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Monocular and binocular reading curves of 20 patients (4 with cataract, 5 with glaucoma, 11 with maculopathy) were recorded by infrared oculography. Reading speed was found to be directly proportional to the visual acuity of the eye tested. However, the same visual acuity in both eyes does not always mean that the subject reads at the same speed with both eyes. For example, paracentral visual field defects impair reading ability and eyes which appear to have good vision may easily become tired. Twelve of 16 examined eyes with maculopathy showed a significant decrease in reading speed during a reading test lasting no more than 2 minutes. In tests of the same duration cataract patients did not tire; their reading speed increased. Binocular vision helps improve reading speed in cases of maculopathy, and even more so in cases of glaucoma with visual field defects. Attention is drawn to Mackensen's suggestion that measurement of reading speed is a valuable function test, and to the fact that in certain cases fatigue of an eye during reading is a new and measurable criterion of the degree of visual impairment.

Since it is well known that the eye musculature undergoes degenerative alterations in old age, the question arises whether squint operations are effective in presbyopic and elderly persons. Twenty-four patients with horizontal squint (average age 63 years) wanted the operation because of diplopia, asthenopia and, in a few cases, for cosmetic reasons; 5 patients were aphakic. The operation was successful in 20 cases. The principles of dosing the operation are essentially the same as for juvenile patients. However, specific difficulties in treating elderly patients arise from: (1) lack of accommodative convergence, as a result of which the squint angle difference between distance and near fixation is usually greater; (2) increasing rigidity of the eye muscles, which diminishes the range of fusion; as a result, the patient is unable spontaneously to compensate for minor squint deviations; (3) senile organic lesions of the bulbs further impair fusion. It is advisable to treat convergent squint by correcting the average deviation between distance and near fixation, preferably shortening the external recti. Cases of divergent squint should preferably be treated by correcting the smaller squint angle, with resection of the external recti. The older the patient is and the worse his fusion, the more precisely the operation has to be dosed. Orthoptic training helps in old patients too.

Zusammenfassung. Unter Horror fusionis versteht man standige, in kleinster Distanz oszillierende, nicht korrigierbare Doppelbilder. Die Pathophysiologie war bislang unklar, die Ursachen des Fusionsverlusts uneinheitlich. In der Annahme, es handle sich um einen Defekt im Steuerungssystem der Mikromotilitat, wurden an drei Patientengruppen die Interfixationsbewegungen binokular simultan mittels hoch auflosender Infrarot-Reflexions-Okulographie (IROG) registriert: 1. Diplopie nach Operation einer lange bestehenden Cataract oder Aphakie (n = 26), 2. nach schweren Schadel-Hirntraumen (n = 12), 3. bei Strabismus (n = 2). In jedem Fall and korrelierend mit der Schwere des Zustandsbildes waren die Fixationskurven pathologisch: Gruppe 1 zeigte sinusahnliche Pendelbewegungen vor allem des deprivierten Auges horizontal oder vertikal bis zu 5 0 Amplitude bei sehr langsamer Frequenz von 0,3° Hz; Gruppe 2 bot irregulare rasche Schwankungen bis 3° Amplitude; reichlich square-wavejerks, Schielwinkelschwankungen vor allem in die Divergenz; auffallend war die rasche Ermudbarkeit der Okulomotorik nach Schadel-Hirntraumen.Die Studien zeigen die Moglichkeit auf, subjektive Beschwerden mittels IROG objektiv zu bestatigen. Dies ware oft fur Fragen der Unfall-Begutachtung and der Arbeitsfahigkeit von entscheidender Bedeutung.Schlusselworter: Diplopie unkorrigierbar, visuelle Deprivation Erwachsener, Interfixationsbewegungen, Infrarot-Reflexions-Okulographie, Schadel-Hirn-Traumen. Central Fusion Disruption. A Disorder of Sensomotoric FunctionsSummary. Central fusion disruption means permanent in small distance oscillating diplopia, not correctable by prisms. The pathophysiology of this condition -caused by loss of fusion -is unclear. Supposing to be a defect in the control system of micromotility, three groups of patients suffering from diplopia underwent the recording of their binocular interfixational movements at our device of Infrared-Reflection-Okulography (IROG) with high resolution: 1. operated long-standing cataract or aphakia (n = 26), 2. severe craniocerebral trauma (n = 12), 3. strabismic patients (n = 2). No case showed normal interfixational movements. Group 1 had slow sinusoidal waves of the deprived eye up to 5° amplitude, frequency 0,3 Hz. * Diese Arbeit ist dem Gedenken meines Lehrers F. A. Hamburger gewidmet. Sie ist zum Groflteil an der I. Univ.-Augenklinik in Wien entstanden.Group 2 showed irregular uncoordinated instability of excursions up to 3° amplitude, numerous square-wave jerks, changes of the binocular eye position into divergence and early fatigue of the motor eye functions. Thus by means of IROG we are able to verify subjective complaints of double vision. This seems to be important in questions of law and fitness for work.

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