LOW LEVEL LASER THERAPY IN
OPHTHALMOLOGY
O.P.Pankov
Academic Ophthalmologic Center of Laser Academy of
Sciences of Russian Federation,
Russia, Zhukovsky
First applications of
low-level laser therapy of ophthalmic diseases began after the
investigations of L.A.Linnik with co-authors in 1976-1978 in Odessa SRI of
Ophthalmic Diseases and Tissue Therapy named after academic V.P.Philatov. For
the first time the authors managed to fix experimentally the fact of the
increasing DNA syntheses in the nuclei of ganglionic cells of retina under the
influence of low-level laser therapy, which results in the increasing cell
resistance to the influence of unfavorable factors and the rise of their
functional activity.
The authors were also the first to fix the increasing functional activity of
the epithelium and endothelium of the cornea, and the epithelium of the front
bursa of lens.
This research caused further elaboration of clinic methods of
low-level laser therapy
of ophthalmic diseases and their experimental basis.
M.M. Krasnov with co-authors offered the method of the stimulation of the
area of macula lutea in cases of dry maculodystrophy by 2-3-minute illumination
by a parallel non-focused beam of helium-neon laser, working in the modulation
mode (the frequency of pulse repetition is 10 Hz), with outlet power 0.25 mW. No
more than 3 sessions with 7-10 days interval are held. When the mentioned above
method of helium-neon laser stimulation is applied 93% of the patients with dry
dystrophy of macula lutea show the increasing visual acuity of different degree,
the improvement of the macular tests indexes, the increasing volume of the
modulate critical frequency of the fusion of the light flickering.
G.A.Uldanov (1982) established a sure speeding up of the visual function
regeneration of the patients operated on amotio retina, resulting from the given
courses of helium-neon
laser
stimulation (10-15 everyday sessions with the 1-2 minutes exposition).
There is information about positive results of
laserstimulation with the use of low-level helium-neon and argon lasers with
functional amplyopia of various genesis (E.A.Avetisov and others, 1977).
A.I.Zolotareva, A.F.Belyanin (1982) publish the observation of the results of
helium-neon laser application (outlet power 2 mW, the power density of the
surface of cornea 0.1 mW/cm2) to 56 patients with false traumatic and
hemolytic nonmophthalms with the case history from one day in some cases to
several months, with the visual acuity within the limits of photoperception and
the lack of reflex from the eyegrounds. After the course of
laser therapy (6-10 everyday 1-3-minute sessions), 49 patients showed the
improvement of the optic characteristics of the vitreous body, 43 developed a
subject vision. In long terms (up to 2 years) 31 observed patients (from 42)
with false and hemolytic nonmophthalms showed the improvement of visual function.
The first publication about the positive effect of the helium-neon laser
application in the treatment of flabby-going post-traumatic iridocyclitis and
long-healing ulcers of the cornea belongs to V.D. Starodubtsev (1979).
A.D.Semenov with co-authors (1979) was one of the first who informed about the
successful use of helium-neon laser (density power 0.05 mW/cm2) in
the treatment of cornea dystrophy, appearing after the operation on the eyeball.
The cornea was subjected to 3-5 minute irradiation, and so were healthy
perilimbus zones 3-5 mm wide. The course of treatment consisted of 8-10 sessions
with a day interval. The courses were repeated in 3-6 months. Under the
influence of laserstimulation the pain disappeared in the eyes of 91% of
patients, visual functions of 75% of patients improved, 81% of patients had a
complete or partial restoration of the cornea sensitivity. In long periods (3-4
years) a steady curing effect of 64% of the examined patients was observed. The
best results were obtained with laserstimulation of the dystrophic process of
cornea on early stages (up to 6 months from its start).
In the following works of different authors there has been noted a high
effectiveness of the application of low-level helium-neon laser therapy in the
complex treatment of patients both with endothelial-epithelial dystrophy and
traumas, burns of cornea. manifesting itself in the restoration of limpidity and
sensitivity of the cornea, the increasing visual acuity and earlier completion
of regenerating processes compared to the control group of patients.
Experimental research stated that low-level helium-neon laser therapy with
the density of power flow 0.05-0.1 mW/cm2 with the exposition from 1
to 10 minutes aids the activation of proliferate and regenerative processes in
the cornea in the case of its injury and doesn't cause irradiation injury of the
retina.
