Variation In Retinal Thickness Research Articles

Postoperative Proliferation Detection in Eyes Treated for Rhegmatogenous Retinal Detachment by WideField OCT Angiography.

Proliferative retinal changes may occur postsurgery for rhegmatogenous retinal detachment (RRD), possibly preceding recurrent detachment. This study aims to establish the groundwork for an imaging system capable of discerning changes in retinal vessel tortuosity after RRD repair, analyzing widefield optical coherence tomography angiography (WF-OCTA) images. Eighty-eight eyes of 86 patients with RRD who underwent surgical procedures and had repeated imaging with clear widefield optical coherence tomography (WF-OCT) and WF-OCTA on different postoperative days were enrolled in this retrospective study. We compared WF-OCTA images over time to identify alterations in retinal vessel tortuosity and observed regional changes in retinal morphology. After image processing, changes in retinal vessel tortuosity were detected in 66 quadrants. These changes, attributed to retinal traction from proliferative membranes, were observed in 56 quadrants, among which retinal thickness remained unchanged in seven sectors (12.5%) according to the WF-OCT map. In nine quadrants, changes in retinal vessel tortuosity were attributed to changes in subretinal fluid, aligning with observable variations in retinal thickness. Observation of vessel tortuosity changes using WF-OCTA can help detect early postoperative proliferative changes in eyes with RRD. Because WF-OCTA can detect minute vessel tortuosity changes, it can offer a noninvasive alternative for the detection of early postoperative proliferative changes.

Derivation of human retinal cell densities using high-density, spatially localized optical coherence tomography data from the human retina.

This study sought to identify demographic variations in retinal thickness measurements from optical coherence tomography (OCT), to enable the calculation of cell density parameters across the neural layers of the healthy human macula. From macular OCTs (n=247), ganglion cell (GCL), inner nuclear (INL), and inner segment-outer segment (ISOS) layer measurements were extracted using a customized high-density grid. Variations with age, sex, ethnicity, and refractive error were assessed with multiple linear regression analyses, with age-related distributions further assessed using hierarchical cluster analysis and regression models. Models were tested on a naïve healthy cohort (n=40) with Mann-Whitney tests to determine generalizability. Quantitative cell density data were calculated from histological data from previous human studies. Eccentricity-dependent variations in OCT retinal thickness closely resemble topographic cell density maps from human histological studies. Age was consistently identified as significantly impacting retinal thickness (p=.0006, .0007, and .003 for GCL, INL and ISOS), with gender affecting ISOS only (p<.0001). Regression models demonstrated that age-related changes in the GCL and INL begin in the 30th decade and were linear for the ISOS. Model testing revealed significant differences in INL and ISOS thickness (p=.0008 and .0001; however, differences fell within the OCT's axial resolution. Qualitative comparisons show close alignment between OCT and histological cell densities when using unique, high-resolution OCT data, and correction for demographics-related variability. Overall, this study describes a process to calculate in vivo cell density from OCT for all neural layers of the human retina, providing a framework for basic science and clinical investigations.

ABOUT A POSSIBILITY OF PREDICTING THE CONTRAST SENSITIVITY THROUGH INTENSE PHYSICAL EFFORT IN DIABETIC RETINOPATHY

The present work makes a comparison between the sensitivity to contrast in the case of people with and without diabetic retinopathy, but who perform physical effort or not by walking alertly in the Nordic style. The differences between the two types of state, at rest or systematic movement, were extrapolated, in order to predict the evolution of this quality of human vision. The objective pursued consisted in obtaining relevant arguments for the promotion of current health strategies through sports. The psychophysical tests used to determine contrast sensitivity were supplemented with those which determine the variation in retinal thickness measured by computerized optical tomography

Effects of Monocular Light Deprivation on the Diurnal Rhythms in Retinal and Choroidal Thickness

