis of the GLAUGEN and NEIGHBOR dataset results (3,146 cases and 3,487 controls) identified significant associations between two loci and POAG: the CDKN2BAS region on 9p21 (rs2157719 [G], OR = 0.69 [95%CI 0.63-0.75], p = 1.86×10⁻¹⁸), and the SIX1/SIX6 region on chromosome 14q23 (rs10483727 [A], OR = 1.32 [95%CI 1.21-1.43], p = 3.87×10⁻¹¹). In sub-group analysis two loci were significantly associated with NPG: 9p21 containing the CDKN2BAS gene (rs2157719 [G], OR = 0.58 [95% CI 0.50-0.67], p = 1.17×10⁻¹²) and a probable regulatory region on 8q22 (rs284489 [G], OR = 0.62 [95% CI 0.53-0.72], p = 8.88×10⁻¹⁰). Both NPG loci were also nominally associated with a second type of glaucoma, exfoliation syndrome glaucoma (rs2157719 [G], OR = 0.59 [95% CI 0.41-0.87], p = 0.004 and rs284489 [G], OR = 0.76 [95% CI 0.54-1.06], p = 0.021), suggesting that these loci might contribute more generally to optic nerve degeneration in glaucoma. Because both loci influence transforming growth factor beta (TGF-beta) signaling, we performed a genomic pathway analysis that showed an association between the TGF-beta pathway and NPG (permuted p = 0.009). These results suggest that neuro-protective therapies targeting TGF-beta signaling could be effective for multiple forms of glaucoma.

Genome-wide association analysis identifies TXNRD2, ATXN2 and FOXC1 as susceptibility loci for primary open-angle glaucoma

Primary open angle glaucoma (POAG) is a leading cause of blindness world-wide. To identify new susceptibility loci, we meta-analyzed GWAS results from 8 independent studies from the United States (3,853 cases and 33,480 controls) and investigated the most significant SNPs in two Australian studies (1,252 cases and 2,592 controls), 3 European studies (875 cases and 4,107 controls) and a Singaporean Chinese study (1,037 cases and 2,543 controls). A meta-analysis of top SNPs identified three novel loci: rs35934224[T] within TXNRD2 (odds ratio (OR) = 0.78, P = 4.05×10⁻¹¹ encoding a mitochondrial protein required for redox homeostasis; rs7137828[T] within ATXN2 (OR = 1.17, P = 8.73×10⁻¹⁰), and rs2745572[A] upstream of FOXC1 (OR = 1.17, P = 1.76×10⁻¹⁰). Using RT-PCR and immunohistochemistry, we show TXNRD2 and ATXN2 expression in retinal ganglion cells and the optic nerve head. These results identify new pathways underlying POAG susceptibility and suggest novel targets for preventative therapies.

Long-term outcome of initial ciliary ablation with contact diode laser transscleral cyclophotocoagulation for severe glaucoma. The Diode Laser Ciliary Ablation Study Group

PURPOSE

To learn the long-term outcome of ciliary ablation with diode laser contact transscleral cyclophotocoagulation (TSCPC) in eyes with recalcitrant, severe glaucoma.

METHODS

Twenty-seven eyes of 27 patients with medically and surgically uncontrollable glaucoma and no previous ciliary ablation enrolled in this study. After baseline measurements and informed consent, the authors performed contact TSCPC. There were 14 pseudophakic, 7 aphakic, and 6 phakic eyes; 15 of these had primary open angle glaucoma and the remainder had various secondary or open- or closed-angle glaucomas. Median follow-up was 19 months (range, 6 weeks to 27 months). Initially after laser surgery, glaucoma medications were continued, except for a 2-week interruption of miotics; the ophthalmologist later adjusted medications in accordance with the patient's status. The authors define failure of TSCPC in two ways, based on IOP measurements during two consecutive study examinations 6 weeks or more after intervention or at the final examination: (1) less than 20% intraocular pressure (IOP) reduction from baseline, and (2) either less than 20% reduction of IOP from baseline or IOP greater than 22 mmHg.

RESULTS

For 27 eyes, the baseline IOP (mean +/- standard deviation) was 36.4 +/- 12.4 mmHg (range, 20-70 mmHg). The mean IOP at last examination was 20.3 +/- 8.7 mmHg. With failure definition 1, the cumulative probability of success was 84% at 1 year and 62% at 2 years. With failure definition 2 the cumulative probability of success was 72% at 1 year and 52% at 2 years. At the last examination, 19 eyes (70%) had visual acuity improved within one line of visual acuity at eligibility. One of these eyes, with light perception vision at entry, declined to no light perception. Three eyes (11%) lost two lines of vision and five (19%) lost three or more lines.

