Long term ophthalmic sequelae of prematurity

Visual acuity outcomes up to 12 years and risk factors for visual impairment in a national cohort of extremely preterm born children - The Extremely Preterm Infants in Sweden Study (EXPRESS)

PURPOSE

The Extremely Preterm Infants in Sweden Study (EXPRESS) followed a national cohort of extremely preterm born (EPT, i.e. <27 weeks) children until 12 years of age. This study aimed to investigate the longitudinal development of visual acuity (VA) in children born EPT, explore the predictive value of early visual assessments, and evaluate risk factors for visual impairment at the age of 12 years.

METHODS

All 462 children born EPT in Sweden during April 2004-March 2007, and surviving to age 6.5 years, and full-term born matched controls were invited to participate in the 12-year follow-up. VA was assessed at 12 years and the results were compared with values at 2.5 and 6.5 years.

RESULTS

At age 12, 332 (72%) EPT survivors and 189 controls were examined. The mean VA in the EPT group was lower than in the control group (1.15, 95%CI [1.12-1.19] vs. 1.33, 95% CI [1.29-1.37]). Fifteen (4.5%) EPT had visual impairment. The examination at age 2.5 failed to identify most of them, while the examination at 6.5 could predict the final visual outcome at 12. Risk factors for visual impairment were low gestational age, moderate and severe intraventricular haemorrhage, treatment-requiring retinopathy of prematurity, cerebral palsy, and cognitive disability.

CONCLUSION

In this national cohort, the VA outcome at age 12 was lower in children born EPT than full-term controls. As eye examination at 2.5 years did not reliably identify visual impairment, clinical risk factors should be considered in the screening of children born EPT to early identify the visually impaired.

Long-term ocular sequelae in preterm Thai infants: A comprehensive retrospective study

Prematurity can lead to various ocular conditions, including strabismus, refractive errors, amblyopia, and cataracts. However, comprehensive data on these outcomes in preterm Thai infants is limited. This study aimed to investigate the incidence of retinopathy of prematurity (ROP) and assess long-term ocular sequelae, such as cataracts, refractive errors, strabismus, and amblyopia, among preterm infants at Phramongkutklao Hospital. A retrospective review of medical records was conducted for premature infants screened for ROP between January 2011 and April 2022. Data were collected at birth, and follow-up visits were analyzed at 6 months, 1 year, and 2 years of age. The primary outcomes included the incidence of ROP and the prevalence of long-term ocular sequelae. A total of 308 preterm infants were included in the study. The incidence of ROP was found to be 31.5%. At the 2-year follow-up, the prevalence of cataracts was 0.65%, strabismus 14.4%, and amblyopia 6%. Refractive errors were observed in 51.8% of the infants, with 18.1% showing myopia and 33.7% hyperopia. Logistic regression analysis indicated that delayed growth and development (adjusted odds ratio = 13.28, 95% confidence interval: 1.83-96.68) and amblyopia (adjusted odds ratio = 19.65, 95% confidence interval: 2.85-135.54) were significantly associated with an increased risk of developing strabismus, after adjusting for confounding factors. The study identified an ROP incidence of 31.5% in the preterm cohort. At 2 years, long-term ocular sequelae included a prevalence of cataracts (0.65%), strabismus (14.4%), amblyopia (6%), and refractive errors (51.8%). Delayed growth and development, along with amblyopia, were found to elevate the risk of strabismus development significantly.

Prevalence and causes of ocular disorders and visual impairment among preterm children in Ethiopia

OBJECTIVE

The aim of this study was to determine the prevalence, causes of ocular disorders and visual impairment among preterm children previously admitted to neonatal intensive care units in Addis Ababa, Ethiopia.

METHODS AND ANALYSIS

A prospective screening survey was conducted from February to June 2019 at the paediatric eye clinic of Menelik II Hospital. Children who were preterm at birth and who attended the eye clinic were included in the study. Data on demographic and neonatal characteristics, neonatal and maternal comorbidities and ocular disorders were collected. OR and univariate analysis were used to identify predictors of ocular diseases and visual impairment.

