Outcomes of three-piece rigid scleral fixated intraocular lens implantation in subjects with deficient posterior capsule following complications in manual small incision cataract surgery.

Objective: To evaluate the surgical visual outcomes of three-piece rigid scleral fixated intraocular lens (SFIOL) implantation in subjects with deficient posterior capsule following complications of cataract extraction. Design: Retrospective 4-year cohort study. Participants: Data from 174 eyes that underwent SFIOL combined with pars plana vitrectomy (PPV) between January 2018 and March 2022 and follow-up exams were included. Methods: Demographic characteristics including primary indications for surgery, history of trauma, laterality, baseline and best-corrected visual acuity (BCVA), refraction as spherical equivalent (SE), intraocular pressure (IOP), duration of follow-up, and complications were analyzed. Results: The mean preoperative BCVA was 1.38 ± 0.46 logarithm of the minimum angle of resolution (logMAR), which improved significantly to 0.37 ± 0.22 logMAR. The baseline refractive status measured in spherical equivalent (SE) was 4.1 ± 6.2 Diopters (D), and the postoperative status was -0.4 ± 0.97 D. Early postoperative complications included hypotony (n = 1; 0.57%, vitreous hemorrhage (n = 3; 1.72%), elevated IOP (n = 8; 4.59%), mild dilated pupil (n = 1; 0.57%) and corneal edema (n = 16; 9.19%). Late complications included in this study were retinal detachment (n = 1; 0.57%), cystoid macular edema (CME) (n = 1; 0.57%), primary glaucoma (n = 1; 0.57%), secondary glaucoma (n = 13; 7.47%), zonular dehiscence (n = 3; 1.72%), retinal pigment epithelium (RPE) changes (n = 3; 1.72%), choroidal coloboma (n = 2; 1.14%), posterior dislocation of posterior chamber IOL (PCIOL) (n = 1; 0.57%), corneal decompensation (n = 1; 0.57%), retinal hemorrhage (n = 1; 0.57%), macular hole (n = 1; 0.57%), chronic uveitis (n = 1; 0.57%), mild non-proliferative diabetic retinopathy (NPDR) (n = 3; 1.72%), and mild NPDR with diabetic macular edema (DME) (n = 1; 0.57%). Conclusion: Integrating IOL implantation with vitrectomy various posterior segment complications were resolved in the same setting without attempting a second surgery.

Inflammation and apoptosis, two key events induced by hyperglycemia mediated reactive nitrogen species in RGC-5 cells.

Nitrosative stress plays a critical role in retinal injury in high glucose (HG) environment of eye, but the mechanisms remain poorly understood. Here we tested the hypothesis that HG induced reactive nitrogen species (RNS) production acts as a key functional mediator of antioxidant depletion, mitochondrial dysfunction, biomolecule damage, inflammation and apoptosis. Our findings illustrated that exposure of cultured RGC-5 cells to HG significantly disrupts the antioxidant defense mechanism and mitochondrial machineries by increasing the loss of mitochondrial membrane potential (ΔÑ°M) and elevating mitochondrial mass. Furthermore, we used biochemical tools to analyze the changes in metabolites, sulfur amino acids (SAAs) such as L-glutathione (GSH) and L-cysteine (Cys), in the presence of HG environment. These metabolic changes were followed by an increase in glycolytic flux that is phosphofructokinase-2 (PFK-2) activity. Moreover, HG exposure results in a significant disruption of protein carbonylation (PC) and lipid peroxidation (LPO), downregulation of OGG1 and increase in 8-OHdG accumulations in RGC-5 cells. In addition, our results demonstrated that HG environment coinciding with increased expression of inflammatory mediators, cell cycle deregulation, decreased in cell viability and expression of FoxOs, increased lysosomal content leading to apoptosis. Pre-treatment of selective inhibitors of RNS significantly reduced the HG-induced cell cycle deregulation and apoptosis in RGC-5 cells. Collectively, these results illustrated that accumulated RNS exacerbates the antioxidant depletion, mitochondrial dysfunction, biomolecule damage, inflammation and apoptosis induced by HG exposure in RGC-5 cells. Treatment of pharmacological inhibitors attenuated the HG induced in retinal cells.

High glucose-induced ROS accumulation is a critical regulator of ERK1/2-Akt-tuberin-mTOR signalling in RGC-5 cells.

Hyperglycemia and oxidative stress are the primary stressors that elicit mitochondria specific cell stress in diabetes. Here we hypothesized that elevated level of ROS in high glucose (HG) environment, trigger mitochondrial stress by damaging mitochondrial DNA (mtDNA), altering inflammatory mediators, and neurodegenerative markers via stress signalling pathway in retinal ganglion cells (RGC-5). Mechanistically, our findings illustrated that the HG environment increases the ROS production in retinal cells leading to the disruption of antioxidant defence mechanism, and altering mitochondrial machinery such as an increase in loss of mitochondrial membrane potential (ΔΨm), increase in mitochondrial mass, and increase in mtDNA fragmentation. Furthermore, fragmented mtDNA escape from mitochondria into the cytosol, where it engaged with cyclic GMP-AMP synthase (cGAS) and stimulator of IFN gene (STING) phosphorylation and activate interferon regulatory factor 3 (IRF3) via ERK1/2-Akt-tuberin-mTOR dependent pathways. Our results further indicate that siRNA-mediated gene silencing of tuberin suppresses the strong downregulation of tuberin-mTOR-IRF3 activation. HG environment resulted in activation of IRF3, coinciding with the increased expression of inflammatory mediators and neurodegenerative markers. Pre-treatment of N-acetyl-l-cysteine (NAC) or ERK1/2 or phosphoinositide3-kinase (PI3-K)/Akt inhibitors in RGC-5 cells significantly reduced the HG-induced IRF3 expression and declined the expression of neurodegenerative markers. Collectively, our results demonstrates that HG-induced over production of ROS, disrupts the antioxidant defence mechanism and mitochondrial dysfunction, leading to alterations of inflammatory mediators and neurodegenerative markers through the ERK1/2-Akt-tuberin-mTOR dependent signalling pathway in RGC-5 cells.

