The influence of corneal astigmatism on retinal nerve fiber layer thickness and optic nerve head parameter measurements by spectral-domain optical coherence tomography

Exploring optical coherence tomography parameters in eyes with myopic tilted disc

BACKGROUND

To investigate the impact of optic disc torsion (ODT), horizontal disc tilt (HDT) angle, and ovality index (OI) on different retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) segments in healthy myopic eyes.

METHODS

ODT and OI were measured from fundus photographs. HDT angle, peripapillary RNFL, and macular GCIPL were measured by swept-source optical coherence tomography (SS-OCT). The association between optic disc morphology and the RNFL/GCIPL thickness were evaluated, with age and axial length (AL) adjusted.

RESULTS

Among 530 healthy myopic eyes of 284 participants (mean age: 41.7 years, mean spherical equivalent: - 7.70 D, and mean AL: 26.6 mm), 335 eyes (63.2%) had temporal disc torsion (temporal group) and 195 eyes (36.8%) had nasal disc torsion (nasal group). For the nasal group, a larger OI was associated with thinner superior-to-superonasal GCIPL (β = - 7.465 to - 6.972, both P = 0.024) and temporal RNFL sectors (β = - 49.596 to - 27.748, P ≤ 0.014). For the temporal group, a larger OI was associated with thinner superior-to-nasal (β = - 50.255 to - 22.093, P ≤ 0.006) and thicker temporal RNFL sectors (β = 29.015 to 56.890, P ≤ 0.003). Additionally, a larger HDT angle was associated with thinner superior-to-nasal RNFL sectors (β = - 0.559 to - 0.242, P ≤ 0.036) and thinner superior-to-superotemporal GCIPL sectors (β = - 0.084 to - 0.069, P ≤ 0.037).

CONCLUSIONS

The optic disc tortional direction was associated with the measurement of different RNFL and GCIPL sectors independent of the AL and age. These should be considered when constructing a myopic normative database.

Current Status and Future Perspectives of Optic Nerve Imaging in Glaucoma

Being the primary site of degeneration, the optic nerve has always been the focus of structural glaucoma assessment. The technical advancements, mainly of optical coherence tomography (OCT), now allow for a very precise quantification of the optic nerve head and peripapillary retina morphology. By far the most commonly used structural optic nerve parameter is the thickness of the parapapillary retinal nerve fiber, which has great clinical utility but also suffers from significant limitations, mainly in advanced glaucoma. Emerging novel imaging technologies, such as OCT angiography, polarization-sensitive or visible-light OCT and adaptive optics, offer new biomarkers that have the potential to significantly improve structural glaucoma diagnostics. Another great potential lies in the processing of the data already available. Artificial intelligence does not only help increase the reliability of current biomarkers but can also integrate data from various imaging modalities and other clinical measures to increase diagnostic accuracy. And it can, in a more efficient way, draw information from available datasets, such as an OCT scan, compared to the current concept of biomarkers, which only use a fraction of the whole dataset.

Evaluation of Retinal Layer Thicknesses in Patients with Keratoconus Using Retinal Layer Segmentation Analysis

OBJECTIVE

To conduct an evaluation of the effects of irregular astigmatism on the retinal nerve fiber layer (RNFL) and the retinal layers observed using spectral-domain optical coherence tomography (SD-OCT) in patients who had keratoconus (KC).

MATERIALS AND METHODS

A total of 255 eyes from 255 individuals, comprising 72 eyes of KC patients, 70 eyes of patients with astigmia, and 113 eyes of healthy controls were included in the analysis. RNFL scan maps (comprising global, temporal, superotemporal, inferotemporal, nasal, inferonasal, and superonasal maps) and macular thickness (MT) maps of a standard from the Early Treatment Diabetic Retinopathy Study (ETDRS) grid were assessed. The measurements were segmented automatically using Spectralis software, and included the RNFL, inner and outer plexiform layers (IPL, OPL), inner and outer nuclear layers (INL, ONL), ganglion cell layer, retinal pigment epithelium (RPE) in the central 6-mm ETDRS subfield.

