Relationship of Gender, Body Mass Index, and Axial Length with Central Retinal Thickness Using Optical Coherence Tomography

Alteration of retinal layers in healthy subjects over 60 years of age until nonagenarians

Purpose

To assess alterations of retinal layers in healthy subjects over 60 years old.

Methods

Retinal layers of 160 healthy subjects (aged 60–100 years) without any retinal pathology were imaged using spectral domain optical coherence tomography. Mean thickness of retinal nerve fiber layer, ganglion cell/inner plexiform layer (GCLIPL), inner nuclear layer, outer plexiform layer/outer nuclear layer, photoreceptor complex (PR) and retinal thickness (RT) were measured in a 3.45 mm grid. Correlations between age and layers were estimated and linear regression equations were calculated. Different age-groups (60–69, 70–79, 80–89 years and nonagenarians, each group with 40 participants) were compared.

Results

Significant age-thickness correlations were observed for GCLIPL (P<0.001, r=−0.394), PR (P<0.001, r=−0.370) and RT (P<0.001, r=−0.290). A comparison between age groups 60–69 years and nonagenarians showed no significant thickness alteration of retinal nerve fiber layer (21.80±2.18 μm vs 22.82±2.97 μm, P=0.163), inner nuclear layer (37.23±3.02 μm vs 36.01±3.24 μm, P=0.07) and outer plexiform layer/outer nuclear layer (104.95±6.56 μm vs 104.23±7.59 μm, P=0.567), while GCLIPL (83.35±7.35 μm vs 74.38±9.09 μm), PR (83.03±3.31 μm vs 79.34±2.09 μm) and RT (330.64±12.63 μm vs 316.83±18.35 μm) showed a significant decrease (P<0.001 for all).

Conclusion

Our study provides normative data of alterations of retinal layers for persons aged 60 years to nonagenarians and indicates a continuous decrease of RT, PR, and GCLIPL. This data may be useful for clinical trials investigating macular diseases in older patients.

Effects of hemodialysis on macular and retinal nerve fiber layer thicknesses in non-diabetic patients with end stage renal failure

OBJECTIVES

To evaluate the thicknesses of retinal nerve fiber layer (RNFL) and macula by fourier-domain (FD) optical coherence tomography (OCT) in non-diabetic patients with end-stage-renal-failure (ESRF) undergoing hemodialysis (HD).

METHODS

This is a prospective and observational study. Both eyes of 20 patients receiving HD (group 1) and 34 control patients (group 2) were evaluated by FD-OCT. Macular and RNFL thicknesses were compared between groups and their correlation with age, duration of HD, and gender were examined. In group 1, macular and RNFL thicknesses were evaluated before and shortly after HD in the first day, first and sixth months.  

RESULTS

In group 1, pre-HD temporal, inferior, average RNFL thicknesses were thinner than group 2. This thinning did not correlate with duration of HD, age and gender. Pre-HD macular thicknesses were thinner than group 2. These thinnings did not correlate with age, but the thinnings at superior, nasal and average thickness correlated negatively with duration of HD. Nasal, temporal, and average macular thicknesses were thinner in female patients. The thickenings of RNFL and macula that were observed in the after HD first day and first month did not showed consistency in the sixth month except superior quadrant RNFL.

CONCLUSION

Macular and RNFL thicknesses of patients receiving HD were less than the normal population. Age has no effect on these thinnings. The duration of HD affects more than gender. Hemodialysis  session  causes a consistent increase in superior quadrant RNFL.

Lateral thinking - Interocular symmetry and asymmetry in neurovascular patterning, in health and disease

No biological system or structure is likely to be perfectly symmetrical, or have identical right and left forms. This review explores the evidence for eye and visual pathway asymmetry, in health and in disease, and attempts to provide guidance for those studying the structure and function of the visual system, where recognition of symmetry or asymmetry may be essential. The principal question with regards to asymmetry is not 'are the eyes the same?', for some degree of asymmetry is pervasive, but 'when are they importantly different?'. Knowing if right and left eyes are 'importantly different' could have significant consequences for deciding whether right or left eyes are included in an analysis or for examining the association between a phenotype and ocular parameter. The presence of significant asymmetry would also have important implications for the design of normative databases of retinal and optic nerve metrics. In this review, we highlight not only the universal presence of asymmetry, but provide evidence that some elements of the visual system are inherently more asymmetric than others, pointing to the need for improved normative data to explain sources of asymmetry and their impact on determining associations with genetic, environmental or health-related factors and ultimately in clinical practice.

The Distribution of Macular Thickness and Its Determinants in a Healthy Population

PURPOSE

To determine the distribution of macular thickness in a healthy Iranian population aged 45-69 years and its association with certain determinants.

METHODS

All participants underwent optometric examinations including measurement of uncorrected and corrected visual acuity, objective refraction by retinoscopy, and subjective refraction. Subsequently, all participants underwent slit-lamp biomicroscopy followed by fundus examination through direct and indirect ophthalmoscopy, and optical coherence tomography (OCT) imaging under pupil dilation.

RESULTS

Mean central macular thickness was 255.4 µm (95% confidence interval, CI, 254.5-256.3 µm), average inner macular thickness was 316.5 µm (95% CI 315.9-317.1 µm), average outer macular thickness was 275.3 µm (95% CI 274.8-275.8 µm), and overall average thickness was 278.6 µm (95% CI 278.1-279.1 µm). A linear multiple regression model showed that all indexes were significantly larger in male participants (p < 0.001). Central macular thickness increased with age (coef = 0.25, p < 0.001) while overall, inner and outer macular thickness decreased with age (coef = -0.18, -0.15, -0.19, respectively, all p < 0.001). Central and inner macular thickness had a positive correlation (coef = 3.8, 2.6, respectively, both p < 0.001) and outer macular thickness had a negative correlation (coef = -1.6, p < 0.001) with axial length.

CONCLUSION

Age, sex, refractive error, axial length, and keratometry were found to be associated with macular thickness. These factors should be taken into account when interpreting macular thickness measurements with spectral-domain OCT.

Macular thicknesses and their associations with ocular and demographic variables in black South Africans

Purpose: To determine normal macular thicknesses and their associations with demographic and ocular variables in healthy eyes of black South Africans.Methods: Six hundred healthy subjects (N = 600) underwent height and weight measurements followed by a complete ophthalmic examination, which included auto-refraction, subjective refraction, slit-lamp biomicroscopy, ocular biometric measurements and tonometry. Intraocular pressure (IOP) was measured with the Nidek NT530P (Tonopachy™) and the axial length (AL) thickness with the Nidek Echoscan. The central corneal thickness (CCT) and macular thickness were measured using iVue-100 spectral-domain optical coherence tomography (Optovue, Inc.). The macular thickness map protocol that divides the macular area into nine regions of the Early Treatment Diabetic Retinopathy Study (ETDRS) fields was used. Variations in macular thickness measurements with body mass index (BMI), age, gender, refraction, AL, CCT and IOP were determined with partial correlation analysis.Results: The 600 subjects had a mean age of 28.15 ± 13.09 years (range = 10–66 years), with 305 (50.83%) being males and 295 (49.17%) females. The thickness values of the central, inner and outer maculae were normally distributed, with means of 235.89 µm ± 20.04 µm, 303.56 µm ± 18.68 µm and 287.81 µm ± 14.61 µm, respectively. Mean total macular thickness for all subjects was 268.72 ± 15.04 µm. The temporal quadrant was markedly thinner than all other quadrants for both inner and outer macular regions. Macular thicknesses were greater in men than in women (p < 0.05). The thickness of mean central, mean inner and mean outer maculae increased significantly with increasing BMI (p < 0.001). Central, inner and outer maculae were significantly associated (p < 0.001) with a high hyperopic spherical equivalent refraction. AL was associated with a thin inner macula (p < 0.05) and an outer macula (p < 0.001), but not with a thinner central macula (p > 0.05). Age, CCT and IOP were not associated with macular thickness values in any quadrant (p > 0.05).Conclusion: The macular values were thinner in women than in men and were related to BMI, gender, hyperopic spherical refraction and AL with regional variations. These differences should be considered when interpreting optical coherence tomography results for accurately diagnosing and managing retinal abnormalities.

