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Priscilla Quynh-Phuong Vu, Thomas A Vo, Donald S Minckler; Initial clinical assessment of the effect of prior timolol use on penatrating keratoplasty outcome in Acanthamoeba Keratitis.. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3693.
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Acanthamoeba keratitis is a vision threatening disease that can cause rapid blindness. Diagnosis is often delayed but eventually accurate in most via confocal microscopy or histology on epithelial scrapings or corneal biopsy. Current treatment guidelines recommend multiple topical antiseptic, antifungal and antibiotic agents; however, compliance is challenging as it requires up to hourly drops for multiple days until clinical clearing which can take weeks. This regimen often fails and recurrence of inflammation may recur with or without cysts even after penetrating keratoplasty (PK). A recent laboratory study1 suggests topical timolol is amoebicidal for this organism, but this has yet to be reported clinically.
This is a retrospective case-control study of all patients with histologically proven Acanthamoeba keratitis at an academic hospital. Biopsies were from corneal buttons from penetrating keratoplasty. The rates of repeat corneal transplant were compared between patients using and not using timolol drops. This study also evaluated the relationship between timolol exposure and other clinical findings such as presence of hypopyon, ring ulcer, keratic precipitates, and uveitis.
Across our 18 cases, 15 cases had no recurrent inflammation requiring repeat corneal transplant (83.3%) and 3 had repeat graft inflammation requiring a 2nd transplant (16.7%). 6 cases (33.3%) had a history of timolol eye drop use and 12 cases (66.7%) had no history of timolol use. 2 of 6 cases (33.3%) with timolol use and 1 of 12 cases (8.3%) without timolol use had recurrent inflammation and repeat PK. Timolol exposure was not associated significantly with increased recurrent inflammation and repeat PK. Presence of hypopyon, ring ulcer, keratic precipitates, and uveitis was also not associated timolol exposure.
This study did not support timolol being advantageous or amoebicidal. Small sample size and retrospective design limit the value of this study. Future studies will include larger sample size and further evaluate timolol as a potentially valuable alternative or adjunct to present therapy.References: 1. Sifaoui I et al. Evaluation of the anti-Acanthamoeba activity of two commercial eye drops commonly used to lower eye pressure. Exp Parasitol. 2017 Aug.Authors acknowledge departmental support from an RPB unrestricted grant.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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