Pediatric Ophthalmology

IMPORTANCE: Although durable medical equipment and supplies (DMES) are commonly used to optimize the health and function in pediatric patients, little is known about the prevalence of use and spending on DMES. OBJECTIVE: To categorize the Healthcare Common Procedure Coding System (HCPCS) for distinguishing DMES types, and to measure the prevalence and related spending of DMES in pediatric patients using Medicaid. DESIGN, SETTING, AND PARTICIPANTS: This study is a cross-sectional analysis of the 2018 Merative Medicaid Database and included 4 569 473 pediatric patients aged 0 to 21 years enrolled in Medicaid in 12 US states from January 1 to December 31, 2018. Data were analyzed from February 2019 to April 2023. EXPOSURE: DMES exposure was identified with the Centers for Medicare & Medicaid Services HCPCS codes. Three pediatricians categorized HCPCS DMES codes submitted by vendors for reimbursement of dispensed DMES into DMES types and end-organ systems; 15 expert reviewers refined the categorization (2576 DMES codes, 164 DMES types, 14 organ systems). MAIN OUTCOMES AND MEASURES: The main outcome was DMES prevalence & Medicaid spending. The χ2 test was used to compare DMES prevalence and Wilcoxon rank sum tests were used to compare per-member-per-year (PMPY) spending by complex chronic conditions (CCC). RESULTS: Of the 4 569 473 patients in the study cohort, 49.3% were female and 56.1% were aged 5 to 15 years. Patients used 133 of 164 (81.1%) DMES types. The DMES prevalence was 17.1% (95% CI, 17.0%-17.2%) ranging from 10.1% (95% CI, 10.0%-10.2%) in patients with no chronic condition to 60.9% (95% CI, 60.8%-61.0%) for patients with 2 or more CCCs. The PMPY DMES spending was $593, ranging from $349 for no chronic condition to $4253 for 2 or more CCCs. Lens (7.9%), vision frames (6.2%), and orthotics for orthopedic injury (0.8%) were the most common DME in patients with no chronic condition. Enteral tube / feeding supplies (19.8%), diapers (19.2%), lower extremity orthotics (12.3%), wheelchair (9.6%), oxygen (9.0%), and urinary catheter equipment (4.2%) were among the most common DMES in children with 2 or more CCCs. CONCLUSIONS AND RELEVANCE: In this cross-sectional study, HCPCS distinguished a variety of DME types and use across pediatric populations. Further investigation should assess the utility of the HCPCS DMES categorization with efforts to optimize the quality and safety of DMES use.

IMPORTANCE: Untreated refractive error contributes to the racial, ethnic, and socioeconomic disparities in visual function of adolescent children in the US. OBJECTIVE: To describe patterns in vision testing as a function of age among US adolescents and identify sociodemographic factors associated with vision testing. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study used data from the National Survey of Children's Health (2018-2019), a nationally representative survey of the noninstitutionalized US pediatric population. A total of 24 752 adolescent children (aged 12 to <18 years) were included. Data were analyzed from March 22 to August 11, 2023. MAIN OUTCOMES AND MEASURES: The primary outcome was the caregiver report of vision testing within the last 12 months. Linear regression was used to describe the patterns in reported vision testing as a function of participant age. Logistic regression was used to describe the association of sociodemographic factors with the report of vision testing in each setting. RESULTS: Among 24 752 adolescents, the median (IQR) age was 14 (13-16) years; 12 918 (weighted, 51%) were male. Vision testing in any setting within the previous year was reported by caregivers of 18 621 adolescents (weighted, 74%). Vision testing was reported to have occurred at an eye clinic in 13 323 participants (weighted, 51%), at a primary care clinic in 5230 participants (weighted, 22%), at a school in 2594 participants (weighted, 11%), and at a health center in 635 participants (weighted, 4%). The percentage of adolescents reported to have vision tested decreased with age (-1.3% per year; 95% CI, -2.5% to 0% per year) due to a decrease in testing in primary care and school settings. After adjusting for age and sex, there were lower odds of vision testing reported for adolescents who were uninsured vs insured (adjusted odds ratio [AOR], 0.81; 95% CI, 0.76-0.87), had caregivers with less than vs greater than high school education (AOR, 0.89; 95% CI, 0.84-0.95), and were from a family born outside vs inside the US (AOR, 0.90; 95% CI, 0.82-0.98). CONCLUSIONS AND RELEVANCE: In this cross-sectional study, vision testing in adolescents decreased as a function of age due to fewer reported tests performed in primary care and school-based settings. Relative to children in socioeconomically advantaged families, those from disadvantaged families were less likely to report receiving vision testing in clinical settings. Efforts to expand the role of school-based vision testing for older adolescents from disadvantaged backgrounds may enable opportunities to address disparities in untreated refractive error.