Macular thickness in healthy Saudi adults. A spectral-domain optical coherence tomography study

Objectives:

To determine the macular thickness in the eyes of healthy Saudi adults using spectral-domain optical coherence tomography (SD-OCT).

Methods:

This is a prospective, cross-sectional study, including 158 healthy participants between August and December 2015. Mean subject age was 29.9 ± 7.85 years old. All participants underwent full ophthalmic evaluation, including SD-OCT imaging, and axial length measurement. Data from the right eye were included. Mean retinal thickness was determined. Correlations between retinal thickness and gender, age, axial length, and spherical equivalence were analyzed.

Results:

Mean central retinal thickness was 244.76 ± 23.62 µm, mean axial length was 23.8 ± 1.062 mm (range: 20.5-29 mm) and mean spherical equivalent was -0.31 ± 1.75 diopters (D) (range: -5.50 to +4.25 D). Central subfield (CSF) thickness and foveal volume were significantly lower in women than in men (both p<0.001). Data from the various age groups did not show statistically significant differences in the CSF thickness (p=0.389) or foveal volume (p=0.341). A positive correlation between CSF thickness and axial length (p<0.001) was observed.

Conclusion:

The normal macular thickness values in healthy Saudi individuals is different from that reported in other ethnic groups, as obtained by SD-OCT. Saudi men had thicker CSF than Saudi women and axial length was positively correlated to the central foveal thickness.

Foveal slope measurements in diabetic retinopathy: Can it predict development of sight-threatening retinopathy? Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study (SN-DREAMS II, Report no 8)

Aim:

The aim was to assess the foveal slope configuration in subjects with type 2 diabetes in a population-based study.

Materials and Methods:

A subset of 668 subjects from Sankara Nethralaya Diabetic Retinopathy (DR) Epidemiology and Molecular Genetics Study II, a population-based study, were included in the current study. All the subjects underwent comprehensive ophthalmic evaluation including spectral domain optical coherence tomography. Foveal thickness was assessed in five central early treatment DR study quadrants from the three-dimensional scan and foveal slope was calculated in all the four quadrants.

Results:

Subjects with sight-threatening DR (STDR) had significantly shallow foveal slope in inferior quadrant (STDR: 7.33 ± 6.26 vs. controls: 10.31 ± 3.44; P = 0.021) when compared to controls and in superior (STDR: 7.62 ± 5.81 vs. no DR: 9.11 ± 2.82; P = 0.033), inferior (STDR: 7.33 ± 6.26 vs. no DR: 8.81 ± 2.81; P = 0.048), and temporal quadrants (STDR: 6.69 ± 5.70 vs. no DR: 7.97 ± 2.33; P = 0.030) when compared to subjects with no DR. Foveal slope was significantly shallow among the older age groups in subjects with no DR (P < 0.001) and non-STDR (P = 0.027). Average foveal slope in the diabetic subjects was independently and significantly correlated with increase in age (r = −0.241; P < 0.001) and central subfield thickness (r = −0.542; P < 0.001).

Conclusion:

Changes in foveal slope were seen with increasing age; however, in diabetes these segmental slope changes can be seen in late DR (STDR).

Retinal nerve fiber layer thickness in a healthy Turkish population measured by optical coherence tomography

BACKGROUND

Normative optical coherence tomography (OCT) data is required for different subsets of the population as ethnic differences in retinal nerve fiber layer (RNFL) thickness have been reported. An OCT database for the normal Turkish population is not commercially available.

OBJECTIVES

Quantify peripapillary RNFL thickness in a Turkish population.

DESIGN

Cross-sectional, descriptive study.

SETTING

Numune Training and Research Hospital, Adana, Turkey.

SUBJECTS AND METHODS

RNFL measurements performed by Spectral OCT with a circular scan with 3.4 mm circle were centered around the optic disc of the right eye of each subject. Correlation of the effects of age and gender on RNFL thickness was analyzed.

MAIN OUTCOME MEASURE(S)

Correlation and measurements of RNFL. Retinal nerve fiber layer thick- ness measurements were obtained for the entire circumference of the optic nerve head.

RESULTS

In 307 healthy subjects consisting of 135 (44%) males and 172 (56%) females, with a mean (SD) age of 35.1 (9.6) years (range, 20-50 years), RNFL was superior: 132.2 (16.63) micro m, inferior: 139.1 (14.53) micro m, nasal: 96.2 (14.23) micro m, temporal: 79.8 (10.7) micro m. The mean (SD) RNFL thickness for the group was 111.5 (9.3) micro m. There was no significant difference between the average RNFL thicknesses of age groups nor between males and females (P=.1, P=.42), and no significant correlation with respect to age (P=.430, r=-.04). There was a statistically significant difference between the inferior quadrants of the two genders (P=.04).

CONCLUSIONS

RNFL thickness did not vary significantly with gender. A weak negative but statistically nonsignificant correlation between average RNFL thickness and age was found.

LIMITATIONS

The participants were young adults or at early middle age so age effects on RNFL thickness may not be explained. The data does not reflect the entire Turkish population, which is not homogeneous.

Macular thickness and volume in the elderly: A systematic review

Ageing leads to a number of changes in the body including the macula. Detailed imaging using optical coherence tomography have enabled in vivo studies of how macula changes with age. Here we systematically review 49 studies (9115 participants and 11,577 eyes) to provide an overview of how ageing manifests in the macula of the elderly focusing on clinical relevant measures that are thicknesses and volumes of different macular areas. Ageing seems to increase center point foveal thickness. Ageing does not seem to change the center subfield thickness significantly. Ageing decreases the inner and outer macular thickness, and the overall macular thickness and volume. Studies find that specific retinal layers at specific locations seem to be the contributor to these changes. These findings confirm that age-related changes suggested in histological studies are measurable in vivo on thickness and volume and differ depending on location. Studies are needed to explore reasons for the large variance in measurements and how ageing by itself contributes to development of macular disease.

Choroidal and Retinal Thickness in Children With Different Refractive Status Measured by Swept-Source Optical Coherence Tomography

PURPOSE

To investigate the choroidal and retinal thickness in myopic, emmetropic, and hyperopic Chinese children by swept-source longer-wavelength optical coherence tomography.

DESIGN

Cross-sectional study.

METHODS

Two-hundred and seventy-six schoolchildren aged 7-13 years underwent comprehensive ophthalmic examinations, including cycloplegic refraction, and swept-source optical coherence tomography measurements. The thickness of the choroid, retina, ganglion cell layer, and nerve fiber layer were compared among children of different refractive status. The topographic variation and factors related to the thickness of the choroid and retinal layers were analyzed.

RESULTS

Compared to emmetropic subjects, those with myopia had a significantly thinner choroid in all regions (P < .01), and hyperopic subjects had a thicker choroid in most regions (P < .05). The myopic retinas were thinner than those of emmetropic or hyperopic subjects in the superior parafoveal and all 4 perifoveal subfields (P < .05), but no other subfields differed significantly among different refractive groups (P > .05). The axial length and refractive diopters were independently related to central foveal choroidal thickness (R(2) = 0.17, P < .01), while age and intraocular pressure were independently associated with central fovea retinal (R(2) = 0.15, P < .01) and ganglion cell layer thicknesses (R(2) = 0.10, P < .01) after adjustment for other systematic and ocular factors. Central foveal choroidal and retinal thickness were unrelated in children of different refractive status (P > .05).

CONCLUSIONS

Choroidal thickness, but not retinal thickness, correlated closely with axial length and refractive diopters in Chinese children. Choroid thinning occurs before retina thinning early in myopic progression.

