Dynamics of charged particles in a solenoid and the accurate determination of the magnetic axis of a solenoid using measured field data.

A fundamental understanding of the theory and measurement procedures for characterizing a solenoid is crucial for making a project cost-effective and achieving the desired performance for its use in a LINAC. This paper attempts to comprehend the beam dynamics of charged particles by considering the conservation of canonical angular momentum, which can take on positive, negative, and zero values. The analytical expression to generate a parallel beam using a solenoid is derived. The effect of the final beam size on the values of a solenoid's spherical aberration coefficient and the position of the minimum beam size with respect to the focal length is studied using electron trajectories. A practical procedure to tune the above two parameters of a solenoid is demonstrated by simply modifying the demountable disks connected at each end. A mathematical model is proposed to accurately determine the axis of a solenoid and the magnetic centre using the measured magnetic field data, which is validated experimentally. Several solenoids, used in the 9.5 MeV 10 kW electron LINAC suitable for sterilizing medical products and food irradiation, have been characterised using this procedure.

Scleral tunnel phacoemulsification: Approach for eyes with severe microcornea.

Cataract surgery in eyes with microcornea is associated with frequent complications such as corneal edema, posterior capsular rent, and risk of unplanned aphakia. We describe an improved surgical technique for the creation of surgical incisions during phacoemulsification in eyes with cataract associated with microcornea. A retrospective analysis of eight patients (8 eyes) operated at our center was undertaken. The mean age of the patients was 29.5 ± 10.9 years. All eyes were operated using the scleral pocket incision for phacoemulsification. This scleral pocket incision was tangential to the limbus and created approximately 2.5 mm behind limbus through which phacoemulsification probe was inserted. Because of the posterior placement of incision, the anterior chamber crowding was minimized. There was no incidence of port-site peripheral corneal edema. Fifty percent eyes developed transient central corneal edema, the intraocular lens in bag was implanted in 5/8 eyes, and none developed Descemet's membrane detachment. Mean best-corrected visual acuity improved from 1.85 ± 0.38 logarithm of minimum angle of resolution (LogMAR) to 1.26 ± 0.70 LogMAR postoperatively (P = 0.01; paired t-test). Posterior incision placement during phacoemulsification in microcornea helps achieve favorable postoperative outcomes in contrast to outcomes using clear corneal approach described in literature.

PHACE syndrome with lip haemangioma, microphthalmos and persistent fetal vasculature.

An 11-month-old baby girl presented with white reflex in her left eye. On examination, there was a 6.5×5 mm(2)haemangioma present over her face involving on her lower lip. Systemic examinations were within normal limits. The left eye was small, with an axial length of 16.08 mm and had a cataract. Ultrasonography of the left eye was suggestive of the presence of a vascular stalk, persistent hyperplasia of a primary vitreous, or persistent fetal vasculature with vitreous haemorrhage. On MRI, the left eye was small with vitreous haemorrhage. Left eye lens aspiration was performed and the bleeding vascular stalk behind the lens was cauterised with diathermy. The right eye was normal. The patient was diagnosed as having PHACE syndrome (Posterior fossa malformations, Hemangiomas, Arterial anomalies, Coarctation of the aorta and other cardiac defects, and Eye abnormalities syndrome). On follow-up, she was able to follow light with her left eye.

Cyclodialysis-enhanced trabeculectomy with triple Ologen implantation.

PURPOSE: To describe a novel technique of trabeculectomy combined with cyclodialysis and Ologen implantation at 3 sites in cases with high risk for failure of trabeculectomy. METHODS: Six eyes of 6 patients who had high risk for failure of trabeculectomy underwent cyclodialysis-augmented trabeculectomy with Ologen implantation at 3 sites using the described technique. RESULTS: All the eyes achieved target intraocular pressure, which was maintained until 1 year of follow-up. One eye required bleb needling at 6 weeks postoperative follow-up. None of the eyes had any other intraoperative or postoperative complications. CONCLUSIONS: This novel technique of combining trabeculectomy with cyclodialysis augmented by Ologen placement at 3 locations appears to have encouraging short-term intraocular pressure control and may be adopted in eyes with risk factors for failure of conventional trabeculectomy.

Agreement between diurnal variations of intraocular pressure by Tono-Pen and Goldmann applanation tonometer in patients on topical anti-glaucoma medication.

