Volume measurement of the vitrectomised eye and its applications in practice.

PURPOSE: To estimate the vitreous cavity replacement volume after pars plana vitrectomy and analyze its correlation with axial length and refractive error. METHODS: Observational cross-sectional study on 103 eyes undergoing vitrectomy. Fluid-air exchange was performed using a soft-tip cannula connected to a PVC tubing, the distal end of which opened into a 10-cc syringe without the plunger. The collected fluid was measured (and correction factors applied) to estimate the vitreous cavity volume. RESULTS: The mean axial length of 103 eyes was 23.43 ± 1.54 mm. The mean vitreous cavity volume was 4.46 ± 0.83 mL (2.8-8.1 mL). There was a strong positive correlation between axial length and vitreous volume, which was stronger for pseudophakic and aphakic groups than for phakic groups. CONCLUSION: Accurate assessment of vitreous cavity volume can enable precise quantification of tamponade, intravitreal drugs, and intravitreal chemotherapeutic agents. This will allow better surgical outcomes, decreased toxicity, and increased cost-effectiveness due to lesser wastage. OBJECTIVE: To estimate the vitreous cavity replacement volume after pars plana vitrectomy and analyze its correlation with axial length and refractive error.

Evaluation of agreement in macular vascular density measured by different protocols: 4.5 mm × 4.5 mm and 6 mm × 6 mm.

PURPOSE: To evaluate the agreement in the macular vascular density (MVD) measured by two protocols: 4.5 mm × 4.5 mm and 6 mm × 6 mm. DESIGN: Cross-sectional observational study. METHODS: Healthy volunteers between the age group of 19 and 39 years were recruited. Topcon DRI OCT Triton plus (Topcon Corporation, Tokyo, Japan) was used to acquire the fovea-centered optical coherence tomography angiography (OCTA) image using two protocols: 4.5 mm × 4.5 mm and 6 mm × 6 mm. MVD was measured by the manufacturer software in the superficial capillary plexus slab in five regions: central, superior, nasal, inferior, and temporal subfields of early treatment diabetic retinopathy study grid in each protocol. RESULTS: The study included 79 eyes of 40 healthy volunteers. The difference in the mean MVD between two protocols was 3.84% in right eye and 4.2% in left eye in central subfield, 0.93% in right eye and 1.13% in left eye in superior subfield, 0.06% in right eye and 1.45% in left eye in nasal subfield, 1.65% in right eye and 0.7% in left eye in inferior subfield, 0.4% in right eye and 0.54% in left eye in temporal subfield. The measurements were significantly higher in 6 mm × 6 mm in central subfield in both the eyes and in nasal field in the left eye. Whereas, the measurements were significantly higher in 4.5 mm × 4.5 mm in superior and inferior subfield in both the eyes and in temporal subfield in the left eye. CONCLUSION: The protocols should not be used interchangeably and it is necessary to include recommendation of the field of view to measure MVD while standardizing OCTA reporting.

Targeted laser photocoagulation of larger capillary aneurysms with rim in diabetic macular edema.

This is a retrospective series of five eyes of four cases with diabetic macular edema (DME) secondary to large capillary aneurysms. Larger capillary aneurysms were identified noninvasively based on the presence of white rim in color photograph. On optical coherence tomography (OCT), the larger capillary aneurysms were seen as vertically oval structures with heterogeneous lumen and hyperreflective margin. Two of the four eyes were treated with intravitreal therapy with poor response before considering laser photocoagulation. In one eye, laser photocoagulation was considered as primary therapy in view of the poor response to intravitreal therapy in the fellow eye. In one eye, intravitreal steroid with prompt laser was considered. In one eye, laser was considered as primary therapy. Complete obliteration of the capillary lumen was noted on OCT in all the five eyes after laser photocoagulation. Complete resolution of macular edema was noted in all the five eyes with no recurrence over a follow-up period of 4-18 months. DME secondary to larger capillary aneurysms responds well to targeted laser photocoagulation. These larger capillary aneurysms can be identified on clinical examination and color photograph by the presence of white rim and can be confirmed on OCT.

Analysis of orbitofacial anthropometry in children with pseudostrabismus.

