Changes in retinal nerve fiber layer thickness may be the cause of post-COVID-19 headaches.

OBJECTIVE: The prevalence of post-COVID headaches is not low. The eye can be affected by this infection, but it is not clear yet what the relationship is between persistent headaches and the thickness of the retinal nerve fiber layer (RNFL) after COVID-19 infection this study aims to investigate the relationship between these subjects. METHODS: In this retrospective study, in patients who have had a persistent headache, SD-OCT analysis of RNFL was obtained, and RNLF thickness values before and after COVID-19 infection were analyzed. RESULTS: A total of 26 eyes from 13 patients (nine (69.2%) females, four (30.8%) males) with persistent headaches after COVID-19 infection were studied. The average age was 47,35 years for females and 63 years for males. The mean RNFL thickness of both eyes between before and after COVID-19 infection decreased, which was statistically significant. CONCLUSION: In this study, a correlation between headache and changes in RNLF after COVID-19 infection was found. It may have wider ramifications to look into the COVID-19-associated headache phenotype of people with a history of migraines, contributing to a more comprehensive understanding of migraine pathogenesis. This relationship can provide further insight into this infection.

New Evidence for Regulatory Role of Trigeminal Ganglion on the Intraocular Pressure Following Subarachnoid Hemorrhage.

BACKGROUND: Increased intraocular pressure (IOP) likely secondary to an activated oculo-trigeminal reflex network is an important issue following subarachnoid hemorrhage (SAH). The relationship between the IOP and trigeminal ganglion (TGG) following experimental SAH was investigated in this study. METHODS: Twenty-three rabbits were used in this study. Five rabbits (n = 5) were used as the control group, another 5 as the sham group (n = 5), and the remaining 13 (n = 13) as the study group. The study group was further divided into two groups of animals with mild (n = 6) and severe (n = 7) TGG degeneration. The IOP values were recorded. After 2 weeks, the animals were decapitated. The mean degenerated neuron density of TGGs was estimated by stereological methods and analyzed statistically. RESULTS: The average IOP values were 11.85, 14.12, and 21.45 mm Hg in the control (n = 5), sham (n = 5), and study (n = 13) groups, respectively. The mean degenerated neuron density was 34, 237, and 3,165 mm3 in the control, sham, and study groups, respectively. CONCLUSION: According to the findings of this study, the experimental SAH leads to changes in IOP by affecting the TGG. By predicting and preventing IOP elevation in the setting of SAH, our findings will shed light on secondary sequelae such as glaucoma and irreversible blindness.

Overlooked evidence for transmission deficit of pupillary light reflex can be secondary to trigeminal nerve ganglion degeneration following subarachnoid hemorrhage; preliminary experimental study.

OBJECTIVE: Although the effect of oculomotor and cervical sympathetic networks on pupil diameter is well known; the effect of the trigeminal nerve on pupil diameter has not been investigated yet. This subject was investigated. MATERIALS AND METHODS: Five of 23 rabbits were used as a control group (GI; n = 5); 0.5 ccs saline solution into cisterna magna injected animals used as SHAM (GII; n = 5); autologous blood injected to produce SAH used as the study group (GIII; n = 13) and followed up three weeks. Light-stimulated pupil diameters were measured with an ocular tomography device before, middle, and at the end of the experiment. Considering the sclera area/pupil area ratio index (PRI) as the pupillary reaction area, we used this equation for the pupil's rush to light. Degenerated neuron densities of trigeminal ganglia and pupil diameters compared with the Mann-Whitney U test. RESULTS: The PRI, degenerated neuron density of trigeminal ganglia (n/mm3) were: (2.034 ± 0.301)/(13 ± 3) in GI; (1.678 ± 0.211)/(46 ± 9) in GII; and (0.941 ± 0.136)/(112 ± 21) in GIII. P-values between groups as: p < 0.005 in GI/GII; p < 0.0001 in GII/GIII and p < 0.00001 in GI/GIII. CONCLUSION: Light stimulates the cornea which is innervated by the trigeminal nerves. This experimental study indicates that the pupil remains mydriatic as the cornea is damaged by trigeminal ischemia following SAH and blocks the light flow.