According to the observations of L.A.Linnik and P.P.Chechin a successive
combined use of low-level radiation of argon and helium-neon lasers influences
much more effectively (than the use of only helium-neon laser) on the
stimulation of reparative processes in the cornea in cases of its hard injuries,
in particular, of long-healing ulcers.
Almost all above-mentioned publications note that the use of low-level laser
therapy in the treatment of ophthalmic diseases didn't cause any local or
general complications. But experimental investigations showed the possibility of
unwanted side effects of the eye laserstimulation. Thus, G.L.Ukhaneva with
co-authors (1985) registered edema and destruction of external layers of retina,
and also the increasing intraocular pressure from 26-29 mm Hg with the effect of
lymphostasis in the membranes after the irradiation of a rabbit eye by
helium-neon laser with the power 1 mW. It is established that the influence of
the energy of the radiation of the low-level helium-neon laser on the peripheral
part of the visual analyzer of the females of white non-linear rats of sexual
mature age results in the change of their sex cycle, the increasing number of
abortion. They also inform about the case of decompensation of intraocular
pressure of a patient with hyphemia on an eye after a single 1-minute
irradiation by helium-neon laser with density on the cornea not more than 0.1
mW/cm2 (O.B.Chentsova with co-authors, 1988).
Experimental study of lymphostirnulating laser radiation
on the development of dystrophic changes in eye tissues.
Experimental investigations of V.AXashuba and A.V.Cherkasova, 1988) proved
that during the irradiation of an eyeball by helium-neon laser (wavelength 0.63
ìm) the radiation penetrates into retrobulbar tissues. Coming out of an eye
radiation has a directed-dispersed character. In the total, the back hemisphere
of an eyeball transmits up to 15% of laser radiation. The luminescence of the
optic nerve indicates that nerves also serve as certain conductors of light, and
their optic characteristics may influence the transmission of nerve impulses.
Coming through eye-surrounding soft tissues and ossa cranii laser radiation
reaches the cerebral cortex (0.2-0.9% at every measured point).
So, relying on the above-listed experimental and clinic data one can assume
that laserstimulation of the front part of eyes also activates the drain of the
back parts of retina and optic nerve, clearing the neuroreceptor system from
metabolic product, thus preventing the development of dystrophic changes in
retina and optic nerve.
To prove this hypothesis, we carried out an experimental study of the eye
neuroreceptor system condition according to the data of computer
electroretinography on our experimental model of dystrophic form of myopia.
There were conducted 2 series of experiments (16 eyes, 8 rabbits, 8 eyes in
each series). In the first series of experiments the rabbits developed myopic
disease under the influence of provoking enzyme (papain) administered into the
zone of an eye equator. In the second series of experiments immediately after
the administering of the enzyme the zone of the equator was irradiated by a
helium-neon laser with the outlet power density 0.5 mW/cm2. The
irradiation was repeated twice with a 3-day interval. After 6-12 months of
observation in the second series under "the protection of laser radiation" the
myopic disease didn't develop. The computer ERG showed that in 6 months after
the beginning of the experiment the retina of the experimental animals didn't
develop dystrophic changes according to ERG data. And in the control series
there was registered a clear 40-60%o decrease of the amplitude of the wave "v"
of the electroretinogram compared to the experimental group.
In the retina of the experimental eyes one can note the decrease of neurone
density in the external nuclear layer, the distortion of the structure of the
external segments of photoreceptors, especially in reactive thinness of sclera,
edema in the layer of ganglionic cells. As in the optic nerve, low-level laser
therapy shows its stimulating effect on the substituting vegetation of glial
tissue in the injured retina. One should note the therapeutic effect oflow-level
laser sources, manifesting itself mostly in injured tissues of an eyeball.
The study of gernodynamics by the method of rheoophthalmology in the I series
of experiments confirmed the progressing lowering of the ROG compared to the
second series of experiments where the ROG amplitude was close to the norm. Thus,
our research showed the protective action oflow-level laser therapy on the
development of dystrophic processes
The clinic research of lymphatic drain of the eye under
the influence of
low-level laser therapy according
lo lymphoangiography data.