PURPOSE: To compare amblyopia treatment outcomes between patients with neurodevelopmental disorders and their typically developing peers. METHODS: Of 2,311 patients diagnosed with amblyopia between 2010 and 2014 at Boston Children's Hospital, 460 met inclusion criteria (age 2-12 with anisometropic, strabismic, or mixed amblyopia [interocular difference (IOD) ≥2 lines]). Treatment and visual outcomes were analyzed according to neurodevelopmental status: neurodevelopmental delay (DD) versus typical development (TD). RESULTS: The DD group (n = 54) and TD group (n = 406) were similar in demographics, amblyogenic risk factors, baseline visual measures, prescribed therapy, and adherence (P ≥ 0.10). Between-visit follow-up time was longer for the DD group (0.65 [0.42- 0.97] years) than for the TD group (0.5 [0.36-0.82] years; P = 0.023). IOD improved similarly in each group by the last visit (DD, -0.15 logMAR [-0.31 to -0.02]; TD, -0.2 logMAR [-0.38 to -0.1]; P = 0.09). Each group reached amblyopia resolution by the last visit at similar frequencies (DD, 23/54 [43%]; TD, 211/406 [52%]; P > 0.2). DD diagnosis did not independently influence amblyopia resolution (HR, 0.77; 95% CI, 0.53-1.12; P = 0.17), but each additional month of interval time between follow-up visits reduced the likelihood of resolution by 2.7% (HR, 0.67; 95% CI, 0.51-0.87; P = 0.003). CONCLUSIONS: Patients with DD and those with TD responded similarly to amblyopia therapy; however, follow-up intervals were longer in patients with DD and correlated with the likelihood of persistent amblyopia, suggesting that greater efforts at assuring follow-up may benefit patients with DD.

BACKGROUND: A cross-sectional study was conducted to assess the comparative effectiveness of virtual visits for preoperative evaluation and surgical decision-making in three pediatric surgical subspecialties. METHODS: Patients who underwent surgical procedures in the departments of Urology, Ophthalmology, and Plastic and Oral Surgery at a tertiary care pediatric hospital over a one-year period during the COVID-19 pandemic were included. Patients were assigned to one of three clinical pathways based on their preoperative visit(s): only in-person visit(s) (IP), a combination of in-person and virtual visit(s) (IP/VV), and only virtual visit(s) (VV). Demographics, procedure information, and patient experience survey results were collected. We then assessed variations in procedure types and patient experience scores in these three patient groups. RESULTS: There were 431 patients who completed the modified patient experience survey. The most common procedures were circumcision (17%), excision of lesion (16%), and strabismus repair (11%). Survey results were positive, with 90% of participants rating that they would recommend the service to others. No significant differences were found among groups in their demographics, overall care rating, and duration between preoperative clinic visit and procedure. Post-hoc power analysis indicated 87% power to detect a 10% difference in survey ratings between IP and VV cases, confirming non-inferiority in patient satisfaction for virtual preoperative visits. CONCLUSION: This study demonstrated the non-inferiority of preoperative virtual visits in three pediatric surgical subspecialties as measured by patient experience scores. Additional studies with more granular scope are necessary to further elucidate telemedicine's safety and efficacy for select diagnoses. LEVEL OF EVIDENCE: III.

We describe a novel method for clinical ophthalmic photography that uses the inherent macro-photography mode available in most recent smartphones, without additional attachments. This method facilitates acquisition of high-quality external and anterior segment clinical photography in children who may have difficulty remaining still enough for anterior segment photography at the slit lamp. We describe this technique and discuss its advantages and limitations.