Protective Effect of Vaccinium myrtillus Extract on X-ray Irradiation-Induced Retinal Toxicity via eNOS and 8-OHdGexpression.

Every year, hundreds of thousands of cancer patients receive radiotherapy treatment. Oxidative stress is observed in healthy tissues due to irradiation exposure. The present study is the first to address the effects of Vaccinium myrtillus (whortleberry, WB) against the effects of x-ray irradiation on retinal tissue. Twenty-four Sprague-Dawley rats were randomly allocated into 4 groups: (1) control group: rats without any treatment, (2) x-ray irradiation group: 8 Gray (Gy) RT for 2 days, (3) 100 mg WB extract + x-ray irradiation group: 8 Gy irradiation for 2 days and followed by intraperitoneal (IP) WB extract (100 mg/kg) supplementation for 10 days, (4) 200 mg WB extract + x-ray irradiation group: 8 Gy irradiation for 2 days and followed by intraperitoneal (IP) WB extract (200 mg/kg) supplementation for 10 days. Eyes were enucleated on the 10th day after RT for histopathological, immunohistochemical (8-hydroxy deoxyguanosine (8-OHdG), endothelial nitric oxide synthase (eNOS), and biochemical analyses (glutathione peroxidase (GSH), and malondialdehyde (MDA). The GSH levels significantly decreased and MDA levels and 8-OHdG staining increased after x-ray irradiation compared to the control group. Combined x-ray irradiation +WB treatment significantly increased GSH levels and significantly decreased MDA production and 8-OHdG staining. However, eNOS staining was not affected in any of the groups. Besides, x-ray irradiation significantly increased cell losses and edematous areas. The WB significantly reversed the cellular damage in ganglion cells, inner nuclear, and outer nuclear layers in quantitative analyses. The x-ray irradiation caused significant retinal impairment, and additional WB therapy provided protective effects against radiation-induced retinopathy. These results may suggest WB extract as an adjuvant therapy to reverse retinal impairments after x-ray irradiation.

Interesting negative correlation between transorbital optic nerve sheath diameter and Evans' index values; can it be predictive for failure of endoscopic third ventriculostomy?

Background: Currently, Endoscopic third ventriculostomy (ETV) is one of the commonly used surgical options for the treatment of non-communicating hydrocephalus but reported success rates from ETV vary considerably, and a reliable noninvasive means to detect the efficacy of ETV is still lacking. In this study, the changes in Evans's Index and the transorbital optic nerve sheath (ONSD) diameter measurement after endoscopic third ventriculostomy were compared. Methods: Preoperative and early postoperative ultrasonographic ONSD measurement and preoperative and postoperative 3 months Evans' index of patients with hydrocephalus on whom ETVs were performed between 1 February 2018 and 23 May 2022 and analyzed. Results: The chart of 8 male and 2 female patients was analyzed. Their median age at presentation was 5.3 years (range 1 - 14 years). Mean ONSD values were 5.66 mms in the preoperative period, which was decreased to a mean of 4.17 mms in the early postoperative period. The Evans' index was 0.5320 in the preoperative period; however, it decreased to 0.4460 in the postoperative 3rd months. The preoperative and early postoperative mean ONSD values and Evans' Index of patients were significantly different. Interestingly, a negative correlation was also observed between ONSD values and Evans' index. Conclusions: ONSD measurement and Evans' index have been commonly used after ETV procedures In pediatric patients with hydrocephalus. Still, there is an unexplained negative correlation between ONSD and Evans' index values. This study indicates that the two measures (Evans's index and ONSD) should be considered when performing follow-up examinations in patients after ETV.

Evaluation of tear parameters and meibomian gland morphology in keratoconus patients after epithelial-on corneal cross-linking.

