Transfer and retention of oculomotor alignment rehabilitation training.

Ocular alignment defects such as strabismus affect around 5% of people and are associated with binocular vision impairments. Current nonsurgical treatments are controversial and have high levels of recidivism. In this study, we developed a rehabilitation method for ocular alignment training and examined the rate of learning, transfer to untrained alignments, and retention over time. Ocular alignment was controlled with a real-time dichoptic feedback paradigm where a static fixation target and white gaze-contingent ring were presented to the dominant eye and a black gaze-contingent ring with no fixation target was presented to the nondominant eye. Observers were required to move their eyes to center the rings on the target, with real-time feedback provided by the size of the rings. Offsetting the ring of the nondominant temporal or nasal visual field required convergent or divergent ocular deviation, respectively, to center the ring on the fixation target. Learning was quantified as the time taken to achieve target deviation of 2° (easy, E) or 4° (hard, H) for convergence (CE, CH) or divergence (DE, DH) over 40 trials. Thirty-two normally sighted observers completed two training sequences separated by one week. Subjects were randomly assigned to a training sequence: CE-CH-DE, CH-CE-DE, DE-DH-CE, or DH-DE-CE. The results showed that training was retained over the course of approximately one week across all conditions. Training on an easy deviation angle transferred to untrained hard angles within convergence or divergence but not between these directions. We conclude that oculomotor alignment can be rapidly trained, retained, and transferred with a feedback-based dichoptic paradigm. Feedback-based oculomotor training may therefore provide a noninvasive method for the rehabilitation of ocular alignment defects.

Efficacy of horizontal muscle augmentation combined inferior oblique muscle shortening for pediatric strabismus: Study Protocol.

BACKGROUND: This study will explore the efficacy and safety of horizontal muscle augmentation (HMA) combined inferior oblique muscle shortening (IOMS) for the treatment of pediatric strabismus (PS). METHODS: Literature search for studies will be carried out in the following databases: Cochrane Library, MEDILINE, EMBASE, CINAHL, Web of Science, PsycINFO, CBM, and CNKI. We will search all these databases without language and publication status restrictions. Two independent authors will perform selection of studies, data collection and management, risk of bias evaluation. A third author will be consulted with the help of discrepancies. RESULTS: This study will provide a synthesis of existed evidence for HMA combined IOMS for the treatment of PS. CONCLUSION: The results of this study will provide evidence to evaluate the efficacy and safety of HMA combined IOMS for the treatment of PS, which can help to guide clinical decision-making. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42019149716.

The pursuit of stereopsis.

BACKGROUND: Pediatric ophthalmologists are increasingly expected to promote, preserve, and restore binocular vision. METHODS: Clinical studies on restoring alignment and stereopsis in the management of amblyopia, esotropia, exotropia, and complex strabismus are reviewed from the perspective of the author's published work and personal experiences. RESULTS: Treatment of amblyopia by means of optical rehabilitation, occlusion, or penalization has been reinforced by medical treatment and perceptual training with monocular or binocular video games. Studies indicate that early management of esotropia and alignment within 8Δ is required for regaining stereopsis. In the surgical management of intermittent exotropia, distance stereopsis by Frisby Davis Distance stereotest can predict better stereopsis, with patients having preoperative distance stereopsis of <70 arcsec less likely to improve after surgery. The surgeon's armamentarium for correcting alignment and restoring binocular vision include procedures such as adjustable, partial vertical rectus muscle transposition in cases of exotropic Duane syndrome and lateral rectus palsy, periosteal fixation of the globe or of the lateral rectus muscle, and medial transposition of the split lateral rectus muscle. CONCLUSIONS: The goal for present-day strabismologists is not merely to correct strabismus but also to achieve alignment of eyes in time to ensure normal development of stereopsis in children and to restore alignment and stereopsis in adults.

Reeducation of vergence dynamics improves postural control.

