Colour contrast sensitivity in cataract and pseudophakia.

PURPOSE: To study the influence of cataract on peripheral and central colour contrast sensitivity. METHODS: Peripheral and central colour contrast sensitivity was measured with a computer graphics system along the protan, deutan and tritan axes. Included were 30 patients with cataract divided into three sub-groups: cortical cataract, nuclear sclerosis and posterior subcapsular cataract. Colour contrast was measured before and after cataract operation. RESULTS: There were significant differences in peripheral colour contrast thresholds comparing the preoperative and postoperative results. This difference existed even in patients (n=19) with a pre-operative visual acuity > or = 0.5 (mean 0.6). The tritan axis was the one most affected by cataract. There was no significant difference between cataract sub-groups. Also, the central colour contrast sensitivity was affected by cataract. Again, the tritan axis was the most affected one. There was no significant difference between the cataract sub-groups. We also found large and significant differences in central colour contrast thresholds between normal subjects and postoperative values from the cataract group in all colour axes. The colour contrast sensitivity was poorer in pseudophakes than in normals. There was a difference between the three groups of different IOL material used (PMMA, acrylic and silicone). The difference was significant in the protan axis, the acrylic group having the best colour contrast sensitivity. CONCLUSION: Peripheral colour contrast sensitivity was affected by cataract, even when only moderately developed. This finding is of importance and should be considered when the method is used to study other eye diseases e.g. glaucoma. Central colour contrast sensitivity was also affected by cataract. The pseudophakes were found to have poorer colour contrast sensitivity than normals. The material in the IOL seemed to be of importance for colour contrast.

Peripheral and central colour contrast sensitivity in diabetes.

PURPOSE: To study the influence of diabetes, with or without early retinopathy, on peripheral and central colour contrast sensitivity. METHODS: The study included 32 patients with diabetes mellitus type II and 47 age-matched normals. The patients were divided into three sub-groups. 1. Diabetics with no retinopathy (on photographs or biomicroscopy). 2. Diabetics with microaneurysms only. 3. Diabetics with microaneurysms and hard exudates. Colour contrast sensitivity was measured with a computer graphics system along the protan, deutan and tritan axes. RESULTS: The peripheral colour contrast thresholds were significantly elevated for all axes when comparing the group with microaneurysms and exudates to normals. There were also significant differences between the group with microaneurysms and hard exudates and the two other diabetic groups, respectively, but only for the tritan axis. Diabetics with no retinopathy or with microaneurysms only did not differ significantly from normals. The central colour contrast thresholds showed significant differences between normals and the group with microaneurysms, but only for the protan and deutan axes. There were significant differences for all three axes between normals and the group with microaneurysms and hard exudates. There were also significant differences between the group with microaneurysms and hard exudates and the two other diabetic groups, but only for the tritan axis. Diabetics with no retinopathy did not differ significantly from normals. CONCLUSION: Peripheral colour contrast sensitivity was affected by low-grade diabetes type II retinopathy. This finding has to be considered if the method is to be used in screening for glaucoma. The central colour contrast sensitivity test seems to correlate to the degree of retinopathy and thereby perhaps provides a new screening method for diabetes retinopathy. Further studies are required in order to evaluate such a possibility.

Peripheral colour contrast thresholds in ocular hypertension and glaucoma.

PURPOSE: To evaluate a new test for peripheral colour contrast sensitivity as a tool for early diagnosis of glaucoma. PATIENTS AND METHODS: Peripheral colour contrast sensitivity was measured by a computer and colour monitor system developed by Arden and co-workers. The monitor displays an annulus subtending 25 degrees at the retina. During the test, 45 degrees of the annulus is removed in one of four quadrants. The patient is asked to identify this quadrant, first at suprathreshold levels and then as the colour contrast between the annulus and the background is varied in order to establish the threshold for identification. The tested colours were varied along the protan, deutan and tritan colour confusion axes, respectively. Thirty-three normal subjects, 22 glaucoma patients and 69 ocular hypertensive patients were examined. The ocular hypertensive patients were divided into a low risk group, a medium risk group and a high risk group. RESULTS: The colour contrast thresholds for the glaucoma group and the high risk ocular hypertensive group were significantly (p < 0.001) higher for all three colour axes compared with the normal group. There were also significant (p < 0.05-0.001) differences for all axes between the glaucoma group on the one hand and the ocular hypertensive low risk group on the other hand. There were, however, overlaps in colour contrast thresholds between all groups. CONCLUSION: Although there is a large and statistically significant difference in average colour contrast thresholds between normals and glaucoma patients, it was difficult to find an appropriate cut-off point to separate the two groups. Further studies must clarify the influence of early stages of common diseases such as cataract, diabetes and age-related maculopathy on colour contrast sensitivity.

A double masked comparison of the intraocular pressure reducing effect of latanoprost 0.005% and 0.001% administered once daily in open angle glaucoma and ocular hypertension.

