Jody Piltz

Nimodipine, a centrally active calcium antagonist, exerts a beneficial effect on contrast sensitivity in patients with normal-tension glaucoma and in control subjects

BACKGROUND/PURPOSE The use of calcium antagonists in patients with normal-tension glaucoma (NTG) currently is under investigation. The aim of this study is to evaluate the effect of an acute dose of oral nimodipine, a centrally active calcium antagonist, on spatial contrast sensitivity in patients with NTG and in age-matched control subjects. METHODS Spatial contrast sensitivity was measured using the Pelli-Robson and the Vistech 6000 charts in 14 patients with NTG and in 17 control subjects. Testing was performed at baseline and at two subsequent sessions. Measurements were recorded 2 hours after oral administration of either nimodipine or placebo in a randomized, double-masked manner. Data were analyzed using unpaired, two-tailed Students t test for between-group comparisons and repeated measures analysis of variance for within-group comparisons. RESULTS Using the Pelli-Robson charts, baseline contrast sensitivity was significantly lower in patients with NTG compared with control subjects (P < 0.05, unpaired Students t test). There was a significant increase in log contrast sensitivity after administration of nimodipine compared with baseline and placebo in patients with NTG (baseline, 1.39 +/- 0.38; placebo, 1.41 +/- 0.40; nimodipine, 1.51 +/- 0.39) and in control subjects (baseline, 1.62 +/- 0.11; placebo, 1.64 +/- 0.10; nimodipine, 1.81 +/- 0.14) (P < 0.05, repeated measures analysis of variance). A similar trend was observed using the Vistech charts. CONCLUSION These results suggest that central visual function as measured by Pelli-Robson and Vistech contrast sensitivity is impaired in eyes with NTG. An acute, oral administration of nimodipine, a calcium antagonist, improved contrast sensitivity in patients with NTG and in control subjects. The mechanism of this improvement is not fully understood. Further studies are needed to evaluate the effect of long-term administration in glaucoma.

Contralateral effect of topical β-adrenergic antagonists in initial one-eyed trials in the Ocular Hypertension Treatment Study

PURPOSE To evaluate the magnitude of the contralateral effect of topically administered beta-blockers on intraocular pressure. METHODS The Ocular Hypertension Treatment Study enrolled 1,636 subjects. Of these, 817 subjects were randomized to receive topical ocular hypotensive medication and 819 subjects were randomized to close observation (i.e., no topical medication). We compared the intraocular pressure of the contralateral eye of subjects at the baseline visit and after an initial one-eyed therapeutic trial of topical beta-blockers. We examined differences between baseline and follow-up intraocular pressure in untreated eyes of subjects randomized to close observation. RESULTS The mean reduction in intraocular pressure in the beta-blocker-treated eyes was -5.9 +/- 3. 4 mm Hg (-22% +/- 12%; Student t test, P <.0001). In the contralateral eyes, mean intraocular pressure reduction was -1.5 +/- 3.0 mm Hg (-5.8% +/- 12%; P <.0001). Of the contralateral eyes, 35% showed a reduction of 3 mm Hg or more, and 10% showed a reduction of 6 mm Hg or more. The contralateral effect of the relatively selective beta-blocker betaxolol did not differ from that of any of the nonselective beta-blockers. Factors associated with the magnitude of the contralateral effect were the degree of intraocular pressure reduction in the treated eye and baseline intraocular pressure of the contralateral eye. In the close observation group, no significant reduction in intraocular pressure was noted between the baseline and follow-up visit. CONCLUSIONS The contralateral effect is important in clinical practice and in clinical trials when the hypotensive effect of a topical beta-blocker is evaluated by means of a one-eyed therapeutic trial.

Computerized stereochronoscopy and alternation flicker to detect optic nerve head contour change

PURPOSE/BACKGROUND Stereochronoscopy, a technique previously explored but abandoned for glaucoma diagnosis, viewed optic nerve images acquired at separate points in time as if a stereo pair. Prior efforts to exploit this technique were impaired by a lack of superimposability for sequential optic nerve images. We investigated computerized registration techniques for aligning sequential, monoscopic optic disc images to facilitate sensitive detection of optic nerve head contour changes in glaucoma. DESIGN Algorithm and software development. Comparisons with standard techniques. MATERIALS Existing patient records from the Glaucoma Service, Scheie Eye Institute, University of Pennsylvania. METHODS Two sets of optic disc photographs, separated in time by 1 to 18 years, of 25 eyes with and without glaucomatous optic disc progression were digitized. We developed custom software for accurate image alignment. Change in disc morphology was then judged by digital stereochronoscopy and user-controlled alternation flicker of superimposed, time-separated images on a computer monitor. Comparisons were made with standard stereoscopic comparison. MAIN OUTCOME MEASURE Identification of change or no change in optic nerve head contour for images acquired at separate points in time. RESULTS Image processing and registration permits accurate alignment of optic disc photographs. Alternation flicker of superimposed, sequential images facilitates image comparison and detection of change as indicated by change in vessel position, color, and other cues for contour change. A high concordance was found between standard stereoscopic comparison and alternation flicker. In several cases, reinspection of stereo comparison led to a revised judgment on the basis of disc changes rendered more obvious with alternation flicker. Digital stereochronoscopy was less concordant with standard techniques. CONCLUSIONS Digital image processing techniques and alternation flicker provide a simple, sensitive, software-based method for detecting glaucomatous optic disc change.

Acute effects of sldenafil ctrate (Viagra®) on intraocular pressure in open-angle glaucoma

PURPOSE To assess the acute effects of sildenafil citrate (VIAGRA) on the intraocular pressure (IOP) of patients with chronic open-angle glaucoma. DESIGN This was a double-blind, randomized, placebo-controlled, crossover study, in which 15 patients received a single oral dose of sildenafil 100 mg or matching placebo on two separate occasions. METHODS Fifteen subjects aged 63 +/- 14 years (mean +/- SD) with bilateral chronic open-angle glaucoma were administered a single oral dose of sildenafil 100 mg or matching placebo on two separate occasions at least 3 days apart. IOP was measured in both eyes by Goldmann ap-planation tonometry at baseline and then at 1-5 hours after dosing. Brachial artery systolic and diastolic blood pressures were determined by sphygmomanometry, and heart rate was also monitored at baseline and 1-5 hours after dosing. RESULTS Compared with placebo, no statistically or clinically significant change in IOP was detected after a single dose of sildenafil 100 mg (P =.20). Moreover, no significant change in mean systemic blood pressure (P =.12) or heart rate (P =.72) was detected after treatment with sildenafil. CONCLUSION At the maximum therapeutic dose of 100 mg, sildenafil did not produce any significant acute change in IOP in men with chronic open-angle glaucoma. This information is of importance for patients with glaucoma receiving sildenafil for treatment of erectile dysfunction.