Prismatic Correction Research Articles

A Preliminary Study on the Outcome of Plication Augmentation of the Augmented Anderson Procedure for Patients with Infantile Nystagmus Syndrome and a Face Turn.

Purpose:To report the results of plication augmentation of the augmented Anderson procedure in patients with infantile nystagmus syndrome and face turn.Methods:In this retrospective study, all patients who underwent plication augmentation of the augmented Anderson procedure between August 2015 and November 2018 were included. Our study included patients older than 6 years with a face turn >25°. We also included patients with residual face turns ≥15° after Anderson-type procedures. The face turn was measured by a goniometer and also quantified with prisms placed with apex in the direction of the face turn. We plicated the medial rectus of one eye by 5.0 mm and lateral rectus of the fellow eye by 7.0 mm based on the direction of the face turn in addition to the augmented Anderson procedure. Patients were reviewed on the 1st postoperative day, 1st month, and every 6 months thereafter.Results:Eight patients with a mean face turn of 27.5° ± 6.5° underwent plication augmentation of the augmented Anderson procedure. Two patients had residual face turns after a previous Anderson-type procedure. We obtained a mean correction of 25° ± 6.5° with a median prismatic correction of 45 prism diopters (PD) for each eye. The median face turn at the last review was 2.5°, and all patients were corrected to within 10°. Excluding patients operated for residual face turns, we had a mean dose response of 2.7 PD/mm and 1.7°/mm of surgery on each eye. Five patients had an improvement in null zone visual acuity. Two patients had a restriction in ocular motility of −2 in the direction of the recessed extraocular muscle at the last review, and the remaining had a −1 restriction.Conclusions:Plication augmentation of the augmentation Anderson procedure appears to be a safe and effective procedure for patients with infantile nystagmus syndrome and a face turn more than 25°. It may also be used for residual face turns more than 15°.

Призматический этап лечения пациентов при остро приобретенной эзотропии с диплопией

Purpose. To analyze changes in binocular vision functions in patients with acutely acquired esotropia after preoperative correction by prisms. Material and methods. The study included 10 patients with acutely acquired esotropia with diplopia. Depending on the tactics of preoperative case management, two groups were distinguished: 1 - 5 patients, this group underwent preoperative prismatic correction of diplopia and the deviation angle, 2 - 5 patients, in this group underwent surgery without prior prismatic correction. Fresnel prisms were used to select and assign prismatic correction. The patients were monitored dynamically. Results. In the course of treatment 1 group according to the indicator of Worth's four-dot test color test, revealed a statistically significant increase in the frequency of value of the binocular single vision (p=0.041), the frequency of the presence of stereovision according to the Fly-test (p=0.013). Conclusion. Prismatic correction in combination with surgical treatment had better curative benefits than surgery itself in improving binocular and stereoscopic visual functions. Key words: acutely acquired esotropia, binocular vision, Fresnel prisms.

Экзофория: клиника, диагностика, лечение. Современный взгляд на проблему. Обзор литературы

Purpose. Create a summary classification of exophoria. To propose an optimal algorithm for optometric and surgical methods of treatment. A modern view of the problem. It is optimal to subdivide exophoria according to the state of the vergent-duction balance into divergence excess, basic exophoria, convergence insufficiency, divergence pseudo-excess, lateral gaze incomitance. By the degree of compensation for compensated, subcompensated, uncompensated, decompensated. In combination with alphabetic pattern for exophoria without pattern, exophoria in combination with horizontal type A pattern, exophoria in combination with vertical type A pattern, exophoria in combination with horizontal type V pattern, exophoria in combination with vertical type V pattern. Features of optimal optical and prismatic correction depend on the state of the vergent-duction balance. In cases of exophoria without pattern surgical treatment is carried out during the transition from a state of subcompensation to non-compensation. In case of exophoria with horizontal-type alphabetical pattern, combined horizontal-transpositional surgery is optimal: elimination of exophoria, the protocol is based on the amount of deviation in the direct gaze position; elimination of the pattern, the protocol is based on vertical transposition of muscles of horizontal action. In cases of exophoria with vertical-type pattern, it is necessary to perform staged vertical-horizontal surgery: stage 1 – elimination of vertical heterotropy in adduction; stage 2 – elimination of exophoria (the protocol is based on the amount of deviation in the direct gaze position). Conclusions. The treatment protocol should be based on a reliably diagnosed diagnosis and consists at the pre-surgical stage in the optimal optical and prismatic correction, the appointment of orthopto-diplopto-prismatic treatment. The effectiveness of treatment is assessed by the dynamics of the disease: the magnitude of exodeviation and the stage of compensation. The protocol of surgical treatment must be reasonable and timely. Key words: exophoria, divergence excess, convergence insufficiency, basic exotropia, lateral gaze incomitance, alphabet pattern.

