Role of Optical Coherence Tomography in Predicting Visual Outcome after Surgery for Sellar and Supra-Sellar Tumors.

BACKGROUND: Almost one-fifth of patients undergoing surgery for sellar/supra-sellar tumors do not gain a significant improvement in their vision. Various methods have been described to predict prospective visual outcomes in them, although they lack uniformity. OBJECTIVE: The study was conducted to predict visual outcomes following surgery for sellar and supra-sellar tumors compressing the anterior optic pathway based on pre-operative optical coherence tomography (OCT) parameters. METHODS AND MATERIALS: This was a record-based observational descriptive longitudinal study done in a tertiary care center in India. Thirty-seven patients (74 eyes) diagnosed with sellar supra-sellar lesions were included in the study. Patients' ophthalmic evaluations, done pre-operatively and 3 months post-operatively, were reviewed. Spectral-domain OCT and segmentation were done using the automated segmentation technology of Spectralis software. The thickness of the respective layers was measured. RESULTS AND CONCLUSIONS: The mean age of the study population was 42.68 years. Eyes with a pre-operative visual acuity component of VIS (visual impairment score) ≤61, pre-operative ganglion cell layer thickness ≥26.31 um, a pre-operative inner plexiform layer thickness of ≥25.69 um, a pre-operative ganglion cell inner plexiform layer thickness of 52.00 um, pre-operative ganglion cell complex thickness ≥84.47 µm, and a pre-operative inner retinal layer thickness of ≥205.25 µm were more likely to have an improved visual outcome. Eyes with a pre-operative duration of visual symptoms of ≥15 months, VIS ≥126.50, a pre-operative decimal visual acuity of <0.035, a pre-operative visual field index of ≤8%, a pre-operative macular thickness of ≤287.06 um, a pre-operative macular RNFL (retinal nerve fiber layer) thickness ≤66.00 µm, and a pre-operative peri-papillary RNFL thickness ≤64.62 µm were unlikely to have visual improvement.

Generation and characterization of retinal pigment epithelium from patient iPSC line to model oculocutaneous albinism (OCA)1A disease.

Oculocutaneous albinism (OCA) is characterized by reduced melanin biosynthesis affecting the retina, thus impairing visual function. The disease pathology of OCA is poorly understood at the cellular level due to unavailability of suitable biological model systems. This study aimed to develop a disease-specific in vitro model for OCA type 1A, the most severe form caused by TYR (tyrosinase) gene mutations, using retinal pigment epithelium (RPE) differentiated from patient-derived human-induced pluripotent stem cells (hiPSCs). A comparative study between healthy and OCA1A RPE cells revealed that while healthy RPE cells exhibited timely onest of pigmentation during differentiation, OCA1A RPE cells failed to pigment even after an extended culture period. This observation was validated by ultrastructural studies using electron microscopy, hinting at melanosome-specific defects. Immunocytochemistry demonstrated abnormal expression patterns of melanogenesis-specific protein markers in OCA1A RPE cells, indicating reduced or absence of melanin synthesis. Next, a quantitative assay was performed to confirm the absence of melanin production in OCA1A RPE cells. Tyrosinase assay showed no activity in OCA1A compared with healthy RPE, suggesting non-functionality of TYR, further corroborated by western blot analysis showing complete absence of the protein. Gene expression by RNA sequencing of healthy and OCA1A RPE cells uncovered differential gene expression associated with lens development, visual perception, transmembrane transporter activity, and key signaling pathways. This disease-in-a-dish model of OCA1A provides an excellent platform to understand disease mechanism, identify potential therapeutic targets, and facilitate gene therapy or gene correction.

Looking beyond the brain: Insights into vascular parkinsonism with optical coherence tomography.

