Clinical Profiles of Primary Open Angle Glaucoma versus Normal Tension Glaucoma Patients: A Pilot Study

Multiple Systemic Vascular Risk Factors Are Associated With Low-Tension Glaucoma

PRCIS

Multiple systemic vascular-associated conditions including systemic hypertension and hypotension, diabetes mellitus, migraine headache, peripheral vascular disease, Raynaud syndrome, and anemia were associated with low-tension glaucoma.

PURPOSE

The purpose of this study was to identify systemic risk factors associated with low-tension glaucoma.

PATIENTS AND METHODS

A retrospective case-control study design was employed to identify patients seen at the Mayo Clinic Department of Ophthalmology between 2005 and 2015 with low-tension glaucoma and an age-matched and sex-matched control group, each containing 277 patients.

RESULTS

The low-tension glaucoma group had more myopic refractive errors (-1.6 vs. -1.0 D, P<0.001), lower intraocular pressure (14.2 vs. 15.2 mm Hg, P<0.001), and a higher cup-to-disc ratio (0.7 vs. 0.3, P<0.001). The low-tension glaucoma group was significantly less likely to be obese (body mass index >30, P=0.03). This group had a significantly higher prevalence of systemic hypertension [odds ratio (OR): 1.64, P=0.004], diabetes mellitus (OR: 3.01, P<0.001), peripheral vascular disease (OR: 2.61, P=0.009), migraine headache (OR: 2.12, P=0.02), anemia (OR: 2.18, P=0.003), systemic hypotension (OR: 4.43, P<0.001), Raynaud syndrome (OR: 3.09, P=0.05), and angiotensin-converting enzyme inhibitor (OR: 1.64, P=0.01) or calcium channel blocker use (OR: 1.98, P=0.004). After adjusting for systemic hypertension, calcium channel blocker use remained significant (OR: 1.70, P=0.03). No significant difference was found between groups with respect to hyperlipidemia, obstructive sleep apnea, coronary artery disease, carotid stenosis, stroke, or statin, angiotensin-converting enzyme inhibitor, angiotensin receptor blocker, beta-blocker, or metformin use.

CONCLUSIONS

Multiple vascular-associated conditions were associated with low-tension glaucoma including systemic hypertension, diabetes mellitus, peripheral vascular disease, migraine headache, Raynaud syndrome, anemia, systemic hypotension, and calcium channel blocker use. This study strengthens the evidence for the vascular hypothesis of low-tension glaucoma.

Comparisons of ganglion cell-inner plexiform layer loss patterns and its diagnostic performance between normal tension glaucoma and primary open angle glaucoma: a detailed, severity-based study

AIM

To evaluate the patterns of macular ganglion cell-inner plexiform layer (GCIPL) loss in normal tension glaucoma (NTG) and primary open angle glaucoma (POAG) in a detailed, disease severity-matched way; and to assess the diagnostic capabilities of GCIPL thickness parameters in discriminating NTG or POAG from normal subjects.

METHODS

A total of 157 eyes of 157 subjects, including 57 normal eyes, 51 eyes with POAG and 49 eyes with NTG were enrolled and strictly matched in age, refraction, and disease severity between POAG and NTG groups. The average, minimum, superotemporal, superior, superonasal, inferonasal, inferior, and inferotemporal GCIPL thickness, and the average, superior, temporal, inferior, and nasal retinal nerve fiber layer (RNFL) thickness were obtained by Cirrus optical coherence tomography (OCT). The diagnostic capabilities of OCT parameters were assessed by area under receiver operating characteristic (AUROC) curves.

RESULTS

Among all the OCT thickness parameters, no statistical significant difference between NTG group and POAG group was found (all P>0.05). In discriminating NTG or POAG from normal subjects, the average and inferior RNFL thickness, and the minimum GCIPL thickness had better diagnostic capabilities. There was no significant difference in AUROC curve between the best GCIPL thickness parameter (minimum GCIPL) and the best RNFL thickness parameter in discriminating NTG (inferior RNFL; P=0.076) and indiscriminating POAG (average RNFL; P=0.913) from normal eyes.

CONCLUSION

Localized GCIPL loss, especially in the inferior and inferotemporal sectors, is more common in NTG than in POAG. Among all the GCIPL thickness parameters, the minimum GCIPL thickness has the best diagnostic performance in differentiating NTG or POAG from normal subjects, which is comparable to that of the average and inferior RNFL thickness.

Disc haemorrhages in Polish Caucasian patients with normal tension glaucoma

AIM

The aim of this observational study was to evaluate the epidemiology of disc haemorrhages (DH) in Polish patients with normal tension glaucoma (NTG) and their association with some risk factors.

