Layer Cross-sectional Area Research Articles

Peripapillary RNFL cross-sectional area and its association with other parameters in a Chinese population

BackgroundQuantitative analysis of retinal nerve fibers is important for the diagnosis and treatment of optic nerve diseases. Peripapillary retinal nerve fiber layer (RNFL) cross-sectional area may give a more accurate quantitative assessment of retinal nerve fibers than RNFL thickness but there have been no previous reports of the peripapillary RNFL cross-sectional area or other parameters. The purpose of the current study was to determine peripapillary RNFL cross-sectional area and its association with other factors in an adult Chinese population.MethodsRNFL cross-sectional area was measured during peripapillary circular optical coherence tomography (OCT) scan with a diameter of 12° centered on the optic disc. Correlation between RNFL cross-sectional area and other parameters was evaluated by linear regression analysis in a cross-sectional study of an adult Chinese population.ResultsA total of 2404 eyes from 2404 subjects were examined. Multivariate linear regression analysis showed that larger RNFL cross-sectional area correlated with younger age (p < 0.001), female gender (p = 0.001), no history of diabetes (p = 0.012) and larger optic disc area (p < 0.001).ConclusionsPeripapillary RNFL cross-sectional area is correlated positively with optic disc area, suggesting that eyes with larger optic discs have thicker RNFL. Further studies are needed to confirm whether this correlation is due to differences in the numbers of retinal nerve fibers or other factors.

Analysis of the correlation between peripapillary retinal nerve fiber layer cross-sectional area and myopia in individuals aged 50 years and above

Objective: To measure the peripapillary retinal nerve fiber layer (RNFL) cross-sectional area in individuals aged 50 years and above with different refractive errors, and analyze its correlation with axial length and refractive error. Methods: This was a cross-sectional study conducted as part of the "Beijing Eye Study". The study was population-based and longitudinally designed. In 2001, a cohort of individuals aged 40 years and above from five urban communities in Haidian District and three rural communities in Daxing District, Beijing, were surveyed. Follow-up examinations were conducted in 2011. In this study, the follow-up data from 2011 were collected and analyzed. One eye of each participant was randomly selected, and the participants were categorized into four groups based on their spherical equivalent: emmetropia group (-0.50 D≤spherical equivalent≤0.50 D), low myopia group (-3.00 D≤spherical equivalent<-0.50 D), moderate myopia group (-6.00 D≤spherical equivalent<-3.00 D), and high myopia group (spherical equivalent<-6.00 D). Spectral-domain optical coherence tomography (OCT) was used to perform circular scans with a diameter of 12° centered on the optic disc. ImageJ software and Heidelberg Eye Explorer software were used to calculate the RNFL cross-sectional area. One-way analysis of variance was used to compare the differences in RNFL thickness and RNFL cross-sectional area among different groups. Linear regression analysis was performed to analyze the correlation between RNFL thickness and axial length and spherical equivalent, as well as the correlation between RNFL cross-sectional area and axial length and spherical equivalent. Results: A total of 184 participants (184 eyes) were included in the study, including 88 males and 96 females. The median age was 59 (54, 66) years, with 87 right eyes and 97 left eyes. There were 50 participants (50 eyes) in the emmetropia group, low myopia group, and moderate myopia group, and 34 participants (34 eyes) in the high myopia group. There were no significant differences in age, gender, and eye laterality among the groups (all P>0.05). The RNFL cross-sectional areas in the emmetropia, low myopia, moderate myopia, and high myopia groups were (1.115±0.106), (1.122±0.136), (1.105±0.105), and (1.096±0.106) mm2, respectively, with no significant differences observed (F=0.43, P=0.730). The RNFL thickness in the emmetropia, low myopia, moderate myopia, and high myopia groups were (102.5±9.5), (102.5±12.1), (94.2±8.3), and (90.2±8.9) μm, respectively, with a significant difference observed (F=16.42, P<0.001). Univariate linear regression analysis was performed with spherical equivalent as the independent variable and peripapillary RNFL thickness as the dependent variable, yielding the regression equation: peripapillary RNFL thickness=102.651+1.634 × spherical equivalent (R2=0.21, P<0.001). Similarly, when axial length was used as the independent variable and peripapillary RNFL thickness as the dependent variable, the regression equation was: peripapillary RNFL thickness=174.161-3.147 × axial length (R2=0.18, P<0.001). There was no significant correlation between RNFL cross-sectional area and spherical equivalent (P=0.065) or axial length (P=0.846). Conclusions: There were no significant differences in peripapillary RNFL cross-sectional area among individuals aged 50 years and above with different axial lengths or refractive errors.

