Meems, W. (2014) Laterale inhibitie in het gezonde oog van de ouder wordende mens. thesis, Medicine.
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Abstract
Background Glaucoma is a chronic optic neuropathy. One of the clinical signs is excavation of the papilla. If left untreated, this condition will progress to blindness. Often, the structural damage occurs at an early stage and the symptoms occur only at a late stage. The current gold standard to diagnose glaucoma, ‘perimetry', shows functional abnormalities at a later stage of the disease. Therefore it is important to develop a method to detect the damage in an early stage. In glaucoma, the signaling between the different cells in the retina is disturbed. These cells are involved in contrast and movement vision. Examples of signal processing in the retina are spatial summation and lateral inhibition. Research showed a different spatial summation between healthy subjects and glaucoma patients. Lateral inhibition has never been studied in glaucoma. In this study the normal values for lateral inhibition will be determined in healthy subjects. Material en method In this cross-sectional study the normal range of lateral inhibition in healthy subjects between 40 and 70 years was determined. The first experiment was based on contrast sensitivity with spatial frequencies of 1 and 4 cycles per degree (cpd). The difference in the contrast between 4 and 1 cpd is a measure of lateral inhibition. A second experiment is the illusory movement experiment. A certain non-moving stimulus can be seen as movement as a result of lateral inhibition. The strength of the ‘illusory movement’ can be measured by compensation with a real movement. The size of the real movement (‘compensation amplitude') is also a measure of lateral inhibition. Results Fifty subjects with a mean age of 55 years were included. The contrast sensitivity experiment with a spatial frequency of 1 cpd showed a nonsignificant increase in contrast sensitivity with age from log contrast sensitivity 2,03 to 2,12. For the spatial frequency of 4 cpd values decreased nonsignificantly with age from log contrast sensitivity 2.52 to 2.40. The difference in contrast sensitivity between 4 and 1 cpd, a measure of lateral inhibition, decreased significantly with age from log contrast sensitivity 0.48 to 0.27. The illusory movement experiment showed a nonsignificant decrease in the compensation amplitude with age. The value was between -9,1 and -3,7 arcseconds. Conclusion In conclusion, this study determined the normal values for contrast sensitivity in older age. The contrast sensitivity experiment showed a nonsignificant increase of the contrast sensitivity with age for 1 cpd and a nonsignificant decrease of the contrast sensitivity with age for 4 cpd. The difference in the contrast sensitivity showed a significant decrease with age. The illusory movement experiment showed no significant change in the compensation amplitude with age.
| Item Type: | Thesis (Thesis) |
|---|---|
| Supervisor name: | Junoy Montolio, drs. F.G. and Jansonius, prof. dr. N.M. |
| Faculty: | Medical Sciences |
| Date Deposited: | 25 Jun 2020 10:44 |
| Last Modified: | 25 Jun 2020 10:44 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/601 |
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