AIM: The aim of the study was to analyze orbitofacial anthropometric parameters such as inner and outer canthal distances (ICD and OCD), palpebral fissure length (PFL), interpupillary distance (IPD), and canthal index (CI) in children with pseudostrabismus and to compare the measured IPD (mIPD) with calculated IPD (cIPD). MATERIALS AND METHODS: This was a prospective study of sixty children (6 months-18 years) with pseudostrabismus. ICD, OCD, PFL, and IPD were measured by digital Vernier caliper. The formula used was cIPD: 0.21+0.24 ICD+0.58°CD for males and 1.4+0.31 ICD+0.41°CD for females. Values measured by caliper were compared with that calculated by the formula. The formula used was CI: ICD × 100/OCD. Data were analyzed statistically. RESULTS: The mean age was 6.66 ± 3.57 years. Telecanthus was the most common finding (55%). The mean ICD and OCD in males were 30.89 ± 3.33 mm and 87.96 ± 8.09 mm and in females were 30.91 ± 3.05 and 86.22 ± 6.81 mm, respectively. The mean right eye PFL in males was 28.53 ± 2.63 mm and in females was 27.66 ± 2.22 mm and left eye PFL in males was 28.53 mm ± 2.63 and in females was 27.66 ± 2.22 mm. CI in males was 35.10 ± 1.65 and in females was 35.84 ± 1.71. Mean mIPD and cIPD: male - 55.37 ± 4.75 mm and 58.56 ± 5.34 mm, female - 53.32 ± 4.74 mm and 46.26 ± 3.71 mm. A good agreement was found between mIPD and cIPD. CONCLUSION: This study helps in documenting the anthropometric pattern of the orbitofacial parameters in children with pseudostrabismus which can act as reference data. This helps in the management of orbitofacial, craniofacial syndromes/deformities and lid reconstructive surgeries in retaining ethnical features and obtaining better function. In children's spectacle frame 1 and lens making, where measuring IPD is difficult, cIPD can be a simple alternative.

Laser photocoagulation of a hypofluorescent perifoveal exudative vascular anomalous complex/capillary macroaneurysm.

PURPOSE: To report successful treatment of a hypofluorescent perifoveal exudative vascular anomalous complex (PEVAC)/capillary macroaneurysm. CASE DESCRIPTION: A 63 year old healthy gentleman had a perifoveal isolated aneurysmal lesion with white rim. Optical coherence tomography (OCT) showed cystoid macular edema (CME) with neurosensory detachment. The aneurysmal lesion was seen in the inner retina as a hyperreflective intraretinal structure with a heterogenous lumen suggestive of PEVAC/capillary macroaneurysm. OCT angiography showed a capillary loop and a slightly hyperreflective lesion at the tip of the loop in the superficial capillary plexus slab. Minimal reduction in edema was noted following one dose of intravitreal triamcinolone (2 mg). Fundus fluorescein angiography performed at 6 weeks demonstrated the capillary loop, but the aneurysmal lesion remained hypofluorescent with no definite leak in the late phase. Few perifoveal microaneurysms were seen in both the eyes. Six weeks later, focal laser photocoagulation of the aneurysmal lesion was performed, which resulted in complete resolution of macular edema at 1 month. There was no recurrence of macular edema till his recent follow up, which is 4 month post laser. DISCUSSION: PEVAC is typically described as unifocal lesion and is not associated with other retinal vascular abnormalities. But in this case, in addition to the lesion, perifoveal microaneurysms were seen in both the eyes. Despite the absence of leak on fundus fluorescein angiography, targeted focal laser photocoagulation resulted in complete resolution of macular edema at 1 month. CONCLUSION: Laser photocoagulation would be helpful even in hypofluorescent PEVAC/capillary macroaneurysms.

Presence and development of strabismus in children with telecanthus, epicanthus and hypertelorism.

Purpose: To study the presence and development of strabismus in children with telecanthus, epicanthus, and hypertelorism. Methods: This is a prospective, longitudinal, and observational study. Sixty children aged between 6 months and 18 years with telecanthus, epicanthus, and hypertelorism in isolation or in combination were recruited. A detailed analysis of the history, determination of best corrected visual acuity, complete evaluation of strabismus, and ocular examination were carried out. The presence of telecanthus, epicanthus, and hypertelorism and associated strabismus, if any, was noted. All children were followed up for a minimum and maximum period of 12 and 18 months, respectively, to analyze the strabismus (previously present) and for detection of strabismus in those who did not have. The data were analyzed descriptively with mean and standard deviation. Chi square test and Fishers exact test were used to analyze the data between the groups. A P value less than 0.05 was considered to be statistically significant. Results: Telecanthus was the most common lid feature (55%). At baseline, ten (16.66%) children had strabismus (six: esotropia; four: exotropia). Two (3.33%) children underwent surgery. One child developed exotropia at the third follow-up (18 months). At the end of the study, 11 (18.33%) children had strabismus. No significant association was seen between lid characteristics and the type of strabismus. Conclusion: Children with telecanthus, epicanthus, and hypertelorism in isolation or in combination may or may not have associated strabismus. These features can pose difficulty in strabismus diagnosis, which mandates a careful examination, especially in younger age groups and small-angle strabismus. On the other hand, children without strabismus need longer follow-up to detect the development of strabismus and to initiate further management at the earliest.