CONCLUSIONS

Contact diode laser TSCPC yields long-term improvement of IOP and preservation of visual acuity in a substantial proportion of eyes with severe, medically uncontrolled glaucoma.

The Advanced Glaucoma Intervention Study (AGIS): 1. Study design and methods and baseline characteristics of study patients

Medical therapy has been the standard initial treatment for open-angle glaucoma. When some visual field has been lost and maximum tolerated and effective medical therapy does not succeed in controlling the disease, the patient is considered to have advanced glaucoma, and the first of a potential sequence of surgical treatments is usually indicated. Little is known about the long-term course and prognosis of advanced glaucoma or about the long-term effectiveness of sequential surgical treatments in controlling the disease and preventing vision loss and blindness. The Advanced Glaucoma Intervention Study was designed to study, in advanced glaucoma, the long-term clinical course and prognosis, and, in a randomized trial, the comparative outcomes of two sequences of surgical treatments. Toward these goals, 789 eyes in 591 patients were enrolled at 11 clinical centers between 1988 and 1992. Follow-up will continue until 1996. Eyes were randomly assigned to one of two sequences of surgical treatments. One sequence begins with argon laser trabeculoplasty (ALT), is followed by trabeculectomy, an incisional surgical filtering procedure, should ALT fail to control the disease, and by a second trabeculectomy should the first trabeculectomy fail. The other sequence begins with trabeculectomy, is followed by ALT should the trabeculectomy fail, and by a second trabeculectomy should ALT fail. The main outcome of interest is visual function (visual field and visual acuity). Other important outcomes are intraocular pressure, complications of surgery, time to treatment failure, and extent of need for additional medical therapy. We present in this paper the rationale, objectives, design and methods of the study, and the baseline characteristics of study patients and eyes.

Comparison of analytic algorithms for detecting glaucomatous visual field loss

The sensitivity and specificity of alternate analytic strategies for recognizing glaucomatous visual field loss from automated threshold perimetry (C-30-2 test of the Humphrey Field Analyzer) were compared among one eye each of 106 patients with glaucoma and 249 normal subjects. Algorithms included commercially available global indexes and cross-meridional differences (Statpac 1 and Statpac 2), as well as cross-meridional and cluster analyses that were developed independently for natural history studies and clinical trials. The sensitivity of most algorithms was high, except for those that used only diffuse loss as an indicator of abnormality. Specificity was acceptably high for all algorithms. Subjects who failed to meet the manufacturer's standard for reliability had much reduced specificity, but sensitivity was also affected. Algorithms that were based on any of the alternate definitions of localized reduction in retinal sensitivity performed equally well, which suggests that any of these approaches is useful in searching for glaucomatous visual loss as typified by this database. Availability, familiarity, and convenience may govern the selection of any one analytic approach for use in a particular setting.

A common variant near TGFBR3 is associated with primary open angle glaucoma

Primary open angle glaucoma (POAG), a major cause of blindness worldwide, is a complex disease with a significant genetic contribution. We performed Exome Array (Illumina) analysis on 3504 POAG cases and 9746 controls with replication of the most significant findings in 9173 POAG cases and 26 780 controls across 18 collections of Asian, African and European descent. Apart from confirming strong evidence of association at CDKN2B-AS1 (rs2157719 [G], odds ratio [OR] = 0.71, P = 2.81 × 10(-33)), we observed one SNP showing significant association to POAG (CDC7-TGFBR3 rs1192415, ORG-allele = 1.13, Pmeta = 1.60 × 10(-8)). This particular SNP has previously been shown to be strongly associated with optic disc area and vertical cup-to-disc ratio, which are regarded as glaucoma-related quantitative traits. Our study now extends this by directly implicating it in POAG disease pathogenesis.

ALO 2145 reduces the intraocular pressure elevation after anterior segment laser surgery

The effect of an alpha adrenergic agonist, ALO 2145 (para-amino-clonidine [PAC]), was examined in a double-masked, multicenter study on the postoperative intraocular pressure (IOP) elevation after laser surgery in 165 patients (83 trabeculoplasty, 36 iridotomy, and 46 capsulotomy). One drop of 1.0% ALO 2145 or vehicle was instilled 1 hour before and immediately after laser surgery. The mean IOP increase in the ALO 2145-treated group was lower (P less than 0.05) than in the placebo group at each of the first three postoperative hours. Overall, 18% of placebo-treated eyes experienced IOP increases greater than or equal to 10 mmHg as compared with 4% of ALO 2145-treated eyes (P less than 0.003). Ocular and systemic side effects were minimal and did not differ between the treatment groups. ALO 2145 safely and effectively reduced the incidence and magnitude of potentially harmful IOP elevations after anterior segment laser surgery.

