Severe myopia as a risk factor for progressive visual field loss in primary open-angle glaucoma

Impact of Age and Myopia on the Rate of Visual Field Progression in Glaucoma Patients

Myopia is rapidly increasing in young populations and patients with glaucoma associated with myopia are reported to be young aged in East Asia. These young patients have a longer life expectancy, which increases their risk of end-of-life visual disabilities. There is a need to understand the clinical course of myopic glaucoma patients, which may be important for the care of these myopic populations. In this study, we evaluated the relationship between the age at presentation and the rate of glaucoma progression in the visual field (VF) according to the presence of myopia. The study was conducted as a prospective observational study including 179 patients with open-angle glaucoma who had undergone at least 5 VF examinations with a follow-up of at least 5 years. The progression rate of the mean deviation (MD) and the pattern standard deviation (PSD) are expressed as change in decibels (dB) per year. The slopes of the MD and PSD were calculated by linear regression analyses. Factors related to the slope of VF MD changes were analyzed with correlation and regression analyses. The slope of the linear fit line plotted against age at presentation and the rate of change in the VF MD was -0.026 (P < 0.001) in the myopic group and -0.008 (P = 0.167) in the nonmyopic group; the relationship was more prominent in the myopic group than the nonmyopic group. In the myopic group, age (β = -0.417; 95% confidence intervals (CI), -0.651 to -0.200; P = 0.050) and baseline untreated intraocular pressure (β = -0.179; 95% CI, -0.331 to -0.028; P = 0.022) were significantly related to the rate of change in the MD, which was only the presence of disc hemorrhage (β = -0.335; 95% CI, -0.568 to -0.018; P = 0.022) in the nonmyopic group. Age at presentation was significantly related to the rate of change in the VF in glaucomatous eyes with myopia compared to eyes without myopia. Older age was significantly related to the rate of change in the VF only in myopic glaucomatous eyes.

Progression of primary open angle glaucoma in asymmetrically myopic eyes

PURPOSE

To compare progression of primary open angle glaucoma (POAG) in asymmetrically myopic eyes within the same subject and evaluate whether the degree of myopia is related to glaucoma progression.

METHODS

POAG patients with asymmetric myopia (axial length [AXL] ≥24 mm in both eyes, and the AXL difference between the right and left eyes to be ≥0.5 mm) were included. Glaucoma progression was determined either by optic disc/retinal nerve fiber layer (RNFL) photographs or by serial visual field (VF) data. The progression rates of VF mean deviation (dB/year) and spectral domain optical coherence tomography measured RNFL thickness (μm/year) were compared between the more myopic eye (MME) and the less myopic eye (LME) within the same subject.

RESULTS

A total of 55 patients (mean follow up period; 4.5 ± 1.0 years) were included. The mean AXL demonstrated a significant difference between MME and LME (26.3 ± 1.7 vs. 25.6 ± 1.7 mm; p = 0.036). The mean baseline VF MD (-3.8 ± 5.4 vs. -2.6 ± 4.7 dB; p = 0.21) and average RNFL thickness (77.5 ± 10.6 vs. 79.9 ± 12.3 μm; p = 0.36) did not differ between the MME and LME. Among the 55 patients, optic disc/RNFL photographic progression was noted in the MME in 15 patients, in the LME in 19 patients, and in both eyes in seven patients. VF progression was noted in the MME in seven patients, in the LME in seven patients, and in both eyes in four patients. The VF MD progression rates were -0.25 ± 0.34 dB/year in MME and -0.26 ± 0.34 dB/year in LME cases (p = 0.91). The mean progression rate of the average RNFL thickness also did not differ between the MME and LME (-0.59 ± 0.67 vs. -0.66 ± 0.72 μm/year, p = 0.68).

CONCLUSIONS

The degree of myopia was not associated with glaucoma progression when assessing the same patient using either the VF or optic disc/RNFL criteria in asymmetrically myopic patients.

Rate of progression of total, upper, and lower visual field defects in patients with open-angle glaucoma and high myopia

PURPOSE

We evaluated the rate of progression of total, upper, and lower visual field defects in patients with treated primary open-angle glaucoma (POAG) with high myopia (HM).

SUBJECTS AND METHODS

Seventy eyes of 70 POAG patients with HM [≤-8 diopters (D)] were examined. The mean deviation (MD) slope and the upper and lower total deviation (upper TD, lower TD) slopes of the Humphrey Field Analyzer were calculated in patients with high-tension glaucoma (HTG) (>21 mmHg) versus normal-tension glaucoma (NTG) (≤21 mmHg). The mean age of all the patients (29 eyes with HTG and 41 eyes with NTG) was 48.5 ± 9.6 years. The MD slope, and upper and lower TD slopes of the HM group were compared to those of the non-HM group (NHM) (>-8 D) selected from 544 eyes in 325 age-matched POAG patients. In all, 70 eyes with HM and NHM were examined.

RESULTS

The mean MD slope was -0.33 ± 0.33 dB/year in the HM, and -0.38 ± 0.49 dB/year in the NHM. There were no statistical differences between the HM and NHM (p = 0.9565). In the comparison of HTG versus NTG patients in both groups, the MD slope, and upper and lower TD slopes were similar.

CONCLUSIONS

The rate of progression of total, upper, and lower visual field defects was similar among patients with HM and NHM. Although HM is a risk factor for the onset of glaucoma, HM may not be a risk factor for progression of visual field defects as assessed by the progression rate under treatment.

Glaucomatous-Type Optic Discs in High Myopia

Purpose

To assess the prevalence of glaucoma in patients with high myopia defined as myopic refractive error of >-8 diopters or axial length ≥26.5 mm.

Methods

The hospital-based observational study included 172 patients (336 eyes) with a mean age of 61.9±12.3 years and mean axial length of 30.1±2.3 mm (range: 24.7–39.1mm). Glaucomatous-type optic discs were defined by glaucomatous optic disc appearance. Glaucoma was defined by glaucomatous optic disc appearance and glaucomatous Goldmann visual field defects not corresponding with myopic macular changes.