INTRODUCTION: The purpose was to investigate the effect of vergence reeducation on postural control, in subjects with isolated vergence disorders. MATERIAL AND METHODS: We studied the dynamics of vergence in 19 subjects (20-44 years old) using video-oculography (Eye See Cam). On the basis of orthoptic and symptomatology assessments, ten of the subjects were diagnosed for vergence disorders then vergence eye movements were reeducated with the REMOBI method (US8851669, 5 weekly sessions lasting for 35min). Postural control was measured before and after reeducation, postural recording was done in upright stance (Dynaport), with both eyes closed or open and looking a visual target located at 2m distance. RESULTS: After reeducation with REMOBI, the visual symptomatology faded away and the stereoacuity improved at least for some subjects; the vergence latency decreased significantly and the vergence accuracy increased significantly. In terms of posture, the Mean Power Frequency (MPF) of the body sway decreased significantly in both eyes open and eyes closed conditions. Considering all subjects together (i.e. healthy subjects and subjects with vergence disorders before the reeducation), the antero-posterior body sway (Root Mean Square A/P) was positively correlated with the visual symptomatology: the higher the visual symptomatology, the higher was the body sway. CONCLUSION: The results bring evidence for synergy between the quality of vergence and the quality of postural control. They open a new research line that bridges the gap between neuroscience, ophthalmology-orthoptics and posturology.

Effects of Pure Vergence Training on Initiation and Binocular Coordination of Saccades.

Purpose: We hypothesized that saccade eye movement properties, particularly latency and binocular coordination, depend on vergence quality. Methods: We studied 11 students clinically diagnosed for vergence disorders versus 8 healthy controls. Rehabilitation of vergence disorders was done with a novel research-based method, using vergence in midsagittal plane. Vergence and saccades were recorded in separate blocks, before and after five weekly rehabilitation sessions. Results: Healthy controls showed higher accuracy and velocity of convergence and divergence relative to the vergence disorders group; then rehabilitation led to significant decrease of latency and increase of gain and peak velocity of vergence. Before rehabilitation of the vergence disorders, saccade parameters did not differ significantly from healthy controls, except the binocular coordination that was significantly deteriorated. Following vergence rehabilitation, saccade properties improved: The latency decreased significantly, the gain increased particularly at far, and the binocular coordination improved significantly. Latency and accuracy improved in a durable way, with values even better than the range of accuracy measured in healthy controls; binocular coordination of saccades, although improved, did not normalize. In healthy controls, binocular coordination was optimal at 40 cm (working distance), and the vergence disorders group showed improvement at 40 cm. Results confirm the hypothesis, which is further corroborated by the correlation between vergence and saccade latency. Conclusions: Results are in line with the hypothesis of permanent interaction between saccades and vergence, even when the task requires only saccades. Relevance of such interaction is emphasized by improvements of binocular saccades through the novel research-based method of vergence rehabilitation.

Resultados de la cirugía de estrabismo mínimamente invasiva en las desviaciones horizontales / Outcomes of minimally invasive strabismus surgery for horizontal deviation

OBJETIVO: Estudiar los resultados de la cirugía de estrabismo mínimamente invasiva (MISS) en desviaciones horizontales (DH). MÉTODO: Serie de los primeros 26 casos consecutivos operados de estrabismo horizontal en nuestro hospital mediante MISS desde febrero de 2010 a marzo de 2014. RESULTADOS: Se incluyeron 40 ojos: 26 pacientes (edad media: 7,7 años [DS: 4,9]; 34,61%: hombres). Se operaron 43 músculos: 20 rectos medios y 23 rectos laterales; 28 recesiones (rango: 3-7,5 mm), 6 resecciones (rango: 6-7 mm) y 9 plegamientos (rango: 6,5-7,5 mm). Se encontraron diferencias estadísticamente significativas (p < 0,001) en la desviación horizontal en dioptrías prismáticas pre y poscirugía, con un 88,46% de buenos resultados (desviaciones finales ≤ 10 dioptrías prismáticas). No se hallaron diferencias estadísticamente significativas (p > 0,05) en la AV al día siguiente de la cirugía y a los 6 meses. Un 29,27% de los ojos presentó hiperemia leve, 48,78% moderada y 21,95% severa al primer día postoperatorio, pasando al cuarto día al 63,41%, 31,70% y 4,87% respectivamente. Las complicaciones fueron 4 casos de sangrado conjuntival intraoperatorio, una perforación escleral y 2 prolapsos de Tenon. En un caso hubo que reconvertir a incisión fornix por mala visualización. El rango del tiempo quirúrgico disminuyó desde 30 a 15 min por músculo. CONCLUSIONES: La MISS ha obtenido buenos resultados en la cirugía del estrabismo horizontal. La inflamación conjuntival es leve en la mayoría de los casos a los 4 días de la cirugía. La AV se mantiene estable y el tiempo quirúrgico va disminuyendo una vez superada la curva de aprendizaje de 4 años