Association of CAV1/CAV2 genomic variants with primary open-angle glaucoma overall and by gender and pattern of visual field loss

PURPOSE

The CAV1/CAV2 (caveolin 1 and caveolin 2) genomic region previously was associated with primary open-angle glaucoma (POAG), although replication among independent studies has been variable. The aim of this study was to assess the association between CAV1/CAV2 single nucleotide polymorphisms (SNPs) and POAG in a large case-control dataset and to explore associations by gender and pattern of visual field (VF) loss further.

DESIGN

Case-control study.

PARTICIPANTS

We analyzed 2 large POAG data sets: the Glaucoma Genes and Environment (GLAUGEN) study (976 cases, 1140 controls) and the National Eye Institute Glaucoma Human Genetics Collaboration (NEIGHBOR) consortium (2132 cases, 2290 controls).

METHODS

We studied the association between 70 SNPs located within the CAV1/CAV2 genomic region in the GLAUGEN and NEIGHBOR studies, both genotyped on the Illumina Human 660WQuadv1C BeadChip array and imputed with the Markov Chain Haplotyping algorithm using the HapMap 3 reference panel. We used logistic regression models of POAG in the overall population and separated by gender, as well as by POAG subtypes defined by type of VF defect (peripheral or paracentral). Results from GLAUGEN and NEIGHBOR were meta-analyzed, and a Bonferroni-corrected significance level of 7.7 × 10(-4) was used to account for multiple comparisons.

MAIN OUTCOME MEASURES

Overall POAG, overall POAG by gender, and POAG subtypes defined by pattern of early VF loss.

RESULTS

We found significant associations between 10 CAV1/CAV2 SNPs and POAG (top SNP, rs4236601; pooled P = 2.61 × 10(-7)). Of these, 9 were significant only in women (top SNP, rs4236601; pooled P = 1.59 × 10(-5)). Five of the 10 CAV1/CAV2 SNPs were associated with POAG with early paracentral VF (top SNP, rs17588172; pooled P = 1.07 × 10(-4)), and none of the 10 were associated with POAG with peripheral VF loss only or POAG among men.

CONCLUSIONS

CAV1/CAV2 SNPs were associated significantly with POAG overall, particularly among women. Furthermore, we found an association between CAV1/CAV2 SNPs and POAG with paracentral VF defects. These data support a role for caveolin 1, caveolin 2, or both in POAG and suggest that the caveolins particularly may affect POAG pathogenesis in women and in patients with early paracentral VF defects.

Laser-induced primate glaucoma. I. Progression of cupping

Sustained intraocular pressure elevations were induced in 15 monkey eyes by argon laser photocoagulation of the trabecular meshwork. Large fluctuations of IOP resulted. Posttreatment gonioscopy revealed an open angle with scattered low peripheral anterior synechiae. Optic disc cupping progressed during pressure elevations, manifested first as posterior bowing of the optic nerve head and peripapillary tissues. Reversal of this early phase of cupping occurred in eight eyes during spontaneous normalization of IOP. In most eyes, as cupping evolved from saucerization to a deeper cup, the cup remained round. In four eyes, focal sloping of the cup to the inferotemporal rim occurred with nerve fiber layer defects. Total cupping with undermining of the rim occurred in five eyes with prolonged IOP elevation. Laser-induced primate glaucoma has features in common with juvenile human glaucoma and is a useful model for the study of cupping of the optic nerve head.

Investigation of known genetic risk factors for primary open angle glaucoma in two populations of African ancestry

PURPOSE

Multiple genes have been associated with primary open angle glaucoma (POAG) in Caucasian populations. We now examine the association of these loci in populations of African ancestry, populations at particularly high risk for POAG.

METHODS

We genotyped DNA samples from two populations: African American (1150 cases and 999 controls) and those from Ghana, West Africa (483 cases and 593 controls). Our analysis included 57 single nucleotide polymorphisms (SNPs) in five loci previously associated with POAG at the genome-wide level, including CDKN2B-AS1, TMCO1, CAV1/CAV2, chromosome 8q22 intergenic region, and SIX1/SIX6. We evaluated association in the full datasets, as well as subgroups with normal pressure glaucoma (NPG, maximum IOP ≤21 mm Hg) and high pressure glaucoma (HPG, IOP >21 mm Hg).

