Skiascopia - a modern method for diagnosing visual disorders

In 1873, the French scientist Kunieu proposed a method for measuring refraction of the eye, later called "skiascopy" (per. from the ancient times. - "shadow "watching"). Hence the second name of the method - "shadow test".

During this survey, a special device is used - a skiascope, which is a mirror with a handle.The first surface of the mirror is convex, and the second is flat. In the central part of the mirror there is an opening through which the ophthalmologist makes measurements and observes the state of the patient's eye.What is the essence of this method? Who is shown the sciascopy?

Method definition

Under skiascopy is meant a method whose purpose is to check the functional state of the organs of vision from the point of view of their ability to refract light (refraction).Two structures respond to the refraction of the eye - the lens and the cornea. With the help of this procedure, the degree of disturbances is determined even when the human disease is simulated. Also, this method will be useful for investigating refraction in a child or a mentally retarded patient. In these cases, it is not possible to conduct conventional visometry or refractometry.

Synonymic names of the method are retinoscopy and keratoscopy.

Skiascopia is a common technique with such advantages as:

• Accuracy of results.And it is very important for revealing the cause of the eye disease and diagnosing the doctor.
• Painless.The examinee does not have any painful sensations during the examination, which is very important in cases of carrying out the examination in the child.
• Simplicity.This procedure does not require the presence of complex medical equipment. Everything is quite simple, and the accuracy of the results depends only on the ophthalmologist's professionalism. The doctor watches the patient's reactions and draws certain conclusions. The patient, on the other hand, simply sits on a chair and follows the doctor's instructions.
• Economic benefit for patients.This procedure is inexpensive even in private clinics, since it does not require the use of expensive equipment.

Sciascopia is the most accurate and objective way of examining the refraction of the eye, the results of which are especially important in the professional selection or determination of a person's ability to work.

Kinds

The method of skiascopy involves the use of one of two techniques. Let's consider each of them further.

Cylindroskiascopy

This technique allows you to accurately determine the degree of astigmatism.After the usual skysaskopii per person wearing glasses with lenses, selected specifically for him. Further, astigmatic and spherical lenses are installed opposite the examined organ of vision. The shadow is neutralized in the main meridians. Then the standard procedure of skiascopy is repeated, but with one nuance: the mirror is first guided along the axis of the astigmatic lens, and then - along the active cross-section.In the event that the shadow disappears when moving along the axis, the ophthalmologist selects the appropriate astigmatic cylinder for the patient.If the shadow does not disappear, then the cylinder is selected by means of perpendicular motion.

Study with a wide pupil

The second technique - a study with a wide pupil - is mainly used to more accurately determine the refraction in children. Preliminarily, the child is digested with short-range mydriatica (Tropicamide, Midratsil, Irifrin), which allows a more accurate assessment of the degree of true refraction.

Irifrin drops are used to dilate the pupils

The methods of skiascopy give rather good diagnostic results, however, if possible, ophthalmologists recommend examination of the organs of vision using refractometry.

Indications for conduction

The method of sciascopy is used for examination of adults and children. It is based on obtaining objective data and provides accurate results.

Skiascopy is performed in patients with ophthalmic diseases such as:

• Myopia(myopia);
• Hypermetropia(farsightedness);
• Astigmatism.

  vision problems

A skiascopy is performed both to determine the refraction of the eyes and the rate of progression of the disease, and to determine visual disturbances that were not previously identified.

The least method of skiascopy is suitable for examining patients with suspected astigmatism, since the information obtained at the conclusion of this procedure is not sufficiently informative. Such patients are recommended for further examination.

The technique we are considering is very useful in the case when the patient simulates a visual impairment.After the skiascopia, the oculists get accurate results and identify the simulator.

Skiascopy is also used for examination of children's eyes. This method is also indicated for patients with intellectual disabilities. After the termination of procedure the doctor puts the exact diagnosis and informs on it to relatives.

Contraindications to a skiascopy are:

• The presence of mental illness in patients and objectively unbalanced behavior;
• The state of drug or alcohol intoxication;
• Photophobia;
• Allergies to Atropine or Cyclodol;
• Child age is less than 7 years;
• Glaucoma.

Process of procedure

In the absence of contraindications, the patient is instilled with a cycloplegic drug (Cyclodol or Atropine) in a conjunctival sac.Then the patient is left alone until the eye muscles are completely relaxed and the pupil is dilated.

Atropine is able to cause an acute attack of glaucoma in patients with hypermetropia and in people older than 60 years.

Then the patient is asked to sit on a chair in a darkened room. At the same level as his eyes, place the lamp. The oculist sits opposite the patient in 67 cm - 1 meter in front of the patient.

Sciascopy procedure

The method of this survey is instrumental.An ophthalmologist uses a special device called a ski-scapegraph. This device resembles a mirror: on the one hand it is concave, and on the other - flat. The doctor directs the lamp to the mirror, so that the beam through the pupil has got on the fundus, which is illuminated in red. Small turns of the mirror, performed by the doctor, lead to the appearance of shadows moving in different directions. An ophthalmologist on their movement and determines the presence of normal refraction or visual disturbances (hyperopia, nearsightedness or astigmatism).To determine the degree of refraction of the eye, a special skiascopic ruler is used, which is a set of concave and convex lenses of different refractive power.

An example of a skiascopic ruler

results

The decoding of the result is due to which mirror was used - concave or flat. Possible results of using a flat mirror:

• The displacement of the reflex and the mirror in the same direction confirms normal refraction (emmetropia), nearsightedness (myopia) of mild degree before, D or farsightedness (hypermetropia);
• The displacement of the reflex in the direction opposite from the displacement of the mirror signals a possible near-sightedness of a weak degree.

The use of a concave mirror makes it possible to reveal the opposite relation between the displacement of the reflex and the mirror.

The interpretation of the result necessarily includes indicators of the degree of refraction failure.For the purpose of its detection, the subject is offered to work with a tool such as a ski-scopic ruler, on which are placed lenses with different degrees of refraction (the so-called, positive and negative diopters). Then the patient alternately applies them to the eye.The procedure continues until the motion of the shadows on the fundus stops.Thus, the results obtained will accurately indicate the level of visual acuity disturbance.

Video

conclusions

Today skiascopy is the optimal diagnostic method, which allows to reliably diagnose the type and degree of refractive error of the eyes. The effectiveness of this method is the basis for the selection of corrective lenses and glasses.

The main advantage of the method of skiascopy is accessibility, safety and simplicity. It is impossible to conduct such diagnostics independently, as the result does not depend on instruments and equipment, but on the knowledge and experience of an ophthalmologist.