RESUMO
Background The characteristics of eye movement waveforms in congenital nystagmus eyes is so complicated that the time-series waveform can hardly demonstrate the oscillational kinetic property of the eye movement of nystagmus,which is not convenient for the clinical diagnosis and evaluation.The eye movement system is a nonlinear feedback control system,and phase portrait analysis is a useful method in describing the characteristics of movement in a nonlinear system.Objective This study was to establish the phase portrait analysis method of the eye movement waveforms in congenital nystagmus eyes and provide a new technique for the clinical diagnosis and evaluation of congenital nystagmus.Methods A prospective series-case observational study was performed.This study complied with the Declaration of Helsinki and was approved by Ethic Commission of Tianjin Eye Hospital.Written informed consent was obtained from each patient before examination.Twenty-five patients with congenital nystagmus were enrolled and received examination of video-oculography (VOG) in Tianjin Eye Hospital from April 2012 to February 2013,including 12 patients with congenital motor nystagmus (CMN) and 13 patients with latent nystagmus (LN).The VOG data were format-converted and processed by a Matlab routine.VOG-based phase portraits of eye movement cycles were drawn and related parameters were measured from the phase portraits for further analysis and comparison.Main measurement indexes were cycle position shift (CPS),slow phase peak velocity (SPV),standardized slow-phase peak (SSPV),fast phase peak velocity (FPV) and standardized fast-phase peak velocity (SFPV).Two principal types of waveforms,increasing-velocity type and decreasing-velocity type were compared.Results The phase portraits of the waveforms of congenital nystagmus were cycles of reciprocating trajectories.The slow phases were in dense ribbon region,and the fast phases were in sparse annular region,and all the trajectories travelled in clockwise.The CPS,SPV and FPV of increasing-velocity type were (4.646 ± 1.565),(223.821 ± 114.049),(767.481 ±263.560) ° per second,respectively.The CPS,SPV and FPV of decreasing-velocity type were (9.373 ±4.189),(357.531 ± 154.300) and (1 148.706 ±541.362) ° per second,respectively.The SPVs and FPVs of both increasing-velocity type and decreasing-velocity type showed strong correlation with CPS,respectively (the increasing-velocity type:rSPV-CPS =0.685,P=0.000;rFPV-CPS =0.680,P=0.000;the decreasing-velocity type rSPV-CPS =0.783,P =0.000;rFPV-CPS =0.803,P =0.000).FPVs were significantly larger than SPVs in both types of waveforms (t =6.558,P =0.000;t =5.068,P =0.000).The SSPV of increasing-velocity type was (48.062 ± 15.365) ° per second,which was slightly larger than (41.099± 17.027) ° per second of decreasing-velocity type,with no significant difference between them (t=1.070,P=0.296).The SFPV of increasing-velocity type was (171.186±47.825)° per second,which was larger than (125.317-±38.266)° per second of decreasing-velocity type,showing a significant difference between them (t =2.658,P =0.014).Conclusions Phase portraits can visualize the cyclically dynamic features of congenital nystagmus in a direct way.It facilitates the measurement of eye movement amplitude,speed and other parameters.The phase portrait analysis method provides a novel useful tool in the clinical diagnosis and treatment efficacy evaluation of congenital nystagmus.