Exercise-induced diplopia: a mysterious and rare entity

ABSTRACT A rare case of idiopathic exercise-induced diplopia was reported. A 28-year-old male experienced diplopia during and after intensive exercise. These symptoms had been present for over a year. Upon first examination, orthophoria was found. Upon examination after intensive exercise, an esophoria of 10∆ at near and an esotropia of 4∆ at distance was found. Neuroimaging and neurological, cardiological, and hematological evaluations were normal. A prism correction, to be used during exercise, partially resolved the diplopia. This case report aims to highlight and create general awareness about exercise-induced diplopia.

Efficacy of visual process improvement in patients with homonymous hemianopia

Homonymous hemianopia is a visual field defect following a stroke, tumor development, traumatic brain injury and other rare causes. Due to the damage to the visual system, lateral neglect occurs that induces difficulties with detecting objects on one side of the binocular visual field, which exposes patients to potential danger during daily activities, especially performed outside – in traffic. Different optical aids such as Fresnel prism have been developed to help those patients by increasing the perception of the affected hemifield. This prism correction can appear in various configurations, for instance: yoked prism, monocular and binocular sector prisms placed with a base to the affected side. The other option to deal with these patients is visual training based on stimulating the affected hemifield.

Intermittent exotropia ‒ follow up and control

Intermittent exotropia is the most common form of exotropia. According to clinical studies the frequency of this type of horizontal strabismus increases. The article covers current approaches of follow up and control of intermittent exotropia. It summarizes the conservative treatment (optical, prism correction, occlusion) and the surgical option from the literature. This is compared with the author’s personal experience.

Нистагм у детей: что нужно знать педиатру

Despite its low prevalence, nystagmus occupies a special position among the variety of ophthalmopathology in children. The disease affects visual functions, causes difficulties in treatment, becomes the cause of the patient’s psychological and social discomfort and professional limitations, and requires rehabilitation measures. The review presents literature data on the nystagmus classification and pathogenesis. However, to date, the neural mechanisms underlying this pathology have not been fully studied. Many hypotheses have been proposed, which come down to disturbances in the oculomotor centers as the direct cause of nystagmus. The role of the oculomotor muscles in the onset of the disease has not received proper study. The article focuses more on the manifestations of infant nystagmus, which is found in the first 3–6 months of a child’s life. Children’s nystagmus may be idiopathic, associated with other eye conditions, albinism, or by a part of neurological syndromes or diseases. The combined pathology requires the participation of not only an ophthalmologist, but also a pediatrician, neurologist, geneticist and doctors of other specialties in the diagnostic examination and treatment. The article describes methods of treating nystagmus aimed at reducing its amplitude and increasing visual acuity. The surgical methods include recession, resection, or tenotomy of the horizontal ocular muscles. The pharmacological methods consist in the use of antiglutaminergic drugs, an agonist of gamma-aminobutyric acid and an inhibitor of carbonic anhydrase, but the mechanism of their effect on nystagmus is not fully understood. The optical methods are represented by the selection of soft contact lenses or glasses for ametropia, as well as prismatic correction. Unfortunately, there are no effective ways to eliminate nystagmus.

