Simplified updates on the pathophysiology and recent developments in the treatment of amblyopia: A review

Amblyopia is the most common cause of monocular visual impairment affecting 2-5% of the general population. Amblyopia is a developmental cortical disorder of the visual pathway essentially due to abnormal visual stimulus, reaching the binocular cortical cells, which may be multivariate. Ganglion cells are of two types: parvocellular (P cells) and magnocellular (M cells); they are the first step where the light energy is converted in to neural impulse. P cells are involved in fine visual acuity, fine stereopsis, and color vision and M cells are involved in gross stereopsis and movement recognition. Strabismus, refractive error, cataract, and ptosis, occurring during critical period are highly amblyogenic. The critical period extends from birth to 7--8 years. The earlier the clinically significant refractive error and strabismus are detected and treated, the greater the likelihood of preventing amblyopia. Treatment for amblyopia in children includes: optical correction of significant refractive errors, patching, pharmacological treatment, and alternative therapies which include: vision therapy, binocular therapy, and liquid crystal display eyeglasses are newer treatment modalities for amblyopia. Age of starting the treatment is not predictive of outcome, instituting treatment on detection and early detection plays a role in achieving better outcomes. This review aims to give a simplified update on amblyopia, which will be of use to a clinician, in understanding the pathophysiology of the complex condition. We also share the cortical aspects of amblyopia and give recent developments in the treatment of amblyopia.

Clinical evaluation for atropine penalization in treatment of moderate and severe anisometropic amblyopia / 中华实验眼科杂志

Objective@#To evaluate the effect of atropine penalization for treatment of moderate and severe anisometropic amblyopia.@*Methods@#Retrospective cohort study was performed.Eighty moderate and severe anisometropic amblyopia pediatric patients aged 4-7 years old were enrolled from December 2011 to November 2017 in Tianjin Eye Hospital and Beijing Children's Hospital.The subjects were divided into atropine penalization group and patching group according to the treatment, with 25 cases of moderate amblyopia and 15 cases of severe amblyopia in each group.The best corrected visual acuity (BCVA) of amblyopia in atropine penalization group and patching group before treatment, 2 months, 4 months, 6 months and 8 months after treatment were compared.The binocular visual function of each group was compared before and after treatment.The compliance and complications were also recorded.This study adhered to the Declaration of Helsinki, and was approved by the Ethics Committee of Tianjin Eye Hospital (2016-42) and Beijing Children's Hospital (2019-k-33).@*Results@#There were significant differences in BVCA between the two groups before and after treatment in cases with moderate amblyopia (Fgroup=3.104, P=0.032; Ftime=4.342, P=0.013); The BCVA of atropine penalization group was better than that of patching group at 2, 4, 6 and 8 months after treatment, the differences were statistically significant (all at P<0.05). There were significant differences in BCVA between the two groups before and after treatment in cases with severe amblyopia (Fgroup=3.149, P=0.016; Ftime=5.094, P=0.024); The BCVA of atropine penalization group was better than that of patching group at 2, 4, 6 and 8 months after treatment, the differences were statistically significant (all at P<0.05). The effective rates of stereopsis reconstruction in atropine penalization group were significantly higher than those in patching group in both moderate and severe amblyopia cases, and the differences were statistically significant (both at P<0.05). The compliance rate of moderate amblyopia in atropine penalization group was 96% (24/25), which was significantly higher than 76% (19/25) in patching group, the difference was statistically significant (χ2=4.153, P=0.042). The compliance rate of severe amblyopia in atropine penalization group was 100% (15/15), which was also significantly higher than 67% (10/15) in patching group, the difference was statistically significant (χ2=6.000, P=0.014). During the follow-up period, there were 4 cases with photophobia in the atropine penalization group.No adverse reaction was observed in the patching group.@*Conclusions@#Compared with patching, atropine penalization is an effective method in treatment of moderate and severe amblyopia, with the advantage in rapid improvement of visual acuity, stereopsis recovery and compliance of treatment.Atropine penalization is worthy for clinical application.

