Ametropia

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With phoria is in optometry a hidden (also: latent ) squinting referred. This differs from other latent forms of squint in that it is determined and measured using only one examination method developed by the optician and watchmaker Hans-Joachim Haase . Another peculiarity is that only one type of treatment is recommended for a strabismus recognized in this way, namely with special prismatic lenses. In summary, this procedure is called MKH , measurement and correction method according to Hans-Joachim Haase . It is the subject of controversial discussion in the specialist world of ophthalmologists , orthoptists and opticians.

In optometric terminology, the term "ametropia" has been introduced in 1993, but it is absent in scientifically based optics. It has proven to be useful in counseling sessions there, as simple and descriptive terms (e.g. myopia for myopia, cataracts for cataracts) should facilitate communication with the customer. In addition, by avoiding the correct translation of "heterophoria" as "hidden squint" a corresponding connection to medical content is avoided and the addition of "ametropia" gives the customer a more optical-functional perspective. According to the 'Dictionary of Optometry', the terms 'ametropia' and 'associated heterophoria' have the same meaning. Thus, both terms could then be used optionally.

Disambiguation

Angular ametropia is a scientifically unrecognized term used in ophthalmic optics that is used to describe a disorder of vision with both eyes . It is therefore not an optical problem such as nearsightedness or farsightedness. The main feature of this disorder is referred to as a so-called image position error , the occurrence of which is explained by a deviation between the two visual axes. What is meant by this is the phenomenon that images of objects that a person is looking at are not projected exactly onto corresponding retinal locations in each eye , but the location of the image in one eye deviates from it to a very small extent. According to the advocates of this term, the reasons for this lie on the one hand in the assumption that the outer eye muscles of the right and left eye are of different lengths, on the other hand in an existing innervation disorder of these muscles. It is further described that affected people try to compensate for this deviation themselves and can therefore suffer from specific complaints that are commonly referred to as " asthenopia ". They manifest themselves in headaches , dizziness , burning eyes, double vision , neck stiffness, tiredness and poor concentration. Some supporters of the procedure also suspect a correlation between ametropia and dyslexia , as well as between ametropia and ADHD . To compensate for the ametropia, the adjustment of prism lenses is used, which correct the misalignment of the eyes and thus reduce or even eliminate the symptoms. Angular ametropia is not seen as a diagnosis with a disease value, but merely as a visual defect that needs to be corrected , just like myopia or farsightedness .

The ametropia is a form of associated heterophoria that has been determined exclusively using the measurement and correction methodology according to Hans-Joachim Haase (MKH) . The MKH defines the necessary test procedures on the one hand, and the evaluation of the results obtained in these tests on the other hand, and is described in the "Guidelines for the Correction of Angular Defects " published by the International Association for Binocular Vision (IVBS) . The watchmaker and optician Hans-Joachim Haase had developed this special examination and correction method at the former technical school for optics and photo technology in Berlin since the 1950s. This procedure is mainly used in the German-speaking area, as well as in the Netherlands and Italy with a comparatively very small number of opticians and occasionally also with ophthalmologists. Among the orthoptists , who have the actual core competence regarding the pathology of binocular vision due to their training and work , there is no representative who is a member of the IVBS and uses the MKH.

Scientific point of view

Evidence-based medicine and the majority of opticians not only view the concept of ametropia and especially the associated therapeutic measures very critically, but simply reject it as an "art form". Even the IVBS (International Association for Binocular Vision), as a professional association for users of the MKH, does not use the designation of amorphous vision in the current edition of its guidelines. The argument of the lack of recognized scientific evidence for the positive effectiveness of the methodology according to H.-J. However, Haase is no longer acceptable: A study on the possible effectiveness of prism correction according to MKH was published in 2015. Before and after wearing MKH prisms for several weeks, the fixation disparity was measured objectively on the one hand using high-resolution eye tracking methods and, on the other hand, using an examiner-independent, subjective adjustment method. Both the objective and the subjective fixation disparity were significantly reduced in the 24 test subjects by carrying the prism in the expected direction for several weeks, but did not decrease to zero. It is also criticized that medical concepts that have existed for a long time are only presented in a slightly modified form and above all with new terminology in order to justify an expensive corrective measure in the form of prism prescriptions: the surcharge for an individually ordered spectacle lens is the 60 EUR. A general and unreflective use of prismatic corrections is regarded as downright negligent, since improper use in some cases would have led to previously unplanned squint operations having to be performed. That is why ophthalmologists strictly reject the uncontrolled use of prism corrections as an intervention in medical treatment measures. Such a treatment or even the prospect of a certain success of the treatment go well beyond the scope of duties of opticians and represent a practice of medicine that requires permission under the Heilpraktikergesetz . On the other hand, the general rejection of prismatic corrections is comparable negligence if the person affected by asthenopia is affected by this A possible remedy is withheld from people. The "Guidelines for the Application of the MKH" describe the professional application of prism corrections as a decision that has to be made in each individual case, taking into account the measured values ​​and the complaints.