RESULTS

In African Americans, we identified an association of rs10120688 in the CDNK2B-AS1 region with POAG (P = 0.0020). Several other SNPs were nominally associated, but did not survive correction for multiple testing. In the subgroup analyses, significant associations were identified for rs10965245 (P = 0.0005) in the CDKN2B-AS1 region with HPG and rs11849906 in the SIX1/SIX6 region with NPG (P = 0.006). No significant association was identified with any loci in the Ghanaian samples.

CONCLUSIONS

POAG genetic susceptibility alleles associated in Caucasians appear to play a greatly reduced role in populations of African ancestry. Thus, the major genetic components of POAG of African origin remain to be identified. This finding underscores the critical need to pursue large-scale genome-wide association studies in this understudied, yet disproportionately affected population.

Prediction of Visual Field Progression in Glaucoma

PURPOSE

To determine the probability of future glaucomatous visual field (VF) progression with clinical and perimetric data.

METHODS

One hundred sixty-one eyes of patients (161) enrolled in the Advanced Glaucoma Intervention Study (AGIS) with >or=8 years of follow-up and a baseline VF score <or=16 were selected. VF progression at 8 years was determined with point-wise linear regression (PLR) analysis, using a two-omitting algorithm. The course of VF series over the first 4 years of follow-up was quantified by an index, the sum of slopes, which is the sum of all slopes of VF thresholds with P < 0.05 when PLR was performed on the 4-year data. The following parameters were included in a logistic regression model to predict 8-year outcomes from the first 4 years of follow-up: intervention sequence, age, AGIS VF score, mean IOP, IOP fluctuation, and sum of slopes.

RESULTS

Sixty-four (40%) eyes progressed after 8 years as determined by PLR analysis. Two parameters were predictive of subsequent VF progression, as identified at 8 years (predictive power: 76%): more negative sum of slopes (i.e., faster or more extensive deterioration; P < 0.001) and older age at 4 years (P = 0.049). When sum of slopes alone was used to predict outcomes at 8 years, the predictive power was the same.

CONCLUSIONS

The VF sum of slopes can be used to estimate the probability of subsequent VF worsening with reasonable, clinically useful accuracy. This probability may be combined with other clinical information for more effective clinical predictions and treatment decisions.

CDKN2B-AS1 genotype-glaucoma feature correlations in primary open-angle glaucoma patients from the United States

PURPOSE

To assess the association between single nucleotide polymorphisms (SNPs) of the gene region containing cyclin-dependent kinase inhibitor 2B antisense noncoding RNA (CDKN2B-AS1) and glaucoma features among primary open-angle glaucoma (POAG) patients.

DESIGN

Retrospective observational case series.

METHODS

We studied associations between 10 CDKN2B-AS1 SNPs and glaucoma features among 976 POAG cases from the Glaucoma Genes and Environment (GLAUGEN) study and 1971 cases from the National Eye Institute Glaucoma Human Genetics Collaboration (NEIGHBOR) consortium. For each patient, we chose the feature from the eye with the higher value. We created cohort-specific multivariable models for glaucoma features and then meta-analyzed the results.

RESULTS

For 9 of the 10 protective CDKN2B-AS1 SNPs with minor alleles associated with reduced disease risk (eg, the G allele at rs2157719), POAG patients carrying these minor alleles had smaller cup-to-disc ratio (0.05 units smaller per G allele at diagnosis; 95% CI: -0.08, -0.03; P = 6.23E-05) despite having higher intraocular pressure (IOP) (0.70 mm Hg higher per G allele at DNA collection; 95% CI: 0.40, 1.00; P = 5.45E-06). For the 1 adverse rs3217992 SNP with minor allele A associated with increased disease risk, POAG patients with A alleles had larger cup-to-disc ratio (0.05 units larger per A allele at diagnosis; 95% CI: 0.02, 0.07; P = 4.74E-04) despite having lower IOP (-0.57 mm Hg per A allele at DNA collection; 95% CI: -0.84, -0.29; P = 6.55E-05).

CONCLUSION

Alleles of CDKN2B-AS1 SNPs, which influence risk of developing POAG, also modulate optic nerve degeneration among POAG patients, underscoring the role of CDKN2B-AS1 in POAG.