BACKGROUND: We investigated ophthalmological outcomes at 2.5 years of corrected age in children born extremely preterm (EPT) to evaluate the effects of postnatal enteral supplementation with ω-3 and ω-6 long-chain polyunsaturated fatty acids. METHODS: In the Mega Donna Mega clinical trial, EPT infants born at less than 28 weeks of gestation were randomized to receive an enteral supplementation of docosahexaenoic acid (DHA) and arachidonic acid (AA) from birth to 40 weeks postmenstrual age. In this exploratory follow-up at 2.5 years of corrected age, we assessed visual acuity (VA), refraction, manifest strabismus, and nystagmus. Satisfactory VA was defined as ≥20/63. Multiple imputation (MI) was used to address the issue of missing data. FINDINGS: Of 178 children in the trial, 115 (with median gestational age (GA) of 25 + 4/7 weeks and median birth weights of 790 g) were ophthalmologically assessed at a median corrected age of 2.7 years (range 2.0-3.9 years). VA assessment was missing in 42.1% (75/178), in 41.7% (35/84) of the AA/DHA supplemented infants, and in 42.6% (40/94) of the control infants. After MI and adjustments for GA, study center, plurality, and corrected age at VA exam, no significant effect of AA/DHA supplementation was detected in VA outcome (≥20/63) (odds ratio 2.16, confidence interval 95% 0.99-4.69, p = 0.053). INTERPRETATION: In this randomized controlled trial follow-up, postnatal supplementation with enteral AA/DHA to EPT children did not significantly alter VA at 2.5 years of corrected age. Due to the high loss to follow-up rate and the limited statistical power, additional studies are needed. FUNDING: The Swedish Medical Research Council #2020-01092, The Gothenburg Medical Society, Government grants under the ALF agreement ALFGBG-717971 and ALFGBG-971188, De Blindas Vänner, Knut and Alice Wallenberg Foundation - Wallenberg Clinical Scholars, NIHEY017017, EY030904BCHIDDRC (1U54HD090255 Massachusetts Lions Eye Foundation) supported the study.

Identifying and planning treatment for retinopathy of prematurity (ROP) using telemedicine is becoming increasingly ubiquitous, necessitating a grading system to help caretakers of at-risk infants gauge disease severity. The modified ROP Activity Scale (mROP-ActS) factors zone, stage, and plus disease into its scoring system, addressing the need for assessing ROP's totality of binocular burden via indirect ophthalmoscopy. However, there is an unmet need for an alternative score which could facilitate ROP identification and gauge disease improvement or deterioration specifically on photographic telemedicine exams. Here, we propose such a system (Telemedicine ROP Severity Score [TeleROP-SS]), which we have compared against the mROP-ActS. In our statistical analysis of 1568 exams, we saw that TeleROP-SS was able to return a score in all instances based on the gradings available from the retrospective SUNDROP cohort, while mROP-ActS obtained a score of 80.8% in right eyes and 81.1% in left eyes. For treatment-warranted ROP (TW-ROP), TeleROP-SS obtained a score of 100% and 95% in the right and left eyes respectively, while mROP-ActS obtained a score of 70% and 63% respectively. The TeleROP-SS score can identify disease improvement or deterioration on telemedicine exams, distinguish timepoints at which treatments can be given, and it has the adaptability to be modified as needed.