Effects of design and coupling parameters on the performance of electromagnetic transducers in round-window stimulation.

Many studies have investigated factors contributing to large variations in the outcomes of round-window (RW) stimulation but most have focused on the floating mass transducer (FMT). To determine whether results for the FMT hold for a fixed-type transducer (FTT), this study constructs two coupled finite element models of the transducer and the human ear that incorporate the cochlear third windows and inner structures of these two electromagnetic transducers. We use these FE models of the human ear and transducers to investigate the influence of four design parameters and coupling conditions for the transducers, i.e., the support's Young's modulus, the coupling layer's cross sectional area and Young's modulus, and the transducer's cross sectional area. The results show that an increase in the support's Young's modulus reduces the output of the FMT but increases that of the FTT. Reducing the cross sectional area and Young's modulus of the coupling layer significantly increases the low-frequency response of the FMT but slightly reduces that of the FTT. Reducing the cross sectional area of the transducer increases the output of the FMT but reduces that of the FTT. This shows that inner structures of electromagnetic transducers should be considered in the optimal design parameters and coupling conditions for RW stimulation.

Impact of Process Variability on Write Error Rate and Read Disturbance in STT-MRAM Devices

Spin-transfer torque magnetic random-access memory (STT-MRAM) is the most promising next-generation memory technology that combines the advantages of mainstream memory technologies, such as SRAM, DRAM, and flash. In the STT-MRAM, a magnetic tunnel junction (MTJ) is used as a bit-cell to store the data, and its magnetic properties have a critical role in thermal noise-aware STT-switching operations. This work analyzes the impact of MTJ material and geometric parameter variations, such as saturation magnetization (MS), magnetic anisotropy (HK), damping factor (α), spin polarization efficiency factor (η), oxide thickness (tOX), free layer thickness (tF), tunnel magnetoresistance (TMR), and cross-sectional area of free layer (AF) variations on write error rate (WER) and read disturbance rate (RDR) for reliable write and read operations, respectively. To evaluate the scalability of MRAM devices, we investigate both WER and RDR with a wide range of MTJ diameters between 90 and 30 nm, which corresponds to mainstream technology nodes from 40 up to 14 nm advance node. In our work, the Fokker-Planck (FP) numerical approach is mainly utilized for an efficient analysis, which allows for parametric variation and evaluates its impact on switching. Although the impact of material and geometric parameter variations on WER is decreased as MTJ scales down from 90 to 30 nm, the variation effect can be still critical with small MTJ diameter, and the most significant influential variation is η, MS, HK, and α in that order. By contrast, the impact of material and geometric parameter variation on RDR increases in MTJ scaling, and we show that negative variations of HK and MS could be a critical bottleneck in 30 and 40 nm MTJ diameters. Our work finally emphasizes the necessity of the WER and RDR analysis by considering the parameter variation in MTJ scaling for practical STT-MRAM development.

Ultrasonography to measure quadriceps muscle in critically ill patients: A literature review of reported methodologies.

