Резюме
Пономарчук B.C., Павлюченко К.П., Кефи Найссан. Функціональна рухливість окорухової системи і лабільності зорового аналізатора у хворих з макулодистрофією.
Вивчено стан функціональної рухливості окорухової системи (ФПГС) і лабільності зорового аналізатора (КЧЗМ –критична частота злиття мерехтіння та КЧПМ – критичної частоти появи мерехтіння) в різноманітних кінетичних режимах - горизонтальному (Г), вертикальному (В) и хаотичному (Х) у хворих з макулодистрофією. Показано зниження показників ФПГС у хаотичном режиме на 0,21 Гц (13,6%) в порівнянні з вертикальном та горизонтальном режимом у хворих міопіею високого ступеня, тоді як при бінокулярном досліджені ступень зниженния ФПГС склала 0,4 Гц (28,6%). Показник КЧСМ в усіх трьох режимах однаковим як при монокулярном, так і при бинокулярном досліджені та дорівнює 36,6 Гц. Показник КЧПМ складає 34 Гц, що нижче показника КЧСМ у середньому на 2,6 Гц (6%).
Ключові слова: функціональна рухливість окорухової системи, макулодістрофія, лабільності зорового аналізатора.
Резюме
Пономарчук B.C., Павлюченко К.П., Кефи Найссан. Функциональная подвижность глазодвигательной системы и лабильности зрительного анализатора у больных с макулодистрофией.
Изучено состояние функциональной подвижности глазодвигательной системы (ФПГС) и лабильности зрительного анализатора (КЧСМ –критической частоты слияния мельканий и КЧПМ – критической частоты появления мельканий) в различных кинетических режимах - горизонтальном (Г), вертикальном (В) и хаотическом (Х) у больных c макулодистрофией. Показано снижение показателей ФПГС в хаотическом режиме на в 0.21 Гц (13.6%) в сравнении с вертикальным и горизонтальным режимом сравнении у больных c макулодистрофией, a При бинокулярном изучают степень уменьшения ФПГС был 0.4 Гц (28.6%). Показатель КЧСМ во всех трёх режимах одинаков как при монокулярном, так и при бинокулярном исследовании и равен 36.6 Гц. Показатель КЧПМ был равен 34 Гц ,что ниже показателя КЧСМ в среднем на. 2.6 Гц (6%).
Ключевые слова: функциональная подвижность глазодвигательной системы, макулодистрофия, лабильности зрительного аналізатора.
Summary
Ponomarchuk V.S., Pavlyuchenko K.P., Kefi Nayssan. Functional mobility of the oculomotor system and lability of the visual analyzer in patients with maculodystrophy.
There was studied the state of the functional mobility of the oculomotor system (FMOS) and lability of the visual analyzer (CFFF- the critical frequency of flicker fusion and CFFA- the critical frequency of the flicker appearance) in different kinetic regimens - horizontal (H), vertical (V) and chaotic (C) in patients with maculodystrophy. There was shown reduction in the indices of FMOS in the chaotic regimen by 0,21 Hz (13,6%) in comparison with the vertical and horizontal regimens in the patients with maculodystrophy, while in the binocular study the degree of FMOS decrease was 0,4 Hz (28,6%). The CFFF index in all three regimens was identical both in the monocular and binocular study and was equal to 36,6 Hz. The CFFA index was equal to 34 Hz, which is lower than the CFFF index on the average by 2,6 Hz (6%).
Key words: functional mobility of the oculomotor system, maculodystrophy, lability of the visual analyzer.

УДК 617.736-007.17-053.9:617.761-073

65061, Украина, г. Одесса, Французский бульвар, 49/51.ГУ "Институт глазных болезней и тканевой терапии им. В.П.Филатова НАМН Украины"
65061, Ukraine, Odessa, Frantsuzskii Bulvar, 49/51 SI “The Filatov Institute of Eye Diseases and Tissue Therapy of the National Academy of Medical Sciences of Ukraine”

Донецкий национальный медицинский университет им. М.Горького
Donetsk National Medical University n. a. M. Gorky 83003, Украина, г. Донецк, пр. Ильича 16 Illicha Av. 16, Donetsk, 83003, Ukraine

There was studied the state of the functional motility of the oculomotor system (FMOS) and lability of the visual analyzer (CFFF- the critical frequency of flicker fusion and CFFA- the critical frequency of the flicker appearance) in different kinetic regimens - horizontal (H), vertical (V) and chaotic (C) in patients with macular dystrophy.