RESULTS

The RNFL thickness in the KC group was lower when compared with the other two groups; however, statistically significant differences were noted in the global, temporal, superotemporal, and inferotemporal sectors (p < 0.05 for all). All of the central MT parameters showed significant variation among the groups, while a statistically significant decrease was noted in the KC group, except in the inferior outer sector (p = 0.741). In the segmentation analysis, the KC group had the significantly lowest IPL, ONL, RPE, and outer retinal layer (ORL) thickness among the groups (p < 0.05 for each). The astigmatic group was similar to the control group with regard to these parameters (p > 0.05 for each).

CONCLUSION

The eyes in the KC group appeared to have a thinner RNFL and MT when compared to those in the astigmatic and control groups. The ORLs, especially the ONL and RPE, were the most affected component of the macula in the KC group.

Morphology of the optic nerve head and factors affecting it in the Northern Finland birth cohort

PURPOSE

To assess topographic characteristics of the optic nerve head (ONH) and retinal nerve fibre layer (RNFL) and study the effect of ocular and physiological factors on them in a middle-aged population.

METHODS

A 1552-person randomised sample from Northern Finland population aged 45-49 was examined. Laser scanning tomography and optical coherency tomography were performed to obtain measurements for ONH and RNFL morphology. Measurements of the RNFL included global thickness and the six zones used in automated structure-function analysis (S-F analysis). Influence of central corneal thickness (CCT), refractive correction, intraocular pressure (IOP), anterior chamber angle, gender, blood pressure, height, weight and body mass index (BMI) on tomographic data was analysed.

RESULTS

The optic disc area had a strong correlation with all other parameters of ONH morphology (R = 0.261 to 0.706) as did spherical equivalent (R = -0.280 to 0.280). The correlations between ONH and RNFL measurements were weaker (R = 0.057 to 0.180). Gender, CCT, anterior chamber angle, blood pressure, height and BMI had statistically significant, yet feeble, correlations with a number of ONH parameters.

CONCLUSION

Other than spherical equivalent, the studied anatomical and physiological attributes had little predictive value on the ONH morphology. The optic disc area itself had a significant effect on other measurements of ONH tomography and should be taken into consideration when the thresholds for normal ONH morphology are calculated.

Measuring Retinal Thickness and Visual Acuity in Eyes with Different Types of Astigmatism in a Cohort of Hong Kong Chinese Adults

Purpose

The purpose of this study was to investigate optical coherence tomography (OCT)-measured retinal thickness (RT) and best-corrected distance visual acuity (BCDVA) in eyes with different types of astigmatism.

Methods

This is a case-control study of 101 participants stratified into With-The-Rule (WTR; n = 41), Against-The-Rule (ATR; n = 25), and control (n = 35) groups by noncycloplegic subjective refraction. Inclusion criteria were ages between 18 and 45 years, spherical-equivalent (SE) refraction ≥-10.00 diopters (D), negative cylindrical power (CYL) ≤-0.75 D with axes of 0 to 30 degrees/150 to 180 degrees for WTR and 60 to 120 degrees for ATR, or CYL ≥-0.25 D for controls. Participants suffering from ocular diseases related to retinal defects, having a history of ocular surgery, with BCDVA >0.10 LogMAR, or poor OCT imaging quality were excluded. Fovea-centered scans were performed using spectral-domain OCT (SD-OCT), and RT automatically measured by the inbuilt software. Only right eyes were analyzed. Groups were matched for age, gender, SE, axial length, and corneal curvature.

Results

One-way ANOVA showed a significant difference in both BCDVA (P = 0.039) and macular RT (P = 0.028) among the three groups. Bonferroni's post hoc test revealed statistically significant between-group differences in BCDVA (WTR vs. controls, P = 0.041), as well as in RT at inner-nasal (WTR vs. ATR, P = 0.034) and outer-temporal subfields (WTR vs. controls, P = 0.042). BCDVA was positively associated with macular RT (r = 0.206, P = 0.041) after adjusting for age, gender, and axial length.

Conclusions

Greater RT and poorer BCDVA were found in eyes with WTR astigmatism. Our findings suggest that the effect of astigmatism on retinal thickness and BCDVA may vary depending on not only magnitude, but also axis of astigmatism.