MATERIAL AND METHODS

The group studied consisted of 274 Caucasian patients with NTG (410 eyes) divided into those with disk haemorrhages (DH+, = 94 eyes in 81 patients) and those without disc haemorrhages (DH-, = 316 eyes in 193 patients). Ophthalmic examinations with visual field (VF) testing were carried out in these patients every 3 months for at least 18 months. The medical history was recorded taking glaucoma, other ophthalmic diseases, chronic general disorders and vascular risk factors into account.

RESULTS

Unilateral and bilateral DH were observed more frequently in women (p = 0.0010). Maximum IOP was significantly higher in the DH+ group (p = 0.000026). Notches and peripapillary atrophy were found with similar frequency in DH+ and DH- patients (p = 0.4631). The mean defect (MD) in the VF at the time of diagnosis was lower in the DH+ group (-6.27 dB) than in the DH group (-10.14 dB), (p = 0.000055). The initial MD in the DH+ group had a positive correlation with maximum initial IOP. A progressive loss of VF was observed in 206 eyes with NTG (50.2%), with a mean of 0.72 dB/year. The progression was more frequent in DH+ patients (78.4% versus 41.1%), but there were no statistically significant differences in the rate of progression between DH+ and DH- patients (p = 0.46). The morphology of early scotoma depended on the presence of DH (p < 0.00001), and early scotoma in the DH+ group was more frequently localized paracentrally. There was a significant difference in a number of antiglaucoma drops between DH+ and DH- patients (p < 0.00001). There were no differences in the frequency of migraines between both groups (p = 0.31). General hypotension was observed with similar frequency in the DH+ DH- groups (p = 0.3). General hypertension was less frequent in DH+ patients (p = 0.041), especially in women (p = 0.000027). Diabetes mellitus (DM) was significantly less frequent (21.3%) in patients with DH+ (3.7%) than in the DH- group (p = 0.000852), especially among the women (p = 0.000216).

CONCLUSION

In our study, DH were more frequent both unilaterally and bilaterally in women. Initial intraocular pressure (IOP) was higher in NTG patients with DH, and early scotoma was localized in the paracentral area of the VF. Disc haemorrhages (DH) were less frequent in women with general hypertension and with diabetes mellitus.

Is normal-tension glaucoma a risk factor for stroke?-A 10-year follow-up study

OBJECTIVES

To investigate whether patients with normal-tension glaucoma (NTG) have a higher incidence of stroke.

DESIGN

A population-based retrospective cohort study based on data from the Taiwan National Health Insurance Research Database (NHIRD) from January 1, 2001, to December 31, 2010.

METHODS

Data were retrospectively collected from the NHIRD. A total of 245 (20.1%) patients with a history of stroke at the time of glaucoma diagnosis were excluded, and 1,218 patients with NTG who were 20 years of age and older were identified. Patients' age, gender and pre-existing comorbidities, including hypertension, diabetes, congestive heart failure, ischemic heart disease, atrial fibrillation and disorders of lipid metabolism, were recorded. The propensity score method with a 1:5 matching ratio was used to minimize selection bias. Cox regression with robust variance estimation was used to estimate the hazard ratio (HR) of developing stroke between the NTG and control groups.

RESULTS

After adjusting for patient age, gender, and pre-existing comorbidities, the HR was 6.34, indicating that the incidence of stroke was significantly higher in patients with NTG than in controls. Furthermore, a higher risk of stroke was also found in most subgroups with the above-mentioned comorbidities.

CONCLUSION

NTG is a significant risk factor for subsequent stroke in most of the described comorbidity subgroups. Early interventions for stroke prevention should be provided to newly diagnosed patients with NTG.

Undetected angle closure in patients with a diagnosis of open-angle glaucoma

OBJECTIVE

The aim of this study was to identify the proportion of patients referred to a tertiary glaucoma centre with a diagnosis of open-angle glaucoma (OAG) who were found to have angle closure glaucoma.

DESIGN

Retrospective chart review.

METHODS

Consecutive new patients referred for glaucoma management to a tertiary centre between July 2010 and December 2011 were reviewed. Patients whose referrals for glaucoma assessment specified angle status as "open" were included. The data collected included glaucoma specialist's angle assessment, diagnosis, and glaucoma severity. The status of those with 180 degrees or more Shaffer angle grading of 0 was classified as "closed."

RESULTS

From 1234 glaucoma referrals, 179 cases were specified to have a diagnosis of OAG or when angles were known to be open. Of these, 16 (8.9%) were found on examination by the glaucoma specialist to have angle closure. Pseudoexfoliation was present in 4 of 16 patients (25%) in the missed angle-closure glaucoma (ACG) group and 22 of 108 patients (13.5%) in the remaining OAG group. There was no difference found in demographic or ocular biometric parameters between those with confirmed OAG versus those with missed ACG.

