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It is accurate to date the first scientific report about colour-deficiencies on 1777. Earlier descriptions may be followed up to the end of the 17th century. But usually it is only mentioned, that mistakes had happened. Huddart 1777, however, reported for the first time, that more than one person was involved in a family and that demonstrations of coloured ribbons helped to find out which colours became confounded. The famous self-observation of Dalton contains the assortment of individually combined silk-threads, which is an anticipation of subsequent arrangement-tests. Goethe developed a systematic arrangement-test of self-made small coloured targets with colours out of his own colour-wheel. A. Seebeck was the first who--using the spectrum for examination--found out that a special group of subjects showed a shortening of the spectrum at the red end. From this result Helmholtz concluded the existence of two types of red-green blindness. This new argument for the trichromatic organisation of our colourvision was the basis for the statement of the three types: protanopia, deuteranopia and tritanopia (v. Kries, A. König). Rayleigh later on succeeded in finding out anomalous trichromats following preparatory examinations of Maxwell. Nagel has the merit to have analysed protanomaly and deuteranomaly using the anomaloscope constructed by himself. Side by side with the spectral colour-tests pseudoisochromatic plates were developed for diagnostic purposes, at first thought out and introduced by Stilling and in the meantime used in many variations.

It has been known since the time of Koellner that some diseases of the retina produce a shift of the Rayleigh equation toward red on the anomaloscope. In 1951, at the suggestion of Engelking, this "pseudoprotanomaly" was analyzed using Helmholtz's color mixer at Heidelberg University Eye Clinic. Pseudoprotanomaly is pathognomonic for diseases accompanied by macular edema (central serous chorioretinitis) as well as for the early stage of Stargardt's macular degeneration. The various hypotheses regarding its origin are discussed. In cases of visual disturbance with just-recognizable scotoma, ophthalmoscopy does not permit a definite differential diagnosis between retrobulbar neuritis and a macular lesion. In these cases "pseudoprotanomaly" is a definite sign that there is a macular lesion and not a retrobulbar neuritis.

Impression cytology specimens of the conjunctiva can be examined by scanning electron microscopy. If a cellulose-acetate filter is pressed onto the conjunctiva, the microvilli-bearing epithelium becomes so firmly attached to the fine meshwork of the filter that the most superficial conjunctival cell layers adhere to the filter. When the filter is removed intercellular connections are destroyed without any damage to the cell membranes being detectable in the SEM image. Since the surface of the corneal epithelium is spread out on the filter and is firmly attached to it the lateral bond between the cells is preserved. Shrinkage is minimal. The posterior surface of the epithelial cells, facing the observer, consists of smooth, porous cell membranes. The nuclei of many cells are clearly distinguishable. Since it can be directly compared with light-microscopic specimens, the SEM image can help provide answers to morphological and pathological questions, and may represent a useful diagnostic aid.

Magnifying spectacles represent one of the indispensable optical aids (Keplerian systems having surpassed Galilean systems during the last years), closed-circuit television, Optacon, and navigating aids based on ultrasound as environmental sensors. -None of the other navigating aids have proved useful. Initial successes have, however, been achieved with a miniature hand-held camera for closed-circuit television and a portable electronic reading system (View-Scan). Genuine progress has been made with the braille information storage systems, which utilize computer technology to store texts which have been read and written, and subsequently to print them or reproduce them on a screen or in synthetic language. Braillex in the Federal Republic of Germany and Versabraille in the U.S.A. are examples of such systems. In special cases a newly developed stereo photocopy system (Minolta) will be useful for newly blinded adults. However, texts in the form of tactile copies have to be highly magnified in order to be palpable and readable.

This report deals with electronic reading aids enabling patients with a visual acuity of less than 1/50 to read black-and-white-printed matter. A survey on experience with the Optacon from 1971 on is furnished and the chances of vocational training and the use of supplementary aids. The very handy Optacon (weight: 2 kg) consists of a miniature opto-electronic camera, and a tactile stimulator area consisting of 144 tiny metal rods. The development of another very useful instrument in the hands of the blind looks toward completion: The Braille-Converter. Its functions in short: A TV camera with an intermediate computer which transfers optical information into braille or spoken language.

