Central Corneal Thickness as Measured by Spectral-Domain Optical Coherence Tomography in Glaucomatous and Non-Glaucomatous Eyes

Objective: Accurate measurement of intraocular pressure (IOP) is an integral part of glaucoma diagnosis and management. IOP measurement is influenced by central corneal thickness (CCT). Aims: This study aims to compare the CCT as measured by spectral-domain (SD) optical coherence tomography (OCT) in glaucomatous and non-glaucomatous eyes and to compare the CCT in various types of glaucoma.Settings and Design: It was a prospective case–control study conducted at a tertiary hospital in Mangaluru.Materials and Methods: Patients diagnosed with primary open-angle glaucoma (POAG), normal-tension glaucoma (NTG), and ocular hypertension (OHT) were taken as cases. They underwent CCT measurement using SD-OCT anterior segment cube program after a complete ophthalmic evaluation.Statistical Analysis: Data were analyzed using SPSS for Windows, version 8.0 using Kruskal–Wallis test, Mann–Whitney U-test, and Chi-square test. P < 0.05 was considered statistically significant.Results: Forty cases (80 eyes) were included in the study, of which 26 had POAG, 12 had NTG, and 2 had OHT. Controls were 80 patients with healthy corneas. The mean CCT in POAG group was 518.69 μm, in NTG was 503.33 μm, and in OHT group 542.5 μm. The mean CCT among controls was 523.97 μm. The differences in CCT in all the four groups were statistically insignificant. The IOP was corrected for CCT and the difference between the two was statistically significant.Conclusions: CCT is higher in OHT and lower in NTG. Our study did not find any statistically significant difference between the three types of open-angle glaucoma

Cognitive performance of primary open-angle glaucoma and normal-tension glaucoma patients / Desempenho cognitivo em pacientes com glaucoma primário de ângulo aberto e glaucoma de pressão normal

ABSTRACT Purpose: To assess cognitive performance differences among primary open-angle glaucoma (POAG) patients, normal-tension glaucoma (NTG) patients, and healthy control (C) subjects. Methods: A total of 60 participants (20 POAG, 20 NTG, and 20 C subjects) were included in this study. A detailed ophthalmologic examination was performed on all participants. A spectral domain-optical coherence tomography (SD-OCT) system was used to measure the ganglion cell-inner plexiform layer (GC-IPL) and retinal nerve fiber layer (RNFL) thicknesses. To assess the cognitive performance of all participants, detailed neurological examinations, including the mini-mental state examination (MMSE), were performed by the same neurologist. Results: There were no significant differences among the groups in terms of age (p =0.348) or gender (p =0.935). The mean RNFL thicknesses were significantly different among the groups (85.2 ± 14.7, 76.8 ± 10.3, and 91.4 ± 7.7 µm in the POAG, NTG, and C subjects, respectively; p <0.001). The mean GC-IPL thicknesses were 77.5 ± 9.7 µm in the POAG group, 73.4 ± 7.8 µm in the NTG group, and 78.8 ± 3.8 µm in the C group. Differences among the groups were not statistically significant (p =0.085). MMSE scores were 26.1 ± 1.4, 25.7 ± 2.3, and 28.8 ± 0.9 in the POAG, NTG, and C groups, respectively. There were significant differences among the three groups (p <0.001). Specifically, there were significant differences between the NTG and C groups (p <0.001), and between the POAG and C groups (p =0.001). There was no significant difference between the POAG and NTG groups (p =0.595). Conclusions: There appear to be similar risk factors in glaucoma and neurodegenerative disorders that cause deterioration in cognitive performance. Comparing the low MMSE scores of the POAG and NTG patients with the scores of healthy C participants supports our hypothesis. Consequently, it is recommended that a neurologist should also examine glaucoma patients.

