Postural control depends on early visual experience.

The present study investigated the role of early visual experience in the development of postural control (balance) and locomotion (gait). In a cross-sectional design, balance and gait were assessed in 59 participants (ages 7-43 years) with a history of (a) transient congenital blindness, (b) transient late-onset blindness, (c) permanent congenitally blindness, or (d) permanent late-onset blindness, as well as in normally sighted controls. Cataract-reversal participants who experienced a transient phase of blindness and gained sight through cataract removal surgery showed worse balance performance compared with sighted controls even when tested with eyes closed. Individuals with reversed congenital cataracts performed worse than individuals with reversed developmental (late emerging) cataracts. Balance performance in congenitally cataract-reversal participants when tested with eyes closed was not significantly different from that in permanently blind participants. In contrast, their gait parameters did not differ significantly from those of sighted controls. The present findings highlight both the need for visual calibration of proprioceptive and vestibular systems and the crossmodal adaptability of locomotor functions.

Myopic shift, refractive, and visual outcomes after 5 years of infantile cataract surgery: Our experience and review of literature.

PURPOSE: After infantile cataract surgery, axial elongation, induces a myopic shift that cannot be fully compensated by corneal flattening and the rate is unpredictable owing to the non-linear growth of the eye. The current prospective study assesses the myopic shift and visual outcomes in children undergoing cataract surgery in infancy over a follow-up period of 5 years. MATERIALS AND METHODS: A prospective study conducted at a tertiary eye care center to evaluate the five-year myopic shift, refractive and visual outcomes in infants, who underwent surgery for congenital cataract in infancy. The visual acuity, myopic shift and biometric changes are compared between the aphakia and pseudophakia group. RESULTS: The mean best-corrected visual acuity (BCVA) recorded in logMAR at 5 years for aphakia group was 0.92±0.44 and for pseudophakia group was 0.66±0.42. (pvalue: 0.002102). The myopic shift was noted to be -5.9+/-5.16 in the aphakia group whereas it was -9.01+/- 3.11 in the pseudophakia group (P value= 0.002101) at 5 years after surgery for infantile cataract. CONCLUSION: IOL implantation in eyes of infants undergoing cataract surgery is feasible in eyes that strictly satisfy the pre-operative inclusion criteria and the visual outcomes in these eyes are better compared to aphakia group at 5 years follow up. Eyes with primary IOL implantation had a higher myopic shift compared to ones without primary IOL implantation. Eyes undergoing primary IOL implantation, need higher under correction compared to the current available formulae.

Ectopia Lentis: Clinical profiles in a large cohort of children from a Tertiary Eye Care network in India.

PURPOSE: To study the clinical presentations, visual, and refractive profiles of children with congenital ectopia lentis in a large cohort of patients from a tertiary eye care network in India. MATERIALS AND METHODS: A retrospective review of electronic medical records from December 2012 to December 2020 was conducted. Two hundred and ninety-seven consecutive children ≤18 years of age at presentation were identified and analyzed for demographic details, patient distribution, lens subluxation, visual, and refractive profiles before and after the interventions. RESULTS: Five hundred and ninety-four eyes of 297 (male 56%; n = 166) patients were analyzed. The mean age at presentation was 8.74 ± 3.89. Best-corrected visual acuity (BCVA) at presentation ranged from 0.3 logMAR to 3.5 logMAR; (Snellen: 6/9 - close to face [CF]) (mean 0.89 ± 0.68). High myopia (n = 201; 33.83%) and mild astigmatism (n = 340; 57.23%) were more frequent. Temporal (n = 108; 18.18%) subluxation was most common followed by superior. Lensectomy with limited vitrectomy was performed in 243 eyes of 127 patients (40.90%). Median preoperative BCVA was 1.0 (range: 0.3-3.5 logMAR; 20/40 - CF). Median postoperative BCVA was 0.5 logMAR (6/18) in the pseudophakic group and 0.6 logMAR (6/24) in the aphakic group. Spherical equivalent in myopic children reduced from -12.06 ± 6.84D to -1.57D (-0.25D to - 5.5D) in the pseudophakic group and +9.3D (+5.5D to 15.5D) in the aphakic group. CONCLUSION: This study is a large cohort of children presenting with ectopia lentis. Following intervention, an improvement in the median BCVA and refractive correction was noted in the entire cohort.