Muscle wasting in the intensive care unit (ICU) is common and may impair functional recovery. Ultrasonography (US) presents a modern solution to quantify skeletal muscle size and monitor muscle wasting. However, no standardised methodology for the conduct of ultrasound-derived quadriceps muscle layer thickness or cross-sectional area in this population exists. The aim of this study was to compare methodologies reported for the measurement of quadriceps muscle layer thickness (MLT) and cross-sectional area (CSA) using US in critically ill patients. Databases PubMed, Ovid, Embase, and CINAHL were searched for original research publications that reported US-derived quadriceps MLT and/or CSA conducted in critically ill adult patients. Data were extracted from eligible studies on parameters relating to US measurement including anatomical location, patient positioning, operator technique and image analysis. It was identified that there was a clear lack of reported detail and substantial differences in the reported methodology used for all parameters. A standardised protocol and minimum reporting standards for US-derived measurement of quadriceps muscle size in ICU is required to allow for consistent measurement techniques and hence interpretation of results.

Quality certification and control of polymer laser sintering: layerwise temperature monitoring using thermal imaging

In additive manufacturing (3D printing) of products for aerospace, medical, or other critical applications, the quality of the manufactured part must be “certified” before it can be used. New methods are needed to certify the quality during the fabrication process. The digital 3D quality certificate (3DQC) assures that process monitor values were within specification during the entire fabrication process. This paper proposes an approach for using high resolution infrared thermal imaging to monitor the temperature of individual layers before, during, and after laser scanning. Temperature data is indexed to the part geometry using a binary template created from the sliced 3D model. This data provides a record of the process conditions during the creation of each volume element of the part. Two temperatures are discussed in this paper: the peak temperature achieved during laser scanning and the residual temperature in the layer just before adding the next powder layer. Both of these monitors show a relationship to the geometry of the part, the layer cross-sectional area, and the presence or absence of an underlying solid layer. While both of these temperatures likely relate to part quality, this relationship is not yet understood. Ultimately, this monitor data can be used to control the process, e.g., modify the laser scan or the wait time before recoating, in order to provide more uniform sintering of each volume element of the part.

Predicting Visual Outcomes for Macula-Off Rhegmatogenous Retinal Detachment with Optical Coherence Tomography

Purpose. We evaluated the ability of novel optical coherence tomography (OCT) parameters to predict postoperative best-corrected visual acuity (BCVA) in macula-off rhegmatogenous retinal detachment (RRD) eyes. Methods. We reviewed the medical records of 56 consecutive eyes with macula-off RRD. Clinical findings were analyzed including the relationship between preoperative OCT findings and 6-month postoperative BCVA. Results. Six-month postoperative BCVA was significantly correlated with preoperative findings including retinal height at the fovea, total and inner layer cross-sectional macular area within 2 mm of the fovea, and preoperative BCVA (P < 0.001, P < 0.001, P = 0.001, and P < 0.001, resp.). Multiple regression analysis revealed that the duration of macular detachment and total cross-sectional macular area were independent factors predicting 6-month postoperative BCVA (P = 0.024 and P = 0.041, resp.). Conclusions. Measuring preoperative total cross-sectional area of the macular layer within 2 mm of the fovea with OCT is a useful and objective way to predict postoperative visual outcome in eyes with macula-off RRD.

Retinal nerve fibre layer cross‐sectional area, neuroretinal rim area and body mass index

To examine associations between body mass index, neuroretinal rim area and retinal nerve fibre layer cross-sectional area (RNFLCRA) in a population-based setting. The Central India Eye and Medical Study is a population-based study performed in a rural region of Central India. The study included 4711 subjects (aged 30 + years). A detailed ophthalmic and medical examination was performed. Inclusion criteria for this study were an intra-ocular pressure ≤21 mmHg, open anterior chamber angles and an axial length ≤26.5 mm. Neuroretinal rim area and RNFLCRA were measured by confocal laser scanning tomography. The study included 3959 subjects fulfilling the inclusion criteria. Larger neuroretinal rim area (mean: 1.63 ± 0.32 mm(2) ) was significantly (p = 0.004) associated with a higher body mass index after adjusting for larger disc area (p < 0.001), younger age (p < 0.001), lower intraocular pressure (p < 0.001), and hyperopic refractive error (p < 0.001). Larger retinal nerve fibre layer cross-sectional area (mean:1.29 ± 0.39 mm(2) ) was significantly associated with higher body mass index (p = 0.001) after adjusting for younger age (p < 0.001), shorter axial length (p < 0.001), larger optic disc area (p < 0.001), taller body height (p < 0.001) and male gender (p = 0.04). In a rural Central Indian population, neuroretinal rim area and RNFLCRA as surrogates of the optic nerve fibres were related to a higher body mass index. Because body mass index is associated with cerebrospinal fluid pressure, the higher cerebrospinal fluid pressure may be associated with a larger neuroretinal rim area. It may vaguely point towards an association between cerebrospinal fluid pressure and glaucomatous optic neuropathy.

