The use of selective serotonin reuptake inhibitors to treat amblyopia in adulthood

Abstract

Purpose: Selective serotonin reuptake inhibitors (SSRIs) can enhance visual cortex plasticity and promote recovery of vision in animal models of adult amblyopia when combined with occlusion of the fellow eye. The aim of this pilot study was to assess whether the SSRI Citalopram could be combined with standard occlusion therapy to treat amblyopia in adult humans.

Methods: A double blind, randomized, placebo controlled, cross-over design was adopted whereby placebo and Citalopram (20mg per day) were each combined with two weeks of occlusion therapy (2 hours per day). The two treatment blocks were separated by a two-week washout period and the sequence of placebo vs. Citalopram was randomized. Visual acuity (ETDRS chart), stereopsis (Randot Preschool test), pattern reversal VEPs, pattern ERG, multifocal ERG and mood (Profile of Mood States Questionnaire and DASS21) were measured before and after each of the two-week treatment blocks.

Results: Of 55 patients screened, 7 (mean age 26, range 18-49 years, 5 male) met the inclusion criteria and consented to participate. 2 participants had strabismic, 2 anisometropic and 3 mixed mechanism amblyopia. All participants had an interocular acuity difference of 0.2 LogMAR or more. Mean amblyopic eye visual acuity was 0.64 LogMAR (range 0.1 to 1.2). 5 participants reported side effects from Citalopram and 1 from placebo. The mean change in amblyopic eye visual acuity from pre to post treatment was 0.00 (range -0.03 to 0.03) LogMAR for placebo and 0.08 (range -0.06 to 0.40) LogMAR for Citalopram, a non-significant difference (p=0.2). However, 3 patients showed improvements of 0.12, 0.13 and 0.4 LogMAR for Citalopram treatment compared to 0.03, -0.03 and -0.03 LogMAR respectively for placebo treatment. No systematic effects of Citalopram were found for stereopsis, VEPs, ERGs or mood.

Conclusions: It is feasible to combine a short course of Citalopram with occlusion therapy in adults with amblyopia, however study recruitment can be challenging. The effect of Citalopram treatment on amblyopic eye VA did not differ significantly from placebo, however three patients showed VA improvements of over 0.1 LogMAR when treated with Citalopram with one patient improving by 0.4 LogMAR. Longer treatment durations may result in VA improvements in a larger number of patients.

Keywords: 417 amblyopia • 650 plasticity • 754 visual acuity