To estimate agreement in diurnal variations of intraocular pressure (IOP) by Tono-Pen (TP) and Goldmann applanation tonometer (GAT) in glaucoma patients on topical anti-glaucoma medication(s). IOP was measured at every 3 h from 7 a.m. to 10 a.m. in 50 eyes of glaucoma patients on topical medication(s). Diurnal fluctuation of IOP by each method was calculated as maximum-minimum IOP in a day. Central corneal thickness (CCT) was measured by ultrasonic pachymeter. There was good correlation between TP and GAT at all times during a day, minimum, and maximum IOPs during a day (Correlation coefficient, 0.706 at 7 a.m., 0.624 at 10 a.m., 0.682 at 1 p.m., 0.814 at 4 p.m., 0.652 at 7 p.m., 0.572 at 10 p.m., 0.668 minimum IOP, 0.689 maximum IOP). Mean IOPs by TP were always higher than GAT at all times during a day. Bland-Altman plots suggested a close relationship between the two sets of readings, and that this relationship was consistent at different times in a day, in maximum IOPs, minimum IOPs and also in fluctuation of IOPs. Linear regression analysis between the differences of diurnal fluctuation (diurnal fluctuation by GAT-diurnal fluctuation by TP) and CCT showed strong association (R 2 = 0.857, p < 0.001). The mean change in difference of diurnal fluctuation (GAT-TP) for a 10-micron increase in CCT was 0.69 mmHg. TP can be considered a reliable alternative to GAT in glaucoma patients for knowing the diurnal control of IOP; however these two methods should not be used interchangeably. Difference of diurnal fluctuation between two methods is dependent on CCT.

Subperiosteal hematoma from peribulbar block during cataract surgery leading to optic nerve compression in a patient with parahemophilia.

A 17-year-old male presented with gradual painless diminution of vision since childhood. Slit lamp examination revealed both eyes having congenital cataract. Right eye lens aspiration was performed but was uneventful, and he prepared for left eye surgery after 7 days. Immediately after giving a peribulbar block, a complete akinesia, tight eyelids, and stony hard eyeball was noted. An abaxial proptosis of 7 mm was noted. Lateral canthotomy and inferior cantholysis were done and proptosis reduced to 5 mm. Bleeding time-clotting time was normal. Proptosis worsened to 8 mm the next day. Contrast-enhanced computed tomography scan showed inferolateral subperiosteal hematoma, but drainage could not be performed due to prolonged prothrombin time and activated prothrombin time. Fresh frozen plasma was transfused. Tarsorrhaphy was performed for exposure keratopathy after his coagulation profile became normal. Hematology evaluation after 2 weeks detected factor V deficiency, and was diagnosed as Owren's disease or parahemophilia.

Bilateral Sturge-Weber and Phakomatosis Pigmentovascularis with Glaucoma, an Overlap Syndrome.

UNLABELLED: Aim. To report a case of bilateral Sturge-Weber and Phakomatosis pigmentovascularis with secondary glaucoma in a child. Method. CASE REPORT: Results. A 4-year-old male child was referred to us for control of intraocular pressure (IOP). Sleeping IOP was 36 mm Hg in right eye and 28 mm Hg in the left eye. The sclera of both the eyes showed bluish black pigmentation-melanosis bulbi. Fundus examination of both eyes showed diffuse choroidal hemangiomas with glaucomatous cupping. Nevus flammeus was present on both sides of face along all the 3 divisions of trigeminal nerve with overlying hypertrophy of skin and on left forearm. Nevus fuscocaeruleus was present on upper trunk. All skin lesions were present since birth and were stationary in nature. CT scan of head revealed left-sided cerebral atrophy. Intraocular pressure was controlled after treatment with topical antiglaucoma medications. Pulsed Dye Laser has been advised by dermatologist for skin lesions. Patient has been advised for regular follow-up. Conclusion. The two overlapping dermatological disorders and their association with glaucoma are a rare entity. Management should be targeted both for dermatological and eye conditions.

Demographic profile, clinical features and outcome of peripheral ulcerative keratitis: a prospective study.