Arachidonic acid metabolism regulates the development of retinopathy of prematurity among preterm infants.

Extremely preterm infants are at risk of developing retinopathy of prematurity (ROP), characterized by neovascularization and neuroinflammation leading to blindness. Polyunsaturated fatty acid (PUFA) supplementation is recommended in preterm infants to lower the risk of ROP, however, with no significant improvement in visual acuity. Reasonably, this could be as a result of the non-consideration of PUFA metabolizing enzymes. We hypothesize that abnormal metabolism of the arachidonic acid (AA) pathway may contribute to severe stages of ROP. The present study investigated the AA-metabolizing enzymes in ROP pathogenesis by a targeted gene expression analysis of blood (severe ROP = 70, No/Mild = 56), placenta (preterm placenta = 6, full term placenta = 3), and human primary retinal cell cultures and further confirmed at the protein level by performing IHC in sections of ROP retina. The lipid metabolites were identified by LC-MS in the vitreous humor (VH; severe ROP = 15, control = 15). Prostaglandins D2 (p = 0.02), leukotrienes B5 (p = 0.0001), 11,12-epoxyeicosatrienoic acid (p = 0.01), and lipid-metabolizing enzymes of the AA pathway such as CYP1B1, CYP2C8, COX2, and ALOX15 were significantly upregulated while EPHX2 was significantly (0.04) downregulated in ROP cases. Genes involved in hypoxic stress, angiogenesis, and apoptosis showed increased expression in ROP. An increase in the metabolic intermediates generated from the AA metabolism pathway further confirmed the role of these enzymes in ROP, while metabolites for EPHX2 activity were low in abundance. Inflammatory lipid intermediates were higher compared to anti-inflammatory lipids in VH and showed an association with enzyme activity. Both the placenta of preterm infants who developed ROP and hypoxic retinal cultures showed a reduced expression of EPHX2. These findings suggested a strong involvement of EPHX2 in regulating retinal neovascularization and inflammation. The study results underscore the role of arachidonic acid metabolism in the development of ROP and as a potential target for preventing vision loss among preterm-born infants.

Intraoperative challenges and outcomes of pediatric cataract surgery following glaucoma filtering surgery.

PURPOSE: To analyze the intraoperative challenges of cataract surgery in children, following glaucoma filtering surgery. METHODS: This was a retrospective study to analyze intra-op challenges and outcomes of pediatric cataract surgery in post-glaucoma filtration surgery eyes, between January 2007 and December 2019. RESULTS: We included 20 eyes of 16 children. The most common glaucoma surgery performed was trabeculectomy and trabeculotomy (14 eyes). The median age at the time of cataract surgery was 74.5 months. The most common cataract surgery performed was lens aspiration with posterior chamber intraocular lens implantation (LA + PCIOL) (9/20). The most common intraoperative challenge faced was difficulty in capsulorrhexis (ten eyes), followed by extension of primary posterior capsulotomy (six eyes). At the final follow up eight eyes had improvement in visual acuity, five eyes had stable visual acuity and five eyes had a drop in visual acuity. In 12/20 eyes IOL was implanted, nine eyes in-the-bag and three eyes had in ciliary sulcus. None of the IOLs in the bag had decentration of IOL. The median postoperative IOP (p = 0.12) and median number of postoperative AGM (p = 0.13) at 2 years remained stable compared to the preoperative values. The IOP remained well controlled in 4 eyes without anti-glaucoma medications and in 14 eyes with anti-glaucoma medications and none needed additional surgery for IOP control. Two eyes developed retinal detachment postoperatively. CONCLUSION: Cataract surgery in pediatric eyes with prior glaucoma surgeries, have challenges with capsulorrhexis and IOL stability. The visual outcomes were reasonably good so was the IOP control.

Bilateral optic disc collaterals secondary to high-flow dural arteriovenous fistula: a diagnostic dilemma.

A man in his 80s, with a history of diabetes, hypertension and coronary artery disease, presented with bilateral painless progressive vision loss 2 years prior. His examination showed subnormal best corrected visual acuity of 20/50 and 20/80 in the right eye and left eye (LE), respectively, grade II relative afferent pupillary defect in LE, normal anterior segment, intra-ocular pressure (IOP) and defective colour vision in both eyes (BE). Fundus examination revealed optic disc pallor, disc collaterals and grade 2 hypertensive retinopathy in BE. Automated perimetry showed advanced field loss in BE. MRI of the brain and orbits with contrast showed signs of raised intracranial pressure, and magnetic resonance angiogram of the brain showed multiple arterio-venous channels along with the right transverse and sigmoid sinuses. The patient was referred to a neuroradiologist for further evaluation, and cerebral angiogram confirmed multifocal high-flow dural arterio-venous fistulae at right jugular foramen, transverse and sigmoid sinuses. He underwent Onyx liquid embolization.

