Retinal Nerve Fiber Layer Cross-sectional Area Research Articles

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.

Baseline structural characteristics of the optic nerve head and retinal nerve fiber layer are associated with progressive visual field loss in patients with open-angle glaucoma.

AimsTo examine the relationship between baseline structural characteristics of the optic nerve head (ONH) and retinal nerve fiber layer (RNFL) and functional disease progression in patients with open-angle glaucoma (OAG) over 5 years.Methods112 OAG patients were prospectively examined at baseline and every 6 months over a period of five years. Structural glaucomatous changes were examined with optical coherence tomography (OCT) and Heidelberg retinal tomography-III (HRT-III), and functional disease progression with automated perimetry (Humphrey visual fields). Cox proportional hazard models were used to assess the relationship between baseline structural measurements and functional disease progression.ResultsFrom baseline over a 5-year period, statistically significant increases were found in OCT disc (D) area (p<0.001), cup (C) area (p<0.001), C/D area ratio (p<0.001), C/D horizontal ratio (p<0.001), C/D vertical ratio (p = 0.018), and a decrease in superior RNFL thickness (p = 0.008). Statistically significant increases were found in HRT-III C volume (p = 0.021), C/D area ratio (p = 0.046), mean C depth (p = 0.036), C shape (p = 0.008), and height variation contour (p = 0.020). Functional disease progression was detected in 37 of the 112 patients (26 of European descent and 11 of African descent; 33%). A statistically significant shorter time to functional progression was seen in patients with larger baseline OCT D area (p = 0.008), C area (p = 0.003), thicker temporal RNFL (p = 0.003), and in patients with a larger HRT-III C area (p = 0.004), C/D area ratio (p = 0.004), linear C/D ratio (p = 0.007), C shape (p = 0.032), or smaller rim area (p = 0.039), rim volume (p = 0.005), height variation contour (p = 0.041), mean RNFL thickness (p<0.001), or RNFL cross-sectional area (p = 0.002).ConclusionBaseline ONH and RNFL structural characteristics were associated with a significantly shorter time to functional glaucomatous progression and visual field loss through the five-year period in OAG patients.

Topographical profiles of macula and optic nerve head in concomitant strabismus patients as measured using OCT and CSLO

Investigate morphological changes of macula and optic nerve head (ONH) in concomitant strabismic patients using optical coherence tomography (OCT) and confocal scanning laser ophthalmoscopy (CSLO). A cross-sectional study conducted from April 2017 to February 2018 at the Zhongshan Ophthalmic Center, Sun Yat-sen University. Spectral-domain (SD)-OCT and CSLO were used to observe morphological changes of macula and ONH in concomitant strabismic patients with normal vision and healthy controls. In each subject, a 6-mm diameter zone centered at the fovea was scanned and topographical images of the ONH and peripapillary retina were generated. Fundus parameters were recorded and analyzed. A total of 138 cases, including 29 patients with concomitant esotropia (ET), 38 constant exotropia (XT), 42 intermittent exotropia (IXT), and 29 healthy controls, were recruited. Compared with controls, OCT revealed that the thickness of nasal intraretinal layers (IRLs) in ET patients was significantly increased, particularly in ganglion cell layer (GCL) and inner nuclear layer (INL). In XT patients, the temporal half of outer retinal layers (ORLs) showed significant increases in thickness. CSLO findings revealed significant changes in the ONH of ET patients consisting of a thinner retinal nerve fiber layer (RNFL) and a decreased RNFL cross-sectional area, height variation contour, maximum contour depression, and contour line modulation (CLM) temporal-superior area. The nasal-superior cup area and rim volume in XT patients were significantly increased. Topographical profiles of the macula and ONH in concomitant strabismic patients with normal vision present with specific regularities.