BACKGROUND: Vascular Parkinsonism (VP) is characterized by rigidity and bradykinesia predominantly affecting the lower limbs. Optical Coherence tomography (OCT) facilitates the visualization of retina and choroid and may help in delineating differential involvement of retina and choroid in patients with VP. In this study, we report the pattern of changes in the retinal and choroidal layers in patients with VP with the help of spectral domain OCT (SD-OCT). METHODS: We adopted a case-control design and evaluated 24 patients with VP with complete history, clinical examination, Montreal Cognitive Assessment (MOCA), Unified Parkinson's Disease Rating Scale (UPDRS) motor part in OFF state, and retinal and choroidal imaging with SD-OCT. The peripapillary retinal nerve fiber layer (RNFL) thickness, peripapillary choroidal layer thickness (PPChT), central macular thickness (CMT) and subfoveal choroid thickness (SFChT) were assessed. Twenty-two age and gender-matched healthy control subjects were also recruited. RESULTS: The peripapillary RNFL, in most of the segments and CMT were significantly thinner in patients with VP compared to controls. The subfoveal and peripapillary ChT did not differ significantly between patients and controls. CONCLUSION: This is the first study that has evaluated the role of OCT in patients with VP and these patients have significant involvement of the retina. In addition to providing pathophysiological insights, OCT parameters may serve as disease biomarkers in VP. This study lays the foundation for carrying out future studies with larger sample sizes and a longitudinal design.

Clinical, imaging and genetic profile of twenty-four patients with pantothenate kinase-associated neurodegeneration (PKAN)- A single centre study from India.

INTRODUCTION: Pantothenate kinase-associated neurodegeneration (PKAN) is the most common "Neurodegeneration with Brain Iron Accumulation" disorder. This study aimed to study the clinical, radiological and genetic profiling of a large cohort of patients with PKAN. METHODS: This is an ambispective hospital-based single centre study conducted at a tertiary care centre from India. After tabulating the clinical details, appropriate rating scales were applied followed by magnetic resonance imaging brain and exome sequencing. The segregation of the causal variants in the families were analysed using Sanger sequencing. RESULTS: Twenty-four patients (14 males) with a median age at initial examination of 13 years (range: 4-54 years) and age at onset of 8 years (range: 0.5-40 years) were identified. Almost two-thirds (62%) had onset before 10 years. Difficulty walking was the most common presenting symptom (41.6%) and dystonia was the most common extrapyramidal phenomenology (100%) followed by parkinsonism (54.2%). Retinitis pigmentosa was present in 37.5% patients. MRI showed hypo intensity on T2 and SWI sequences in globus pallidus (100%), substantia nigra (70.8%) and red nucleus (12.5%). Eye-of-the-tiger sign was present in 95.8%. Biallelic variants in PANK2 gene was identified in all 20 patients who underwent genetic testing. Among the 18 unique variants identified in these 20 patients 10 were novel. Sanger sequencing confirmed the segregation of the mutation in the available family members. CONCLUSIONS: Wide range of age at onset was noted. Dystonia at presentation, pathognomonic eye-of-tiger sign, and disease-causing variants in PANK2 gene were identified in nearly all patients. Ten novel variants were identified expanding the genotypic spectrum of PKAN.

A systematic review and meta-analysis of optical coherence tomography studies in schizophrenia, bipolar disorder and major depressive disorder.

OBJECTIVES: Due to the common neurodevelopmental origin and easy accessibility, the retina serves as a surrogate marker for changes in the brain. Hence, Optical Coherence Tomography (OCT), a tool to examine the neuronal layers of retina has gained importance in investigating psychiatric disorders. Several studies in the last decade have reported retinal structural alterations in schizophrenia (SCZ), bipolar disorder (BD), and major depressive disorder (MDD). However, the findings are inconsistent. Hence, we conducted a meta-analysis to investigate alterations in OCT parameters in patients with SCZ, BD and MDD. METHODS: We searched electronic databases for studies that examined OCT parameters in patients with SCZ, BD and MDD published up to January 2023. The primary outcome measures were thickness and volumes of the retinal Nerve Fibre Layer (RNFL). We conducted meta-analysis using a random effects model. RESULTS: The searches yielded 2638 publications of which 43 studies were included in the final analysis across all disorders. Compared to controls, the RNFL was thinner in SCZ patients (SMD = -0.37, p = <0.001) and BD patients (SMD = -0.67, p = < 0.001), but not in MDD patients (SMD = -0.08, p = 0.54). On quadrant wise analysis, temporal quadrant RNFL was thinner in SCZ but not in BD, while all other quadrants were thinner in both SCZ and BD. CONCLUSION: We found significant reductions in RNFL thickness in SCZ and BD, but not in MDD. The differential involvement in various quadrants and parameters across the disorders has potential implications for using retinal parameters as a diagnostic biomarker.

