The Effect Of Occlusion Therapy On The Efficacy And Refractive Changes In Amblyopic Children

Among a lot of conventional amblyopia therapy, occlusion therapy is one ofthe most important and cost-effective, widely accepted and preferred method oftreatment. Initially, the main treatment is full-time occlusion therapy, which canmake rapid increase in visual acuity of amblyopic eyes, and consolidationtherapy using a short-time occlusion. But in the long-term clinical practice, thereare many factors to affect the enough dose of the full-time occlusion that canreduced the compliance of patients,dose and efficacy of full-time occlusion, orlead to complications by the poor guide. At present, in the initial treatment,choose the part-time occlusion is almost common, not only improves thedependence, but also for good efficacy. Moreover,the treatment effect of thepart-time occlusion has been confirmed in clinical research and practice, but theclinical use different ways of occlusion treatment and have many details in thechoice of the dose. Therefore, the dose of occlusion is no uniform standard thatis depending on the doctor's personal experience, for instance, as short as only1-hour occlusion or long to 24-hour daily.Objective:The purpose of this study was to investigate the effect of occlusion therapy on the efficacy and refractive changes in amblyopic children and analyze how tochoice the personalized dose of occlusion and related issues during the treatment.The relationship of the efficacy of part-time(2h/d, 6h/d)occlusion treatmentversus full-time occlusion for different levels(light, moderate, severe),differentfactors (amblyopia associated with strabismus, anisometropia, both strabismusand anisometropia, ametropic amblyopia) of amblyopia in children aged 3-13years were evaluated. In the cured eyes with amblyopia, the process ofemmetropization in amblyopic children with spectacles or combined withpatching was also analyzed.MethodsMethods:1. Patients selection: 135 children (153 of amblyopic eyes: 117 of unilateralamblyopia and 18 of binocular amblyopia with 2-lines BCVA difference)between 3-13 years of age with a confirmed diagnosis of strabismic amblyopia(42 cases), anisometropic amblyopia (40 cases), both strabismus andanisometropia (6 eyes), ametropic amblyopia (47 cases) were selected from thedifferent three hospitals in Xi'an. In addition, all patients were further devidedby the level with mild (42 cases), moderate (53 cases) and severe (40 cases), theage groups with 3~6 years old (77 cases), 7~10 years old (46 cases) and >10years old (12 cases).2. Main outcome measurements: The testing protocol included visual acuity(Snellen chart), BCVA (the best corrected visual acuity), ocular motility examination,binocular vision,fixation, cycloplegic refraction (1% atropine sulfateand retinoscopy) and ocular examinations. Cases were followed every 1 monthor 2 months, and measured the refraction each year cycloplegiccally. ,3. Treatment:(1) With spectacle for the BCVA. (2) Occlusion therapy: fellow eye with part-time(2h/d,6h/d)and full-time patching regimens, respectively. (3)The sound eyes performed 1 hour of near visual activities homely in all patchinggroups. (4) Follow-up: Protocal-specified follow-up visits were conducted atevery 1 or 2 months. At baseline and each protocol- specified visit, visual acuity,BCVA, stereo and binocular vision (Titmus stereo acuity) were measured.4. Statistical methods: At the point on curing of amblyopic eyes, the efficacy ofdifferent patching regimens (2h/d, 6h/d and full-time) were determined by visualacuity and Titmus stereo acuity compared with the changes of sound eyes. Thevisual acuity distances from baseline to every visit were considered as"statistical value of visual acuity"calculated by formula"Euclidean Distance"(d=√[(x1-x2)2+ (y1-y2)2]). The refractive changes in sound eyes and felloweyes of amblyopic children treated with different occlusion protocols wereanalyzed. The all data were statiscal analyzed by using SPSS 17.0 statisticalsoftware.ResultsResults:Part I: The analysis on efficacy of different occlusion groups1. Effect of treatment on visual acuity in the cured eyes with amblyopiaSubstantial improvement in visual acuity from baseline to every visit occurredin different patching groups. The average visual acuity had improved frombaseline by an average of of 0.19±0.06 (Snellen chart) every visit in amblyopiceyes of each group. The average improvement in visual acuity in full-timepathing group was higher than that of patching with 6 hours of daily(P=0.001).The visual acuity improvement appeared to be similar among full-time group , 2hours of daily patching and 6 hours patching of daily(P>0.05). The averageimprovement in visual acuity of cured amblyopic eyes in 6 hours of dailypatching was lower than that of the groups with 2 hours and full-time of daily patching(0.908±0.129,P=0.009). There was no statistical difference for animprovement of visual acuity between 2 hours and full-time of daily patchinggroups(P>0.05).At the cured visit, visual acuity had improved from baseline by an average of4.92±1.421 lines, 5.62±1.858 lines and 6.60±1.917 lines in 2-hour, 6-hour andfull-time of daily patching groups, respectively(P<0.05). The improvement invisual acuity of sound eyes from baseline in the full-time of daily patchinggroup was better than that of the other two groups in children aged 3 to 6 yearsold(6.82±2.098 lines,P=0.003), but in the 2 hours of daily patching group wasbetter than that of the other two groups in children aged 6 to 10 years old(4.45±0.934 lines,P=0.008). The magnitude of visual acuity improvement ofsound eyes, which were given