User reasoning

The proponents of the ametropia and its measurement and treatment state that there are and would have been a number of cases in which the adjustment and prescription of prism lenses led to a significant improvement, if not even elimination, of the complaint situation after a previous ametropia had been established. This would also be credibly and reliably confirmed by those affected. The MKH procedure and the treatment with prisms have existed for several decades and would be used successfully with the corresponding clients, who usually had a chain of unsuccessful attempts to experience acceptable and successful care from doctors or specialist colleagues. In addition, the discussion about the ametropia is exclusively a long-lasting professional political dispute between ophthalmologists and opticians with the background of regulating the practitioners and restricting their activities.

It is further stated that the ametropia is not an eye disease. It is just a deviation from the ideal physique. Just as a leg that is too short is not a curable disease, but can only be compensated for with a thick sole under the shoe, so a defective angle vision cannot be cured, but can only be compensated with special glasses, so-called prism glasses. In both cases, the discrepancy was only corrected as long as the corrective device 'shoe' or 'glasses' was worn. It is therefore based on the assumption that physical abuses that are incurable are not diseases.

Most people are angularly defective, but still find their vision undisturbed and have no other feeling of exertion. In these cases it is not necessary to wear prismatic glasses.

Situation of those affected

On the part of the people who suffer from the above-mentioned complaints, it is emphasized again and again that they are ultimately indifferent to the terms used to describe the cause of their health problems, as long as they are permanently and reliably relieved of them, or at least significantly reduced would. The discussion is very difficult to understand for the layperson , especially since it is always conducted in a professional manner that a patient usually hardly follows, nor with the help of which he could form a well-founded opinion. The decisive factor for a treatment decision would therefore often remain the persuasiveness of the treating optician or ophthalmologist. Even attempts to obtain further opinions before appropriate treatment often fail due to ignorance.

Comparative consideration

The following comparison is intended to illustrate whether and how the concepts and procedures of MKH, as well as the "diagnosis of amorphous vision" differ from the concepts, methods and terms of evidence-based medicine. The examination and assessment of the physiology and pathophysiology of binocular vision falls into the field of strabology (strabismus medicine), a specialty of ophthalmology .

Concept and symptoms

  • Ametropia

The concept of orthopedic ametropia is not recognized as a medical term or diagnosis and is not classified according to any diagnosis code ( ICD ). It is used as a synonym for an associated heterophoria determined by the MKH procedure . The wording “ ametropia ” generally gives the impression that there is an optical problem ( clarity , myopia , astuteness ). What is meant, however, is a disorder of the two-eyed vision (binocular vision). According to our own definition, there is an "image position error" with a deviation of the visual axes of both eyes from one another ( strabismus ). In addition, there should be a so-called “fixation disparity”, a deviation of the object image from exactly corresponding retinal locations in both eyes under fusional stress. In the effort to compensate for an ametropia, possible complaints are described that are causal and decisive for the patient's desire for treatment. These include headaches, dizziness, burning eyes, blurred vision, stiff neck, tiredness and poor concentration.