Results

Larger disc area (mean: 3.18±1.94 mm²) was associated with longer axial length (P<0.001; standardized correlation coefficient: 0.45). Glaucoma was detected in 94 (28%; 95% Confidence intervals: 23%, 33%) eyes. In multivariate analysis, glaucoma prevalence was 3.2 times higher (P<0.001) in megalodiscs (>3.79 mm²) than in normal-sized discs or small discs (<1.51 mm²) after adjusting for older age. Axial length was not significantly (P = 0.38) associated with glaucoma prevalence in that model. Glaucoma prevalence increased by a factor of 1.39 for each increase in optic disc area by one mm². Again, axial length was not significantly (P = 0.38) associated with glaucoma prevalence when added to this multivariate model.

Conclusion

Within highly myopic individuals, glaucoma prevalence increased with larger optic disc size beyond a disc area of 3.8 mm². Highly myopic megalodiscs as compared to normal sized discs or small discs had a 3.2 times higher risk for glaucomatous optic nerve neuropathy. The increased glaucoma prevalence in axial high myopia was primarily associated with axial myopia associated disc enlargement and not with axial elongation itself.

Axial Myopia Is Associated with Visual Field Prognosis of Primary Open-Angle Glaucoma

Purpose

To identify whether myopia was associated with the visual field (VF) progression of primary open-angle glaucoma (POAG).

Methods

A total of 270 eyes of 270 POAG followed up for more than 3 years with ≥9 reliable VFs by Octopus perimetry were retrospectively reviewed. Myopia was divided into: mild myopia (-2.99 diopter [D], 0), moderate myopia (-5.99, 3.00 D), marked myopia (-9.00, -6.00 D) and non-myopia (0 D or more). An annual change in the mean defect (MD) slope >0.22 dB/y and 0.30 dB/y was defined as fast progression, respectively. Logistic regression was performed to determine prognostic factors for VF progression.

Results

For the cutoff threshold at 0.22 dB/y, logistic regression showed that vertical cup-to-disk ratio (VCDR; p = 0.004) and the extent of myopia (p = 0.002) were statistically significant. When logistic regression was repeated after excluding the extent of myopia, axial length (AL; p = 0.008, odds ratio [OR] = 0.796) reached significance, as did VCDR (p = 0.001). Compared to eyes with AL≤23 mm, the OR values were 0.334 (p = 0.059), 0.309 (p = 0.044), 0.266 (p = 0.019), 0.260 (p = 0.018), respectively, for 23 <AL≤24 mm, 24 <AL≤25 mm, 25 <AL ≤26 mm, and AL>26 mm. The significance of vertical cup-to-disk ratio of (p = 0.004) and the extent of myopia (p = 0.008) did not change for the cutoff threshold at 0.30dB/y.

Conclusions

VCDR and myopia were associated with VF prognosis of POAG. Axial myopia may be a protective factor against VF progression.

Relationship between progression of visual field defect and intraocular pressure in primary open-angle glaucoma

Purpose

To analyze the relationship between intraocular pressure (IOP) and the progression of visual field defects in Japanese primary open-angle glaucoma (POAG) and normal-tension glaucoma (NTG) patients.

Patients and methods

The subjects of the study were patients undergoing treatment for POAG or NTG who had performed visual field tests at least ten times with a Humphrey field analyzer (Swedish interactive thresholding algorithm standard, C30-2 program). The progression of visual field defects was defined by a significantly negative value of the mean deviation slope at the final visual field test during the follow-up period. The relationships between the progression of visual field defects and IOP, as well as other clinical factors, were retrospectively analyzed.

Results

A total of 156 eyes of 156 patients were included in the analysis. Significant progression of visual field defects was observed in 70 eyes of 70 patients (44.9%), while no significant progression was evident in 86 eyes of 86 patients (55.1%). The eyes with visual field defect progression had significantly lower baseline IOP (P<0.05), as well as significantly lower IOP reduction rate (P<0.01). The standard deviation of IOP values during follow-up was significantly greater in the eyes with visual field defect progression than in eyes without (P<0.05).

Conclusion

Reducing IOP is thought to be useful for Japanese POAG or NTG patients to suppress the progression of visual field defects. In NTG, IOP management should take into account not only achieving the target IOP, but also minimizing the fluctuation of IOP during follow-up period.

Intraocular Pressure Evaluation after Myopic Refractive Surgery: A Comparison of Methods in 121 Eyes

PURPOSE

To compare nine different formulas, developed to overcome the underestimation of intraocular pressure (IOP) readings after myopic photorefractive keratectomy (PRK).

METHODS

The correlations between the modified IOP and the preoperative ones in 121 eyes of 72 patients who underwent myopic PRK were evaluated.

RESULTS

The correlation and percentage of eyes in the range of ±2 mmHg were: Emara (R(2) = 0.1686, 74%), Munger (R(2) = 0.1665, 71%), Rosa (R(2) = 0.2489, 82%), Rashad (R(2) = 0.8593, 47%), Duch (R(2) = 0.1631, 82%), Arimoto (R(2) = 0.1638, 77%), Chihara (R(2) = 0.5389, 80%), Svedberg (R(2) = 0.1269, 54%), Kohlhaas (R(2) = 0.1074, 77%). In the case of known preoperative IOP, combining Rashad and Chihara's formulas (R(2) = 0.7730, 97%) were obtained. In the case of unknown preoperative IOP, combining Rosa and Duch's formulas (R(2) = 0.2484, 84%) were obtained.

CONCLUSION

Our results suggest calculating IOP with the average of Rashad and Chihara's formulas if the preoperative IOP is known and the average of Rosa and Duch's formulas if it is unknown.