OBJECTIVE: To study the outcomes of minimally invasive strabismus surgery (MISS) for treating horizontal deviation. METHOD: Case Series of the first 26 consecutive patients operated on using the MISS technique in our hospital from February 2010 to March 2014. RESULTS: A total of 40 eyes were included: 26 patients (mean age: 7.7 years old ± 4.9); 34.61%: male. A total of 43 muscles were operated on: 20 medial, and 23 lateral recti; 28 recessions (range: 3-7.5 mm), 6 resections (6-7 mm), and 9 plications (6.5-7.5 mm) were performed. No significant difference was found (P > 0 .05) for visual acuity at postoperative day 1, and 6 months after surgery. A mild hyperaemia was observed in 29.27%, moderate in 48.78%, and severe in 21.95% at postoperative day 1 and in 63.41%, 31.70% and 4.87%, respectively, at 4 days after surgery. The complications observed were 4 intraoperative conjunctival haemorrhages, 1 scleral perforation, and 2 Tenon's prolapses. A conversion from MISS to a fornix approach was necessary in 1 patient because of bad visualization. The operating time range decreased from 30 to 15 minutes. CONCLUSIONS: The MISS technique has obtained good results in horizontal strabismus surgery. The conjunctival inflammation was mild in most of the cases at postoperative day 4. The visual acuity was stable during follow-up, and operating time decreased after a 4-year learning curve

[When is the prescription of prismatic eyeglasses reasonable?]. / Wann ist eine Prismenverordnung sinnvoll?

Prismatic glasses are used to deflect rays of light. In ophthalmology, prisms are mainly used to correct double vision caused by strabismus which is acquired after early childhood. In congenital or infantile strabismus, the image of the deviated eye is usually suppressed so that double vision does not occur and prismatic glasses are not indicated. Latent strabismus is very common and only rarely leads to double vision or asthenopic symptoms so that correction with prismatic glasses is only indicated in exceptional cases. The "Measuring and Correcting Methodology after H.-J. Haase" is based on flawed assumptions, and therefore can not be recommended for the prescription of prisms.

Ocular disorders among schoolchildren in Khartoum State, Sudan.

From December 2005 to June 2007, a total screening of all 1418 government primary schools in Khartoum State, Sudan, was performed to estimate ocular problems among children aged 6-15 years. We screened 671,119 children (56.7% males) for significant refractive error and other eye ailments. Ocular problems were found in 20,321 (3.03%) children. The 3 localities with highest ocular pathology were Karary (26.2%), Ummbada (21.0%) and Jabal Awlia (15.7%). The overall prevalence of refractive error was 2.19%. Myopia was found in 10,064 (1.50%) children while 4661 (0.70%) were hyperopic. Other ocular problems included vernal keratoconjunctivitis, vitamin A deficiency, microbial conjunctivitis, strabismus and corneal opacity. Only 288 (0.04%) children were diagnosed with active trachoma: 86.5% of these were from Ummbada locality, on the periphery ofthe State, where transportation facilities are poor and poverty is widespread. Overall, 99% of the eye ailments identified are either treatable or preventable. To reduce these and to achieve the goals of Vision 2020, an effective and efficient school health programme is needed.

[Sensory disorders screening in learning disabilities]. / Interprétation du dépistage sensoriel dans les troubles des apprentissages ?

Inserm French collective expert's report describes sensory disorders screening. However, the causality link with learning disorders remains questionable. In auditory disorders, there are high-level proof recommendations: early and intensive treatment improves language development, at least partially. For visual disorders, consensus conferences recognize their high frequency in learning disorders but there is no proof of a direct causality link. Currently, in learning disorders, orthoptic treatment is not recommended as a specific therapy. In France, despite medical ignorance about orthoptic assessment, absence of reference values and lack of therapy benefits evaluation, orthoptic treatment is usually prescribed, without any objective criteria. This article makes a literature review concerning the link between learning and sensory disorders. It also describes a typical orthoptic assessment with vision and optic musculature evaluation, and reports its results in a prospective comparative study in three populations (controls, dyslexic and Developmental Coordination Disorders [DCD] children). Strabismus or binocular vision disorders are frequent in DCD. Combined ocular motor function is almost constantly disturbed in DCD (90 %), whereas 34 % of dyslexic children and only 13 % of controls are concerned. Visual disorders are therefore present in learning disorders but also in normal population. Orthoptic assessment results must be interpreted in a multidisciplinary evaluation context.