Impression cytology is a non-invasive, repeatable, and uncomplicated method of examining the conjunctiva. Cellulose-acetate filters are used to remove the superficial layers of the conjunctiva. This technique causes no subjective discomfort to the patient. The method combines the advantages of a biopsy with those of a "Häutchenpräparat." The authors used 3 different stains for the conjunctival imprints: PAS-hematoxylin, Alcian blue and a combination of Alcian blue and PAS. From the different staining characteristics of the goblet cells it was possible to draw conclusions about different functional cell conditions. The metachromatic properties of a few cells among the large number of epithelial cells led to speculation on the existence of different cell types and their possible correlation with the various cell types described by Rohen for the conjunctiva of monkeys. In patients with keratoconjunctivitis sicca or Sjögren's syndrome pathologic nuclear changes occur that lead to chromatin taking on a snake-like appearance, the so-called "snakes." To the authors' surprise, similar chromatin changes were found in a great number of cells of contact lens wearers, with frequency depending on the type of contact lens. Impression cytology is a special method of non-invasive biopsy providing new possibilities for diagnosis, differential diagnosis, and therapeutic control of conjunctival disorders.

With tonometric and tonographic measurements it is possible to detect and record oscillations which are synchronous with the intraocular pulse. These oscillations decrease with increasing IOP. In contrast, with direct manometric measurement, the amplitude of the intraocular pulse increases with increasing intraocular pressure. Therefore, in order to determine the intraocular pulse amplitude in patients, direct manometric measurements were performed on blind or almost blind eyes. Intraocular pressure was experimentally elevated by injecting fluid through a cannula into the anterior chamber, using a special Guyon syringe. The course of the drop in pressure and the amplitudes of the intraocular pulse were recorded with the Neuhaus apparatus and a light-spot pen. The most striking result was that in neovascular glaucomas there are excessive pulse amplitudes. The question whether the poor prognosis of neovascular glaucoma is associated with these intraocular pulsations is discussed.

In the normal population a physiologic arcus senilis develops in the 6th and the following decades. Hyperlipoproteinemia (type II a and type II b) however may be the cause of an earlier onset of a corneal arcus. 63 patients with hyperlipoproteinemia type II a and type II b were examined with slit-lamp. In more than 75% of these patients corneal arcus were found already in the 5th decade. Normal population of the same age in contrast shows an arcus corneae only in 25%. Prospective examinations of the Western Collaborative Group found out, that men, 39-49 years old, had with corneal arcus a significantly higher incidence of coronary heart disease, compared with those without arcus. The average annual incidence of symptomatic myocardial infarction was 6.8 per 1000 with arcus as compared to 3.2 per 1000 without. In the 6th decade however there was no more any difference between subjects with arcus and those without arcus. These results, together with the findings of our study, show that one ought to examine the blood-lipids, if by chance of the first refraction a fully developed arcus corneae is found.

Cases of keratoconjunctivitis sicca with keratitis filiformis (with and without Sjögren's syndrome) with severe courses cannot be treated adequately with artificial tears. Only since the discovery of Eledoisin, which was introduced for ophthalmological therapy by Bietti, has a drug been available which directly stimulates tear secretion. Eledoisin was discovered in the salivary glands of certain Mediterranean species of octopus and can meanwhile be produced synthetically. A randomized study conducted at the University clinics in Heidelberg, Cologne, and Ulm showed that Eledoisin is significantly superior if the statistics are based on cases with severe courses. Cases with less severe courses also respond well to therapy with artificial tears.

Acquired colour-vision deficiencies are an early indicator for drug-induced retinopathy as well as drug-induced retrobulbar neuritis. Koellner's rule, which says, that damage of the retina induces a tritan-defect, and damage of the optic nerve induce a red-green-defect is also valid for defects secondary to drug-toxicity. Pseudoisochromatic plates, anomaloscope and other tests (Panel D-15-test) have to be selected correspondingly to use them as screening-methods.

Nutritional Tyrosinemia in animal experiments (Schweizer, Burns a. o.) caused an epithelial corneal dystrophy. The corresponding clinical picture is the Richner-Hanhart-Syndrome with herpetiform epithelial corneal dystrophy, palmo-plantar-keratosis and -- in some case -- a later developing oligophrenia. Goldsmith and coworkers suceeded to find out that all these symptoms are combined with tyrosinemia presumably caused ty one congenital enzyme defect. -- Personal clinical observations of such patients demonstrate that as well the corneal as the dermatological symptoms could be cured by diet, if the diagnosis is made in childhood. Corneal symptoms are still absent with a tyrosinemia as high as 10 mg%. Dietetic formula was found out to maintain this level, which is low enough to avoid the symptoms of Richner-Hanhart-Syndrome and certainly high enough to avoid symptoms of nutritional deficiency. One might expect that oligophrenia will not develop if this diet is used consequently. -- Since the first corneal symptoms develop already during the first years of life the ophthalmologist ought to know this etiology. The levels of tyrosinemia are so exorbitant (30--50 mg%) that the laboratory diagnosis is possible without any difficulty. If the diagnosis is only made in adult patients dietetic therapy is of limited value.