Family-based analysis identified CD2 as a susceptibility gene for primary open angle glaucoma in Chinese Han population

Primary open angle glaucoma (POAG) is characterized by optic disc cupping and irreversible loss of retinal ganglion cells. Few genes have been detected that influence POAG susceptibility and little is known about its genetic architecture. In this study, we employed exome sequencing on three members from a high frequency POAG family to identify the risk factors of POAG in Chinese population. Text-mining method was applied to identify genes associated with glaucoma in literature, and protein-protein interaction networks were constructed. Furthermore, reverse transcription PCR and Western blot were performed to confirm the differential gene expression. Six genes, baculoviral inhibitors of apoptosis protein repeat containing 6 (BIRC6), CD2, luteinizing hormone/choriogonadotropin receptor (LHCGR), polycystic kidney and hepatic disease gene 1 (PKHD1), phenylalanine hydroxylase (PAH) and fucosyltransferase 7 (FUT7), which might be associated with POAG, were identified. Both the mRNA expression levels and protein expression levels of HSP27 were increased in astrocytes from POAG patients compared with those from normal control, suggesting that mutation in CD2 might pose a risk for POAG in Chinese population. In conclusion, novel rare variants detected by exome sequencing may hold the key to unravelling the remaining contribution of genetics to complex diseases such as POAG.

Comparison of localized retinal nerve fiber layer defects in highly myopic, myopic, and non-myopic patients with normal-tension glaucoma: a retrospective cross-sectional study

BACKGROUND

The purpose of this study was to evaluate the relationship between patterns of localized retinal nerve fiber layer (RNFL) defects and the degree of myopia in patients with normal-tension glaucoma (NTG).

METHODS

We retrospectively reviewed medical records of patients with high myopia (42 eyes; spherical equivalent [SE] < -6.0 diopters [D]), low to moderate myopia (93 eyes; SE -6.0D ~ and -0.5D), and emmetropia (65 eyes; SE -0.5D ~ +0.5D), all of which were diagnosed as having NTG with localized RNFL defects. On RNFL photographs, the proximity of the RNFL defect to the center of the fovea (angle I) and the sum of the angular width of the defects (angle II) were determined. The patterns of localized RNFL defects were then compared with respect to differences in angles I and II.

RESULTS

Angle I was significantly smaller in the high myopia group than in the low to moderate myopia group (p = 0.028) and the emmetropia group (p = 0.044), while angle II was significantly larger in the high myopia group compared with the low to moderate myopia group and the emmetropia group (p < 0.001, p = 0.007).

CONCLUSIONS

Among subjects with NTG, localized RNFL defects are wider and closer to the fovea in eyes with high myopia than those with low to moderate myopia or emmetropia.

Correlation between central corneal thickness and myopia in Taiwan

The aim of the study was to explore the correlation between central corneal thickness (CCT) and the degree of myopia in Taiwanese adults. A total of 528 individuals were enrolled to undergo myopic laser refractive surgery from January 2004 to December 2006. Preoperative CCT was measured using the Orbscan corneal topography system and refractive status was determined by cycloplegic spherical equivalent. The relationship between CCT and refractive error was investigated by interindividual and intraindividual analyses. Participants had a mean age of 34.8 ± 7.3 years, and 79.9% were female. The mean refractive error was -7.27 ± 2.96 diopters and the mean CCT measurement was 560 ± 35 μm. CCT revealed that there was no association with age. However, CCT was significantly (p = 0.012) less in females than in males. The CCT also showed no significant association with refractive error (p = 0.49). Among the 67 participants with myopic anisometropia, the mean difference between both eyes was 3.09 ± 1.06 diopters. There was no association between the intereye CCT difference and refractive error (p = 0.57). The results remained the same after adjusting for age and sex. In conclusion, there was no correlation between CCT and the degree of myopia among adults in Taiwan. These data might contribute to the ongoing discussion about the role of CCT in the higher incidence of development and progression of glaucoma in myopic individuals.

Macular imaging in highly myopic eyes with and without glaucoma

PURPOSE

To determine how evaluations of macular structures on spectral-domain optical coherence tomography compare with those of the optic disc and circumpapillary retinal nerve fiber layer (RNFL) in discriminating between highly myopic eyes with and without glaucoma.

DESIGN

Retrospective, comparative study.

METHODS

The appearances of ganglion cell layer and RNFL on Spectralis macular scans (Heidelberg Engineering) and optic disc on photographs were evaluated by 2 observers. The receiver operating characteristic regression was conducted for macular ganglion cell complex and circumpapillary RNFL measurements on RTVue-100 (Optovue).

RESULTS

Ninety highly myopic eyes (-6.0 to -15.0 diopters; mean deviation [MD], -5.6 ± 5.1 dB) and 91 non-highly myopic eyes (1.0 to -5.5 diopters; MD, -4.9 ± 5.7 dB) were enrolled. In highly myopic eyes (<-6 diopters), the Cohen κ for qualitative decisions by observers was 0.363 for photographs and 0.946 for Spectralis macular scans, and observers' evaluations of Spectralis macular scans were more accurate (94.5% and 94.5%, respectively; P < .0001) than their evaluations of photographs (71.4% and 80.2%, respectively). In the receiver operating characteristic regression analyses assessing the influences of age, sex, MD, and axial length, the better MD (P = .002 to .016) and longer axial length (P = .031 to .041) were associated significantly with diagnostic performances for all or some spectral-domain optical coherence tomography parameters. The receiver operating characteristic curves of average macular ganglion cell complex and circumpapillary RNFL thicknesses were comparable at low MD.

CONCLUSIONS

In high myopes, observers' assessments of the spectral-domain optical coherence tomography macular scans may agree better and be more accurate than observers' optic disc assessments. Glaucoma diagnostic performance of the macular ganglion cell complex may be less affected by axial length compared with that of circumpapillary RNFL.