CORRELATION OF FOVEAL AVASCULAR ZONE SIZE WITH FOVEAL MORPHOLOGY IN NORMAL EYES USING OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

PURPOSE

To analyze the foveal avascular zone (FAZ) in normal eyes using optical coherence tomography angiography.

METHODS

Prospective noncomparative case series. The parafoveal region of 70 eyes from 67 healthy subjects was imaged using optical coherence tomography angiography to visualize the superficial and deep capillary plexuses and correlated with standard macular volume scans using spectral domain optical coherence tomography to determine foveal morphology.

RESULTS

In all 70 eyes imaged, 2 vascular plexuses could be detected within the retina: a superficial plexus within the ganglion cell layer and a deep plexus within the inner nuclear layer. A measurable FAZ was visualized in both plexuses in all imaged eyes. The FAZ area was variable in the study population with a mean of 0.266 mm² ± 0.097 mm² in the superficial plexus (range: 0.071 mm²-0.527 mm²) and a mean of 0.495 mm² ± 0.227 mm² in the deep plexus (range: 0.160 mm²-0.795 mm²). The FAZ area was significantly larger in the deep plexus (P < 0.0001) compared with superficial plexus. The FAZ area in both plexuses correlated inversely with central macular thickness and central macular volume (P < 0.0001). No significant correlation was found between superficial plexus FAZ area and age (P = 0.55) or sex (P = 0.34). In the same manner, no significant correlation was found between deep plexus FAZ area and age (P = 0.13) or sex (P = 0.13).

CONCLUSION

Optical coherence tomography angiography provides a noninvasive method to visualize and measure the superficial and deep plexus FAZ in a normal population. The FAZ can vary in size and shape, with the FAZ area significantly larger in the deep compared with the superficial plexus. Both superficial and deep FAZ area correlate inversely with foveal thickness and volume.

Normal Macular Thickness in Healthy Indian Eyes Using Spectral Domain Optical Coherence Tomography

PURPOSE

To determine macular thickness and its variation with age and sex in healthy Indian eyes using Zeiss spectral domain optical coherence tomography (SD-OCT).

DESIGN

A prospective, cross-sectional study.

METHODS

Four hundred healthy adult subjects (≥18 years) underwent macular cube scanning using Zeiss SD-OCT. Macular thickness from all 9 regions of the Early Treatment Diabetic Retinopathy Study map was documented for each subject. Variations in macular thickness by age and sex were determined.

RESULTS

The mean age of the subjects was 38.05 ± 12.13 (range, 18-78) years. The mean ages in men and women were 39.19 ± 12.16 and 37.13 ± 12.05 years, respectively (P > 0.05). The mean central subfield thickness (CST) of all subjects was 240.40 ± 18.26 μm, and mean macular thickness was 287.87 ± 18.07 μm. The mean CST in the right and left eyes were 240.40 ± 18.25 μm and 239.65 ± 17.73 μm, respectively (P = 0.55). Males were associated with greater mean CST and mean macular thickness compared with females (P < 0.05). There was an association of mean CST with sex (adjusted r = 0.095; P < 0.05) but not with age. Overall, the nasal quadrant was the thickest followed by the superior, inferior, and temporal subfields.

CONCLUSIONS

This is the normative data for macular thickness in healthy Indian eyes using Zeiss SD-OCT. This will serve as a baseline for diagnosing and treating macular pathologies in Indian eyes because such data using Zeiss SD-OCT in Indian eyes have previously been lacking.

Quantitative spectral domain optical coherence tomography thickness parameters in type II diabetes

Purpose:

To elucidate the changes in retinal thickness and individual layer thickness in subjects with diabetic retinopathy (DR) using spectral domain optical coherence tomography (SDOCT).

Materials and Methods:

A total of 251 eyes from 170 subjects were included in this study. The study sample was subdivided into nondiabetic subjects; subjects with diabetes but no DR; subjects with mild, moderate, and severe nonproliferative DR (NPDR); and proliferative DR. Various retinal thickness parameters were assessed using SDOCT.

Results:

The mean age of the study population was 55.34 ± 9.02 years (range: 32–80 years) and 56.6% of the subjects were males. Men had significantly greater central foveal thickness, central subfield thickness, retinal nerve fiber layer thickness, and retinal thickness in all the quadrants of 3 mm and 6 mm zones compared to women (P < 0.001). Superior (293.11 ± 25.46 vs. 285.25 ± 19.17; P = 0.044) and temporal (282.10 ± 25.26 vs. 272.46 ± 16.21; P = 0.011) quadrants showed an increased retinal thickness in any DR group when compared with diabetic subjects without DR. Photoreceptor layer thickness was significantly reduced in diabetic subjects with no DR when compared with nondiabetic subjects and also in cases of severe NPDR when compared with mild and moderate NPDR.

Conclusion:

Here, we analyze the quantitative retinal thickness parameters in diabetic subjects using SDOCT. Neuronal degenerative changes such as photoreceptor and retinal pigment epithelial thinning in case of DR are also reported.

A review of the human retina with emphasis on nerve fibre layer and macula thicknesses

The retina is the innermost neural layer of the eye, and is the site of transformation of light energy into a neural signal. Knowledge and assessment of the human retinal structural parameters are important for the appropriate diagnosis and management of various ocular diseases. For instance, potentially blinding eye diseases, such as glaucoma and age-related macula degeneration, cause structural changes in the retina. Clinical evidence with ocular coherence tomography also suggests that eyes with glaucoma lose retinal nerve fibre layer and ganglion cells axons before loss of visual function. These losses appear as a visible change in the optic nerve head and can be seen before visual field abnormalities are noticed by the patient. This review discusses certain aspects (anatomical structures, structural changes with eye diseases and assessment methods) involving the human retina, their clinical importance and factors that may influence them. The content of this article will be useful to optometrists and ophthalmologists who assess these parameters in normal patients as well as in those with eye conditions such as glaucoma.Keywords: Retinal parameters; optic disc; nerve fibre layer thickness; macula thickness; glaucoma 

Macular thickness and macular volume measurements using spectral domain optical coherence tomography in normal Nepalese eyes

PURPOSE

To record the normative values for macular thickness and macular volume in normal Nepalese eyes.

METHODS

In all, 126 eyes of 63 emmetropic subjects (mean age: 21.17±6.76 years; range: 10-37 years) were assessed for macular thickness and macular volume, using spectral domain-optical coherence tomography over 6×6 mm(2) in the posterior pole. A fast macular thickness protocol was employed. Statistics such as the mean, median, standard deviation, percentiles, and range were used, while a P-value was set at 0.05 to test significance.

RESULTS

Average macular thickness and total macular volume were larger in males compared to females. With each year of increasing age, these variables decreased by 0.556 μm and 0.0156 mm(3) for average macular thickness and total macular volume, respectively. The macular thickness was greatest in the inner superior section and lowest at the center of the fovea. The volume was greatest in the outer nasal section and thinnest in the fovea. The central subfield thickness (r=-0.243, P=0.055) and foveal volume (r=0.216, P=0.09) did not correlate with age.

CONCLUSION

Males and females differ significantly with regard to macular thickness and macular volume measurements. Reports by other studies that the increase in axial length reduced thickness and volume, were negated by this study which found a positive correlation among axial length, thickness, and volume.

Retinal Tissue Thickness is Reduced in Diabetic Peripheral Neuropathy

AIM

To investigate the relationship between diabetic peripheral neuropathy (DPN) and retinal tissue thickness.

