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Optical coherence tomography (OCT) is a non-invasive imaging technique in the field of ophthalmology that has been increasingly recognized for its capability to identify potential biomarkers in neurodegenerative processes. While the retinal nerve fiber layer (RNFL) has been vastly explored, this review focuses on the ganglion cell layer (GCL), highlighting its relevance and potential advantages in the diagnostic approach and monitoring of neurodegenerative conditions. In the present review we explore the role of GCL changes detected by OCT in Alzheimer’s disease (AD), Parkinson’s disease (PD), and multiple sclerosis (MS). We focus on these conditions due to their prevalence and substantial social impact among neurodegenerative diseases. We summarize key findings on the changes in the GCL and their correlations with disease progression and severity. Moreover, we highlight GCL measurements in the context of a multidisciplinary diagnostic approach, and their potential in adapting tailored therapeutic strategies in neurodegenerative disease management. Challenges such as methodological variability in OCT measurements, automatic instrumental output parameters, the limitations of GCL as a standalone diagnostic tool, and the impact of systemic and ocular factors are discussed. Finally, we propose that forthcoming advancements in OCT technology, integration with other biomarkers, and longitudinal studies will likely further enhance the understanding of GCL changes over time.

PurposeTo investigate the effect of posterior ocular hemodynamics on the retinal nerve fiber layer (RNFL), choroid thickness (CT) and central macular thickness (CMT) in patients with obstructive sleep apnea syndrome (OSAS) and to reveal the association with glaucomatous optic neuropathy.MethodsThe research was planned as a prospective, randomized study. The ophthalmic, retinal and posterior ciliary artery pulsatile index (PI) and resistive index (RI) were measured by colored Doppler sonography. RNFL thickness, CMT and CT were then measured by spectral-domain optical coherence tomography.ResultsSixty subjects were divided into four groups—mild, moderate and severe OSAS and a control group. There were 16 subjects in the control group, 14 in the mild OSAS group, 15 in the moderate OSAS group and 15 in the severe OSAS group. Ophthalmic artery and central retinal artery PI and RI values of the OSAS patients did not show statistically significant difference than those of the control group, but posterior ciliary artery (PCA) PI and RI values were significantly higher. In addition, mean, superior and inferior RNFL thickness values were significantly lower than those in the control group. Moreover, the glaucoma prevalence of the OSAS patients in this study was 6.8% and all of these patients were in the severe OSAS group.ConclusionPI and RI values of the PCA, which supplies the optic nerve, show a linear increase as the apnea hypoxia index values in OSAS. As the grade of OSAS improves, this situation leads to a more serious ischemic optic neuropathy. Furthermore, the prevalence of glaucoma in this study is found to be higher in the severe OSAS group.

Purpose To compare the effects of selective α-1 adrenoceptor antagonists on subfoveal choroidal thickness (SFCT) and pupil diameter size (PDS). Methods This prospective study included 87 patients diagnosed with benign prostatic hyperplasia who were treated with tamsulosin hydrochloride ( n  = 41) or silodosin ( n  = 46). SFCT measurements were obtained using spectral domain optic coherence tomography (SD-OCT), and PDS measurements were obtained under mesopic, photopic and scotopic conditions using a photography-based topography system. SFCT and PDS were evaluated at baseline and 3-, 6- and 12-mo follow-ups. Results The initial mean SFCT was 270.53 ± 21.48 µm in tamsulosin group and 271.95 ± 24. 73 in silodosin group ( P  = 0.078). There was no statistically significant change in SFCT at the 3-mo visit. At the 6-mo follow-up, the mean SFCT was 281.34 ± 22.09 µm in tamsulosin group and 272.5 ± 22.4 µm in silodosin group. At the 12th month, the mean SFCT in tamsulosin group was 290.80 ± 17.27 µm, and it was 270.80 ± 13.14 µm in silodosin group. There was statistically significant difference in at 6th and 12-mo visits ( P  = 0.014 and P  = 0.00). During the follow-up, both drugs induced a similar significant decrease in PDS under all conditions. Conclusions Tamsulosin hydrochloride caused a significant increase in SFCT. In contrast, SFCT did not increase in silodosin group. The decreases in PDS achieved using both drugs were similar. This should be kept in mind when choroidal disease and its response to treatment are followed by CT imaging.