RESULTS

There were 222 children included in the study with a mean age at presentation of 2.62 years (range 2.08-6.38 years), mean gestational age 34.11 weeks (range 30-36) weeks and mean birth weight 1941.72 g (range 953-3500 g). Nearly two-thirds had ocular disorders with refractive error (51.8%), strabismus (11.3%) and a history of retinopathy of prematurity (ROP) (7.2%) being more common. One-fourth of the children had visual impairment, and the prevalence of amblyopia was 40.1%. Uncorrected refractive errors, strabismus and ROP were causes for visual impairment.

CONCLUSION

Visual impairment and amblyopia are common in Ethiopia. There is a need to develop a screening protocol for ocular disorders for preterm children to enhance early detection and prevention of childhood visual impairment.

A MULTICENTER STUDY OF RETINOPATHY OF PREMATURITY FOLLOW-UP ADHERENCE

PURPOSE

Characterize clinical and socioeconomic factors that impact follow-up to complete retinal vascularization and subsequent pediatric ophthalmology follow-up in neonates with retinopathy of prematurity.

METHODS

Medical records of 402 neonates diagnosed with retinopathy of prematurity from neonatal intensive care units at the University of California, Los Angeles Mattel Children's Hospital and the University of California, Los Angeles Santa Monica Hospital, both academic medical centers, and the Harbor-University of California, Los Angeles Medical Center, a safety-net county hospital, were reviewed. Primary study outcomes were the rate of follow-up to complete retinal vascularization and adequate pediatric ophthalmology follow-up. Secondary outcome was the rate of nonretinal ocular comorbidity.

RESULTS

In whole-cohort analysis, 93.6% of neonates were followed to complete retinal vascularization, and 53.5% had adequate pediatric ophthalmology follow-up. Public insurance was associated with lower rates of pediatric ophthalmology follow-up (Odds ratio 0.66, 95% confidence interval 0.45-0.98, P = 0.04). Participants screened at the academic medical center had lower rates of pediatric ophthalmology follow-up compared with the safety-net county hospital (50.7% vs. 63.5%, P = 0.034). In subgroup analysis, academic medical center participants with public insurance were less likely to have pediatric ophthalmology follow-up than safety-net county hospital participants with public insurance (36.5% vs. 63.8%, P < 0.001) or those with private insurance at the academic medical center (36.5% vs. 59.2%, P< 0.001).

CONCLUSION

This study identified high follow-up rates to complete retinal vascularization, lower pediatric ophthalmology follow-up rates, and nonretinal ocular comorbidity at all hospitals. Insurance status relative to hospital type was identified as a risk factor for loss to follow-up. This demonstrates a need to further study health care disparities in retinopathy of prematurity infants.

Prevalence and risk factors of disabilities among Egyptian preschool children: a community-based population study

BACKGROUND

Child disability has significant implications on their well-being and healthcare systems.

AIM

This survey aimed to assess the magnitude of seven types of disability among Egyptian children aged 1 < 6 years and their socio-demographic, epidemiological, and perinatal predictors.

METHODS

A national population-based cross-sectional household survey targeting 21,316 children from eight governorates was conducted. The screening questionnaire was derived from the WHO ten-question survey tool validated for identifying seven disability categories.

RESULTS

The percentage of children with at least one disability was 8.1% as follows: speech/communication (4.4%), Mobility/physical (2.5%), Seizures (2.2%), Comprehension (1.7%), Intellectual impairment (1.4%), Visual (0.3%) and Hearing (0.2%). Age was not found to affect the odds of disability except for visual disability (significantly increased with age (AOR = 1.4, 95% CI:1.1-1.7). Male sex also increased the odds of all disabilities except visual, hearing, and seizures. Convulsions after birth significantly increased the odds of disability as follows: hearing (AOR = 8.1, 95% CI: 2.2-30.5), intellectual impairment (AOR = 4.2, 95% CI: 2.5-6.9), and mobility/physical (AOR = 3.4, 95% CI: 2.3-5.0). Preterm delivery and being kept in an incubator for more than two days after birth increased the odds for visual disability (AOR = 3.7, 95% CI: 1.1-12.1 & AOR = 3.7, 95% CI: 1.7-7.9 respectively). Cyanosis increased the odds of seizures (AOR = 4.7, 95% CI: 2.2-10.3). Low birth weight also increased the odds for all disability domains except for visual and hearing. Maternal health problems during pregnancy increased the odds for all types of disability except hearing and seizures. Higher paternal education decreased the odds for all disabilities by at least 30% except for vision and hearing.