PurposeTo determine the effects of monocular light deprivation on diurnal rhythms in retinal and choroidal thickness.MethodsTwenty participants, ages 22 to 45 years, underwent spectral domain optical coherence tomography imaging every three hours, from 8 AM to 8 PM, on two consecutive days. Participants wore an eye patch over the left eye starting at bedtime of day 1 until the end of the last measurement on day 2. Choroidal, total retinal, photoreceptor outer segment + retinal pigment epithelium (RPE), and photoreceptor inner segment thicknesses were determined.ResultsFor both eyes, significant diurnal variations were observed in choroidal, total retinal, outer segment + RPE, and inner segment thickness (P < 0.001). For light-deprived eyes, choroid diurnal variation persisted, although the choroid was significantly thinner at 8 AM and 11 AM (P < 0.01) on day 2 compared to day 1. On the other hand, diurnal variations in retinal thickness were eliminated in the light-deprived eye on day 2 when the eye was patched (P > 0.05). Total retinal and inner segment thicknesses significantly decreased (P < 0.001) and outer segment + RPE thickness significantly increased (P < 0.05) on day 2 compared to day 1.ConclusionsBlocking light exposure in one eye abolished the rhythms in retinal thickness, but not in choroidal thickness, of the deprived eye. Findings suggest that the rhythms in retinal thickness are, at least in part, driven by light exposure, whereas the rhythm in choroidal thickness is not impacted by short-term light deprivation.

Association between retinal thickness variation and visual acuity change in neovascular age-related macular degeneration.

To assess the association between variation in retinal central subfield thickness (CSFT) with best-corrected visual acuity (BCVA) change in patients receiving vascular endothelial growth factor (VEGF) inhibitor therapy for neovascular age-related macular degeneration (nAMD). CSFT measurements were obtained from 141 eyes (total 1300 scans). SD of CSFT was calculated. The eyes were categorised into CSFT variation tertiles. Multiple linear regression was used to examine the association between the CSFT tertiles and BCVA change at 12 mo, adjusting for differences in baseline demographic and clinical characteristics. At 12 mo, the mean BCVA of the high CSFT variation group (50.6 letters) was significantly lower than the low and moderate CSFT variation groups (57.5 and 59.8 letters, respectively), P=.02. The adjusted mean BCVA gains were +1.7, +7.2, and +7.8 letters in the high, moderate and low CSFT variation groups, respectively (P=.03). A greater variation in retinal thickness during VEGF inhibitor therapy for nAMD is associated with a less favourable visual outcome. CSFT stability is useful in prognosticating visual outcomes in VEGF inhibitor therapy for nAMD.

RETINAL FLUID AND THICKNESS AS MEASURES OF DISEASE ACTIVITY IN NEOVASCULAR AGE-RELATED MACULAR DEGENERATION.

Retinal fluid and thickness are important anatomical features of disease activity in neovascular age-related macular degeneration, as evidenced by clinical trials that have used these features for inclusion criteria, retreatment criteria, and outcome measures of the efficacy of intravitreal injections of anti-vascular endothelial growth factor agents. A literature review of anatomical measures of disease activity was conducted. Treatment goals for neovascular age-related macular degeneration include improving/maintaining vision by drying the retina, and several analyses have evaluated the relationship between visual function and anatomy. The change in retinal thickness has been found to correlate with the change in the visual acuity, and variation in retinal thickness may predict visual acuity outcomes. In addition, specific fluid compartments may have different prognostic values. For example, the presence of intraretinal fluid has been associated with poorer visual acuity, whereas the presence of subretinal fluid has been associated with better visual acuity. Retinal fluid and thickness are important for selecting dosing interval durations in clinical trials and clinical practice. Retinal thickness and retinal fluid are common anatomical measures of disease activity in neovascular age-related macular degeneration. Further research is required to fully elucidate the relationship between anatomical features and visual outcomes in neovascular age-related macular degeneration.

The Influence of Axial Length Upon the Retinal Ganglion Cell Layer of the Human Eye.