PURPOSE: To evaluate the variations in tear parameters and meibomian gland morphology after epithelial-on (epi-on) corneal collagen cross-linking (CXL) in keratoconus (KC) patients. METHODS: This prospective observational study included 38 KC eyes that underwent epithelium-on CXL. Thirty-three eyes of 33 stable KC patients with no prior CXL treatment formed the KC group and 35 eyes of 35 healthy volunteers were recruited as the control group. All participants were evaluated by Schirmer I test, first and average noninvasive tear break-up time (NITBUT), ocular surface disease index (OSDI) questionnaire, and meibography scores. The CXL patients were evaluated preoperatively and at the 1st, 3rd, and 6th months, and participants without any intervention (KC and control groups) were evaluated initially, at 1st, 3rd, and 6th months. RESULTS: The KC patients had significantly lower average NITBUT, higher OSDI scores, and impaired meibomian gland morphology than healthy individuals (NITBUT(seconds): KC, 12.8(2.4-17.6), healthy group (HG), 17.1(6.8-17.6); p = 0.012, OSDI: KC, 27.5(0.0-87.5), HG, 7.5(0.0-55.0); p < 0.001, p < 0.001, respectively). A significant difference was found in Schirmer values of the CXL group at 0-1st months, first NITBUT values at 1-6 months, and average NITBUT values at 1-3 and 1-6 months (p = 0.003, p = 0.001, p = 0.003, p = 0.001, respectively). All meibography parameters remained unchanged after CXL over a 6-month follow-up compared to initial measurements. CONCLUSIONS: Even though the KC patients had lower NITBUT, higher OSDI scores, and increased meibomian gland disfunction, the CXL treatment did not significantly affect tear quantity, dry eye symptoms, and meibomian gland morphology.

Increased serum concentration of netrin-1 after intravitreal bevacizumab injection: is it a compensatory mechanism to counteract drug side effects?

BACKGROUND: To evaluate alterations in the serum concentrations of vascular endothelial growth factor (VEGF) and netrin-1 after intravitreal bevacizumab (BCZ) injection for the treatment of diabetic macular edema (DME). METHODS: This prospective case-control study included a total of 50 participants assigned to one of three groups, including 10 individuals with DME and non-proliferative diabetic retinopathy (NPDR), 13 with DME, and proliferative diabetic retinopathy (PDR), and 27 healthy individuals as a control group. Serum VEGF and netrin-1 concentrations were measured by enzyme-linked immunosorbent assays (ELISAs) immediately before, as well as 1 week and 1 month after, intravitreal BCZ injection. RESULTS: The mean VEGF serum concentrations in the PDR and NPDR groups were 388.4 and 196.9 pg/mL at baseline, respectively. After 1 week, these concentrations changed to 193.41 and 150.23 pg/mL, respectively (P = 0.001 and P = 0.005, respectively); after 1 month, the concentrations were 97.89 and 76.46 pg/mL, respectively (P = 0.001 and P = 0.009, respectively). The mean netrin-1 serum concentrations in the PDR patients and NPDR groups were 318.2 and 252.7 pg/mL at baseline, respectively. After 1 week, these concentrations increased to 476.6 and 416.3 pg/mL, respectively (P = 0.033 and P = 0.005, respectively), and after 1 month, they were 676.6 and 747.5 pg/mL, respectively (P = 0.001 and P = 0.005, respectively). The correlation analysis revealed a significant inverse relationship between changes in serum VEGF and netrin-1 concentrations in both the PDR and NPDR groups (r = - 0.685, P = 0.029). CONCLUSIONS: Intravitreal BCZ injections work systemically to significantly decrease serum VEGF levels, leading to a significant upregulation in the concentration of another angiogenic mediator, netrin-1.

Serum 25-Hydroxy Vitamin D, Vitamin B12, and Folic Acid Levels in Progressive and Nonprogressive Keratoconus.

PURPOSE: To evaluate the serum 25-hydroxy vitamin D, vitamin B12, and folic acid (FA) levels in progressive and nonprogressive patients with keratoconus (KCN). METHODS: Fifty-five patients with KCN (28 progressive and 27 nonprogressive) who were followed up for at least 12 months were recruited and separated into 2 groups according to corneal topographic progression criteria. Age- and sex-matched 30 healthy individuals formed the control group. Serum vitamin D, B12, FA, and Ca levels were compared among control, nonprogressive, and progressive groups. The effect of gender, age, vitamin D, B12, and FA parameters on KCN progression was investigated. RESULTS: Serum vitamin D levels were 12.77 ± 5.52, 11.78 ± 4.32, and 17.40 ± 5.12 ng/mL in nonprogressive, progressive, and control groups, respectively. The serum vitamin D levels in KCN groups (nonprogressive and progressive) were significantly lower than the control group (P = 0.002 and P < 0.001, respectively). There was no significant difference between all groups in serum vitamin B12, FA, and Ca levels (P > 0.05). Decreased vitamin D levels significantly increased nonprogressive KCN probability 1.23 times and progressive KCN probability 1.29 times more than the control group (P = 0.002, 95% confidence interval, 0.708-0.925; P < 0.001, 95% confidence interval, 0.668-0.888, respectively). CONCLUSIONS: Serum vitamin D levels were significantly decreased in both KCN groups. However, serum vitamin B12, FA, and Ca levels were similar in all groups. Serum vitamin D evaluation of patients with KCN at onset and follow-up examinations may help to predict the course of the disease.