METHODS

Full retinal thickness in the central retinal, parafoveal, and perifoveal zones and thickness of the ganglion cell complex and retinal nerve fiber layer (RNFL) were assessed in 193 individuals (84 with type 1 diabetes, 67 with type 2 diabetes, and 42 healthy controls) using spectral domain optical coherence tomography. Among those with diabetes, 44 had neuropathy defined using a modified neuropathy disability score recorded on a 0-10 scale. Multiple regression analysis was performed to investigate the relationship between diabetic neuropathy and retinal tissue thickness, adjusted for the presence of diabetic retinopathy (DR), age, sex, duration of diabetes, and HbA_1c levels.

RESULTS

In individuals with diabetes, perifoveal thickness was inversely related to the severity of neuropathy (p < 0.05), when adjusted for age, sex, duration of diabetes, and HbA_1c levels. DR was associated with reduced thickness in parafovea (p < 0.01). The RNFL was thinner in individuals with greater degrees of neuropathy (p < 0.04).

CONCLUSIONS

DPN is associated with structural compromise involving several retinal layers. This compromise may represent a threat to visual integrity and therefore warrants examination of functional correlates.

Macular Thickness in Myopia: An OCT Study of Young Chinese Patients

PURPOSES

To investigate macular thickness (MT) in young myopic Chinese patients using Spectralis optical coherence tomography (OCT) and to assess its association with gender, axial length (AL), spherical equivalent (SE), and intraocular pressure (IOP).

METHODS

Included in this study were 133 myopic Chinese patients, aged 18-30 years. All underwent complete ophthalmic examinations and Spectralis OCT. Inner, central, and outer foveal regions of the macula were measured.

RESULTS

The central fovea was the thinnest of the three macular regions (mean thickness, 250.1 ± 15.3 μm). Women had consistently thinner MTs than did men, except in the outer superior and inferior areas. Central foveal thickness (CFT) was positively correlated with AL and negatively correlated with SE. In the inner and outer regions, MT was positively correlated with SE. AL was negatively correlated with MT in all quadrants of the inner and outer sectors, but not the inner superior and outer nasal areas. No macular measurement was significantly correlated with age or IOP in either gender.

CONCLUSIONS

Variables affecting MT should be considered when evaluating SD-OCT data in young myopic Chinese patients, with and without retinal diseases.

Normative Spectral Domain Optical Coherence Tomography Data in Healthy Turkish Children

PURPOSE

To determine the normative database of macular and retinal nerve fiber layer (RNFL) thickness parameters in healthy Turkish children by OCT.

METHODS

318 eyes of 318 children (138 boys, 183 girls) aged between 3 and 17 years were evaluated. The children were scanned by Cirrus HD-OCT (Carl Zeiss Meditec) to measure the macula, RNFL, and optic nerve head parameters.

RESULTS

Axial length (AL) (p < 0.001, R²= 0.08), spherical equivalent (SE) (p < 0.001, R²= 0.12), and rim area (p < 0.001, R²= 0.15) were the strongest predictors of RNFL thickness. All of the macular measurements were significantly related to age (p < 0.001, R²> 5%). Average macular thickness (p < 0.01) and outer macula (p = 0.002) showed significant relationship with the AL and SE.

CONCLUSION

This study ensures an age-adjusted pediatric normative database using OCT to diagnose and monitor macular diseases, optic nerve diseases, and glaucoma in children.

The Effect of Axial Length on the Thickness of Intraretinal Layers of the Macula

Purpose

The aim of this study was to evaluate the effect of axial length (AL) on the thickness of intraretinal layers in the macula using optical coherence tomography (OCT) image analysis.

Methods

Fifty three randomly selected eyes of 53 healthy subjects were recruited for this study. The median age of the participants was 29 years (range: 6 to 67 years). AL was measured for each eye using a Lenstar LS 900 device. OCT imaging of the macula was also performed by Stratus OCT. OCTRIMA software was used to process the raw OCT scans and to determine the weighted mean thickness of 6 intraretinal layers and the total retina. Partial correlation test was performed to assess the correlation between the AL and the thickness values.

Results

Total retinal thickness showed moderate negative correlation with AL (r = -0.378, p = 0.0007), while no correlation was observed between the thickness of the retinal nerve fiber layer (RNFL), ganglion cell layer (GCC), retinal pigment epithelium (RPE) and AL. Moderate negative correlation was observed also between the thickness of the ganglion cell layer and inner plexiform layer complex (GCL+IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL) and AL which were more pronounced in the peripheral ring (r = -0.402, p = 0.004; r = -0.429, p = 0.002; r = -0.360, p = 0.01; r = -0.448, p = 0.001).

Conclusions

Our results have shown that the thickness of the nuclear layers and the total retina is correlated with AL. The reason underlying this could be the lateral stretching capability of these layers; however, further research is warranted to prove this theory. Our results suggest that the effect of AL on retinal layers should be taken into account in future studies.

Cirrhosis-induced morphological changes in the retina: possible role of endogenous opioid

AIM

To investigate the impact of cirrhosis on retinal morphology and to evaluate the role of endogenous opioids as a mediator in cirrhosis induced retinal change.

METHODS

Thirty-six male rats were divided into 3 main groups; the common bile duct ligated (BDL) group, the sham-operated (Sham) group and the unoperated (Unop) group. Then each of these three main groups was divided into two subgroups; the first subgroup received daily injection of naltrexone hydrochloride (NTX) and the second group was injected with normal saline (Saline) daily. After 28d, rats were anesthetized and their right eyes were enucleated and assessed for histological changes. The thickness of the rod and cons layer, outer nuclear layer, outer plexiform layer, inner nuclear layer, inner plexiform layer and ganglion cell layer for each eye were measured in micrometers by light microscope.

RESULTS

Ganglion cell layer showed significant increase in thickness in the BDL group (P<0.05). This increase was eliminated in the group where BDL rats received daily intraperitoneal injection of naltrexone hydrochloride (20 mg/kg). No other histological changes were detected in the other 5 layers we measured.

CONCLUSION

The morphological change we detected in the retina of cirrhotic rats is probably due to opioids increased tone in cirrhosis since the increase in thickness in the ganglion cell layer was almost eliminated when naltrexone hydrochloride was injected. These results suggest a possible role for endogenous opioids in the morphological retinal changes detected in cirrhotic rats.

Central Macular Thickness in Children with Myopia, Emmetropia, and Hyperopia: An Optical Coherence Tomography Study

Purpose. To investigate the central macular thickness (CMT) in myopic, emmetropic, and hyperopic Chinese children using Optical Coherence Tomography. Methods. 168 right eyes of Chinese subjects aged 4–18 were divided into 3 groups based on their postcycloplegic spherical equivalent: myopes (<−1.0 D); emmetropes (≥−1.0 to ≤+1.0 D); and hyperopes (>+1.0 D) and the CMT was compared before/after age adjustment. The CMT was correlated with age, axial length, and peripapillary retinal nerve fibre layer (RNFL). Results. The mean CMT was 274.9 ± 50.3 μm and the mean population age was 7.6 ± 3.3 years. The CMT was thickest in the myopes (283.3 ± 57.3 μm, n = 56), followed by the hyperopes (266.2 ± 55.31 μm, n = 60) and then emmetropes (259.8 ± 28.7 μm, n = 52) (all P < 0.0001). When adjusted for age, myopes had a thicker CMT than the other 2 groups (all P < 0.0001) but there was no CMT difference between the emmetropes and hyperopes (P > 0.05). There was no significant correlation between CMT with age, axial length, or peripapillary RNFL (all P ≥ 0.2). Conclusion. Chinese children with myopia had a thicker CMT than those with emmetropia or hyperopia. There was no correlation of the CMT with age, axial length, or peripapillary RNFL thickness.

Clinical Insights Into Foveal Morphology in Albinism

PURPOSE

A hallmark of albinism is foveal hypoplasia. However, literature suggests variable foveal development. This study evaluates the association between ocular phenotype and foveal morphology to demonstrate the broad structural and functional spectrum.

