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Catherine A Cukras, Janani Singaravelu, Jason Alvarez, Wai T Wong; Pilot Study to Evaluate Oral Minocycline as a Treatment for Cystoid Macular Edema Associated with Retinitis Pigmentosa. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3261. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Retinitis pigmentosa (RP) is a genetically heterogeneous category of inherited photoreceptor degenerations in which up to one-third of patients demonstrate cystic macular edema (CME) which has been associated with central vision loss. The etiology of RP-associated CME has been related to retinal neuroinflammation and microglial activation. Minocycline, a FDA-approved antibiotic, exerts off-label inhibition of microglial activation and decreases inflammatory factor production. The objective of this study is to investigate the safety and possible efficacy of oral minocycline as a primary treatment for CME in RP.
A single-center, prospective, open-label Phase I/II clinical trial enrolled five participants with bilateral cystic macular edema (CME) associated with RP, with one eye assigned as the “study eye” and the contralateral eye as the “fellow eye”. Participants were followed monthly for 3 months off-drug and then administered oral minocycline 100 mg twice daily for 12 months. Main outcome variables included changes in best corrected visual acuity (BCVA) and retinal central subfield thickness (CST) measured using spectral domain optical coherence tomography (SD-OCT) relative to mean pretreatment measurements.
The study drug was well tolerated and not associated with any significant adverse events. No significant changes in mean BCVA were noted in either the study eye (+0.7±4.1 letters at 6 months, -1.1±1.7 letters at 12 months) or the fellow eye (-0.3±3.4 letters at 6 months and -0.3±4.6 letters at 12 months)(P>0.05 for all comparisons). Changes relative to baseline were <10 letters for all eyes. Mean percentage changes in CST however decreased progressively with time on treatment (decreases for 2, 4, 6, 8, 10, and 12 months were: study eyes, 4.4, 6.0, 4.7, 7.4, 11.4, 11.5%; fellow eyes, 2.0, 4.6, 1.3, 8.5, 5.7, 7.6, 6.9%). Considering all eyes (n = 10), mean percentage CST decrease at 6 and 12 months were -2.7±9.4% (p=0.63) and -8.7+9.5% (p=0.03) respectively.
Minocycline administration over 12 months was associated with no significant changes in mean visual acuity and a small but progressive decrease in mean central macular thickness. Further study is needed to determine whether minocycline is a potentially useful mode of intervention for macular edema in the setting of RP.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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