Comparison of optic nerve head topography in normal eyes using confocal laser scanning tomograph and retinal thickness analyzer

Background: To compare optic nerve head topography measurements by Heidelberg retina tomograph I (HRT) and retinal thickness analyser (RTA) and thereby to determine clinical agreement between the devices. To investigate reproducibility of measurements for HRT and RTA. To obtain our own HRT and RTA database for comparison of healthy and glaucomatous eyes. Methods: The study included 100 normal eyes of 50 white adults of both sexes (mean age of 55.5 [SD 9.5] years). Ophthalmologic examination, fundus photography, HRT and RTA examinations were performed. To determine reproducibility 10 volunteers repeated the examination after a week. For HRT and RTA measurements mean (SD), median, 5th and 95th percentile, range and coefficient of variation were calculated. Differences in topographic parameters between HRT and RTA were tested for significance. Clinical agreement was assessed with »limits of agreement« and reproducibility expressed by repeatability coefficient and intraclass correlation coefficient (ICC). Results: Significant differences (p 0.10 for RTA parameters 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). ICC was good (> 90%) for all parameters, except for mean RNFL thickness (89%) for HRT and height variation contour (84%) for RTA. Conclusions: The two devices cannot be used interchangeably. At present, clinical usefulness of HRT is superior to RTA due to better reproducibility of measurements, better software support, shorter duration of the examination and good comparability of our HRT database with the database included in the latest HRT software version. At the moment RTA is using the same database as HRT. Therefore, our RTA database provides a new basis for comparison of optic disc characteristics between healthy and glaucomatous eyes.

Experimental Glaucoma Causes Optic Nerve Head Neural Rim Tissue Compression: A Potentially Important Mechanism of Axon Injury

PurposeWe tested the hypothesis that experimental glaucoma (EG) results in greater thinning of the optic nerve head (ONH) neural rim tissue than the peripapillary retinal nerve fiber layer (RNFL) tissue.MethodsLongitudinal spectral-domain optical coherence tomography (SDOCT) imaging of the ONH and peripapillary RNFL was performed every other week under manometric IOP control (10 mm Hg) in 51 nonhuman primates (NHP) during baseline and after induction of unilateral EG. The ONH parameter minimum rim area (MRA) was derived from 80 radial B-scans centered on the ONH; RNFL cross-sectional area (RNFLA) from a peripapillary circular B-scan with 12° diameter.ResultsIn control eyes, MRA was 1.00 ± 0.19 mm2 at baseline and 1.00 ± 0.19 mm2 at the final session (P = 0.77), while RNFLA was 0.95 ± 0.09 and 0.95 ± 0.10 mm2, respectively (P = 0.96). In EG eyes, MRA decreased from 1.00 ± 0.19 mm2 at baseline to 0.63 ± 0.21 mm2 at the final session (P < 0.0001), while RNFLA decreased from 0.95 ± 0.09 to 0.74 ± 0.19 mm2, respectively (P < 0.0001). Thus, MRA decreased by 36.4 ± 20.6% in EG eyes, significantly more than the decrease in RNFLA (21.7 ± 19.4%, P < 0.0001). Other significant changes in EG eyes included increased Bruch's membrane opening (BMO) nonplanarity (P < 0.05), decreased BMO aspect ratio (P < 0.0001), and decreased MRA angle (P < 0.001). Bruch's membrane opening area did not change from baseline in either control or EG eyes (P = 0.27, P = 0.15, respectively).ConclusionsOptic nerve head neural rim tissue thinning exceeded peripapillary RNFL thinning in NHP EG. These results support the hypothesis that axon bundles are compressed transversely within the ONH rim along with glaucomatous deformation of connective tissues.

Characteristics of optic disc parameters and its association in normal Chinese population: the Handan Eye Study