Newer therapeutic options for inherited retinal diseases: Gene and cell replacement therapy.

Inherited retinal diseases (IRD) are genotypically and phenotypically varied disorders that lead to progressive degeneration of the outer retina and the retinal pigment epithelium (RPE) eventually resulting in severe vision loss. Recent research and developments in gene therapy and cell therapy have shown therapeutic promise in these hitherto incurable diseases. In gene therapy, copies of a healthy gene are introduced into the host cells via a viral vector. Clinical trials for several genes are underway while treatment for RPE65 called voretigene neparvovec, is already approved and commercially available. Cell therapy involves the introduction of stem cells that can replace degenerated cells. These therapies are delivered to the target tissues, namely the photoreceptors (PR) and RPE via subretinal, intravitreal, or suprachoroidal delivery systems. Although there are several limitations to these therapies, they are expected to slow the disease progression and restore some visual functions. Further advances such as gene editing technologies are likely to result in more precise and personalized treatments. Currently, several IRDs such as retinitis pigmentosa, Stargardt disease, Leber congenital amaurosis, choroideremia, achromatopsia, and Usher syndrome are being evaluated for possible gene therapy or cell therapy. It is important to encourage patients to undergo gene testing and maintain a nationwide registry of IRDs. This article provides an overview of the basics of these therapies and their current status.

Retinal Changes in Parkinson's Disease: A Longitudinal Follow-up Study.

Background: There is definite evidence for the involvement of retina in Parkinson's disease (PD). However, a specific pattern has not been clear due to the cross-sectional nature of the majority of the previous studies. Objective: The aim of this work was to study the pattern of changes in the retinal layers in patients with PD on longitudinal follow-up. Materials and Methods: Twelve patients with PD (23 eyes) were evaluated at baseline with complete history, clinical examination, Unified Parkinson's Disease Rating Scale (UPDRS) motor part, visual acuity, and retinal imaging with spectral-domain Optical Coherence Tomography. After a mean duration of 3.7 ± 0.46 years, patients were re-evaluated. Results: The Central Macular Thickness (CMT) of the right eye was found to be significantly thicker during the follow-up (P = 0.002). The outer retinal layer in the temporal quadrant at 0.5 centimeters from the fovea of the left eye was found to be significantly thinner (P = 0.001). Conclusion: The serial evaluation of the retinal layers in patients with PD suggests a progressive loss of thickness of the outer retinal layer. The involvement of non-dopaminergic mechanisms, especially glutamatergic pathways, may be responsible for these changes.

Derivation of three induced pluripotent stem cell lines under feeder-free culture conditions from peripheral blood mononuclear cells (PBMC) of Indian patients suffering from inherited retinal diseases carrying different mutations.

Inherited retinal diseases (IRDs) are clinically and genetically heterogenous diseases affecting the neural retina and retinal pigment epithelium resulting in irreversible blindness. Owing to advantages like ease of access for treatment, one eye being a perfect natural control for the other, and immune privileged environment, research exploring treatment for these retinal diseases has advanced remarkably. We describe the generation of induced pluripotent stem cell (iPSC) lines from peripheral blood mononuclear cells (PBMC) of three patients with IRDs. These well-characterized iPSC lines provide an ideal platform to investigate normal and pathological retinogenesis for drug screening and personalized cell therapy.