Measurement and analysis of optic disc parameters in Mongolian and Han healthy subjects with or without family history of glaucoma

Objective To measure optic disc parameters in Mongolian and Han healthy subjects with or without family history of glaucoma,to explore the causes of the differences and their significance in the diagnosis of early glaucoma.Methods Fifteen healthy Mongolian individuals (30 eyes),30 healthy Han individuals (60 eyes) with a family history of open-angle (30 eyes) or angle-closure (30 eyes) glaucoma,and 45 healthy Han individuals (90 eyes) without a family history of glaucoma were enrolled in this study.The 45 healthy Han individuals without a family history of glaucoma included three age-groups:20 to 29 years old group,30 to 39 years old group and 40 to 49 years old group,each group have 15 subjects (30 eyes).Thirteen parameters were measured by Heidelberg retina tomography (HRT) for all subjects,including disc area,cup area,rim area,cup volume,rim volume,cup/disc area ratio,linear cup/disc ratio,mean cup depth,maximum cup depth,cup shape,disc height variation contour,mean retinal nerve fiber layer (RNFL) thickness and optic nerve fiber layer cross-sectional area.The results were analyzed and compared between the above groups.Results There was no statistically significant (t=0.791,P=0.132) of the height variation contour between Mongolian and Han without a family history of glaucoma (20 to 29 years old) group.The other parameters of Mongolian were smaller than Han without a family history of glaucoma (20 to 29 years old) group,but the difference was not statistically significant (t=-1.039,-0.799,-0.840,-1.108,-0.956,-0.695,-0.931,-1.099,-1.074,-0.580,-0.204,-1.425; P＞ 0.05).The parameters in Han with a family history of open-angle glaucoma group were bigger than Han without a family history of glaucoma (30 to 39 years old) group.The differences were statistically significant for disc area,cup area,rim area,cup volume,rim volume,cup area ratio,linear cup/disc ratio,mean cup depth,cup shape measure,nerve fiber layer cross-sectional area (t =4.758,3.187,2.544,2.674,1.798,3.676,2.721,2.715,2.510,2.373; P＜0.05),but were not statistically significant for maximum cup depth,disc height variation contour and mean RNFL thickness (t=1.649,1.565,0.767; P＞0.05).Most parameters in Han with a family history of angle-closure glaucoma group were the same as that in Han without a family history of glaucoma (40 to 49 years old) group,including cup area,rim area,cup volume,rim volume,cup/disc area ratio,linear cup/disc ratio,mean optic cup depth,maximum cup depth,cup shape,disc height variation contour,mean RNFL thickness,optic nerve fiber layer cross-section (t=1.201,1.697,1.000,0.516,0.740,-0.172,-0.070,-0.972,1.530,-0.390,-0.091,0.659; P＞ 0.05) ; but the difference of disc area between these 2 groups was statistically significant (t=2.224,P＜0.05).Conclusions The family history of glaucoma can change the optic disc parameters of healthy individuals,especially those with a family history of open-angle glaucoma.There is no difference of optic disc parameters between healthy Mongolian and Han subjects. Key words: Optic disk/anatomy & histology; Optic disk/physiopathology; Glaucoma/diagnosis