Myopia and diabetes mellitus as modificatory factors of glaucomatous optic neuropathy

Myopic deformation of the eye and metabolic alterations of the nerve tissue of patients with diabetes may modify glaucomatous optic neuropathy (GON). Blockage of axonal transport of neurotrophic factors (NTFs) is the event crucial to understanding the factors that affect GON. The primary, but not sole, blockage site is at the lamina cribrosa (LC). Other than this primary site of damage at the LC, 7 other factors may explain atypical nerve fiber layer (NFL) defects and the vulnerability of the nerve fibers in eyes with high myopia and glaucoma: a second point of blockage at the edge of the posterior scleral foramen; ectatic strain on the NFL; ectasia and distortion of the LC; association of a hypoplastic optic disc; thin and weak collagen fibers; peripapillary chorioretinal atrophy; and myopic neuropathy. Among diabetic patients, diabetic neuropathy in the retinal NFL is present initially, and increased resistance to aqueous outflow leads to ocular hypertension. Superimposition of GON on diabetic neuropathy and ocular hypertension in patients with diabetes may enhance their susceptibility to nerve damage. Results of a meta-analysis study suggested a positive association between diabetes mellitus and glaucoma whereas other reports suggested that leakage of vascular endothelial growth factor, a survival mechanism of ischemic neural tissue, and enhanced stiffness of the LC as a result of diabetic glycation may protect neurons from apoptosis. Thus, modification of GON as a result of diabetes remains controversial.

Contributing factors for progression of visual field loss in normal-tension glaucoma patients with medical treatment

PURPOSE

To investigate the prognostic factors responsible for the progression of visual field defects (VFDs) in patients with normal-tension glaucoma (NTG) treated with topical antiglaucoma medications.

PATIENTS AND METHODS

A total of 92 eyes in 92 NTG patients treated with only topical antiglaucoma medications for ≥ 5 years were retrospectively analyzed. To identify subfield-based prognostic factors, the central 30-degree visual field (Humphrey Field Analyzer) was divided into 6 subfields: upper and lower arcuate, paracentral, and cecocentral subfields. Factors related to subfield-based progression (age, refraction, mean intraocular pressure (IOP), IOP variability, central corneal thickness, and disc hemorrhage) were evaluated using a linear mixed model.

RESULTS

Ninety-two eyes in 92 NTG patients were included in this study. The mean observation period was 7.7 ± 2.7 (5.0 to 15.5) years, and the estimated rate of change in the mean deviation value was -0.16 ± 0.31 dB/y (P<0.001). A subfield-based linear mixed model analysis of the time course of changes in the mean of total deviation identified a greater extent of myopia as a significant positive prognostic factor for VFD progression in the upper paracentral area (P=0.016). The mean IOP, central corneal thickness, disc hemorrhage, age, and IOP variation showed no significant contribution in any of the subfields.

CONCLUSIONS

The extent of myopia was found to be a significant positive prognostic factor for VFD progression in the upper paracentral subfield for non-high-myopic NTG eyes with an average IOP of 14.2 mm Hg under topical antiglaucoma medication.

Association between myopia and glaucoma in the United States population

PURPOSE

To investigate the association between myopia and the prevalence of glaucoma.

METHODS

This cross-sectional study included 5277 participants from the 2005 to 2008 National Health and Nutrition Examination Survey, greater than or equal to 40 years old, without history of cataract or refractive surgery, who underwent auto-refraction measurement. The predictor was refractive status; emmetropia (-0.99 to +0.99 diopters [D]), mild myopia (-1.00 to -2.99 D), moderate myopia (-3.00 to -5.99 D), severe myopia (> -6.00 D), and hyperopia (> 1.00 D). The outcomes were self-reported glaucoma, vertical cup-to-disc ratio and visual field defects as found on frequency doubling technology (FDT) testing

RESULTS

Odds of self-reported glaucoma were not significantly increased in mild (odds ratio [OR] 0.90, confidence interval [CI] 0.56-1.45), moderate (OR 1.40, CI 0.62-3.16), or severe (OR 0.26, CI 0.08-0.80) myopes compared with emmetropes. Odds of vertical cup-to-disc ratio greater than or equal to 0.7 were not significantly increased in mild (OR 0.84, CI 0.31-2.25), moderate (OR 0.37, CI 0.04-3.57), or severe (OR 0.85, CI 0.09-8.42) myopes compared with emmetropes. Odds of any visual field defects were significantly increased in mild (OR 2.02, CI 1.28-3.19), moderate (OR 3.09, CI 1.42-6.72), and severe (OR 14.43, CI 5.13-40.61) myopes compared with emmetropes. The χ(2) test indicated a significant difference (P = 0.001) in the distribution of subjects with each category of visual field status across subjects with each refractive status; the proportion of subjects with worse visual field defects increased with worsening myopia severity.

CONCLUSIONS

The association between myopia and visual field defects may represent an increased risk of glaucoma among myopes, and the lack of association with self-reported glaucoma may suggest a need for greater glaucoma surveillance in this population.

Association of OPA1 polymorphisms with NTG and HTG: a meta-analysis

BACKGROUND

Genetic polymorphisms of the Optic atrophy 1 gene have been implicated in altering the risk of primary open angle glaucoma (POAG), especially the susceptibility to normal tension glaucoma (NTG), but the results remain controversial.

METHODS

Multiple electronic databases (up to January 20, 2012) were searched independently by two investigators. A meta-analysis was performed on the association between Optic atrophy 1 polymorphisms (rs 166850 and rs 10451941) and normal tension glaucoma (NTG)/high tension glaucoma (HTG). Summary odds ratios (ORs) and 95% confidence intervals (CI) were estimated.