PURPOSE: To evaluate aetiology, demographic profile, clinical features and outcomes in cases of peripheral ulcerative keratitis (PUK). METHODS: Seventy-six eyes of 65 consecutive patients with PUK were evaluated in this prospective interventional study over an 18 month period, which were followed for 3 years. The main outcome measures were sociodemographic profile, aetiology, clinical features, management strategies and outcome. RESULTS: Sixty per cent (39/65) of cases were men and mean age was 45.5 ± 17.9 years. Two-thirds (43/65) of the patients were from rural areas with majority (48/65) belonging to low socioeconomic status. Unilateral disease was present in 83% of patients (54/65) with nasal involvement in 60.5% (46/76) cases. The most common aetiology was Mooren's ulcer (31.5% cases (24/76 eyes)) followed by infection and systemic collagen vascular disease. Meibomian gland dysfunction (17/76: 22.3%) was the most common extraocular association and complicated cataract (12/76:15.7%) was the most common intraocular abnormality. In mild and moderate cases, no significant visual improvement was observed (p = 0.085 and p = 0.156) as compared with the pretreatment status. Surgical treatment was successful in maintaining anatomical integrity in 83.3% (30/36) eyes. Recurrence of the disease was seen in one eye in moderate disease and three eyes in severe disease. CONCLUSIONS: Mooren's ulcer followed by collagen vascular diseases and infection are important causes of PUK in developing countries. Surgical intervention in perforated cases had good anatomical success and visual prognosis.

Visual field loss in primary congenital glaucoma.

PURPOSE: To assess the visual field defects in primary congenital glaucoma (PCG) and to identify associated risk factors. METHODS: In this cross-sectional study visual fields of consecutive PCG patients were examined using Humphery Field Analyzer (HFA) or Goldmann visual field (GVF). All patients had maintained an intraocular pressure (IOP) ≤14 mm Hg on standard care. Mean deviation, pattern standard deviation (PSD), foveal threshold in HFA, and global visual field extent (degrees) in 24 meridians for targets V4e, I4e, I2e in GVF were recorded and evaluated with respect to baseline IOP and age at detection. Statistical analysis was performed by Kruskal Wallis and Mann-Whitney test. Qualitative analysis of GVF and reliable fields in HFA was performed. RESULTS: A total of 100 eyes of 77 patients were included: 56 eyes of 47 patients were in the HFA group; 44 eyes of 30 patients, in the GVF group. On HFA, mean deviation detected at ≤1 month of age was significantly lower than eyes detected after 1 year (P < 0.001). On GVF, the global visual field extent for target I4e and I2e was significantly lower for PCG detected at ≤1 month of age compared to those seen at >1 year (I4e, P < 0.001; I2e, P = 0.005). Mean deviation, PSD, and foveal threshold were significantly lower in PCG with baseline IOP of >30 mm Hg than with IOP of 20-25 mm Hg (mean deviation, P < 0.001; PSD, P = 0.002; foveal threshold, P = 0.002). Extent for targets V4e and I4e on GVF were significantly lower in patients with baseline IOP of >30 mm Hg compared to those with baseline IOP of 20-25 mm Hg (V4e, P = 0.002; I4e, P = 0.003). Definitive glaucomatous defects were found in 36 eyes (41%), most ommon being arcuate scotoma (19 eyes [22%]). CONCLUSIONS: PCG detected at age ≤1 month and those having a baseline IOP of >30 mm Hg show greater visual field loss.

A safe technique for in-the-bag intraocular lens implantation in pediatric cataract surgery.

PURPOSE: To describe a safe technique for in-the-bag intraocular lens (IOL) implantation in pediatric cataract patients who undergo lens aspiration with primary posterior capsulorhexis and anterior vitrectomy. METHODS: Sixty eyes of 45 consecutive patients with congenital/developmental cataract underwent lens aspiration with primary posterior continuous curvilinear capsulorhexis (PCCC) with anterior vitrectomy and in-the-bag IOL implantation using the described technique of IOL implantation using anterior capsule as support. RESULTS: All eyes had stable IOL at the end of surgery and none of the eyes had lens decentration/dislocation in posterior vitreous. CONCLUSIONS: Implantation of in-the-bag IOL is difficult in children who undergo primary PCCC with anterior vitrectomy. Our technique of implanting IOL by pushing it against the back surface of anterior capsule is a safe method and results in no complications related to faulty IOL implantation.

IOP agreement between I-Care TA01 rebound tonometer and the Goldmann applanation tonometer in eyes with and without glaucoma.