RESUMO
Background Congenital nystagmus is a common disease threatening visual function.The clinical description of congenital nystagmus is still not enough now. Objective The aim of this study was to report the motor and sensory characteristics of congenital nystagmus. Methods A retrospective clinical case analysis was designed.The clinical data of 376 patients with congenital nystagmus were collected.These patients were diagnosed in Henan Eye Institute from January,2005 to August,2011.The clinical characteristics of patients,including age,pedigree analysis,nystagmus classification,ocular alignment,visual acuity,refractive error,stereoacuity and oscillopia,was summarized.Informed consent from all patients and custodian were obtained. Results The age distribution of most patients was ＞5-10 years and ＞ 15-20 years,with the percentage 24.73％ and 24.20％,respectively.Of 376 patients,sensory defect nystagmus was 172 cases,and that of motor sensory defect was 204 cases.The most common inheritance pattern was autosomal dominant.Conjugate uniplanar horizontal oscillations were found in 73.94％patients,and strabismus was found in 66.36％ in this study.Sensory defected subjects did not show a statistically significantly higher strabismus incidence when compared with the idiopaths (x2 =3.048,P =0.081 ).The binocular distance vision in all the subjects was declined in comparison with normal eyes,the best corrected vision was 0.27 ±0.11 and 0.50± 0.13 in sensory defected nystagmus and idiopaths nystagmus respectively,showing a significant difference( t =16.495,P =0.000 ).The incidence of refractive error in this study was 77.62％.Incidence of astigmatism(75.17％ ) was higher than that of myopia and hyperopia ( 39.03％ and 36.12％ ).No significant difference was seen in refractive error incidence between the sensory defected and the idiopaths (x2 =1.337,P =0.248).Patients of 65.18％ displayed non-stereoacuity or very gross acuity levels (3000) in this study,and the patients with idiopathic nystagmus showed better stereoacuity level in comparison with sensory defected ones (x2 =7.058,P =0.008 ).Five of 313 patients existed experienced oscilopla under binocular viewing conditions.Conclusions Autosomal dominant inheritance is the most common pattern of congenital nystagmus.Conjugate uniplanar horizontal oscillation is thought to be a common type of nystagmus.Incidence of strabismus is higher,and visual acuity and stereoaeuity are worse in congenital nystagmus than in common population.Oscillopia is seldom found in congenital nystagmus.
RESUMO
Congenital idiopathic nystagmus (CIN) is characterized by monoocular or biocular involuntary,rhythmical,repeated oscillations.CIN is often referred to congenital 'motor' nystagmus since nystagmus occurs in the absence of a clinically demonstrable defect in the visual sensory system.CIN is genetically heterogeneous,and patterns of its inheritance have been well-known to include autosomal dominant.autosomal recessive and X-linked patterns.In recent years, many different genetic loci for CIN have been mapped,and researchers have found some candidate causing-disease genes.This review focuses on the recent advances of gene mapping and candidate gene analysis for molecular research of CIN.
RESUMO
Background The surgery for congenital idiopathic nystagmus has make great progression recent year,but the influence of surgery on visual function is closely concerned.Objective This work was to study the surgeries for congenital idiopathic nystagmus with or without strabismus and explore the effect of horizontal rectus muscle surgery on the visual function and ocular movement in congenital idiopathic nystagmus.Methods This was a case-observational study.Sixty cases with idiopathic congenital nystagmus were enrolled assigned to four groups as follows:The patients of group Ⅰ appeared the head postures of less than 15 ° and heterotropia less than 15△underwent extraocular proprioceptiou resection,and those of group Ⅱ presented with the head postures of less than 20° and heterotropia more than 15△ underwent extraocular proprioception resection and stabismus surgery.In the group Ⅲ,the patients had the head postures of more than 15° and heterotropia less than 15△ underwent Park's surgery and part of them underwent extraocular proprioception resection) and the cases in group Ⅳ were selected with the head postures of more than15° and heterotropia more than 15△ underwent Park' s surgery and strabismus surgery ( part of them underwent extraocular proprioception resection).Baseline and follow-up evaluations included the best distance and near corrected visual acuity,head posture,ocular movement and Titmus stereotest.The examination results were compared between before and after operation.Results One year after operation,monocular and binocular distance visual acuity improved significantly in all four groups ( monocular:t =6.00,8.94,11.76,16.41,P =0.00 ; binocular:t=4.81,P=0.01 ; t =6.27,4.25,4.18,P =0.00 ),but monocular and binocular near visual acuity improved significantly only in groups Ⅲ and Ⅳ after operation compared with before operation ( monocular:t=2.91,P=0.01 ; t =5.32,P =0.00 ; binocular:t =3.36,t =4.30,P =0.00 ).The compensatory head posture from 39 subjects was disappeared after operation,showing an evident difference between before and after surgery ( group Ⅲ:t =29.90,P=0.00;group Ⅳ:t=16.91,P=0.00).Strabismus were corrected rightly for 24 patients and undercorrection for 2 patients.( group Ⅱ:t =29.15,P =0.00 ; group Ⅳ:t =36.79,P =0.00 ).The binocular visual function of 23 cases with the age below 12 years were improved throughout the follow up duration ( t =12.06,P =0.00).Conclusions Park' s surgery,extraocular proprioception resection and strabismus corrective operation can improve the visual function and head posture in congenital idiopathic nystagmus patients.