CONCLUSION

The study found a high prevalence of disability among Egyptian children aged 1-6 years. It identified a number of modifiable risk factors for disability. The practice of early screening for disability is encouraged to provide early interventions when needed.

Prevalence and risk factors of disabilities among Egyptian preschool children: a community-based population study

Background

Child disability has significant implications on their well-being and healthcare systems. Aim: This survey aimed to assess the magnitude of seven types of disability among Egyptian children aged 1 < 6 years and their socio-demographic, epidemiological, and perinatal predictors.

Methods

A national population-based cross-sectional household survey targeting 21,316 children from eight governorates was conducted. The screening questionnaire was derived from the WHO ten-question survey tool validated for identifying seven disability categories.

Results

The percentage of children with at least one disability was 8.1% as follows: speech/communication (4.4%), Mobility/physical (2.5%), Seizures (2.2%), Comprehension (1.7%), Intellectual impairment (1.4%), Visual (0.3%) and Hearing (0.2%). Age was not found to affect the odds of disability except for visual disability (significantly increased with age (AOR = 1.4, 95% CI:1.1–1.7). Male sex also increased the odds of all disabilities except visual, hearing, and seizures. Convulsions after birth significantly increased the odds of disability as follows: hearing (AOR = 8.1, 95% CI: 2.2–30.5), intellectual impairment (AOR = 4.2, 95% CI: 2.5–6.9), and mobility/physical (AOR = 3.4, 95% CI: 2.3–5.0). Preterm delivery and being kept in an incubator for more than two days after birth increased the odds for visual disability (AOR = 3.7, 95% CI: 1.1–12.1 & AOR = 3.7, 95% CI: 1.7–7.9 respectively). Cyanosis increased the odds of seizures (AOR = 4.7, 95% CI: 2.2–10.3). Low birth weight also increased the odds for all disability domains except for visual and hearing. Maternal health problems during pregnancy increased the odds for all types of disability except hearing and seizures. Higher paternal education decreased the odds for all disabilities by at least 30% except for vision and hearing.

Conclusion

The study found a high prevalence of disability among Egyptian children aged 1–6 years. It identified a number of modifiable risk factors for disability. The practice of early screening for disability is encouraged to provide early interventions when needed.

Association Between Retinal Microanatomy in Preterm Infants and 9-Month Visual Acuity

Importance

Preterm infants are at risk for poor visual acuity (VA) outcomes, even without retinal problems on ophthalmoscopy. Infant retinal microanatomy may provide insight as to potential causes.

Objective

To evaluate the association between preterm infant retinal microanatomy and VA at 9 months' corrected age.

Design, Setting, and Participants

This prospective observational study took place from November 2016 and December 2019 at a single academic medical center and included preterm infants enrolled in Study of Eye Imaging in Preterm Infants (BabySTEPS). Infants were eligible for enrollment in BabySTEPS if they met criteria for retinopathy of prematurity (ROP) screening, were 35 weeks' postmenstrual age or older at the time of first OCT imaging, and a parent or guardian provided written informed consent. Of 118 infants enrolled in BabySTEPS, 61 were included in this analysis. Data were analyzed from March to April 2021.

Exposures

Bedside optical coherence tomography (OCT) imaging at a mean (SD) 39.85 (0.79) weeks' postmenstrual age and monocular grating VA measurement at 9 months' corrected age.

Main Outcomes and Measures

Presence and severity of macular edema and presence of ellipsoid zone at the fovea measured by extracting semiautomated thicknesses of inner nuclear layer, inner retina, and total retina at the foveal center; choroid across foveal 1 mm; and retinal nerve fiber layer (RNFL) across the papillomacular bundle (PMB). Pearson correlation coefficients were calculated and 95% CIs were bootstrapped for the association between retinal layer thicknesses and continuous logMAR VA. Associations were analyzed between retinal microanatomy and normal (3.70 cycles/degree or greater) vs subnormal grating VA at 9 months' corrected age using logistic regression and with logMAR VA using linear regression, adjusting for birth weight, gestational age, and ROP severity at the time of OCT imaging and accounting for intereye correlation using generalized estimating equations.