Background Assessment of the optic disc and retinal nerve fiber layer (RNFL) is essential for the diagnosis and monitoring of glaucoma. Knowledge of normal optic disc topography provides a benchmark for evaluating glaucomatous pathologic changes, especially in its early stages. The purpose of this study was to evaluate the characteristics and correlation factors of the optic disc parameters using the Heidelberg Retina Tomograph II (HRT II) in a large sample of normal eyes of adult Chinese subjects. Methods Disc data were obtained from 6 830 subjects aged &gt;30 years from the Handan Eye Study. All participants underwent comprehensive eye examinations and physical examinations. The associations of gender, age, body mass index, blood pressure, waist-to-hip ratio; refractive error, intraocular pressure, axial length, and disc area were assessed using simple and multiple regression analysis. The correlation between HRT II parameters was evaluated. Results Of the 7 557 eligible subjects, 6 830 took part in the study (90.4% response rate) and 2 633 normal eyes with good-quality HRT II images were selected. The mean disc area was 2.28 mm2 (standard deviation (SD) 0.43) and mean neural rim area was 1.80 mm2 (SD 0.29). In multiple regression analysis, optic disc area significantly correlated with age, gender, and axial length (P &lt;0.001). All optic disc parameters showed a significant correlation with disc area (0.054 &lt;r &lt;0.736, P &lt;0.01). The association between mean RNFL thickness and rim area is statistically significant but not strong (regression linear equation: rim area = 1.42 × mean RNFL thickness + 1.32 mm2, P &lt;0.001; R 2=0.070). The global RNFL cross-sectional area was significantly associated with global rim area (regression linear equation: rim area = 1.14× RNFL cross-sectional area + 0.44 mm2, P &lt;0.001; R 2 =0.271). Conclusions The optic disc area in rural Chinese population is larger than reported in white and Japanese populations, similar to that of Indian population and urban Chinese population. Most optic disc measurements were moderately or weakly affected by disc area. In addition to the RNFL, there may be other factors affecting the rim area. The relationship between optic disc and axial length may suggest a link between larger disc area, thinning of the lamina cribrosa, and increased glaucoma susceptibility in myopic eyes.

Effect of surgery-lowing intraocular pressure on optic nerve head parameters and retinal nerve fiber layer thickness

Background Lowing intraocular pressure (IOP) is the only effective treating method in glaucoma.Making sure the change of optic disc parameters and retinal nerve fiber layer thickness(RNFLT) in primary open-angle glaucoma (POAG) patients after IOP reduced can provide objective evidence for evaluating the effect of lowing-IOP on the function of optic nerve.Objective The present study was to evaluate the change of optic disc parameters and RNFLT in POAG patients after trabeculectomy,and analyze the affecting factors of image parameters.Methods A serial case-observational study was adapted.Forty eyes of 39 patients with POAG underwent trabeculectomy were recruited in the study.IOP was examined and perimetry was performed before operation and 2 weeks,1 month,3 months,6 months and 1 year after surgery.Optical parameters and RNFLT were measured using Heidelberg retina tomography (HRT) and optical coherence tomography (OCT) in above-mentioned time points.The correlations between lowing-IOP range or disease severity and optical disc parameters or mean RNFLT (mRNFLT) were analyzed by Pearson linear correlation.Results Mean IOP of the 40 eyes was (32.77±8.64) mmHg before operation and (12.45 ±3.65) mmHg,(13.05±3.90) mmHg,(13.42± 3.33) mmHg,(14.22± 2.60) mmHg and (14.74±2.46)mmHg 2 weeks,1 month,3 months,6 months and 1 year after operation,with a significant difference among various time points (F=13.73,P =0.00).However,no significant difference was seen in the mean defect of perimetry among the different time points (F=1.02,P=0.41).The cup area (CA),cup/disc area ratio (C/DAR),cup volume (CV),mean cup depth (MCD),cup shape measurement (CSM),horizontal C/D,vertical C/D,rim area (RA),rim/disc area ratio (R/DAR),height variation contour (HVC),rim volume (RV),mRNFLT,RNFL cross sectional area (RNFLA) were gradually improved after operation in comparison with before operation.One year after operation,RV,CSM,mRNFLT,RNFLA were still increased,but vertical C/D was reduced after operation than that of before (P＜0.05).No significant differences were found in the whole mRNFLT and superior quadrant mRNFLT,inferior quadrant mRNFLT,nasal quadrant mRNFLT and temporal quadrant mRNFLT among before and after operation (F=1.63,P=0.16; F=0.51,P=0.77; F=1.44,P=0.20;F=1.02,P=0.32; F=1.31,P=0.30).Positive correlations were found between lowing-IOP range and the improvement of RV,CSM,vertical C/D (r =0.45,P =0.02; r=0.41,P=0.04; r=0.58,P=0.00),and negative correlations were seen between absolute value of MD and the improvement of RV,CSM 1 year after operation (r=-0.43,P=0.03; r=-0.62,P=0.00).Conclusions Reduction of IOP after trabeculectomy results in the reversal of optic disc parameters.The improvement of the optic disc parameters may be a protective factor for progression of glaucomatous optical nerve damage. Key words: Trabeculectomy; Glaucoma; Bio-measurement; Optic nerve head; Retinal nerve fiber layer

