Inner Plexiform Layer Thickness Research Articles

The effects of electronic cigarette smoking on retinal nerve fiber layer, ganglion cell layer, inner plexiform layer, and choroidal thickness

Purpose To compare the thickness of the retinal nerve fibre layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), and choroid in healthy electronic cigarette smokers and non-smokers using spectral domain optical coherence tomography (SD-OCT). Material and Method 25 healthy electronic cigarette smokers and 25 age- and gender-matched healthy non-smokers were included in the study. RNFL, GCL, IPL and choroidal thickness were measured by SD-OCT using an automated programme. After normality tests, an independent sample t-test was used to analyse the differences in RNFL, GCL, IPL, and choroidal thickness values between the groups. Results The mean age of electronic cigarette smokers and non-smokers was 33.68 and 33.64 years, respectively. The mean smoking history was 6.6 years (range 5–8 years). Most of the participants smoked 2–5 ml of e-liquid per day (52%), while 36% smoked more than 5 ml and 12% smoked less than 2 ml per day. The mean intraocular pressure in the electronic cigarette smoker group was 15.0 mmHg, while the non-smoker group was 15.32 mmHg. The mean axial length in the electronic cigarette smoker group and non-smoker group was 23.36 and 23.63 mm, respectively. No significant difference was observed regarding RNFL, GCL, IPL or choroidal thickness between both groups. Conclusion The thickness of the RNFL, GCL, IPL, and choroid was found to be similar in both the healthy electronic cigarette smokers and non-smokers groups.

The Macular Pigment Optical Density (MPOD) Decrease in Chinese Primary Angle Closure Glaucoma Using the One-Wavelength Reflectometry Method

Purpose The objective of this study was to observe the macular pigment optical density (MPOD) and the relationship between MPOD and retinal thickness in Chinese primary angle-closure glaucoma (PACG) patients by the one-wavelength reflectometry method. Methods This study was a prospective comparative observational study, including 39 eyes from 39 PACG patients (15 men and 24 women, mean age 61.89 ± 12.30) and 41 eyes from 41 controls (20 men and 21 women, mean age 63.24 ± 14.02). We measured the MPOD 7-degree area by the one-wavelength reflectometry method and analyzed both the max and mean optical density (OD). The central retinal thickness (CRT) and the total thickness of the macular ganglion cell layer (GCL), and inner plexiform layer (IPL)were measured by spectral-domain-optical coherence tomography (SD-OCT). Statistical methods such as Shapiro–Wilk test, Fisher’s exact test, chi-square test, two independent samples test and Spearman’s correlation coefficient were used to observe the differences in the MPOD between normal subjects and PACG patients and the correlation between the MPOD and retinal thickness. Results The max optical density (Max OD) (PACG group: 0.302 ± 0.067d.u, control group: 0.372 ± 0.059d.u., p < .001) and mean optical density (Mean OD) (PACG group: 0.124 ± 0.035d.u., control group: 0.141 ± 0.028d.u., p < 0.05) were significantly reduced in PACG patients compared with control subjects. Significant decreases in GCL + IPL thickness (PACG group: 74.71 ± 39.56 μm, control group:113.61 ± 8.14 μm, p < 0.001) and CRT (PACG group: 254.49 ± 41.47 μm, control group:329.10 ± 18.57 μm, p < 0.001) were also observed in PACG eyes. There was no statistically significant correlation between the MPOD and GCL + IPL thickness (p = .639, p = .828). Conclusions MPOD was significantly lower in Chinese PACG patients than in the control group, potentially due to thinning of the GCL + IPL thickness. This study provides insights for the pathophysiology, assessment of PACG and potential guidance for lifestyle modifications.

Sustained Retinal Defocus Increases the Effect of Induced Myopia on the Retinal Astrocyte Template.