METHODS

Best-corrected visual acuity (BCVA), nystagmus, angle kappa, stereoacuity, iris transillumination, macular melanin presence, foveal avascular zone, and annular reflex were recorded in 14 patients with albinism. Spectral-domain optical coherence tomography provided macular images.

RESULTS

The clinical phenotype was broad, with BCVA varying from 20/20 to 20/100. Better BCVA was associated with a preserved foveal avascular zone, annular macular reflex, stereoacuity, and macular melanin. Imaging demonstrated a continuum of foveal development correlating with BCVA. Individuals with a rudimentary pit had normal inner and outer segment lengthening and better BCVA.

CONCLUSIONS

The spectrum of ocular structure and visual function in albinism is broad, suggesting a possible diagnosis of albinism in a patient with an even more normal clinical presentation.

Normative spectral domain optical coherence tomography data on macular and retinal nerve fiber layer thickness in Indians

Aim:

To provide the normative data of macular and retinal nerve fiber layer (RNFL) thickness in Indians using spectral domain OCT (Spectralis OCT, Heidelberg Engineering, Germany) and to evaluate the effects of age, gender, and refraction on these parameters.

Design:

Observational, cross-sectional study.

Materials and Methods:

The eyes of 105 healthy patients aged between 20-75 years, with no ocular disease and best corrected visual acuity of 20/20, were scanned using standard scanning protocols by a single examiner. Exclusion criteria included glaucoma, retinal diseases, diabetes, history of prior intraocular surgery or laser treatment. The mean macular and RNFL thickness were recorded, and the effects of age, gender, and refraction on these parameters were evaluated. This data was compared with published literature on Caucasians to assess the ethnic variations of these parameters.

Results:

The normal central foveal thickness in healthy Indian eyes measured using Spectralis OCT was 260.1 ± 18.19 μm. The nasal inner quadrant showed maximum retinal thickness (338.88 ± 18.17 μm). The mean RNFL thickness was 101.43 ± 8.63 μm with maximum thickness in the inferior quadrant. The central foveal thickness showed a gender-based difference (P = 0.005) but did not correlate significantly with age (P = 0.134), whereas the parafoveal, perifoveal thickness, macular volume, and RNFL thickness showed significant negative correlation with age.

Conclusions:

Our study provides the normative database for Indians on Spectralis OCT. It also suggests that age should be considered while interpreting the macular thickness and RNFL, whereas gender should also be given consideration in central foveal thickness.

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 > 0.05) or axial length (r = 0.09, p > 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.

The association between macular thickness and peripapillary retinal nerve fiber layer thickness in Chinese children

To investigate the association between macular thickness and peripapillary retinal nerve fiber layer (RNFL) thickness in Chinese children. This cross-sectional study recruited consecutive cases of healthy pediatric subjects aged 4 to 18 from Caritas Medical Centre in Hong Kong Special Administrative Region, China, from 2013 to 2014. Subjects with only eye, ocular tumors, congenital glaucoma, congenital cataract, congenital nystagmus, microphthalmos, optic nerve or retinal disease, active ocular infections, corneal scars, and severe visual impairment of any cause were excluded. Peripapillary RNFL thickness and macular thickness at 1-mm-diameter fovea center (C1), 3-mm-diameter temporal quadrant (T3), and 3-mm-diameter nasal quadrant (N3) were measured with optical coherence tomography. Best-corrected visual acuity, axial length, and cycloplegic refraction were also recorded. Spearman correlation was used to analyze the association between T3, C1, and N3 with each of the following: average and quadrant RNFL thickness, axial length, and spherical equivalent. In 179 subjects, the mean age was 7.9 ± 3.6 years. There were 90 male and 89 female subjects, all of Chinese ethnicity. The mean spherical equivalent was -0.1 ± 3.1 D and mean axial length was 22.9 ± 1.4 mm. There were significant and positive correlations of the average (T3: r = 0.20, P = 0.04; N3: r = 0.2, P = 0.005), superior (T3: r = 0.20, P = 0.03; N3: r = 0.2, P = 0.03), and inferior (T3: r = 0.20, P = 0.02; N3: r = 0.2, P = 0.01) peripapillary RNFL thicknesses with the T3 and N3 macular thicknesses but not C1. The nasal peripapillary RNFL thickness was also positively correlated with T3 (r = 0.20, P = 0.01). There were no significant associations between the macular thickness (T3, C1, N3) with neither the spherical equivalent (P > 0.2) nor the axial length (P > 0.3). The macular thickness was positive correlated with the peripapillary RNFL thickness in a population of healthy Chinese children.

Assessment of perfused foveal microvascular density and identification of nonperfused capillaries in healthy and vasculopathic eyes

PURPOSE

To analyze the foveal microvasculature of young healthy eyes and older vasculopathic eyes, imaged using in vivo adaptive optics scanning light ophthalmoscope fluorescein angiography (AOSLO FA).

METHODS

AOSLO FA imaging of the superficial retinal microvasculature within an 800-μm radius from the foveal center was performed using simultaneous confocal infrared (IR) reflectance (790 nm) and fluorescence (488 nm) channels. Corresponding IR structural and FA perfusion maps were compared with each other to identify nonperfused capillaries adjacent to the foveal avascular zone. Microvascular densities were calculated from skeletonized FA perfusion maps.

RESULTS

Sixteen healthy adults (26 eyes; mean age 25 years, range, 21-29) and six patients with a retinal vasculopathy (six eyes; mean age 55 years, range, 44-70) were imaged. At least one nonperfused capillary was observed in five of the 16 healthy nonfellow eyes and in four of the six vasculopathic eyes. Compared with healthy eyes, capillary nonperfusion in the vasculopathic eyes was more extensive. Microvascular density of the 16 healthy nonfellow eyes was 42.0 ± 4.2 mm(-1) (range, 33-50 mm(-1)). All six vasculopathic eyes had decreased microvascular densities.

CONCLUSIONS

AOSLO FA provides an in vivo method for estimating foveal microvascular density and reveals occult nonperfused retinal capillaries. Nonperfused capillaries in healthy young adults may represent a normal variation and/or an early sign of pathology. Although limited, the normative data presented here is a step toward developing clinically useful microvascular parameters for ocular and/or systemic diseases.

Macular thickness measurements using Copernicus Spectral Domain Optical Coherence Tomography

PURPOSE

To provide normal macular thickness measurements using Spectral Domain Optical Coherence Tomography (SDOCT, Copernicus, Optopol Technologies, Zawierci, Poland).

METHODS

Fifty-eight eyes of 58 healthy subjects were included in this prospective study. All subjects had comprehensive ophthalmic examination including best-corrected visual acuity (BCVA). All the subjects underwent Copernicus SDOCT. Central foveal thickness (CFT) and photoreceptor layer (PRL) thickness were measured and expressed as mean and standard deviation. Mean retinal thickness for each of the 9 regions defined in the Early Treatment Diabetic Retinopathy Study was reported. The data were compared with published literature in Indians using Stratus and Spectralis OCTs to assess variation in instrument measurements.

RESULTS

The mean CFT in the study sample was 173.8 ± 18.16 microns (131-215 microns) and the mean PRL thickness was 65.48 ± 4.23 microns (56-74 microns). No significant difference (p = 0.148) was found between CFT measured automated (179.28 ± 22 microns) and manually (173.83 ± 18.1 microns). CFT was significantly lower in women (167.62 ± 16.36 microns) compared to men (180.03 ± 18 microns) (p = 0.008). Mean retinal thickness reported in this study was significantly different from published literature using Stratus OCT and Spectralis OCT.

CONCLUSION

We report the normal mean retinal thickness in central 1 mm area to be between 138 and 242 microns in Indian population using Copernicus SDOCT. We suggest that different OCT instruments cannot be used interchangeably for the measurement of macular thickness as they vary in segmentation algorithms.

Associations between narrow angle and adult anthropometry: the Liwan Eye Study

PURPOSE

To assess the associations between narrow angle and adult anthropometry.