This is a latent squint that develops a corresponding disease value in connection with specific complaints and is classified according to the international diagnostic code (ICD) H50.5. A heterophoria can be associated with a so-called fixation disparity . This is a sensory peculiarity that shows a deviation of the facial lines from one another in the case of prism-induced loading of the fusional vergence and possibly represents an indicator of the insufficiency of bifoveal fixation . Is z. For example, in the case of an existing heterophoria, a deviation already exists without prism loading (rest disparity) and this disappears with the specification of prisms, one speaks of a facultative microanomaly . If this does not disappear after the prism is applied, one speaks of an obligatory fixation disparity . Basically it has been proven that people with an obligatory fixation disparity are not able to fuse precisely centrally. Prism treatments of a heterophoria with an obligatory fixation disparity can therefore usually not compensate this permanently.

On the basis of the required examination conditions, a distinction is made compared to associated heterophoria, which is why we are also talking about “dissociated heterophoria” here.

Compensating for an existing heterophoria by means of sensory and motor fusion can in some cases and for various reasons lead to complaints. These express themselves u. a. also in headaches, dizziness, double vision, burning eyes, blurred vision, neck stiffness, tiredness and poor concentration. This type of complaint is called asthenopia .

Diagnosis

It is assumed that only the anamnesis and complaint situation trigger appropriate activities and examinations.

  • Ametropia

The only method of discovering an ametropia and assessing its extent lies in the measurement and correction method according to Hans-Joachim Haase (MKH) - or in other words: an ametropia is only determined if this is carried out using the MKH procedure . The measurement is carried out using a binocular Polatest method with a constant degree of dissociation from Zeiss, in which the fusion is not completely eliminated (associative method). In particular, the offering of stereo images is part of the decisive examination process. The results, which show the quantitative strabismus deviation of the facial lines from each other and the extent of a "fixation disparity" as an image position error, are based on the patient's subjective information and are used to determine the prism strength to be adjusted. Differential diagnostic activities within the MKH procedure to determine possibly other disorders of binocular vision or also combination disorders - and thus to search for alternative causes of the complaints - are not known. There is no recognized standardization of the procedures used within the MKH.

  • Heterophoria

The examination of a heterophoria is standardized ( DIN 5340-209) and requires the complete interruption of the two-eyed vision (dissociating process). The latent squint angles are measured at different fixation distances with different methods and degrees of dissociation in free space ( e.g. masking test ) or by means of apparatus examinations ( haploscopes ). In addition, numerous examinations of the position of the eyes , eye mobility , the quality of binocular vision with regard to simultaneous vision, fusion (fusion width, fusion field of vision) and spatial vision (stereopsis), as well as the correspondence relationships between the two eyes are carried out for the differential diagnosis of the complaints . The results of the examinations are subject to subjective information from the patient and are also verified by a series of objective measures. Before the described complaints are causally associated with the corresponding findings, procedures for targeted exclusion diagnostics are among the examination measures. These include a so-called diagnostic Marlow bandage (the closure of an eye with a plaster over a period of approx. 3 days), as well as attempts to wear prisms, for example. In the first case it should be clarified whether the complaints can be traced back to disturbances of the binocular vision at all, in the second case it is determined whether a prism treatment can possibly represent a therapy possibility. If this is the case with a correspondingly high probability, it should be borne in mind that maximum deviations do not necessarily have to correspond to the subjective requirements of a prism correction.

The examination of a fixation disparity is usually carried out on haploscopic devices (e.g. phase difference haploscope ) using a Nonius arrangement. A fixation disparity will be detectable in almost every person above a certain load on the fusional vergence.

therapy

Example for prism glasses (due to their high thickness, accordingly thick)

A heterophoria with asthenopic complaints is a disease , as the angle defective vision with asthenopic complaints is not seen by its users , although this also represents an (associated) heterophoria. That is why the first case is referred to as therapy, the second as a correction. Basically, however, it is pointed out that in principle neither an associated nor a dissociated heterophoria necessarily has to lead to a prism correction.