The aim of this article is to describe sustained myopic eye growth's effect on astrocyte cellular distribution and its association with inner retinal layer thicknesses. Astrocyte density and distribution, retinal nerve fiber layer (RNFL), ganglion cell layer, and inner plexiform layer (IPL) thicknesses were assessed using immunochemistry and spectral-domain optical coherence tomography on seventeen common marmoset retinas (Callithrix jacchus): six induced with myopia from 2 to 6 months of age (6-month-old myopes), three induced with myopia from 2 to 12 months of age (12-month-old myopes), five age-matched 6-month-old controls, and three age-matched 12-month-old controls. Untreated marmoset eyes grew normally, and both RNFL and IPL thicknesses did not change with age, with astrocyte numbers correlating to RNFL and IPL thicknesses in both control age groups. Myopic marmosets did not follow this trend and, instead, exhibited decreased astrocyte density, increased GFAP+ spatial coverage, and thinner RNFL and IPL, all of which worsened over time. Myopic changes in astrocyte density, GFAP+ spatial coverage and inner retinal layer thicknesses suggest astrocyte template reorganization during myopia development and progression which increased over time. Whether or not these changes are constructive or destructive to the retina still remains to be assessed.

Vascularized foveal zone: prevalence and structural characteristics

This study was performed to assess the prevalence of the vascularized foveal zone, including macular-foveal capillaries (MFC) and congenital retinal macrovessels (CRM), and to analyze the structural characteristics of the macular area in patients with MFC. The first phase of the study evaluated the prevalence of MFC and CRM. Optical coherence tomography angiography (OCT-A) was performed, and OCT-A images of the foveal avascular zone were analyzed. In the second phase, two groups were formed: the MFC group (12 eyes, 9 patients, mean age 43.8±10.7 years) and the control group (18 eyes, 17 patients, mean age 43.0±11.8 years). A comparative analysis was performed assessing central retinal thickness (CRT), thickness of retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), and foveal pit depth. MFCs were detected in 45 eyes from a total sample of 1031 eyes of 536 patients. The presence of CRM was recorded in three eyes of three patients. RNFL thickness was significantly higher in the MFC group in the inferior parafoveal sector (26.50 [26.00; 29.50] and 24.50 [21.75; 26.50] μm; p=0.022) and in the foveal zone (15.50 [14.00; 16.00] and 12.00 [11.00; 14.00] μm; p=0.017). Additionally, patients with MFC had a higher thickness of GCL and IPL in the fovea, inferior, nasal, and temporal parafoveal sectors. The depth of the foveal pit was significantly lower in the MFC group compared to the control group (83.0 [77.4; 101.6] and 128.0 [107.5; 147.05] μm; p=0.001). The prevalence of MFC was 4.36% (calculated per number of eyes), while the prevalence of CRM - 0.29%. The macular area in patients with MFC had increased thickness of the inner retinal layers and decreased depth of the foveal pit, suggesting potential disruption in the natural process of ganglion cell migration and apoptosis during embryogenesis.

Mendelian randomization reveals association between retinal thickness and non-motor symptoms of Parkinson’s disease

Retinal thickness is related to Parkinson’s disease (PD), but its association with the severity of PD is still unclear. We conducted a Mendelian randomized (MR) study to explore the association between retinal thickness and PD. For the two-sample MR analysis, the summary statistics obtained from genome-wide association studies on the thickness of Retinal nerve fiber layer (RNFL) and ganglion cell inner plexiform layer (GCIPL) were employed as exposure, while the summary statistics associated with PD were used as the outcome. The primary approach utilized was inverse variance weighted. To correct for multiple testing, the false discovery rate (FDR) was employed. For sensitivity analysis, an array of robust MR methods was utilized. We found genetically predicted significant association between reduced RNFL thickness and a reduced risk of constipation in PD (odds ratio [OR] = 0.854, 95% confidence interval [CI] (0.782, 0.933), P < 0.001, FDR-corrected P = 0.018). Genetically predicted reduced RNFL thickness was associated with a reduced Unified Parkinson’s Disease Rating Scale total score (β = −0.042, 95% CI (−0.079, 0.005), P = 0.025), and reduced GCIPL thickness was associated with a lower risk of constipation (OR = 0.901, 95% CI (0.821, 0.988), P = 0.027) but a higher risk of depression (OR = 1.103, 95% CI (1.016, 1.198), P = 0.020), insomnia (OR = 1.090, 95% CI (1.013, 1.172), P = 0.021), and rapid eye movement sleep behaviour disorder (RBD) (OR = 1.198, 95% CI (1.061, 1.352), P = 0.003). In conclusion, we identify an association between retinal thickness and non-motor symptoms (constipation, depression, insomnia and RBD) in PD, highlighting the potential of retinal thickness as a biomarker for PD nonmotor symptoms.