There was shown reduction in the indices of FMOS in the chaotic regimen by 0.21 Hz (13.6%) in comparison with the vertical and horizontal regimens in the patients with macular dystrophy while in the binocular study the degree of FMOS decrease was 0.4 Hz (28.6%).

The CFFF index in all three regimens was identical both in the monocular and binocular study and was equal to 36.6 Hz. The CFFA index was equal to 34 Hz, which is lower than the CFFF index on the average by 2.6 Hz (6%).

The keywords: functional mobility of the oculomotor system, macular dystrophy, lability of the visual analyzer.

Introduction. The sensory system of the eye transmits and processes the information obtained about the external world in the sensomotor system of the visual analyzer. The motor system has no independent value and is completely under the service of the sensory system, by which it is regulated to a considerable degree. Therefore the analysis of the eye movements is impossible without taking into account their relation to the processes of vision; on the other hand, the analysis of the visual processes inevitably leads to discussion of the role and participation of the eye movements in them.

The neuron control of the eye movements is aimed at the guarantee of accomplishment of the basic objectives of the oculomotor system − the direction of the eye to the visual target, the maintenance of the binocular vision function and spatial localization of the visual aim. [9]

The issues of terminology and classification of the eye movements have been the source of significant confusion and discussions for a long time. Lancaster W.B. [8] unified and simplified the terminology, which is accepted almost everywhere at present. According to this classification, all eye movements are subdivided into the monocular and binocular ones.

The monocular movements include all duction movements, the binocular ones − synchronous associated movements of both eyes, which, by the mutual arrangement of the visual axes in the process of the eye movements are divided into the conjugate movements of the eyes in one and the same direction − versions and movements of the eyes in the opposite directions − vergences. [8, 12, 13] The duction movements (ductions) are considered monocular, and they are the rotation of the separately taken eye. Ductions include: a) turning of the eyeball around the vertical axis Z (movement of the eye in the horizontal plane) − abduction or adduction (the eye is turned to the nose), adduction and abduction (the eye is turned to the temporal side); b) turning of the eyeball around the horizontal X axis (vertical movement of the eyeball) − supraduction or elevation (the eye is turned upwards) and introduction or lowering (the eye is turned downwards). These four movements of the eye are conventionally called cardinal [10, 11, 12]. The combination of the horizontal and vertical duction movements moves the eyeball in different oblique positions in the direction upwards - to the right, upwards - to the left, downwards – to the right, downwards - to the left. Ductions also include turning of the eye relative to the anteroposterior Y axis − cycloduction (or torsion). In this case the rotation of the front pole of the eye toward the temple is called excycloduction, toward the nose − incycloduction [3, 6, 12 13].

The eye position in the duction movements − abduction, adduction, elevation or depression − is called the second position. The oblique positions of the eyeball are tertiary.

The version movements include binocular coupled movements of both eyes, during which their visual axes are moved in one and the same direction and both eyes are moved together in the direction of the object movement. This type of the oculomotor activity includes dextroversions (turning of the eyes around the Z axis to the right), left versions (turning of the eyes around the Z axis to the left), elevations (turning of the eyes around the Y axis upwards), depression (turning of the eyes around the Y axis downwards) and cycloversions - dextrocycloversions (rotation of the eye around the X axis to the right) and left cycloversions (rotation of the eye around the X axis to the left).

The version movements accomplish two tasks, associated with the motor system of the eyes − extension of the field of vision and transfer of the object image to the fovea − and they are voluntary (at man’s will) and involuntary (semireflex movements in response to visual, sonic and other stimuli) [1, 2, 4, 5, 7].

Consequently, the search for the diagnostically significant, informative methods of determining the functional motility of the oculomotor system and lability of the visual analyzer in the kinetic regimens remains the urgent and timely scientific task of ophthalmology.