  • Ametropia

According to their users, the only form of correction of the ametropia is the adjustment of prism lenses. The strength of the prisms is determined by the measurement results of the MKH and usually corresponds to the extent of the deviation of the visual axes from one another, although it is not clear whether this is the "image position error" or the squint angle of a heterophoria. Because of the lack of differentiating diagnostic measures, a reliable prognosis can usually not be made. If necessary, the prism strength usually has to be increased after some time, but not reduced. This can be repeated several times until, on the principle of trial and error, a situation arises in which it is clearly recognizable

  • that a prism correction neither eliminates nor alleviates the symptoms,
  • that a prism correction is now a satisfactory solution for the patient,
  • that a prism correction has so far reduced the asthenopia, but has to be intensified because of a again increasing complaint situation or
  • that a prism correction has so far reduced the complaints, but a necessary further increase in the prism strength is no longer possible due to optical and functional reasons.

In the latter case, an improvement can only be achieved if further care is passed on to the specialist group of strabologists, as the next step in treatment may be the implementation of a squint operation and the prism treatment in this case must be seen as an unintentional preparatory measure. The alternatives for those affected are to maintain the status quo or to discontinue the prism correction. In the best case, the latter will lead to a return to the original complaint situation. However, when the correction is discontinued, a continuous prism structure often leads to a decompensation of the heterophoria, an intensification of the complaints and thus to a significant worsening of the situation.

Until an acceptable prism strength has been found, a prism film can be applied self-adhesive to the spectacle lens and, in contrast to a ground lens, causes less costs, especially if its strength should change. However, the prismatic power is usually incorporated directly into the spectacle lens . These costs are incurred every time the prism values ​​are amplified. The health insurance companies do not assume the financial expenses incurred for this.

  • Heterophoria

If the diagnosis of heterophoria can definitely be linked to the symptoms expressed, various treatment concepts are possible which, depending on the type and extent of the squint, generally allow reliable prognoses.

On the one hand, so-called orthoptic exercise treatments can improve the situation. Depending on the type, these can be carried out by the patient himself at home, or he can go to a visual school attached to an ophthalmologist's practice for special equipment exercises.

Another possibility is also the adjustment and prescription of prism glasses, if the findings permit. This prescription is usually preceded by appropriate attempts at wearing it in order to be able to make an initial prognostic statement. Part of the treatment is also a thorough explanation of the risks and possible consequences of prism treatment. Here, too, it is possible that the strength of the prisms must increase over time, as is the case with the method of ametropia based on the principle of trial and error , possibly even up to a point at which the heterophoria decompensates so far that a prism correction is no longer possible. Until an acceptable prism strength is found, no prism glass is prescribed, but a prism foil . This can be applied to the spectacle lens in a self-adhesive manner and, in contrast to a ground lens, causes considerably less costs, especially if its thickness should change. Films have the disadvantage compared to glasses that they can be "visible" and thus cosmetically a little more noticeable. They also deliver a poorer quality image on the retina, the higher the prismatic power. Nevertheless, they are very suitable for a certain trial period and to support a prognosis. Prism foils are therefore always only interim solutions . The prismatic power is incorporated directly into the spectacle lens if the findings show reliable stability over a certain period of time. The need for frequent changes to prism values ​​is thus reduced as much as possible, although not completely excluded.

At the latest when it is first necessary to increase the prism strength, the discussion about a possible so-called prism structure will usually begin with the patient , a continuous increase in the prism strength with the aim of achieving the minimum squint angle required for freedom from symptoms and this then by means of a squint operation to be significantly reduced or eliminated.

A third variant consists in the direct planning and implementation of a squint operation, which is subject to strict indications and is generally only carried out in the case of heterophoria of greater extent, which has been reliably identified as the cause of the symptoms. A squint operation is only carried out if all other treatment measures have remained unsuccessful or if these would certainly not lead to a satisfactory result.

Summary

Despite the different terminology , it is now agreed that one and the same clinical picture is described with ametropia and heterophoria . The only difference is in the method of investigation of the associated and dissociated heterophoria, the results of which, however, have been proven to show no significant differences. With the use of prism corrections, there are also points of contact in the therapeutic approach between evidence-based medicine and the advocates of ametropia and MKH. However, the limits of the similarities have already been reached. A concept that goes beyond the known and scientifically validated procedures is superfluous, since strabology already covers all the necessary examination and treatment principles in a high-quality and differentiated manner, and the MKH, in particular its therapeutic approach, has nothing new to offer that is actually not already the daily one Represents practice in ophthalmology. Their use as a diagnostic procedure and pure examination method does not necessarily have to exclude this.