Comparison of Optic Disc Topography in the Cases With Graves Disease and Healthy Controls

To compare the optic nerve head topographic parameters of the cases with Graves disease (GD), and the age and sex-matched control group, by using Heidelberg retinal tomography III. We evaluated both eyes of 65 patients with GD and 54 age and sex-matched controls. For statistical analysis, Mann-Whitney U test and independent sample t test were used. Statistical significance was set as P < 0.05. The study group consisted of 22 male (33.8%) and 43 female (66.2%) GD cases with a mean age of 40.3 ± 11.9 years and the control group consisted of 26 male (48.1%) and 28 female (51.9%) healthy controls with a mean age of 36.9 ± 7.6 years. The differences between the age and sexes of the groups were not statistically significant (P = 0.07 and P = 0.11, respectively). The mean intraocular pressure of the study group was 14.6 ± 2.9 mm Hg (range, 8 to 20 mm Hg), whereas in the control group, it was 13.4 ± 2.1 mm Hg (range, 10 to 19 mm Hg). The difference between the intraocular pressures was statistically significant (P = 0.01). The mean retinal nerve fiber layer (RNFL) thickness (0.31 ± 0.08 mm) and the mean RNFL cross-sectional area (1.5 ± 0.43 mm) of the control group were greater than the mean RNFL thickness (0.25 ± 0.06 mm) and the mean RNFL cross-sectional area (1.30 ± 0.32 mm) of the study group (P = 0.02, P = 0.03 respectively). This result suggests that patients with GD may have thinner RNFL than healthy controls.

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.

The influence of surgical and medical interventions upon optic disc structure in patients with primary open angle glaucoma.

To evaluate the changes of optic disc parameters in primary open angle glaucoma (POAG) patients after surgical and medical treatment, and analyze the determinants of these changes. A total of 67 patients were enrolled in this study. Thirty nine patients (40 eyes) underwent trabeculectomy and 28 patients (32 eyes) received intra-ocular pressure (IOP) lowering medical therapy. All subjects underwent bilateral routine ocular examination and Heidelberg retina tomography (HRT) before treatment and 2 weeks, 1 month, 3 months, 6 months and 1 year after treatment. Changes in optic disc parameters in both the surgical and medical groups were analyzed, as was the influence of disease severity and IOP reduction on these changes. In the surgical group, the average preoperative IOP was 32.8±8.64 mmHg, which showed a significant decline at each post-operative visit. Most optic disc parameters measured by HRT were significantly improved after trabeculectomy (P=0.001~0.01), though the amount of improvement declined gradually during the post-operative period. Rim volume (RV), cup shape measure (CSM ), mean RNFL (mRNFL), RNFL cross sectional area (RNFLA) and vertical cup-to-disc ratio (C/D) still remained significantly below the pre-operative mean one year after surgery. In the medical group, the mean IOP before treatment was 24.8±4.32 mmHg and remained <21 mmHg on all subsequent post-treatment visits. However, no significant changes in optic disc parameters were found after initiation of medical treatment (F=0.52~2.21, P=0.75~0.07). In the surgical group, the extent of reduction of IOP was positively correlated with the improvement in RV, CSM and vertical C/D (r=0.41~0.58, P=0.001~0.04) at one year after trabeculectomy. The absolute value of the mean deviation on visual field testing was negatively correlated with the improvement of RV and CSM (r=-0.43~-0.62, P=0.03~0.001). Improvement in optic disc parameters occurred more commonly after surgical than medical treatment in POAG patients. The amount of reduction of IOP was correlated with the extent of this improvement, which may be more limited in more severe glaucoma.

