Comparison of Individual Retinal Layer Thicknesses between Highly Myopic Eyes and Normal Control Eyes Using Retinal Layer Segmentation Analysis

Macular Neural and Microvascular Alterations in Type 2 Diabetes Without Retinopathy: A SS-OCT Study

PURPOSE

To identify specific markers indicative of macular neural and microvascular alterations in individuals with Type 2 Diabetes Mellitus (T2DM) without clinically observable retinopathy.

DESIGN

Prospective cross-sectional study.

METHODS

Using the PLEX Elite 9000, all eyes underwent swept-source optical coherence tomography (SS-OCT) angiography. Quantitative analysis of acquired images compared macular neural and microvascular alterations in T2DM patients without retinopathy to age-matched controls. Precise assessments encompassed measuring the thickness of each individual retinal layer and evaluating macular vascular indices within different capillary plexuses.

RESULTS

Forty-nine T2DM patients and 51 age-matched controls participated. T2DM patients exhibited a significant reduction in the mean macular thickness of the ganglion cell-inner plexiform layer (GC-IPL) (82.5 ± 5.5 µm vs 86.2 ± 5.0 µm, P = .001) and macular retinal nerve fiber layer (RNFL) (45.8 ± 3.0 µm vs 48.1 ± 3.7 µm, P = .001). Furthermore, macular full retinal thickness was significantly lower in diabetic eyes than controls (324.9 ± 16.3 µm vs 332.8 ± 13.7 µm, P = .009). Vascular measurements revealed subtle changes in macular vascular skeleton density within the total capillary plexuses in T2DM patients (0.132 ± 0.005 vs 0.135 ± 0.005, P = .019).

CONCLUSIONS

Metrics derived from SS-OCT, particularly macular RNFL and GC-IPL thicknesses, emerged as superior indicators for the early detection of diabetic retinal disease in individuals with T2DM without clinically observable retinopathy. Further investigations are warranted to comprehensively understand the clinical implications of these findings.

Assessment of changes in macular structural retinal layers in patients with pathological myopia

Background/aim

This study aimed to examine changes in the thickness of individual macular retinal layers in eyes with pathological myopia (PM) and to compare the thickness of each retinal layer between the PM and control groups to gain insights into retinal perfusion.

Materials and methods

The study included 51 eyes in the PM group and 51 eyes in the control group. Optical coherence tomography (OCT) was used to measure the thickness of each retinal layer in the central fovea, parafoveal, and perifoveal regions. Optical coherence tomography angiography (OCT-A) was used to evaluate the retinal capillary density.

Results

In the PM group, the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), and inner nuclear layer (INL) were thicker than in the control group (p = 0.004, p = 0.027, p = 0.020, and p < 0.001, respectively), whereas the outer nuclear layer (ONL) and photoreceptor layer (PRL) were thinner (p = 0.001 and p = 0.003, respectively). In other regions, the RNFL was thicker in the myopic group, whereas the GCL, IPL, INL, and ONL were thinner. OCT-A did not reveal any significant difference between the groups in terms of radial capillary plexus density (p = 0.381); however, the densities of the other plexuses were lower in the PM group.

Conclusions

The results showed alterations in the thickness of retinal layers and capillary plexus density in PM. Thus, assessment of the thickness of individual retinal layers may serve as an indicator of vascular diseases that affect the circulation of the retina and choroid.