RESUMO Objetivos: Avaliar as diferenças de desempenho cognitivo entre pacientes com glaucoma primário de ângulo aberto (POAG), glaucoma de pressão normal (NTG) e controle de indivíduos saudáveis (C). Métodos: Um total de 60 pessoas (20 POAG, 20 NTG e 20 indivíduos saudáveis) foram incluídos neste estudo. Um exame oftalmológico detalhado foi realizado em todos os participantes. Um sistema de tomografia de coerência óptica de domínio espectral (SD-OCT) foi utilizado para medir as espessuras da camada de células ganglionares plexiforme interna (GC-IPL) e da camada de fibras nervosas da retina (RNFL). Para avaliar o desempenho cognitivo de todos os participantes, foi realizado pelo mesmo neurologista um exame neurológico detalhado, incluindo mini-exame do estado mental (MMSE). Resultados: Não houve diferenças significativas entre os grupos em termos de idade (p=0,348) e sexo (p=0,935). Espessuras médias da RNFL foram significativamente diferentes, sendo 85,2 ± 14,7, 76,8 ± 10,3 e 91,4 ± 7,7 µm nos grupos POAG, NTG e controles, respectivamente (p<0,001). As espessuras médias da GC-IPL observadas foram 77.5 ± 9.7 μm no grupo POAG, 73,4 ± 7,8 µm no grupo NTG e 78,8 ± 3,8 µm nos controlos. As diferenças entre os grupos não foram estatisticamente significantes (p=0,085). Graduações do MMSE foram 26,1 ± 1,4, 25,7 ± 2,3 e 28,8 ± 0,9 nos grupos POAG, NTG e controles, respectivamente. Houve diferenças significativas entre os três grupos (p<0,001). Houve diferença significativa entre NTG e saudáveis (p<0,001). Houve diferença significativa entre POAG e saudáveis (p=0,001). Não houve diferença significativa entre o POAG e NTG (p=0,595). Conclusões: Parecem haver fatores de risco semelhantes no glaucoma e nos distúrbios neurodegenerativos que causam deterioração no desempenho cognitivo. Comparando a baixa graduação do MMSE de pacientes com POAG e NTG com controles saudáveis referenda nossa hipótese. Consequentemente recomenda-se que um neurologista também examine os pacientes de glaucoma.

Clinical value of OCT in the diagnosis of patients with normal tension glaucoma / 中国基层医药

Objective To analyze the application value of optical coherence tomography (OCT)in the diagnosis of normal tension glaucoma (NTG).Methods 50 NTG patients (92 eyes)were selected as control group, at the same period 50 cases in our hospital physical examination center for the health examination were selected as the observation group.The optic disc and retinal nerve fiber layer thickness were measured by OCT.The disc diameter, disc area,depending on the cup diameter,optic cup area in the optic disc parameters were observed and compared between the two groups.Results The optic disc diameter between the control group and the observation group had no significant difference (t =1.02,P >0.05),the differences among the remaining nine parameters were significant (t =3.11,2.85,5.63,5.21,4.13,3.06,3.10,6.58,4.36,all P <0.05).Conclusion OCT can measure and analyze the optic disc and retinal nerve fiber layer quantitatively,it is reproducible,clinical early diagnosis of NTG is of great significance,it is worth popularization and application.

Detecting the Progression of Normal Tension Glaucoma: A Comparison of Perimetry, Optic Coherence Tomography, and Heidelberg Retinal Tomography

