A method for the diagnosis of keratoconus

 

(57) Abstract:

The method can be used in the field of medicine, namely to ophthalmology for the diagnosis of keratoconus. Spend aberrometry and additionally determine the activity of lysozyme in tear fluid. When values of the activity of lysozyme in excess of 21.3 g/l, diagnose keratoconus. The method allows to diagnose keratoconus in the initial stages of its manifestation; the subjective evaluation of the results of aberrometry supplemented by objective laboratory test results. 3 tab., 2 Il.

The invention relates to medicine, namely to ophthalmology, and relates to methods for diagnosing keratoconus.

Known methods of diagnosis of keratoconus by holding ophthalmometry, refractometry, mirror biomicroscopy. However, none of the known methods can not diagnose keratoconus on I, early stage of its development [1].

Closest to the invention, selected as a prototype, is a method of diagnosis of keratoconus qualitative method aberrometry, which consists in producing a point source of light through the bars of Cerning with subsequent sketch patient ovidentia aberrometry initial manifestations of keratoconus from the States after penetrating keratoplasty, radial keratotomy, mixed astigmatism, monocular diplopia. Furthermore, the method is based on the subjective perception of patients paintings gratings of Cherniga, which affects the accuracy of the diagnosis.

To Supplement the known method for the diagnosis of keratoconus by holding aberrometry the study of the activity of lysozyme in tear fluid of the patient and to determine keratoconus at specific values of the activity of lysozyme in tear fluid.

You know the concentration of lysozyme in tear fluid for study its protective bacteriological ability, based on the fact that lysozyme is a glycolytic enzyme that breaks down the polysaccharide complexes of the outer membranes of bacterial cells [4].

First established that in the early stages of keratoconus, changes in the activity of lysozyme lacrimal fluid (see tab. 1)

From table. 1 shows that the activity of lysozyme tears significantly (P < 0.01) in 2 times higher in patients with keratoconus.

The research has established that eye, suffering from keratoconus, the activity of lysozyme tears, significantly higher than in clinically healthy eye. The results of IIH keratoconus, 1.5 times higher than in clinically intact eye.

The obtained results allowed to propose a method for the diagnosis of keratoconus by aberrometry, according to which further define the activity of lysozyme in tear fluid and when it is above 21,3 mg/l diagnosed with keratoconus.

As studies have shown, changes in the activity of lysozyme tear fluid affected by keratoconus eyes appear in the early stages of keratoconus, when known methods of diagnostics, in particular aberrometry, still do not allow us to identify the characteristic disease symptoms.

Thus, the characteristic that distinguishes the inventive method from the prototype method is necessary, and in conjunction with other essential features of the proposal and sufficient to achieve new technical result - diagnosis of keratoconus in the early stages. Furthermore, the addition of the subjective evaluation analyzed the results of laboratory tests helps to increase the accuracy of diagnosis. I.e. this feature is the determination of the activity of lysozyme lacrimal fluid and the diagnosis of keratoconus at specific values of this activity is SGA development.

The analysis of publicly available literature showed that the invention is not known from the prior art, i.e., meets the requirement of novelty. Not come explicitly from the prior art, the invention involves an inventive step.

The proposed method for the diagnosis of keratoconus is as follows.

Spend aberrometry in accordance with a known method [2]. Analyzed have a point light source, through the bars of Czernina (plate diameter 37 mm round hole with a diameter of 16 mm, which is stretched in the form of a lattice of parallel wire strands with a diameter of 0.5 mm with a spacing of 0.5 mm) inserted into a socket of a test structure. Front grille installed lens, causing artificial myopia 7.0 D. normal investigated sees straight lines. In the presence of aberrations these bands twisted.

Determine the lysozyme activity of the lacrimal fluid. Tear - 0.1 ml sucked off by pipette in the lower fornix of the conjunctiva of the eyeball, pre-irritating to the nose by inhaling vapors of ammonia. From daily agar culture of Micrococcus Micrococcus Lysodecticus (strain N 2665 obtained from gisk named after. Tarasevich) preparing a suspension in phosphate buffer (pH 7,2-7,4). Suspension standardisierung buffer, 2 ml suspension of micrococci and 0.1 ml of the investigated tear fluid at a dilution of 1:4. In the control test tube researched tears do not contribute. The mixture is incubated for 30 min at 37oC, then measure its optical density to determine the activity of lysozyme in the samples in g/l [3].

When values of the activity of lysozyme in the samples exceeding 21,3 mg/l, diagnose keratoconus.