Evaluation of Structural Retinal Layer Alterations in Retinitis Pigmentosa

Objective: This study aimed to analyze retinal layers in the macular region using spectral-domain optical coherence tomography (SD-OCT). Additionally, we examined the retinal vascular plexus densities of the eyes using optical coherence tomography angiography (OCT-A), specifically in patients with retinitis pigmentosa (RP). Methods: In the study, 36 eyes from patients with retinitis pigmentosa (RP) and 36 eyes from healthy controls were included. Measurements involved assessing the thicknesses of each retinal layer at the central fovea, parafoveal, and perifovea using spectral domain optical coherence tomography (SD-OCT). Moreover, the study involved the evaluation of retinal capillary plexus densities (RCPD), encompassing deep capillary plexus density values, superficial capillary plexus, and radial peripapillary capillary plexus. This assessment was performed using optical coherence tomography angiography (OCT-A). Results: No statistically significant difference in retinal thickness was found in the central fovea between the two groups. The thicknesses of the INL, OPL, and PRL in the parafoveal regions as well as the RPE in the perifoveal regions increased in the RP group. Nonetheless, the ONL, IPL, GCL, and RNFL demonstrated reduced thickness in both the perifoveal and parafoveal areas. The OCT-A findings indicated that patients with RP exhibited lower values for all RCPD. Conclusion: The retinal layers and RCPD were significantly impacted at varying rates of RP. It is essential to acknowledge that this alteration may be significant in the context of the retinal findings in patients with RP. Abbreviations: SD-OCT = Spectral-domain optical coherence tomography, OCT-A = Optical coherence tomography angiography, RP = Retinitis pigmentosa, ETDRS = Early Treatment Diabetic Retinopathy Study, SD = standard deviation, TRT = Total Retinal Thickness, IRT = Inner Retinal Thickness, ORT = Outer Retinal Thickness, RNFL = Retinal Nerve Fiber Layer, GCL = Ganglion Cell Layer, IPL = Inner Plexiform Layer, INL = inner nuclear layer, OPL = Outer Plexiform Layer, ONL = Outer Nuclear Layer, PRL = Photoreceptor layer, RPE = Retinal Pigment Epithelium, µm = micrometer, PaFoSu = parafovea superior, PeFoSu = perifovea superior, PaFoNa = parafovea nasal, PeFoNa = perifovea nasal, PaFoTe = parafovea temporal, PeFoTe = perifovea temporal, PaFoIn = parafovea inferior, PeFoIn = perifovea inferior.

Effect of shape deprivation on retinal thickness in myopic mice using an OCT method

Purpose

The purpose of this study was to study in retina thickness changes in myopic mice using optical coherence tomography (OCT).

Methods

There were 18 mice in the form-deprivation myopia (FDM) group，in which the left eye was not treated as a control;18 untreated mice served as a normal control group. The diopter of all mice was measured 21 days after birth (P21), before form deprivation. After 4 weeks of form deprivation (P49), the refraction, fundus, and retinal sublayer thickness of all mice were measured.

Results

After 4 weeks of form deprivation, the refractive power of the right eye in the FDM group was significantly higher than that in the left eye (p < 0.05). There was no significant change in the refractive power of the left eye in the FDM group compared with the normal control group. The retina, nerve fiber layer (NFL), inner nuclear layer (INL), and outer nuclear layer (ONL) in the right eye of the FDM group were significantly thinner than those of both the FDM and control groups (p < 0.05). There was no significant change in photoreceptor (PR).

Conclusion

Our study highlights that the myopic mice have decreased R thickness, which might reflect the potential pathological mechanism of myopia.

Identifying the Retinal Layers Linked to Human Contrast Sensitivity Via Deep Learning

Purpose

Luminance contrast is the fundamental building block of human spatial vision. Therefore contrast sensitivity, the reciprocal of contrast threshold required for target detection, has been a barometer of human visual function. Although retinal ganglion cells (RGCs) are known to be involved in contrast coding, it still remains unknown whether the retinal layers containing RGCs are linked to a person's contrast sensitivity (e.g., Pelli-Robson contrast sensitivity) and, if so, to what extent the retinal layers are related to behavioral contrast sensitivity. Thus the current study aims to identify the retinal layers and features critical for predicting a person's contrast sensitivity via deep learning.

Methods

Data were collected from 225 subjects including individuals with either glaucoma, age-related macular degeneration, or normal vision. A deep convolutional neural network trained to predict a person's Pelli-Robson contrast sensitivity from structural retinal images measured with optical coherence tomography was used. Then, activation maps that represent the critical features learned by the network for the output prediction were computed.

Results

The thickness of both ganglion cell and inner plexiform layers, reflecting RGC counts, were found to be significantly correlated with contrast sensitivity (r = 0.26 ∼ 0.58,Ps < 0.001 for different eccentricities). Importantly, the results showed that retinal layers containing RGCs were the critical features the network uses to predict a person's contrast sensitivity (an average R² = 0.36 ± 0.10).

Conclusions

The findings confirmed the structure and function relationship for contrast sensitivity while highlighting the role of RGC density for human contrast sensitivity.