Objectives: Multiple Sclerosis (MS) frequently causes injury to the anterior visual pathway (AVP), impairing quality of life due to visual dysfunction. Development of biomarkers in MS is a high priority and both low-contrast visual acuity (LCVA) and time-domain optical coherence tomography (TD-OCT) have been proposed as candidates for this purpose. We sought to assess whether psychophysical assessments of color vision are similarly correlated with structural measures of AVP injury, and therefore augment measures of visual disability in MS. Methods: We studied the association between high-contrast visual acuity (HCVA), LCVA, color vision (Hardy–Rand–Rittler plates (HRR) and Lanthony D15 tests) and OCT, using both high-resolution spectral-domain OCT (SD-OCT; Spectralis, Heidelberg Engineering, Germany) and TD-OCT (Stratus, Carl Zeiss, US) in a cohort of 213 MS patients (52 with previous optic neuritis) and 47 matched controls in a cross-sectional study. Results: We found that MS patients have impairments in HCVA and LCVA (p < 0.001) but that they suffer from even more profound abnormalities in color discrimination (p < 0.0001). We found strong correlation between color vision and SD-OCT measures of retinal nerve fiber layer (RNFL) thickness (average RNFL, r = 0.594, p < 0.001) and papillomacular bundle thickness (r = −0.565, p < 0.001). The correlation between OCT scores and functional visual impairments of all types was much stronger for SD-OCT than for TD-OCT. Conclusion: Our results indicate that color vision is highly correlated with these OCT scores when compared with traditional measures of visual acuity. Also we found that SD-OCT is superior to TD-OCT for detecting anterior visual pathway damage in MS. This makes both color-visual measures and SD-OCT strong candidate biomarkers of disease progression.

Objectives: To evaluate the vascular changes of idiopathic macular telangiectasia type 2 (MacTel 2) patients with optical coherence tomography angiography (OCTA) and correlate these changes with the findings of spectral domain optical coherence tomography (SD-OCT). Materials and Methods: Simultaneous SD-OCT and OCTA images of 10 eyes of 6 patients who were diagnosed as MacTel 2 in Ankara University Faculty of Medicine, Department of Ophthalmology were obtained and graded according to the OCTA grading system for MacTel 2. Results: Ten eyes of 6 patients were included. Four (66%) patients were female and 2 (34%) were male. The disease was grade 0 in 2 eyes, grade 1 in 2 eyes, grade 2 in 3 eyes, grade 3 in 1 eye, grade 4 in 1 eye, and grade 5 in 1 eye. The most common findings in grade 1, 2, and 3 non-proliferative disease were thinning of the outer retinal layers, presence of intraretinal hyporeflective layers and inner limiting membrane draping. In cases with subretinal choroidal neovascularisation (CNV) in OCTA, CNV or CNV scar was present in the B-scan SD-OCT images. In a case in which OCT was within normal limits, vascular changes consistent with grade 1 disease were observed in OCTA. On the contrary, 2 patients with significant foveal atrophy and macular hole in B-scan showed changes of early disease in OCTA. In some of the eyes, OCTA revealed an intact superficial vascular layer despite visible changes in the deep layer and the presence of neovascularisation. Conclusion: OCTA yields findings which are important for understanding the pathogenesis of the disease and providing better follow-up. Contrary to fundus fluorescein angiography, changes in the deep arterial plexus in the early disease and CNV can be clearly observed with OCTA. To achieve the best results in clinical practice, en face flow maps should be evaluated together with B-scan SD-OCT images. Keywords: Macular telangiectasia type-2, optic coherence tomography angiography, spectral domain optic coherence tomography

Background In 2014, Pang et al. reported three cases with vitelliform submaculopathy as a preceding lesion of primary intraocular lymphoma (PIOL). Here, we report a case with an atypical presentation of PIOL who initially presented with vitelliform submaculopathy, vitreous haze and preripheral retinal focus. Case presentation A 73-year-old female initially visited another hospital with a chief complaint of acute reduced vision in the right eye. Funduscopic examination of the right eye showed a yellowish retinal lesion at the fovea with vitreous haze and retinal foci scattered in the peripheral region. Spectral-domain optic coherence tomography (SD-OCT) revealed a hyperreflective subretinal debris above the retinal pigment epithelium (RPE) at the fovea, suggesting vitelliform submaculopathy. Vitrectomy was performed to improve visualization of the retinal lesions and for examination of PIOL. Vitreous cytology was class III and cytokine analysis of vitreous fluid showed increased IL-10 and an IL-10/IL-6 ratio >1, suggesting PIOL. Thereafter, there was a sub-RPE infiltration of presumed lymphoma in the nasal retina, and PCR analysis of anterior chamber fluid indicated IgH gene rearrangement, leading to diagnosis of PIOL. Three months later, there was complete disappearance of the vitelliform submacular lesion, with resultant disruption and thinning of the outer retinal layers on SD-OCT images. Conclusions Clinicians should be aware of atypical manifestations of PIOL such as vitelliform submaculopathy and peripheral retinal foci with vitreous haze. The patient’s unusual funduscopic changes are findings that have not reported in patients with PIOL.

Medical imaging is the mainstay of clinical diagnosis and management. Optical coherence tomography (OCT) is a non-invasive imaging technology that has revolutionized the field of ophthalmology. Since its introduction, OCT has undergone significant improvements in image quality, speed, and resolution, making it an essential diagnostic tool for various ocular pathologies. OCT has not only improved the diagnosis and management of ocular diseases but has also found applications in other fields of medicine. In this manuscript, we provide a brief overview of the history of OCT, its current uses and diagnostic capabilities to assess the posterior segment of the eye, and the evolution of this technology from time-domain (TD) to spectral-domain (SD) and swept-source (SS). This brief review will also discuss the limitations, advantages, disadvantages, and future perspectives of this technology in the field of ophthalmology.