Results

The mean (SD; range) gestational age of included infants was 27.6 (2.8; 23.0-34.6) weeks, and mean (SD; range) birth weight was 958.2 (293.7; 480-1580) g. In 122 eyes of 61 infants, the correlations between retinal layer thicknesses and logMAR VA were as follows: r, 0.01 (95% CI, -0.07 to -0.27) for inner nuclear layer; r, 0.19 (95% CI, 0.01 to 0.35) for inner retina; r, 0.15 (95% CI, -0.02 to 0.31) for total retina; r, -0.22 (95% CI, -0.38 to -0.03) for choroid; and r, -0.27 (95% CI, -0.45 to 0.10) for RNFL across the PMB. In multivariable analysis, thinner RNFL across the PMB (regression coefficient, -0.05 per 10-μm increase in RNFL thickness; 95% CI, -0.10 to -0.01; P = .046) and prior ROP treatment (regression coefficient, 0.33 for ROP treatment; 95% CI, 0.11 to 0.56; P = .003) were independently associated with poorer 9-month logMAR VA.

Conclusions and Relevance

In preterm infants, RNFL thinning across the PMB was associated with poorer 9-month VA, independent of birth weight, gestational age, need for ROP treatment, and macular microanatomy. Evaluation of RNFL thickness using OCT may help identify preterm infants at risk for poor vision outcomes.

Ophthalmological Impairments at Five and a Half Years after Preterm Birth: EPIPAGE-2 Cohort Study

We report the 51/2 year prevalence of visual and oculomotor impairments in preterm children born at 24−34 weeks’ gestation (WG) using the population-based cohort study EPIPAGE-2, set in France, 2011. The main outcomes were imputed prevalence of refractive errors (REs), strabismus, and binocular visual acuity (VA). Children were clinically assessed by specially trained pediatricians. The population was also analyzed in terms of cerebral palsy at 51/2 years (no CP, stage 1, stage 2, or stage 3−5) and retinopathy of prematurity in the neonatal period (no ROP, stage 1 or 2, or severe ROP). Among the 4441 children included, 2718 (weighted percentage 58.7%) were clinically assessed. REs were reported in 43.1% (95% confidence interval 37.6−48.4), 35.2% (32.7−37.6), and 28.4% (25.0−31.8) of children born at 24−26, 27−31, and 32−34 WG (p < 0.01), respectively; strabismus rates were 19.5% (14.6−24.4), 14.8% (12.9−16.7), and 8.3% (6.2−10.4) (p < 0.001), respectively. Moderate/severe visual deficiencies (VA < 3.2/10) were present in 1.7% (0.2−3.3) of children born at 24−26 WG, and in less than 1% in other groups. A suboptimal VA 5/10−6.3/10 was measured in 40.6% (35.3−45.8) of children born at 24−26 WG, 35.8% (33.5−38.1) at 27−31 WG, and 33.7% (30.4−37.0) at 32−34 WG. CP and ROP were associated with strabismus and RE. The association between CP and VA was strong, while it was not observed for ROP. In this large cohort of preterm-born children, we found a high prevalence of RE and strabismus regardless of WG, supporting the need for specific attention in this population. High prevalence of suboptimal VA could be challenging for these children at the age of reading and writing acquisition.

Key factors in a rigorous longitudinal image-based assessment of retinopathy of prematurity

To describe a database of longitudinally graded telemedicine retinal images to be used as a comparator for future studies assessing grader recall bias and ability to detect typical progression (e.g. International Classification of Retinopathy of Prematurity (ICROP) stages) as well as incremental changes in retinopathy of prematurity (ROP). Cohort comprised of retinal images from 84 eyes of 42 patients who were sequentially screened for ROP over 6 consecutive weeks in a telemedicine program and then followed to vascular maturation or treatment, and then disease stabilization. De-identified retinal images across the 6 weekly exams (2520 total images) were graded by an ROP expert based on whether ROP had improved, worsened, or stayed the same compared to the prior week’s images, corresponding to an overall clinical “gestalt” score. Subsequently, we examined which parameters might have influenced the examiner’s ability to detect longitudinal change; images were graded by the same ROP expert by image view (central, inferior, nasal, superior, temporal) and by retinal components (vascular tortuosity, vascular dilation, stage, hemorrhage, vessel growth), again determining if each particular retinal component or ROP in each image view had improved, worsened, or stayed the same compared to the prior week’s images. Agreement between gestalt scores and view, component, and component by view scores was assessed using percent agreement, absolute agreement, and Cohen’s weighted kappa statistic to determine if any of the hypothesized image features correlated with the ability to predict ROP disease trajectory in patients. The central view showed substantial agreement with gestalt scores (κ = 0.63), with moderate agreement in the remaining views. Of retinal components, vascular tortuosity showed the most overall agreement with gestalt (κ = 0.42–0.61), with only slight to fair agreement for all other components. This is a well-defined ROP database graded by one expert in a real-world setting in a masked fashion that correlated with the actual (remote in time) exams and known outcomes. This provides a foundation for subsequent study of telemedicine’s ability to longitudinally assess ROP disease trajectory, as well as for potential artificial intelligence approaches to retinal image grading, in order to expand patient access to timely, accurate ROP screening.