Quantification of Optic Disc Edema during Exposure to High Altitude Shows No Correlation to Acute Mountain Sickness

BackgroundThe study aimed to quantify changes of the optic nerve head (ONH) during exposure to high altitude and to assess a correlation with acute mountain sickness (AMS). This work is related to the Tuebingen High Altitude Ophthalmology (THAO) study.Methodology/Principal FindingsA confocal scanning laser ophthalmoscope (cSLO, Heidelberg Retina Tomograph, HRT3®) was used to quantify changes at the ONH in 18 healthy participants before, during and after rapid ascent to high altitude (4559 m). Slitlamp biomicroscopy was used for clinical optic disc evaluation; AMS was assessed with Lake Louise (LL) and AMS-cerebral (AMS-c) scores; oxygen saturation (SpO2) and heart rate (HR) were monitored. These parameters were used to correlate with changes at the ONH. After the first night spent at high altitude, incidence of AMS was 55% and presence of clinical optic disc edema (ODE) 79%. Key stereometric parameters of the HRT3® used to describe ODE (mean retinal nerve fiber layer [RNFL] thickness, RNFL cross sectional area, optic disc rim volume and maximum contour elevation) changed significantly at high altitude compared to baseline (p<0.05) and were consistent with clinically described ODE. All changes were reversible in all participants after descent. There was no significant correlation between parameters of ODE and AMS, SpO2 or HR.Conclusions/SignificanceExposure to high altitude leads to reversible ODE in the majority of healthy subjects. However, these changes did not correlate with AMS or basic physiologic parameters such as SpO2 and HR. For the first time, a quantitative approach has been used to assess these changes during acute, non-acclimatized high altitude exposure. In conclusion, ODE presents a reaction of the body to high altitude exposure unrelated to AMS.

Retinal Nerve Fiber Layer Assessment: Area versus Thickness Measurements from Elliptical Scans Centered on the Optic Nerve

An evaluation of the retinal nerve fiber layer (RNFL) provides important information on the health of the optic nerve. Standard measurements of the RNFL consider only thickness, but an accurate assessment should also consider axial length, size of the optic nerve head (ONH), blood vessel contribution, and distance of the scan from the ONH margin. In addition, although most primate ONHs are elliptical, the circular scan centered on the ONH is the mainstay in both clinical and research analyses. The purpose of this study was to evaluate thickness and area measures of RNFL cross sections when axial length and ONH shape are included. Circular, raster, and radial scans of left eye optic nerves were acquired from 40 normal rhesus monkeys (Macaca mulatta) using spectral domain optical coherence tomography. The disc margin was identified by manually selecting the RPE/Bruch's membrane opening and ONH border tissue. With a pixel-to-micrometer conversion computed from a three-surface schematic eye, RNFL scans were interpolated at 300 to 600 μm (50-μm increments) from the edge of the ONH. The thickness and area of the RNFL at each distance were obtained by custom programs. Blood vessels in the RNFL were selected and removed from the overall RNFL measures. The average RNFL thickness decreased systematically from 149 ± 12.0 μm for scans 300 μm from the disc margin to 113 ± 7.2 μm at an eccentricity of 600 μm (P < 0.05). In contrast, the cross-sectional areas of the RNFL did not vary with scan location from the disc margin (0.85 ± 0.07 mm(2) at 300 μm compared with 0.86 ± 0.06 mm(2) at 600 μm). Blood vessels accounted for 9.3% of total RNFL thickness or area, but varied with retinal location. On average, 17.6% of the superior and 14.2% of the inferior RNFL was vascular, whereas blood vessels accounted for only 2.3% of areas of the temporal and nasal RNFL regions. In nonhuman primates, with appropriate transverse scaling and ONH shape analysis, the cross-sectional area of the RNFL is independent of scan distance, up to 600 μm from the rim margin, indicating that the axonal composition changes little over this range. The results suggest that, with incorporation of transverse scaling, the RNFL cross-sectional area, rather than RNFL thickness, provides an accurate assessment of the retinal ganglion cell axonal content within the eye.