Hyperglycemia-induced oxidative stress induces apoptosis by inhibiting PI3-kinase/Akt and ERK1/2 MAPK mediated signaling pathway causing downregulation of 8-oxoG-DNA glycosylase levels in glial cells.

Glial cells are very important for normal brain function and alterations in their activity due to hyperglycemia, could contribute to diabetes-related cognitive dysfunction. Oxidative insults often cause rapid changes in almost all cells including glial cells. However, pathophysiologic mechanisms that lead to diabetic complications are not completely elucidated. Therefore, we examined whether elevated glucose levels directly or indirectly disrupt antioxidant defense mechanisms causing alterations in signaling pathways, cell cycle dysregulation, and reactive oxygen/nitrogen species-mediated apoptosis in glial cells. Findings of this study demonstrated that exposure of glial cells to high glucose markedly induces cellular and molecular injuries, as evidenced by elevated levels of reactive oxygen/nitrogen species, biomolecules damage, cell cycle dysregulation, decrease in antioxidant enzymes, and decrease in cell viability. Pretreatment of cells with N-acetyl-L-cysteine reduced high glucose-induced cytotoxicity by increasing the levels of antioxidant enzymes, and decreasing the number of apoptotic cells. Further, at molecular level high glucose treatment resulted in a significant increase in phosphorylation of Akt, MAPKs, tuberin, down regulation of 8-oxoG-DNA glycosylase and increase in 8-hydroxydeoxyguanosine accumulations. Pretreatment of cells with N-acetyl-L-cysteine, phosphatidylinositol3-kinase/Akt and ERK1/2 inhibitors completely abolished the apoptotic effects of high glucose. Moreover, N-acetyl-L-cysteine significantly inhibited reactive oxygen/nitrogen species generation, elevated antioxidants levels, inhibited Akt, ERK1/2, tuberin phosphorylation, decreased 8-hydroxydeoxyguanosine accumulation and upregulated 8-oxoG-DNA glycosylase expression. Our results demonstrate that high glucose induces apoptosis and inhibits proliferation of glial cells, which may be mediated by the phosphorylation of tuberin, down regulation of 8-oxoG-DNA glycosylase and 8-hydroxydeoxyguanosine accumulation via activation of Akt and ERK1/2MAPK pathways.

Incidence of cystoid macular oedema in diabetic patients after phacoemulsification and free radical link to its pathogenesis.

PURPOSE: Postoperative onset of cystoid macular oedema (CME) in diabetic patients after cataract surgery is a frequent problem in working-age adults worldwide. Here, we investigate the postoperative development of CME in diabetic patients after undergoing phacoemulsification with other ailing factors associated with CME. METHODS: This prospective study included 65 Type 2 diabetic patients with no diabetic retinopathy (DR), mild to moderate DR, moderate to severe DR and proliferative DR who underwent phacoemulsification surgery. Indirect ophthalmoscopy, fluorescein angiograms and optical coherence tomography were taken for a period of 8 weeks postoperatively to determine visual outcome and development of CME. Serum samples were collected for the measurement of antioxidants and reactive oxygen species (ROS) levels. RESULTS: Our data showed that CME occurred postoperatively in 47% without pre-existing DR and 55% of eyes with pre-existing DR (p<005). Positive association was noticed between morbid conditions, like hypertension (p<0.01) and diabetic nephropathy (p<0.05), and postoperative incidence of CME. The activity of antioxidant enzymes in patients with DR was found to be lower as compared with diabetic (D) patients, but catalase activity was recorded the maximum in these patients. The ROS activity was recorded highest in the serum samples of DR becoming CME positive. CONCLUSIONS: The present results suggest that after phacoemulsification, the chance of development of CME in DR is more as compared to D. Moreover, the development of CME is significantly associated with decrease in antioxidant levels, increased ROS activities, hypertension, diabetic nephropathy, and hyperlipidaemia.

Central retinal artery occlusion and third cranial nerve palsy following nasal septoplasty.

BACKGROUND: Postoperative vision loss following routine nasal surgery is an extremely rare and devastating complication. We report a case of unilateral blindness due to central retinal artery occlusion associated with third cranial nerve following septoplasty. CASE REPORT: We report a patient who developed an unusual central retinal artery occlusion with unilateral blindness following nasal surgery under general anesthesia. A 45-year-old man underwent a nasal septal surgery for severe epistaxis. Soon after recovery, the patient noticed loss of vision in his right eye and was unable to lift his upper eyelid. Upon ophthalmic examinations, we determined that he had right-sided third cranial nerve palsy with central retinal artery obstruction and ptosis of right upper eyelid, restriction of ocular movements, and no perception of light in the right eye. Postoperative computerized tomography scan revealed multiple fractures of the left medial orbital wall, including one near the optic canal. Ptosis and ocular defects were recovered partially, but visual loss persisted until the last follow-up. CONCLUSION: This paper highlights one case of complete unilateral blindness from direct central retinal artery occlusion associated with third cranial nerve palsy following an apparently uneventful septorhinoplasty. Ophthalmologists and otolaryngologists should therefore be aware of the possible occurrence of such complications.