Visual field changes after cataract extraction: the AGIS experience

PURPOSE

To test the hypothesis that cataract extraction in glaucomatous eyes improves overall sensitivity of visual function without affecting the size or depth of glaucomatous scotomas.

DESIGN

Experimental study with no control group.

METHODS

One hundred fifty-eight eyes (of 140 patients) from the Advanced Glaucoma Intervention Study with at least two reliable visual fields within a year both before and after cataract surgery were included. Average mean deviation (MD), pattern standard deviation (PSD), and corrected pattern standard deviation (CPSD) were compared before and after cataract extraction. To evaluate changes in scotoma size, the number of abnormal points (P < .05) on the pattern deviation plot was compared before and after surgery. We described an index ("scotoma depth index") to investigate changes of scotoma depth after surgery.

RESULTS

Mean values for MD, PSD, and CPSD were -13.2, 6.4, and 5.9 dB before and -11.9, 6.8, and 6.2 dB after cataract surgery (P < or = .001 for all comparisons). Mean (+/- SD) number of abnormal points on pattern deviation plot was 26.7 +/- 9.4 and 27.5 +/- 9.0 before and after cataract surgery, respectively (P = .02). Scotoma depth index did not change after cataract extraction (-19.3 vs -19.2 dB, P = .90).

CONCLUSIONS

Cataract extraction caused generalized improvement of the visual field, which was most marked in eyes with less advanced glaucomatous damage. Although the enlargement of scotomas was statistically significant, it was not clinically meaningful. No improvement of sensitivity was observed in the deepest part of the scotomas.

Baseline visual field characteristics in the ocular hypertension treatment study

PURPOSE

The Ocular Hypertension Treatment Study (OHTS) seeks to evaluate the safety and efficacy of topical ocular hypotensive medication in preventing or delaying the onset of visual field loss and/or optic nerve damage in ocular hypertensive subjects at risk for developing primary open-angle glaucoma. This study evaluates the baseline visual field test characteristics (visual field status, reliability properties, etc.) of patients who underwent eligibility visual field testing for entry to the OHTS.

DESIGN

Cross-sectional study of baseline data as part of a longitudinal randomized clinical trial.

PARTICIPANTS

Two thousand eight hundred nineteen ocular hypertensive individuals, aged 40 to 80 (mean age, 55).

METHODS

Subjects underwent at least two Humphrey Field Analyzer Program 30-2 Full Threshold visual field examinations in both eyes for study eligibility. A third examination was performed if a prior test was abnormal, questionable, or unreliable. For final eligibility, two sets of visual field examinations had to meet OHTS criteria for reliability and had to be classified as "normal." All OHTS visual field tests of potential subjects were submitted for eligibility assessment to the OHTS Visual Field Reading Center.

MAIN OUTCOME MEASURES

The percentage of visual fields that were normal and reliable according to OHTS criteria.

RESULTS

Of the subset of 2304 subjects who completed the eligibility assessments, 1828 (79%) were OHTS-eligible based on visual field test requirements. A third eligibility test was required for 11% of all eyes because of unreliable, questionable, or abnormal test results. With the 33% fixation loss cutoff in the OHTS, 97% of all eligibility visual field examinations were reliable and 3% were unreliable. The most frequent cause (69.5%) of unreliability was excessive fixation losses.

CONCLUSIONS

Permitting one repeat test after an abnormal or unreliable test allowed an extra 560 patients to be "eligible" for the study based on visual field tests. A clinical screening review of otherwise normal and reliable tests was not restrictive. The adoption of a 33% fixation loss cutoff significantly reduced the number of required retests and prevented study rejection of 89 patients.

Pointwise Linear Regression for Evaluation of Visual Field Outcomes and Comparison With the Advanced Glaucoma Intervention Study Methods

OBJECTIVE

To investigate pointwise linear regression (PLR) for longitudinal evaluation of visual fields and to compare results with those of the Advanced Glaucoma Intervention Study (AGIS) criteria.

METHODS

We selected 509 eyes (401 patients) from the AGIS with 3 or more years of follow-up, 7 or more visual field examinations, and an AGIS reference score of 16 or lower. Visual field change at test locations was defined as a change of threshold sensitivity of 1 dB/y or higher and P<or=.01. Several sets of criteria were investigated for defining change of visual field series with PLR.

MAIN OUTCOME MEASURES

Progression or improvement of visual field series with PLR and AGIS criteria.