Example 1. Patient S., 19 years. 8 years is a complex sphere-cylindrical glasses. Visual acuity with glasses was constant in the range of 0.7-0.8 D for each eye. Refraction is a complex direct myopic astigmatism of 3.0 D.

Turned in LCCS with complaints of decreased vision in his right eye for the last 3 months. Vision loss associated with the death of the grandmother. My glasses visual acuity of the right eye - 0,2, left to 0.8. Maximum spectacle sphere-cylindrical correction of visual acuity has not improved.

Refractive medium of the right eye is transparent, the fundus of the eye without pathology. When biomicroscopic examination of the cornea of the right eye characteristic changes in keratoconus is not detected. Ophthalmometry revealed ukrashenie radius of corneal curvature in the vertical Meridian 6.9 mm in Gori who Atria showed the curvature of the grating bars of Cerning on the right eye (see Fig. 1). Was suspected keratoconus in the right eye. In accordance with the proposed method was investigated tear fluid on the activity of lysozyme. Right lysozyme activity was 23.4 g/l, the left - to 11.1 g/l, while remaining within the normal range. The diagnosis of keratoconus in the right eye.

The process has progressed slowly and only after 1.5 years (dynamics monitoring every 3 months.) the initial keratoconus in the right eye moved in the II-nd stage: the left eye remained intact. So it was confirmed the correctness of diagnosis.

Example 2. Patient I., 18 years. Was sent to LCCS contact correction, with complaints about non-permanent clear image in front of the right eye: the eye sees then worse, then better.

Visual acuity with spectacle correction (-6,5 D) on the right eye = 0,7, left eye = 1,0.

Upon examination of both eyes of the optical medium is transparent, the fundus of the eye within the normal range. When biomicroscopic examination of the cornea of the right eye was not detected characteristic of the initial signs of keratoconus. Indicators of ophthalmometry: the radius of curvature of the cornea of the right eye in the vertical Meridian = 7.2 mm, horizontal = 7.4 mm, however, there was some blurring of the picture marks pricheska picture of the right eye: the curvature of the two Central bands of Cerning bottom, to the left of the distortion of the bands were not detected (Fig. 2).

In accordance with the proposed method was determined by the activity of lysozyme in tear fluid of the patient. Lysozyme activity in my right eye was 25.1 g/l, on the left - 12,3 mg/L. the Patient is diagnosed with keratoconus initial stage of the right eye.

After 6 months on the right eye there was obvious signs of keratoconus stage II: visual acuity decreased to 0.02 with spectacle correction; ophthalmometry is the radius of curvature of the cornea became "cool" in the vertical Meridian is 6.6 mm, horizontal - 6.8 mm with distorted trademarks of the device; aberrometric picture - clear the curvature of the grating bars of Cerning; biomicroscopic painting stage II disease - band keratoconus.

After 2 years in my right eye keratoconus moved in the third stage, on the left - keratoconus stage II.

To confirm the objectivity of the proposed method further investigated group of patients with stage I disease (10 people) in both eyes (20 eyes). The control were 30 eyes (15 people) with refractive errors: 10 eyes with mixed astigmatism, 10 eyes with high myopia and 10 eyes after surgery, radial keratotomy. The results preopera (P < 0,05) higher than with other refractive errors. Thus, the level of activity of lysozyme in tear fluid is an objective criterion, confirming the diagnosis of keratoconus.

Thus the tests have shown that the combination of aberrometry with the determination of the activity of lysozyme tear fluid makes it possible to diagnose keratoconus in the initial stages of its manifestation.

Due to the fact that at present there is no pathogenetically justified therapy of keratoconus, the proposed method of diagnosis may be the basis for the development of such therapy.

Sources of information

1.Abugov So Early diagnosis and medical rehabilitation of patients with keratoconus means of contact correction of vision. - Diss. Kida. the honey. Sciences. - M., 1985. - 115 C.

2. Rosenblum Y. Z., Kornushina T. A. Clinical aberration of the eye// Actual problems of contact correction of vision: Sat. scient. works research Institute of eye diseases. Helmholtz RF Ministry of health. - M., 1987. - S. 66 - 70.

3. Bukharin, O. C., Vasilieva N. In. System beta-lysine and its role in clinical and experimental medicine. - Tomsk: Publishing house of Tomsk University, 1977. - 189 C.

4. Ira I., Udelt M., Abelson O. Animal and human ocular surface response to a to holding aberrometry, characterized in that it further determine the activity of lysozyme in tear fluid and when it is above 21,3 mg/l diagnosed with keratoconus.

 

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