Scanning laser ophthalmoscopic parameters of eyes with exfoliation syndrome

To evaluate optic nerve head (ONH) characteristics in patients with exfoliation syndrome (EXS). This was a cross-sectional, observational study in which 73 eyes from 73 patients with EXS and 93 eyes from 93 age-matched healthy subjects who met the inclusion criteria were included. Topographic measurements of the ONH and peripapillary retinal nerve fiber layer (RNFL) thickness were performed by confocal scanning laser ophthalmoscopy, using a Heidelberg retina tomograph. Outcomes of interest were studied by Student t test and chi-squared test. EXS patients and age-matched controls did not differ in ONH parameters. Nevertheless, the mean cup depth and height variation contour values were higher in the normal subjects (P = 0.07, P = 0.056, respectively). Mean RNFL thickness was 0.22 +/- 0.06 mm in the EXS group and 0.26 +/- 0.06 mm in the control group, (P = 0.001). Likewise, the RNFL cross-sectional area was significantly lower in exfoliative eyes (1.16 +/- 0.35 mm(2)) than in those of the control group (1.31 +/- 0.33 mm(2)) (P = 0.006). No significant differences in ONH parameters between EXS patients and age-matched healthy subjects were observed; however, RNFL measurements in eyes with EXS showed lower values.

Relationship between Central Corneal Thickness and Parameters of Optic Nerve Head Topography in Healthy Subjects

To investigate the relationship between central corneal thickness (CCT) and topographic parameters of optic nerve head (ONH) in healthy eyes. Right eyes of 208 healthy subjects between 40 and 59 years of age with refractive error less than 1 D were enrolled in this cross-sectional study. Ultrasonic pachymeter was used to measure CCT, and the ONH parameters were obtained by using confocal scanning laser ophthalmoscope. Relationship of various topographic parameters to age and sex were also investigated. For statistical analysis Student t test, analysis of variance, Pearson and Spearman test, and partial correlation coefficients were used. Mean CCT of subjects was 540.71+/-35.53 micronm (462-621 micronm), and the mean disc area was 2.37+/- 0.44 mm2 (1.28-3.66 mm2). CCT showed negative correlations to disc area, rim area, rim volume, and retinal nerve fiber layer (RNFL) area. These correlations were found to be stronger in females. Negative correlations were demonstrated between age and the mean cup depth, maximum cup depth, RNFL thickness, and RNFL cross sectional area. Women had lesser rim volumes, but bigger cup to disk (C/D) area and linear C/D ratios compared to those of men. In addition to its effect in the accuracy of intraocular pressure measurements, CCT has a structural relationship with the ONH in healthy nonglaucomatous eyes. Therefore, its effect on disc area might be especially important to explain the structural strength of the ONH in the pathogenesis of glaucoma.

Correlación entre los índices globales de la perimetría automatizada convencional y los parámetros topográficos papilares (Heidelberg Retina Tomograph II)

To correlate the optic nerve head topographic parameters measured by the Heidelberg Retina Tomograph II (HRT) with the perimetric indices of standard automated perimetry (SAP). This study included 101 normal subjects, 247 ocular hypertensive eyes (increased intraocular pressure with normal SAP) and 102 glaucomatous subjects (IOP above 21 mm Hg and abnormal standard automated perimetry). Only one eye was randomly chosen from each subject for the study. The visual field was evaluated by means of Humphrey Field Analyzer (24-2 full threshold strategy). The HRT II (Heidelberg Engineering) was used to acquire and measure the optic disc topographic parameters. Pearson correlations between topographic data and perimetric indices were performed for the total sample and each group of patients. The distribution of values obtained in the samples was normal. A significant correlation was found between several optic disc parameters and the global indices of SAP. Rim area, rim volume, cup/disc area ratio, rim/disc area ratio, cup shape measurement, RNFL cross-sectional area, and discriminant functions FSM and RB, showed the strongest correlation with the visual field indices in the total and glaucoma groups (RIM AREA: total group: r=0.32; p=4.14x10(-11)/glaucoma group: r=0.28; p=0.004. RIM VOLUME: total group: r=0.26; p=1.55x10(-7)/glaucoma group: r=0.26; p=0.006). The ocular hypertensive group showed few significant correlations. The correlations found between standard automated perimetry and HRT defined topographic parameters allow a better understanding of glaucomatous damage and make decision-making easier.