RESULTS

Mean (SD) follow-up time and baseline AGIS score were 7.4 (1.7) years and 7.7 (4.4), respectively. Pairwise agreement between AGIS and various PLR criteria ranged from 52% to 64% with the kappa statistic varying between 0.22 (95% confidence interval, 0.15-0.29) and 0.30 (95% confidence interval, 0.22-0.38). One hundred thirty-eight (27%) and 151 (30%) eyes progressed (85 eyes or 17% detected by both methods) while 72 (14%) and 11 (2%) eyes improved (5 eyes or 1% detected by both methods) based on AGIS and the most rigorous PLR criteria, respectively.

CONCLUSIONS

Based on rigorous, clinically relevant criteria, PLR detects progression in a similar proportion of eyes compared with AGIS criteria. Pointwise linear regression may be superior to AGIS methods since it identifies fewer visual field series as improving.

Genome-wide analysis of central corneal thickness in primary open-angle glaucoma cases in the NEIGHBOR and GLAUGEN consortia

PURPOSE

To investigate the effects of central corneal thickness (CCT)-associated variants on primary open-angle glaucoma (POAG) risk using single nucleotide polymorphisms (SNP) data from the Glaucoma Genes and Environment (GLAUGEN) and National Eye Institute (NEI) Glaucoma Human Genetics Collaboration (NEIGHBOR) consortia.

METHODS

A replication analysis of previously reported CCT SNPs was performed in a CCT dataset (n = 1117) and these SNPs were then tested for association with POAG using a larger POAG dataset (n = 6470). Then a CCT genome-wide association study (GWAS) was performed. Top SNPs from this analysis were selected and tested for association with POAG. cDNA libraries from fetal and adult brain and ocular tissue samples were generated and used for candidate gene expression analysis.

RESULTS

Association with one of 20 previously published CCT SNPs was replicated: rs12447690, near the ZNF469 gene (P = 0.001; β = -5.08 μm/allele). None of these SNPs were significantly associated with POAG. In the CCT GWAS, no SNPs reached genome-wide significance. After testing 50 candidate SNPs for association with POAG, one SNP was identified, rs7481514 within the neurotrimin (NTM) gene, that was significantly associated with POAG in a low-tension subset (P = 0.00099; Odds Ratio [OR] = 1.28). Additionally, SNPs in the CNTNAP4 gene showed suggestive association with POAG (top SNP = rs1428758; P = 0.018; OR = 0.84). NTM and CNTNAP4 were shown to be expressed in ocular tissues.

CONCLUSIONS

The results suggest previously reported CCT loci are not significantly associated with POAG susceptibility. By performing a quantitative analysis of CCT and a subsequent analysis of POAG, SNPs in two cell adhesion molecules, NTM and CNTNAP4, were identified and may increase POAG susceptibility in a subset of cases.

Ocular irritation from high-dose methotrexate therapy: pharmacokinetics of drug in the tear film

Four of 13 patients receiving intermittent high-dose methotrexate therapy experienced recurrent symptoms of ocular irritation (burning, pruritus, "dry eyes") two to seven days after chemotherapy. Ophthalmic examination was unremarkable in symptomatic individuals except for decreased reflex production of tears in some patients. Pharmacokinetic studies of a group of these patients revealed concentrations of methotrexate in tears equivalent to those in plasma at 24 and 48 hours after treatment; these concentrations reached 1 X 10(-5) M during the infusion of methotrexate. The occurrence of acidic lacrimal secretions, pH 6.5 in one symptomatic patient, may have contributed to decreased solubility of methotrexate in the fluid of the conjunctival sac.

The Advanced Glaucoma Intervention Study (AGIS): 5. Encapsulated bleb after initial trabeculectomy

PURPOSE

To compare the incidence of encapsulated bleb after trabeculectomy in eyes with and without previous argon laser trabeculoplasty and to assess other risk factors for encapsulated bleb development.

METHODS

After medical treatment failure, eyes enrolled in the Advanced Glaucoma Intervention Study (AGIS) were randomly assigned to sequences of interventions starting with either argon laser trabeculoplasty or trabeculectomy. In the present study we compared the clinical course for 1 year after trabeculectomy in 119 eyes with failed argon laser trabeculoplasty with that of 379 eyes without previous argon laser trabeculoplasty. Data on bleb encapsulation were collected at the time that the encapsulation was diagnosed, and 3 and 6 months later.