Induced pluripotent stem cells (iPSC)-derived retinal cells in disease modeling and regenerative medicine.

Retinal degenerative disorders are a leading cause of the inherited, irreversible and incurable vision loss. While various rodent model systems have provided crucial information in this direction, lack of disease-relevant tissue availability and species-specific differences have proven to be a major roadblock. Human induced pluripotent stem cells (iPSC) have opened up a whole new avenue of possibilities not just in understanding the disease mechanism but also potential therapeutic approaches towards a cure. In this review, we have summarized recent advances in the methods of deriving retinal cell types from iPSCs which can serve as a renewable source of disease-relevant cell population for basic as well as translational studies. We also provide an overview of the ongoing efforts towards developing a suitable in vitro model for modeling retinal degenerative diseases. This basic understanding in turn has contributed to advances in translational goals such as drug screening and cell-replacement therapies. Furthermore we discuss gene editing approaches for autologous repair of genetic disorders and allogeneic transplantation of stem cell-based retinal derivatives for degenerative disorders with an ultimate goal to restore vision. It is pertinent to note however, that these exciting new developments throw up several challenges that need to be overcome before their full clinical potential can be realized.

Next generation sequencing identifies novel disease-associated BEST1 mutations in Bestrophinopathy patients.

Bestinopathies are a spectrum of retinal disorders associated with mutations in BEST1 including autosomal recessive bestrophinopathy (ARB) and autosomal dominant Best vitelliform macular dystrophy (BVMD). We applied whole-exome sequencing on four unrelated Indian families comprising eight affected and twelve unaffected individuals. We identified five mutations in BEST1, including p.Tyr131Cys in family A, p.Arg150Pro in family B, p.Arg47His and p.Val216Ile in family C and p.Thr91Ile in family D. Among these, p.Tyr131Cys, p.Arg150Pro and p.Val216Ile have not been previously reported. Further, the inheritance pattern of BEST1 mutations in the families confirmed the diagnosis of ARB in probands in families A, B and C, while the inheritance of heterozygous BEST1 mutation in family D (p.Thr91Ile) was suggestive of BVMD. Interestingly, the ARB families A and B carry homozygous mutations while family C was a compound heterozygote with a mutation in an alternate BEST1 transcript isoform, highlighting a role for alternate BEST1 transcripts in bestrophinopathy. In the BVMD family D, the heterozygous BEST1 mutation found in the proband was also found in the asymptomatic parent, suggesting an incomplete penetrance and/or the presence of additional genetic modifiers. Our report expands the list of pathogenic BEST1 genotypes and the associated clinical diagnosis.

Genetic analysis and clinical phenotype of two Indian families with X-linked choroideremia.

PURPOSE: This study aims to describe the phenotype and genotype of two Indian families affected with X-linked choroideremia (CHM). MATERIALS AND METHODS: In these two families, the affected individuals and unaffected family members underwent a comprehensive ophthalmic examination including an optical coherence tomography (OCT) and electroretinogram. Blood samples were collected from the families for genetic analysis. Next generation sequencing (NGS) was done using a panel of 184 genes, which covered previously associated genes with retinal dystrophies. Sequencing data were analyzed for the CHM, RPGR, and RP2 genes that have been implicated in CHM and X-linked retinitis pigmentosa (XLRP), respectively. The identified variants were confirmed by Sanger sequencing in available individuals and unrelated controls. RESULTS: In two unrelated male patients, NGS analysis revealed a previously reported 3'-splice site change c.820-1G>C in the CHM gene in the first family and hemizygous mutation c.653G>C (p.Ser218X) in the second family. The asymptomatic family members were carriers for these mutations. Spectral domain-OCT showed loss of outer retina, preservation of the inner retina, and choroidal thinning in the affected males and retinal pigment epithelial changes in the asymptomatic carriers. The identified mutations were not present in 100 controls of Indian origin. There were no potential mutations found in XLRP-associated (RPGR and RP2) genes. CONCLUSION: This report describes the genotype and phenotype findings in patients with CHM from India. The identified genetic mutation leads to lack of Rab escort protein-1 (REP-1) or affects the production of a REP-1 protein that is likely to cause retinal abnormalities in patients.