Purpose of the study - to determine the diagnostic significance of the new method of determining the functional motility of the oculomotor system and lability of the visual analyzer in different kinetic regimens − horizontal, vertical and chaotic in the monocular (ductions), and binocular (versions) study in patients with maculodystrophy.

Material and methods of the study. The studies of the functional motility of the oculomotor system (FMOS) and lability of the visual analyzer (LVA) were carried out in 26 patients including a control group (healthy people) and a group of patients with macular dystrophy.

The group of the healthy volunteers with the emmetropic refraction consisted of 10 people (20 eyes); the age ranged from 8 to 18 years old, visual acuity in them was from 1.0 to 1.5.

All patients with maculodystrophy were made a complex of the functional- diagnostic examinations: the determination of cone light sensitivity (for 7 min); the determination of the threshold of electrical sensitivity by phosphene, determination of the visual analyzer lability based on the critical frequency of the flicker disappearance by phosphene in the regimen “1, 5 and 3”; determination of the accommodation reserves by Dashevsky; determination of the activity of the fovea-cortical- afferent duct based on the phenomenon of Haidinger.

The new device - the ophthalmologic photomyostimulator (PMS), created on the base of the department of functional methods of the study, the head is Dr. of med. sciences, professor Ponomarchuk V.S. SI “The Filatov institute of eye diseases and tissue therapy, NAMS of Ukraine” determined:

1) the functional motility of the oculomotor system (FMOS) by the index of the impulse frequency movement (IFM, Hz) in three kinetic regimens: horizontal (H), vertical (V) and chaotic (C);

2) The lability of the visual analyzer by the CFFF index (critical frequency of flicker fusion) and by the CFFA index (critical frequency of the flicker appearance) in three kinetic regimens and in the stationary (fixed) regimen.

The source of PMS pulses are five light-emitting diodes of the red color (diameter of 5 mm, wavelength - 622 nm), built-in in the front panel of special glasses and located in the central zone of the field of vision of each eye. There is the possibility to establish the optimum frequency of the successive switching on of the light-emitting diodes – impulse frequency movements in two directions (horizontally and vertically) and in the mixed one − chaotic − in which the patient comfortably traces the movement of the red luminous point from one light-emitting diode to another, in the range from 0.5 to 4.0 Hz. The flicker frequency of the light-emitting diodes can be established in the range from 4 to 50 Hz in all three kinetic regimens.

The study was conducted consecutively: at first monocularly in the right eye, the left one, then binocularly. The frequency of the presented pulses of the red color gradually increased from 4 to 50 Hz. The investigated person had to note the moment of the complete disappearance of the flicker (CFFF), the CFFF index was determined in the reverse order, i.e. at the moment of flicker fusion they smoothly revolved the knob to the appearance of flickers.

There were examined the patients with the dystrophic affections of the macular zone, in particular, affection of the photoreceptor complex (pigment epithelium, median layers of the retina, vascular membranes of the eyes). Studies were carried out in Stargardt’s disease, Best’s dystrophy, progressive central dystrophy.

There were examined 16 patients with the dystrophic affections of the macular zone, mean age was 18 ± 8 years, and visual acuity in the inspected patients was 0.3 ± 0.06 and was not corrected. The diagnosis of maculodystrophy was confirmed not only by the functional disturbances, but also by morphometric, electrophysiological studies. On ophthalmoscopy the patients with maculodystrophy were observed to have foci of dystrophy in the foveal, parafoveal zone with pigmentation, the fused druses, dystrophic process with a metallic luster.

1.3.1 Functional motility of the oculomotor system of the visual analyzer in patients with maculodystrophy.

The functional motility of the oculomotor system in patients with the dystrophic affections in the macular zone was determined in the kinetic regimen (horizontal, vertical, chaotic). The IFM indices in the horizontal regimen were (2.0±0.4) Hz for the right eye, in this case the variability of the results obtained was 22%, with the minimum values of 1.0 Hz and maximum - 2.0 Hz. The IFM index in the vertical regimen was equal to (1.94±0.5) Hz, with variation coefficient of 26%, in this case its minimum value reached 1.0 Hz and maximum - 2.0 Hz. The chaotic regimen contributed to the reduction in the IFM index to (1.61±0.28) Hz, which was lower than the indices in the horizontal and vertical regimens by 0.3 Hz (19.4%) p < 0.05. It should be noted that variation coefficient for the chaotic regimen was reduced to 16.8% with the minimum values of 1.3 Hz and maximum - 2 Hz (Table 1, Fig. 1).