PURPOSE: Determine sensitivity, specificity, and cut-off of macular ganglion cell layer (GCL) volume consistent with optic atrophy in children with syndromic craniosynostosis (CS). Investigate whether obstructive sleep apnea (OSA), Chiari malformation, history of elevated intracranial pressure (ICP), CS diagnosis, age, or sex independently alter GCL volume with CS. DESIGN: Retrospective cross-sectional study. SUBJECTS: Patients with syndromic CS evaluated at Boston Children's Hospital (2010 - 2022) with reliable macular optical coherence tomography (OCT) scans. METHODS: Latest ophthalmic examination that included OCT macula scans was identified. Age at examination, sex, ethnicity, best-corrected logMAR visual acuity, cycloplegic refraction, and funduscopic optic nerve appearance were recorded in addition to history of primary or recurrent elevated ICP, Chiari malformation and OSA. Spectral domain-OCT software quantified segmentation of macula retinal layers, and was manually checked. MAIN OUTCOME MEASURES: Primary outcome was determining sensitivity, specificity and optimal cutoff of GCL volume consistent with optic atrophy. Secondary outcome was determining possible independent association of previously elevated ICP, OSA, Chiari, CS diagnosis, logMAR acuity, age, or sex with altered GCL volume. RESULTS: Median age at examination was 11.9 years (interquartile range (IQR), 8.5-14.8 years). Fifty-eight of 61 patients had reliable macula scans, 74% were female, and diagnoses were Apert (n=14); Crouzon (n=17); Muenke (n=6); Pfeiffer (n= 6); and Saethre-Chotzen (n=15). Optimal cutoff identifying optic atrophy was GCL volume <1.02mm3 with a sensitivity of 83% and specificity of 77%. Univariate analysis demonstrated significantly lower macular GCL volume with optic atrophy on fundus exam (P<0.001), Apert syndrome (P<0.001), history of elevated ICP (P=0.015), Chiari malformation (P=0.001), OSA (P<0.001), in males (P=0.027) and with worse logMAR acuity (-0.36, P<0.001). Multivariable median regression analysis confirmed that only OSA (P=0.005), optic atrophy on fundus exam (P=0.003), and worse logMAR acuity (P=0.042) independently associated with lower GCL volume. CONCLUSIONS: Macular GCL volume <1.02mm3 predicted optic atrophy in patients with CS with sensitive of 83% and specificity of 77%. OSA, a treatable often concomitant disorder, was independently associated with lower GCL volume. Surveillance for optic neuropathy by GCL volume proved effective in a population where cognitive skills can limit acquisition of other key ophthalmic measures.

PURPOSE: To review the published literature assessing the clinical utility of genetic testing in individuals with infantile nystagmus syndrome (INS), defined as binocular conjugate nystagmus and onset prior to 6 months of age, with or without associated findings. METHODS: A literature search was last conducted in October 2022. The results were limited to articles published in English. The search yielded 517 abstracts, of which 72 papers were reviewed in full text. Of these papers, 4 met the criteria for inclusion and were graded by a study methodologist. RESULTS: The 4 studies that met inclusion criteria used next-generation sequencing with gene panels ranging from 31 to 336 genes. The overall molecular diagnostic rate ranged from 35% to 60% in the included studies, although the yield was higher when genetic testing was guided by clinical phenotyping (approximately 80%) and in the subsets of patients with a family history (up to 88%). As many as 30% of patients tested had a reclassification of the diagnosis based on the genetic testing results. CONCLUSIONS: Genetic testing has the potential to provide a definitive diagnosis and identify treatable conditions in patients presenting with INS, especially when considered in conjunction with clinical phenotyping and family history.

OBJECTIVES: To describe trends in vision screening based on insurance claims for young children in the United States. METHODS: This cross-sectional study used administrative claims data from the 2010-2019 IBM MarketScan Commercial Claims and Encounters Database. We included children aged 1 to <5 years at the beginning of each calendar year. The primary outcome was a vision screening claim within 12 months for chart-based or instrument-based screening. Linear regression was used to evaluate trends over time in vision screening claims and practitioner payment. RESULTS: This study included a median of 810 048 (interquartile range, 631 523 - 1 029 481) children between 2010 and 2019 (mean [standard deviation] age, 2.5 [1.1] years; 48.7% female). The percentage of children with vision screening claims increased from 16.7% in 2010 to 44.3% in 2019 (difference, 27.5%; 95% confidence interval, 27.4% to 27.7%). Instrument-based screening claims, which were identified in <0.2% of children in 2010, increased to 23.4% of children 1 to <3 years old and 14.4% of children 3 to <5 years old by 2019. From 2013 to 2018, the average of the median practitioner payment for instrument-based screening was $23.70, decreasing $2.10 per year during this time (95% confidence interval, $0.85 to $3.34; P = .009). CONCLUSIONS: Vision screening claims among young children nearly tripled over the last decade, and this change was driven by increased instrument-based screening for children aged <3 years. Further investigation is needed to determine whether the decreasing trends in practitioner payment for screening devices will reduce the adoption of vision screening technology in clinical practice.

