PURPOSE\nTo measure macular choroidal thickness in normal eyes at different points using enhanced depth imaging (EDI) optical coherence tomography (OCT) and to evaluate the association of choroidal thickness and age.\n\n\nDESIGN\nRetrospective, observational case series.\n\n\nMETHODS\nEDI OCT images were obtained in patients without significant retinal or choroidal pathologic features. The images were obtained by positioning a spectral-domain OCT device close enough to the eye to acquire an inverted image. Seven sections were obtained within a 5 x 30-degree area centered at the fovea, with 100 scans averaged for each section. The choroid was measured from the outer border of the retinal pigment epithelium to the inner scleral border at 500-microm intervals of a horizontal section from 3 mm temporal to the fovea to 3 mm nasal to the fovea. Statistical analysis was performed to evaluate variations of choroidal thickness at each location and to correlate choroidal thickness and patient age.\n\n\nRESULTS\nThe mean age of the 30 patients (54 eyes) was 50.4 years (range, 19 to 85 years), and 14 patients (46.7%) were female. The choroid was thickest underneath the fovea (mean, 287 microm; standard deviation, +/- 76 microm). Choroidal thickness decreased rapidly in the nasal direction and averaged 145 microm (+/- 57 microm) at 3 mm nasal to the fovea. Increasing age was correlated significantly with decreasing choroidal thickness at all points measured. Regression analysis suggested that the subfoveal choroidal thickness decreased by 15.6 microm for each decade of life.\n\n\nCONCLUSIONS\nChoroidal thickness seems to vary topographically within the posterior pole. The thickness of the choroid showed a negative correlation with age. The decrease in the thickness of the choroid may play a role in the pathophysiologic features of various age-related ocular conditions.

Enhanced Depth Imaging Optical Coherence Tomography of the Choroid in Normal Eyes

Mechanisms of age-related macular degeneration

The purpose of this evidence summary is to provide the best available information on the effect of anti-oxidants on mortality in patients with various diseases.

/pdf/antioxidant-supplements-for-prevention-of-mortality-in-4y5qa95qy1.pdf

Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases

https://serval.unil.ch/resource/serval:BIB_3A01220E0FF1.P001/REF.pdf

Central serous chorioretinopathy: Recent findings and new physiopathology hypothesis.

Optical coherence tomography angiography: A comprehensive review of current methods and clinical applications.

Central Serous Chorioretinopathy: Update on Pathophysiology and Treatment

Optical coherence tomography (OCT) evaluation of macular structure is important in the diagnosis and monitoring of patients with diabetic macular edema (DME). Automated measurements of retinal thickness and volume in the macula from retinal tomograms using image-processing software have been useful in observing patients longitudinally in clinical practice and making comparisons in clinical trials. To date, time domain OCT using the Stratus OCT (Carl Zeiss Meditec, Inc., Dublin, CA) has been the most widely used technique for obtaining macular measurements1-5 and has been shown in previous studies to generate measurements with high repeatability.6-9 This instrument acquires images at a rate of 400 axial scans per second, with an axial resolution of 10 μm. Recently, a new class of OCT instruments employing spectral (Fourier) domain technology has been developed. One such instrument that is currently commercially available is the Cirrus HD-OCT (Carl Zeiss Meditec, Inc.). Although both time domain and spectral domain OCT use the same basic working principles, the scan rate of spectral domain OCT is at least 20,000 axial scans per second, with an improved axial resolution of 5 μm.

Both the Stratus OCT and the Cirrus HD-OCT systems employ intrinsic software algorithms to calculate retinal thicknesses averaged across standardized subfields in the macula. Data for thickness calculations are collected from an array of A-scans distributed across the macula. This array differs between the Stratus OCT and Cirrus HD-OCT systems. In the Cirrus HD-OCT system, significantly more A-scans are used, and these are evenly distributed over the scanned area. The Stratus OCT employs fewer A-scans, and these are more heavily weighted toward the center of the scan. The Stratus OCT system corrects for this effect by extrapolating across areas not sampled; but, depending on the nature of the macular anatomy in those areas, quantitative differences in macular thickness computations may arise between the OCT systems. Also, although both OCT software systems perform automated delineations of retinal boundaries, each system uses different anatomic landmarks in the specification of the outer retinal boundary (information from the manufacturer, Carl Zeiss Meditec, Inc.). These differences may contribute to a different absolute value for thickness measurements, and may also affect how retinal boundaries are reliably delineated between the two OCT systems.

