Purchase this article with an account.
I. Grierson, K.P. Cracknell, P.A. Hogg; Does the Latanoprost Darkened Iris Differ in Morphology From the Normal Iris? . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3766.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: The irides from susceptible individuals when treated with latanoprost have been found to undergo the latanoprost induced iris darkening (LIID) side effect. The aim of this study is to compare the morphology of these color change irides with that found in the normally colored eye, in order to gain an insights on the mechanism that brings about this color change and to find if it is consistent with that seen in normally dark irides. Methods: Iridectomy samples were obtained from surgical trabeculectomy procedures for 15 latanoprost induced color change cases, confirmed by photographic record. Normal eye color controls were and from enucleated eyes where an iridectomy sample was removed, this group was made up of 5 homogeneous blue, 5 homogenous browns and 5 heterogeneous irides (green/brown). The samples were processed for routine electron microscopy. A series of electron micrographs were taken for each sample, which were then analyzed with an image analysis package. For each sample, measurements were made of the iris stromal cellularity and stromal melanocyte size. Further analysis was carried out on the number and size of the melanin granules within the stromal melanocytes. Results: Detailed morphometric analysis has been carried out on the normal untreated irises to determine what are the differences between the different eye colors. We have found that in the blue irides the melanocytes have sparse numbers of small melanin granules, there was found to be small variance within this group. The heterogeneous group had a large spread of the number and sizes of granules between the members of the group, though without exception they were more numerous and had a larger mean size than those in blue irides. There was a degree of overlap between the brown and heterogeneous groups, but on the whole the brown irides had the largest and most numerous melanin granules. With the LIID group there was found to be no statistical difference in the number of granules when compared to both the heterogeneous and brown control groups. When the size of the granules were examined a significant increase was found in the anterior border region, when compared to both the heterogeneous and brown control groups. Conclusions: In a naturally brown eye there are more melanin granules, as compared to the other colors. In the LIID effect the numbers of granules are unaffected, but the individual granules are increased in size. This difference however is still quite subtle, with the enlargement of the mean size of the melanin granules being within the normal range of iris melanocyte granule size.
This PDF is available to Subscribers Only