PurposeVariation in retinal thickness with eye size complicates efforts to estimate retinal ganglion cell number from optical coherence tomography (OCT) measures. We examined the relationship among axial length, the thickness and volume of the ganglion cell layer (GCL), and the size of the optic chiasm.MethodsWe used OCT to measure GCL thickness over 50 degrees of the horizontal meridian in 50 healthy participants with a wide range of axial lengths. Using a model eye informed by individual biometry, we converted GCL thickness to tissue volume per square degree. We also measured the volume of the optic chiasm for 40 participants using magnetic resonance imaging (MRI).ResultsThere is a positive relationship between GCL tissue volume and axial length. Given prior psychophysical results, we conclude that increased axial length is associated with increased retinal ganglion cell size, decreased cell packing, or both. We characterize how retinal ganglion cell tissue varies systematically in volume and spatial distribution as a function of axial length. This model allows us to remove the effect of axial length from individual difference measures of GCL volume. We find that variation in this adjusted GCL volume correlates well with the size of the optic chiasm.ConclusionsOur results provide the volume of ganglion cell tissue in the retina, adjusted for the presumed effects of axial length upon ganglion cell size and/or packing. The resulting volume measure accounts for individual differences in the size of the optic chiasm, supporting its use to characterize the post-retinal visual pathway.Translational RelevanceVariations in ametropia can confound clinical measures of retinal features. We present a framework within which the thickness and volume of retinal structures can be measured and corrected for the effects of axial length.

Associations of Variation in Retinal Thickness With Visual Acuity and Anatomic Outcomes in Eyes With Neovascular Age-Related Macular Degeneration Lesions Treated With Anti–Vascular Endothelial Growth Factor Agents

When initiating anti-vascular endothelial growth factor (VEGF) treatment for patients with neovascular age-related macular degeneration (nAMD), knowledge of prognostic factors is important for advising patients and guiding treatment. We hypothesized that eyes with greater fluctuation in retinal thickness over time have worse outcomes than eyes with less variation. To investigate whether visual and anatomic outcomes in eyes with nAMD initiating anti-VEGF treatment are associated with fluctuations in retinal thickness. In this study using data from the Comparison of Age-Related Macular Degeneration Treatments Trials (CATT) and the Inhibition of VEGF in Age-Related Choroidal Neovascularization (IVAN) randomized clinical trial, people with previously untreated nAMD were included. Data were collected from February 2008 to November 2012, and data were analyzed from April 2017 to April 2020. Foveal center point thicknesses (FCPTs) were extracted from 1165 study eyes from CATT and 566 study eyes from the IVAN trial, excluding those with 3 measurements or less. For each eye, the SD of FCPT was calculated. Eyes were grouped by FCPT SD quartile. Associations of FCPT SD quartile with outcomes were quantified at month 24 or the last available visit by linear or logistic regression, adjusting for baseline best-corrected visual acuity (BCVA) and randomized allocations to drug and treatment regimen, for BCVA, development of fibrosis, and development of macular atrophy. Of the 1731 included patients, 1058 (61.1%) were female, and the mean (SD) age was 78.6 (7.4) years. The median (interquartile range) FCPT SD was 40.2 (27.1-61.2) in the IVAN cohort and 59.0 (38.3-89.4) in the CATT cohort. After adjustment for baseline BCVA and trial allocations, BCVA worsened significantly across the quartiles of FCPT SD; the difference between the first and fourth quartiles was -6.27 Early Treatment Diabetic Retinopathy Study letters (95% CI, -8.45 to -4.09). The risk of developing fibrosis and macular atrophy also increased across FCPT SD quartiles. Odds ratios ranged from 1.40 (95% CI, 1.03 to 1.91) for quartile 2 to 1.95 (95% CI, 1.42 to 2.68) for quartile 4 for fibrosis and from 1.32 (95% CI, 0.90 to 1.92) for quartile 2 to 2.10 (95% CI, 1.45 to 3.05) for quartile 4 for macular atrophy. Greater variation in retinal thickness in eyes with nAMD during treatment with anti-VEGF was associated with worse BCVA and development of fibrosis and macular atrophy in these post hoc analyses, despite protocol-directed treatment frequency. Practitioners may want to consider variation in retinal thickness when advising patients about their prognosis.

Wide-field individual retinal layer thickness in healthy eyes.