METHODS

Chinese adults aged 50 years and older were recruited from a population-based survey in the Liwan District of Guangzhou, China. Narrow angle was defined as the posterior trabecular meshwork not visible under static gonioscopy in at least three quadrants (i.e. a circumference of at least 270°). Logistic regression models were used to examine the associations between narrow angle and anthropomorphic measures (height, weight and body mass index, BMI).

RESULTS

Among the 912 participants, lower weight, shorter height, and lower BMI were significantly associated with narrower angle width (tests for trend: mean angle width in degrees vs weight p < 0.001; vs height p < 0.001; vs BMI p = 0.012). In univariate analyses, shorter height, lower weight and lower BMI were all significantly associated with greater odds of narrow angle. The crude association between height and narrow angle was largely attributable to a stronger association with age and sex. Lower BMI and weight remained significantly associated with narrow angle after adjustment for height, age, sex, axial ocular biometric measures and education. In analyses stratified by sex, the association between BMI and narrow angle was only observed in women.

CONCLUSION

Lower BMI and weight were associated with significantly greater odds of narrow angle after adjusting for age, education, axial ocular biometric measures and height. The odds of narrow angle increased 7% per 1 unit decrease in BMI. This association was most evident in women.

Measurement of retinal thickness in macular region of high myopic eyes using spectral domain OCT

AIM

To investigate the changes of retinal thickness in macula of high myopic eyes using spectral domain optical coherence tomography (OCT).

METHODS

Middle-aged and young myopic patients were divided into three groups according to their refractive error/axial length: low and medium myopia group (LMMG), high myopia group (HMG) and super high myopia group (SHMG). Cirrus HD-OCT was used to evaluate total average macular thickness, central subfield thickness, inner/outer macular thickness and macular volume. The differences among experimental groups were analyzed by one-factor analysis of variance. Associations between macular thickness and refractive error/axial length were analyzed by Pearson correlation analysis.

RESULTS

There was no significant difference in age among the three groups (P=0.2789). The mean refraction error in the LMMG, HMG, and SHMG groups was -2.49±1.38D, -8.53±1.95D and -13.88±1.76D, respectively (P<0.001). The central subfield thickness of three groups was 244.56±12.19µm, 254.33±11.61µm and 261.75±11.83µm, respectively, and there were statistically significance between random two groups. The total average macular thickness, inner/outer macular thickness, and macular volume decreased with increased myopia/axial length. Average foveal thickness had negative correlations with refractive error (P<0.001), and positive correlations with axial length. The inferior and temporal inner macular thickness, all the quadrants of outer ring, total average macular thickness and macular volume featured positive correlations with refractive error, and negative correlations with axial length. Average foveal thickness, superior and temporal inner macular thicknesses, and temporal outer macular thickness was lower in females compared to males.

CONCLUSION

With an increase in myopia degree/axial length, the average foveal thickness increased and the inner/outer macular thickness decreased. Females featured thicker average foveal thickness, and thinner macular thickness compared to males.

A morphological study of retinal changes in unilateral amblyopia using optical coherence tomography image segmentation

OBJECTIVE

The purpose of this study was to evaluate the possible structural changes of the macula in patients with unilateral amblyopia using optical coherence tomography (OCT) image segmentation.

PATIENTS AND METHODS

38 consecutive patients (16 male; mean age 32.4±17.6 years; range 6-67 years) with unilateral amblyopia were involved in this study. OCT examinations were performed with a time-domain OCT device, and a custom-built OCT image analysis software (OCTRIMA) was used for OCT image segmentation. The axial length (AL) was measured by a LenStar LS 900 device. Macular layer thickness, AL and manifest spherical equivalent refraction (MRSE) of the amblyopic eye were compared to that of the fellow eye. We studied if the type of amblyopia (strabismus without anisometropia, anisometropia without strabismus, strabismus with anisometropia) had any influence on macular layer thickness values.

RESULTS

There was significant difference between the amblyopic and fellow eyes in MRSE and AL in all subgroups. Comparing the amblyopic and fellow eyes, we found a statistically significant difference only in the thickness of the outer nuclear layer in the central region using linear mixed model analysis keeping AL and age under control (p = 0.032). There was no significant difference in interocular difference in the thickness of any macular layers between the subgroups with one-way between-groups ANCOVA while statistically controlling for interocular difference in AL and age.

CONCLUSIONS

According to our results there are subtle changes in amblyopic eyes affecting the outer nuclear layer of the fovea suggesting the possible involvement of the photoreceptors. However, further studies are warranted to support this hypothesis.

Foveal thickness in healthy fellow eyes of patients with unilateral macular holes

PURPOSE

To compare the morphologic parameters of ophthalmoscopically and tomographically normal foveae of the fellow eyes of patients with a unilateral macular hole (MH), other unilateral retinal diseases, and healthy eyes.

DESIGN

Observational, cross-sectional study.

METHODS

Of the 849 subjects studied, 183 eyes were excluded because they had an abnormal vitreofoveal interface that might have affected the foveal thickness. The average regional retinal thicknesses of the Early Treatment Diabetic Retinopathy Study sectors determined by spectral-domain optical coherence tomography were compared among 160 patients with MH, 175 patients with epiretinal membrane, 145 patients with retinal vein occlusion, and 186 healthy subjects. The foveal depression was quantified as the foveal pit depth divided by the foveal pit diameter.

RESULTS

The fovea (1 mm) and central fovea were significantly thinner in the MH group (243 and 192 μm) than in the other groups (P < .0001). There were no significant differences in the thickness of the fovea and central fovea among the eyes with epiretinal membrane (254 and 203 μm) or retinal vein occlusion (251 and 202 μm) or in the healthy group (254 and 201 μm). The foveal depression was significantly greater in the MH group (0.063) than in the retinal vein occlusion group (0.059) or in the healthy group (0.058; P = .014 and P = .0014, respectively). Multiple regression analyses showed that a thinner fovea and a deeper foveal depression were associated significantly with the presence of MH (P = .0054 to P < .0001).

CONCLUSIONS

These results suggest that patients with MH have unique foveal morphologic features that predispose them to MH development.

Relationship between macular ganglion cell complex thickness and macular outer retinal thickness: a spectral-domain optical coherence tomography study

BACKGROUND

To assess the relationship between macular ganglion cell complex and macular outer retinal thicknesses.

DESIGN

Case-control study.

PARTICIPANTS

Forty-two normal eyes and 91 eyes with primary open-angle glaucoma were studied.

METHODS

Spectral-domain optical coherence tomography (RTVue-100) was used to measure the macular ganglion cell complex and macular outer retinal thickness. Ganglion cell complex to outer retinal thickness ratio was also calculated.

MAIN OUTCOME MEASURES

The relationships between the ganglion cell complex and outer retinal thicknesses and between the ganglion cell complex to outer retinal thickness ratio and outer retinal thickness were evaluated.

RESULTS

There was a positive correlation between ganglion cell complex and outer retinal thicknesses in the normal group and the glaucoma group (r = 0.53, P < 0.001 and r = 0.42, P < 0.001, respectively). In that respect, there was no correlation between ganglion cell complex to outer retinal thickness ratio and outer retinal thickness in the both groups (r = -0.07, P = 0.657, and r = 0.04, P = 0.677, respectively). The ganglion cell complex to outer retinal thickness ratio was 55.65% in the normal group, 45.07% in the glaucoma group. This difference was statistically significant.

CONCLUSIONS

The ganglion cell complex thickness may be affected by outer retinal thickness, and there is individual variation in the outer retinal thickness. Therefore, when determining the ganglion cell complex, it seems necessary to consider the outer retinal thickness as well. We propose the ratio as a suitable parameter to account for individual variations in outer retinal thickness.

Cone structure in patients with usher syndrome type III and mutations in the Clarin 1 gene

OBJECTIVE

To study macular structure and function in patients with Usher syndrome type III (USH3) caused by mutations in the Clarin 1 gene (CLRN1).