Totally 26 eye of 15 patients with dystrophic diseases of the organ of vision
(dystrophy of retina, atrophy of the optic nerve, glaucoma, high complicated
myopia) were subjected to laserstimulation. Their vision acuity, visual field (including
he study on the peritest), macular tests were studied in dynamics. The function
of lymphatic system was studied in dynamics by lymphoangliography of bulbar
conjunctiva according to the method of Shmyireva V.F. and Fridman N.V. Totally
63 lymphoangiographic studies were carried out in 26 eyes (before
laserstimulation, immediately after the session and in dynamics after the course
of laserstimulation.
Results. On the second day after the laserstimulation
session all patients demonstrated subjective improvement of vision. The analysis
of the eye acuity study showed that after the course of laserstimulation it
increased in 24 eyes, in one eye it remained the same and in one eye it lowered
from 0.7 to 0.5. The improvement of the visual acuity is clearly manifested in
cases of the initial visual acuity 0.3-0.5. Thus in the case of the patient with
maculodystrophy it increased from 0.5 to 1.0, and in the case of the patient
with glaucoma of III-IV degree the visual acuity increased from 0.01 to 0.1. The
indexes of macular tests improved in 25 eyes (from 26).
Patients with glaucoma when tested on peritest demonstrated the decreasing
quantity of microscotomas after the course of laserstimulation. The vision field
expanded in all studies and in some cases - considerably.
The biomicroscopic study of the microcirculatory bed of conjunctiva after
laserstimulation demonstrated the contraction of ischemic avascular zones, the
trichangiectasia and venulectasia, distinct appearance of additional quantity of
functioning rnicrovessels.
Of a special interest for the understanding of the laserstimulation mechanism
are the results of the study of lymphocirclilation in these eyes. Thus,
immediately after the laserstimulation session, all characteristics of
lymphocirclilation (pic. 3) increased, beginning with the growing quantity from
2.09±0.41 to 2.45±0.56) and the calibre of lymphovessels (from 0.15± 0.02 to
0.23±0.05) and ending with the speed of lymphocirculation which increased almost
twice (from 1.67±0.49 to 3.03±1.71 mm3/min.). The given changes were
found in all eyes. The volume speed of lymphocirclilation after laserstimulation
in some cases was 37 and even 60 times more than the initial one.
After the course of laserstimulation the characteristics of lymphocirculation
have a tendency to decreasing. The quantity oflymphovessels decreased from
2.09±0.41 to 1.36±0.58, their average calibre - from 0.13±0.02 to 0.10±0.01, the
linear speed of lymphocirculation - from 3.44±1.06 to 2.17±0.88. The volume
speed of lymphocirculation - the integral characteristic of lymphocirculation,
after the course of laserstimulation was practically on the initial level - from
1.67±0.09 to 1.90±0.56 mm3/mm.
Discussion. Thus, based on lymphoangiographic research, we
discovered a new biologic phenomenon - the activation of lymphocirculation in
the conditions of pathology under the influence of organized laser therapy.
Alongside with it, it was established that immediately after the session of
laser therapy the intensification of lymphocirculation takes place - the
increasing of quantity and calibre of functioning lymphatic vessels and the
speed of lymphocirculation. And the decreasing of the lymphocirculation
intensity indirectly indicates the decreasing need of the eye tissues in
lymphatic drain during the process of step-by-step regeneration of visual
functions.
The perspectives of the development of low-level laser
therapy in ophthalmology.
Extremely slow introduction of low-level laser therapy into the practice of
ophthalmologists is restricted by the lack of good methodological recommendation
and modern equipment adopted to the needs of ophthalmology. The most perspective
is considered to be further improvement of the methods and the elaboration of
the medical equipment, working in several wave bands (infrared, red, green and
blue), combined with magnitotherapy and working with the use of various modes of
the modulation of the intensity of the luminous flux. It may be asserted that
unlike the mode of continuous radiation, in some cases, the effectiveness of the
treatment increases when the modulated light with the frequency of one to a few
tens Hz is used. Moreover, the methods are being elaborated, when the modulation
frequency of laser light and the biorhythms of man physiologic parameters (heart
activity, respiration, visual perception) are synchronised. Very perspective
seems the computerisation of the treatment process with the simultaneous
electrophysiologic control of the condition of visual functions.