The impact of hybrid contact lenses on keratoconus progression after accelerated transepithelial corneal cross-linking.

PURPOSE: To investigate the effect of hybrid contact lenses (HCLs) on keratoconus (KCN) progression after accelerated transepithelial cross-linking (A-TE CXL). METHODS: Thirty-five eyes of 26 patients who preferred Ultrahealth HCLs for an optical correction after A-TE CXL formed the study group, and 45 eyes of 34 patients who preferred spectacle correction were age- and sex-matched to form the control group. Corrected distance visual acuity (CDVA), maximum keratometry, mean keratometry, apical posterior keratometry, cylindrical power, minimum corneal thickness, keratoconus vertex indices and curvature asymmetry indices obtained by Scheimpflug corneal topography were compared before, 6 and 12 months after the procedure. Anterior segment optic coherence tomography (AS-OCT) was performed to measure the apical corneal clearance of HCL-wearing patients. RESULTS: The median pre-CXL CDVA value of the patients in the HCL group was logMAR 0.30 (0.20-1.0), and it was logMAR 0.30 (0.10-1.0) in the spectacle-corrected group. There was a significant increase in CDVA 6 and 12 months after CXL procedure in both groups (p < 0.001, 0.003, respectively). The median front curve asymmetry index (FCAsym) significantly improved after A-TE CXL in the HCL group. The pre-CXL and 12th-month topographic comparisons of the spectacle-corrected group revealed no significant difference. In addition, no significant difference was observed between topographic alterations of two groups (p > 0.05). CONCLUSION: The CDVA significantly improved, and KCN progression was halted in patients wearing HCL 12 months after A-TE CXL. Besides, FCAsym indices can be considered for follow-up of the HCL-wearing patients as an assistive parameter to AS-OCT measurements.

Is Netrin-1 Deficiency Responsible for Inflammation and Systemic Diseases Related to Pseudoexfoliation?

PRECIS: Serum netrin-1 levels are significantly lower in patients with pseudoexfoliation syndrome (PES) and pseudoexfoliative glaucoma (PEG) compared with the control group. PURPOSE: To investigate serum netrin-1 levels in PES and PEG patients and to determine the relevance of this molecule in the etiopathogenesis of PES-related and PEG-related diseases. MATERIALS AND METHODS: This prospective study included 29 PES and 17 PEG patients in the study groups and age-sex matched 47 cataract patients without pseudoexfoliative accumulation as a control group. Serum netrin-1 levels were measured by enzyme-linked immunosorbent assay. RESULTS: Serum netrin-1 level was significantly lower in the PES and PEG groups compared with the control group (P=0.007). Multinominal logistic regression analysis was performed in terms of netrin-1 levels ≤712.9 pg/mL, >712.9 pg/mL and sex which may affect PES and PEG. It were found that netrin-1 was a significant negative predictor for PES (odds ratio, 3.45; 95% confidence interval, 1.230-9.716; P=0.019) and PEG (odds ratio, 3.57; 95% confidence interval, 1.008-12.669; P=0.049), respectively. CONCLUSIONS: Decreased serum netrin-1 levels were detected in PES and PEG patients, similar to atherosclerosis and Alzheimer disease. Inflammation lays behind in the common pathogenesis of these diseases. Therefore, netrin-1 promises a potential anti-inflammatory role.

Pupillometry measurement and its relationship to retinal structural changes in children with attention deficit hyperactivity disorder.