METHODS

High-resolution macular images were obtained by adaptive optics scanning laser ophthalmoscopy and spectral domain optical coherence tomography in 3 patients with USH3 and were compared with those of age-similar control subjects. Vision function measures included best-corrected visual acuity, kinetic and static perimetry, and full-field electroretinography. Coding regions of the CLRN1 gene were sequenced.

RESULTS

CLRN1 mutations were present in all the patients; a 20-year-old man showed compound heterozygous mutations (p.N48K and p.S188X), and 2 unrelated women aged 25 and 32 years had homozygous mutations (p.N48K). Best-corrected visual acuity ranged from 20/16 to 20/40, with scotomas beginning at 3° eccentricity. The inner segment-outer segment junction or the inner segment ellipsoid band was disrupted within 1° to 4° of the fovea, and the foveal inner and outer segment layers were significantly thinner than normal. Cones near the fovea in patients 1 and 2 showed normal spacing, and the preserved region ended abruptly. Retinal pigment epithelial cells were visible in patient 3 where cones were lost.

CONCLUSIONS

Cones were observed centrally but not in regions with scotomas, and retinal pigment epithelial cells were visible in regions without cones in patients with CLRN1 mutations. High-resolution measures of retinal structure demonstrate patterns of cone loss associated with CLRN1 mutations.

CLINICAL RELEVANCE

These findings provide insight into the effect of CLRN1 mutations on macular cone structure, which has implications for the development of treatments for USH3.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00254605.

Retinal thickness in people with diabetes and minimal or no diabetic retinopathy: Heidelberg Spectralis optical coherence tomography

PURPOSE

To evaluate macular thickness in people with diabetes but minimal or no retinopathy using Heidelberg Spectralis optical coherence tomography (OCT).

METHODS

In a multicenter, cross-sectional study of mean retinal thickness, on Spectralis OCT in the nine standard OCT subfields, spanning a zone with 6-mm diameter, center point, and total retinal volume were evaluated. Central subfield (CSF) thickness was evaluated for association with demographic and clinical factors. Stratus OCT scans also were performed on each participant.

RESULTS

The analysis included 122 eyes (122 participants) with diabetes and no (n = 103) or minimal diabetic retinopathy (n = 19) and no macular retinal thickening on clinical exam. Average CSF thickness was 270 ± 24 μm. Central subfield thickness was significantly greater in males relative to females (mean 278 ± 23 μm vs. 262 ± 22 μm, P < 0.001). After adjusting for gender, no additional factors were found to be significantly associated with CSF thickness (P > 0.10). Mean Stratus OCT CSF thickness was 199 ± 24 μm.

CONCLUSIONS

Mean CSF thickness is approximately 70 μm thicker when measured with Heidelberg Spectralis OCT as compared with Stratus OCT among individuals with diabetes in the absence of retinopathy or with minimal nonproliferative retinopathy and a normal macular architecture. CSF thickness values ≥ 320 μm for males and 305 μm for females (~2 SDs above the average for this normative cohort) are proposed as gender-specific thickness levels to have reasonable certainty that diabetic macular edema involving the CSF is present using Spectralis measurements.

Sex & vision I: Spatio-temporal resolution

BACKGROUND

Cerebral cortex has a very large number of testosterone receptors, which could be a basis for sex differences in sensory functions. For example, audition has clear sex differences, which are related to serum testosterone levels. Of all major sensory systems only vision has not been examined for sex differences, which is surprising because occipital lobe (primary visual projection area) may have the highest density of testosterone receptors in the cortex. We have examined a basic visual function: spatial and temporal pattern resolution and acuity.

METHODS

We tested large groups of young adults with normal vision. They were screened with a battery of standard tests that examined acuity, color vision, and stereopsis. We sampled the visual system's contrast-sensitivity function (CSF) across the entire spatio-temporal space: 6 spatial frequencies at each of 5 temporal rates. Stimuli were gratings with sinusoidal luminance profiles generated on a special-purpose computer screen; their contrast was also sinusoidally modulated in time. We measured threshold contrasts using a criterion-free (forced-choice), adaptive psychophysical method (QUEST algorithm). Also, each individual's acuity limit was estimated by fitting his or her data with a model and extrapolating to find the spatial frequency corresponding to 100% contrast.

RESULTS

At a very low temporal rate, the spatial CSF was the canonical inverted-U; but for higher temporal rates, the maxima of the spatial CSFs shifted: Observers lost sensitivity at high spatial frequencies and gained sensitivity at low frequencies; also, all the maxima of the CSFs shifted by about the same amount in spatial frequency. Main effect: there was a significant (ANOVA) sex difference. Across the entire spatio-temporal domain, males were more sensitive, especially at higher spatial frequencies; similarly males had significantly better acuity at all temporal rates.

CONCLUSION

As with other sensory systems, there are marked sex differences in vision. The CSFs we measure are largely determined by inputs from specific sets of thalamic neurons to individual neurons in primary visual cortex. This convergence from thalamus to cortex is guided by cortex during embryogenesis. We suggest that testosterone plays a major role, leading to different connectivities in males and in females. But, for whatever reasons, we find that males have significantly greater sensitivity for fine detail and for rapidly moving stimuli. One interpretation is that this is consistent with sex roles in hunter-gatherer societies.

Choroidal volume variations with age, axial length, and sex in healthy subjects: a three-dimensional analysis

PURPOSE

To demonstrate the 3-dimensional choroidal volume distribution in healthy subjects using enhanced depth imaging (EDI) spectral-domain optical coherence tomography (SD-OCT) and to evaluate its association with age, sex, and axial length.

DESIGN

Retrospective case series.

PARTICIPANTS

A total of 176 eyes from 114 subjects with no retinal or choroidal disease.

METHODS

The EDI SD-OCT imaging studies of healthy patients who had undergone a 31-raster scanning protocol on a commercial SD-OCT device were reviewed. Manual segmentation of the choroid was performed by 2 retinal specialists. A macular choroidal volume map and 3-dimensional topography were automatically created by the built-in software of the device. Mean choroidal volume was calculated for each Early Treatment Diabetic Retinopathy Study (ETDRS) subfield. Regression analyses were used to evaluate the correlation between macular choroidal volume and age, sex, and axial length.

MAIN OUTCOME MEASURES

Three-dimensional topography and ETDRS-style volume map of the choroid.

RESULTS

Three-dimensional topography of the choroid and volume map was obtained in all cases. The mean choroidal volume was 0.228 ± 0.077 mm(3) for the center ring and 7.374 ± 2.181 mm(3) for the total ETDRS grid. The nasal quadrant showed the lowest choroidal volume, and the superior quadrant showed the highest choroidal volume. The temporal and inferior quadrants did not show different choroidal volume values. Choroidal volume in all the EDTRS rings was significantly correlated with axial length after adjustment for age (P < 0.0001), age after adjustment for axial length (P < 0.0001), and sex after adjustment for axial length (P < 0.05). Choroidal volume decreases by 0.54 mm(3) (7.32%) for every decade and by 0.56 mm(3) (7.59%) for every millimeter of axial length. Male subjects have a 7.37% greater choroidal volume compared with that of female subjects.

CONCLUSIONS

Enhanced depth imaging SD-OCT is a noninvasive and well-tolerated procedure with an excellent ability to visualize 3-dimensional topography of the choroid and to measure choroidal volume at the posterior pole using manual segmentation. Age and axial length are inversely correlated with choroidal volume, most likely leading to changes in retinal metabolic support in elderly, highly myopic patients. Sexual differences should be considered when interpreting an EDI SD-OCT scan of the choroid.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Spectral-domain optical coherence tomography in subjects over 60 years of age, and its implications for designing clinical trials

Aims

To study the variability of central retinal thickness (CRT), its concordance to the fellow eye, and the implications for designing future clinical trials using spectral-domain optical coherence tomography (SD-OCT).