Predictors of visual outcome in post-fever retinitis: a retrospective analysis.

PURPOSE: To identify the predictors of final visual outcome in cases with post-fever retinitis (PFR). METHODS: This is a retrospective study of cases with diagnosis of post-fever retinitis. Colour fundus photograph and optical coherence tomography (OCT) parameters at presentation and final visit were analysed. Various factors at presentation [age, systemic illness, best-corrected visual acuity (BCVA), area of retinitis and hard exudates, OCT parameters], at final visit (OCT parameters) and the treatment modalities used were correlated with BCVA at final visit. RESULTS: Twenty-four eyes of 16 patients with PFR were included in the study. Median BCVA at presentation was 6/60 and at final visit was 6/9. By multiple linear regression after adjusting for other variables, for every 1 unit increase in height of subretinal fluid (SRF) at fovea at presentation, the value of final BCVA decreased by 0.001 unit. For every 1 unit increase in extent of ellipsoid zone (EZ) loss and subfoveal deposit height, the value of final BCVA decreased by 0.0001 unit and 0.004 unit, respectively. The baseline OCT parameters that had negative correlation with final BCVA included central macular thickness (r: - 0.5182, p: 0.02), maximum SRF height (r: - 0.5539, p < 0.01) and SRF height at fovea (r: - 0.582, p < 0.01). The OCT parameters at final visit which had a negative correlation with final BCVA included disorganisation of retinal inner layers (DRIL) within 1000 microns from centre of fovea (r: - 0.6494, p < 0.01), height of subfoveal deposit (r: - 0.7627, p < 0.01), horizontal extent of subfoveal deposit (r: - 0.6695, p < 0.01) and extent of EZ loss (r: - 0.8216, p < 0.01). CONCLUSION: Height of SRF at presentation, extent of EZ loss and subfoveal deposit height at final visit were associated with poor final BCVA in PFR.

Ocular Injury due to Arecanut: A Unique Occupational Hazard in Central Karnataka.

PURPOSE: To evaluate the ocular manifestations and visual outcomes of ocular injury by arecanut. METHODS: We analysed cases with ocular injury by arecanut from August 2018 to December 2019, retrospectively. Mode of injury, visual acuity and ocular manifestations of trauma were recorded. RESULTS: Out of the 40 cases, closed globe injuries were seen in 97.5% of cases. All the injuries were due to the direct impact of arecanut during harvesting. The mean age was 45.15 ± 12.84 years. The mean best-corrected visual acuity (BCVA) at presentation was 20/40. A significant number of cases (35%) required surgical intervention. Mean BCVA at final follow-up was 20/30 but 16.66% of cases had BCVA of <20/60 even after definitive therapy. CONCLUSION: Ocular trauma due to arecanut is an important and preventable cause of visual impairment in central Karnataka. Modifications in harvesting technique would prevent ocular injuries.

Formation of an oxo-radical of peroxovanadate during reduction of diperoxovanadate with vanadyl sulfate or ferrous sulfate.

Formation of oxygen radicals during reduction of H(2)O(2) or diperoxovanadate with vanadyl sulfate or ferrous sulfate was indicated by the 1:2:2:1 electron spin resonance (ESR) signals of the DMPO adduct typical of standard ()OH radical. Signals derived from diperoxovanadate remained unchanged in the presence of ethanol in contrast to those from H(2)O(2). This gave the clue that they represent a different radical, possibly (*)OV(O(2))(2+), formed on breaking a peroxo-bridge of diperoxovanadate complex. The above reaction mixtures evolved dioxygen or, when NADH was present, oxidized it rapidly which was accompanied by consumption of dioxygen. Operation of a cycle of peroxovanadates including this new radical is suggested to explain these redox activities both with vanadyl and ferrous sulfates. It can be triggered by ferrous ions released from cellular stores in the presence of catalytic amounts of peroxovanadates.

Diperoxovanadate participates in peroxidation reactions of H2O2 in presence of abundant catalase.