Table1

Indices of the impulse frequency movement (IFM) in the horizontal (H), vertical (V) and chaotic (C) regimens in patients with macular dystrophy.

Note: * P < 0.05↓ (∆) the level of significance of the differences between the IFM indices in the chaotic, and indices in the horizontal and vertical regimens. ** P < 0.05↓ (∆ ') significance of the differences between the IFM indices in the norm and in patients with macular dystrophy.

The functional motility in the monocular regimen on the left by the IFM index in the horizontal study was equal to (1.89 ± 0.4) Hz with variation coefficient of 20%, with minimum values of 1.0 Hz and maximum - 2.0 Hz. In the vertical regimen the IFM index remained at the same level (1.86±0.4) Hz with the variability variant and minimum and maximum values analogous for the right eye.

Fig.1. The indices of the impulse frequency movement (IFM) in the horizontal (H), vertical (V) and chaotic (C) regimens in patients with macular dystrophy

Note: * P < 0.05 the level of significance of the differences in the IFM indices between the chaotic and horizontal, vertical regimens in the mono- and binocular study. ** P < 0.05 the level of significance of the differences in the IFM indices between the norm and H, V and C regimens in the mono- and binocular study

In the chaotic regimen the IFM index in the left eye was equal to (1.6±0.2) Hz, which was lower by 0.28 Hz (18%) p < 0.05 in comparison with the IFM index in the horizontal and vertical regimens. Variability of the IFM index in the chaotic regimen for the left eye was also lower and reached 13% with the minimum indices 1.3 Hz and maximum - 1.9 Hz (Table 1, Fig. 1)

The comparative analysis of the functional motility of the oculomotor system in patients with macular dystrophy and the norm made it possible to reveal the degree of reduction in the IFM index in the monocular study (ductions) in the horizontal and vertical regimens, which was identical and equal to 0.67 Hz (35%), in the chaotic regimen the degree of reduction was 0.7 Hz (44%) p < 0.05. In the binocular study (versions) the IFM index compared with the norm (2.6 Hz) for the horizontal and vertical regimens, was equal to 1.98 Hz in macular dystrophy, which was lower by 0.62 Hz (31%) p< 0.05, whereas in the chaotic regimen there was noted reduction in the IFM index from 2.3 Hz in the norm to 1.69 Hz in macular dystrophy, i.e. the reduction degree was 0.61 Hz (36%) p< 0.05 (Table 1, Fig. 1).

1.3.2 Lability of the visual analyzer in patients with macular dystrophy

The visual analyzer lability in patients with macular dystrophy was investigated in the stationary (central point of fixation) and kinetic regimens (horizontal, vertical, chaotic).

The visual analyzer lability in the stationary regimen in the monocular study for the right eye by the CFFF index was equal to (32.3 ± 5.6) Hz, with the minimum CFFF values of 21 Hz and maximum - 39 Hz, the variability of indices was 17.5%. The visual analyzer lability by CFFA for the right eye had a tendency to a reduction and was equal to (30.4 ± 5.8) Hz. The minimum CFFA values were 19 Hz and maximum - 38 Hz, with variability of 19%. (Table 2).

Table 2

Lability of the visual analyzer by the CFFF and CFFA index in patients with macular dystrophy in the monocular study OD (Hz).

Note: *↓ p<0.05 the level of significance of the differences between the CFFF and CFFA indices of lability

The visual analyzer lability in the left eye by the average CFFF indices was equal to (34 ± 6.4) Hz in the stationary regimen with the minimum index – 22Hz and maximum - 41 Hz. Variation coefficient for CFFF in the stationary regimen in left eye was 18.8%. The same tendency to reduction in the index was observed on the left by CFFA, which was equal to (31.7 ± 7.2) Hz, with the minimum indices of 18 Hz and maximum - 39 Hz. Variation coefficient for CFFA was 23%. (Table 3)

Table 3

Lability of the visual analyzer by the CFFF and CFFA index in patients with macular dystrophy in the monocular study OS (Hz).