[Traumatic III nerve palsy]. / Therapiekonzept für traumatische Okulomotoriusparesen.

Ptosis, anisocoria, loss of accommodation, incomitant exotropia, vertical and torsional disorders are the obstacles for binocularity after a traumatic III nerve palsy when a usable fusion field of vision with a more or less level head is to be acheived. To accept monocular vision may be the best choice in many cases. Therapeutic efforts to restore binocularity must deal with all aspects of the palsy. Strongly contraindicated are uncritical ptosis operations or simple repositioning interventions on the fellow eye to merely reduce the angle. Those who have a good knowledge of the entire spectrum of ocular muscle surgery, have experienced contact lens specialists at hand, and are proficient in all procedures of refractive lens surgery may, after comprehensive patient counselling, attempt to treat these patients and can in isolated cases achieve functionally useful results.

[Visual neurorehabilitation of patients with cerebral damage using botulinum toxin]. / ción visual con toxina botulínica en pacientes con daño cerebral.

BACKGROUND: The neurorehabilitation of the patient with cerebral damage implies the reestablishment of the visual functions. Botulinum toxin can be considerate as a less invasive alternative for treatment. OBJECTIVE: to demonstrate the answer to the treatment using botulinum toxin of the visual motor alterations in patients with cerebral damage. METHODS: Descriptive study of patients with visual alterations associated to cerebral damage. The visual treatment included three areas: sensorial, refracting and motor under quimiodenervation with botulinum toxin, of May 2009 to May 2010. RESULTS: 48 patients were studied, age 22,4 years ± 23. The strabismus were: esotropia 52%, exotropia 39,5%, vertical 8%, nystagmus 4%. 50% of the patients had psychomotor delay. Some of the most important causes of cerebral damage were: Down syndrome, epilepsy, tumor, hydrocephalus, neuroinfection, infantile cerebral paralysis, multiple sclerosis, metabolic syndrome, cranial trauma, congenital cardiopathy, ventricular hemorrhage, cerebrovascular stroke. The dose of botulinum toxin was 8,1 UI ± 3. We registered good results in 56.5%, regular 23,9% and bad 19,5%. The global percentage of rehabilitation was 69% of correction with a r of Pearson of 0,5. DISCUSSION: Patients with cerebral damage have diverse types of visuomotor alterations, strabismus and nystagmus.Use of botulinum toxin as a paralytic muscle agent is a good alternative in these cases. CONCLUSION: The botulinum toxin is an effective option for the visual rehabilitation in patients with cerebral damage and prevents the progression of more cerebral changes secondary to strabismus.

Brief daily periods of unrestricted vision preserve stereopsis in strabismus.

PURPOSE: This study examines whether brief periods of binocular vision could preserve stereopsis in monkeys reared with optical strabismus. METHODS: Starting at 4 weeks of age, six infant monkeys were reared with a total of 30 prism diopters base-in split between the eyes. Two of the six monkeys wore prisms continuously, one for 4 weeks and one for 6 weeks. Four of the six monkeys wore prisms but had 2 hours of binocular vision daily, one for 4, one for 6, and two for 16 weeks. Five normally reared monkeys provided control data. Behavioral methods were used to measure spatial contrast sensitivity, eye alignment, and stereopsis with Gabor and random dot targets. RESULTS: The same pattern of results was evident for both local and global stereopsis. For monkeys treated for 4 weeks, daily periods of binocular vision rescued stereopsis from the 10-fold reduction observed with continuous optical strabismus. Six weeks of continuous strabismus resulted in stereo blindness, whereas daily periods of binocular vision limited the reduction to a twofold loss from normal. Daily periods of binocular vision preserved stereopsis over 16 weeks of optical strabismus for one of the two monkeys. CONCLUSIONS: Two hours of daily binocular vision largely preserves local and global stereopsis in monkeys reared with optical strabismus. During early development, the effects of normal vision are weighed more heavily than those of abnormal vision. The manner in which the effects of visual experience are integrated over time reduces the likelihood that brief episodes of abnormal vision will cause abnormal binocular vision development.