Stereopsis deficiency treatment using virtual reality games in exotropic candidate for firefighter

Background: Impaired stereopsis very often limits career options for patients with binocular vision disorders. Eyesight requirements for some occupations like police officers and firefighters usually include perfect visual acuity. In Poland, candidates for these professions must also demonstrate perfect stereopsis. The presented case study aims to demonstrate that vision therapy (VT1) mixed with new technologies may be an effective treatment for young adults who do not meet the chosen occupation's visual requirements.
 Case report: A case of a young man diagnosed with intermittent exotropia and poor stereopsis is discussed. Poor stereopsis did not allow him to pass the ophthalmological qualification tests to the fire academy. Vision therapy was implemented to improve stereopsis. The case report presents the patient’s treatment implemented within 4 years. The patient started with prismatic correction, then received the office-based VT with home reinforcement. The improvement in fusional vergence and the control of deviation was observed. Nevertheless, the patient was still stereo-deficient. 3 years later, Binocular Vision Therapy in Virtual Reality (BVTVR2) was recommended. The patient received home-based therapy for 16 weeks (60 minutes per day), which has resulted in significant improvement of stereopsis. As a result, he finally met the visual requirements to become a firefighter.
 Conclusion: BVTVR appears to be a promising rehabilitation method for patients with poor stereopsis. Three-dimensional anti-suppression therapy and dynamic, real-life stereopsis training seem to be a more effective treatment of poor stereopsis compared to standard VT techniques.

Еvaluation of Stereo Vision Based on Chromostereopsis in Patients with Strabismus

The study is devoted to one of actual problems of modern strabismological — the development of effective methods for evaluation of stereo vision. The purpose: to develop an effective method for evaluating stereopsis based on chromostereopsis (CS) in patients with strabismus. Patients and methods . We observed 135 children aged from 8 to 17 years, who were divided into three groups, equivalent age: 1) 45 children with ametropia; 2) 31 children with not paralytic strabismus; 3) 59 children — the control group without ophthalmopathology. At the first stage, we investigated the possibility of using “ChromaDepth glasses” for qualitative assessment of stereo vision in three groups of children. We used three types of stimuli: a modified Kanisza shape; test images that create an illusory square shape; a color version of the Poggendorff shape. At the second stage, we investigated the possibility of using images with different spectral characteristics and prisms for qualitative and quantitative evaluation of stereovision based on CS in the same three groups of children. Results. The analysis of the results obtained at the first stage showed high sensitivity (90.6 % for the 1st stimulus, 90.5 % for the 2nd and 99 % for the 3rd) and specificity (96.5 % for the 1st stimulus, 93.3 % for the 2nd and 84.4 % for the 3rd) for all three stimuli used for qualitative evaluation of stereo vision. At the second stage, we obtained results demonstrating an increase in the severity of CS with an increase in the strength of prisms in control children and children with ametropia, as well as results indicating the effectiveness of the developed method for evaluating stereovision in children with a strabismus angle. Conclusion. The method of studying CS with the help of “ChromaDepth glasses” is a simple and effective method of qualitative assessment of stereovision. The developed method of qualitative and quantitative assessment of stereovision based on CS using stimuli with different spectral characteristics and prisms allows us to assess effectively the state of stereovision. It doesn’t required additional separation of the visual fields even if there is a strabismus angle (using its prismatic compensation) and predict the possibility of occurrence and severity of undesirable chromatic illusions in patients when prescribing prismatic correction.

Combined passive and active treatment in strabismic amblyopia with accommodative component

BackgroundTreatment of amblyopia in esotropic subjects with accommodative component currently consists of optical correction and subsequent occlusion, or penalisation, of the dominant eye. This treatment obtains a good outcome in visual acuity but poor outcomes in binocular vision. An intervention protocol that could improve the outcome of conventional treatment is presented.MethodsA retrospective study in subjects with amblyopia associated with both fully accommodative and partially accommodative esotropia is presented. Subjects were refracted under cycloplegia and treated with occlusion (passive therapy). Subjects who did not achieve orthotropia through optical correction (partially accommodative esotropia) performed an active therapy (full‐time prismatic correction and subsequent fusional vergence therapy or surgery in larger angles > 12 prism dioptres). After treatment, the subjects were examined by a masked optometrist in an external ophthalmology clinic.ResultsTwenty‐six subjects (12 males and 14 females) aged from six to 13-years (median 8.50; interquartile range [IQR] 3) were included. Median age of detection was three years (IQR 1). All the subjects were hyperopic. In the baseline, median best‐corrected visual acuity of the amblyopic eye was 0.40 logMAR (IQR 0.30) and 0.00 logMAR (IQR 0.01) in the dominant eye. After the treatment, the median best‐corrected visual acuity in the amblyopic eye was 0.06 logMAR (IQR 0.08). These differences were statistically significant (p < 0.001). All subjects acquired stereoacuity equal or better than 800′′ with the Randot Preschool Stereoacuity Test.ConclusionsThe proposed treatment highlights the management of amblyopia in esotropic subjects with accommodative component. This intervention protocol could help to determine if the treatment has to be passive (in fully accommodative esotropia) or a combination of passive and active therapies (in partially accommodative esotropia).