RESULTS

Of multiple factors examined in the AGIS data for the risk of developing encapsulated bleb, only male gender and high school graduation without further formal education were statistically significant. Encapsulation occurred in 18.5% of eyes with previous argon laser trabeculoplasty failure and 14.5% of eyes without previous argon laser trabeculoplasty (unadjusted relative risk, 1.27; 95% confidence limits = 0.81, 2.00; P = .23). After adjusting for age, gender, educational achievement, prescribed systemic beta-blockers, diabetes, visual field score, and years since glaucoma diagnosis, this difference remains statistically not significant. Four weeks after trabeculectomy, mean intraocular pressure was 7.5 mm Hg higher in eyes with (22.5 mm Hg) than without (15.0 mm Hg) encapsulated bleb; at 1 year after trabeculectomy and the resumption of medical therapy when needed, this excess was reduced to 1.4 mm Hg.

CONCLUSIONS

This study, as did two previous studies, found male gender to be a risk factor for bleb encapsulation. Four studies, including the present study, have reported a higher rate of encapsulation in eyes with previous argon laser trabeculoplasty; in two of the studies, one of which was the present study, the rate was not statistically significantly higher; in the other two studies the rate was significantly higher. The 4-week postoperative mean intraocular pressure was higher in eyes with than without encapsulated bleb; with the resumption of medical treatment the two means converged after 1 year.

Association of Genetic Variants With Primary Open-Angle Glaucoma Among Individuals With African Ancestry

Importance

Primary open-angle glaucoma presents with increased prevalence and a higher degree of clinical severity in populations of African ancestry compared with European or Asian ancestry. Despite this, individuals of African ancestry remain understudied in genomic research for blinding disorders.

Objectives

To perform a genome-wide association study (GWAS) of African ancestry populations and evaluate potential mechanisms of pathogenesis for loci associated with primary open-angle glaucoma.

Design, Settings, and Participants

A 2-stage GWAS with a discovery data set of 2320 individuals with primary open-angle glaucoma and 2121 control individuals without primary open-angle glaucoma. The validation stage included an additional 6937 affected individuals and 14 917 unaffected individuals using multicenter clinic- and population-based participant recruitment approaches. Study participants were recruited from Ghana, Nigeria, South Africa, the United States, Tanzania, Britain, Cameroon, Saudi Arabia, Brazil, the Democratic Republic of the Congo, Morocco, Peru, and Mali from 2003 to 2018. Individuals with primary open-angle glaucoma had open iridocorneal angles and displayed glaucomatous optic neuropathy with visual field defects. Elevated intraocular pressure was not included in the case definition. Control individuals had no elevated intraocular pressure and no signs of glaucoma.

Exposures

Genetic variants associated with primary open-angle glaucoma.

Main Outcomes and Measures

Presence of primary open-angle glaucoma. Genome-wide significance was defined as P < 5 × 10-8 in the discovery stage and in the meta-analysis of combined discovery and validation data.

Results

A total of 2320 individuals with primary open-angle glaucoma (mean [interquartile range] age, 64.6 [56-74] years; 1055 [45.5%] women) and 2121 individuals without primary open-angle glaucoma (mean [interquartile range] age, 63.4 [55-71] years; 1025 [48.3%] women) were included in the discovery GWAS. The GWAS discovery meta-analysis demonstrated association of variants at amyloid-β A4 precursor protein-binding family B member 2 (APBB2; chromosome 4, rs59892895T>C) with primary open-angle glaucoma (odds ratio [OR], 1.32 [95% CI, 1.20-1.46]; P = 2 × 10-8). The association was validated in an analysis of an additional 6937 affected individuals and 14 917 unaffected individuals (OR, 1.15 [95% CI, 1.09-1.21]; P < .001). Each copy of the rs59892895*C risk allele was associated with increased risk of primary open-angle glaucoma when all data were included in a meta-analysis (OR, 1.19 [95% CI, 1.14-1.25]; P = 4 × 10-13). The rs59892895*C risk allele was present at appreciable frequency only in African ancestry populations. In contrast, the rs59892895*C risk allele had a frequency of less than 0.1% in individuals of European or Asian ancestry.

Conclusions and Relevance

In this genome-wide association study, variants at the APBB2 locus demonstrated differential association with primary open-angle glaucoma by ancestry. If validated in additional populations this finding may have implications for risk assessment and therapeutic strategies.