A critical consideration requires the fact that in connection with a certain symptom, the "dissociated heterophoria" is classified as a disease, while the proponents of the angular ametropia known as "associated heterophoria" only give the status of a "visual defect". For this it must be noted:

  • By law, illnesses can only be treated by certain professional groups. Opticians are not included and are not allowed to offer any treatment.
  • In the case of the ametropia, there is neither a disease nor a treatment, but a "visual defect" and a "correction".

The different quality of the concepts becomes clear in the comparison. The number of those who work with the term ametropia and use the MKH is very small. This procedure has not yet caught on with opticians or strabologists, quite apart from the unsatisfactory and inadequate scientific validation of the overall concept.

In the discussion that has been conducted, the question is in principle not whether prism treatment can be useful or not for the symptoms, complaints and findings described. This question has long been adequately answered by scientists, opticians and strabologists, regardless of which diagnosis this measure is based on. It remains to be clarified who may initiate such a treatment and when and with what means it is to be carried out. It has been proven and generally undisputed that the technical core competence for this lies in the strabological professional profile of orthoptists . Even the legal disputes and judgments have so far not been able to bring about a very reliable and binding status in this matter. In particular, the problem of the lack of objective comparability, which is caused by the accepted use of the terminology “correction of a visual defect” versus “treatment of a disease”, prevents a concrete solution.

Regardless of this, there are a number of those affected and patients who are ready to accept the “diagnosis” of hamstring and the appropriate treatment, not least because they have found a person in the attending optician or ophthalmologist who can deal with their complaints and May address problems more intensely than may have been previously done by specialist colleagues. The field of strabology is a specialty ophthalmological discipline that still seems underrepresented in comparison to the actual need even after decades. A corresponding strabological offer, which critically accompanies the subject of ametropia and offers the affected person not only competent information but also quality-assured treatment, is provided by highly trained specialists, but has obviously not yet been established across the board.

Legal assessment

  • The Administrative Court of Baden-Württemberg makes a legal and legally binding assessment and confirmed the following in the second instance in a judgment of February 17, 2005 - quote: “An optician may only sell prismatic glasses on the basis of a doctor's prescription or after a written and verbal advice that he I do not want to and cannot carry out any medicinal treatment and therefore, as a precaution, leave the consultation of a doctor or alternative practitioner with the appropriate permission at the disposal. […] The VGH has […] confirmed that the delivery of prismatic lenses without the […] required notice is an exercise of medicine that requires a permit under the Heilpraktikergesetz and is therefore a criminal offense. ” An appeal against this judgment was not permitted.

See also

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literature

  1. ↑ a b Press release of the Professional Association of Ophthalmologists Germany e. V. (BVA) on the measurement and correction methodology according to HJ Haase ( Memento of the original from September 27, 2007 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.augeninfo.de
  2. ↑ [1] Dictionary of Optometry , Dr. Goersch, source: Dr. med. Fritz Gorzny, publications DOZ-Verlag
  3. ↑ Members of IACDS
  4. ↑ PLOS.org
  5. ↑ Study to clarify needs on the subject of orthoptics, 2007 (PDF; 723 kB)
  6. ↑ Press release of the Administrative Court of Baden-Württemberg of March 2, 2005: Treatment of ametropia by opticians is only allowed with conditions

Scientific links

  • Miriam Kromeier, Christina Schmitt, Michael Bach , Guntram Kommerell: Do prisms according to Hans-Joachim Haase influence the prevalence of eyes? In: Clinical monthly sheets for ophthalmology. 219, 2002, pp. 851-857, doi : 10.1055 / s-2002-36951 .
  • V. Schroth, W. Jaschinski: Associated heterophoria and front-back asymmetry of the prevalence of an eye. In: Clinical monthly sheets for ophthalmology. 223, 2006, pp. 233-242, doi : 10.1055 / s-2005-858852 . (Clinical study on the front-rear asymmetry of the prevalence, in which aspects are deepened that were not considered at the University Eye Clinic Freiburg and which partially support the hypotheses of H.-J. Haase - but only from a purely statistical point of view)

Legal links

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