Identification of ocular refraction based on deep learning algorithm as a novel retinoscopy method

BACKGROUND

The evaluation of refraction is indispensable in ophthalmic clinics, generally requiring a refractor or retinoscopy under cycloplegia. Retinal fundus photographs (RFPs) supply a wealth of information related to the human eye and might provide a promising approach that is more convenient and objective. Here, we aimed to develop and validate a fusion model-based deep learning system (FMDLS) to identify ocular refraction via RFPs and compare with the cycloplegic refraction. In this population-based comparative study, we retrospectively collected 11,973 RFPs from May 1, 2020 to November 20, 2021. The performance of the regression models for sphere and cylinder was evaluated using mean absolute error (MAE). The accuracy, sensitivity, specificity, area under the receiver operating characteristic curve, and F1-score were used to evaluate the classification model of the cylinder axis.

RESULTS

Overall, 7873 RFPs were retained for analysis. For sphere and cylinder, the MAE values between the FMDLS and cycloplegic refraction were 0.50 D and 0.31 D, representing an increase of 29.41% and 26.67%, respectively, when compared with the single models. The correlation coefficients (r) were 0.949 and 0.807, respectively. For axis analysis, the accuracy, specificity, sensitivity, and area under the curve value of the classification model were 0.89, 0.941, 0.882, and 0.814, respectively, and the F1-score was 0.88.

CONCLUSIONS

The FMDLS successfully identified the ocular refraction in sphere, cylinder, and axis, and showed good agreement with the cycloplegic refraction. The RFPs can provide not only comprehensive fundus information but also the refractive state of the eye, highlighting their potential clinical value.

Factors Associated with Changes in Peripapillary Retinal Nerve Fibre Layer Thickness in Healthy Myopic Eyes

Myopic people face an elevated risk of primary open angle glaucoma. Changes in the fundus in people with high myopia often lead to misdiagnosis of glaucoma, as this condition has many clinical signs in common with myopia, making the diagnosis of glaucoma more challenging. Compared to reduction of the visual field, a decrease in retinal nerve fibre layer (RNFL) thickness occurs earlier in glaucoma, which is widely considered useful for distinguishing between these conditions. With the development of optical coherence tomography (OCT), RNFL thickness can be measured with good reproducibility. According to previous studies, this variable is not only affected by axial length but also related to the patient's age, gender, ethnicity, optic disc area, and retinal blood flow in myopia. Herein, we intend to summarize the factors relevant to the RNFL in myopia to reduce the false-positive rate of glaucoma diagnosis and facilitate early prevention of myopia.

Effects of Induced Astigmatism on Spectral Domain-OCT Angiography Quantitative Metrics

PURPOSE

To analyze the effect of induced astigmatism on en-face spectral-domain optical coherence tomography angiography quantitative metrics.

DESIGN

Prospective crossover study.

METHODS

Normal eyes without astigmatism and with 0.75, 1.75, and 2.75 diopters (D) of with-the-rule (WTR) astigmatism were imaged using a 3 × 3-mm scan pattern SD-OCTA CIRRUS 5000 HD-OCT with AngioPlex (Carl Zeiss Meditec, Dublin, CA, USA). Quantitative parameters, including foveal avascular zone metrics, parafoveal vessel length density (VD), and perfusion density (PD) were corrected for magnification secondary to axial length and analyzed. Univariate linear regressions were performed within each eye to correlate quantitative metrics to the level of an induced astigmatic cylinder.

RESULTS

Fifteen eyes from 15 patients were imaged. Every 1-D increase in induced WTR astigmatism was associated with a statistically significant decrease in VD and PD within all Early Treatment Diabetic Retinopathy Study inner ring quadrants; however, especially more so nasally (VD: 0.63; P < .001; PD: 0.0089; P = .001). For every 1-D increase in induced astigmatism, the resulting decrease in the inner ring superior quadrant was 12% greater for VD and 16% greater for PD versus that in the inferior quadrant. The resulting decrease in the inner ring nasal quadrant was 40% greater for VD and 48% greater for PD versus that in the temporal quadrant.

CONCLUSIONS

Increasing levels of induced WTR astigmatism correlated with globally diminishing VD and PD, was more symmetrical for vertical than horizontal quadrants, and was most pronounced nasally. This may be due to a high prevalence of horizontally oriented vessels nasally and the horizontal optical defocus induced by WTR astigmatism.

The effect of contact lens wear on retinal spectral domain optical coherence tomography

BACKGROUND

This study assessed the impact of contact lens wear on retinal spectral domain optical coherence tomography (SD-OCT) image quality and macular thickness measurements, among subjects with myopia.