Scanning Laser Polarimetry and Retinal Thickness Analysis before and after Laser in Situ Keratomileusis

Purpose To evaluate changes in retinal nerve fiber layer (RNFL) thickness after laserin situ keratomileusis (LASIK) using a scanning laser Polarimeter with fixed corneal compensation (GDx) and the retinal thickness analyzer (RIA). Methods Thirty-eight eyes of 19 healthy subjects (10 female and 9 male; mean age 37.0±8.8 years) underwent GDx and RTA measurements before and after LASIK. All subjects revealed mild to high myopia (mean spherical refraction: −4.0±2.75 D). Measurements using GDx were followed by RTA measurements after pupil dilation. All measurements were performed the day before LASIK and 1 week postoperatively. Results GDX revealed a decrease in nerve fiber layer thickness measurements after LASIK, but did not reach statistical significance (p&gt;0.05). Using RTA, mean RNFL thickness (MRNFL) and RNFL cross sectional area decreased significantly after LASIK (p=0.03 and p=0.02, respectively). Conclusions Scanning laser polarimetry revealed a slight decrease in RNFL thickness measurements after LASIK. MRNFL and RNFL cross section were significantly lower after LASIK using RTA. The changes might be artifacts in a small group of myopic subjects.

Scanning laser polarimetry and retinal thickness analysis before and after laser in situ keratomileusis.

To evaluate changes in retinal nerve fiber layer (RNFL) thickness after laser in situ keratomileusis (LASIK) using a scanning laser polarimeter with fixed corneal compensation (GDx) and the retinal thickness analyzer (RTA). Thirty-eight eyes of 19 healthy subjects (10 female and 9 male; mean age 37.0-/+8.8 years) underwent GDx and RTA measurements before and after LASIK. All subjects revealed mild to high myopia (mean spherical refraction: -4.0-/+2.75 D). Measurements using GDx were followed by RTA measurements after pupil dilation. All measurements were performed the day before LASIK and 1 week postoperatively. GDx revealed a decrease in nerve fiber layer thickness measurements after LASIK, but did not reach statistical significance (p>0.05). Using RTA, mean RNFL thickness (MRNFL) and RNFL cross sectional area decreased significantly after LASIK (p=0.03 and p=0.02, respectively). Scanning laser polarimetry revealed a slight decrease in RNFL thickness measurements after LASIK. MRNFL and RNFL cross section were significantly lower after LASIK using RTA. The changes might be artifacts in a small group of myopic subjects.

Confocal Scanning Laser Ophthalmoscopy of Eyes with Nonarteritic Anterior Ischemic Optic Neuropathy

Purpose: To evaluate optic nerve head topography in patients with nonarteritic anterior ischemic optic neuropathy (NAION) using confocal scanning laser ophthalmoscopy. Methods: Both eyes of patients with NAION were imaged using a Heidelberg retina tomograph (HRT II; version 1.5) several months after initial presentation, when the optic disc edema had settled. Data from the stereometric analysis of optic nerve heads of eyes with NAION were compared to those of fellow eyes without NAION and eyes of an age- and sex-matched control group. Stereometric parameter values of the fellow eyes were compared with those of the control group. Results: Average age of the 23 Caucasian patients was 57.96 ± 10.41 years (range: 28–71 years). Seven patients (30%) were female and 16 (70%) were male. Four patients (17%) had bilateral NAION. Cup area, cup volume, cup/disc area, linear cup/disc area, mean cup depth, maximum cup depth, mean retinal nerve fiber layer (RNFL) thickness, and RNFL cross-sectional area values were smaller in the NAION eyes than in the control eyes (p < 0.05). A comparison of the NAION eyes with their fellow eyes revealed lower mean cup depth, maximum cup depth, mean RNFL thickness, and RNFL cross-sectional area in the diseased eyes (p < 0.05). Moreover, cup area, cup volume, cup/disc area, linear cup/disc area, mean cup depth, maximum cup depth values were smaller in the fellow eyes than the control eyes (p < 0.05). Conclusion: Using an objective imaging method, confocal scanning laser ophthalmoscopy, eyes with NAION were shown to have a smaller cup volume and cup/disc area, but not a smaller optic disc area than control eyes.