Optic disc topographic analysis in diabetic patients

The aim of our study was to evaluate the optic disc (OD) topographic parameters by using Heidelberg Retina Tomograph II (HRT II) in patients with type 2 diabetes mellitus (DM). The study group consisted of 78 patients with type 2 DM (patient group) and age-sex matched 50 healthy subjects (control group). All patients and controls underwent a detailed ophthalmological examination, automated perimetry, central corneal thickness (CCT) measurement and OD topography by using HRT II. Glycosylated haemoglobin (HbA1c) levels of the diabetic patients were also noted. Age, gender, intraocular pressure and CCT measurements were similar in patients with diabetes and control group. Mean retinal nerve fiber layer thickness (MRNFLT) and retinal nerve fiber layer cross-sectional area (RNFLcsA) parameters were found significantly lower in diabetic patients compared to those of the controls (p = 0.030, p = 0.038). In the patient group, MRNFLT value was found significantly lower in patients with DM duration ≥120 months (p = 0.020) and HbA1c level ≥7 % (p = 0.029). Rim volume, MRNFLT and RNFLcsA values were significantly lower in proliferative diabetic retinopathy group (p = 0.004, p = 0.003, p = 0.001 respectively) and laser treated patients (p = 0.003, p = 0.002, p = 0.004 respectively). In conclusion, poor metabolic control of diabetes, severe DR and received laser therapies cause RNFL damage. Heidelberg Retina Tomograph may help us to detect and follow-up the changes in optic disc and RNFL in diabetic patients.

Assessment of optic disc parameters among healthy adult Malays by Heidelberg Retinal Tomograph II

This study aims to assess the optic disc characteristics in healthy adult Malays and to correlate them with age, gender and refractive errors. Cross-sectional study. A total of 200 voluntary participants (106 women and 94 men) among Malay students aged 20 to 37 years at Health Campus, Universiti Sains Malaysia. The relationship between Heidelberg Retinal Tomograph parameters with age, gender and refractive error were analysed with correlation tests and multiple linear regression analyses. Twelve parameters, that is, disc area, rim area, cup area, cup to disc area, cup volume, rim volume, height variation contour, cup shape measure, mean cup depth, maximum cup depth, mean retinal nerve fibre layer thickness and retinal nerve fibre layer cross-sectional area. Disc area, rim area and cup : disc area ratio averaged 2.24 ± 0.52 (mean ± standard deviation), 1.64 ± 0.32 and 0.25 ± 0.12 mm(2) , respectively. Five parameters (disc area, cup area, cup volume, cup : disc area ratio and mean retinal nerve fibre layer thickness) showed statistically significant difference between men and women. Age was negatively and significantly correlated with rim area with coefficient r = -0.21, P = 0.003. All optic disc parameters were significantly correlated (P < 0.05) with disc area, except cup shape measure. One or more of optic disc parameters were affected significantly by age, gender and disc area in healthy adult Malays' eyes. These factors need to be considered during the evaluation of optic disc.

Comparison of Parameters from Heidelberg Retina Tomographs 2 and 3

To compare stereometric parameters and classification results from the Heidelberg Retina Tomograph version 2 (HRT2); HRT3; and HRT3 Glaucoma Probability Score (GPS), an automated method of obtaining optic nerve head analysis without the need for manual definition of disc margin. Retrospective cross-sectional study. Five hundred four eyes from 281 consecutive subjects (glaucoma, glaucoma suspect, and healthy) evaluated in a glaucoma clinic. All participants had HRT2 scanning of the optic nerve head. Inclusion criteria were scans with good centration and focus, even illumination, an overall quality score by HRT3 of acceptable or better, and standard deviation < 50 mum. A Bland-Altman analysis was used for the comparison of HRT2 and HRT3. From these results, calibration equations were determined to permit conversion of the measurements between devices. The agreement between HRT2 and HRT3 Moorfields regression analysis (MRA) and HRT3 GPS classification methods was measured using kappa statistics. Heidelberg Retina Tomograph version 2 and HRT3 stereometric parameters, MRA, and global GPS. There was a statistically significant difference between HRT2 and HRT3 global disc area, rim area, cup area, rim volume, cup volume, height variation contour, and retinal nerve fiber layer cross-sectional area stereometric parameters. All of those parameters were smaller using HRT3, due to a manufacturer-reported horizontal scaling error of 4% in HRT2 that was corrected in HRT3. kappas for agreement were 0.60 between classifications (within normal limits, borderline, and outside normal limits) of MRA by HRT2 and HRT3 and 0.47 between HRT3 MRA and GPS. The HRT3 generally provided smaller stereometric disc measurements than HRT2. There was no clear conversion between HRT3 and GPS parameters, as the 2 methods for measuring the stereometric parameters differ.