To report the individual retinal layer thickness in healthy subjects using wide-field optical coherence tomography. This was a prospective, cross-sectional study involving healthy subjects. A custom-designed semiautomated segmentation algorithm was used to split the retinal layers in seven bands, and individual retinal layer thicknesses were measured in horizontal (nasal, macular, and temporal segments) and vertical meridians (superior, macular, and inferior segments). The variation in retinal thickness was analyzed in different segments at an interval of 1 mm from reference points. Regression analysis was performed to identify the factors affecting retinal thickness. Twenty eyes of 20 healthy subjects with mean age of 28.9 ± 6.3years were analyzed. Overall, nasal and superior segments (mean ± standard deviation: 279.6 ± 17.0 and 234.4 ± 19.2 µm) had maximum and minimum retinal thicknesses, respectively. A total of seven bands were delineated in each optical coherence tomography b scan in each segment. Retinal nerve fiber layer was thickest immediately nasal to optic disk margin in horizontal scan (72.4 ± 32.4 µm) and near the vascular arcades in vertical meridian. Outer plexiform layer, external limiting membrane-ellipsoid zone and interdigitation zone-retinal pigment epithelium-Bruch's complex showed significant variation in both horizontal and vertical meridians (all p values <0.05). Macular segment in both meridians showed the highest coefficient of variation. Age was the only significant factor affecting retinal thickness in multiple regression analysis (p = 0.001). Wide-field optical coherence tomography shows significant regional variation in overall and individual retinal layer thicknesses in macular and peripheral areas in healthy eyes with the highest variation in macular segment.

Myopia and Regional Variations in Retinal Thickness in Healthy Eyes.

Purpose To investigate the effects of refraction on retinal thickness measurements at different locations and layers in healthy eyes of Saudi participants.MethodsThirty-six randomly selected adults aged 27.0 5.7 years who attended a Riyadh hospital from 2016 to 2017 were categorized into three groups: non-myopic (spherical equivalent refraction [SER], +1.00 to –0.50 diopters [D]), low myopic (SER, –0.75 to –3.00D), and moderate to high myopic (SER –3.25D). Full, inner, and outer retinal thicknesses were measured at nine locations by spectral-domain stratus optical coherence tomography (Optovue Inc., Fremont, CA, USA) and were compared according to refractive group and sex.ResultsThe mean SERs for the non-myopia, low myopia, and moderate to high myopia groups were 0.2 0.6, –1.5 0.5, and –7.5 1.9 D, respectively. Refractive error, but not sex, had significant effects on the retinal layer thickness measurements at different locations (P 0.05). The parafoveal and outer retinal layers were significantly thicker than the perifoveal and inner retina layers in all groups (P 0.05). The full foveal thickness was higher and the full parafoveal and perifoveal regions were thinner in moderate to high myopic eyes than in the non-myopic eyes (P 0.05), but were similar to those in the low myopic eyes (P 0.05). The foveal thicknesses measured in the inner and outer layers of the retina were higher but the thicknesses measured at the inner and outer layers of the parafoveal and perifoveal regions were lower in moderate to high myopic eyes.Conclusion There were regional differences in the retinal layer thicknesses of healthy Saudi eyes, which was dependent on the central refractions. This is important when interpreting retinal nerve fiber layer thicknesses in myopia and disease management in Saudi participants.

Normative Retinal Thicknesses in Common Animal Models of Eye Disease Using Spectral Domain Optical Coherence Tomography.