Melanoma associated retinopathy: A new dimension using adaptive optics.

We report a 56-year-old male patient, complaining of metamorphopsia in his left eye nevertheless visual acuity, slit lamp, and fundus examinations were within normal limits. Microperimetry (MAIA, Centervue, Italy) revealed central field loss and spectral domain optical coherence tomography (Spectralis, Heidelberg, Germany) showed disrupted cone outer segment tip layer. The patient had a diagnosis of cutaneous melanoma in his foot for which an excision biopsy with lymph node dissection was performed 5 months earlier. Our clinical diagnosis was melanoma-associated retinopathy. Electrophysiology confirmed the diagnosis. Adaptive optics retinal imaging (Imagine eyes, Orsay) was performed to assess the cone mosaic integrity across the central retina. This is the first report on the investigation of autoimmune retinopathy using adaptive optics ophthalmoscopy. This case highlights the viability of innovative diagnostic modalities that aid early detection and subsequent management of vision threatening retinal.

Optical coherence tomography as a tool to evaluate retinal changes in Parkinson's disease.

BACKGROUND: Though Parkinson's disease (PD) is primarily a disease of the basal ganglia, recent evidence suggests that PD affects the retina. OBJECTIVE: The study was designed to evaluate the thickness of retinal nerve fiber layer (RNFL) and thickness and volume of the macula in PD and hence explore the utility of optical coherence tomography (OCT) in studying retinal changes in PD. METHODS: A prospective, hospital based evaluation of 30 patients with PD and 30 healthy controls was carried out. Various parameters such as RNFL, central macular thickness (CMT), central and total macular volumes (TMV) and retinal thickness were analyzed using OCT. RESULTS: (a) RNFL thickness was not significantly different between the patients and controls. A significant negative correlation was found between the RNFL thickness in the right nasal superior sector and the UPDRS motor score. (b) CMT was found to be significantly reduced in the right eye and a negative correlation with the UPDRS motor score was noted. (c) TMV was significantly greater in patients compared to the controls. (d) The outer retinal layer in the right nasal quadrant and the right inferior quadrants were found to be significantly thinner in patients with PD. CONCLUSIONS: We did not find any significant abnormality in the RNFL thickness in patients with PD. Decreased CMT in patients with PD and a significant negative correlation of RNFL thickness and CMT with severity of PD suggest a remote possibility of dopaminergic depletion in the retina. However long term studies are warranted to validate our findings.

Retinal oxygen saturation in retinitis pigmentosa and macular dystrophies in asian-Indian eyes.

PURPOSE: To study the oxygen-saturation profiles in RP and macular dystrophies and compare them with age-matched healthy controls. METHODS: In a cross-sectional prospective study, 62 subjects with RP, 23 with macular dystrophies, and 78 controls were enrolled, and retinal oximetry was performed with the Oxymap T1 retinal oximeter. The images were analyzed for oxygen saturation and diameter of retinal vessels. RESULTS: All parameters showed a significant difference among the three groups. Patients with RP showed significantly lower diameters (98.4 µm and 136.9 µm arteriolar and venous) (P < 0.001), higher saturations (102.3% and 59.1%) (P < 0.001; 0.06), and higher arterio-venous saturation difference (AVSD) (43%) (P < 0.001) compared with the other two groups. Macular dystrophies showed higher global arteriolar values (96.7%) and AVSD (41.6%) but comparable venous values (54.9%) to the control group (90.6%, 57.4%, and 33.3%). CONCLUSIONS: Oximetry is sensitive in quantifying hemodynamic changes in retinal dystrophies. It is still unclear whether these hemodynamic changes are a cause or a result of the disease process.

Identification of Novel Mutations in ABCA4 Gene: Clinical and Genetic Analysis of Indian Patients with Stargardt Disease.