Assessment of optic nerve head topographic parameters with a confocal scanning laser ophthalmoscope.

To assess the disc area, age, sex, laterality (side of the eyes) and refractive error dependent differences in optic nerve head topographic parameters in a normal population. Optic nerve head topographic analysis of both eyes of 551 healthy Turkish subjects aged 11-75 years (1102 eyes) was performed using a confocal scanning laser ophthalmoscope, the Heidelberg Retinal Tomograph II (HRT II). The effects of disc size, sex, laterality (side of the eyes), age and refractive error on optic nerve head topographic parameters were assessed. Subjects were divided into three different age groups (<30 years, 30-60 years, >60 years) and three different disc area groups (<2.00 mm(2), 2.00-2.25 mm(2), >2.25 mm(2)). Disc area, topography standard deviation and a total of 12 topographic parameters were calculated by HRT II for each subject. Statistical analysis was performed using Student's t-test, multiple regression analysis, Tukey-HSD test, anova and Pearson's correlation coefficient. A total of 543 subjects (298 women and 245 men) were included in the study. The mean disc area of the subjects was 2.12 +/- 0.47 mm(2) (range 1.16-4.98 mm(2)). The mean refractive error of the subjects was -0.58 +/- 1.71 D (range -4.75 D to +4.25 D). The mean cup shape measure was -0.21 +/- 0.07 (95% confidence interval -0.07 to -0.35). The disc area was significantly correlated with all of the topographic parameters but two; namely, the cup shape measure and the height variation contour. Significant age-related differences were detected in four parameters (mean retinal nerve fibre layer [RNFL] thickness, disc area, cup-to-disc area ratio, cup area) and significant sex-related differences were detected three parameters (mean RNFL thickness, height variation contour, RNFL cross-sectional area). However, there were no significant differences in any of the parameters for laterality and refractive error. The parameter cup shape measure did not correlate with any of the five variables investigated. Cup shape measure was the only optic nerve head topographic parameter that was independent of age, sex, disc area, laterality and the refractive error. It seems to be a promising parameter in evaluation and comparison of the optic discs of normal subjects, with different disc area, age, sex, refraction error and laterality, as being independent of the main variation factors of the disc topography.

Heidelberg retina tomograph in ocular Behçet's disease.

To compare the optic disc topography of patients with ocular Behçet's disease (BD) with age-matched controls, using Heidelberg retina tomograph (HRT). This study included 32 patients (51 eyes) with ocular BD (active and/or inactive), 38 patients (74 eyes) with nonocular BD, and 62 normal subjects (62 eyes). All patients and control group underwent complete ophthalmologic evaluation. Intraocular pressure was less than 22 mmHg in patients and in the control group. The optic nerve heads of all subjects were imaged with the HRT (software 2.01a-M). The following stereometric parameters were calculated for each patient: disc area, cup area, cup/disc area ratio, rim area, height variation contour, cup volume, rim volume, mean cup depth, cup shape measure, mean RNFL thickness, and RNFL cross-sectional area. Differences among the groups were evaluated by Kruskal-Wallis variance analysis. When the Kruskal-Wallis test revealed a significant difference between groups, multiple comparison tests were used to find out which groups differed from which others. The mean disc area was significantly smaller (P<0.05) in patients with ocular and nonocular BD. The mean cup area, mean cup depth, and mean cup volume were significantly smaller (P<0.05) in patients with ocular BD. No significant differences were found between the groups in terms of the other stereometric parameters (P>0.05). A small disc and cup may be an additional risk factor for retinal vaso-occlusion in ocular Behçet's disease.