To analyze correlation of intraocular pressure (IOP) measurement between new rebound tonometer (RBT) I-Care TA01 and Goldmann applanation tonometer (GAT). One hundred eighty-five eyes of 185 subjects presenting with glaucoma or cataract were enrolled in the study. In all patients, IOP was obtained by an ophthalmologist using I-Care TA01 and GAT. IOP between the two were compared at range of 8-15, 16-21, and >22 mmHg and difference was considered as significant at p < 0.05 (t test). Bland-Altman analysis tested agreement between instruments overall and for each subgroup of patients with glaucoma or no glaucoma (cataract only). Of 185 patients, 86 had glaucoma; 99 did not. Mean age of patients was 55.77 ± 14.46 years; with no difference between the two subgroups (p = 0.12). There was no significant difference in mean IOP between the two tonometers at IOP between 8-15 mmHg (p = 0.097) and 16-21 mmHg (p = 0.51). However, a significant difference was observed between the two at IOP > 22 mmHg (p = 0.023) with mean GAT (24.8 mmHg) being higher than mean RBT (23.16 mmHg). Overall, there was no difference between the two (p = 0.59) and they had a high correlation (Pearson correlation r = 0.815; p = 0.01). The mean difference between the two was 0.1 (95 % agreement limits: UL +6 (1.96SD), LL -5.8 (-1.96SD)), in patients with no glaucoma was 0.091 (95 % AL: UL +4.8 (1.96SD), LL -4.6 (-1.96SD)), and in patients with glaucoma was 0.151 (95 % AL: UL +7.25 (1.96SD), LL -6.9 (-1.96SD)). RBT I-Care TA01 and Goldmann tonometer cannot be used interchangeably due to large limits of agreement.

Scanning laser polarimetry in glaucoma.

Glaucoma is an acquired progressive optic neuropathy which is characterized by changes in the optic nerve head and retinal nerve fiber layer (RNFL). White-on-white perimetry is the gold standard for the diagnosis of glaucoma. However, it can detect defects in the visual field only after the loss of as many as 40% of the ganglion cells. Hence, the measurement of RNFL thickness has come up. Optical coherence tomography and scanning laser polarimetry (SLP) are the techniques that utilize the evaluation of RNFL for the evaluation of glaucoma. SLP provides RNFL thickness measurements based upon the birefringence of the retinal ganglion cell axons. We have reviewed the published literature on the use of SLP in glaucoma. This review elucidates the technological principles, recent developments and the role of SLP in the diagnosis and monitoring of glaucomatous optic neuropathy, in the light of scientific evidence so far.

Bilateral Mooren's ulcer in a child secondary to helminthic infestation of the gastrointestinal tract.

To report an unusual association of bilateral Mooren's ulcer in a child with helminthic infestation of gastrointestinal tract. A 6-year-old female presented with redness, watering and photophobia in left eye for 2 months and in right eye for 2 weeks. BCVA was 20/200 in OD and 20/400 OS. Superior peripheral corneal ulcer of 8 × 2 mm was present in the right eye and 8 × 3 mm perforated limbal corneal ulcer with staphyloma was present in the left eye. Hemogram revealed microcytic hypochromic anemia, eosinophilia and elevated ESR. No organism was isolated on corneal scraping. Stool examination revealed presence of Ancylostoma duodenale. Therapy included fortified topical antibiotics, cycloplegics, lubricants and oral albendazole. Conjunctival recession and crescentic therapeutic penetrating keratoplasty was done in OD and OS respectively. At 18 months follow up, there was no recurrence in any of the eyes. Bilateral Mooren's ulcer may be present with gastrointestinal hookworm infestation. Prompt and appropriate management may provide optimal therapeutic success.

Design and characterization of combined function multipole magnet for accelerators.

This paper presents the design and analysis of a multipurpose combined function magnet for use in accelerators. This magnet consists of three corrector magnets: (i) skew quadrupole, (ii) horizontal dipole, and (iii) vertical dipole magnets, along with the main sextupole magnet. The strength of the corrector magnets is smaller than that of the main sextupole magnet. The strength of all the four magnets can be varied independently. The excitation strength required to produce skew quadrupole gradient and the presence of various multipole components in the magnet are estimated using first order perturbation theory. The experimental data for the variation of the sextupole strength and its higher order multipoles in the presence of skew quadrupole excitations are presented and compared to the theoretical predictions. Simulation using two-dimensional fine element code, Poisson, is also done. Results obtained from all the above three methods are found to be in good agreement with each other. The variations of skew quadrupole gradient for different sextupole excitations are also measured. The validity of this theory is also checked for various combinations of excitations including the case where magnet gets saturated. The excitation strengths required for producing the horizontal and vertical dipole fields are estimated analytically along with the presence of various multipoles. Theoretical predictions of permissible multipoles are compared to the results obtained from simulation.