PURPOSE: We compared the abilities of Stratus optical coherence tomography (OCT), Heidelberg retinal tomography (HRT) and standard automated perimetry (SAP) to detect the progression of normal tension glaucoma (NTG) in patients whose eyes displayed localized retinal nerve fiber layer (RNFL) defect enlargements. METHODS: One hundred four NTG patients were selected who met the selection criteria: a localized RNFL defect visible on red-free fundus photography, a minimum of five years of follow-up, and a minimum of five reliable SAP, Stratus OCT and HRT tests. Tests which detected progression at any visit during the 5-year follow-up were identified, and patients were further classified according to the state of the glaucoma using the mean deviation (MD) of SAP. For each test, the overall rates of change were calculated for parameters that differed significantly between patients with and without NTG progression. RESULTS: Forty-seven (45%) out of 104 eyes displayed progression that could be detected by red-free fundus photography. Progression was detected in 27 (57%) eyes using SAP, 19 (40%) eyes using OCT, and 17 (36%) eyes using HRT. In early NTG, SAP detected progression in 44% of eyes, and this increased to 70% in advanced NTG. In contrast, OCT and HRT detected progression in 50 and 7% of eyes during early NTG, but only 30 and 0% of eyes in advanced NTG, respectively. Among several parameters, the rates of change that differed significantly between patients with and without progression were the MD of SAP (p = 0.013), and the inferior RNFL thickness (p = 0.041) and average RNFL thickness (p = 0.032) determined by OCT. CONCLUSIONS: SAP had a higher detection rate of NTG progression than other tests, especially in patients with advanced glaucoma, when we defined progression as the enlargement of a localized RNFL defect. The rates of change of the MD of SAP, inferior RNFL thickness, and average RNFL thickness differed between NTG patients with and without progression.

Comparison of Risk Factors for Initial Central Scotoma versus Initial Peripheral Scotoma in Normal-tension Glaucoma

PURPOSE: To investigate the risk factors for initial central scotoma (ICS) compared with initial peripheral scotoma (IPS) in normal-tension glaucoma (NTG). METHODS: Fifty-six NTG patients (56 eyes) with an ICS and 103 NTG patients (103 eyes) with an IPS were included. Retrospectively, the differences were assessed between the two groups for baseline characteristics, ocular factors, systemic factors, and lifestyle factors. Also, the mean deviation of visual field was compared between the two groups. RESULTS: Patients from both ICS and IPS groups were of similar age, gender, family history of glaucoma, and follow-up periods. Frequency of disc hemorrhage was significantly higher among patients with ICS than in patients with IPS. Moreover, systemic risk factors such as hypotension, migraine, Raynaud's phenomenon, and snoring were more prevalent in the ICS group than in the IPS group. There were no statistical differences in lifestyle risk factors such as smoking or body mass index. Pattern standard deviation was significantly greater in the ICS group than in the IPS group, but the mean deviation was similar between the two groups. CONCLUSIONS: NTG Patients with ICS and IPS have different profiles of risk factors and clinical characteristics. This suggests that the pattern of initial visual field loss may be useful to identify patients at higher risk of central field loss.

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 fi eld 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 pa􀄴 erns of disc cupping and visual fi eld loss, there is much overlap of the clinical fi ndings in NTG with POAG, suggesting that NTG is likely part of a continuum of open angle glaucomas. However, IOP modifi cation 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 modifi cation of both IOP and IOP-independent risk factors, current eff orts to develop IOP-independent neuroprotective treatments have not yet proven to be eff ective in humans.

Comparison of the Thickness of the Lamina Cribrosa and Vascular Factors in Early Normal-tension Glaucoma with Low and High Intraocular Pressures

PURPOSE: To compare the thickness of the lamina cribrosa (LC) and vascular factors of early normal-tension glaucoma (NTG) patients with high and low intraocular pressure (IOP) that are expected to be associated with the development of glaucoma. METHODS: Seventy-one Korean NTG patients with low IOP (the highest IOP 15 mmHg, 31 patients) were included in this study. The thickness of LC and vascular factors were compared. The thickness of the LC was measured using the enhanced depth imaging method with spectral domain optical coherence tomography (Heidelberg Spectralis). RESULTS: The mean thickness of the central LC was 190.0 +/- 19.2 microm in the low IOP group and 197.8 +/- 23.6 microm in the high IOP group, but there was no statistical significant difference between the two groups (p > 0.05). The prevalence of self-reported Raynaud phenomenon was significantly higher in the low IOP group (33.0%) than the high IOP group (10.3%, p = 0.04). CONCLUSIONS: The laminar thickness did not significantly differ between the high and low IOP groups. However, the prevalence of Raynaud phenomenon was higher in the low IOP groups. These results suggest that the development of glaucoma with low IOP patients may be more influenced by peripheral vasospasm, such as Raynaud phenomenon, rather than laminar thickness in NTG.