Reduction in Retinal Ganglion Cell Layer, Inner Plexiform Layer, and Choroidal Thickness in Children With Autism Spectrum Disorder.

The aim of this study was to evaluate the retinal nerve fiber layer (RNFL), choroidal layer, inner plexiform layer (IPL), and ganglion cell layer (GCL) in patients with autism spectrum disorder (ASD). In this study, we measured the thickness of the RNFL, GCL, IPL, and choroidal thickness using a spectral optical coherence tomography (OCT) device and we compared the results between the children diagnosed with ASD and healthy controls. Correlation between the Childhood Autism Rating Scale (CARS) and the OCT data was evaluated. Both ASD and control group consisted of 40 subjects (30 males and 10 females). Of the children in the ASD group, 29 had normal intelligence and 11 had mild intellectual disability (MID). The mean age of patients in the ASD group and control groups were 9.77 ± 3.37 years and 9.85 ± 3.97 years (p = 0.928). There was a statistically significant difference between the ASD group and the control group in the nasal and nasal-superior sectors of the RNFL layers in the left eye when all the lower layers of RNFL were assessed. In both eyes, the children with ASD had considerably lower mean choroidal thicknesses than the controls. When compared to the controls, the GCL and IPL volumes in the individuals with ASD were considerably lower in both eyes. Compared to the MID group, the left GCL volume of the nasal-inferior group was noticeably higher. A significant correlation was found between CARS scores and left GCL left IPL. In contrast to RNFL in the ASD group, significant reductions in IPL, GCL, and choroidal thickness were observed in both eyes. It is thought that GCL may be a much more important biomarker than RNFL in terms of representing the structural deterioration in the brain. In addition, these results may form the basis for a new perspective on the use of OCT for the diagnosis and clinical course of autism.

Changes in Macular Thickness and Microvasculature in Koreans with Early Parkinson’s Disease

Purpose: To investigate the thickness of the nerve fiber layer-ganglion cell inner plexiform layer (NFL-GCIPL) complex and microvascular macular changes in Korean patients with early Parkinson’s disease using optical coherence tomography (OCT) and OCT angiography (OCTA).Methods: Forty-three eyes of 22 patients with early Parkinson’s disease were included. A control group of 20 patients (40 eyes) was also recruited. The thickness of the NFL-GCIPL macular complex was measured using OCT, and the densities of the superficial and deep macular retinal vessels were evaluated via OCTA in all subjects.Results: The NFL-GCIPL thicknesses of the superior, inferior, temporal, and nasal sectors were 94.70 ± 9.35, 93.32 ± 9.16, 90.18 ± 6.32, and 93.11 ± 8.75 μm in the control group and 92.05 ± 4.96, 91.32 ± 7.48, 84.74 ± 6.82, and 91.32 ± 7.47 μm in the Parkinson’s disease group, respectively; all thicknesses were significantly greater in the control group. The superficial and deep retinal vessel densities did not differ between the two groups.Conclusions: Neurodegenerative macular changes are more obvious than microvascular changes in patients with early Parkinson’s disease. Such neurodegenerative changes should be further evaluated in future cohort studies.

Differences in Retinal and Choroidal Microvasculature and Structure in Dementia With Lewy Bodies Compared With Normal Cognition.