Purpose This study demonstrates a standardized approach to measuring retinal thickness (RT) using spectral domain optical coherence tomography (SD-OCT) in commonly used animal models of disease and reports a normative data set for future use. Materials and Methods Twenty normal eyes of 4 adult animal models (5 rats, 5 rabbits, 5 canines, and 5 mini-pigs) were used. Manual measurements were made on the commercially available Heidelberg Spectralis™ SD-OCT to determine the total, inner, and outer retinal thickness (RT) at fixed distances from the optic nerve head (ONH) (1, 2, 3, 4, 5, and 6 mm away) in order to control for normal variation in retinal thickness. Analysis of variance (ANOVA) with P value <0.05 indicated statistical significance. Results Total RT significantly decreased with increasing distance from the ONH for the canine, mini-pig, and rabbit vascular models. Inner RT significantly decreased for the canine, mini-pig, rabbit vascular, and rabbit avascular models; and outer RT significantly decreased for only the canine model. Among the animal models, RT at similar distances from the ONH were significantly different for total, inner, and outer RT. Conclusion There are significant differences in the total, inner, and outer RT of normal canine, mini-pig, rabbit, and rat retinas with SD-OCT using a standardized approach. These measurements provide a normative reference for future studies and illustrate a standardized method of assessing RT.

Effects of age and gender on macular thickness in healthy subjects using spectral optical coherence tomography/scanning laser ophthalmoscopy.

To examine healthy subjects for normal macular thickness values and determine the effects of gender and age in a Turkish population, using spectral optical coherence tomography/scanning laser ophthalmoscopy (OCT/SLO). Six hundred fourteen eyes of 307 subjects with no history of ocular diseases and normal ophthalmic examination were recruited in this cross-sectional, prospective study. The participants were divided into three groups based on age (between 20 and 29years: group 1, between 30 and 39years: group 2, between 40 and 49years: group 3). All subjects were scanned with spectral OCT/SLO, performed by one examiner to acquire the retinal thickness map in the ETDRS grid, and values were recorded for nine sectors, and effects of age and gender were evaluated. When all the subjects were evaluated, the thicknesses were lower in women than men in all sectors (p<0.001). When divided in groups based on age, this difference remained only in the outer segments. However, the differences in outer layers, except outer nasal layer, were thicker in women in group 3 when compared to others in group 3. When compared between groups, only central thickness in group 3 was shown to be higher than group 1 (p=0.06). There was no significant difference of thicknesses in any sector when compared right and left eyes of all subjects. The study reports the variation in retinal thickness between age and gender in a relatively large sample of a Turkish population. It is important to consider these effects while interpreting the OCT images to make an appropriate diagnosis in retinal diseases.

Retinal thickness in black and Indian myopic students at the University of KwaZulu-Natal

Background: It has been suggested that retinal thickness varies with demographic variables. Understanding the influence of demographic variables on retinal thickness could improve our knowledge of risk factors for retinal pathologies. Previous studies have focused exclusively on white and African-American populations, with limited attention to black and Indian populations.Aim: To compare retinal thickness in black and Indian myopic students at the University of KwaZulu-Natal (UKZN).Methods: A cross-sectional comparative research design was used. The study was conducted at UKZN, Westville campus. Retinal thickness was measured in 80 healthy myopic students using the Fourier/spectral domain iVue 100 optical coherence tomographer. Retinal thickness measurements of the right and left eyes showed significant correlations, therefore data from only the right eyes were analysed. Racial and gender variations in retinal thickness of the nine Early Treatment Diabetic Retinopathy Study (ETDRS) segments were assessed.Results: The mean central foveal thickness in black participants was 238 μm compared with 243 μm in Indian participants (p = 0.06). Indian participants had thicker parafoveal thickness measurements whilst black participants had thicker perifoveal thickness measurements. Male participants had thicker retinal thickness measurements in all nine ETDRS segments than female participants. Central foveal thickness showed no significant correlation with spherical equivalent (r = -0.14, p &gt; 0.05) or axial length (r = 0.09, p &gt; 0.05).Conclusion: The average central foveal thickness was slightly thinner in black and female participants than in Indian and male participants. Optometrists and ophthalmologists should consider these differences when evaluating black and Indian individuals with foveal retinal diseases.

Accommodation-induced variations in retinal thickness measured by spectral domain optical coherence tomography.