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

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

Sensitivity and specificity of Heidelberg Retinal Tomography II parameters in detecting early and moderate glaucomatous damage: effect of disc size

To determine the efficacy of Heidelberg Retinal Tomography II (HRTII) parameters in differentiating normal eyes from eyes with early or moderate glaucomatous damage. HRTII tests were performed on 70 eyes of 70 patients with early or moderate glaucomatous damage, and 70 eyes of 70 healthy subjects. HRTII stereometric parameters, global and sectorial rim area parameters were recorded. Sensitivity and specificity of each parameter were calculated. Cases were divided into three groups according to disc size as large, medium and small, and mean values of parameters in glaucoma and control groups were compared. Mean disc area was larger in the glaucoma group (P < 0.05). There was a significant difference between the two groups for all stereometric parameters, except height variation contour, mean retinal nerve fibre layer thickness and retinal nerve fibre layer cross-sectional area stereometric parameters. There was also a significant difference between the groups for global, temporal, superior temporal and inferior temporal rim area parameters. In small discs, however, this difference disappeared in all parameters except temporal rim area and superior temporal rim area sectorial parameters. When all the cases were included, the quartet parameters having the highest specificity (80%) and sensitivity (74.3%) were cup volume, rim volume, cup shape measure and height variation contour parameters. Some HRTII parameters have better sensitivity and specificity than the others. It is necessary to pay special attention in evaluating small discs.

Comparison of optic nerve head topography in healthy adults using a Heidelberg retina tomograph and retinal thickness analyzer

To compare optic nerve head topographies measured using a Heidelberg retina tomograph I (HRT) and a retinal thickness analyzer (RTA) and thereby to determine clinical agreement between the two devices. Also, to investigate the reproducibility of optic nerve head measurements using the HRT and RTA. The study included 50 normal left eyes of 50 white adults. Ophthalmologic examination, keratometry, fundus photography, and examination with HRT and RTA were performed. To determine reproducibility, 10 volunteers had repeated examinations after a week. Mean (SD), median, and 5th and 95th percentiles were calculated for the HRT and RTA measurements and differences in measurements between HRT and RTA were tested for statistical significance. Clinical agreement was assessed with limits of agreement and reproducibility by a repeatability coefficient and intraclass correlation coefficient (ICC). Statistically significant differences (P < 0.05) between measurements by HRT and RTA were observed for all topographic parameters, except for rim area (P = 0.051) and height variation contour (P = 0.054). The limits of agreement between HRT and RTA were wide. The repeatability coefficient for HRT was good (< or =0.10) for all parameters, except for retinal nerve fibre layer (RNFL) cross-sectional area (0.28). The repeatability coefficient for RTA was >0.10 for cup area (0.15), rim area (0.19), maximum cup depth (0.13), height variation contour (0.11), and RNFL cross-sectional area (0.14). The ICC was good (> or =90%) for all parameters, except for mean RNFL thickness (89%) for HRT, and height variation contour (84%) for RTA. The observed differences within the limits of agreement were clinically important. Therefore, the two devices cannot be used interchangeably in clinical practice.

