Berit Calissendorff

Cyclic variations in the c-wave amplitude of the sheep ERG☆

Abstract The c -wave of the sheep electroretinogram was studied in long-term experiments. It was found that the c -wave amplitude changed as a function of time and these alterations were dependent on frequency of the stimulus flash used. A slow oscillation (frequency about 0.3–0.5 per hr) of the c -wave amplitude was observed, using 1 sec light stimuli and long flash intervals (2 min). Shorter flash intervals gave rise to oscillations with a frequency of about 2 per hour. These fast oscillations initially were of relatively large amplitudes but decreased with time and reached a constant level after about 100 min. Shortening of stimulus duration (0.1 sec) resulted in c -waves of less amplitudes, but the cyclic variation pattern described above did not change.

SELECTIVE EFFECT OF A NEW ANTITUBERCULOUS DRUG, RIFAMPICIN, ON THE c-WAVE OF THE SHEEP ELECTRORETINOGRAM

Quite recently it was found that i.v. injections of 14C-labelled rifampicin gave rise to marked radioactivity in the w e a l tract (and presumably in the pigment epithelium) of the pigmented mouse (Boman 1973). This finding contrasted to the faint radioactivity obtained in the albino mouse. The difference in distribution pattern of 14C-labelled rifampicin between pigmented and albino mice was interpreted as being due to an affinity to melanin in the uvea and the pigment epithelial cells of the pigmented mouse retina. Recently an ERG method was developed which allowed studies of the slow components of the sheep ERG (Knave, M ~ l l e r & Persson 1972). One of these slow components in the c-wave, which is known to reflect the activity of the pigment epithelial cells in vertebrate retinas (Noel1 1953, Brown & Wiesel

Ophthalmopathy and hyperthyroidism. A comparison between patients receiving different antithyroid treatments.

Abstract The ocular manifestations in 125 thyrotoxic patients observed for 6–20 years are presented. The incidence and development of ophthalmopathy in three different treatment group medical‐ (η = 72), radionuclear (η = 36) and surgical (η = 17) are showed. The degree of ophthalmopathy is similar in all groups, and no statistically significant difference is found in the development of ophthalmopathy.

ADDITIVE INTRAOCULAR PRESSURE REDUCING EFFECT OF TOPICAL TIMOLOL DURING SYSTEMIC β-BLOCKADE

The effect on intraocular pressure (IOP) of topical timolol was studied in 30 patients with arterial hypertension treated with oral alprenolol, metoprolol or timolol. No patient had any known eye disorder. Topical administration of timolol induced a significant reduction of IOP regardless if the patients had systemic β‐blockade or not. Treatment with topical timolol alone was equally effective in reducing IOP as combined topical and oral therapy. Patient compliance was checked with plasma concentrations of the different β‐blockers.

Intraocular pressure after extracapsular cataract extraction with implantation of posterior chamber lenses

ABSTRACT To determine factors which influence postoperative intraocular pressure (IOP) we retrospectively reviewed changes in pressure during the first postoperative week in 633 consecutive eyes undergoing extracapsular cataract extraction (ECCE) with implantation of a posterior chamber lens The material was restricted to four surgeons and two types of lenses IOP was measured preoperatively, one day and one week after surgery Glaucomatous eyes (n=113) as well as exfoliative non‐glaucomatous eyes (n=79) had a higher mean IOP (278 and 261 mmHg) the first postoperative day compared to ‘simple’ cataract eyes (201 mmHg) After one week mean IOP in glaucomatous eyes still remained elevated while exfoliative non‐glaucomatous eyes had regained preoperative values Mean IOP on the first postoperative day (188, 245, 231 and 132 mmHg respectively) was also dependent on surgeon To some extent the IOP could be correlated to tightness of suturing as estimated by keratometry Only one surgeon had significant difference between irrigated and non‐irrigated visco‐elastic substance Postoperative pressure was not only dependent on the status of the patient̂s eye, but factors for the individual surgeons seemed to be as important

Melanotropic drugs and retinal functions. II. Effects of phenothiazine and rifampicin on the sheep ERG.

The acute effects of chlorpromazine, promethazine and rifampicin on the a‐, b‐ and c‐waves of the conventional electroretinogram (ERG) were studied in sheep. Iv administration of chlorpromazine and promethazine resulted in a b‐wave amplitude decrease and an initial c‐wave amplitude decrease, followed by cyclic amplitude changes resembling damped oscillations. Iv injections of rifampicin, however, resulted in cyclic changes of the c‐wave amplitude without initial concomitant b‐wave changes. The results of the present study indicate that rifampicin has a selective influence on the pigment epithelial cells, while chlorpromazine and promethazine seem to have more generalized retinal effects on both the neuro‐retina and the pigment epithelial cells.

Factors influencing the formation of posterior capsular opacities after extracapsular cataract extraction with posterior chamber lens implant

Abstract This study was designed to determine whether different factors could influence the formation of posterior capsular opacities. The study group comprised 271 patients who had undergone an extracapsular cataract extraction with implantation of a posterior chamber lens either with or without laser ridge. Between 12 and 25 months after surgery, a statistically significant difference was found with a lower rate of secondary cataract in the laser ridge group, but with respect to advanced secondary cataract, i.e. eyes which needed YAG capsulotomy, no statistically significant difference was found (P‐value 0.99). No association was found between age or sex of patients, different surgeons or complications during or after surgery and the risk of getting a secondary cataract.

Corneal anaesthesia after topical treatment with timolol maleate. A case report.

A 58‐year‐old woman treated with 0.5% timolol for an unilateral open angle glaucoma developed decreased corneal sensitivity in her treated eye. The hyposensitivity disappeared within 4 weeks after removal of timolol but reappeared after renewal of timolol treatment. Corneal sensitivity in the untreated eye was normal all the time.

Timolol-maintenance treatment.

Thirty‐eight patients with ocular hypertension or glaucoma were treated with topical timolol for 12–30 months (mean 20). A long lasting hypotensive effect of timolol eyedrops was found. However a need to increase therapy during the follow‐up period was noted especially in the glaucoma group. Eyes with pseudoexfoliations often required concomitant therapy from the beginning. Ocular side effects were relatively few but four cases of punctate keratitis and another two with decreased corneal sensitivity were observed.

Effects of repeated smoking on dark adaptation.

The influence of cigarette smoking on adaptation of the eye to the dark has been studied in 12 subjects with the aid of an automatic adaptometer. After repeated smoking a slight but significant impairment of dark adaptation in the mesopic range was noticed.