For both clinical practice and in the conduct of clinical trials, the repeatability of OCT measurements has an important impact on how the data may be interpreted. The multiple differences between the time domain Stratus OCT and the spectral domain Cirrus HD-OCT systems may influence how repeatable macular measurements are in the context of DME where there may be considerable deviation from normal anatomy. Spectral domain OCT has been demonstrated to improve visualization of retinal structures in various macular diseases.10-12 The reliability of macular measurements obtained by using spectral domain OCT, however, has not been determined. Furthermore, a comparison of the reliability of these two OCT technologies in the determination of macular measurements has not been performed. The purpose of this study was to evaluate and compare the reliability of macular measurements obtained using time domain versus spectral domain OCT in patients with DME. The results of this study will provide information on how OCT macular measurements using both time domain and spectral domain technology can be compared and will further our understanding of how different modes of data capture and analysis in OCT systems can influence the measurements.

/pdf/evaluation-of-time-domain-and-spectral-domain-optical-5cd6u0ujc4.pdf

Evaluation of Time Domain and Spectral Domain Optical Coherence Tomography in the Measurement of Diabetic Macular Edema

Purpose
To describe tachyphylaxis to intravitreal bevacizumab (IVB) in patients with exudative age-related macular degeneration (AMD).

/pdf/tachyphylaxis-after-intravitreal-bevacizumab-for-exudative-2gajo6i2pm.pdf

Tachyphylaxis after intravitreal bevacizumab for exudative age-related macular degeneration.

Results From a cohort of 989591 patients, 4384 cases of retinal detachment and 43840 controls were identified. Current use of fluoroquinolones was associated with a higher risk of developing a retinal detachment (3.3% of cases vs 0.6% of controls; adjusted rate ratio [ARR], 4.50 [95% CI, 3.56-5.70]). Neither recent use (0.3% of cases vs 0.2% of controls; ARR, 0.92 [95% CI, 0.45-1.87]) nor past use (6.6% of cases vs 6.1% of controls; ARR, 1.03 [95% CI, 0.89-1.19]) was associated with a retinal detachment. The absolute increase in the risk of a retinal detachment was 4 per 10000 person-years (number needed to harm=2500 computed for any use of fluoroquinolones). There was no evidence of an association between development of a retinal detachment and -lactam antibiotics (ARR, 0.74 [95% CI, 0.35-1.57]) or short-acting -agonists (ARR, 0.95 [95% CI, 0.68-1.33]). Conclusion Patients taking oral fluoroquinolones were at a higher risk of developing a retinal detachment compared with nonusers, although the absolute risk for this condition was small.

https://jamanetwork.com/journals/jama/articlepdf/1148331/joc25028_1414_1419.pdf

Oral Fluoroquinolones and the Risk of Retinal Detachment

Objective—To quantify photoreceptor outer segment (PROS) length in patients with diabetic macular edema (DME) using spectral domain optical coherence tomography (OCT), and to describe the correlation between PROS length and visual acuity in this group of patients. Design—Prospective study. Participants—Twenty-seven consecutive patients (30 eyes) with DME. Methods—Three SD-OCT scans were performed on all eyes during each session using Cirrus™ HD-OCT. A prototype algorithm was developed for quantitative assessment of PROS length. Retinal thicknesses and PROS lengths were calculated for three parameters; macular grid (6mm × 6mm), central subfield (1mm), and center foveal point (0.33mm). Intrasession repeatability was assessed using coefficient of variation (CVW) and intraclass correlation coefficient (ICC). Association between retinal thickness and PROS length with visual acuity was assessed using linear regression and Pearson correlation analyses. Main Outcome Measure—Intrasession repeatability of macular parameters, and correlation of these parameters with visual acuity. Results—Mean retinal thickness and PROS length were 298-381 μm and 30-32 μm, respectively, for macular parameters assessed in this study. CVW values were 0.75-4.13% for retinal thickness, and 1.97-14.01% for PROS length. ICC values were 0.96-0.99 and 0.73-0.98 for retinal thickness and PROS length, respectively. Slopes from linear regression analyses assessing the association of retinal thickness and visual acuity were not significantly different from zero (p>0.20), whereas the slopes of PROS length and visual acuity were significantly different from zero (p<0.0005). Correlation coefficients for macular thickness and visual acuity ranged from 0.13 to 0.22, while coefficients for PROS length and visual acuity ranged from -0.61 to -0.81. Conclusions—PROS length can be quantitatively assessed using Cirrus™ HD-OCT. Although the intrasession repeatability of PROS measurements was less than that of macular thickness measurements, the stronger correlation of PROS length with visual acuity suggests that PROS

/pdf/relationship-between-photoreceptor-outer-segment-length-and-1hw4c2baig.pdf

Farzin Forooghian

Papers

Central Serous Chorioretinopathy: Update on Pathophysiology and Treatment

Evaluation of Time Domain and Spectral Domain Optical Coherence Tomography in the Measurement of Diabetic Macular Edema

Tachyphylaxis after intravitreal bevacizumab for exudative age-related macular degeneration.

Oral Fluoroquinolones and the Risk of Retinal Detachment

Relationship between photoreceptor outer segment length and visual acuity in diabetic macular edema.