Dose response and duration of action of dorzolamide, a topical carbonic anhydrase inhibitor.

The multiple-dose, dose-response relationship and duration of action of the novel topical carbonic anhydrase inhibitor dorzolamide (previously known as MK-507) were investigated in a double-masked, randomized, placebo-controlled, parallel study in 73 patients with bilateral primary open angle glaucoma or ocular hypertension. Dorzolamide (0.7%, 1.4%, or 2%) or placebo was administered every 12 hours for 5 days and then every 8 hours for 7 days. Intraocular pressure was investigated with multiple 12-hour diurnal curves. All concentrations of dorzolamide demonstrated substantial lowering of intraocular pressure throughout the day when given twice daily (9% to 21%) or three times daily (14% to 24%). Although a dose-dependent response was observed immediately following the first dose, there were no significant differences between concentrations or dose response at either the twice or three times daily dosing regimen. Three times daily administration of 2% dorzolamide demonstrated a mean percent decrease in intraocular pressure of 18% to 22% throughout the day (mean decrease, 4.5 to 6.1 mm Hg). Dorzolamide appears to have substantial potential in the treatment of glaucoma and ocular hypertension.

Computerized patient record system for the glaucoma ward.

A system for computerized glaucoma patient record, developed from a data base called 'Advanced Revelation', is described. The record is made up from free text as well as from choices among listed alternatives. All data are stored on magnetic media and also printed out on paper in a well disposed and easily surveyable form. Apart from saving personnel and time in the clinical routine, the main advantages of the system is a powerful tool for clinical research. Data retrieval occurs on 'list', 'count', or 'sort' orders, facilitating retrospective studies. The system has been used for over a year at a glaucoma ward (Lund) to increasing satisfaction.

Occurrence of disc haemorrhages in open-angle glaucoma treated with pilocarpine or timolol.

1573 examinations were performed on 397 eyes. hh was found in 55 eyes--thromboses included--at 91 examinations. Part of this material qualified for use in a comparative study with pilocarpine in 81 eyes and timolol in 82 eyes. The relative frequency of hh in the treated groups and in the pretreatment group was not significantly different from that of the whole material. No indication of pressure reduction with effect on the occurrence of hh could be detected. The average probability of hh at an examination chosen at random was 6 per cent in this material of ordinary simple and capsular glaucoma cases. The occurrence of haemorrhages in relation to age, sex, general hypertension and diabetes are discussed.

Treatment versus no treatment in chronic open angle glaucoma.

In a controlled randomized study 15 patients (20 eyes) with chronic open angle glaucoma and visual field defects were followed by greater than 1 year, 12 of them were followed for 3 years. Half of the group were untreated controls, the other half treated with pressure reducing medical therapy. At least 5 consecutive computerized visual fields were recorded (COMPETER) on each eye, and the linear regression coefficient was calculated. With the reservation for uncontrolled compliance no significant difference in the line of favourable effect of pressure reduction could be spotted, in spite of an average pressure reduction in the treated group of 4 mmHg. More important than this result, which is open to criticism for the smallness of the material, uncontrolled compliance etc, is the lesson that a randomized experiment with treated and non-treated glaucoma cases carried out in accordance with the Helsingfors convention is hardly feasible.

A system for a computer-assisted glaucoma care unit.

A computerized system for a glaucoma care unit is described. The aim is to examine and record every patient classified as a case of glaucoma in a way which permits subsequent use of the data in studies of the natural history of glaucoma. A main topic concerns the choice of those examinations, treatments etcetera which have to be included in the records to satisfy clinical and scientific requirements. The system is distensible by allowing the introduction of new parameters to be introduced. Graphic presentation of IOP and visual field development over long periods improve the surveyability to a large measure. So far about 200 patients from the glaucoma care unit have been included in the system.

Trabeculoplasty and visual field decay: a follow-up study using computerized perimetry.

15 eyes with glaucomatous visual field defects were followed with computerized perimetry before and nearly one year after Argon Laser Trabeculoplasty. An expected reduction of the IOP was achieved, the pressure being on an average 25.7 mm Hg before and 17.7 after the treatment. Performance values obtained at computerized perimetry were used to trace the trend of visual field development. There was a visual field decay during the period preceding the intervention. This trend did not change after trabeculoplasty.

Laser trabeculoplasty in open angle glaucoma. A short term study using computerized perimetry.

In 23 eyes with glaucomatous field defects laser trabeculoplasty was performed. Applanation tonometry and computerized perimetry were carried out before and after the treatment. No favourable influence on the visual field could be demonstrated one month after the treatment, in spite of satisfying pressure regulation.

The visual field after trabeculectomy. A follow-up study using computerized perimetry.