AIM: To compare the intraocular pressure (IOP) reducing effect of latanoprost 0.005% and 0.001%. METHODS: Twenty four patients with glaucoma or ocular hypertension were randomised into two groups. Twelve patients (group 1) were given latanoprost 0.005% once daily for 4 weeks and then latanoprost 0.001% once daily for the following 4 weeks. Twelve patients (group 2) were given latanoprost 0.001% once daily for 4 weeks and then latanoprost 0.005% for the following 4 weeks. RESULTS: There was a significant IOP reduction from baseline in both groups on day 28 as well as on day 56. When the results from both groups were used for calculations, the mean IOP reduction from baseline after 4 weeks of treatment with latanoprost 0.005% (day 28 or 56) was 9.6 (SD 3.3) mm Hg (35.0%). After 4 weeks of treatment with latanoprost 0.001%, the IOP reduction (day 28 or 56) was 7.6 (3.4) mm Hg (27.7%). The difference in IOP reduction between the two concentrations was 2.0 (2.3) mm Hg (p < 0.001). CONCLUSIONS: Latanoprost 0.005% was more effective than latanoprost 0.001% in reducing IOP. Even the lower concentration was surprisingly effective, and potentially may be of importance for use in clinical practice. Furthermore, it is at present unknown whether the increase in iris pigmentation seen in certain patients treated with latanoprost 0.005% is dose dependent and might be less pronounced with latanoprost 0.001%. Long term studies with a larger number of patients are required in order to answer this question.

A 6-month, randomized, double-masked comparison of latanoprost with timolol in patients with open angle glaucoma or ocular hypertension.

The intraocular pressure reducing effect and side-effects of latanoprost, a phenyl-substituted prostaglandin analogue, were compared with those of timolol, in a group of 31 glaucomatous or ocular hypertensive patients, divided into three subgroups. The study was randomized and double masked. At the end of 6 month's treatment with latanoprost 0.005% once daily, either as a morning dose or as an evening dose, there was a reduction in intraocular pressure of 33% (p < 0.001) and 36% (p < 0.001), respectively. The intraocular pressure reduction of timolol 0.5%, administered twice daily was 26% (p < 0.001). There was no significant difference in conjunctival hyperemia between the groups and there were few subjective symptoms in any of the patients. One patient with a light green-brown iris, treated with latanoprost in one eye only, exhibited an increase in iris colour in the treated eye at week 26, and did not show any signs of reversion 9 months after discontinuing the therapy. It may be concluded that latanoprost is well tolerated and at least as effective as timolol in reducing intraocular pressure in patients with glaucoma or ocular hypertension when applied once daily. The exact mechanism behind the increase in iris pigmentation and the clinical significance of this previously unknown side-effect needs to be investigated further.

Latanoprost administered once daily caused a maintained reduction of intraocular pressure in glaucoma patients treated concomitantly with timolol.

The long term effects of two dose regimens of latanoprost (PhXA41) administered to eyes concomitantly treated with timolol which had not adequately been controlled by timolol alone were compared. A total of 50 patients, 17 with primary open angle glaucoma and 33 with capsular glaucoma, were recruited from five clinics. All had glaucomatous visual field defects and an intraocular pressure (IOP) of at least 22 mm Hg despite treatment with 0.5% timolol twice daily. Patients were randomised to two treatment groups. In one group 0.006% latanoprost was given twice daily, in the other group placebo was given at 8 am and latanoprost at 8 pm for 3 months, with concomitant timolol treatment in both groups. Average daytime IOP (mean (SD)) at baseline (on timolol alone) and after 4 and 12 weeks' treatment was 24.8 (3.6), 16.8 (4.3), and 15.7 (2.4) mm Hg respectively with once daily application of latanoprost and 24.9 (2.9), 18.1 (3.0), and 18.0 (3.6) mm Hg respectively with latanoprost twice daily. No clinically significant side effects were observed during treatment. Latanoprost causes a marked and sustained IOP reduction in eyes which are also being treated with timolol. Latanoprost given once daily is at least as effective and probably superior to a twice daily dose regimen.

Interaction of PhXA41, a new prostaglandin analogue, with pilocarpine. A study on patients with elevated intraocular pressure.

OBJECTIVE: To evaluate the effects of PhXA41, a new prostaglandin analogue, on the intraocular pressure (IOP) in patients receiving pilocarpine treatment and the effects of pilocarpine in patients receiving PhXA41 treatment. DESIGN: Twenty patients with ocular hypertension were randomized into two parallel groups. The treatment period was 2 weeks. Ten patients in group 1 were given PhXA41 twice daily during week 1 and, in addition, pilocarpine three times daily during week 2. Ten patients in group 2 received pilocarpine three times daily during week 1 and PhXA41 twice daily in addition during week 2. PhXA41 was used in a concentration of 0.006%, and pilocarpine was given in a concentration of 2%. MAIN OUTCOME MEASURES: In group 1, the mean IOP on day 0 was 25.1 mm Hg; on day 7, 19.1 mm Hg; and on day 14, 17.6 mm Hg. In group 2, the mean IOP on day 0 was 23.8 mm Hg; on day 7, 20.4 mm Hg; and on day 14, 17.7 mm Hg. RESULTS: PhXA41 had a clinically significant IOP-lowering effect (23.4% reduction on day 7 as compared with baseline day (P < .001). The corresponding value with pilocarpine was 14.3% (P < .001). When pilocarpine was added to PhXA41, the additional IOP reduction was 7.4% (P < .01) compared with 14.2% (P < .01) when PhXA41 was added to pilocarpine. The two groups were found to have an almost equal reduction in IOP on day 14 (group 1, 29.4%; group 2, 26.6%). No serious adverse reactions were seen. Some conjunctival hyperemia in the PhXA41-treated eyes was noted on day 7, as compared with the pilocarpine-treated eyes, but there were few complaints of discomfort. CONCLUSIONS: This study indicated that PhXA41 could be useful in the treatment of glaucoma, as monotherapy, or in certain cases in combination with pilocarpine.

Double point test with the Goldmann perimeter.

A simple accessory to the Goldmann perimeter, permitting simultaneous projection of two targets, is described. The method can be used as a colour saturation test but also for the study of inattention hemianopia. Two cases illustrate its clinical application.