Comparison of the Efficiency of the Botulinum Toxin for the Treatment of Esotropia in Children with and without Neurological Disease and/or Prematurity

OBJECTIVE

To compare the effect of botulinum toxin injection for the management of esotropia in patients with and without neurological disease and/or prematurity.

METHODS

A single-center, retrospective, nonrandomized controlled study was performed on botulinum toxin in 87 children divided into two groups: study group of esotropia in 56 children with neurological disease and/or prematurity and, control group of 31 healthy children with infantile esotropia. All patients were followed for at least 24 months after injection. Success was defined as motor alignment with 10^Δ of orthotropia after single bilateral botulinum injection.

RESULTS

Mean age at treatment was similar in both groups (15.5 vs 14.8 months; p = .555). Mean pretreatment deviation was similar in both groups (50.8^Δ vs 50^Δ; p = .855). The success rate was better in the control group (61.2% vs 51.7%, p = .265) at 24 months after injection, but the change in the mean angle of deviation was not statistically significant between the groups at 12 and 24 months after injection (p = .264 and p = .547, respectively). Multivariate regression analysis showed that pretreatment angle of deviation and presence of retinopathy of prematurity were significant predictors at 12 months after injection (p = .0001 and p = .004, respectively), while pretreatment angle of deviation was found to be a predictor at 24 months after injection (p = .0001).

CONCLUSIONS

Decreased angle of deviation and absence of retinopathy of prematurity were associated with a better result. There was no difference in motor alignment of esotropia in children with and without neurological disease and/or prematurity. In these patients, botulinum injection may be used as an alternative to surgery.

What Are We Measuring as Outcome? Looking Beyond Neurodevelopmental Impairment

Outcomes of neonatal intensive care unit (NICU) graduates have been categorized by rates of neurodevelopmental impairment at 2 years old. Although useful as metrics for research, these early childhood assessments may underestimate or overestimate later functional capabilities. Often overlooked are less severe but more prevalent neurobehavioral dysfunctions seen later in childhood, and chronic health concerns that may impact the child's quality of life (QoL). Comprehensive NICU follow-up should include measures of less severe cognitive/learning delays, physical/mental well-being, and the promotion of resilience in children and families. Studies are needed to identify QoL measures that will optimize children's assessments and outcomes.

[Follow-up protocol for newborns of birthweight less than 1500 g or less than 32 weeks gestation]

The mortality of children with a birthweight of less than 1500g or with a gestational age of less than 32 weeks (<1500<32) has decreased significantly in the last 20 years or so. Given the higher risk of disability in these children, follow-up after hospital discharge is considered essential. In this document, the Follow-Up Group of the Spanish Society of Neonatology, in collaboration with the Spanish Society of Paediatric Primary Care, propose a follow-up protocol specific for the<1500<32, which has as its aim to standardise the activities and evaluations according to good practice criteria.

Bedside ROP screening and telemedicine interpretation integrated to a neonatal transport system: Economic aspects and return on investment analysis

BACKGROUND AND AIM

Peter Cerny Ambulance Service - Premature Eye Rescue Program (PCA-PERP) uses digital retinal imaging (DRI) with remote interpretation in bedside ROP screening, which has advantages over binocular indirect ophthalmoscopy (BIO) in screening of premature newborns. We aimed to demonstrate that PCA-PERP provides good value for the money and to model the cost ramifications of a similar newly launched system.

METHODS

As DRI was demonstrated to have high diagnostic performance, only the costs of bedside DRI-based screening were compared to those of traditional transport and BIO-based screening (cost-minimization analysis). The total costs of investment and maintenance were analyzed with micro-costing method. A ten-year analysis time-horizon and service provider's perspective were applied.