RESULTS

Seven studies of 713 cases and 964 controls for NTG and five studies of 1200 cases and 971 controls for HTG on IVS8+4C>T (rs 166850) and IVS8+32T>C (rs10451941) were identified. There were significant associations between the OPA1 rs10451941polymorphism and NTG susceptibility for all genetic models(C vs. T OR = 1.26, 95% CI 1.09-1.47, p = 0.002; CC vs. TT: OR = 1.52, 95% CI 1.04-2.20, p = 0.029; CC vs. CT+TT: OR = 1.64, 95% CI 1.16-2.33, p = 0.005; CC+CT vs. TT: OR = 1.21, 95% CI 1.02-1.44, p = 0.032). However, no evidence of associations was detected between the OPA1 IVS8+32C>T polymorphism and POAG susceptibility to HTG. Similarly, clear associations between the rs 166850 variant and NTG were observed in allelic and dominant models (T vs. C OR = 1.52, 95% CI 1.16-1.99, p = 0.002; TT+TC vs. CC OR = 1.50, 95% CI 1.13-2.01, p = 0.006) but not to HTG. In subgroup analyses by ethnicity, we detected an association between both OPA1 polymorphisms and risk for NTG in Caucasians but not in Asians. By contrast, no significant findings were noted between OPA1 variants for HTG, either in Caucasians or in Asians.

CONCLUSIONS

Both the IVS8+4C>T and IVS8+32T>C variants may affect individual susceptibility to NTG. Moreover, stratified analyses for NTG detecting the effects of both OPA1 polymorphisms seemed to vary with ethnicity. Further investigations are needed to validate the association.

Risk factors for progression of normal-tension glaucoma under β-blocker monotherapy

PURPOSE

To prospectively study prognostic factors for normal-tension glaucoma (NTG) under treatment with topical β-blocker.

METHODS

One hundred and forty-six eyes of 146 patients with NTG with a mean untreated intraocular pressure (IOP) of 14 mmHg, mild to moderate visual field damage and mean spherical equivalent refraction of -3.5 (-8.0 to +2.0) dioptre were randomized to topical nipradilol or timolol and followed for 3 years. The Humphrey full threshold 30-2 visual field test was performed every 6 months, and optic disc photographs were obtained every 12 months. Progression was defined as visual field progression, optic disc and/or peripapillary nerve fibre layer change, and factors relating to progression were evaluated using Cox proportional hazards models.

RESULTS

IOP decreased by 1.0 mmHg over the 3-year period, during which 35% showed progression according to the aforementioned criteria. Optic disc haemorrhage (hazard ratio [HR] 4.00, p < 0.001) and less extent of myopia (per dioptre, HR 1.15, p = 0.013) were significant risk factors. When progression was defined by visual field progression only, less extent of myopia was again a significant risk factor (HR 1.17, p = 0.038).

CONCLUSION

Beside optic disc haemorrhage, less extent of myopia was a risk factor for progression in the current NTG population where most patients were mildly myopic and IOP during follow-up averaged 13.2 mmHg under topical β-blocker.

Histology of the parapapillary region in high myopia

PURPOSE

To examine histomorphometrically the parapapillary region in highly myopic eyes.

DESIGN

Retrospective laboratory investigation.

METHODS

We examined a highly myopic glaucomatous group (36 human globes; axial length >26.5 mm) and a non-highly myopic group (28 globes with secondary angle-closure glaucoma; 17 eyes with malignant choroidal melanoma). Using light microscopy, pupil-optic nerve sections were assessed.

RESULTS

The length of the scleral flange (sclera between optic nerve border and optic nerve dura mater) increased with axial length (P < .001; correlation coefficient r = 0.70) and decreased with its thickness (P < .001; r = 0.75). In all highly myopic eyes (n = 15) with a distance of >0.5 mm between optic nerve border and beginning of Bruch membrane, the parapapillary region consisted of an elongated parapapillary scleral flange associated with a scleral flange thinning and a retrobulbar cerebrospinal fluid space extended into the retroparapapillary region. The parapapillary retina was composed of retinal nerve fiber layer (or its remnants) only, without elements of any other retinal layer, without underlying Bruch membrane or choroid. These histologic features were not detected in any of the non-highly myopic eyes.

CONCLUSIONS

Since parapapillary scleral thickness influences the lamina cribrosa biomechanics, the findings may partially explain the increased glaucoma susceptibility in highly myopic eyes. The implications of an absence of Bruch membrane and choroid in the highly myopic parapapillary region, and the implications of the retrobulbar parapapillary extension of the cerebrospinal spinal fluid space for the pathophysiology of the optic nerve head, have to be elucidated.

Comparison of newly diagnosed ocular hypertension and open-angle glaucoma: ocular variables, risk factors, and disease severity

Purpose. To describe the distribution of ocular variables, risk factors, and disease severity in newly diagnosed ocular hypertension (OH) or open-angle glaucoma (OAG). Methods. Eligible subjects underwent a complete history and examination. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) obtained from multiple logistic regression models were used to compare OAG to OH and advanced to early/moderate OAG. Results. 405 subjects were enrolled: 292 (72.1%) with OAG and 113 (27.9%) with OH. 51.7% had early, 27.1% moderate, and 20.9% advanced OAG. The OR for OAG versus OH was 8.19 (P < 0.0001) for disc notch, 5.36 (P < 0.0001) for abnormal visual field, 1.45 (P = 0.001) for worsening mean deviation, 1.91 (P < 0.0001) for increased cupping, 1.03 for increased age (P = 0.030), and 0.36 (P = 0.010) for smoking. Conclusions. Increased age was a risk for OAG, and smoking decreased the risk of OAG compared to OH. Almost half of the OAG subjects had moderate/advanced disease at diagnosis.

The bugeye mutant zebrafish exhibits visual deficits that arise with the onset of an enlarged eye phenotype

PURPOSE

The bugeye mutant has an enlarged eye phenotype, presumably because of elevated intraocular pressure. Since elevated intraocular pressure is a significant risk factor for glaucoma, the bugeye zebrafish mutant may be a model organism for the disease.

METHODS

The optomotor response (OMR) was used to assess visual responsiveness in both larval and adult zebrafish. Electroretinograms (ERGs) were recorded to measure outer retinal function, and histologic analyses were performed on WT and mutant eyes.

