Fine structural evaluation of the iris after unilateral treatment with latanoprost in patients undergoing bilateral trabeculectomy (the Mainz II study).
OBJECTIVE
To investigate by masked electron microscopy whether 6 months of topical latanoprost caused pathological changes in the peripheral iris of patients with glaucoma.


METHODS
Seventeen patients with bilateral primary open-angle glaucoma requiring trabeculectomy were recruited for this study. The iridectomy taken during surgery on the first eye served as a control. The second test eye was treated topically with latanoprost for 6 months before its trabeculectomy. Fourteen patients completed the treatment arm of the study, and 1 of these underwent marked color change. As a result, 31 iridectomy specimens were fixed, coded, and evaluated.


RESULTS
The specimens were evaluated for evidence of stromal inflammation, vascular alterations, and stromal and posterior epithelial degeneration. None of these features was evident in any of the 31 iridectomy specimens. There was evidence of the incidence of free melanin granules in the stroma, melanin turnover, abundance of stromal clump cells, atypical cellular features in melanocytes, and prominence of the anterior border. After code breaking, it was evident that none of these features distinguished the test from the fellow irises in our group. The patient with color change in the test iris did not stand out from the others in this analysis. Qualitative reexamination of further sections after unmasking gave the impression of increased melanin granule numbers in the melanocytes of the anterior border region.


CONCLUSIONS
The ultrastructure of the iridectomies from the latanoprost-treated eyes and the fellow eyes conformed to published standards for normal iris. There was no evidence of early ultrastructural changes, which might have been the harbingers of latanoprost-induced iris abnormality.
Pfeiffer
Norbert
N
Department of Ophthalmology, Johannes Gutenberg-Universität, Langenbeckstrasse 1, 55131 Mainz, Germany. pfeiffer@augen.klinik.uni-mainz.de
Grierson
Ian
I
Goldsmith
Helen
H
Appleton
Paul
P
Hochgesand
Dirk
D
Winkgen
Andrea
A
D000287:Administration, Topical; D000368:Aged; D000959:Antihypertensive Agents / Q000009:adverse effects / Q000627:therapeutic use*; D004311:Double-Blind Method; D017889:Exfoliation Syndrome / Q000150:complications; D005260:Female; D005902:Glaucoma, Open-Angle / Q000188:drug therapy* / Q000601:surgery*; D006801:Humans; D007498:Iris / Q000187:drug effects / Q000601:surgery / Q000648:ultrastructure*; D000077338:Latanoprost; D008297:Male; D008543:Melanins / Q000378:metabolism; D008544:Melanocytes / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D008875:Middle Aged; D011461:Prostaglandins F, Synthetic / Q000009:adverse effects / Q000627:therapeutic use*; D014130:Trabeculectomy
D000959:Antihypertensive Agents; D008543:Melanins; D011461:Prostaglandins F, Synthetic; D000077338:Latanoprost