The effect of the menstrual cycle on optic nerve head analysis in healthy women

To determine the effect of the menstrual cycle on optic nerve head topographic analysis in normally menstruating, healthy women. The study included single eyes selected randomly from each of 52 healthy women with regular menstrual cycles. All subjects underwent a complete ocular examination. Optic nerve head topographic analyses were performed using a confocal scanning laser ophthalmoscope, the Heidelberg Retinal Tomograph II (HRT II, software version 1.6). The analyses were repeated three times during the menstrual cycle: in the follicular phase (days 7-10 of the cycle), at ovulation, and in the late luteal phase (days 1-3 before menstrual bleeding). Serum oestradiol, progesterone and luteinizing hormone levels were measured at each menstrual phase. Fourteen subjects were excluded from the study. The mean age of the subjects (n = 38) was 25.6 +/- 3.7 years (range 21-34 years). Blood oestradiol levels were significantly lower in the late luteal phase (35.8 pg/ml) (p < 0.0001). The mean disc area of the subjects was 1.94 +/- 0.33 mm(2). The neuroretinal rim area decreased significantly during the luteal phase (p < 0.001). However, the linear cup : disc ratio, cup : disc area ratio and the cup area were significantly higher during the luteal phase (p < 0.001). These observations raise the possibility that sex hormone fluctuations which occur during a normal menstrual cycle in healthy women significantly alter neuroretinal rim area and cup variables of the optic nerve head. These findings should be taken into consideration in the clinical follow-up of young women with glaucoma.

Fluorescein filling defects and quantitative morphologic analysis of the optic nerve head in glaucoma.

To evaluate absolute filling defects of the optic nerve head in normal tension glaucoma (NTG) and primary open-angle glaucoma (POAG) and to compare the filling defects with topographic analysis of the optic disc. Twenty-five patients with NTG, 25 patients with POAG, and 25 age-matched controls were included. Fluorescein angiograms were performed by means of a scanning laser ophthalmoscope. The extent of absolute filling defects of the optic nerve head was assessed using digital image analysis of early-phase angiograms. Topographic measurements of the optic disc were acquired using the Heidelberg Retina Tomograph II. Absolute filling defects were significantly larger (P =.001) and were seen more often (P<.001) in patients with NTG (n = 18) and POAG (n = 19) compared with controls (n = 3). Rim area (P =.006), rim volume (P =.007), cup-disc area ratio (P =.008), linear cup-disc ratio (P =.005), maximum cup depth (P =.002), cup shape measure (P =.03), and nerve fiber layer thickness (P =.008) and cross-sectional area (P =.006) were significantly different between patients with glaucoma and controls. Absolute filling defects were significantly correlated with cup area (r = 0.31; P =.007), rim area (r = -0.38; P<.001), rim volume (r = -0.35; P =.002), cup-disc area ratio (r = 0.49; P<.001), linear cup-disc ratio (r = 0.48; P<.001), cup shape measure (r = 0.27; P =.02), and nerve fiber layer thickness (r = -0.33; P =.004) and cross-sectional area (r = -0.30; P =.009). Fluorescein filling defects of the optic disc are present in NTG and POAG. The extent of these filling defects is correlated with the morphologic disc damage.

Relationship of optic disk topography and visual function in patients withlarge cup-to-disk ratios