Pharmacologic Effects of Atropine Penalization in Amblyopic Eyes

PURPOSE: To analyze the pharmacologic effect of atropine penalization in amblyopic eyes. METHODS: Distant and near visual acuity, near point of accommodation (NPA), and pupil size were measured in the sound eye of 40 children with amblyopia before and after receiving atropine sulfate 1% solution. Amblyopic children were divided into 2 groups according to the time of follow-up visit: 4-days and 7-days after injection; the same tests were performed on all the scheduled follow-up visits. This study included a control group of 20 normal children who received the same test on the initial visit and the scheduled follow-up visits. RESULTS: Visual acuity of the sound eye at distance showed greater decreases in children with 4-day follow-up visits compared with 7-day visits in the amblyopic group (p = 0.24). There was no significant difference in near visual acuity between the amblyopic group and the normal control group by follow-up interval (p = 0.98, p = 0.75). Near point of accommodation significantly increased in the 4-day visit group in both the amblyopic and the normal control groups (p = 0.04 and p = 0.03, respectively), Pupil size was significantly maintained in the 4-day visit, amblyopic group (p = 0.01). CONCLUSIONS: Atropine effectively decreased the vision of the sound eye in amblyopic children. However, to maintain the pharmacologic effect, two separate atropine instillations per week (on a weekday and the weekend) should be considered as a treatment for amblyopia.

The Prospective Comparison of the Efficacy of Intermittent Atropine Penalization and Part-time Occlusion Therapy

PURPOSE: The objective of this study was to compare prospectively the efficacy between intermittent atropine penalization and part-time occlusion therapy for amblyopia in patients younger than 10 years old. METHODS: The patients with newly diagnosed amblyopia were randomly assigned to either atropine penalization (Group A) or occlusion therapy (Group O). One drop of atropine was instilled into the sound eyes of patients in group A twice per week, while each patient in group O underwent daily patching for 6 hours in their sound eyes. The minimum follow-up time was 3 months after treatment. Best corrected visual acuity and compliance were compared for both groups. RESULTS: A total of 43 patients were enrolled in this study, with 18 assigned to group A and 25 to group O. The follow-up period was not significantly different between group A and group O (6.3 and 7.0 months, respectively; p=0.437). The final corrected visual acuity (LogMAR) scores of amblyopic eyes in both groups showed significant improvement in the visual acuity of amblyopic eyes compared with that at baseline (0.28 in group A and 0.19 in group O). Group A had a higher level of compliance than group O (97.0 and 91.5%, respectively; p=0.007). There was no difference in the groups with regard to visual acuity in amblyopic eyes,which showed similar improvement (3.5:3.4 lines, respectively; p=0.867). CONCLUSIONS: This study shows that for treating amblyopia in children younger than 10 years old, intermittent atropine penalization seems to be as effective as part-time occlusion.

The Efficacy of Intermittent Atropine Penalization in Amblyopic Children Who Have Failed Patching Therapy

PURPOSE: The purpose of this study is to assess the effect of intermittent atropine penalization (AP) in amblyopic children who have failed patching therapy. METHODS: Twenty-one amblyopic (visual acuity in the amblyopic eye >or= 0.3) children (mean age, 7.8 years) who had failed patching therapy were treated with intermittent AP consisting of one drop of atropine 1% in the sound eye, twice per week. The visual acuity was analyzed in the cases of at least 3-month follow-up after intermittent AP. Treatment success was defined as an improvement in final visual acuity of 2 lines more than baseline visual acuity in the amblyopic eye. RESULTS: The cause of amblyopia in the 21 cases was strabismus in 10 and anisometropia in 11. The mean visual acuities (logMAR) of the amblyopic eye were +0.28 before AP and +0.07 after AP. Of the 21 patients, success was achieved in 17 (84.2%), and their mean treatment duration was 7.5 months. The compliance rate with intermittent AP was 90.1%. CONCLUSIONS: Intermittent AP could be considered for amblyopic children (visual acuity in the amblyopic eye >or= 0.3) who have failed patching therapy.