Note: *↓ p<0.05 the level of significance of the differences between the CFFF and CFFA indices of lability

In the binocular study the visual analyzer lability by CFFF was equal to (35 ± 4.8) Hz in the stationary regimen. The variability of the CFFF index was 14% with the minimum indices of 25 Hz and maximum - 41 Hz. The lability index of the visual analyzer by CFFA also had a tendency to reduction in the absolute values and on the average was 32.4 ± 4.6 Hz, variability of CFFA was also equal to 14% with minimum indices of 23 Hz and maximum - 39 Hz. (Tabl. 4)

Table 4

Lability of visual analyzer about the index CFFF and CFFA in patients with macular dystrophy before the binocular study OU (Hz).

Note: *↓ p<0.05 the level of significance of the differences between the CFFF and CFFA indices of lability

Studies in the kinetic regimen (horizontal, vertical and chaotic) allowed to determine the identical lability of the visual analyzer in right eye in all three regimens by CFFF, which on the average was equal to (32 ± 5.5) Hz, its minimum CFFF index ranged from - 21 Hz to maximum 41 Hz. It should be noted that variation coefficient for the horizontal and vertical regimens for CFFF was equal to 16%, with the chaotic one it was higher - 20%. (Table 4)

The lability index of the visual analyzer in the kinetic regimen by CFFA for the right eye was (30.4 ± 6.5) Hz with the minimum indices 16 Hz and maximum - 39 Hz, variation coefficient for the horizontal and vertical regimen was equal to 18.5% and for the chaotic one it rose to 24.5%.

The absolute lability index of the visual analyzer on the left in the monocular regimen by the CFFF index was identical in the horizontal, vertical and chaotic regimen and was equal on the average to (32.6 ± 7.0) Hz. Variation coefficient was also identical for all three regimens and was 22%, minimum CFFF value for the left eye remained the same as for the right one.

The lability of the visual analyzer by the CFFA index was in different kinetic regimens (H, V, X) and was equal on the average to (30.4 ± 7.0) Hz with the minimum values of 17 Hz and maximum - 39 Hz, with variation coefficient of 22.7%.

In the binocular study of the visual analyzer lability there were revealed the same regularity of the CFFF and CFFA indices in different kinetic regimens. The CFFF index was identical for three kinetic regimens and was equal to (34 ± 5.0) Hz with the minimum index values of 24 Hz and maximum - 41 Hz. It should be stressed that CFFF was identical for all three regimens and was equal to 15%.

The visual analyzer lability by CFFA was on the average equal to (32 ± 5.0) Hz with minimum values of 22 Hz and maximum - 39 Hz in different kinetic regimens in the binocular study. Variation coefficient remained at the same level as for CFFF - 16%.

Thus, the motility peculiarities of the oculomotor system and lability of the visual analyzer in the patients with macular dystrophy were as follows:

1. The functional motility of the oculomotor system in macular dystrophy of the retina is characterized by reduction in the index absolute values up to 1.93 Hz in the horizontal and vertical regimen, up to 1.63 Hz in the chaotic regimen, which according to the reduction degree was the same for the monocular and binocular study of different kinetic regimens and was equal to 0.65 Hz (36.5%)

2. The lability of the visual analyzer was identical in the monocular and binocular study (ductions and versions) in three kinetic regimens (H, V, X) and on the average was equal to (32.7 ± 6.5) Hz.

3. The lability of the visual analyzer by the CFFF index was identical for three kinetic regimens and it did not differ statistically significantly in the monocular and binocular study, on the average it was equal to (31 ± 5.0) Hz, i.e., the index being investigated had only a tendency to the lower level in patients with macular dystrophy.

4. The minimum index of the lability of the visual analyzer by CFFF was 21 Hz, maximum - 41 Hz, and the CFFA indices - minimum 17 Hz, maximum - 39 Hz in the monocular and binocular studies in different kinetic regimens.

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