RESULTS

At 5 days old, bugeye mutants have an OMR, ERGs, and retinal morphology indistinguishable from those of wild-type (WT) animals. By 2 months of age, bugeye mutants begin to develop an enlarged eye phenotype. At 3 months, some mutants show deficits in the OMR assay, including lower contrast sensitivity. The data suggest that there is a correlation between the size of the enlarged eye and the degree of OMR deficit. Histologic analysis of the bugeye mutant retina revealed decreases in retinal ganglion cell densities by 3 months. By 5 months, the mutant's ERG b-wave had smaller amplitudes and longer latencies at brighter light intensities than those of the WT fish.

CONCLUSION

After phenotypic onset at 3 months, the bugeye mutants begin to develop visual deficits. At 3 months, bugeye mutants exhibit a decrease in retinal cell densities and by 5 months, they show diminished outer retinal function. In summary, the bugeye mutant provides a means of studying glaucoma-associated phenotypes in the zebrafish.

[Is myopia a risk factor for glaucoma?]

Controversy exists in the literature concerning the role of axial myopia as a risk factor for primary open-angle glaucoma. Epidemiologic evidence suggests that moderate and especially high myopia with a refractive error exceeding -6D is a risk factor for the development and the progression of glaucomatous optic neuropathy, with a twofold to threefold increased risk of glaucoma compared with that of nonmyopic subjects. This risk has been proven to be independent of other glaucoma risk factors and intraocular pressure (IOP). Myopic eyes have slightly although probably not clinically relevant, higher IOPs than emmetropic or hyperopic eyes. Selection bias could account for some of the reported association between glaucoma and myopia given that myopic subjects are likely to consult their ophthalmologist more frequently and glaucoma is underdiagnosed in myopic patients due to the great variability of their optic disc morphology, especially in high myopia, and the difficulty to interpret their visual field. The weakness of the fibroglial matrix of the nerve fibers at the optic disc together with the structural alterations in the lamina cribrosa and choroid, could contribute to the high susceptibility of the optic disc to IOP fluctuations and to increasing the risk of glaucomatous neuropathy, especially in high myopic eyes. Special attention will be given to patients with mild myopia who present with both elevated IOP levels and a positive family history. On the other hand, high myopic subjects should be screened for glaucoma at closer intervals. Moreover, after appropriate adjustments for deviations in central corneal thickness have been made, IOP greater than 17 mmHg must already be regarded as critical and initiation of medical treatment considered.

Methodologic quality of studies on prognostic factors for primary open-angle glaucoma progression measured by visual field deterioration

Glaucoma is a chronic, slowly progressing, and asymptomatic optic neuropathic disorder with a great variety of causes that involve gradual retinal ganglion cell axon loss. The disease is the second most common cause of blindness in the industrialized world. Once vision loss develops it is irreversible-although in many cases further loss can be slowed if adequate treatment is provided. If not treated, glaucoma can lead to complete vision loss in the affected eye. Primary open-angle glaucoma (POAG) is the most prevalent form of the disease in the industrialized countries, representing 94% of all glaucomas. In a Spanish study of 569 individuals, the prevalence of POAG was 2.1% (99% confidence interval 1.9%-2.3%) in the age range between 40 and 79 years. Assessing glaucomatous damage progression remains one of the most important and challenging aspects in glaucoma management. In addition, a better understanding of clinical risk factors for glaucoma worsening may help us to develop new strategies to improve glaucoma care. Over the past 2 decades, many studies have addressed the issue of risk factors associated with or predicting for glaucoma progression. Although many studies have attempted to identify the prognostic factors capable of predicting the course of POAG, the results have been varied and in some cases contradictory, and are thus of scant practical utility. This study was designed to evaluate the methodologic quality of the studies published in the literature on the prognostic factors for POAG progression measured by visual field deterioration.

Preparation and evaluation of a contact lens vehicle for puerarin delivery

The purpose of this study is to develop a soft contact lens vehicle for puerarin delivery to alleviate glaucoma. Poly(2-hydroxy-ethyl methacrylate-co-N-vinylpyrrolidone-co-methyl acrylate) (pHEMA-NVP-MA) contact lenses were prepared by UV irradiation of HEMA, NVP and MA, to which the cross-linker, a mixture of trimethylolpropane trimethacrylate (TMPTMA) and allyl methacrylate (AMA) (1:1, w/w) was added previously. The contact lenses were characterized by equilibrium swelling ratio (ESR) and tensile tester. The results showed that incorporation of poly-N-vinylpyrrolidone (PVP) component in the hydrogels caused increase of ESR and decrease of tensile strength. Co-polymerization of MA monomer in the hydrogel led to a slight drop of ESR and improved tensile strength of hydrogel. Four kinds of hydrated contact lenses with different PVP content were presoaked in PBS solution of puerarin and the in vitro drug release was measured. The contact lenses matrix incorporated with PVP had a remarkable loading capacity of puerarin. In rabbit eyes, the presoaked contact lenses extended the mean resident time of puerarin to 77.45 min from 12.88 min of 1% puerarin eye drops. Moreover, contact lens presoaked in puerarin solution at the concentration of 0.802 mg/ml showed about the same bioavailability (AUC(0-t)) in tear fluid as that of the puerarin eye drops. This kind of presoaked contact lens has potential application as vehicle of puerarin to alleviate glaucoma.

Influence of the extent of myopia on the progression of normal-tension glaucoma

PURPOSE

To evaluate the influence of the extent of myopia on the progression rate of normal-tension glaucoma (NTG).

DESIGN

Retrospective, observational case series.

METHODS

One hundred forty-three eyes of 143 patients with NTG who were treated from 1994 through 2006 and followed up with standard automated perimetry were evaluated in this study. The participants were divided into 4 groups: mild myopia (-0.76 to -2.99 diopters [D]), moderate myopia (-3 to -5.99 D), severe myopia (-6 D or less), and nonmyopia (emmetropia and hyperopia, -0.75 D or more) groups. The change in mean deviation, corrected pattern standard deviation, mean thresholds of 10 zones corresponding to the glaucoma hemifield test, and thresholds of 52 points of the nonmyopia group were compared with those of the other myopia groups. Additionally, we controlled each analysis for age and posttherapeutic intraocular pressure to preclude the possibility of these covariates influencing the analysis of the effect of myopia on the progression of glaucoma.

