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Peripheral colour contrast thresholds in ocular hypertension and glaucoma
Linköping University, Department of Neuroscience and Locomotion, Ophthalmology. Linköping University, Faculty of Health Sciences.
1997 (English)In: Acta Ophthalmologica Scandinavica, ISSN 1395-3907, E-ISSN 1600-0420, Vol. 75, no 4, 376-382 p.Article in journal (Refereed) Published
Abstract [en]

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° at the retina. During the test, 45° 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.

Place, publisher, year, edition, pages
1997. Vol. 75, no 4, 376-382 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:liu:diva-80117DOI: 10.1111/j.1600-0420.1997.tb00393.xOAI: diva2:545673
Available from: 2012-08-21 Created: 2012-08-21 Last updated: 2012-08-21Bibliographically approved
In thesis
1. Aspects of the diagnosis and treatment of glaucoma
Open this publication in new window or tab >>Aspects of the diagnosis and treatment of glaucoma
2001 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Glaucoma is one of the most common causes of blindness in the world, and it is important that screening tests as well as treatment possibilities are improved continuously. A reliable but more rapid screening test than those already available would be of great interest. In addition, new and more effective treatment options would be most valuable. The aims of the present thesis were to evaluate the reliability of a new and rapid peripheral colour contrast sensitivity test as a tool for glaucoma screening and to gain more information on latanoprost, a recently developed prostaglandin analogue, in glaucoma treatment.

Colour contrast sensitivity was analysed with a system described by Arden and co-workers, using a computer controlled colour monitor. The test objects for the central test were letters of standard optotype subtending a visual angle of 3° . For the peripheral test, the test object was a colour contrasting annulus concentric with a fixation spot. The annulus had a radius of 12.5° in the extramacular field and a width of 1°. The colour contrast of the letter or the annulus in relation to the background could be changed, and a colour contrast threshold value could be obtained in the protan, deutan and tritan colour axes.

In a study of glaucoma patients, ocular hypertensive patients and normals, the peripheral colour contrast sensitivity test was found to distinguish the glaucoma patients from the normals. However, it was difficult to find a reliable cut-off point if the test is to be used as a screening test.

In a five-year prospective study of ocular hypertensive patients, the peripheral colour contrast sensitivity test could not clearly predict which patients would develop glaucoma and which would not, given that the Glaucoma Herrrifield Test is used as the golden standard. A change over time in the protan axis may, however, indicate glaucoma development. For a test to be used in glaucoma screening, it is necessary to know whether other common eye diseases such as diabetes and cataract affect the outcome. Therefore, the influence of diabetes and cataract on peripheral and central colour contrast sensitivity was also studied.

Diabetes type II was found to affect both peripheral and central colour contrast sensitivity, the tritan axis being the most affected one. For the tritan axis, the central colour contrast sensitivity seemed to correlate well with the degree of diabetic retinopathy, indicating the possibility of a new functional test of diabetic retinopathy.

Cataract, even moderately developed, affected both peripheral and central colour contrast sensitivity. Central colour contrast sensitivity seemed to be poorer in pseudophakic eyes than in normal eyes. Thus, both diabetes type II and moderate to severe cataract must be considered if the colour contrast sensitivity test is to be used for glaucoma screening. The choice of material for the IOL may also be of importance for postoperative central colour contrast sensitivity.

The prostaglandin analogue latanoprost effectively reduces the IOP at the original concentration of 0.005%. However, several patients need additional treatment. Therefore, the effect of pilocarpine in combination with latanoprost was studied. When pilocarpine was added to latanoprost, there was an additional reduction in the intraocular presure (IOP) (7.4%), and when latanoprost was added to pilocarpine the reduction was even more pronounced (142%). Therefore, it seems that latanoprost and pilocarpine can be combined in glaucoma treatment.

In certain eyes, an increased iris pigmentation was seen as a side-effect of latanoprost. This side-effect may be dose-dependent. Therefore, the original concentration of 0.005% was compared to a lower concentration, 0.001%. Latanoprost 0.005% was more effective than latanoprost 0.001% in reducing the IOP. However, the lower concentration was sufficiently effective to have a potential for clinical use in many patients. Latanoprost 0.005% gave an lOP reduction of 35% after four weeks of treatment, which was in agreement with earlier results. The lower concentration was, however, surprisingly effective and gave an IOP reduction of 27.7%.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2001. 49 p.
Linköping University Medical Dissertations, ISSN 0345-0082 ; 690
National Category
Medical and Health Sciences
urn:nbn:se:liu:diva-28033 (URN)12794 (Local ID)91-7219-983-0 (ISBN)12794 (Archive number)12794 (OAI)
Public defence
2001-10-05, Berzeliussalen, Universitetssjukhuset, Linköping, 13:00 (Swedish)
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2012-08-21Bibliographically approved

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