PURPOSE: This study aims to assess the pupillometry measurements of the attention deficit hyperactivity disorder (ADHD) patients and to investigate their correlations with macular and RNFL thickness parameters by comparing the values with a healthy control group. METHODS: Newly diagnosed ADHD patients in a child and adolescent clinic of a tertiary hospital were consulted in an ophthalmology clinic. All participants had undergone a standard ophthalmological examination including refractometry, best corrected visual acuity, color vision, anterior segment biomicroscopy, fundoscopy, pupillometry, and OCT. All results were compared with a healthy control group at the same age. RESULTS: The study group consisted of 32 patients and there were 43 children in the control group. Mean pupillary velocities of ADHD patients and control group were 0.60 ± 0.11 mm/s and 0.63 ± 0.11 mm/s, and 0.49 ± 0.12 mm/s and 0.50 ± 0.10 mm/s, for right and left eyes, respectively. The difference was statistically significant for both eyes (p < 0.05). Mean RNFL thickness measurements of the study group were 90.69 ± 8.58 µm and 89.63 ± 8.14 µm for right and left eyes, respectively and those were 87.35 ± 7.67 µm and 88.77 ± 7.44 µm, respectively in the healthy group. Correlation between right pupillary velocity and RNFL thickness was statistically significant (r = 0.339, p = 0.003). CONCLUSION: Higher pupillary velocity values were observed in both eyes of children with ADHD and that was positively correlated with RNFL measurements of their right eyes.

What Are We Missing From Asymmetric Relationship Between the Retinal Nerve Fiber Layer Thickness Profiles and Sphenoid Sinus Volume?

PURPOSE/AIM OF THE STUDY: Detailed analysis of retinal structure such as the retinal nerve fiber layer can be performed by spectral-domain optical coherence tomography (OCT). There are no published studies concerning a relationship between retinal nerve fiber layer and human sphenoid sinus volumes. We investigated this relationship. MATERIAL AND METHODS: Spectral-domain OCT. The peripapillary retinal nerve fiber layer (RNFL) thickness and sphenoid sinus volume estimation of both sides of sex-matched patients were retrospectively analyzed. RESULTS: The mean RNFL thicknesses at the left side (91.8 µm) were significantly smaller than the right side (94.5 µm) (P = 0.040). However, the mean left sinus volume (44.5 cm) is larger than the right side, (34.5 mm) (P < 0.005). Left and right differences of both parameters are statistically significant (P < 0.05). CONCLUSION: There is a negative correlation between mean RNFL thicknesses and mean sinus volumes. To our knowledge, this article is the first report demonstrating the asymmetry relationship between RNFL and sphenoid sinus volumes.

Describing a New Mechanism of Retinal Detachment Secondary to Ophthalmic Artery Vasospasm Following Subarachnoid Hemorrhage: An Experimental Study.

BACKGROUND: The pterygopalatine ganglion (PPG) and ophthalmic arteries (OpAs) have important roles in ocular autoregulation and retinal and visual functions. The relationship between PPG neuron density, OpA vasospasm, and retinal detachment in subarachnoid hemorrhage (SAH) has never been studied. METHODS: This study was conducted on 25 rabbits. Five animals were in the control group (GI; n = 5), five in the sham group (GII; n = 5), and 15 in the study group (GIII; n = 15). After injection of 1 cc serum saline into the cisterna magna in the sham group, and autologous blood in the SAH group, the animals were followed for 3 weeks. All animals underwent a retinal examination five times a week for 3 weeks before and after the experiment. After the experiment, the neuron density of PPGs of the facial nerves, vasospasm index (VSI) of OpAs, and total basal surface values of the detached retinal parts (DRPs) were calculated. RESULTS: In the funduscopic examination, intravitreous hemorrhage ( Terson's syndrome) was detected in four animals in the SAH group. In the control groups, neuron density was 12,000 ± 1,240/mm3, VSI = 0.345 ± 0.076, and DRP = 0 to 1.5 mm2. Mean neuron density was 9,450 ± 940/mm3, VSI = 1.645 ± 0.940, and DRP = 6.23 ± 1.61 mm2 in the sham group (p < 0.05). Neuron density was 6,890 ± 932/mm3, VSI = 2.92 ± 0.97, and DRP = 9.43 ± 2.54 mm2 in SAH group. CONCLUSION: Mean neuron density, VSI of OpAs, and DRP values differed statistically significant between the SAH group and other groups (p < 0.005). There is an inverse relationship between PPG neurons and DRP. However, a direct relationship was observed between the mean VSI and DRP values.

