Satoshi Ishikawa

A QUASI‐STATIC STUDY OF ACCOMMODATION IN AMBLYOPIA*

Abstract— A method named quasi‐static recording of accommodation is introduced. While accommodative stimulus (AS) is slowly changed over a wide range with a constant velocity (0.2 D s‐1), accommodative response (AR) is continuously measured. AS and AR, respectively, are recorded on the abscissa and the ordinate of an x ‐ y recorder to produce a “quasi‐static” response/stimulus curve.

Accommodative adaptation and age of onset of myopia

Tonic accommodation in an empty field and accommodative adaptation, defined as accommodation shift after 2 min viewing of a 4 D near task, were measured using an infrared optometer. Subjects were classified into three types: emmetropes (n= 18). early onset myopes (n= 18) and late onset myopes (n= 15). The relationship between accommodative adaptation and the onset age of myopia were compared. There was no statistical difference in the pre‐task ionic accommodation among the three subject groups. However, the accommodative adaptation differed in the three groups during the 5 min post‐task period. The average accommodative adaptation of emmetropia. early onset myopia and late onset myopia were 0.66. 0.27 and 1.19 D. respectively. Accommodative adaptation in the late onset myopia group was significantly higher than in the emmetropia group. Furthermore, the accommodative adaptation in the early onset myopia group was significantly lower than in the emmetropia group. Two possible aetiologies of myopia are discussed: one for the group which shows low accommodative adaptation that has no relationship with the age of onset and another for the group which shows high accommodative adaptation that has a relationship to an onset age of 15 years or later. The aetiology is also considered with regard to a potentiating chemical effect on the synapses of the ciliary muscle.

Ultrastructure of Iris Muscles in Diabetes mellitus

Fine structure of iris muscles from 16 iris specimens in patients with diabetes mellitus were investigated by electron microscopy, and the results were compared with those of 10 specimens of senile cataract eye without diabetes of the corresponding age groups. Significant ultrastructural changes were extensively found at the regions of the dilator, sphincter muscles and of the nerves endings adjacent to them. To cytoplasm of the muscle cells was partly occupied by membraneous structures with concentric lamellar appearance. Cytoplasmic vacuolations were noted in the muscle cells. An increased number of the lipid droplets associated with pigment granules in the cells was found in all diabetic iris specimens. These three kinds of pathological changes (lamellar structure, vacuole, and lipid droplet) increased depending on the duration as well as the control of the disease. Althought these findings were noted both in the sphincter and dilator muscles, the latter seemed to be more severely affected. Degenerative nerve endings containing lamellar membraneous structures were observed in a few moderate cases. Nerve fibers frequently diminished in diabetic patients, especially in severe cases with longer duration together with poorly controlled cases. These findings suggest that diabetes involves the iris muscle cells as well as the nerves, and these changes might be a reason to produce a pupillary abnormality.

A quasistatic study of pupil and accommodation after-effects following near vision.

The study examines the effect of a near task on immediate post‐task measures of pupil size and accommodative state. The method of quasistatic measurement of accommodation was used and pupillary changes elicited by the accommodative stimulus were simultaneously recorded using an infrared video‐pupillometer. This method requires a short (typically 2 minutes) but strong (up to 10 D in most subjects) near‐vision effort, with the accommodative and pupillary responses being recorded before, during, and after the task. The results show pupil after‐effects to be more pronounced than tonic accommodative after‐effects. Inter‐individual difference in after‐effects is large. The pupil after‐effect was dissociated from the tonic accommodation after‐effect and lasted in some cases for more than 15 minutes. The pupil after‐effect was not masked by darkness. It is proposed that monitoring the changes of pupil is valuable when assessing the after‐effects of sustained near vision.

Edge-light pupil oscillation of optic neuritis

Edge-light pupil oscillations induced by a thin slit of light projected from a streak retinoscope and focused on the pupillary margin were recorded by an infrared television pupillometer. The oscillation period expressed as pupil cycle time (PCT) was calculated by hand from the recorded chart and by means of a digital computer with an analogue to digital converter in selected cases. In these cases, Fourier analysis was also undertaken.Forty patients with optic neuritis and 60 normal subjects, matched for age. were examined. The mean value and standard deviation of the PCT obtained by hand analysis of the pupil oscillation were 851±70 msec in the affected eyes of patients with optic neuritis and 834±65 msec among the controls. By computer analysis. the PCT in the affected eyes of patients with optic neuritis was 892±89 msec, while the value obtained for the controls was 890±64 msec. There were no statistical differences between patients and controls in either method. However, in patients with optic neuriti...

