Comparative Studies of the Effects of Dfamox and Neptazane on the Intra-Ocular Pressure

The purpose of this paper is to collect the comparative data regarding the actions of Diamox and Neptazane in short-term and long-term administrations. This investigations were divided into three parts. (1) a single dose response in normal and glaucomatous eyes, (2) actions on aqueous flow and (3) long-term treatments in glaucomatous eyes. (I) A single dose response. Ten eyes from 10 normal subjects, ages ranging from 24 to 57 years, were chosen. They were given 500mg of Diamox or 100mg of Neptazane alternately and intra-ocular pressure was determined at regular intervals. In another series, 18 eyes from 18 glaucomatous patients were investigated in the same manner. The patients comprise 13 cases of chronic simple glaucoma and 5 cases of chronic narrow-angle glaucoma. No considerations were given as to their sex and age differences. Prior to administration of the drugs, the diurnal variations of intraocular pressure in each eye had been recorded during the daytime. The intra-ocular pressure was measured by Goldmann's applanation tonometer. (II) Actions on aqueous flow. Actions of Diamox (500mg) and Neptazane (100)mg on the aqueous flow were studied by the perilimbal suction cup method of Rosengren and Ericson in 8 normal eyes. The suction cup was applied 3 hours after Diamox and 6 hours after Neptazane administration. (III) Long-term treatments. Fifteen glaucomatous patients, 10 chronic simple glaucoma and 5 chronic narrow-angle glaucoma, were investigated. Their ages were from 43 to 61 years. The schedules of dosage were 250mg of Diamox, t.i.d. or 50mg of Neptazane, t.i.d. and followed up to 35 days. In some cases, treatment was discontinued or the doses were reduced to 250mg of Diamox, b.i.d. and 50mg of Neptazane, b.i.d., due to the side reactions. Results: (I) Results of measurements of intra-ocular pressure in normal eyes were shown in Table 1 and 2. (a) Diamox: The ocular tension begins to fall as early as 30 minutes, and maximal lowering occurred between 1~4 hours (average, 2.3 hours). Thereafter, tensions rose again and returned to the original level within 24 hours in all cases except in 2 cases. The maximal reduction was on the average 3.7mmHg. Side reactions were observed in 3 cases. (b) Neptazane: The tention begins to fall 0.5~1 hour and the maximal fan was obsered between 4~8 hours (average, 6.4 hours). The maximal degree of fall was 3.3 mmHg. The ocular pressure was still low after 24 hours in all cases except in 3 cases. No side reaction was encountered. (B) In glaucomatous eyes: Results were summarized in Table 3 and 4. (a) Diamox: Ocular tension begins to fall: 30 minutes and maximal fall was attained at 2.2 hours. The degree of maximal reduction was 13.7 mmHg. The lowered tension returned to the initial level within 24 hours in most cases. Side reactions were observed in 5 cases. (b) Neptazane: Ocular tension begins to fall 0.5~1 hour and maximum lowering was observed after 6 hours. The extent of maximal fall was 12.3 mmHg. The ocular tension was still low after 24 hours in most cases Side reactions were encountered in 3 cases. (II) Perilimbal suction cup studies revealed that both Diamox and Neptazane reduced the aqueous flow considerably as shown in table 5. (III) Results of long-term treatments were tabulated in table 6 and 7. (a) Diamox: The maximal degreess of fall in ocular tension were observed relatively early in the treatment and thereafter the tension fluctuates irregularly and showed tendencies to gradual rises. Sid effects were observed in 10 cases. Complete normalization of ocular tension, e.g., under 21 mmHg, was achieved in 8 cases. (b) Neptazane: The same tendency was observed in this group. Side reactions were encountered in 6 cases and milder than in Diamox treated group. As these results show, both Diamox and Neptazane showed a significant tension lowering effect. Neptazane is five times more powerful than Diamox in equal dosage basis. The ocular pressure falls more slowly and its duration was longer in Neptazane treated eyes. Sid reactions were observed more frequently in Diamox group and somewhat severe.

Changes in the Viscosity of Rabbit's Vitreous Humor Induced by Infusion of Urea

The viscosity of rabbit's vitreous filtrate was measured after intra-venous infusion of 30% urea in 10% glcuose solution and 10% glucose solution. The dosage administered was 1g per kg of body weight. As shown in table, the relative viscosity increased after infusion of urea and glucose solution and no difference was found in the extent of increase in viscosity between urea- and glucose-treated groups. The mechanism of viscosity increase and its relation to the intra-ocular pressure were discussed.

The Significance of the Glucose Content of the Retina in the Alteration of the B-Potential Induced by Retinal Ischemia

The experiments were performed on albino rabbits in which retinal ischemia had been produced by elevating tbe intraocular pressure to 120 mmHg by canulation of the anterior chamber and serial electroretinograms were recorded. The animals were divided into 3 groups; the first served as a normal control,the second received 30cc of 50% glucose solution intravenously, and the third received 2 units of insulin intramuscularly. The light stimuli used was 200 lux at the animal's eye and its duration was O.1 second. The contents of glucose and glycogen together were shown in table 1 and figure 1. The content was the greatest iri group II and the least in group III. After elevation of the intraocular pressure, b-wave gradually decreased and finally extinguished. The disappearance time of the b-wave in 3 groups of animals was shown in table 3 and figure 3. The survival time of the b-wave was longest in group II and shortest in group III. After 15 minutes of retinal ischemia, the intraocular pressure was returned to 15mmHg and the retinal blood flow was restored. The b-wave reappeared and the time at which b-wave recovers 50% of the original amplitude was shown in table 4 and figure 4. The b-wave recovers the quickest in group 2 animals and latest in group 3. In conclusion, when the glucose content of the retina is high, the resistance of the b-wave against the retinal ischemia is high and its recovery after restoration of the blood flow is quick. The significance of the glucose content of the retina and its role in retinal metabolism were discussed.

Clinical Applications of Goldmann Applanation Tonometer

The basic principles of the applanation tonometer and Schiotz tonometer were briefly discribed. The major improvement in the applanation tonometry is in the fact that the scleral rigidity plays no important role in the determination of the intra-ocular pressure. We have measured the intra-ocular pressure with both types of tonometer, the applanation tonometry being the first, followed by Schiotz reading with 5.5 g weight. In normal eyes, both readings gave almost identical results. In glaucomatous eyes, recently operated cataract eyes and eyes with retinal detachment successfully operated showed wide discrepancies between the values of two methods. The pressure readings with Schiotz tonometer were moderately lower than that with applanation tonometer, and this might cause erroneous conclusion regarding the real status of the intra-ocular pressure in such eyes. Advantages and disadvantages of the applanation tonometery were discussed.