scholarly journals Power Calculation Error due to Application Program Problem

2020 ◽  
Author(s):  
Keyword(s):  
Power Calculation ◽  
Calculation Error ◽  
Program Problem ◽  
Application Program

scholarly journals Biometry in Silicone Oil Filled Eyes. A Review

2021 ◽  
Vol 18 (4) ◽  
pp. 769-777
Author(s):  
A. N. Kulikov ◽  
E. V. Danilenko ◽  
A. R. Kuznetsov
Keyword(s):  
Silicone Oil ◽  
Vitreoretinal Surgery ◽  
Power Calculation ◽  
Calculation Error ◽  
Toxic Reaction ◽  
Low Coherence ◽  
Iol Power Calculation ◽  
Significant Term ◽  
Iol Power ◽  
Silicone Oil Tamponade

The “gold standard” of modern vitreoretinal surgery is silicone oil tamponade of the vitreous cavity. The lens opacity development is in the list of complications of prolonged silicone oil eye filling (from 2 weeks to 2 years). Polydimethylsiloxanes hydrophobicity, direct contact with the front of the silicone bladder, macrophage and toxic reaction, trophic disturbances are the causes leading to the cataract initiation. This makes the problem of cataract surgery and preliminary intraocular lens calculation in silicone oil filled eyes before its removing very relevant as well as cloudy retina visualization and the necessity of minimization of number of operations through their combination. Certainly, the main error in IOL power calculation is associated with axial length measurement inaccuracy, as the most significant term of an equation. Silicone oil filled eyes biometry errors, and, consequently, postoperative refraction biases remain unresolved problem until now. To date authors report only 58 % of cases in which target refraction was achieved after combined surgery. Some researchers figure out that average calculation error after phacoemulsification with IOL implantation in avitreal eyes was 0.8 D despite of the optical biometry usage. Today it is represented by several methods: partial coherent interferometry, optical low-coherence reflectometry and optical coherence tomography, which are implemented in devices such as IOLMaster 500, Lenstar LS 900 and IOLMaster 700, which have their own characteristics and measurement accuracy. Their advantages as well as creation an accurate IOL calculation method for silicone oil filled eyes could reduce postoperative refraction error that outline significant medical and social problem.

scholarly journals Impact of Eye Drops Instillation of Antihypertensive Drugs on the Refractive Power of the Cornea

2020 ◽  
Vol 17 (3) ◽  
pp. 490-494
Author(s):  
D. F. Belov ◽  
V. P. Nikolaenko
Keyword(s):  
Antihypertensive Drugs ◽  
Open Angle Glaucoma ◽  
Tear Film ◽  
Study Groups ◽  
Corneal Astigmatism ◽  
Power Calculation ◽  
Calculation Error ◽  
Eye Drops ◽  
Refractive Power ◽  
Iol Calculation

Purpose: to assess effect of eye drops instillation on the refractive power of the cornea and potential intraocular lens (IOL) power calculation errors appearing related within.Patients and methods. There were 478 patients divided in 3 groups: 1st — patients without glaucoma and topical treatment (n = 325); 2nd — individuals with primary open angle glaucoma (POAG) on treatment (n = 122); 3rd — patients with POAG and previous trabeculectomy (TE) without using eye drops (n = 31). For each patient keratometry was performed by IOL-Master 500. Mean preoperative keratometry and corneal astigmatism were compared within IOL calculation error received by Barrett Universal II formula 1 month after phacoemulsification (PE).Results. Mean keratometry was significantly (p < 0.001) less (0.6 D) at the 1st group (44.00 ± 1.96 D) versus 2nd group (44.6 ± 1.76 D). Cancellation of topical eye drops due to TE leads to insignificant decline of corneal curvature (from 44.6 ± 1.76 D to 44.1 ± 1.59 D). There was no any difference in corneal astigmatism level between study groups (0.92 ± 2.23 D, 0.8 ± 0.59 D and 0.86 ± 0.50 D for groups respectively) as like as no distinction in IOL calculation error in these groups (–0.08 ± 0.57 D, –0.06 ± 0.6 D and 0.003 ± 0.61 D). However, men have more flatter cornea (43.6 ± 1.98 D) than women (44.4 ± 1.80 D) (p < 0.001). Mean keratometry at the age group 60–74 years was less (43.7 ± 2.3 D) than at 75–90 years (44.4 ± 1.54) (p = 0.002).Conclusion. Patients with coexistent cataract and glaucoma on treatment require special attention in IOL calculation. To avoid keratometric errors it is recommended to prescribe lubricants and change hypotensive eye drops to preservative-free analogs to form a stable tear film. 

Stopping-power determination for compound by EELS

1994 ◽  
Vol 52 ◽  
pp. 948-949 ◽  
Author(s):  
David C. Joy ◽  
Suichu Luo ◽  
John R. Dunlap ◽  
Dick Williams ◽  
Siqi Cao
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Materials Science ◽  
Average Energy ◽  
Stopping Power ◽  
Accurate Information ◽  
Power Calculation ◽  
Coulomb Collisions ◽  
Electron Energy Loss

In Physics, Chemistry, Materials Science, Biology and Medicine, it is very important to have accurate information about the stopping power of various media for electrons, that is the average energy loss per unit pathlength due to inelastic Coulomb collisions with atomic electrons of the specimen along their trajectories. Techniques such as photoemission spectroscopy, Auger electron spectroscopy, and electron energy loss spectroscopy have been used in the measurements of electron-solid interaction. In this paper we present a comprehensive technique which combines experimental and theoretical work to determine the electron stopping power for various materials by electron energy loss spectroscopy (EELS ). As an example, we measured stopping power for Si, C, and their compound SiC. The method, results and discussion are described briefly as below.The stopping power calculation is based on the modified Bethe formula at low energy:where Neff and Ieff are the effective values of the mean ionization potential, and the number of electrons participating in the process respectively. Neff and Ieff can be obtained from the sum rule relations as we discussed before3 using the energy loss function Im(−1/ε).

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