Accommodative fluctuations in Adie's syndrome

Recent reports suggest that the higher frequency components (around 2 Hz) of accommodative fluctuations may arise from the accommodative ‘plant’ and may have no role in the control of the accommodation system. The dynamic responses of accommodation in two cases with Adies syndrome were recorded. The results showed that the velocity of accommodative responses was reduced, and the accommodative fluctuations in the higher frequency components were completely diminished. It can be concluded that the origin of fast fluctuations is not located at a more peripheral site than the lesion of tonic accommodation. Since the possible lesion exists at the ciliary ganglion, the origin of the fast oscillation may not be the accommodative ‘plant’, but the neural one.

Adrenoceptors Affect Accommodation by Modulating Cholinergic Activity

In an attempt to clarify the functional role of adrenoceptors in accommodation, the effects of various adrenergic agents on the state of accommodation were studied. Fifty-two emmetropic, visually normal subjects (24.6 +/- 0.42 years old) participated in this study. Using an infrared optometer, the far and near points of accommodation were measured by a quasistatic method. Tonic accommodation and accommodative adaptation were also investigated. All these parameters were measured before and after topical application of various adrenergic agents. Both bunazosin hydrochloride (0.1%) and phenylephrine hydrochloride (5%) had no effect on tonic accommodation and accommodative adaptation. However, bunazosin hydrochloride increased the near point of accommodation. Timolol maleate (0.5%) and isoproterenol hydrochloride (3.0%) did not affect tonic accommodation. Isoproterenol hydrochloride evoked a hyperopic shift of the far point of accommodation by 0.23 +/- 0.42 diopters (D). Additionally, accommodative adaptation was increased by timolol maleate (0.36 +/- 0.62 D) and decreased by isoproterenol hydrochloride (0.18 +/- 0.48 D). These results indicate that both alpha and beta adrenoceptors affect accommodation. Activation of alpha adrenoceptors increased the near point of accommodation and activation of beta adrenoceptors decreased accommodative adaptation, which suggests that activation of adrenoceptors may modify parasympathetic activity; hence, affecting the state of accommodation.

Ultrastructural hepatic changes by carbamate pesticide (Sevin) in rats.

Abstract Carbamate pesticide (1-naphthyl- N -methyl carbamate, Sevin) was administered orally to adult male rats with an average body weight of 200 g on a short-term (a single 30-mg dose per rat) as well as a long-term (fifty 3-mg doses per rat over a 1-year period) basis. The feeding schedule was strictly controlled by allowing 3 hr of feeding followed by 21 hr of fasting. The short-term group was sacrificed 20 and 44 hr after the administration of Sevin and the long-term group was sacrificed 60 days after the termination of the treatment. At the time of sacrifice, biochemical measurements of blood glucose and serum immunoreactive insulin were made. The findings were compared with those from a group of untreated control animals. Blood glucose was reduced at 20 hr and elevated at 44 hr, whereas immunoreactive insulin was elevated, particularly at 44 hr. The agranular endoplasmic reticulum increased at 44 hr. Swollen mitochondria were seen at both times but were more obvious at 44 hr. In the long-term group, blood glucose was elevated and immunoreactive insulin was slightly reduced. Glycogen disappeared in most of the hepatocytes. The cells contained predominantly dilated granular endoplasmic reticulum with swollen mitochondria. These data indicate that Sevin administered orally over both the long and short term appears to involve the hepatic glycogen metabolism.

Pupil Constriction Latency in Optic Neuritis

Using binocular infrared pupillometer (C-2515, Hamamatsu Photonics), 12 patients (14 eyes) of optic neuritis were examined in both acute and recovery stages. Pupil constriction latency (CL) was prolonged in acute stage as compared with normal fellow eyes (p＜0.001). In recovery stage, constriction latency improved significantly (p＜0.05). Constriction velocity (CV) was decreased in acute stage as compared with normal fellow eye (p＜0.05), however it did not seem to improve in recovery sage (p=0.721). As for dilatation velocity (DV), in both acute and recovery stages, there were no significant differences between affected eyes and normal fellow eyes By theoretical deduction, the constriction latency prolongation can be shown to be due to afferent route rather than efferent route. The CL prolongation in acute stage can be explained by optic nerve demyelination, as generally agreed. Like other visual functions it improved during recovery to a near normal level. The CV was impaired in both acute and recovery stages, and there seemed to be no improvement. The DV was normal in both acute and recovery stage, which we consider to be the effect of a constant sympathetic stimulation. The afferent and efferent routes are differentiated by deduction-which is not possible by traditional pupil examination methods such as pupil cycle time or relative afferent pupillary defects.