Methods

Cross-sectional retrospective analysis of European Genetic Database. 632 eyes of 316 subjects over 60 years of age without macular pathology were examined using SD-OCT.

Results

Mean CRT was 280.22 µm and 281.02 µm for the right and left eyes, respectively. There was a strong concordance for all measured values between right and left eyes. Men had significantly thicker CRT than women. Variation up to 23 µm difference between both eyes was seen. To detect a change of at least 30 µm in CRT, a sample size of 90 or 176 per group is needed for a single-arm or double-arm study, respectively (α=0.05, power=0.80, no loss to follow up, assuming SD in future studies=100 µm).

Conclusions

Clinical trials using CRT as an endpoint are feasible in terms of sample size needed.

Comparison of central macular thickness between two spectral-domain optical coherence tomography in elderly non-mydriatic eyes

AIM

To compare central macular thickness (CMT) measurements obtained by two spectral-domain optical coherence tomography (SD-OCT) exams, and to evaluate measurement reproducibility and agreement between these two exams, and to investigate the relationship between CMT and possible influencing factors such as age, sex, eye (OD/OS), and operators in elderly non-mydriatic eyes.

METHODS

Seventy-two normal subjects were included. Every subject underwent CMT measurement twice using one of two SD-OCT (OSE-2000, Moptim, Shenzhen, China & 3-D OCT-1000, Topcon, Tokyo, Japan) instruments respectively where we randomly chose one eye in each patient for the test; these exams were performed by two operators over an hour period with a brief rest between sessions. Comparison of the OSE-2000 and 3-D OCT-1000 CMT measurements was based on paired-t test. The mean difference between the CMT measurements was calculated. General linear model analyzed the relationships among eye (OD/OS), operator, sex, and CMT values using age as co-variant. All tests were considered statistically significant at P<0.05. The main outcome measures included CMT.

RESULTS

When evaluated with general linear model analysis, CMT measurements were found to have high reproducibility across the two instruments between the two operators for the OSE-2000 single line scan and 3-D OCT-1000 macular scans (P=0.731; P=0.443). There was statistically significant difference in CMT values between the two instruments (P<0.001) and the mean difference was -46.83µm at 95% confidence limits (-49.15,-44.51). Age was positively correlated with CMT (beta coefficient = 0.516, P=0.001; beta coefficient = 0.453, P=0.009) and sex was correlated with CMT from the OSE-2000 (P=0.021) but not with the 3-D OCT-1000 (P=0.056). According to the actual thickness measurements, the CMT of the male was thicker than the female's but there was no statistical difference. There was interaction between sex and eye in OSE-2000 and not in 3-D OCT-1000 (P=0.02; P=0.374). No significant correlation was found between CMT and the influencing factor of eye in both of the instruments (P=0.884; P=0.492).

CONCLUSION

Reproducibility of CMT measurement using the two SD-OCTs is excellent in normal eyes according to the operator factor analysis. OSE-2000 has a different posterior retinal boundary of CMT measurement, which results in the CMT value differences, compared with the 3-D OCT-1000. Age is positively correlated with CMT measurement while sex is correlated with CMT in the OSE-2000 but not in the 3-D OCT-1000 and eye (OD/OS) had no correlation with CMT values. Mydriatic drops may not be necessary for CMT measurement using high scan rate SD-OCT in normal eyes in dark room.

Macular thickness by age and gender in healthy eyes using spectral domain optical coherence tomography

Purpose

To determine normal macular thickness and its variation by age and gender in healthy eyes using spectral-domain optical coherence tomography (SD-OCT).

Methods

In this cross-sectional analysis, two hundred and twenty eyes of 220 healthy subjects underwent raster scanning using Topcon SD-OCT system, at the Department of Ophthalmology, Dow University of Health Sciences and Civil Hospital Karachi, Pakistan. Macular thickness from all 9 regions of the ETDRS map was documented for each subject. Variations in macular thickness measurements by age and gender were determined.

Results

The 220 subjects had a mean age of 45.3 years (16–80 years). Using the ETDRS map, foveal thickness for all subjects was measured to be 229±20.46 µm. Mean macular thickness for all subjects was 262.8±13.34 µm. Male gender was associated with greater foveal (p<0.0001) and mean macular (p<0.0001) thickness compared to females. There was no association of mean macular thickness (r² = 0.01; p>0.05) and foveal thickness (r² = 0.00004; p>0.05) with age.

Conclusion

We have provided normative data for macular thickness using Topcon SD-OCT system. Our results are comparable to some and vary from other reports using the similar OCT system. Our results suggest that male gender is associated with greater macular thickness, while macular thickness has no association with age in healthy eyes. This is the first normative data for macular thickness from Pakistan; benchmark for diagnosing and monitoring macular pathologies. The values obtained in this study may be useful for comparison with other populations, other SD-OCT systems and future imaging technologies.

Influence of diabetes on macular thickness measured using optical coherence tomography: the Singapore Indian Eye Study

PURPOSE

To determine the influence of diabetes, diabetic retinopathy (DR), and other factors on macular thickness, measured using optical coherence tomography (OCT), in a population-based sample.

METHODS

Data from the population-based Singapore Indian Eye Study were analyzed. We measured macular thickness using Stratus OCT Fast Macular Thickness scan protocol in 228 participants with diabetes mellitus (including 167 without DR, 44 with mild DR, 17 with moderate or severe DR) and 72 non-diabetic controls without macular oedema or other macular lesions. Analysis was done on right eyes.

RESULTS

The mean age of participants was 60.1 ± 10.1 years, with 53.8% men. Macular thickness measurements did not differ significantly between diabetic participants with no or mild DR and non-diabetic participants. Diabetic participants with moderate or severe DR had greater foveal and temporal outer macula thickness compared with those with no or mild DR (P=0.003). In a multivariate linear regression model, older age (P=0.009), male gender (P=0.005), and lower spherical equivalent (P=0.001) were other factors associated with greater foveal thickness in all participants after controlling for body mass index, glycosylated haemoglobin, total cholesterol, and mean systolic blood pressure.

CONCLUSION

This population-based study showed that diabetic participants with moderate or severe DR had thicker foveal measurements, even in the absence of diabetic macula oedema, than non-diabetic controls. Other factors that influenced macular thickness measurements were age, gender, and spherical equivalent. These data may aid the interpretation of OCT findings in persons with diabetes and DR.

Race- and sex-related differences in retinal thickness and foveal pit morphology

PURPOSE

To examine sex- and race-associated differences in macular thickness and foveal pit morphology by using spectral-domain optical coherence tomography (SD-OCT).

METHODS

One hundred eighty eyes of 90 healthy patients (43 women, 47 men) underwent retinal imaging with spectral-domain OCT. The lateral scale of each macular volume scan was corrected for individual differences in axial length by ocular biometry. From these corrected volumes, Early Treatment Diabetic Retinopathy Study (ETDRS) grids of retinal thickness were generated and compared between the groups. Foveal morphology was measured with previously described algorithms.

RESULTS

Compared with the Caucasians, the Africans and African Americans had reduced central subfield thickness. Central subfield thickness was also reduced in the women compared with the men, although the women also showed significant thinning in parafoveal regions. There was no difference between the sexes in foveal pit morphology; however, the Africans/African Americans had significantly deeper and broader foveal pits than the Caucasians.

CONCLUSIONS

Previous studies have reported race- and sex-associated differences in macular thickness, and the inference has been that these differences represent similar anatomic features. However, the data on pit morphology collected in the present study reveal an important and significant variation. Between the sexes, the differences are due to global variability in retinal thickness, whereas the variation in thickness observed between the races appears to be driven by differences in foveal pit morphology. These differences have important implications for the use of SD-OCT in detecting and diagnosing retinal disease.