Purpose: To evaluate the retinal and choroidal microvasculature and structure in individuals with dementia with Lewy bodies (DLB) compared with controls with normal cognition using optical coherence tomography (OCT) and OCT angiography (OCTA). Methods: An institutional review board-approved cross-sectional comparison of patients with DLB and cognitively normal controls was performed. The Cirrus HD-OCT 5000 with AngioPlex (Carl Zeiss Meditec) was used to obtain OCT and OCTA images. Results: Thirty-four eyes of 18 patients with DLB and 85 eyes of 48 cognitively normal patients were analyzed. The average capillary perfusion density (CPD) was higher in the DLB group than in the control group (P = .005). The average capillary flux index (CFI) and ganglion cell inner-plexiform layer (GC-IPL) thickness were lower in the DLB group than in the control group (P = .016 and P = .040, respectively). Conclusions: Patients with DLB had an increased peripapillary CPD, decreased peripapillary CFI, and attenuated GC-IPL thickness compared with those with normal cognition.

Retinal clues for selective neuronal loss in multiple sclerosis.

The relationship between the cell body layer and the dendritic network layer of the retina and cognitive performance (CP) in MS patients has not been examined separately. The objective of this study is to predict cognitive impairment (CI) in RRMS patients and to examine the relationship between CP and ganglion cell layer (GCL), inner plexiform layer (IPL), and GCL divided by IPL (GCL/IPL). Ophthalmological evaluation, retinal segmentation, and Symbol Digit Modalities Test (SDMT) were performed on 102 RRMS patients and 54 healthy subjects. The relationships of GCL, IPL, and GCL/IPL with CP in eyes without a history of optic neuritis were investigated using Spearman's correlation. Models were created by accepting 1 standard deviation less of the SDMT mean of the control group as the limit for CI. The cutoff value of the GCL/IPL variable that could predict CI was calculated by ROC analysis, and the ability to accurately predict CI was tested with binary logistic regression. No correlation was found between OCT parameters and CP in healthy subjects. Correlation was found between GCL thickness and GCL/IPL variable and CP in RRMS patients (r=0.235, r=0.667 respectively). A GCL/IPL value of 1.255 was able to identify CI with 81.8% sensitivity and 75.9% specificity (AUC=0.844, LR=3.38) and predicted CI with 74.5% accuracy (Nagelkerke R2=0.439). In RRMS patients, the IPL thickness is unrelated to CP. Therewithal, the GCL/IPL-CP relationship is stronger than the GCL-CP relationship and GCL/IPL can predict CI.

Association of macular pigment optical density with retinal layer thicknesses in eyes with and without manifest primary open-angle glaucoma

ObjectiveTo investigate associations between baseline macular pigment optical density (MPOD) and retinal layer thicknesses in eyes with and without manifest primary open-angle glaucoma (POAG) in the Carotenoids in Age-Related Eye...

Corneal parameters, ocular biometers, and retinal and choroidal thickness in acromegaly patients

BackgroundTo compare ocular findings of acromegaly patients with healthy individuals and investigate the relation of serum levels of insulin-like growth factor (IGF-1) along with growth hormone (GH) and pituitary tumor (adenoma) dimensions (TD) with specific ocular parameters. MethodsThe ocular parameters of acromegaly patients (n = 38) were compared with those of healthy subjects (n = 36). These parameters were intraocular pressure, keratometric (K1–K2) values, central corneal thickness (CCT), total axial length along with anterior chamber-lens-vitreous length, retinal nerve fiber layer (RNFL) thickness, central foveal thickness (CFT), choroidal thickness (CT), ganglion cell layer thickness (GCLT), and inner plexiform layer thickness (IPLT). Also investigated was whether there was a correlation between disease duration, TD, GH, IGF-I, CCT, RNFL, CFT, GCLT, IPLT, and CT. ResultsThe lens length of the acromegaly group was increased (p = 0.014). GH and IGF-1 levels were positively correlated with CT and CCT, respectively (p = 0.041, r = 0.343) (p = 0.03, r = 0.347). Analysis of TD also found a highly negative correlation with the mean RNFL thickness of the acromegaly patients (p < 0.01, r = -0.603). The mean value of the inner parts of GCLT and IPLT was negatively correlated with TD (p = 0.041, r = -0.343 and p = 0.025, r = -0.379, respectively). ConclusionSerum IGF-1 and GH levels might be determinant factors in CCT and CT, respectively. The pituitary adenoma size increasing may be prone to lead RNFL, ganglion cell layer, inner plexiform layer thinning. Increased lens thickness was found in the acromegaly group.