Vanadate forms a stable complex with H2O2 at pH 7.0 in competition with catalase and the product, diperoxovanadate, resists scavenger action of catalase. Diperoxovanadate can act as a substrate in a H2O2-user reaction, horseradish peroxidase and can take the place of H2O2 far more effectively in oxidatively inactivating glyceraldehyde-3-phosphate dehydrogenase. By forming peroxo-complexes vanadate can provide a way of preserving cellular H2O2 in presence of abundant catalase and make it available for its functions.

Tyrosine kinases and calcium dependent activation of endothelial cell phospholipase D by diperoxovanadate.

Reactive oxygen species (ROS) mediated modulation of signal transduction pathways represent an important mechanism of cell injury and barrier dysfunction leading to the development of vascular disorders. Towards understanding the role of ROS in vascular dysfunction, we investigated the effect of diperoxovanadate (DPV), derived from mixing hydrogen peroxide and vanadate, on the activation of phospholipase D (PLD) in bovine pulmonary artery endothelial cells (BPAECs). Addition of DPV to BPAECs in the presence of .05% butanol resulted in an accumulation of [32P] phosphatidylbutanol (PBt) in a dose- and time-dependent manner. DPV also caused an increase in tyrosine phosphorylation of several protein bands (Mr 20-200 kD), as determined by Western blot analysis with antiphosphotyrosine antibodies. The DPV-induced [32P] PBt-accumulation was inhibited by putative tyrosine kinase inhibitors such as genistein, herbimycin, tyrphostin and by chelation of Ca2+ with either EGTA or BAPTA, however, pretreatment of BPAECs with the inhibitor PKC bisindolylmaleimide showed minimal inhibition. Also down-regulation of PKC alpha and epsilon, the major isotypes of PKC in BPAECs, by TPA (100 nM, 18 h) did not attenuate the DPV-induced PLD activation. The effects of putative tyrosine kinase and PKC inhibitors were specific as determined by comparing [32P] PBt formation between DPV and TPA. In addition to tyrosine kinase inhibitors, antioxidants such as N-acetylcysteine and pyrrolidine dithiocarbamate also attenuated DPV-induced protein tyrosine phosphorylation and PLD stimulation. These results suggest that oxidation, prevented by reduction with thiol compounds, is involved in DPV-dependent protein tyrosine phosphorylation and PLD activation.

Decavanadate possesses alpha-adrenergic agonist activity and a structural motif common with trans-beta form of noradrenaline.

Decavanadate, an inorganic polymer of vanadate, produced contraction of rat aortic rings at a relatively high concentration compared to phenylephrine, an agonist of alpha-adrenergic receptor. This effect was blocked by two known alpha-adrenergic receptor antagonists, prazosin and phenoxybenzamine. Decavanadate, formed by possible dimerization of V5 under acid conditions, possessed a structural feature of two pairs of unshared oxygen atoms at a distance of 3.12 A, not found in its constituents of V4 or V5. A structural motif of O..O..O using such oxygen atoms is recognized in decavanadate. This matches with a similar motif of N..O..O that uses the essential amino and hydroxyl groups of the side-chain and the m-hydroxyl group in trans-beta form of noradrenaline. The interaction of such a structural motif with the membrane receptor is likely to be the basis of the unusual noradrenaline-mimic action of decavanadate.

Vanadium catalysis in bromoperoxidation reaction.

Peroxidative bromination of phenol red to its tetrabromo derivative, bromophenol blue, required vanadate in addition to H202 when carried out in the pH range of 5-7. Excess H202, with ratio of H202:vanadate of 2:1 and above, prevented the reaction. Diperoxovanadate, known to be formed in such reaction mixtures, was ineffective by itself and needed uncomplexed vanadate (V(v)) or vanadyl (V(iv)) to support bromination. Bromide-assisted reduction of the excess vanadate to vanadyl appeared to be an essential secondary reaction. In the absence of phenol red oxygen was released, and concomitantly bromide was oxidized to a form competent to brominate phenol red added after termination of oxygen release. These findings indicated participation of reactions leading to an intermediate derived from vanadyl and diperoxovanadate, previously described from this laboratory (Arch. Biochem. Biophys. 316, 319-326, 1995). Continuous bromination of phenol red occurred when glucose oxidase-glucose system was used as a source of continuous flow of H202. A scheme of reactions involving peroxovanadates (mono-, di-, mu-, and bromo-) is proposed for the formation and utilization of an active brominating species and for the recycling of the product, mono-peroxovanadate, by H202, which explains the catalytic role of vanadium in the bromoperoxidation reaction.

Ethanol-dependent oxygen consumption and acetaldehyde formation during vanadyl oxidation by H2O2.