Agreement of different OCT scan directions for individual retinal-layer thickness measurements in multiple sclerosis subjects with prior unilateral optic neuritis

The similarities between horizontal and vertical Optical Coherence Tomography (OCT) scans for the individual retinal layer thickness measurements in the macula was evaluated. Two volumetric scans (B-scans oriented horizontally and vertically) were performed in 64 multiple sclerosis subjects with history of unilateral optic neuritis and 64 healthy controls. The agreement between the thickness measurements with horizontal and vertical OCT scans was evaluated in 3 groups of eyes: healthy controls, eyes with history of optic neuritis and the fellow eyes. The mean difference in individual layer thickness between the scans was smaller than the instrument’s axial resolution in all 3 groups. The limit of agreement (LoA) varied among the different layers and sectors analyzed and this trend was similar in all the groups. For the inner retinal layers (retinal nerve fiber layer to inner nuclear layer), the inner macular sectors had a larger LoA compared to the corresponding outer sectors. In the outer plexiform and nuclear layers, the central and inner sectors (except inner temporal) had LoA larger than the other sectors and layers. The larger LoA seen for different layers and sectors suggests that the scan direction must be same for the follow-up OCT measurements and in clinical studies.

Associations of refractive errors and retinal changes measured by optical coherence tomography: A systematic review and meta-analysis

Studies reporting alteration in retinal thickness using optical coherence tomography (OCT) have been performed in different populations with various degrees of refractive error, producing inconsistent results. Therefore, we performed a meta-analysis to evaluate the alterations in retinal OCT measurements in myopic and hyperopic patients compared to controls. Evaluation of different retinal layers' thickness may have significance for developing novel approaches for preventing, diagnosing, and treating refractive errors and their complications. We searched PubMed and EMBASE to identify articles that reported OCT measurements of different retinal layers and regions, including macular, foveal, parafoveal, perifoveal, foveolar, ganglion cell complex (GCC), retinal nerve fiber layer (RNFL), peripapillary retinal nerve fiber layer (pRNFL), and ganglion cell and inner plexiform layer (GC-IPL) thickness in addition to macular volume, and optic disc area in myopes and hyperopes comparing their differences with controls. We applied either a fixed-effects or random-effects model for the meta-analysis of these differences based on the assessed heterogeneity level. Furthermore, subgroup analyses and metaregression, as well as publication bias and quality assessment, were conducted for the eligible studies. Forty-seven studies with a total of 12223 eyes, including 8600 cases and 3623 non-cases, are included in this meta-analysis. Our results showed that, in comparison to controls, highly myopic eyes had a significantly lower value for mean macular thickness, macular GCC, macular GC-IPL, parafoveal, perifoveal, foveal, foveolar, RNFL, and pRNFL thickness. Compared to controls, moderately myopic eyes showed a significantly thinner mean macular GCC layer and pRNFL. On the other hand, hyperopic eyes had significantly thicker average pRNFL than controls. Several other significant differences were also observed in various regional analyses. The findings of the current study affirm the retinal OCT measurement differences between myopic and hyperopic eyes compared to controls, emphasizing OCT measurements' advantages as potential biomarkers of ocular pathologies.

Relationship of Sighting Ocular Dominance with Macular Photostress Test Time and Thickness of the Middle Macular Layers

SIGNIFICANCE

The mechanisms of sighting ocular dominance, which is particularly important in monovision therapies and sports vision, are not fully understood yet. Whether the macula affects ocular dominance or ocular dominance affects the macula is also a subject of interest.

PURPOSE

The aim of this study was to investigate the relationship of sighting ocular dominance with macular photostress test time and middle macular layer thickness.

METHODS

One-hundred eyes of 50 healthy adult volunteers were included in this cross-sectional study. Sighting eye dominance was decided by a hole-in-the-card test. The macular photostress test was performed by exposing the eye to the ophthalmoscope light for 10 seconds and measuring the time taken to return to visual acuity within one row of pre-light exposure acuity. The spectral-domain optical coherence tomography examinations were performed to measure thickness of middle macular layers (i.e., outer nuclear, outer plexiform, inner nuclear, and inner plexiform). Refractive error and intraocular pressure (IOP) measurements were also recorded.

RESULTS

The comparison of dominant and nondominant eyes in the aspect of refractive error, IOP, and macular photostress test time did not show statistically significant differences (P > .05). The thicknesses of macular outer nuclear, outer plexiform, inner nuclear, and inner plexiform layers were similar in the dominant and nondominant eyes (P > .05). In addition, macular photostress time was not statistically significantly correlated with the thickness of middle macular layers (P > .05).

CONCLUSIONS

The thickness of middle macular layers and macular photostress recovery time are similar in dominant and nondominant eyes.