Is the ganglion cell layer thickness to macular thickness ratio a new biomarker for multiple sclerosis?

Ganglion cell layer thickness (GCLT)-to-total macular thickness (MT) is a new parameter that has not been studied in multiple sclerosis (MS) before. The current study aims to reveal the status of the GCLT-to-MT ratio in MS and its role in supporting the diagnosis of MS. In this retrospective and cross sectional study, the medical records of the MS patients between January 2016 and December 2021 were reviewed. Age-sex matched healthy control group was generated. Demographic and clinical data recorded. All participants were examined using a spectral-domain optic coherence tomography (OCT) device. Retinal layers, choroidal thickness (CT) was recorded. GCLT-to-MT ratio was calculated. A total of 74 eyes of 37 MS (9 male,28 female) patients and 82 eyes of 41 control (13 male, 28 female) were included in the study. The mean age was 37 ± 9.0 (years) in MS group. The MS patients and the control group were compared in terms of OCT parameters, CT was thicker at all regions in MS patients (p < 0.001). Macular thickness, GCLT, and inner plexiform layer thickness (IPLT) were thinner than the control group (p < 0.05). For distinguishing MS patients from healthy subjects, AUROC values for central GCLT/MT, temporal GCLT/MT, superior GCLT/MT, nasal GCLT/MT, and inferior GCLT/MT were 0.717, 0.689, 0.694, 0.733, and 0.740, respectively. In conclusion MT, GCLT, and IPLT thickness were thinner in MS patients, regardless of optic neuritis. The AUROC values of GCLT/MT were high and GCLT/MT ratio may be a helpful modality in demonstrating retinal neurodegeneration in MS patients.

Regional Analysis of Inner Retinal Layer Changes in Multiple Sclerosis with and without Optic Neuritis.

The study aimed to investigate inner retinal changes in multiple sclerosis (MS) patients by comparing them with healthy controls. The study also aimed to assess regional differences of inner retinal layer involvement in eyes with and without optic neuritis (ON). This retrospective, cross-sectional study consisted of 141 eyes of 74 relapsing-remitting MS patients and 80 eyes of 40 healthy controls. The study group was separated into two subgroups according to the presence of ON history. Peripapillary retinal nerve fiber layer (pRNFL) thickness, total macular thickness, and thicknesses of the macular retinal nerve fiber layer (mRNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), and inner nuclear layer were compared between the MS and healthy control groups and between eyes with and without ON history. Mean pRNFL, total macular, mRNFL, GCL, and IPL thicknesses were significantly thinner in the MS group than in the control group (p<0.001) and in eyes with ON compared to those without ON (p<0.05). Comparison of inner retinal layer thicknesses in the inner 3-mm ring subfields of the ETDRS grid revealed significant thinning in all subfields of the GCL and IPL of eyes with ON (p<0.05). The inferior subfield demonstrated the highest difference. The study demonstrated that GCL and IPL thinning is a robust and reliable biomarker in all MS patients. The thinning was significantly greater in eyes with ON than in eyes without ON. The study also documented that the inferior region showed significantly greater GCL and IPL thinning in eyes with previous ON attacks.