Patterns of Subsequent Progression of Localized Retinal Nerve Fiber Layer Defects on Red-free Fundus Photographs in Normal-tension Glaucoma

PURPOSE: To investigate patterns of subsequent progression of localized retinal nerve fiber layer (RNFL) defects and to quantify the extent of progression in normal-tension glaucoma (NTG) patients. METHODS: Thirty-three eyes of 33 consecutive NTG patients who had shown continuous progression of localized RNFL defect on serial red-free fundus photographs were selected for the study. Patterns of subsequent progression of localized RNFL defects were categorized, and extents of progression were quantified. Serial evaluations of disc stereophotographs and visual fields were also performed to detect progression. RESULTS: The most common pattern was continuous widening of the defect towards the macula (n = 11, 33.3%) followed by sharpening of the defect border after widening of the defect towards the macula (n = 5, 15.2%), continuous widening of the defect away from the macula (n = 2, 6.1%), and deepening of the defect after appearance of a new defect (n = 2, 6.1%). Four eyes (12.1%) simultaneously showed two patterns of subsequent progression. In 13 eyes that showed continuous widening of the defect, subsequent angular widening towards the macula and away from the macula were 9.2 ± 6.0degrees (range, 1.1degrees to 24.4degrees; n = 11) and 5.2 ± 4.9degrees (range, 0.3degrees to 11.3degrees; n = 2), respectively. Thirty-two eyes showed no progression of optic disc cupping. Out of the 21 eyes in which Humphrey central 30-2 threshold visual field tests were performed after progression of RNFL defects, 15 eyes showed no deterioration in the visual field. CONCLUSIONS: There were nine patterns of subsequent progression of localized RNFL defects. Among them, continuous RNFL loss proceeding temporally was the most common one. Initial progression of the defect proceeded temporally, especially in the defect located at the inferior fundus, might be at a risk of further RNFL loss temporally.

The Efficacy of a Monocular Drug Trial in Normal-Tension Glaucoma

PURPOSE: To evaluate the efficacy of a monocular drug trial in eyes with normal-tension glaucoma (NTG). METHODS: This prospective study enrolled 74 patients with NTG. The monocular drug trial was started using latanoprost 0.005% for one week. If the intraocular pressure (IOP) reduction was greater than 15%, the same medication was administered to both eyes for one month. The unadjusted change and adjusted change (the change in the treated eye minus the change in the contralateral eye) in IOP were evaluated, and the predictors of IOP response were analyzed by multivariate linear regression. RESULTS: Among the initial 74 patients, 31 (41.9%) were included; others were excluded because they did not meet the requisite conditions. The most significant predictors of IOP response in the initial eye and subsequent eye were the baseline IOPs in both eyes (beta = 0.907, 0.771, respectively). The adjusted change in IOP of the initial eye had greater association (beta = 0.589) with the IOP after monocular trial in the initial eye than that of unadjusted IOP change (beta = 0.279). The adjusted change in IOP also had greater predictability (beta = 0.348) for IOP after monocular trial in the subsequent eye than that of the unadjusted IOP change (beta = 0.090). CONCLUSIONS: Although the monocular trial in NTG patients had limited efficacy due to its stringent conditions, it was useful for evaluating the IOP response in the initial eye and for predicting the IOP response in the subsequent eye.

