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Dynamic Electroneurostimulation after Excimer-Laser Operations by the LASEK technology

S.A. Korotkikh, V.S. Korotkikh, S.V. Petrov

Ural State Medical Academy, Scientific and Experimental Center “Ophthalmology”, Ekaterinburg

We have studied an influence of dynamic electroneurostimulation (DENS) on engraftment of the corneal flap after excimer-laser operations, possibilities of increasing functional results and reduction of the rehabilitation period in 30 patients. DENS influence on some ophthalmo-ergonomic indexes (accommodation reserve, low-contrast vision acuity, low-contrast sensitivity), which influence the visual efficiency in the postoperative period, was studied. DENS was applied during the post-operative period using the “ViDens” apparatus. The control group consisted of 30 people who did not have DENS during the postoperative period. It was proved that after excimer-laser operations DENS has an associated multicomponent effect. It has an apparent analgesic and anti-edema action, results in enhancement of engraftment of the corneal epithelial flap, better regeneration of the cornea, improvement and faster restoration of visual functions, provides for increase and speedy stabilization of the refractive effect, increase of its forecast accuracy.

Nowadays excimer-laser surgery is the ground for carrying out refraction operations for myopia correction. The main methods are the following: LASEK (EPI-LASIK) and LASIK (INTRA-LASIK). Any surgery has certain disadvantages, which can include pain syndrome in the early postoperative period, defective engraftment of the corneal flap as well as long-term restoration of visual functions, which influence the visual capacity. In the scientific literature much attention is paid to the problem of engraftment of the corneal flap after excimer-laser operations [5,9].

The connection between the speed and character of the engraftment of the corneal epithelial flap and degree of its transparency later is proved, which in its turn influences the refraction result of the operation carried out [2,3]. Estimation of professional abilities of the organ of vision in patients after refraction operations is also of great interest. Some authors mention that some functions such as low-contrast vision acuity, spatial contrast sensitivity to blinding are restored after the operations within the periods up to 6 months. Transitory “syndrome of the dry eye” and some other complications are a big problem of the modern refraction surgery. The bulk of practical investigations are connected with drug therapy of these complications.

In addition to the above, ophthalmology knows application of electrostimulation for treating different pathologic processes [1,4,6,8,10]. Favourable influence of electrostimulation on solving many problems is noted.

Goal of the Work.

To study influence of dynamic electroneurostimulation on engraftment of the corneal flap after excimer-later operations by LASEK technology and abilities to improve functional results as well as reduction of the period of visual functions rehabilitation which is of special importance for occupations making higher demands to the visual analyzer.

Materials and Methods.

DENS results after refraction operations for myopia were studied in 30 patients (60 eyes), of which 15 men (50.0 %) and 15 women (50.0 %) in the age 23-47 years (on average 30.4±0.8 years). Degree of myopia was from -0.5 to -16.0 dioptres, average value was -9.79±-0.25 dioptres. The patients in the main and control groups were chosen in such a way that myopia degree, corneometrical data and character of the operation were approximately the same. Excimer laser MEL-60 (Germany) was used for operations. DENS-therapy started to be applied from the 1st day after the operation, treating the following zones: paraorbital zone in the MED program and in the THERAPY mode at frequency 77 Hz during 10 minutes, cervical-collar zone – in the TEST mode with treatment of the found latent trigger zones in the THERAPY mode at frequency 77 Hz during 3-5 minutes per each zone, total Nos. 12-14.

To assess the results in the main and control groups the following examination was carried out:

- examination of the visual acuity with correction;
- examination of low-contrast visual acuity with help of the projector of testing signs Carl Zeiss Jena under 18 % contrast;
- reserve of relative accommodation;
- periods and quality of engraftment of the corneal flap and subjective sensations.

Results and Discussion.

In all patients of the main group an apparent analgesic effect was registered – intensity of pain was less and the pain was relieved earlier than in the patients of the control group.

There were no intolerance of procedures, allergic reactions in the main group registered. Special attention was paid to the degree of intensity of the postoperative reaction. In the main group the degree of the corneal syndrome intensity was less and engraftment of the corneal epithelial flap faster.

Two variants of engraftment of the corneal epithelial flap were found: favourable – full engraftment.

Unfavourable – small edge defect of the flap with edematic edges and areas of loose and movable joining.

In all eyes of the main group who had DENS-therapy, favourable variant of cornea epithelization (100 %) was registered.

In the control group who had no DENS, a favourable variant was registered in 47 (78.3 %) eyes. In 13 eyes (21.7 %) an unfavourable variant of engraftment of the corneal epithelial flap was registered which was accompanied by corneal syndrome. A direct relation between degree of edema of the cornea epithelium and character of its healing was registered. The more pronounced was the edema the worse was the healing.

Periods of engraftment of the corneal epithelial flap in the main group were less than in the control group. Periods of engraftment of the corneal epithelial flap in the main group in 100 % of cases were no longer than 48 hours, whereas in the control group only 37 eyes (61.7 %) had engraftment within 48 hours, 21 eyes (35.0 %) – during 72 hours, and 2 eyes (3.3 %) had engraftment within later periods.

Table 1. Periods of Engraftment of the Corneal Epithelial Flap in the Main and Control Groups

Time of Examination	DENS (60 eyes)		Control (60 eyes)
	Amount of eyes	%	Amount of eyes	%
48 hours 72 hours >72 hours	60                 100  - - - -		37                  61.7 21                  35.0 2                     3.3

Vision acuity restored earlier in eyes in the group which had DENS. The difference was the most apparent during the first week of observation.

Within one week and one month vision acuity with correction was also higher in the main group. We also think it is important to note the fact that uncorrectable vision acuity one month after the operation was higher than the maximum correctable vision acuity before the operation in both groups.

The table Dynamics of the Vision Acuity below shows the data with statistical validity, P< 0.05.

Table 2. Dynamics of the Vision Acuity in the Main and Control Groups

Time of Examination	DENS (60 eyes)	Control (60 eyes)
Before the operation 1 week 1 month	0.73+0.01 (with max. correction) 0.64+0.01 0.86+0.02	0.73+0.01 (with max. correction) 0.57+0.01 0.85+0.02

As myopic eyes initially have lower functional abilities than emmetropic eyes, an important task for having a good refraction result after the operation is to increase these functions (such as reserve of accommodation, low-contrast vision acuity, spatial contrast sensitivity) [7 ]

The fact that low-contrast vision acuity in the control group after the operation reduces and restores to the initial level only one month after the operation is of particular interest. In the group which had DENS this index exceeded the level before the operation.

Reserve of accommodation in the group which had DENS both one week and one month after the operation was higher than in the control group. The data given below have statistical validity, P< 0.05.

Table 3. Dynamics of Low-Contrast Vision Acuity and Accommodation Reserve in the Main and Control Groups

Conclusions.

1. DENS-therapy after excimer-laser operations has a positive multicomponent effect. It has analgesic and anti-edema effect, accelerates the period of engraftment of the corneal epithelial flap, reduces the risk of complication which influence the optical result of the operation.
2. DENS promotes faster restoration and improvement of visual functions, having direct influence on refractive effect of the operation and faster restoration of visual capabilities.
3. DENS is an efficient factor of increasing the effectiveness of excimer-laser operations. Simplicity and convenience of applying “ViDens” complex allows recommending it to patients for having treatment course at home for the purpose of improvement of visual functions.

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