Impact of anti-VEGF therapy on distinctive retina layers in patients with macular edema secondary to branch retinal vein occlusion

BackgroundTo explore the impact of anti-vascular epithelial growth factor (ant-VEGF) on the thickness of each retinal layer in patients with macular edema (ME) secondary to the branch retinal vein occlusion (BRVO).MethodsThis retrospective study included patients with ME secondary to monocular BRVO who received anti-VEGF therapy in Ningxia Eye Hospital between January-December 2020.ResultsForty-three patients (25 males) were included, with 31 showed > 25% reduction in central retinal thickness (CRT) after anti-VEGF therapy (response group), and the others showed a ≤25% reduction in CRT (no-response group). The response group showed significantly smaller mean changes in the ganglion cell layer (GCL) (after 2 months) and inner plexiform layer (IPL) (after 1, 2, and 3 months) and significantly greater mean changes in the inner nuclear layer (INL) (after 2 and 3 months), outer plexiform layer (OPL) (after 3 months), outer nuclear layer (ONL) (after 2 and 3 months), and CRT (after 1 and 2 months) (all P < 0.05) as compared to the no-response group. The mean change in the thickness of each retinal layer IPL (P = 0.006) between the two groups was significantly different after controlling for a time and with a significant time trend (P < 0.001). Additionally, patients in the response group were more likely to have an improvement in IPL (43.68 ± 6.01 at 1 month and 41.52 ± 5.45 at 2 months vs. 39.9 ± 6.86 at baseline) after anti-VEGF therapy, while those in no response group might show improvement in GCL (45.75 ± 8.24 at 1 month, 40.00 ± 8.92 at 2 months, and 38.83 ± 9.93 at 3 months vs. 49.67 ± 6.83 at baseline).ConclusionsAnti-VEGF therapy might help restore the retinal structure and function in patients with ME secondary to BRVO, and those who have a response after anti-VEGF therapy are more likely to improve IPL, while those having no response might show improvement in GCL.

Comparison of Ganglion Cell Layer and Inner Plexiform Layer Rates of Change in Suspected and Established Glaucoma

We compared ganglion cell layer (GCL) and inner plexiform layer (IPL) rates of change (RoC) in patients with glaucoma suspect (GS) and established glaucoma (EG) to test the hypothesis that IPL thickness changes would occur earlier than GCL changes in eyes with early damage. Prospective, cohort study. A total of 64 GS eyes (46 patients) and 112 EG eyes (112 patients) with ≥2 years of follow-up and ≥3 macular optical coherence tomography scans were included. GCL and IPL superpixel thickness measurements were exported. A Bayesian hierarchical model with random intercepts/slopes and random residual variances was fitted to estimate RoC in individual superpixels. Normalized RoC and proportions of superpixels with significantly negative and positive GCL and IPL RoC were compared within the groups. The average (SD) follow-up time and number of scans were 3.5 (0.7) years and 4.2 (1.0), respectively, in the GS group and 3.6 (0.4) years and 7.3 (1.1) in the EG group. Mean (SD) normalized RoC was faster for GCL than IPL (-0.69 [0.05] vs -0.33 [0.04]) in the GS group, whereas it was faster for IPL (-0.47 [0.03] vs -0.28 [0.02]) in EG eyes. GCL RoC were significantly negative in 24 of 36 superpixels compared with 8 of 36 for IPL (P < .001) in GS eyes. In the EG group, 23 of 36 superpixels had significant negative IPL RoC compared with 13 of 36 superpixels for GCL (P=.006). GCL thickness is more likely to demonstrate change over time compared with IPL in glaucoma suspects. There is no evidence of preferential IPL thinning in eyes with suspected early glaucoma damage.

Retinal development and the expression profiles of opsin genes during larval development in Takifugu rubripes.