METHODS

This was a prospective study including 34 subjects (26.59 ± 3.19 years) with myopia or myopic astigmatism. Twelve were imaged wearing spherical soft contact lenses, eight non-contact lens wearers were imaged with a plano soft contact lens, and 14 with significant astigmatism were fitted with a rigid gas permeable (RGP) contact lens. For each group of contact lens types, the average image quality index (Q-index), and the average macular thickness measurements were compared between macular OCT scans obtained from the same eyes with and without a contact lens.

RESULTS

Among the subjects assessed with their habitual spherical soft lenses, the average Q-index was similar for scans acquired with and without a contact lens (30.10 ± 1.94 versus 31.03 ± 2.55; p = 0.18). Among non-contact lens wearers, the average Q-index was slightly higher for scans acquired without a contact lens, compared to scans with a plano contact lens (31.99 ± 2.06 versus 29.51 ± 1.56; p = 0.006). Among 14 subjects imaged wearing a fitted RGP contact lens, the Q-index was similar for scans acquired with and without a contact lens (29.04 ± 2.73 versus 28.75 ± 2.86; p = 0.78). In all groups, there were no correlations between the power of the sphere and change in the Q-index (that is, post- minus pre-contact lens Q-index), and no differences were found between OCT-derived macular thickness measurements from scans with and without a contact lens. The magnitude of cylinder was not correlated with the change in the Q-index in the habitual and RGP contact lens groups. However, an inverse correlation between cylinder power and change in the Q-index was found in the plano contact lens group.

CONCLUSION

In low to intermediate levels of myopia, with or without regular astigmatism, macular SD-OCT imaging does not merit placement of a soft or rigid contact lens, nor is there an added benefit from removing a habitual spherical soft lens prior to scanning.

Ophthalmologic Manifestations and Retinal Findings in Children with Down Syndrome

Purpose

To evaluate ocular findings in children with Down syndrome and to compare with the healthy children group.

Methods

The study patients were divided into two groups as the diagnosed Down syndrome group and the control group. The study was designed as a prospective and single-center study in Istanbul University Faculty of Medicine Department of Ophthalmology. The study included 93 patients in the age range from 7 to 18 years, who applied to the ophthalmology department of our clinic in the period from July 2017 to June 2018. The study included the patients allocated into the control group and the Down syndrome patients allocated into the patient group, containing 49 and 44 participants, respectively. All patients underwent complete ophthalmologic examination with biomicroscopy. Autorefractometer measurements were performed in all patients, and the best corrected visual acuity (BCVA) was determined with the use of the Snellen chart. All patients underwent spectral domain optical coherence tomography (SD-OCT) measurements for central foveal retinal (CRT), subfoveal choroidal (CCT), and peripapillary retinal nerve fiber layer (pRNFL) thicknesses.

Results

The average CRT was 241.2 ± 25.7 microns in Down syndrome group and 219.4 ± 21.1 microns in the control group. There was a statistically significant difference between the groups in regards to CRT (p < 0.001). The average pRNFL values were 123.1 ± 15.4 microns in the Down syndrome group and 102.2 ± 8.7 microns in the control group (p < 0.001). The average pRNFL values were 123.1 ± 15.4 microns in the Down syndrome group and 102.2 ± 8.7 microns in the control group (.

Conclusions

In the subjects with Down syndrome, the incidence of lens opacities, strabismus, and amblyopia was higher than the control group. CRT and pRNFL were thicker in the Down syndrome group than in control group. This may represent retinal developmental changes in the patients with Down syndrome.

Optic disc and peripapillary changes by optic coherence tomography in high myopia

Myopia, a worldwide condition, is a multifactorial disease resulting in many ocular complications. Early onset of myopia has a great tendency to develop high myopia and pathological myopia later in life. The pathophysiology and progression of myopia is still unclear. Owing to its involving in visual function, optic disc and peripapillary change in high myopia can't be neglected, and it may help in better understanding of the pathophysiology or mechanism of myopia progression. Recently, advanced imaging techniques have been developed, such as optical coherence tomography (OCT), allowing for better detecting of optic disc and peripapillary change. OCT is a high-resolution and noninvasive measurement for detection of ocular structure. Herein, we provide an updated review of optic disc and peripapillary change in OCT image, including its characteristics and clinical significance. We also propose some problems needed further investigation.