To research retinal stretching or distortion with accommodation, accommodation-induced changes in retinal thickness (RT) in the macular area were investigated in a population of young adults (n = 23) by using a dual-channel spectral domain optical coherence tomography (SD-OCT) system manufactured in-house for this study. This dual-channel SD-OCT is capable of imaging the cornea and retina simultaneously with an imaging speed of 24 kHz A-line scan rate, which can provide the anatomical dimensions of the eye, including the RT and axial length. Thus, the modification of the RT with accommodation can be calculated. A significant decrease in the RT (13.50 ± 1.25 μm) was observed during maximum accommodation. In the 4 mm × 4 mm macular area centered at the fovea, we did not find a significant quadrant-dependent difference in retinal volume change, which indicates that neither retinal stretching nor distortion was quadrant-dependent during accommodation. We speculate that the changes in RT with maximum accommodation resulted from accommodation-induced ciliary muscle contractions.

24-Hour variation of optical coherence tomography–measured retinal thickness in diabetic macular edema

To investigate 24-hour variation in retinal thickness in patients with diabetic macular edema (DME) using optical coherence tomography (OCT). Fifty-three eyes of 53 diabetic patients with clinically significant macular edema and central subfield thickness (CST) >225 µm, 36 eyes of 36 healthy individuals (normal controls), and 22 eyes of 22 diabetic patients without macular pathology (diabetic controls) underwent 5 OCT measurements at 7 am, 10 am, 3 pm, 8 pm, and 1 am. Visual acuity, blood pressure, blood glucose, and body temperature were measured as well. The CST (p<0.0005), total macular volume (p<0.0005), and visual acuity (p<0.0005) showed significant variation in patients. The CST (450 µm at 7 am) reached a minimum at 3 pm (absolute change of -49 µm, relative change of -17%) before increasing again. Thickening changes were higher in more thickened retinas (p<0.0005, p=0.024, absolute and relative change, respectively). Visual acuity was worse in the morning (0.38 logMAR) and improved to a maximum at 8 pm (0.30 logMAR) (p<0.0005). Blood pressure, blood glucose, and body temperature did not vary over time. The 24-hour variation of retinal thickness is observed in a large proportion of patients with DME, with a decrease from morning to afternoon. Time of examination should be taken into account when managing such patients.

Author Response: Diurnal Variation of Retinal Thickness Measured by Optical Coherence Tomography in Normal Adults

Author Response: Diurnal Variation of Retinal Thickness Measured by Optical Coherence Tomography in Normal Adults

Retinal Thickness Analysis by Race, Gender, and Age Using Stratus OCT

To detect differences in retinal thickness among patients of different race, gender, and age using Stratus OCT. Cross-sectional study. In a multicenter, university-based study, 126 patients with no history of ocular disease were enrolled (78 diabetics without retinopathy and 48 nondiabetics). Optical coherence tomography measurements were performed using Stratus OCT. Statistical comparisons of center point foveal thickness and mean foveal thickness were made using generalized estimating equations adjusting for diabetic status, race, age, and gender. The study population consisted of 36% male subjects, 39% Caucasian, 33% African-American, and 28% Hispanic. Mean foveal thickness was 191.6 +/- 2.7 microm and 194.5 +/- 2.7 microm for diabetics and nondiabetics, respectively (P = .49). Mean foveal thickness in male subjects was significantly larger than in female (201.8 +/- 2.7 microm and 186.9 +/- 2.6 microm, respectively; P < .001). Mean foveal thickness was 200.2 +/- 2.7 microm for Caucasian, 181.0 +/- 3.7 microm for African-American, and 194.7 +/- 3.9 microm for Hispanic subjects. Mean foveal thickness was significantly less for African-American than Caucasian (P < .0001) or Hispanic subjects (P = .005). Center point foveal thickness and mean foveal thickness showed a significant increase with age. There are statistically significant differences in retinal thickness between subjects of different race, gender, and age. When compared to Caucasian and Hispanic subjects, African-American race is a predictor of decreased mean foveal thickness; and male sex (regardless of race) is a significant predictor of increased mean foveal thickness. Mean foveal thickness is similar among diabetics and nondiabetics when data are controlled for age, race, and sex. These results suggest that studies comparing OCT measurements should carefully control for age-based, race-based, and gender-based variations in retinal thickness.