Long-term surgical outcomes of preoperative prism adaptation in patients with partially accommodative esotropia.

To determine the long-term surgical outcomes of preoperative prism adaptation test (PAT) in patients with partially accommodative esotropia. PAT was performed for the remaining esotropia after full correction of hyperopia. Prism adaptation (PA) responders were defined as patients with stable esodeviation between 0 and 8 prism diopters (PD) while developing sensory fusion throughout the prism adaptation period. Surgical success was defined as a deviation within 8 PD of both the far and near deviation angles at the last follow-up examination. Of the 102 patients, 43 (42.2%) were PA responders, and 59 were PA non-responders (57.8%). After a mean follow-up duration of 6 years after surgery, the surgical success rate was significantly higher in PA responders (76.7% vs. 54.2%, p = 0.023). By multivariate analysis, good stereoacuity at near before surgery significantly correlated with successful outcomes after surgery (p = 0.001, β = 4.466). The risk factors of undercorrection were preoperative esotropia >35 PD (OR 3.067, p = 0.041), and preoperative hyperopia >+5.25 diopters (OR 3.099, p = 0.049). Among undercorrected patients, the annual decrease of esodeviation was significantly greater in PA responders (p = 0.043). PA responders showed a better long-term success rate than in PA nonresponders. Patients with high hyperopia and large esotropia had a higher risk of undercorrection. Undercorrected patients eventually achieved good motor outcome with postoperative prism correction if they were PA responders before surgery.

Prism treatment of acute acquired concomitant esotropia precipitated by visual confusion

ABSTRACT Objective Acute acquired concomitant esotropia (AACE) is a distinct subtype of esotropia. The purpose of this retrospective study was to describe the clinical characteristics and discuss the diagnostic and therapeutic management, and evaluate the effect of prism treatment. Methods The records of 30 patients who presented with acute-onset diplopia at the General Hospital of Central Theater Command from August 2015 to November 2018 were reviewed. All patients underwent a complete medical history, ophthalmological and orthoptic examinations, and brain and orbital imaging. The patients were followed up between 2 and 8 months (mean 3.9 ± 1.2). Angle of strabismus, refractive error, stereopsis, and results of treatment with prisms were analyzed. Level of stereopsis was assessed before and after prismatic correction. Patient satisfaction was assessed with a telephone follow-up survey. Results The mean age of the 30 patients was 29.7 ± 10.3 years (range 14–52). All patients complained about uncrossed diplopia, only at distance. The esophoria was concomitant in all cases ranging from 12 to 60 prism diopters (PD) at distance (mean 35.80 ± 14.17) and from 10 to 46 PD at near (mean 26.23 ± 11.46) (t = 6.51, P <.001). Cycloplegic spherical-equivalent refraction averaged −5.25 ± 1.67 D (range −0.50 to −8.13), 28 patients were myopic and 2 were emmetropic, all did not wear glasses for near work. All patients received brain and orbital computed tomography scans and magnetic resonance imaging and, in some cases, neurological examinations were performed. All of these examinations were normal. In 27 out of 30 patients treated with prisms, the diplopia resolved, whereas three patients were not satisfied with prismatic correction and underwent surgery. With prisms the esophoria was concomitant, ranging from 6 to 23 PD at distance fixation and from 4 to 18 PD at near fixation. Out of 30 patients, 23 patients were satisfied, 3 patients were not satisfied because their vision remained uncomfortable and 4 patients had an intermediate score. Conclusion AACE was characterized by a sudden onset of concomitant non-accommodative esotropia with diplopia or visual confusion. In most cases, prismatic correction had a favorable effect with a resolution of diplopia. It offers a good treatment alternative in the early stage, when the angle of strabismus is unstable and surgery is not without risk.