Stargardt disease (STGD) is the leading cause of juvenile macular degeneration associated with progressive central vision loss, photophobia, and colour vision abnormalities. In this study, we have described the clinical and genetic features of Stargardt patients from an Indian cohort. The next generation sequencing was carried out in five clinically confirmed unrelated patients and their family members using a gene panel comprising 184 retinal specific genes. Sequencing results were analyzed by read mapping and variant calling in genes of interest, followed by their verification and interpretation. Genetic analysis revealed ABCA4 mutations in all of the five unrelated patients. Among these, four patients were found with compound heterozygous mutations and another one had homozygous mutation. All the affected individuals showed signs and symptoms consistent with the disease phenotype. We report two novel ABCA4 mutations in Indian patients with STGD disease, which expands the existing spectrum of disease-causing variants and the understanding of phenotypic and genotypic correlations. Screening for causative mutations in patients with STGD using panel of targeted gene sequencing by NGS would be a cost effective tool, might be helpful in confirming the precise diagnosis, and contributes towards the genetic counselling of asymptomatic carriers and isolated patients.

Exome sequencing is an efficient tool for variant late-infantile neuronal ceroid lipofuscinosis molecular diagnosis.

The neuronal ceroid-lipofuscinoses (NCL) is a group of neurodegenerative disorders characterized by epilepsy, visual failure, progressive mental and motor deterioration, myoclonus, dementia and reduced life expectancy. Classically, NCL-affected individuals have been classified into six categories, which have been mainly defined regarding the clinical onset of symptoms. However, some patients cannot be easily included in a specific group because of significant variation in the age of onset and disease progression. Molecular genetics has emerged in recent years as a useful tool for enhancing NCL subtype classification. Fourteen NCL genetic forms (CLN1 to CLN14) have been described to date. The variant late-infantile form of the disease has been linked to CLN5, CLN6, CLN7 (MFSD8) and CLN8 mutations. Despite advances in the diagnosis of neurodegenerative disorders mutations in these genes may cause similar phenotypes, which rends difficult accurate candidate gene selection for direct sequencing. Three siblings who were affected by variant late-infantile NCL are reported in the present study. We used whole-exome sequencing, direct sequencing and in silico approaches to identify the molecular basis of the disease. We identified the novel c.1219T>C (p.Trp407Arg) and c.1361T>C (p.Met454Thr) MFSD8 pathogenic mutations. Our results highlighted next generation sequencing as a novel and powerful methodological approach for the rapid determination of the molecular diagnosis of NCL. They also provide information regarding the phenotypic and molecular spectrum of CLN7 disease.

Perioperative optic neuropathy in patients undergoing off-pump coronary artery bypass graft surgery.

AIMS AND OBJECTIVES: Perioperative optic neuropathy (PON) is a rare, but devastating complication following coronary artery bypass graft surgery (CABG). We performed a retrospective study of PON associated with off-pump CABG (OPCABG) to identify possible risk factors. MATERIALS AND METHODS: 1442 patients underwent OPCABG over a 10-month period from October 2008 to August 2009; PON was identified in four (0.28%) patients. A retrospective review of the charts was done to identify the patient characteristics, pre-operative status, intra-operative details, and ophthalmic examination details. Friedman test was used to compare the hematocrit (Hct) and the mean arterial pressure (MAP) values across the three time periods: Pre-, intra- and post-operative periods. RESULTS: All four patients were male, diabetic, and in the age range 51-69 years. All patients noted unilateral or bilateral severe visual loss in the immediate post-operative period, which was permanent. All the four patients had statistically significant decrease in the Hct (P < 0.039) and mean arterial blood pressure (P < 0.018) in the intraoperative and post-operative period when compared to pre-operative value. CONCLUSIONS: PON is a rare but definite possibility in patients undergoing OPCABG. Diabetes mellitus may be a risk factor. Perioperative hemodynamic abnormalities like decrease in MAP and anemia may play a role in the development of PON in OPCABG.