RESULTS

There was no statistically significant difference between the nonmyopia group and each of the myopia groups in terms of mean deviation, corrected pattern standard deviation, mean thresholds of 10 zones corresponding to the glaucoma hemifield test, and the thresholds of 52 point changes against refraction. Moreover, with the control of the other covariates (age and posttherapeutic intraocular pressure), no statistically significant differences were noted (multivariate analysis using mixed model, P > .1).

CONCLUSIONS

Although a high incidence of open-angle glaucoma among myopic patients has been reported previously, myopia did not influence the progression rate of NTG after treatment.

Association between high myopia and progression of visual field loss in primary open-angle glaucoma

BACKGROUND/PURPOSE

Taiwan has a very high prevalence rate of myopia. We retrospectively studied the influence of myopia on the progression of visual field (VF) loss in primary open-angle glaucoma (POAG) patients.

METHODS

We studied 515 POAG patients for a minimum follow-up period of 5 years. VF examination was performed with Humphrey perimeter, 30-2 SITA standard program, every 6 months. A point-wise numerical comparison was applied to judge the VF changes. Test points showing more than 1.0 dB of sensitivity loss in mean defect were identified. A location was considered to have progression if it was detected on two consecutive visits. Progression of VF loss was confirmed if three or more test points deteriorated. Multivariate logistic regression was used to evaluate the association between progression of VF loss and various risk factors.

RESULTS

There were 262 cases. Progression of VF loss occurred in 57 eyes (21.8%) during the 5-year follow-up period. Logistic regression revealed that the deterioration was associated with older age, higher mean intraocular pressure, larger vertical cup-to-disc ratio, and greater myopic refraction status. The incidence of VF loss progression was 15.1% in the group of eyes with myopia less than -3 D, 10.5% in the group with -3 D to -6 D, 34.4% in the group with -6 D to -9 D, and 38.9% in the group with myopia greater than -9 D.

CONCLUSION

POAG patients with myopia greater than -6 D had a greater progression of VF loss.

Ocular hypertension and diabetes mellitus in the Beijing Eye Study

PURPOSE

To determine prevalence and associated factors of ocular hypertension in the adult Chinese population.

METHODS

The Beijing Eye Study, a population-based prevalence study, included 4439 subjects out of 5324 subjects with an age of 40+ years invited to participate (response rate 83.4%). From the 4439 individuals, 4224 (95.2%) subjects fulfilled the inclusion criteria of the present study, that is, available readable optic disc photographs, a nonglaucomatous appearance of the optic disc, and a normal visual field in the case of an intraocular pressure higher than 21 mm Hg. The participants underwent an interview, a detailed ophthalmic examination, blood pressure measurements, and examination of blood samples. Ocular hypertension was defined as an intraocular pressure higher than 21 mm Hg with a normal appearance of the optic nerve head and no defects in frequency doubling perimetry.

RESULTS

Ocular hypertension was detected in 299 (3.6%) eyes (prevalence rate: 3.63%+/-0.21%) of 160 (3.8%) subjects (prevalence rate: 3.79%+/-0.29%). In multiple regression analysis, ocular hypertension was significantly associated with serum levels of cholesterol [P=0.006; odds ratio (OR): 1.34; 95% confidence interval (CI): 1.09-1.64], presence of diabetes mellitus (P=0.03; OR: 1.45; 95% CI: 1.04-2.07) and arterial hypertension (P<0.001; OR: 3.18; 95% CI: 1.86-5.43). Ocular hypertension was not significantly associated with age, sex, urban or rural region, refractive error, anterior chamber depth, optic disc area, and area of beta zone of parapapillary atrophy.

CONCLUSIONS

Ocular hypertension has a frequency of about 3.6% in the adult Chinese population with an age of 40+ years. Associated factors are diabetes mellitus, arterial hypertension, and elevated serum cholesterol levels. Diabetes mellitus, arterial hypertension, and elevated serum cholesterol concentrations should be checked in ocular hypertensive subjects.

Long axial length as risk factor for normal tension glaucoma

BACKGROUND

The high prevalence of normal tension glaucoma (NTG) in the Japanese requires special screening tests other than measurements of only the intraocular pressure (IOP). This study was carried out to determine whether there is a significant association between the axial length of the eye and the presence of NTG.

METHODS

We reviewed the medical records of all patients who were scheduled to undergo cataract surgery alone or combined with glaucoma surgery at the same time. There were 87 patients with NTG, 137 with POAG, and 978 non-glaucomatous control cases. The axial length, IOP, curvature of the anterior corneal surface, age, and gender were determined at the time of the operation. If both eyes had surgery, data from only the right eyes were analyzed. An association of these parameters with NTG and POAG was analyzed by logistic regression analysis. The three groups were analyzed for differences in the axial length using the Kruskal-Wallis test followed by the Mann-Whitney U test.

RESULTS

The axial length was significantly associated with NTG (odds = 1.24, P = 0.002) and POAG (odds = 1.28, P = 0.001). The incidence of either POAG or NTG was significantly higher in patients with axial lengths >or=25.0 mm (odds = 2.29, P < 0.001, Fisher's exact test). The age at the time of cataract surgery was weakly but significantly correlated negatively with the axial length (r = -0.24, P < 0.001, Pearson's correlation coefficient test). Men had significantly longer axial lengths than women.

CONCLUSIONS

Long axial lengths can be considered a risk factor for NTG and POAG, and patients with long axial lengths need to be carefully examined for glaucoma.

Effect of statin drugs and aspirin on progression in open-angle glaucoma suspects using confocal scanning laser ophthalmoscopy

PURPOSE

To determine the effect of statins and aspirin on the rate of progression of optic nerve parameters in open-angle glaucoma (OAG) suspects, as defined by confocal scanning laser ophthalmoscopy (CSLO).