Strabismus and oculomotor disorders induced by injection anesthesia for cataract surgery

To analyze diagnostic and treatment outcomes in patients with strabismus and oculomotor disorders induced by injection anesthesia for cataract surgery. The study included 11 patients (7 women and 4 men) aged 61 to 85 years (the mean age of 66±7.1 years) who complained of diplopia in the early post-op period after cataract phacoemulsification and elastic IOL implantation under retrobulbar anesthesia. Prior to further surgical treatment, all of the patients underwent functional multispiral computer tomography of the orbits. Prismatic spectacle correction was also used independently or in addition to surgical treatment. Eight out of eleven patients underwent one- or two-step surgical treatment (3 and 5 cases, respectively). In 2 patients, hypotropia did not exceed 10 prism diopters, and thus, diplopia could be compensated with prismatic spectacle correction alone. In 5 cases, binocular vision was achieved throughout the whole field of gaze. In 3 cases, surgical treatment enabled elimination of heterotropia in the primary gaze and compensation of diplopia within a radius of 40º from the center of gaze and within the entire horizontal range of eye-movement in the downward gaze. The limitation of ocular mobility decreased from 2.36 to 0.55 points leading to an associated decrease in the area of binocular diplopia - from 98% to 29%. In one case, spectacle occlusion was used. The inferior rectus restriction is the morphological substrate of anatomical and functional changes induced by retrobulbar anesthesia. As treatment options for restrictive vertical strabismus and binocular diplopia, both surgical (extraocular muscle surgery) and optical (prismatic correction, occlusion) methods should be considered.

Non-surgical correction of diplopia after stroke- a strong impact factor on quality of life-minireview

One of the most frequent disorders accompanied by diplopia is represented by stroke. Beyond different symptoms of stroke, diplopia constitutes an important clinical factor in influencing the quality of life in surviving patients. In this paper we discuss the visual impairment associated with stroke location, types of diplopia, the clinical examination, and the nonsurgical treatment of diplopia. The purpose of diplopia treatment is to restore binocular vision and eliminate the double vision. The most used nonsurgical treatment for diplopia is the optical correction by the prisms. Another therapeutic option is the botulinum toxin injections. Key words: diplopia, stroke, visual rehabilitation, prism correction,

Long-term outcomes of prismatic correction in partially accommodative esotropia.

In partially accommodative esotropia (PAET), prism glasses can correct small angles of residual esotropia but the long-term effect of prismatic correction alone without surgery has not been reported. We aimed to investigate the long-term outcome of prism glasses after full hypermetropic correction for PAET. This retrospective, case-control study was performed for children aged 10 years or younger with a residual esotropia of ≤ 20 prism diopters (PD) after full hypermetropic correction who were fitted with prism glasses and followed-up for 3 years or more. Clinical characteristics and the angle of esodeviation were obtained at each follow-up examination. Successful motor outcome after 3 years of prismatic correction was determined if the residual angle of esotropia after full hypermetropic correction was ≤ 10PD. Patients who eventually weaned off prism glasses were noted. Among 124 patients, 30.6% achieved success and 7.3% weaned off prism glasses after 3 years of prism-wear. Smaller amount of latent esodeviation (P = 0.001) revealed by prism adaptation and good fusional response at near with the Worth 4-dot test were significant prognostic factors of success by multivariate analysis (P = 0.033). After 3 years of wearing prism glasses, the rate of improvement in stereoacuity was higher in the Success group (60.5% vs 27.9%) (P = 0.001), however, there was no significant difference between the prism-weaned group and prism-wearing group within the Success group (P>0.05). Prism glasses for small angle PAET can be a treatment option in patients who have a small angle of latent esodeviation revealed by prism adaptation and good sensory fusion at near. Otherwise, early surgery may be advisable as the majority of patients showed suboptimal outcome even after long-term prism-wear.