The light-sensitive capacity of fish larvae is determined by the structure of the retina and the opsins expressed in the retinal and nonretinal photoreceptors. In this study, the retinal structure and expression of opsin genes during the early developmental stage of Takifugu rubripes larvae were investigated. Histological examination showed that at 1 days after hatching (dah), seven layers were observed in the retina of T. rubripes larva, including the pigment epithelial layer [retinal pigment epithelium layer (RPE)], photoreceptor layer (PRos/is), outer nuclear layer (ONL), outer plexiform layer (OPL), inner nuclear layer (INL), inner plexiform layer (IPL) and ganglion cell layer (GCL). At 2dah, optic fibre layer (OFL) can be observed, and all eight layers were visible in the retina. By measuring the thickness of each layer, opposing developmental trends were found in the thickness of ONL, OPL, INL, IPL, GCL and OFL. The nuclear density of ONL, INL and GCL and the ratios of ONL/INL, ONL/GCL and INL/GCL were also measured and the ratio of ONL/GCL ranged from 1.9 at 2dah to 3.4 at 8dah and no significant difference was observed between the different developmental stages (P > 0.05). No significant difference was observed for the INL/GCL ratio between the different developmental stages, which ranged from 1.2 at 2dah to 2.0 at 18 dah (P > 0.05). The results of quantitative real-time polymerase chain reaction (PCR) showed that the expression of RH1, LWS, RH2-1, RH2-2, SWS2, rod opsin, opsin3 and opsin5 could be detected from 1dah. These results suggest that the well-developed retina and early expression of the opsins of T. rubripes during the period of transition from endogenous to mixed feeding might be critical for vision-based survival skills during the early life stages after hatching.

Evaluation of the segmented inner retinal layers in exfoliation glaucoma.

To investigate the macular spectral domain optical coherence tomography (SD-OCT) measurements of the segmented inner retinal layers in patients with exfoliation syndrome (XFS), exfoliation glaucoma (XFG). This prospective cross-sectional study included 28 eyes with XFS, 47 eyes with XFG, and 29 healthy controls. Thickness of the inner retinal layers, including retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), and inner plexiform layer (IPL) was obtained from the horizontal SD-OCT scans. Functional correlation of structural parameters was analyzed using the mean sensitivity (MS) values on 10-2 visual fields. The RNFL, GCL, and IPL were thinnest in eyes with XFG. Among these retinal layers, IPL was significantly thinner in eyes with XFS than healthy controls (p = 0.02) and the IPL thickness was significantly correlated with the corresponding MS scores on 10-2 visual fields (r = 0.492, p = 0.02) in eyes with XFS. Neither GCL nor RNFL thickness values demonstrated significant correlations with functional parameters in eyes with XFS (r = 0.377, p = 0.08; r = 0.212, p = 0.34). In eyes with XFG, the IPL thickness correlated with the visual field MS scores (r = 0.572, p = 0.0007), similar to the correlation of GCL (r = 0.585, p = 0.0005) thickness with visual field scores. Segmented analysis of the macular IPL thickness presented a significant correlation with the 10-2 visual field scores not only in eyes with XFG but also in eyes with XFS. With respect to early dendritic/synaptic alterations in animal models, larger and longitudinal studies are encouraged to determine the predictive value of the IPL thickness for conversion of XFS to XFG.

A CLINICAL STUDY OF RETINAL GANGLION CELL LAYER AND RETINAL NERVE FIBER LAYER CHANGES IN COGNITIVE DYSFUNCTION IN ELDERLY PATIENTS ATTENDING PSYCHIATRY OPD IN A TERTIARY HOSPITAL IN NORTHEAST BIHAR

