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Владимиров Д.В. Аберрометрический анализ оптической системы глаза с помощью программы Vector aberrations
29.05.2014, 08:40

Резюме
Владіміров Д.В. Аберометричний аналіз оптичної системи ока за допомогою програми Vector aberrations.
Проаналізовано дані аберометрії оптичних систем офтальмологічно здорових волонтерів, а також пацієнтів після факоемульсифікації з імплантацією різних типів ІОЛ. Пацієнти розподілені на чотири групи. Перша – здорові волонтери; друга – пацієнти з імплантованими сферичними ІОЛ; третя - пацієнти з імплантованими асферичними ІОЛ; четверта - пацієнти з імплантованими мультифокальними ІОЛ. Аберометрію пацієнтам 2-4 груп виконано в строк 3 місяці після факоемульсифікації. Всі дані оброблені за допомогою програми Vector aberrations, яка дає можливість розкласти СКВ хвильового фронту на радіальну та тангенційну компоненти, а також знайти їх відношення. Введення в оптичну систему штучного компонента (ІОЛ) значно впливає на її якість.
Ключові слова: аберометрія, СКВ хвильового фронту, ІОЛ, Vector aberrations, факоемульсифікація.
Резюме
Владимиров Д.В. Аберрометрический анализ оптической системы глаза с помощью программы Vector aberrations.
Анализу подверглись оптические системы офтальмологически здоровых волонтеров, а также пациентов после факоэмульсификации с имплантацией различных типов ИОЛ. Пациенты разделены на четыре группы. Первая – здоровые волонтеры; вторая – пациенты с имплантированными сферическими ИОЛ; третья – пациенты с имплантированными асферическими ИОЛ; четвертая - пациенты с имплантированными мультифокальными ИОЛ. Аберрометрия пациентам 2-4 групп выполнена в срок 3 месяца после факоэмульсификации. Все данные обработаны программой Vector aberrations, которая дает возможность разложить СКО волнового фронта на радиальную и тангенциальную составляющие, а также найти их отношение. Введение в оптическую систему искусственного компонента (ИОЛ) значительно влияет на ее качество.
Ключевые слова: аберрометрия, СКО волнового фронта, ИОЛ, Vector aberrations, факоэмульсификация.
Summary
Vladimirov D.V. The aberrometry analysis of human eye optical system by using “Vector aberrations” software.
There were analyzed the optical systems of healthy volunteers and patients after phacoemulsification with different IOL types implantation. All patients divided on four groups. 1st – healthy volunteers; 2nd – patients after phaco with spherical IOL implantation; 3rd - patients after phaco with aspherical IOL implantation; 4th - patients after phaco with multifocal IOL implantation. In 2-4 groups aberrometry were performed in terms of 3 month. All data were processed with Vector aberrations software. This program performs RMS splitting onto radial and tangential components. Introduction of artificial component (IOL) into optical system becomes it negative quality shift.
Key words: aberrometry, RMS of wave front, IOL, Vector aberrations, phacoemulsification.
Рецензент: д.мед.н., проф. А.М. Петруня

УДК 617.726 (048.8)

Киевская городская клиническая офтальмологическая больница "Центр микрохирургии глаза"

Kyiv City Clinical Eye Hospital "Eye Microsurgery Center"

oko_66@mail.ru

One of the most important factor in successful correction of visual disorders is information about eye aberration status. Discovering eye optical system requires analysis of many units, and components affecting the aberration of the optical system [1, 2, 3]. These include, in particular, the deviation of the optical beam axis. Often, incoming rays do not cross the reference axis. This fact is not new, but it has not established yet which of the errors of the optical system is responsible for it. [4] For measurements of such deviations serves ray tracing aberrometer, but the math and the relationship calculating of radial deflection of the beam to the tangential so far not been investigated by anyone. For this purpose, a new soft “Vector Aberration” was developed by professor V.V.Molebny and G.A.Pavlovich in National Technical University of Ukraine "Kiev Polytechnic Institute" [5]. The main advantage of this program is a new approach to the calculation of the standard deviation (SD) of the wave front produced by scanning. This software splits RMS of wave front into radial and tangential components. Then calculate their ratio, thereby calculating how many moves the beam in three dimensions from the plane of its entry into the optical system and on its "settlement" of intersection with the reference axis. Additional features of the program includes the ability to display data in a 3D format and transfer them to the program of statistical processing.

Aim. Comparison of the results of aberrometry assessment of the human eye optical system of volunteers and patients after cataract surgery with different types IOLs implantations.

Materials and methods. To meet the goal in the study we analyzed the aberrometry charts of healthy volunteers and patients after phacoemulsification performed with intraocular lens implantation. All participants are divided into four groups. First - healthy volunteers - 98 people (196 eyes). Second - patients after phacoemulsification with implantation of spherical IOL (SN60AT, SA60AT, MA60AT) – 65 people (65 eyes). The third - patients after phacoemulsification with implantation of aspherical IOL (SN60WF) - 55 people (55 eyes). Fourth - patients with multifocal IOL (SN6AD1, SN60D3, SN60D4) - 30 people (30 eyes). All surgeries and follow up were carried out in Kiev State Ophthalmology Hospital "Eye Microsurgery Center". All eyes met the following criteria: transparent refracting surfaces, visual acuity of 0.9 or higher, the lack of concomitant ocular pathology, adequate function of the pupil. For patients in 2nd, 3rd, and 4th groups, we use the data obtained in 3 month after surgery. Furthermore in these patients there were no surgical protocol violations, errors in calculating the IOL. There were no clinically significant events during postoperative period. Aberrometry performed on ray tracing aberrometer TRACEY VFA. Scan area was 5mm. Medical mydriasis was not used. Wave front RMS data was processed by “Vector Aberrations” program. It must be emphasized that we analyzed only the third and fourth order aberrations. On (Fig.1) it is shown the aberration "mask" where the correspondent boxes are ticked.