Circulating Total Glutathione in Normal Tension Glaucoma Patients: Comparison with Normal Control Subjects

PURPOSE: Oxidative stress plays a critical role in the pathogenesis of glaucoma. Glutathione is a major antioxidant molecule present in intracellular or extracellular space. Herein, we aimed to examine circulating glutathione level in normal tension glaucoma (NTG), which comprises the largest proportion of glaucoma disease in the Korean population. METHODS: Nineteen NTG patients (NTG group) and 30 age- and gender-matched normal control subjects (control group) were included. Antecubital venous puncture was performed between 8 and 10 o'clock in the morning to obtain a 4 mL venous blood sample. Total glutathione level was measured by the spectrophotometric method at 412 nm. Correlation of total glutathione level with mean deviation and pattern standard deviation from the Humphrey visual field test was analyzed in the NTG group. RESULTS: Total glutathione level in circulating blood was 524.02 +/- 231.09 nmol and 586.06 +/- 156.08 nmol in the NTG group and the control group, respectively. The difference between these values was not statistically significant (p = 0.121, F = 2.212). Age had no significant effect on circulating total glutathione level in either the NTG group (p = 0.171, r = -0.328) or the control group (p = 0.380, r = -0.166). In the NTG group, circulating total glutathione level had no significant relationship with mean deviation (p = 0.226, F = 1.636) and pattern standard deviation (p = 0.200, F = 1.766) after correcting for age and gender. CONCLUSIONS: In NTG patients, circulating total glutathione levels were not different compared to those of normal subjects.

Circadian Blood Pressure and Intraocular Pressure Patterns in Normal Tension Glaucoma Patients with Undisturbed Sleep

PURPOSE: To investigate and compare the circadian pattern of blood pressure (BP), intraocular pressure (IOP) and mean ocular perfusion pressure (MOPP) while experiencing undisturbed sleep in normal-tension glaucoma (NTG) and non-glaucoma control patient groups. METHODS: Twenty-four eyes from 24 patients diagnosed with NTG and 22 eyes from 22 control group patients were enrolled. Systolic BP, diastolic BP and IOP were measured every two hours except for the period of time from 1 AM to 7 AM in the NTG group and from 11 PM to 7 AM in the control group over a one-day period. IOP and hemodynamic parameters were then compared between the two groups. NTG patients were subdivided according to the degree of morning BP dip and IOP, and hemodynamic parameters and visual field indices (mean deviation and pattern standard deviation) were also compared among these subgroups. RESULTS: There were no significant differences in mean systolic BP, mean diastolic BP and mean arterial pressure (MAP) between the NTG and the control groups. The NTG group showed a significantly large morning BP dip compared to the control group (7.1+/-4.2% vs. 3.8+/-3.4%, p=0.022). However, there were no significant differences in mean or fluctuation of MOPP between the two groups. Morning over-dippers showed significantly large MAP and MOPP fluctuations compared to non-dippers and dippers, while there were no significant differences in visual field indices among the three subgroups. CONCLUSIONS: NTG patients showed significant morning BP dips compared to the control group. The marked morning BP dip was associated with significantly large MAP or MOPP fluctuations but was not associated with visual field indices.

The Relationship between Open Angle Glaucoma and Refractive Errors

Among many suggestive risk factors for the development of open angle glaucoma, myopia is a common clinical entitiy and seems to be increasing today. The authors analysed the prevalence of myopia in patients with open angle glaucoma and compared with normal population of similar age. The results were as follows 1. Fifty-one eyes(82.3%) with POAG, seventy eyes(74.5%) with LTG and thirty-five eyes(87.5%) with OHT were myopia. 2. The percentage of myopia in eyes with POAG, LTG and OHT was greater than that of reported in a normal population of similar age(32.2%). Especially, the percentage of myopia greater than -3.0 diopter among myopias was 52.9% in POAG, 30.0% in LTG, 48.6% in OHT and only 17.3% in normal control groups.

Probability of global indices in low tension glaucoma

To know the pattern of visual field (VF) defect of low tension glaucoma (LTG), its diffuse and localized VF defects were compared using the significance values (p-value) of mean deviation (MD) and corrected pattern standard deviation (CPSD), which are calculated with STATPAC in Humphrey Visual Field Analyser. Sixteen eyes of LTG were enrolled and 34 eyes of primary open angle glaucoma (POAG) were used as controls. The degree of VF defects in LTG and POAG was relatively mild with the p-value of MD equal to or greater than 1%. Neither mean MD nor mean CPSD of LTG was significantly different from each of POAG (p > 0.8 and p > 0.2, respectively). Comparing the p-values of MD and CPSD, many patients showed more significant p-value of MD in LTG and POAG (62.5% and 61.8%, respectively). However, relatively more severe defect of CPSD tended to occur more frequently in LTG than in POAG (25% and 5.9%, respectively, chi-square = 4.964, p < 0.09). The relation between p-values of MD and CPSD was not significantly influenced by the intraocular pressure, MD or vertical cup to disc ratio in either LTG or POAG.