Glaucoma With Alkaptonuria as a Result of Pigment Accumulation.

PURPOSE: To report a case of alkaptonuria (AKU) in a patient with bilateral conjunctival and scleral black colorization who was diagnosed with glaucoma thereafter. METHODS: This is a single case report. RESULTS: A 67-year-old male patient with bilateral black colorization of conjunctiva and sclera was referred to our hospital. In the biomicroscopic examination, globular dark pigmentation was observed in the conjunctiva, sclera, and limbal cornea. The patient was diagnosed with a nuclear cataract in both eyes. He also had gray skin pigmentation at his nose and paranasal area. Corneal topography examination revealed irregular astigmatism. Intraocular pressure values were 29 and 31 mm Hg, in the right and left eye, respectively, with Goldmann applanation tonometry. The diagnosis of AKU was made after pathologic assessment of conjunctival biopsy by the internal medicine department. CONCLUSIONS: AKU is characterized by the accumulation of homogentisic acid in the connective tissues of many organs including the eye. Patients should be carefully examined in ophthalmology clinics in order to not miss systemic diagnoses. It should be kept in mind that AKU may cause iridocorneal angle pigmentation, which leads to glaucoma, and patients should be treated with proper medication when presenting with elevated intraocular pressure values.

Direct and crossover effects of brinzolamide, betaxolol, and latanoprost on choroidal thickness.

PURPOSE: To investigate the acute effects of brinzolamide, betaxolol, and latanoprost (drugs commonly used in the medical management of glaucoma) on choroidal thickness using enhanced depth imaging optical coherence tomography (EDI-OCT). METHODS: Ninety healthy volunteers were evaluated in this prospective study. Participants were randomly divided into 3 groups. Brinzolamide, betaxolol, and latanoprost were administered into the left eyes of the first group (n = 30), second group (n = 30), and third group (n = 30), respectively, and artificial tear (Sodium hyaluronate) was instilled into the right eyes of all participants. Subfoveal choroidal thickness (SFCT) was measured using EDI-OCT before and 45 minutes after administration of the antiglaucomatous drops. RESULTS: SFCT revealed a significant increase in the left eye (administered antiglaucomatous drop) in the brinzolamide (p = 0.001) and betaxolol groups (p = 0.049) and a significant increase also in the right eye (administered artificial drop) in the brinzolamide (p = 0.001) and betaxolol groups (p = 0.001). However, SFCT did not reveal a significant increase in the left eye (p = 0.213) or in the right eye (p = 0.062) in the latanoprost group. CONCLUSION: Brinzolamide and betaxolol caused an increase in SFCT, while latanoprost had no significant effect on SFCT.

The relation between retrobulbar blood flow and posterior ocular changes measured using spectral-domain optical coherence tomography in patients with obstructive sleep apnea syndrome.

PURPOSE: To 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. METHODS: The 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. RESULTS: Sixty 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. CONCLUSION: PI 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.

The protective effects of astaxanthin against cisplatin-induced retinal toxicity.

PURPOSE: This study investigated the toxic effects of an antineoplastic agent, cisplatin (CIS), on retinal cells and the potential capacity of astaxanthin (ASTA) to elicit a future therapeutic protocol in CIS-induced retinal toxicity. MATERIALS AND METHODS: Six groups were formed for the assessment; control (healthy; Group 1), olive oil (olive oil only; Group 2), ASTA control group (ASTA only, Group 3), the single intraperitoneal (IP) dose of 16 mg/kg CIS (CIS only group; Group 4), 16 mg/kg CIS +25 mg/kg (IP) ASTA (Group 5), and 16 mg/kg CIS +75 mg/kg (IP) ASTA (Group 6). On the third day after CIS administration, rats in all groups were sacrificed under anesthesia and the analysis of the biochemical parameters and histopathological levels were performed. RESULTS: A significant decrease in GSH levels and increases in MDA, eNOS, and 8-OHdG expressions were recorded. Additionally, CIS treatment had caused acidophilic staining in retinal histological appearance. ASTA treatment reduced the increases in MDA, eNOS, and 8-OHdG levels following CIS administration and increased the levels of GSH expressions, as well. CONCLUSIONS: These results may suggest that the ASTA molecule as a promising option to prevent retinal toxicity in patients receiving CIS treatment for malignant tumors.