CONCLUSIONS

Almost 1 in 11 patients referred by ophthalmologists to a tertiary glaucoma centre with a diagnosis of OAG were in fact found to have angle closure. Given the different treatment approaches for ACG versus OAG, this study suggests a need to strengthen angle evaluations.

New directions in the treatment of normal tension glaucoma

Glaucoma is a progressive optic neuropathy that causes characteristic changes of the optic nerve and visual field in relation to intraocular pressure (IOP). It is now known that glaucoma can occur at statistically normal IOPs and prevalence studies have shown that normal tension glaucoma (NTG) is more common than previously thought. While IOP is believed to be the predominant risk factor in primary open angle glaucoma (POAG), IOP-independent risk factors, such as vascular dysregulation, are believed to play an important part in the pathogenesis of NTG. Though certain distinguishing phenotypic features of NTG have been reported, such as an increased frequency of disc hemorrhages, acquired pits of the optic nerve and characteristic patterns of disc cupping and visual field loss, there is much overlap of the clinical findings in NTG with POAG, suggesting that NTG is likely part of a continuum of open angle glaucomas. However, IOP modification is still the mainstay of treatment in NTG. As in traditional POAG, reduction of IOP can be achieved with the use of medications, laser trabeculoplasty or surgery. Studies now show that the choice of medication may also be important in determining the outcomes of these patients. Though it is likely that future treatment of NTG will involve modification of both IOP and IOP-independent risk factors, current efforts to develop IOP-independent neuroprotective treatments have not yet proven to be effective in humans.

Macular inner plexiform and retinal nerve fiber layer thickness in glaucoma

PURPOSE

To compare the parameters of the macular ganglion cell-inner plexiform layer (mGCIPL) thickness measured by Cirrus high-definition optical coherence tomography in normal-tension glaucoma (NTG) and primary open-angle glaucoma (POAG).

METHODS

Eighty patients with NTG, 80 patients with POAG, and 100 normal control subjects were enrolled. The mGCIPL and peripapillary retinal nerve fiber layer (pRNFL) thicknesses measured by Cirrus high-definition optical coherence tomography were compared in patients with glaucoma. The areas under the receiver operating characteristic curve (AROCs) were calculated to compare the diagnostic power of the mGCIPL thickness with that of the pRNFL thickness. Pearson correlation coefficients were determined to investigate the correlation between the mGCIPL or pRNFL thickness parameters and the mean deviation (MD) values of visual field tests.

RESULTS

All parameters of the mGCIPL thickness were significantly different between normal control subjects and patients with glaucoma. The superior, superotemporal, and superonasal thickness of mGCIPL and the superior thickness of pRNFL showed significant reductions and significantly higher AROCs for distinguishing between normal eyes and eyes with glaucoma in POAG compared with those in NTG. In NTG or POAG groups, the mGCIPL and pRNFL parameters with the highest AROC were the minimum and average thickness, respectively. The average, minimum, inferior, inferotemporal, and inferonasal thickness of mGCIPL and the average and inferior thickness of pRNFL were correlated with MD in NTG (p < 0.05 for all parameters), whereas all parameters of the mGCIPL thickness except the inferonasal thickness and all parameters of the pRNFL thickness except the temporal thickness were correlated with MD in POAG (p < 0.05 for all parameters).

CONCLUSIONS

The diagnostic ability of the mGCIPL thickness was comparable to that of the pRNFL thickness in patients with NTG or POAG. The mGCIPL loss in NTG was localized and mainly concentrated on the inferior portion compared with diffuse mGCIPL loss in POAG.

Metabolic syndrome: a risk factor for high intraocular pressure in the Israeli population

AIM

To evaluate the association among elevated intraocular pressure (IOP), the metabolic syndrome (MetS), body mass index (BMI), and some of their components in the Israeli population.

METHODS

We retrospectively reviewed the charts of 12 747 soldiers of the Israeli Defense Forces, aged 35y or older, who underwent a routine periodical medical examination between 1991 and 2004. None of the subjects received medical treatment for either glaucoma or ocular hypertension. High IOP (>21 mm Hg) was correlated with age, sex, arterial blood pressure, total blood cholesterol levels, triglyceride levels, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, smoking, BMI and MetS.

RESULTS

A statistically significant difference was found between the IOP of subjects with a low risk and higher risk for the development of MetS (P<0.0001 for males, P=0.0026 for females). A statistically significant positive correlation was found in male subjects between high BMI and elevated IOP (r=0.11677, P<0.0001).