Threshold for retinal damage associated with the use of high-power neodymium-YAG lasers in the vitreous

Ultrashort, Q-switched or mode-locked, neodymium-YAG laser pulses focused within 2 mm of the retina caused reproducible retinal damage in four eyes of two monkeys and in four eyes of three rabbits. The distance of the laser focus from the retina for clinically observed threshold retinal damage was characterized for pulse energies up to 9 mJ. For the 2- to 6-mJ pulse energies necessary to rupture vitreal membranes in clear media in rabbits, the high-power laser pulses could not be focused within 2 mm of the retina without substantial risk of damaging the underlying retina. These laser pulses did not rupture vitreal membranes in hazy ocular media that prevented precise focusing. The retinal damage was somewhat greater than expected for retinal absorption of 1.06-micron laser energy, suggesting that secondary effects such as self-focusing and shock waves emanating from the focus may be important.

A Common Variant in MIR182 Is Associated With Primary Open-Angle Glaucoma in the NEIGHBORHOOD Consortium

PURPOSE

Noncoding microRNAs (miRNAs) have been implicated in the pathogenesis of glaucoma. We aimed to identify common variants in miRNA coding genes (MIR) associated with primary open-angle glaucoma (POAG).

METHODS

Using the NEIGHBORHOOD data set (3853 cases/33,480 controls with European ancestry), we first assessed the relation between 85 variants in 76 MIR genes and overall POAG. Subtype-specific analyses were performed in high-tension glaucoma (HTG) and normal-tension glaucoma subsets. Second, we examined the expression of miR-182, which was associated with POAG, in postmortem human ocular tissues (ciliary body, cornea, retina, and trabecular meshwork [TM]), using miRNA sequencing (miRNA-Seq) and droplet digital PCR (ddPCR). Third, miR-182 expression was also examined in human aqueous humor (AH) by using miRNA-Seq. Fourth, exosomes secreted from primary human TM cells were examined for miR-182 expression by using miRNA-Seq. Fifth, using ddPCR we compared miR-182 expression in AH between five HTG cases and five controls.

RESULTS

Only rs76481776 in MIR182 gene was associated with POAG after adjustment for multiple comparisons (odds ratio [OR] = 1.23, 95% confidence interval [CI]: 1.11-1.42, P = 0.0002). Subtype analysis indicated that the association was primarily in the HTG subset (OR = 1.26, 95% CI: 1.08-1.47, P = 0.004). The risk allele T has been associated with elevated miR-182 expression in vitro. Data from ddPCR and miRNA-Seq confirmed miR-182 expression in all examined ocular tissues and TM-derived exosomes. Interestingly, miR-182 expression in AH was 2-fold higher in HTG patients than nonglaucoma controls (P = 0.03) without controlling for medication treatment.

CONCLUSIONS

Our integrative study is the first to associate rs76481776 with POAG via elevated miR-182 expression.

Experimental ciliochoroidal detachment. Effect on intraocular pressure and aqueous humor flow

Ciliochoroidal detachments were produced in rhesus monkeys by injecting glutathione bicarbonate Ringer's solution, autologous serum, or silicone oil into the anterior suprachoroidal space. Silicone oil detachments, like sham operations, caused a transient 2 mm Hg reduction in intraocular pressure. Detachments with glutathione bicarbonate Ringer's solution or serum caused a 6 mm Hg reduction in intraocular pressure, which normalized in three weeks. Aqueous humor flow in serum-detached eyes was normal, indicating that the hypotonia does not result from reduced aqueous humor formation. Blood was present in Schlemm's canal in most eyes with hypotonia, which suggests that hypotonia is not the result of enhanced conventional aqueous humor outflow. Therefore, it is postulated that hypotonia might result from enhanced aqueous humor outflow from the anterior chamber into the suprachoroidal space and out of the eye through the emissarial channels of the sclera (uveoscleral outflow).

Ah locus: genetic differences in susceptibility to cataracts induced by acetaminophen

The Ahb/Ahb homozygous and the Ahb/Ahd heterozygous inbred mouse strains from the (C57BL/6)(DBA/2)F1 X DBA/2 backcross are genetically responsive to 3-methylcholanthrene. They both also develop, within 6 hours after a large intraperitoneal dose of acetaminophen, an irreversible opacity in the anterior portion of the lens. Such cataract formation does not occur in similarly treated nonresponsive inbred strains or nonresponsive Ahd/Ahd individuals from the same backcross. Differences in acetaminophen metabolism and toxicity are associated with the Ah locus in the mouse, and differences in heritability at the Ah locus exist in the human. Our ophthalmologic findings may be important clinically to certain patients receiving either a single large overdose of this drug or high doses over a long period.