RESULTS

From the launch of PCA-PERP up to the end of 2014, 3722 bedside examinations were performed in the PCA covered central region of Hungary. From 2009 to 2014, PCA-PERP saved 92,248km and 3633 staff working hours, with an annual nominal cost-savings ranging from 17,435 to 35,140 Euro. The net present value was 127,847 Euro at the end of 2014, with a payback period of 4.1years and an internal rate of return of 20.8%. Our model presented the NPVs of different scenarios with different initial investments, annual number of transports and average transport distances.

CONCLUSIONS

PCA-PERP as bedside screening with remote interpretation, when compared to a transport-based screening with BIO, produced better cost-savings from the perspective of the service provider and provided a return on initial investment within five years after the project initiation.

Brief report: incidence of ophthalmologic disorders in children with autism

PURPOSE

To determine the incidence of ophthalmologic disorders in children with autism and related disorders.

DESIGN

Retrospective chart review. Four hundred and seven children diagnosed with autism or a related disorder between 1998 and 2006. one hundred and fifty-four of these children completed a comprehensive ophthalmology exam by a pediatric ophthalmologist.

RESULTS

Ophthalmologic pathology was found in 40% of patients with autism or a related disorder with 29% having significant refractive errors, 21% demonstrating strabismus, and 10% having amblyopia.

CONCLUSIONS

Children with autism or a related disorder will frequently have an ophthalmologic abnormality. Since cooperation with vision screening is understandably limited in these children, a comprehensive eye examination by a pediatric ophthalmologist is recommended for all such children.

Preterm-associated visual impairment and estimates of retinopathy of prematurity at regional and global levels for 2010

BACKGROUND

Retinopathy of prematurity (ROP) is a leading cause of potentially avoidable childhood blindness worldwide. We estimated ROP burden at the global and regional levels to inform screening and treatment programs, research, and data priorities.

METHODS

Systematic reviews and meta-analyses were undertaken to estimate the risk of ROP and subsequent visual impairment for surviving preterm babies by level of neonatal care, access to ROP screening, and treatment. A compartmental model was used to estimate ROP cases and numbers of visually impaired survivors.

RESULTS

In 2010, an estimated 184,700 (uncertainty range: 169,600-214,500) preterm babies developed any stage of ROP, 20,000 (15,500-27,200) of whom became blind or severely visually impaired from ROP, and a further 12,300 (8,300-18,400) developed mild/moderate visual impairment. Sixty-five percent of those visually impaired from ROP were born in middle-income regions; 6.2% (4.3-8.9%) of all ROP visually impaired infants were born at >32-wk gestation. Visual impairment from other conditions associated with preterm birth will affect larger numbers of survivors.

CONCLUSION

Improved care, including oxygen delivery and monitoring, for preterm babies in all facility settings would reduce the number of babies affected with ROP. Improved data tracking and coverage of locally adapted screening/treatment programs are urgently required.

Visual function at 35 and 40 weeks' postmenstrual age in low-risk preterm infants

OBJECTIVES

The objectives of this study were to (1) assess visual function in low-risk preterm infants at 35 and 40 weeks' postmenstrual age, (2) compare preterm visual abilities at term-equivalent age with term-born infants, and (3) evaluate effects of preterm extrauterine life on early visual function.

METHODS

Visual function was assessed by using a validated test battery at 35 and 40 weeks' postmenstrual age in 109 low-risk preterm infants who were born at <31 weeks' gestation. The preterm findings were compared with data from term-born infants collected by using the same test protocol.

RESULTS

All preterm infants completed both assessments. The 35-week responses were generally less mature than those at 40 weeks. Preterm infants at both ages were significantly more mature than term-born infants for ocular movements and vertical and arc tracking and at 40 weeks for stripe discrimination. In contrast, tracking a colored stimulus, attention at distance, and stripe discrimination were more mature at term age (in both term-born and preterm infants) than at 35 weeks.

CONCLUSIONS

Our findings provide data for visual function at 35 and 40 weeks' postmenstrual age in low-risk preterm infants. The results suggest that early extrauterine experience may accelerate the maturation of aspects of visual function related to ocular stability and tracking but does not seem to affect other aspects that may be more cortically mediated.