PURPOSE: To review the published literature on the use of levodopa/carbidopa to augment the treatment of amblyopia. METHODS: Literature searches for English language studies were last conducted in October 2022 in the PubMed database with no date restrictions. The combined searches yielded 55 articles, of which 23 were reviewed in full text. Twelve of these were considered appropriate for inclusion in this assessment and were assigned a level of evidence rating by the panel methodologist. Nine studies were rated level I, and 3 studies were rated level II; there were no level III studies. RESULTS: The duration of treatment was limited to 3 to 16 weeks because of concern about long-term adverse effects such as tardive dyskinesia. This complication was not reported in any of the study participants. The dose of levodopa ranged from 1.5 to 8.3 mg/kg/day, generally divided into 3 daily doses. The carbidopa dose was approximately 25% of the levodopa dose in all treatments. Evidence from these studies indicates that augmenting traditional patch occlusion therapy with the oral administration of levodopa/carbidopa can improve the vision of amblyopic children, but the effect was small (0.17-0.3 logarithm of the minimum angle of resolution [logMAR] units) and only statistically significant when compared with patching alone in 2 of the 12 studies cited. Regression of vision was reported in the majority of studies (9 of 12 reported; range, 0-0.17 logMAR unit regression) after discontinuation of therapy. Short-term side effects of the medications were not consistently reported but were most frequently mild and included headache and nausea. CONCLUSIONS: The best available evidence is currently insufficient to show that augmenting amblyopia therapy using up to 16 weeks of levodopa/carbidopa will result in meaningful improvement in visual acuity. Given the potential for significant side effects such as tardive dyskinesia with long-term therapy, levodopa/carbidopa does not appear to be a viable option for amblyopia therapy FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

IMPORTANCE: Uncorrected refractive error is the most common cause of vision impairment in children. Most children 12 years or older can achieve visual acuity (VA) of 20/25 or better by self-refraction using adjustable-focus spectacles, but data on younger children are lacking. OBJECTIVE: To assess refractive accuracy, corrected VA, and factors associated with not achieving VA of 20/25 or better among children aged 5 to 11 years performing self-refraction with Adspecs adjustable-focus spectacles (Adaptive Eyecare), compared with noncycloplegic autorefraction and cycloplegic refraction. DESIGN, SETTING, AND PARTICIPANTS: This was a cross-sectional noninferiority trial conducted from September 2, 2015, to December 14, 2017. The study setting was an academic pediatric eye clinic. Children aged 5 to 11 years with uncorrected VA of 20/40 or worse in 1 or both eyes and without systemic or ocular conditions preventing best-corrected VA of 20/25 or better were enrolled. Children who had best-corrected VA worse than 20/25 were excluded. Study data were analyzed from September 2017 to June 2023. EXPOSURES: Children were taught to self-refract with adjustable-focus spectacles. MAIN OUTCOMES AND MEASURES: Spherical equivalent refractive error (using self-refraction, noncycloplegic autorefraction, and cycloplegic refraction) and VA (uncorrected and using self-refraction, noncycloplegic autorefraction, and cycloplegic refraction) for study eyes were evaluated. Potential predictors of failure to achieve VA of 20/25 or better with self-refraction were assessed using logistic regression. RESULTS: A total of 127 consecutive children were enrolled. After exclusions, 112 children (median [IQR] age, 9.0 [8.0-10.3] years; 52 boys [46.4%]) were included in the study. Mean (SD) spherical equivalent refractive power was -2.00 (1.52) diopters (D) for self-refraction, -2.32 (1.43) D for noncycloplegic autorefraction, and -1.67 (1.49) D for cycloplegic refraction. Mean (SD) difference in refractive power between self-refraction and noncycloplegic autorefraction was 0.32 (1.11) D (97.5% 1-sided CI, 0.11 to ∞ D; P < .001) and between self-refraction and cycloplegic refraction was -0.33 (1.15) D (97.5% 1-sided CI, -0.54 to ∞ D; P = .77). The proportion of children with corrected VA of 20/25 or better was 79.5% (89 of 112) with self-refraction, 85.7% (96 of 112) with noncycloplegic autorefraction, and 79.5% (89 of 112) with cycloplegic refraction (self-refraction vs noncycloplegic autorefraction: McNemar P value = .27; self-refraction vs cycloplegic refraction: McNemar P value > .99). Those failing to achieve best-corrected VA of 20/25 or better with self-refraction had higher astigmatism (odds ratio [OR], 10.6; 95% CI, 3.1-36.4; P < .001) and younger age (OR, 1.5; 95% CI, 1.1-2.2; P = .02). CONCLUSIONS AND RELEVANCE: Self-refraction among children aged 5 to 11 years may result in more myopic power than cycloplegic refraction but not necessarily to a clinically relevant degree. Although the proportion of children achieving VA of 20/25 or better with self-refraction using adjustable-focus spectacles did not differ from cycloplegic refraction, it was less likely among younger children and those with higher astigmatism.