Determinants of peripapillary retinal nerve fiber layer thickness regarding ocular and systemic parameters - the MIPH Eye&Health Study

BACKGROUND

Optical coherence tomography (OCT) allows quantitative image analysis of retinal tissue in vivo. Peripapillary retinal nerve fiber layer (pRNFL) thickness is widely used for evaluation of retinal nerve fiber rarefaction in several optic neuropathies. This study evaluates associations of pRNFL thickness in healthy adult subjects in order to evaluate influencing factors.

METHODS

A cross-sectional study was performed in a working-age population. Only eyes without detectable ocular pathologies were included in the analysis. Among analyzed systemic cardiovascular parameters were age, gender, body-mass index, mean arterial blood pressure, HbA1c, high- and low-density-lipoproteins, and triglycerides. A comprehensive ophthalmological examination including refraction, tonometry, keratometry, and central corneal thickness measurmentwas performed. In addition, pRNFL thickness was imaged by spectral-domain OCT. Univariable and multivariable associations of pRNFL thickness in all four quadrants and on average with systemic and ocular parameters were calculated using a generalized estimating equation model.

RESULTS

Three hundred and six subjects were included. pRNFL thickness measurements showed a significant association with spherical equivalent: pRNFL thickness decreased with increasing myopia in all quadrants (multivariable regression coefficients Beta: superior: 1.16, 95 % CI [0.62;1.71], p < 0.001; temporal: 0.87, [0.33;1.41], p = 0.001; inferior: 1.80, [1.18;2.42], p < 0.001; nasal: 2.60, [2.01;3.20], p < 0.001) and on average (1.51, [1.20;1.82], p < 0.001). A thicker central cornea thickness was related to lower pRNFL in the superior (-0.05, [-0.10; -0.01], p = 0.01), the inferior quadrant (-0.05, [-0.10;0.00], p = 0.03) and on average (-0.04, [-0.07; -0.01], p = 0.02). All other parameters were not  associated.

CONCLUSION

Our findings highlight the importance of refraction when evaluating pRNFL thickness and its independence from other systemic parameters.

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 

Study of Spectral-Domain Optical Coherence Tomography in Children: Normal Values and Influence of Age, Sex, and Refractive Status

Purpose

To establish normal values for retinal nerve fiber layer (RNFL), macular thickness, and macular volume in children using spectral-domain optical coherence tomography (OCT).

Methods

A descriptive cross-sectional study was performed in healthy children between 3 and 14 years of age. Each child underwent a comprehensive ophthalmic examination that included 3 OCT scans with Spectralis (Heidelberg Engineering, Heidelberg, Germany). All measurements were performed by the same operator, and one eye was randomly selected. The influence of age, sex, and refraction on OCT measurements was analyzed.

Results

The sample consisted of 162 Caucasian subjects, mean age 8.1 ± 3.03 years. The spherical equivalent was 0.03 ± 0.19 D (range ±4 D, astigmatism <1 D). The average values were 263.69 ± 4.54 µm for central macular thickness, 0.21 ± 0.01 mm3 for central macular volume, and 100.45 ± 1.98 µm for RNFL. A significant correlation between RNFL and spherical equivalent was found for the nasal (p = 0.001), inferior (p = 0.009), and inferior nasal (p = 0.005) sectors. No differences were found with regard to sex (p>0.05). However, central macular thickness and central macular volume were correlated with age (p = 0.027, p = 0.02).

Conclusions

This study provides reference values for macular thickness, macular volume, and RNFL in healthy children.

Wogonin modulates hydroperoxide-induced apoptosis via PI3K/Akt pathway in retinal pigment epithelium cells

Background

Oxidative stress causes the defects of retinal pigment epithelial (RPE) cells that contribute to age-related macular degeneration (AMD). This study was conducted to determine whether wogonin could prevent H₂O₂-induced oxidative stress in RPE cells.

Methods

A RPE cell line, ARPE-19, was obtained for the cell model. ARPE-19 cells were pre-treated with various concentrations of wogonin for 24 h before being exposed to H₂O₂ for 2 h to induce oxidative stress. Cell metabolic activity was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cellular apoptosis was quantified by the flow cytometry. Protein level was assed by western blot.