Objective: The objective of this study was to study and compare retinal nerve fiber layer (RNFL) changes and retinal ganglion cell layer (GCL) changes in different quadrants of the eye in elderly patients (60 years or more) with cognitive impairment. Methods: Study conducted in the Department of Ophthalmology and Psychiatry in M.G.M. Medical College and L.S.K. Hospital Kishanganj, Bihar. It was a cross-sectional study. Random sampling among elderly patients with cognitive impairment attending Psychiatry OPD. A total 50 patients (32 cases+18 control). Thirty-two cases with mild cognitive impairment (MCI) having mini-mental state examination (MMSE) score &lt;24 and 12 controls with normal cognition (NC) having MMSE score &gt;30 were enrolled in this study. Mini-mental status examination and montreal cognitive assessment-for selection of cognitive impairment patients. Optical coherence tomography (OCT) to compare changes in the retinal GCL and RNFL in different eye quadrants. Results: The observation of the present study reveals mean thickness of the GCL and the inner plexiform layer (IPL) was significantly higher among healthy controls in both right and left eyes compared to the case group (p=0.05 and 0.008, respectively). The comparison of GCL and IPL thickness in the inferior temporal quadrant between case and control group. The observation of the present study reveals that the mean thickness of the GCL and IPL in the inferior temporal quadrant was comparable between healthy controls and the case group in the right eyes (p=0.606), and it was significantly higher among healthy controls compared to case group in the left eyes (p=0.05). Conclusion: As a result, it is recommended that all patients over the age of 60 have a routine retinal evaluation with OCT to detect early neurodegenerative alterations for the early diagnosis and management. According to our study, the sensitivity of GCL+IPL to distinguish MCI from controls was often higher than that of RNFL.

Machine learning based on Optical Coherence Tomography images as a diagnostic tool for Alzheimer's disease.

We mainly evaluate retinal alterations in Alzheimer's disease (AD) patients, investigate the associations between retinal changes with AD biomarkers, and explore an optimal machine learning (ML) model for AD diagnosis based on retinal thickness. A total of 159 AD patients and 299 healthy controls were enrolled. The retinal parameters of each participant were measured using optical coherence tomography (OCT). Additionally, cognitive impairment severity, brain atrophy, and cerebrospinal fluid (CSF) biomarkers were measured in AD patients. AD patients demonstrated a significant decrease in the average, superior, and inferior quadrant peripapillary retinal nerve fiber layer, macular retinal nerve fiber layer, ganglion cell layer (GCL), inner plexiform layer (IPL) thicknesses, as well as total macular volume (TMV) (all p < 0.05). Moreover, TMV was positively associated with Mini-Mental State Examination and Montreal Cognitive Assessment scores, IPL thickness was correlated negatively with the medial temporal lobe atrophy score, and the GCL thickness was positively correlated with CSF Aβ42 /Aβ40 and negatively associated with p-tau level. Based on the significantly decreased OCT variables between both groups, the XGBoost algorithm exhibited the best diagnostic performance for AD, whose four references, including accuracy, area under the curve, f1 score, and recall, ranged from 0.69 to 0.74. Moreover, the macular retinal thickness exhibited an absolute superiority for AD diagnosis compared with other enrolled variables in all ML models. We identified the retinal alterations in AD patients and found that macular thickness and volume were associated with AD severity and biomarkers. Furthermore, we confirmed that OCT combined with ML could serve as a potential diagnostic tool for AD.

The effects of hyperbaric oxygen therapy on retinal layers in healthy eyes

Purpose: The aim of our study is to investigate the effects of hyperbaric oxygen (HBO2) therapy on retinal layers in healthy eyes. Method: Thirty patients who were taken to outpatient HBO2 for any indication were included in the study. All patients underwent 10 sessions of HBO2; 20 healthy patients were taken as the control group. We used the spectral-domain optical coherence tomography (SD-OCT) to obtain automated measurements of thickness for each retinal layer – i.e., the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL) and retinal pigment epithelium (RPE) – and to conduct foveal (central 1 mm), inner-ring (parafoveal 1 to 3mm), and outer-ring (perifoveal 3 to 6mm) retinal layer measurements. Retinal OCT scans were performed before HBO2, after the first and 10th sessions. All retinal layer thicknesses were assessed with SD-OCT software system and compared between each visit. Retinal thicknesses were calculated in the central, inner ring and outer ring subfields (nine quadrants). Results: In SD-OCT measurements, there were no statistically significant difference before HBO2, after the first and 10th sessions in terms of foveal, inner-ring and outer-ring thickness of RNFL, GCL, IPL, INL, OPL, ONL and RPE. Conclusions: Our study demonstrated that there was no change in the thickness of the retinal layers after the first and 10th sessions in healthy eyes.