PURPOSE: The purpose of this study was to test the hypothesis that retinopathy of prematurity (ROP) prolongs development of rod-mediated thresholds for detection of stimuli at 10 degrees but not 30 degrees eccentricity. In addition, to evaluate the thresholds at each site for an association with visual acuity (VA) and spherical equivalent (SE). METHODS: We estimated rod-mediated dark-adapted thresholds (DATs) for the detection of 2 degree diameter, 50 ms, blue (λ < 510 nm) flashes at 10 degrees and 30 degrees eccentric in former preterm subjects (n = 111), stratified by ROP severity: None (n = 32), Mild (n = 66), and Severe (n = 13). We also tested Term-born (n = 28) controls. To determine the age at half-maximal sensitivity (Agehalf) for each group and eccentricity, we fit DATs to logistic growth curves. We obtained VA and SE for Preterm subjects and evaluated the course of threshold development at 10 degrees and 30 degrees for significant association with VA and SE predicted at age 10 years. RESULTS: DAT development at 10 degrees was significantly delayed in ROP (Mild and Severe); ROP did not significantly alter DAT development at 30 degrees. At age 10 years, among Preterm subjects, both VA and SE were significantly associated with group (None,Mild, and Severe). SE was predicted by the course of DAT development at 30 degrees. VA was not associated with the course of DAT development at 10 degrees. CONCLUSIONS: At 10 degrees, ROP-whether mild or severe-is associated with significant delays in DAT development, evidence that the late-maturing central retina is vulnerable to ROP. The association of 30 degree threshold and myopia are evidence that more peripheral retina is important to refractive development.

We combined data from 121 amblyopic children enrolled in two prospective open-label pilot studies and a randomized trial of a binocular digital therapeutic to identify factors associated with positive response to amblyopia treatment. Visual acuity improved ≥1 line in 81% of participants after 12 weeks of therapy. Treatment response was not found to be associated with age, severity of amblyopia, or prior treatment status. Although these findings may suggest broad efficacy for this treatment approach, further investigation in larger cohorts is needed to identify factors associated with treatment response.

BACKGROUND: With the SARS-CoV-2 pandemic (COVID-19), data on central and peripheral nervous system involvement, including those causing cranial nerve 6 (CN6) palsy, have been limited to case reports. To extract clinically relevant features of COVID-19-related CN6 palsy, we report on a recurrent pediatric case and analysis of reported cases associated with infection or immunization. METHODS: A PubMed search revealed 18 cases of isolated CN6 palsy in addition to the index case (n = 19). Clinical characteristics, workup, and temporal associations between systemic symptoms onset or vaccination, symptoms onset, and resolution were compiled and analyzed. RESULTS: The median age of CN6 onset was 43 years (interquartile range [IQR]: 28-52). Sixteen cases (84.2%) were associated with COVID-19 illness and 3 (15.8%) were associated with COVID-19 vaccination. Four cases (23.5%) had positive neuroimaging findings. The median latency from first COVID-19 symptoms or vaccination to onset of CN6 palsy was 6 days (IQR: 2.3-16), and the median time from onset to resolution was 30 days (IQR: 14-60). Latency to onset of CN6 palsy was significantly and directly associated with time to resolution (R2 = 0.401, P = 0.010). Patients who had a positive SARS-CoV-2 antibody test had significantly longer days from symptoms to onset (6.0 vs 24.5, P = 0.030), and patients with a positive SARS-CoV-2 polymerase chain reaction test had a significantly shorter time to resolution (17.50 vs 90, P = 0.042). CONCLUSIONS: Isolated CN6 palsy from COVID-19 is rare, can occur in infants as young as 7 months, and can be recurrent. Longer latency from systemic symptoms onset portends greater recovery times, and this relationship may reflect multiple mechanisms by which COVID-19 (and/or an immune response thereto) causes cranial neuropathies with direct clinical relevance.