Etiologies and treatment of manifest vertical deviations: series of 95 patients

AbstractPurposeManifest vertical deviations (MVD) are permanent vertical misalignment of one or both eyes. A hypertropia is a form of vertical strabismus where one eye is deviated upwards in comparison to the fellow eye, as opposed to hypotropia, where one eye is deviated downwards. The aim of this study is to analyze the different etiologies associated with MVD and their management.MethodsA retrospective analysis of patients referred to our center with MVD between September 2013 and February 2016 was done. A total of 95 patients were included. Each patient received an orthoptic and complete ophthalmological assessment. The outcomes studied were the age, sex of the patient, etiologies associated with MVD, angle of deviation in primary position at near and distance fixation as well as the proposed treatment.ResultsFifty men (53%) and 45 women (47%) were included with a mean age of 33 years (range 2‐86 years), without statistically significant difference of affected eye or to gender. The mean deviation angle, at far and near distances, was 10 diopters. The majority of MVD were acquired (46%), congenital (35%), residual (13%) and consecutive (6%). The most common etiology was cranial nerves IV paralysis (29% n = 26). The other etiologies were cranial nerves III paralysis (20% n = 19), residual MVD (12% n = 10), strabismus (6% n = 5), consecutive MVD (5% n = 4),cranial nerves VI paralysis (3% n = 3), Graves’ disease (3% n = 3), orbital floor fracture (1% n = 1), other etiologies (21% n = 24). Treatment was surgical for 52% of patients, prism correction (25%), eye occlusion (4%), optical correction alone (5%). Eleven per cent are regressed spontaneously and treatment was not specified for the remaining 3%.ConclusionsMVD are the most common finding in acquired oculomotor palsy. The variability of the clinical forms and etiologies makes their proper diagnosis and testing challenging. Indications of the treatment are guided by functional repercussion.

Prioritising downgaze alignment in the management of vertical strabismus for thyroid eye disease: principles and outcomes.

To evaluate outcomes of surgery for vertical strabismus in thyroid eye disease (TED) employing a set of surgical principles aimed at avoiding reversal of downgaze deviation while restoring binocular single vision (BSV). A retrospective review of consecutive patients undergoing vertical strabismus surgery for TED using a set of surgical principles between 2008 and 2017. Principle outcome measure was the presence of BSV in primary position and downgaze 3 months postoperatively and at latest follow-up. Thirty five patients (29% male) with a mean age of 58 years (range 31-83 years) were included. Median follow-up was 16 months. At presentation, 17 (49%) used monocular occlusion to avoid diplopia; the remainder used a prism and/or abnormal head posture. In 12 (34%), combined horizontal and vertical muscle surgery was required. Median (inter-quartile range) preoperative vertical deviations in primary position and downgaze respectively were 20 prism dioptres (Δ) (15, 30) and 18Δ (8, 22), which improved to 1Δ (0, 3) and 1Δ (0, 3) after the first operation. BSV in primary position and downgaze, without prism, after a single surgery was achieved in 29 (83%). Second surgery was required in 5 (14%) and one patient who had reactivation of her TED required a third surgery. At final follow-up (median 16 months), 32 (91%) were diplopia free without prisms; 3 (9%) used a small prism correction (range 2-12Δ); no patients were left with intractable diplopia. Our management principles are characterised by prioritising downgaze alignment to avoid downgaze diplopia reversal, whilst limiting adjustable sutures and employing standard surgical dosing. They give favourable outcomes in TED associated vertical strabismus.

Visual Effects of Deep Brain Stimulation in a Patient with Parkinson’s Disease

Background: Parkinson’s disease (PD) is a progressive neurodegenerative disorder caused by a dopamine deficiency that presents with motor symptoms. Visual disorders can occur concomitantly but are frequently overlooked. Deep brain stimulation (DBS) has been an effective treatment to improve tremors, stiffness and overall mobility, but little is known about its effects on the visual system. Case Report: A 75-year-old Caucasian male with PD presented with longstanding binocular diplopia. On baseline examination, the best-corrected visual acuity was 20/25 in each eye. On observation, he had noticeable tremors with an unsteady gait. Distance alternating cover test showed exophoria with a right hyperphoria. Near alternating cover test revealed a significantly larger exophoria accompanied by a reduced near point of convergence. Additional testing with a 24-2 Humphrey visual field and optical coherence tomography (OCT) of the nerve and macula were unremarkable. The patient underwent DBS implantation five weeks after initial examination, and the device was activated four weeks thereafter. At follow up, the patient still complained of intermittent diplopia. There was no significant change in the manifest refraction or prism correction. On observation, the patient had remarkably improved tremors with a steady gait. All parameters measured were unchanged. The patient was evaluated again seven months after device activation. Although vergence ranges at all distances were improved, the patient was still symptomatic for intermittent diplopia. OCT scans of the optic nerve showed borderline but symmetric thinning in each eye. All other parameters measured were unchanged. Conclusion: The case found no significant changes on ophthalmic examination after DBS implantation and activation in a patient with PD. To the best of the authors’ knowledge, there are no other cases in the literature that investigated the effects of DBS on the visual system pathway in a patient with PD before and after DBS implantation and activation.