Results

The RPE cells exposed to to 200 mM H₂O₂ demonstrated a significant depression in the cell viability; whereas pre-treatment with 50 and 100 mmol/l wogonin could significantly improve the cell viability in a dose-dependent manner. The proportion of PI-positive cells was increased significantly in RPE cells treated with H₂O₂ alone; whereas pretreatment with 100 mM wogonin significantly reduced H₂O₂ -induced RPE cell death rate. In protein level, the wogonin use could reduce the level of p-Akt significantly and this is the possible mechanism of the antioxidant effect of wogonin.

Conclusions

Our study showed that wogonin pre-treatment can protect RPE cells from H₂O₂-induced apoptosis. This suggests potential effect of wogonin in the prevention of retinal diseases associated with H₂O₂-induced oxidative stress such as AMD.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_154

Retinal nerve fiber layer configuration in eyes with epiretinal membrane

PURPOSE

To characterize configurations of the optic nerve head (ONH) and peripapillary retinal nerve fiber layer (RNFL) eyes with epiretinal membrane (ERM).

METHODS

We reviewed medical records of consecutive patients with ERM who were examined between September 2012 and August 2013. Patients were categorized based on the severity of ERM on fundus imaging; patients with ERM but without retinal distortion were in group 1, and patients with ERM and retinal distortion were in group 2. Optic nerve head and RNFL parameters measured by spectral domain optical coherence tomography were assessed and compared between eyes with ERM and normal fellow eyes.

RESULTS

There were no significant differences in ONH and RNFL parameters between ERM eyes and normal fellow eyes in group 1 (n = 12). In group 2 (n = 33), cup volume was smaller (p = 0.020), temporal quadrant RNFL thickness was greater by 18.8 ± 16.6 μm (p < 0.001), and RNFL peak angle was smaller by 18.7 ± 25.3 degrees in ERM eyes compared with fellow eyes (p = 0.001). In the 15 patients in group 2 who underwent ERM removal, temporal quadrant RNFL thickness decreased and the RNFL peak angle increased after the surgery (p = 0.008 and p = 0.001, respectively).

CONCLUSIONS

The configurations of the ONH and peripapillary RNFL in eyes with ERM were different from those in fellow eyes. The characteristic configurations of RNFL such as small peak angle and temporal quadrant thickening may be considered when evaluating parameters as measured by spectral domain optical coherence tomography.

Spectral- and time-domain optical coherence tomography measurements of macular thickness in young myopic eyes

PURPOSE

To evaluate the variation in macular retinal thickness and volume in young Chinese myopic patients using time-domain optical coherence tomography (Stratus TD-OCT) and spectral-domain optical coherence tomography (Cirrus HD-OCT).

METHODS

Ninety-two eyes of 92 myopic subjects were recruited in this study. Based upon spherical equivalence (SE), subjects were divided into two groups: the low to moderate myopia group (-0.5 D ≤ SE < -6.0 D), and the high myopia group (SE ≥ -6.0 D). Stratus TD-OCT and Cirrus HD-OCT were used to compare macular retinal thickness and volume between the two groups. Bland-Altman analysis and Pearson correlation were used to measure agreement between the two OCT systems.

RESULTS

Average macular retinal thickness and total macular volume measured by Cirrus HD-OCT and Stratus TD-OCT of the low to moderate myopia group were 283.52 ± 12.14 μm and 245.38 ± 8.55 μm, respectively, and 10.08 ± 0.37 mm3 and 6.85 ± 0.26 mm3, respectively, and the high myopia groups were 269.58 ± 10.72 μm and 235.65 ± 7.54 μm, respectively, and 9.71 ± 0.36 mm3 and 6.52 ± 0.25 mm3, respectively. The measurements of the two OCTs showed that macular retinal thickness of the parafovea was significantly lower in the high myopia group compared with the low to moderate myopia group, except at the fovea (all P-values less than 0.001, except at the fovea). Using the Bland-Altman method and Pearson correlation, measurements of macular thickness in nine macular retinal subfields and total macular volumes showed good agreement between the two OCTs in myopic eyes (all P-values less than 0.001), with better agreement in the low to moderate myopia group than in the high myopia group.

CONCLUSIONS

The average macular retinal thickness of the fovea did not vary with myopia, while the total volume and retinal thickness of the parafovea were thinner with increasing myopia. There was good agreement between the two OCTs in myopic eyes in all macular subfields, and the Cirrus HD-OCT system provided thicker macular retinal thickness measurements than the Stratus TD-OCT system.

VIRTUAL SLIDES

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1683223414107652.