The Protective Effect of Thiamine Pryophosphate Against Sugar-Induced Retinal Neovascularisation in Rats.

The aim of this study was to investigate the effect of thiamine pyrophosphate (TPP), administered via sugar water, on retinal neovascularisation in rats. Animals were assigned to three groups, namely the TPP sugar-water group (TPSWG, n = 12), the control group (CG, n = 12) and the healthy group (HG, n = 12). The TPSWG was injected intraperitoneally with TPP once a day for 6 months. CG and HG rats were given distilled water in the same way. TPSWG and CG rats were left free to access an additional 0.292 mmol /ml of sugar water for 6 months. The fasting blood glucose (FBG) levels of the animals were measured monthly. After 6 months, biochemical, gene expression and histopathologic analyses were carried out in the retinal tissues removed from the animals after they were killed. The measured FBG levels were 6.96 ± 0.09 mmol/ml (p < 0.0001 vs. HG), 6.95 ± 0.06 mmol/ml (p < 0.0001 vs. HG) and 3.94 ± 0.10 mmol/ml in the CG, TPSWG and HG groups, respectively. The malondialdehyde (MDA) levels were found to be 2.82 ± 0.23 (p < 0.0001 vs. HG), 1.40 ± 0.32 (p < 0.0001 vs. HG) and 1.66 ± 0.17 in the CG, TPSWG and HG, respectively. Interleukin 1 beta (IL-1ß) gene expression was increased (3.78 ± 0.29, p < 0.0001) and total glutathione (tGSH) was decreased (1.32 ± 0.25, p < 0.0001) in the retinal tissue of CG compared with TPSWG (1.92 ± 0.29 and 3.18 ± 0.46, respectively). Increased vascularisation and oedema were observed in the retinal tissue of CG, while the retinal tissues of TPSWG and HG rats had a normal histopathological appearance. A carbohydrate-rich diet may lead to pathological changes in the retina even in nondiabetics, but this may be overcome by TPP administration.

How Reliable Is Pupillary Evaluation Following Subarachnoid Hemorrhage? Effect of Oculomotor Nerve Degeneration Secondary to Posterior Communicating Artery Vasospasm: First Experimental Study.

BACKGROUND AND STUDY AIM: Basic neurophysiologic principles of the light reflex are well known. However, the effects of degenerated axon densities of oculomotor nerves (OMNs) secondary to posterior communicating artery (PComA) vasospasm following subarachnoid hemorrhage (SAH) have not been investigated. Our aim was to study this subject. METHODS: This study was conducted on 19 rabbits. There was a control group of five animals, a sham group of five animals in which saline was injected into the cisterna magna and a study group of nine animals in which homologous blood was injected into the cisterna magna. Pupillary diameters were measured for 1 week, then the animals were decapitated. The normal and degenerated axon densities of the OMNs were examined by stereological methods. Vasospasm indexes (VSIs) of posterior communicating arteries (PComAs) supplying OMNs were estimated and analyzed statistically. RESULTS: The pupillary diameter was 5.439 ± 368 µm, and the mean axon density of the OMNs was 0.924 ± 324/mm3 in the control group. The pupillary diameter and degenerated axon density of the OMNs in animals of the sham group were 6.980 ± 0.370 µm and 36 ± 8/mm3, respectively. The pupillary diameter was 9.942 ± 653 µm, and degenerated axon density of the OMNs was 265 ± 57/mm3 in animals with SAH. The mean VSI values of PComAs were 0.927 ± 0.224 in the control group, 1.542 ± 0.257 in the sham group, and 2.321 ± 0.324 in the SAH group. CONCLUSION: We found a linear relationship between the axon density of the OMNs and pupillary diameters. High degenerated neuron density in the OMNs may be responsible for an unresponsive pupillary that has not been mentioned in the literature.