Does an iPad fixation disparity test give equivalent results to the Mallett near fixation disparity test?

BackgroundVarious instruments have been developed to measure aligning prism, the prism that eliminates a fixation disparity (associated heterophoria). This includes the established Mallett near vision unit and recently developed Thomson Vision Toolbox on the iPad. With no previous research investigating the agreement between these instruments, practitioners may question if they can be used interchangeably. Methods80 participants underwent near vision testing with the Mallett unit and iPad fixation disparity test. Data were analysed in four ways to investigate the agreement of the two instruments. ResultsMany participants reported no fixation disparity (horizontally 46.25%, vertically 82.5%), or non-significant aligning prism (horizontally 70%, vertically 97.5%), on both instruments. The iPad revealed a larger range of aligning prism results horizontally, 6Δ base out to 15Δ base in; the Mallett unit produced a larger range of results vertically, 1Δ base up to 3.5Δ base down. More participants required a significant aligning prism on the Mallett unit horizontally and vertically. Wilcoxon signed rank analysis found that the difference in aligning prism was not statistically significant (p=0.357 horizontally, p=0.236 vertically), but 95% limits of agreement revealed clinically significant differences between the instruments. ConclusionAlthough the measured differences between the instruments are not significant in a Wilcoxon analysis, a Bland & Altman approach shows them to be in some cases clinically unacceptable, therefore the instruments should not be used interchangeably. Previous research indicates that the Mallett unit performs reasonably well at detecting symptomatic individuals and determining a prismatic correction that is likely to be helpful. Further research is required to determine the performance of the iPad test in these functions and to assess the reproducibility of both instruments.

Clinical Aspects of Prevention and Management of Primary Inferior Oblique Muscle Overaction

Background. Primary inferior oblique muscle overaction (PIOOA) may occur for various reasons and happens to 72 % patients with infantile esotropia. The criterion for the first surgical step is prevalence of vertical or horizontal deviation. The choice of tactics weakening inferior oblique muscle is ambiguous.Aims: to carry out retrospective analysis of PIOOA frequency in patients with infantile esotropia; to assess influence of esodeviation reduction by a surgical, chemodenervational or prismatic method on the existing PIOOA dynamics; to assess clinical and functional results of PIOOA treatment.Methods and methods. The retrospective analysis of 572 patients’ cases lay in assessment of PIOOA frequency and rate in patients with infantile esotropia that manifested under 9 months, with different treatment tactics. The prospective part of the research included two groups of patients. Group 1 (106 patients, 222 eyes) – studying the influence of surgical treatment of PIOOA. Group 2 (127 patients, 207 eyes) – studying the effectiveness of surgical PIOOA treatment. Conclusion. PIOOA frequency in case of different treatment tactics for patients with infantile esotropia is from 17 to 69 %, and the degree of its clinical manifestation is from 1.2 ± 0.4 to 2.6 ± 0.8. Bilateral weakening of medial rectus muscle reduces its probability up to 17–19 %, and the degree of its manifestation up to 1.2 ± 0.4. In cases of combination of PIOOA with infantile esotropia from 20 to 25° with paretic component, it is reasonable to carry out esodeviation reduction by means of bilateral recession, chemorecession or prismatic correction as the first treatment stage, whereas the rate of existing PIOOA is credibly reduced. In cases of choice of tactics, which is necessary for clinically significant reduction or elimination of PIOOA, it is reasonable to carry out chemorecession, marginal partial myotomy or myectomy depending on the PIOOA manifestation.