METHODS

Data of OAG suspects who had undergone at least two CSLO tests at the Beckman Vision Center at UCSF from January 2001 to June 2006 was collected. We conducted a retrospective chart review of 149 eyes from 76 patients considered suspect for glaucoma based on a cup-to-disc ratio >0.5, but with normal intraocular pressures (IOP) and visual fields. Subjects included glaucoma suspects who took statin drugs or aspirin for greater than 23 months. The control group consisted of suspects who never used statins or aspirin. The data were analysed using mixed effects regression.

RESULTS

When comparing controls with the statin group there were significant differences in the progression of multiple CSLO parameters per year, including rim volume (-13.7% controls, +26.7% statin only; P = 0.0156), retinal nerve fibre layer cross-sectional area (-12.2% controls, +24.3% statin only; P = 0.0051), and mean global retinal nerve fibre layer thickness (-10.3% controls, +26.6% statin only; P = 0.0114), with adjustment for age, gender, race, IOP, central corneal thickness, refractive error and multiple systemic comorbidities. No significant differences were found when comparing subjects taking a statin plus aspirin or aspirin alone with the controls.

CONCLUSIONS

Statin drugs may be associated with slowed progression of optic nerve parameters in glaucoma suspects as measured by CSLO.

[Myopia and glaucoma]

The question is whether there is an increased risk to develop glaucoma in co-existing myopia. The different kinds of glaucoma dealing with this problem are described. The highly myopic eye with increased axial length shows many structural changes. Especially the changes of the optic nerve head in a highly myopic eye make it very difficult to differentiate between a beginning glaucoma and a normal structure or to define a progression of glaucomatous changes. The visual field defects are often close to fixation and may reduce visual acuity and therefore the quality of life of these usually younger patients. An increase of the thickness of the lens induced by senile cataract, drugs or diabetes mellitus, a forward shift of the lens or the iris-lens-diaphragm will lead to refractive myopia and may provoke an angle closure glaucoma. Pigmentary glaucoma occurs in younger patients in connection with low or medium myopia and more rapidly destroys the optic nerve head due to higher intraocular pressure values in comparison to the primary open-angle glaucoma. After refractive surgeries of myopic eyes one has to expect different kinds of glaucoma (steroid induced, pupillary block, angle closure). Due to the increased risk to develop glaucoma patients especially with high myopia are advised to consult their ophthalmologist on a regular basis.

The influence of low to moderate myopia on retinal nerve fiber layer as assessed by scanning laser polarimetry with variable corneal compensator

PURPOSE

To evaluate the influence of different degrees of myopia on retinal nerve fiber layer (RNFL) as measured by scanning laser polarimetry (SLP) with variable corneal compensator (VCC) in healthy eyes.

METHODS

One hundred and seventy-four healthy age-matched subjects with low to high myopic and emmetropic eyes underwent RNFL measurement by means of GDxVCC. The GDx parameters included in the analysis were: Temporal-superior-nasal-inferior thickness (TSNIT) average, Superior average, Inferior average, TSNIT standard deviation, Inter-eye symmetry, NFI, Symmetry, Superior ratio, Inferior ratio, Superior/nasal, Maximum modulation, Superior maximum, Inferior maximum, Ellipse modulation, Normalized superior area, Normalized inferior area, Ellipse standard deviation, Ellipse average. The mean value of each SLP parameter of myopic eyes was compared with the mean value of the same parameter of emmetropic eyes.

RESULTS

Mean myopia was 3.9 +/- 1.5 dpt (range: -2 to -8.25 dpt). TNSIT average was higher in myopic group (p = 0.0111), together with Superior average (p = 0.0244), Symmetry (p < 0.0001) and Ellipse average (p = 0.0111). Two ratio parameters, Superior ratio and Inferior ratio, were higher in emmetropic eyes (p = 0.0179 in both cases). In both the myopic and the emmetropic group, all the SLP assessments of the RNFL fell within the normal range, according to the GDx database.

CONCLUSIONS

Low to high myopia is not related to clinically relevant variations of SLP parameters, as assessed with GDx-VCC.

Vascular risk factors in glaucoma: the results of a national survey

BACKGROUND

The role of vascular risk factors in glaucoma is still being debated. To assess the importance of vascular risk factors in patients with primary open-angle glaucoma (POAG), data from the medical history of 2,879 POAG patients and 973 age-matched controls were collected and analyzed.

METHODS

DESIGN

observational survey.

SETTING

35 Italian academic centers.

STUDY POPULATION

POAG patients and age-matched controls. In order to reduce bias consecutive patients were included.

OBSERVATION PROCEDURES

data concerning vascular risk factors were collected for all patients with a detailed questionnaire. A complete ophthalmological examination with assessment of intraocular pressure (IOP), visual field, optic disc, and systemic blood pressure was performed.

MAIN OUTCOME MEASURES

the ESH-ESC (European Society of Hypertension-European Society of Cardiology) guidelines were used to calculate the level of cardiovascular risk. Crude and adjusted estimates of the odds ratios (OR) were calculated for all cardiovascular risk factors in POAG and controls.

RESULTS

The study included 2,879 POAG patients and 973 controls. POAG cases had a significantly higher systolic and diastolic blood pressure (p = 0.001) and systolic perfusion pressure (p = 0.02) as compared with controls. Also mean IOP was significantly higher in the POAG group (p = 0.01), while diastolic perfusion pressure was not significantly different in the two groups. Myopia was more prevalent in the POAG group (23 vs 18%, p = 0.005) as well as a positive family history for glaucoma (26 vs 12%, p = 0.004). POAG patients tended to have a higher cardiovascular risk than controls: 63% of glaucoma cases vs 55% of controls (OR: 1.38, p = 0.005) had a "high" or "very high" cardiovascular risk.

CONCLUSIONS

The level of cardiovascular risk was significantly higher in glaucoma patients than in controls.