Sequential addition of vanadyl sulfate to a phosphate-buffered solution of H2O2 released oxygen only after the second batch of vanadyl. Ethanol added to such reaction mixtures progressively decreased oxygen release and increased oxygen consumption during oxidation of vanadyl by H2O2. Inclusion of ethanol after any of the three batches of vanadyl resulted in varying amounts of oxygen consumption, a property also shared by other alcohols (methanol, propanol and octanol). On increasing the concentration of ethanol, vanadyl sulfate or H2O2, both oxygen consumption and acetaldehyde formation increased progressively. Formation of acetaldehyde decreased with increase in the ratio of vanadyl:H2O2 above 2:1 and was undetectable with ethanol at 0.1 mM. The reaction mixture which was acidic in the absence of phosphate buffer (pH 7.0), released oxygen immediately after the first addition of vanadyl and also in presence of ethanol soon after initial rapid consumption of oxygen, with no accompanying acetaldehyde formation. The results underscore the importance of some vanadium complexes formed during vanadyl oxidation in the accompanying oxygen-transfer reactions.

Catalase degrades diperoxovanadate and releases oxygen.

On incubation with catalase diperoxovanadate was found to be degraded, showing a decrease in its absorbance at 356 nm and a loss of its peak with a chemical shift at -706 ppm in its 51V NMR spectrum. The products of the reaction had an absorption peak at 266 nm and chemical shifts at -569 and -578 ppm in NMR spectra assigned to dimer and tetramer of vanadate, respectively. Catalase released half the molecular equivalent of oxygen during this degradation of diperoxovanadate with a rate two orders of magnitude lower than that seen with H2O2. By substituting for and not releasing H2O2, diperoxovanadate supported scopoletin oxidation by horseradish peroxidase, as indicated by the reaction being not sensitive to catalase, unlike that seen with H2O2. Catalase-dependent oxygen release was sensitive to azide with both H2O2 and diperoxovanadate as substrates, whereas EDTA selectively inhibited this reaction with diperoxovanadate. The results bring out the potential of catalase in degrading diperoxovanadate and suggest caution in the use of this enzyme to destroy excess H2O2 during preparation of this compound.

Requirement of a diperoxovanadate-derived intermediate for the interdependent oxidation of vanadyl and NADH.

Oxygen release accompanying oxidation of vanadyl by diperoxovanadate was suppressed on addition of NADH. The added NADH was rapidly oxidized, oxygen in the medium was consumed, and the reaction terminated on exhaustion of either NADH or vanadyl. The consumption of oxygen and disappearance of NADH needed small concentrations of diperoxovanadate to initiate and increased with increase in the concentration of vanadyl and NADH or decrease of pH. The products of the reaction were found to be NAD+ from NADH and vanadate oligomers from vanadyl and oxygen. The reaction was insensitive to catalase and was not dependent on H2O2. The reaction was inhibited by superoxide dismutase, cytochrome c, EDTA, Mn2+, histidine, and DMPO, but not by hydroxyl radical scavengers such as ethanol and benzoate. The ESR spectrum of the reaction mixture showed the presence of the 1:2:2:1 quartet signal typical of a DMPO-OH adduct, but this was not modified by ethanol. This oxygen radical species, possibly of .OV type derived from diperoxovanadate, is proposed to have a role in the reactions of oxygen release and NADH oxidation.

NADH oxidation is stimulated by an intermediate formed during vanadyl-H2O2 interaction.

Addition of NADH decreased the oxygen release that accompanied oxidation of vanadyl by H2O2. The added NADH was oxidized rapidly and oxygen was consumed with a stoichiometry of 1:1 for NADH/O2. Small concentrations of H2O2 were sufficient to trigger this oxygen-consuming NADH oxidation which terminated on exhaustion of either NADH or vanadyl. The oxidation of NADH increased proportionately with concentration of NADH and vanadyl. The oxidation products of vanadyl were found to be a mixture of vanadate oligomers and peroxovanadates. The reaction was sensitive to catalase, SOD, histidine and EDTA. Using ESR spectroscopy with DMPO as the spin trap, an adduct corresponding to DMPO-OH was detected in these phosphate-buffered reaction mixtures. Participation of hydroxyl radicals in NADH oxidation, however, seems doubtful because even high concentrations of ethanol, methanol, mannitol, formate and benzoate, known to scavenge these radicals, did not block the reaction. The results indicate that peroxovanadate intermediates formed during vanadyl oxidation by H2O2 play a key role in the oxidation of NADH.