full-time patching in anesometropic amblyopia(7.11±1.595 lines,P=0.001)and 6-hour patching in ametropic amblyopia(7.00±1.852 lines,P=0.02), were better than that of others..There were significant differences of treatment period among groups indifferent patching regimens at the cured time point (2-hour patching: 8.49±6.365mo, 6-hour patching: 10.62±6.938 mo, and full-time patching: 18.64±16.317mo). The treatment period of full-time patching in strabismic amblyopic groupwas longer than that of the other groups (28.28±11.923 mo,P=0.001).The lines of visual acuity improvement in first visit were named"first-doseeffect". There were no significant differences among different patchingprotocols, different causes and different ages in"first-dose effect"of visualacuity improvement(P>0.05), except that ametropic amblyopia with 6-hourpatching was more than that of the strabismic and anisometropic groups(2.13±0.835 lines,P=0.011).2. Effect of treatment on stereo acuity in the cured eyes with amblyopia There were significant improvement between 2 hours of daily patching andthe other patching groups in the percentage of patients whose stereo acuity wasimproved from baseline at the cured visit (2-hour patching: 25.8%, 6-hourpatching: 9.1% and full-time patching: 15.2%).3. Changes of"statistical visual acuity value"in different patching protocols byusing "Euclidean Distance" formula.Using of the "Euclidean Distance" formula (d=√[(x1-x2)2+(y1-y2)2]), we triedto calculate the visual acuity distances of both eyes from baseline to every visit.The distances were named"statistical visual acuity value". The more statisticalvisual acuity value was, the more efficient of amblyopic treatment was. Thestatistical visual acuity values of different patching regimens were decreasingduring the treatment. Initially, the average statistical visual acuity value offull-time patching groups was less than that of the other patching groups withdifferent ages and causes(strabimic group: 0.60±0.242,P=0.027; anisometropicgroup: 0.69±0.245,P=0.0016; 3 to 6 years old group: 0.53±0.267,P=0.001).Otherwise, there were similar values among the three patching groups at thecured visit(P>0.05).Totally, the visual acuity improved rapidly in the full-timepatching group(P<0.05). There was similar between 2 hours and 6 hours ofdaily patching groups(P>0.05). According to the changes of statistical visualacuity values, there were significant differences among different patchingprotocol groups in different ages and causes but not in the different levels ofamblyopia (3 to 6 years old: 0.77±0.236,P=0.001; strabimic group: 0.67±0.16,P=0.027; anismetropic group: 0.737±0.298,P=0.016).PartⅡ: Refractive changes in amblyopic children with treatment ofspectacle and patchingIn monocular amblyopic group: the cured age of amblyopic eyes was 8.34±2.15 years, an average annual reduction of spherical power was0.46±0.42DS and cylindrical power of -0.056±0.24DC; An average annualreduction of spherical power in fellow eyes was of 0.28±0.62DS and cylindricalpower of 0.003±0.067DC. In binocular amblyopic group: the cured age was9.67±2.34 years, an average annual reduction of spherical power of0.40±0.32DS, reduction of cylindrical power of 0.016±0.14DC. There were nosignificant statistical differences (P>0.05) between spherical and cylindricalchanges among all groups, but the significantly statistically differences (P<0.05)in the annual changes of spherical equivalent were noted between the felloweyes and other two groups. There were positive correlations (r=1.000) betweenage of the first diagnosis and the average annual change of spherical andcylindrical errors, and the peroid of treatment.ConclusionConclusion:1. When combined with 1 hour near visual activities, 2 hours and 6 hours ofdaily patching produce the improvement in visual acuity that are of similarmagnitude to the improvement produced by full-time of daily patching intreating different levels and different causes amblyopia in children aged 3 to 13years old.2. The 6 hours of daily patching produces the most improvement in visual acuitywith"first-dose response"in ametropic amblyopia.3. The total-improved-lines are not refer to the efficacy of amblyopic treatmentobjectively unless combined with other factors such as the first-improved-linesor total course of treatment and so on.4. The 2 hours and 6 hours of daily patching groups produce the shorter totalcourses of treatment vesus full-time occlusion group. The outcome shows thatthe treatment course of 2 hours of daily patching is the shortest. 5. Stereo acuity improvement is related to the level of amblyopia. The 2 hours ofdaily patching is observed the best improvement of stereo acuity.6. Using of the "Euclidean Distance" formula (d=√[(x1-x2)2+ (y1-y2)2]) tocalculate the visual acuity distances from baseline to every visit, this methodcould avoid bias of amblyopic children themselves subjectively, suggesting toextend its application in the evaluation of vision improvement in amblyopiatreatment.7. Spectacles combined with patching may decrease the process of emmetropizationin fellow eyes but not in sound eyes. There are no remarkable effects bypatching on amblyopic eyes with monocular or binocular amblyopia.InnovationsInnovations:1. This is the first time to determine the improvement of visual acuity withdifferent treatment protocols at the first visit by using"first-dose effect". It is anew way to show the dose-efficacy relationship with the different patchingregimens.2. This is the first report to establish a new evaluation method by using"Euclidean-distance"formula to calculate the improvement of visual acuitythroughout the occlusion treatment of amblyopia.