Identification of binocular vision dysfunction (vertical heterophoria) in traumatic brain injury patients and effects of individualized prismatic spectacle lenses in the treatment of postconcussive symptoms: a retrospective analysis.

OBJECTIVE: To identify a form of binocular vision dysfunction (vertical heterophoria) in a traumatic brain injury (TBI) population and to assess the effect of individualized prismatic spectacle lenses on postconcussive symptoms. DESIGN: Retrospective study. SETTING: Private physical medicine and rehabilitation practice and private optometric practice. PATIENTS: A subset of TBI patients who were initially evaluated by a single physiatrist and who received standard treatments and medications yet had persistent postconcussive symptoms. These patients were then assessed by a single optometrist, and those found to have vertical heterophoria were treated with individualized prismatic spectacle lenses. A total of 83 patients were referred for testing; 77 were positive for vertical heterophoria on screening, of which 43 had complete data sets and were included for analysis. INTERVENTIONS: All patients were treated with individualized prismatic spectacle lenses to correct for vertical heterophoria. MAIN OUTCOME MEASURES: Outcomes were measured by the difference in score before and after intervention of an objective, self-administered vertical heterophoria symptom burden instrument (Vertical Heterophoria Symptom Questionnaire [VHS-Q], presently undergoing validation) and by subjective improvement in symptoms as expressed by the patient at the end of intervention. RESULTS: There was a 71.8% decrease in subjective symptom burden when compared with preintervention baseline. There was a mean 16.7 point absolute reduction in the VHS-Q score on a 75-point scale, which represents a relative reduction in VHS-Q score of 48.1%. CONCLUSION: Vertical heterophoria was identified in a group of TBI patients with postconcussive symptoms and treatment of the vertical heterophoria with individualized prismatic spectacle lenses resulted in a 71.8% decrease in subjective symptom burden and a relative reduction in VHS-Q score of 48.1%. It appears that vertical heterophoria can be acquired from TBI.

Vergence position of rest: spontaneous variability.

BACKGROUND: We determined the vergence position of rest (horizontal component) in two sessions, 1 to 6 weeks apart. Each session contained 8 trials. Twenty observers with normal eyes looked through Risley prisms that allowed a continuous modulation of their strength. We asked the observers to look at a fully fusionable picture, and to adjust the prisms such that viewing appeared most relaxing. The viewing distances were 400 cm and 50 cm. RESULTS: The standard deviation among the 8 trials of each session, averaged over the two sessions, the viewing distances of 400 cm and 50 cm, and the 20 observers, was + or -1.4 prism dioptres (cm/m). From the first session to the second, many observers changed the preferred prism significantly. At a viewing distance of 400 cm, 10 of 20 observers changed their preferred prism by more than 1.0 prism diopter, up to 3.3 prism diopters. At a viewing distance of 50 cm, 11 of 20 observers changed their preferred prism by more than 1.0 prism diopter, up to 5.1 prism diopters. CONCLUSIONS: The prismatic strength estimated as being most relaxing can be very variable. Before considering a prescription, the practitioner should determine whether the preferred prismatic strength remains reasonably stable. To ascertain this consistency, more than one session seems to be necessary.

Predictability of strabismus surgery in children with developmental disorders and/or psychomotor retardation.