Background The aim of this study was to investigate the neuroretinal structure of patients with the lysosomal storage disease cystinosis. Methods In this retrospective cross-sectional analysis, optical coherence tomography (OCT) was used to measure the peripapillary retinal nerve fiber layer (pRNFL), the optic disc volumes, the prelaminar depth and the macular ganglion cell layer volumes (mGCL) in patients with genetically confirmed infantile nephropathic cystinosis. The same measurements were repeated in an age -and spherical equivalent (SE) matched, healthy control group. Results The cystinosis group included 40 patients (40 eyes) with a mean age of 20.6 ± 8.6 years and a SE of 0.47 ± 1.85. The healthy control group consisted of 30 patients (30 eyes) with a mean age of 20.7 ± 12.5 years and a SE of 0.47 ± 1.29. A pronounced deposition of crystals in the optic disc was observed in all cystinosis cases. Cystine crystals follow the nerve fibers in a dense, pearl-string pattern. A significantly thicker pRNFL and a higher rate of positive prelaminar depth was evident in the cystinosis group (839.7 ± 151.0 μm vs. 775.7 ± 79.6 μm, p  = 0.004). A significantly smaller mGCL volume was found in the cystinosis group as compared to normal controls (0.25 ± 0.03 mm³ vs. 0.35 ± 0.03 mm³, p  = 0.036). Conclusions Cystinosis leads to pronounced crystal accumulation in the optic disc in early stages of the disease. This accumulation occurs in concomitance with the well-described cystine crystal deposits in the cornea, which have previously been considered the foremost ocular sign of cystinosis. The pearl-string appearance of crystal deposition suggests a primarily glial localization. A significantly thicker pRNFL and a higher rate of positive prelaminar depth was observed in the OCT scans of cystinosis patients, explaining the clinical impression of a crowded optic disc. Additionally, retinal neurodegeneration was significant in patients with cystinosis if compared to healthy controls. The optic disc crowding may result from the dense deposition of cystine crystals in the optic nerve head and the GCL thinning could be due to metabolically induced ganglion cell atrophy. However, the exact reason for these changes remains to be elucidated.

Objective: To assess the sensitivity of optic coherence tomography (OCT) and visual evoked potentials (VEPs) to visual pathway abnormalities in multiple sclerosis (MS). Methods: A total of 40 MS subjects, 28 with optic neuritis (ON) at least 3 months before (bilateral in 5), underwent assessment of visual acuity, Expanded Disability Status Scale (EDSS), OCT and VEPs, the latter quantified with a 0–4 conventional score. Results: OCT and VEPs were abnormal in 36% and 56% respectively in all eyes (p=0.11), 68% and 86% in eyes with previous ON (p=0.12), and in 19% versus 40% in eyes without ON history (p=0.007). Combining VEP and OCT increased sensitivity to 89% in ON and 44% in non-ON eyes. Considering all eyes, global retinal nerve fibre layer (RNFL) thickness and VEP score were significantly correlated between them (ρ=−0.63, p<0.001) and with EDSS (RNFL: ρ=0.40, p<0.001; VEP score: ρ=0.47, p<0.001). Disease duration correlated with VEP score (ρ=0.25, p=0.025) and RNFL thickness (ρ=−0.71, p<0.001). Conclusions: In eyes without ON, VEPs were more frequently abnormal than OCT, while the two techniques showed similar sensitivity in eyes previously affected by ON. The correlation of VEPs and OCT measures with disability prompts further exploration of the two techniques as potential markers of disease burden.

AimTo determine longitudinal changes of the ganglion cell-inner plexiform layer (GC-IPL) thickness in patients with high myopia.MethodsThe subjects were divided into two groups: a high myopia group (axial length ≥26.0 mm) and a normal control group. Both groups were divided into subgroups based on age (decade): 20s, 30s, 40s and 50s. Twenty eyes were included in each subgroup. After the initial visit, GC-IPL thicknesses were measured three more times with at least a 1-year interval between examinations using spectral domain optical coherence tomography. The average GC-IPL thickness was fitted with linear mixed models.ResultsThe average GC-IPL thickness at the first visit was 78.50 ± 8.79 µm and 84.29 ± 6.12 µm in the high myopia and control groups, respectively. In both groups, the average GC-IPL thickness showed a significant change over time. The rate of GC-IPL reduction in individuals aged in their 50s, 40s, 30s and 20s with high myopia were −0.81 µm/year,–0.51 µm/year, −0.28 µm/year and −0.12 µm/year, respectively, and in controls in their 50s, 40s, 30s and 20s, they were −0.31 µm/year,–0.25 µm/year, −0.12 µm/year and −0.02 µm/year, respectively. Additionally, individuals aged in their 50s showed a statistically significant interaction between group and duration (p<0.001).ConclusionsHighly myopic eyes had thinner GC-IPL and a significantly greater reduction in GC-IPL over 3 years when compared with normal eyes. Additionally, the reduction rate of the GC-IPL thickness was greater in older patients in both groups, which was more prominent in the high myopia group.