CONCLUSION

MetS and BMI were significantly more prevalent in subjects with increased IOP levels. We suggest that both should be taken into consideration in the assessment of glaucoma suspects.

Vascular comorbidity in patients with low-tension glaucoma

PURPOSE

To report vascular comorbidities, arterial hypertension (HT), ischemic heart disease (IHD), and diabetes mellitus (DM) in patients with low-tension glaucoma (LTG) with maximum intraocular pressure (IOP) of 18 mm Hg or less. Uniform criteria for glaucoma and the comorbidities were applied.

METHODS

We reviewed records of 519 consecutive patients to whom the Finnish National Social Insurance Institution (FSII) had granted cost-free medication for the treatment of glaucoma. The FSII operates national health insurance, which is compulsory for all Finnish citizens. There were 344 patients with primary open-angle glaucoma (POAG) and 155 with exfoliative glaucoma (EG). Twenty cases were discarded for having other types of glaucoma. In the POAG group, there were 38 patients, with a median IOP of 16 mm Hg (range 12-18). We were masked to the systemic comorbidities when the registry provided us data on those to whom FSII had also granted cost-free medication for HT, IHD, or DM according to the uniform national criteria.

RESULTS

None of the patients with LTG had exfoliation syndrome. There was a female predominance, 81%, compared to 68% in high-tension POAG. Hypertension had been diagnosed in 34%, which is the same as in high-tension POAG. A total of 24% had IHD, which is the same as in the Finnish population registry. Diabetes mellitus was present in only 5%. In all groups, patients with LTG with systemic comorbidity were markedly older than those without.

CONCLUSIONS

In patients with LTG with median IOP 16 mm Hg (range 12-18), glaucomatous optic disc cupping and glaucomatous visual field defects probably developed independently of the systemic vascular comorbidity. However, the diagnostic criteria for HT, IHD, and DM used in the current study were based on the severity of stages set in the FSII system.

The role of cerebrospinal fluid pressure in glaucoma and other ophthalmic diseases: A review

Glaucoma is one of the most common causes of blindness in the world. Well-known risk factors include age, race, a positive family history and elevated intraocular pressures. A newly proposed risk factor is decreased cerebrospinal fluid pressure (CSFP). This concept is based on the notion that a pressure differential exists across the lamina cribrosa, which separates the intraocular space from the subarachnoid fluid space. In this construct, an increased translaminar pressure difference will occur with a relative increase in elevated intraocular pressure or a reduction in CSFP. This net change in pressure is proposed to act on the tissues within the optic nerve head, potentially contributing to glaucomatous optic neuropathy. Similarly, patients with ocular hypertension who have elevated CSFPs, would enjoy a relatively protective effect from glaucomatous damage. This review will focus on the current literature pertaining to the role of CSFP in glaucoma. Additionally, the authors examine the relationship between glaucoma and other known CSFP-related ophthalmic disorders.

Body mass index has a linear relationship with cerebrospinal fluid pressure

PURPOSE

To examine the relationship between body mass index (BMI) and cerebrospinal fluid pressure (CSFP), as low BMI and low CSFP have recently been described as risk factors for primary open-angle glaucoma (POAG).

METHODS

This was a retrospective review of the electronic medical records of patients who had CSFP measured by lumbar puncture and data to calculate BMI at the Mayo Clinic (Rochester, MN). Exclusion criteria included diagnoses, surgical procedures and medications known to affect CSFP. Mean CSFP for each unit BMI was calculated. The probabilities were two-tailed, and the α level was set at P < 0.05. Patients with documented BMI, CSFP, and intraocular pressure (IOP) were analyzed for the relationship between IOP and BMI.

RESULTS

A total of 4235 patients, primarily of Caucasian descent, met the entry criteria. Median BMI was 26 and the mean CSFP was 10.9 ± 2.6 mm Hg. The increase in CSFP with increasing BMI was linear with an r(2) = 0.20 (P < 0.001). CSFP increased by 37.7% from BMI 18 (8.6 ± 2.1 mm Hg) to BMI 39 (14.1 ± 2.5 mm Hg). The r(2) (0.21) of the model of BMI and sex was similar to the r(2) of a BMI-only model (0.20). There was no relation between IOP and BMI within a subgroup of the study population (r (2) = 0.005; P = 0.14).

CONCLUSIONS

CSFP has a positive, linear relationship with BMI. IOP is not influenced by BMI. If CSFP influences the risk for POAG, then individuals with a lower BMI may have an increased risk for developing POAG. Similarly, a higher BMI may be protective.