BACKGROUND: Children with developmental disorders and/or psychomotor delay may respond differently to strabismus surgery than children who develop normally, but the literature is conflicting. METHODS: We studied 37 patients with spasm, trisomy 21, prematurity, epilepsy, psychomotor retardation, and/or hydrocephalus (study group) and 67 control patients, all between 14 months and 14 years of age. All received a recession of one or both medial rectus muscles (Rc-surgery) or a monocular recession-resection of medial-lateral rectus muscles (RcRs-surgery) for esotropia. Rc-surgery was performed in cases with convergence excess. Spectacles were prescribed prior to surgery for all hyperopia > 2D, all partly accommodative esotropia, and all myopia. RESULTS: (effect per mm of surgery): For Rc-surgery, after 2 months follow-up, at 2.5 m fixation distance, the effects (change of angle per millimeter of surgery, mean + or - SD) were 2.07 + or - 0.82 degrees /mm (study group) and 1.07 + or - 0.74 degrees /mm (control group) (P < 0.001). At 30 cm fixation distance, the effects were 2.42 + or - 0.79 degrees /mm (study group) and 1.53 + or - 1.00 degrees /mm (control group) (P < 0.001). Effects at infinity were similar to those at 2.5 m. Because of this larger effect on near angles, convergence excess decreased after surgery in both study and control groups. For RcRs-surgery, at 2.5 m fixation distance, the effects were 1.78 + or - 0.43 degrees /mm (study group) and 1.78 + or - 0.42 degrees /mm (control group) (P = 0.741). At 30 cm fixation distance, the effects were 1.82 + or - 0.39 degrees /mm (study group) and 1.84 + or - 0.58 degrees /mm (control group) (P = 0.918). At fixation distance infinity, results were similar to those at 2.5 m. For both Rc-surgery and RcRs-surgery, reported differences were similar after one year follow-up. Success of surgery: After 2 months of follow-up, esotropia between 0-6 degrees was present, for Rc-surgery in 64% in the study group (with adjusted dosages) and 93% in the control group; and for RcRs-surgery in 66% in the study group and 88% in the control group. CONCLUSIONS: Rc-surgery in children with developmental disorders and/or psychomotor delay has a larger effect per mm of surgery than in normal children. RcRs-surgery has a similar effect in delayed and normal children.

The prism that aligns fixation disparity does not predict the self-selected prism.

BACKGROUND: Associated phoria is defined as the prism that aligns monocular markers in a fixation disparity (FD) test. We examined whether the 'FD-aligning prism' predicts the 'self-selected prism' (SSP), i.e. the prism that the observer judges to be most comfortable when viewing fully fusionable images. METHODS: For the FD-aligning prism, we employed a test target with a central fusion lock. To determine the SSP, identical images were shown to both eyes. The images were displayed on a cathode-ray tube monitor at a distance of 50 cm, separated for the two eyes by means of liquid crystal shutter goggles. The observer adjusted counter-rotating prisms, recorded with a potentiometer. The procedure was repeated about 1-6 weeks later. RESULTS: Among the 20 non-strabismic subjects over two sessions, there were 16 instances in which the FD-aligning prism indicated a vergence position further in the eso direction than the SSP (< or =15.9 cm m(-1) = prism dioptre). In five instances, the FD-aligning prism indicated a vergence position further in the exo direction (< or =3.6 cm m(-1)). From the first to the second session, changes of > or=1.0 cm m(-1) occurred for the FD-aligning prism in 8/20 observers (< or =11.5 cm m(-1)), and for the SSP in 11/20 observers (< or =5.1 cm m(-1)). DISCUSSION: We hypothesise that the discrepancy between the SSP and the FD-aligning prism may be attributable to the fact that the SSP was determined while the eyes were presented with identical images, whereas the FD-aligning prism was determined while the images for the right and left eyes were different in the area of the Nonius lines. The unusual experience of binocular rivalry around the Nonius lines may have influenced the vergence of the eyes. Considering the spontaneous changes observed within an interval of 1-6 weeks, in both the FD-aligning prism and the SSP, we feel that research on the repeatability of methods for prescribing prisms is indicated.

Vertical phoria and postural control in upright stance in healthy young subjects.

OBJECTIVE: To test the quality of postural performance in quiet upright stance in healthy young adults with vertical heterophoria (VH) within the normal range and without VH (vertical orthophoria, VO). METHODS: Twenty-six subjects took part in this study. The postural stability was measured with a force platform while the subjects fixated a target at eye level in a straight ahead position, placed at either 40 or 200cm. RESULTS: The results indicated that the postural control was better for subjects with VO than subjects with VH. Particularly, there was an interaction between vertical phoria and distance: the subjects with VH showed greater instability than the subjects with VO at a far distance only. An additional study showed that the cancellation of VH with a prism improved postural stability. CONCLUSIONS: The quality of postural performance in quiet upright stance was lower in the subjects with VH. We speculate that VH, even when small in size, indicates a perturbation of the somatosensory/proprioceptive loops involved in postural control. SIGNIFICANCE: Vertical phoria could perhaps indicate the capacity of the central nervous system to integrate optimally proprioceptive cues.