Reproducibility of macular edema measurements using OCT 3 versus HRT II in neovascular AMD

PURPOSE: To assess reliability of optical coherence tomography (OCT) versus Heidelberg retinal topography (HRT) to record macular alterations without fluorescein angiography in neovascular AMD. METHODS: Forty patients with predominantly classic choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD) were examined by OCT, HRT macular module and fluorescein angiography (FA) before, and 6 and 12 weeks following PDT. The changes in retinal thickness in the macular area measured by OCT in 9 fields were compared to the changes in edema index obtained by HRT in corresponding 9 fields. Results were correlated with leakage determined by FA. RESULTS: Following treatment, changes in most OCT thickness values were statistically significant at both follow-ups. In contrast, only edema indices measured by HRT II following manual adjustment showed significant differences. Variations in retinal thickness measured by OCT did not correlate with changes in edema index determined by HRT in any of the 9 fields. The presence of leakage on FA showed no correlation with foveal thickness and edema index at any visit. CONCLUSIONS: The HRT II detected fewer changes in neovascular AMD then the OCT3, and may therefore be unreliable for post treatment monitoring. Due to lack of correlation, neither OCT nor HRT is able to replace the primary evaluation of therapeutic success in neovascular AMD by FA.

Tomographie par cohérence optique de type Spectral Domain dans la dégénérescence maculaire liée à l’âge: Premiers résultats avec Spectralis HRA-OCT®

Optical coherence tomography (OCT) imaging has become extremely valuable in demonstrating the presence of neurosensory or retinal pigment epithelial elevation or detachment associated with occult choroidal newvessels. This imaging method has recently been improved using the Fourier Transform and is called Spectral Domain-OCT or SD-OCT. The preliminary results using this imaging technique can now be used to analyze the advantages of the technique's sensitivity and acquisition speed.and methods: A consecutive series of 100 AMD patients was examined prospectively and followed with the Spectralis HRA-OCT device (Heidelberg Engineering, Heidelberg, Germany). Each patient underwent a complete ophthalmologic examination, including biomicroscopy, fluorescein and ICG angiographies, and OCT examinations.Different clinical forms of early AMD and advanced ARMD, either atrophic or exudative, can benefit from this new examination. The various changes were registered, mainly at the level of the outer nuclear layer, the outer limiting membrane, and the interface between the inner and outer segments. Intra- or subretinal fluid accumulation and the variations in retinal thickness were precisely analyzed and compared during follow-up using the Tomography Laser Tracking System.The Tomography Laser Tracking System can efficiently evaluate the results of treatment, correlated with the angiographic and functional data, providing great assistance in diagnosis and indications for treatment and retreatment. Quantitative measurements can be taken, not only in the lesion area, but also of their volume (especially for drusen), which may become useful in detecting complications in high-risk patients.

Polarization-sensitive spectral-domain optical coherence tomography using a single line scan camera

Polarization-sensitive optical coherence tomography can be used to measure the birefringence of biological tissue such as the human retina. Previous measurements with a time-domain polarization-sensitive optical coherence tomography system revealed that the birefringence of the human retinal nerve fiber layer is not constant, but varies as a function of location around the optic nerve head. Here we present a spectral-domain polarization-sensitive optical coherence tomography system that uses a spectrometer configuration with a single line scan camera and a Wollaston prism in the detection arm. Since only one camera has to be synchronized with other components in the system, the design is simplified considerably. This system is 60 times faster than a time-domain polarization-sensitive optical coherence tomography system. Data was acquired using concentric circular scans around the optic nerve head of a young healthy volunteer and the acquisition time for 12 circular scans was reduced from 72 s to 1.2 s. The acquired data sets demonstrate variations in retinal thickness and double pass phase retardation per unit depth that were similar to data from the same volunteer taken with a time-domain polarization-sensitive system. The double pass phase retardation per unit depth of the retinal nerve fiber layer varied between 0.18 and 0.40 degrees/mum, equivalent to a birefringence of 2.2 * 10(-4) and 4.8 * 10(-4) respectively, measured at 840 nm.