The Prevalence of Glaucoma in Korean Careermen

The Epidemiological study of glaucoma in Korean is essential because the prevalence and distribution of glaucoma can be different among race and country. We surveyed the prevalence and distribution of glaucoma in Korean careerrnen aged 20 years or older who visited Yongdong Severance Hospital to undergo a regular physical examination during the year of 1992 and the total number of subjects examined was 4959 adults. A mainstay of the screening consisted of applanation tonometry and direct ophthalmoscopy, followed by automatic perimetry as a recall examination. Patients with suspected abnormalities in either the IOP >or=22mmHg or the optic disc findings such as high cup/disc ratio (>or=0.7) were referred for recall examination as the second stage of the visual field test. Overall prevalence of glaucoma obtained was 2.04% (101 patients) and the most common type of glaucoma was low tension glaucoma, 1.71% (85 patients). The prevalence of glaucoma increase with aging especially in low tension glaucoma.

The effect of Nifedipine (Nipine(R)) in the Visual Field of the Low Tension Glaucoma Patient

Nifedipine is the Ca++ channel blocker, of which action mechanism is blocking the calcium influx through the smooth muscle of vessels. It is known that Nipine(R) improve the visual field by increasing blood supply to the optic nerve with dilatation of vessels in low tension glaucoma patient whose visual field loss is thought to be caused by the ischemic change of optic nerve. We have clinically evaluated the sensitivities of visual fields of 7 cases (11 eyes) of low tcnsion glaucoma, who were medicated with Nipinetension glaucoma patient whose visual field loss is thought to be caused by the ischemic change of optic nerve. We have clinically evaluated the sensitivities of visual fields of 7 cases (11 eyes) of low tcnsion glaucoma, who were medicated with Nipine(R), 1Omg Tid per os for more than 2 weeks. The visual fields were tested at least 3 times or more with Humphrey automatic perimetry (Allergan, Statpac) and were divided into 10 sectors according to the nerve fiber bundles. In each sector, we analyzed the change of light sensitivity and global index, then compared by Student Pared t-Test. After medication of Nipine(R), improvements of mean light sensitivity in total sectors were found in 7 eyes among the 11 eyes and also superonasal portion of their visual field was more recovered than the other portions and they showed the improvement of the mean deviation but it was not significant.

Trabeculectomy in Low-tension Glaucoma

I analyzed the changes of visual function of 49 eyes of 38 patients with low-tension glaucoma (LTG) who underwent trabeculectomy and had been followed for at least 3 years at Wills Eye Hopsital. The results were as follows: 1. Average IOP was 18.1 mmHg preoperatively and decreased by 5.0, 4.9 and 4.4 mmHg respectively at 1, 3 and 5 years postoperatively. 2. Postoperative visual acuity decreased in 9 eyes (23%) and 7 eyes (35%) respectively at 3 and 5 years. 3. Postoperative visual field improved in 18 eyes (42%) and 5 eyes (22%) respectively at 1 and 5 years. However it progressed in 9 eyes (23%) and 9 eyes (39%) respectively at 3 and 5 years. 4. In terms of postoperative complications, choroidal detachment developed in 3 cases (6%), cataract requiring extraction in 11 cases and there were no cases requiring reoperation during 3 years after operation. From these results, whereas lOP decreased continually by 25% for 5 years, visual field progressed in 39% of cases at 5 years. However in light of low rate of both complication and reoperation together with high visual field improvement, if LTG persists despite medication, trabeculectomy is recommended to stop the progression of visual field.