Series of visual fields in 20 eyes in which trabeculectomy had been performed were studied retrospectively. Computerized perimetry was used and the condition of the visual field was summarized into single numbers. Regression analysis was applied to series of such performance numbers. No correlation was found between the regression coefficient and the mean post-operative pressure or the mean pressure reduction. A dependence of the regression coefficient on the size of the visual field defect was observed.

The glaucoma theory updated.

The natural history of splinter haemorrhages on the optic disc is an argument in favour of the belief that the glaucomatous process starts in the small vessels of the papilla. The probable existence of factors in the aqueous, whose generation depend on the state of oxygenation in the posterior parts of the eye and which affect the outflow resistance, supports the idea that the pressure increase is a secondary effect. Reduced perfusion by increased IOP or reduced blood pressure etc. is likely to accelerate a process already begun in the papilla.

Short term effects of timolol in chronic glaucoma. A double blind study using computerized perimetry.

15 patients with glaucomatous field defects in at least one eye were subjected to computerized perimetry and IOP, systemic blood pressure and pulse rate measurements before and after timolol or placebo instillation in both eyes. A significant decrease of IOP and pulse rate was found 2 h after timolol. The visual fields were not improved, the correlation between IOP and visual field performance being (though not significantly) positive. The lack of improvement could not be attributed to the decrease in pulse rate.

Regression analysis of the central visual field in chronic glaucoma cases. A follow-up study using automatic perimetry.

90 glaucoma cases (160 eyes) with field defects in at least one eye have been subjected to automatic perimetry on at least 5 occasions. The condition of the field defect is represented by the regression coefficient. The frequency distribution of the coefficients in groups based on references to age, sex, intraocular pressure, exfoliations, haemorrhages and therapy illustrates the possible importance or insignificance of these factors to the decay. The need for several consecutive examinations to establish with some significance a progression of field defects is demonstrated.

Optic disc evaluation versus the visual field in chronic glaucoma.

A classification of the optic disc (the upper and lower half treated separately) was performed independently by 3 observers. The material consisted of 40 single colour photographs of eyes with glaucomatous field defects and of fellow eyes. The consistency between the observers was found to be good. The sensitivity for the detection of visual field defects from the appearance of the corresponding disc half was 75%. The specificity was 85%.

Disc haemorrhage and glaucoma.

The present material comprises 51 patients with at least one disc haemorrhage in at least one eye. A total of 127 hh were observed. The probability of finding a disc h increases with the number of examinations. The hypothesis that hh occur in all cases of glaucomatous destruction of the papillary tissue cannot be rejected, though not proven. H. seems to be connected with progression of field defects, though its effects are not immediately recognized. H. is detectable very early in the glaucomatous process; the denotation 'forerunner' is most likely justified. Hh. are highly specific for a glaucomatous process, but it has not been possible to connect h. with some clearly delimited group of glaucoma.

Visual field decay in normal subjects and in cases of chronic glaucoma.

Visual field information obtained with the automatic Computer-Perimeter ('Competer') can be condensed into a single numerical value. This performance measure was applied to a normal population to determine the physiologic decay of retinal sensitivity with aging. Further, the development of this performance measure was followed in 54 glaucoma eyes which were divided into three groups: Untreated, treated with satisfactory intraocular pressure (IOP) regulation, and treated with satisfactory IOP regulation. All eyes were examined perimetrically on at least three separate occasions. Decaying performance measures were found in the preponderance of glaucoma eyes. Therapy aimed at lowering the IOP did not offer a protective effect. Papillary hemorrhage and a significant decay in performance are usually found in the same eye.

Computerized meridian perimetry. A preliminary report.

By a modification of the display of test points it is possible to use the computerized perimeter "Competer" for meridian testing. The test program gives estimates of the thresholds in two separate rounds, the second starting when the first is completed. Accordingly two profiles are plotted in the meridians tested. Furthermore a smoothed profile is drawn from the mean values of the two rounds. The outcome when testing normal subjects and cases with glaucomatous defects was studied and the stability of thresholds in normals and the decay in scotomatous areas with time is demonstrated.

Variability of glaucomatous visual field defects in computerized perimetry.

Normal subjects are able to maintain a stable level of performance throughout a test session of 30 min, using 0.5 s exposure time. Test points placed in normal areas of glaucoma cases behave similarly, whereas test points in relative scotomatous parts of the field show not only a lower sensitivity level but also a tendency to a decline of the performance level and/or a higher threshold variation. Change of exposure time showed remarkable effects on the performance level at defect points, an increase to 1 s causing a stabilization on an improved level and a decrease to 0.25 s giving a deterioration. The results are discussed in terms of noise admixture to the signal. According to this model an increased noise amplitude by impaired retinal function reduces the performance level and augments the variation. On the other hand, an increased exposure time of the test object, which causes a stabilization of the process on an improved performance level, may be interpreted as a reduction of the noise amplitude.