Fig.1 Aberration "mask" in “Vector Aberrations” soft

This approach is designed to eliminate the effect of the lower-order aberrations on the final result of analysis. As to the influence of other higher-order aberrations, the quadrupeds, that the higher degree of the polynomial, the smaller contribution to the quality of the optical system makes aberration [6]

Results. Figure 2 shows a map of the RMS wave front splitting in the 1st patients group.

Figure 2. The ratio of the radial component of wave front RMS to the tangential (skew) - the 1st group.

These histograms illustrates a slight deflection of a ray tracing optical system, which ultimately causes high visual acuity. The ratio of the radial component to tangential (both calculated in microns) is equal to 2.11.

The following diagram (Figure 3) shows a map of the RMS wave front splitting in the 2nd patients group.

Figure 3 The ratio of the radial component of wave front RMS to the tangential (skew) - the 2nd group.

These data suggests a significant rays deviation during passing modified (spherical IOL implanted) optical system of the eye, which proves the deterioration of the optical system under the influence of aberration in comparison with optical systems of the first group of volunteers. The ratio of the radial component to tangential (both calculated in microns) is equal to 2.27.

Figure 4 shows a histogram of the 3rd patients group.

Fig. 4. The ratio of the radial component of wave front RMS to the tangential (skew) - the 3rd group.

Numerical equivalent ratio of radial component to tangential is 2.21. This value is slightly smaller, and consequently, the optical system is better in comparison with that of the second group of patients, but significantly worse intact optical system of the first group of volunteers. This fact, in our opinion, is linked with a reduction of spherical aberration of the system due to the implantation of aspheric IOLs.

Figure 5 is describing the results of the wave front RMS transformation into radial and tangential components in 4th patients group, using “Vector Aberrations” soft. It is proved that the ReSTOR IOL implantation does not change the value of higher-order aberrations wherther patient looks to far or near distans [7]. Therefore, for the 4th patients group we used the far distance data of aberrometry, a distance of not less than 5m.

Figure 5. The ratio of the radial component of wave front RMS to the tangential (skew) - the 4th group.

The ratio of the radial component to tangential (both calculated in microns) is equal to 2.56. The worst result is probably related to the structure of the ReSTOR IOL. Large scanning area - 5mm - causes significant ray deviations in the human eye optical system.

Conclusions. Analysis of the human eye optical system in volunteers without ophthalmic diseases, as well as patients undergoing phacoemulsification with implantation of different types of IOLs, using the “Vector Aberrations” software showed that:

1. Introduction of artificial optical component (IOL) in human eye do greatly reduces the quality of eye optical system.

2. In case of implantation of aspheric IOL, there is some decrease of fourth-order aberrations, which positively affects the quality of the optical system (in this study).

3. “Vector Aberrations” is a new approach to understanding the genesis of higher-order aberrations. Developed program gives an opportunity to understand the influence of higher-order aberrations to visual acuity.

Литература
1. Lombardo M. Wave aberration of human eyes and new descriptors of image optical quality and visual performance / M. Lombardo, G. Lombardo // J. of Cataract & Refractive Surgery. - 2010 - Vol. 36, Is. 2. - P. 313-331.
2. Predictability of ocular spherical aberration after cataract surgery determined using preoperative corneal spherical aberration / Kazuno Negishi, Chiyo Kodama, Takefumi Yamaguchi [et al.] // J. of Cataract & Refractive Surgery. – 2010. - Vol. 36, Is. 5. – P. 756-761.
3. Predicting crystalline lens fall caused by accommodation from changes in wavefront error / Alexandre Denoyer, Ludovic Denoyer, Jérémie Halfon [et al.] // J. of Cataract & Refractive Surgery. – 2009. - Vol. 35, Is. 3. – P. 496-503.
4. Molebny V. Ocular Q-factor: an approach to eye aberrations analysis / V. Molebny, S. Molebny // Journal of Modern Optics. - 2011. – Vol. 58, Is. 19-20. – Р. 1729-1735.
5. Vector aberrations - новые возможности аберрометрии / В.В. Молебный, Г.А. Павлович, Н.М. Сергиенко, Д.В. Владимиров // Тезисы конференции «Современные достижения в хирургии переднего и заднего сегментов глаза». Киев, 2010. – С. 154.
6. Алиев А.-Г.Д. Аберрации оптической системы глаза при имплантации искусственного хрусталика / А.-Г.Д. Алиев, М.И. Исмаилов. - М., 2000. - 141 с.
7. Владимиров Д.В. Аберрометрия глаз после имплантации мультифокальных интраокулярных линз / Д.В. Владимиров // Офтальмол. журнал. - 2012. - № 6. - С. 26-30.

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