Purpose To determine if topographic differences exist between large cup-to-disk ratio (C/D) eyes with standard achromatic automated perimetry (SAP) abnormalities and those with only short-wavelength automated perimetry (SWAP) abnormalities. Design Cross-sectional study. Methods The setting was a referral university-based clinical practice. We selected one eye of 72 patients with a vertical C/D of at least 0.8 by ophthalmoscopy. Patients performed SWAP, SAP, and confocal scanning laser ophthalmoscopy. We compared optic disk topography in eyes with and without visual field abnormalities and controlled for the influence of disk area. Results Disk area was a confounder of many topographic measures. After controlling for disk area, eyes with abnormal SAP had differences in rim volume, cup shape, rim area, retinal nerve fiber layer thickness, and retinal nerve fiber layer cross-sectional area when compared with eyes with normal SAP ( P < .05). Rim volume and rim area were different in the SWAP comparison ( P < .05). Conclusions Investigators should control for disk area when evaluating topographic measures by confocal scanning laser ophthalmoscopy. In eyes with a large C/D, optic disk topography is more glaucomatous in eyes with SAP abnormalities than in those with only SWAP abnormalities. Eyes with large C/D and only SWAP abnormalities may have fewer glaucomatous optic disk changes than such eyes with SAP abnormalities. This indicates that SWAP is likely to correspond to abnormalities in optic disk topography at an earlier stage of glaucomatous optic neuropathy than SAP. Therefore, clinicians should consider SWAP testing in glaucoma suspects to detect glaucomatous visual field loss at an earlier stage of structural loss.

Morphometric characteristics of optic disk with disk hemorrhage in normal-tension glaucoma

PURPOSE: To evaluate the morphometric characteristics of the optic disk in eyes with and without disk hemorrhage in normal-tension glaucoma. METHODS: This was a prospective study conducted at Gifu University Hospital of 50 eyes of 50 patients with normal-tension glaucoma (12 men, 38 women; age, 56.5 ± 14.1 years) who had developed new disk hemorrhage at the time of enrollment and 58 eyes of 58 patients with normal-tension glaucoma (20 men, 38 women; age, 56.7 ± 12.4 years) with no history of disk hemorrhage during the follow-up period of more than 2 years. Age and global indexes of the visual field were matched. We morphometrically compared the optic disk with and without hemorrhage using a scanning laser tomograph. Global and sector analyses were made of the optic disk structural parameters. RESULTS: There was no significant difference in the global values of the disk parameters between the disk hemorrhage and the nonhemorrhage groups. However, the inferotemporal values for the rim area, rim volume, mean retinal nerve fiber layer thickness, and retinal nerve fiber layer cross-section area in the disk hemorrhage group were significantly smaller than those in the nonhemorrhage group ( P < .05). In the disk hemorrhage group, moreover, the values for the rim area, rim volume, and retinal nerve fiber layer cross-section area in the inferotemporal sector with hemorrhage were significantly smaller than those in the same sector without hemorrhage ( P < .05). CONCLUSION: Localized damage of the disk rim and retinal nerve fiber layer at the inferotemporal sector was prominent in eyes with disk hemorrhage.

Scanning Laser Tomography to Evaluate Optic Discs of Normal Eyes

Purpose: To investigate the effects of age, eye refraction, and disc area on topographic parameters of the optic nerve head in normal volunteers, using the Heidelberg Retina Tomograph. Methods: Seventy-seven eyes of 77 normal volunteers were examined by scanning laser tomography. The topographic parameters analyzed were disc area, cup area, cup/disc area ratio, rim area, cup volume, rim volume, mean cup depth, maximum cup depth, cup shape measure, height variation contour, mean retinal nerve fiber layer thickness (MnRNFLT), and retinal nerve fiber layer (RNFL) cross-section area. The effect of age, refraction, and disc area on each parameter was analyzed by the multiple linear regression model. Results: Significant declines in MnRNFLT and RNFL cross-section area were found with increasing age ( P < .05). The mean cup depth and maximum cup depth were significantly deeper in myopic subjects ( P < .05). Large discs had large cup area, cup/disc area ratio, rim area, cup volume, mean cup depth, cup shape measure ( P < .01), and maximum cup depth ( P < .05). The MnRNFLT was smaller in large discs ( P < .01). Rim volume was unaffected by age, refraction, or disc area. Conclusions: The age, refraction, and disc area were related to several optic disc parameters obtained by the Heidelberg Retina Tomograph. Because of these relationships, care should be taken to analyze the appearance of the optic disc on the basis of these parameters in patients with glaucoma or other diseases. Rim volume appears to be a good parameter for evaluating the optic disc without considering age, refraction, or disc area.