Paracentral acute middle maculopathy in a patient with Myelin Oligodendrocyte glycoprotein antibody associated optic neuritis.

Purpose: There is insufficient literature reporting the concurrent occurrence of retinal ischemic lesions with optic neuritis. In this case report, we present a distinctive instance of Optic Neuritis with a positive Myelin Oligodendrocyte glycoprotein (MOG) antibody, accompanied by retinal ischemia manifesting as paracentral acute middle maculopathy (PAMM) lesions. Observations: Our patient is a 25-year-old female who tested positive for MOG antibodies and exhibited retinal PAMM lesions without any apparent underlying ischemic cause. She received intravenous pulse steroid therapy, and her symptoms and signs completely resolved one month later. Conclusion: PAMM can serve as an initial manifestation of Myelin Oligodendrocyte glycoprotein Antibody Associated Disease (MOGAD). This case has the potential to contribute to the existing literature, facilitating a deeper exploration of the pathophysiology of retinal ischemia in MOG associated optic neuritis.

Subnormal visual acuity after compliant amblyopia therapy: residual/refractory amblyopia or co-existing pathology? - a retrospective analysis.

Purpose: To assess the prevalence of alternate etiology/co-existing pathology among patients with amblyopia, and to characterize factors contributing to over-diagnosis of amblyopia. Methods: We retrospectively reviewed records of children (from 1 January 2016 to 31 December 2019) who were initially diagnosed as "amblyopia" but later an alternate diagnosis for subnormal vision was established. Patients who had a best corrected visual acuity (BCVA) of ≤20/32 (0.2 logMAR) after compliant amblyopia therapy were divided into 2 groups: those with refractory amblyopia (BCVA improvement from baseline <1 logMAR line) and residual amblyopia (BCVA improvement from baseline >1 logMAR line). Data was collected for presence/absence of amblyogenic risk factors, history, ocular examination, and investigations leading to the final alternate diagnosis. We analyzed the factors that contributed to the initial over-diagnosis of amblyopia using the diagnostic error evaluation and research (DEER) taxonomy tool. Results: During the study period, 508 children with an initial diagnosis of amblyopia met the study criteria. Among these 508 children, 466 were diagnosed to have amblyopia alone, while 26 children (5.1%, median age: 7 years, 17 boys: 9 girls) were revised to have an alternate diagnosis/co-existing pathology. These 26 patients comprised of 2 groups: children referred to us as amblyopia but rediagnosed to have an alternate diagnosis; and a second subset, initially diagnosed by us to have amblyopia, but later found to have alternate diagnosis/co-existing pathology. Subclinical optic neuritis (50%, 13 children), and occult macular dystrophy (OMD) (38.4%, 10 children) were the most frequent alternative diagnoses. Children with ametropic amblyopia (8/26, 30.7%) were most frequently misdiagnosed. Risk factors that led to an initial diagnosis of amblyopia were: high refractive error and heterotropia in 7 patients each (26.9%), anisometropia in 12 (46.1%), and prior pediatric cataract surgery in 4(15.3%). No improvement in BCVA in 21/26 (80.7%) children led to suspicion of co-existing etiology. Other clues were optic disc pallor (11), subnormal color vision (7), history of parental consanguinity in 7, and preceding febrile illness/rhinitis in 1 child. The DEER taxonomy tool suggested that the most common reasons for diagnostic errors were over-emphasis on amblyopia. Conclusion: Our study suggests that 5% of children diagnosed with amblyopia might have co-existing/alternate etiology. Most common co-existing etiologies were subclinical optic neuropathy, and OMD. No improvement in BCVA, subtle history and examination findings prompted further workup. Not considering co-existing etiologies was the most common reason for an initial overdiagnosis of amblyopia.

Pediatric myopic strabismus fixus: clinical features and surgical outcomes of silicone band loop myopexy.

PURPOSE: To evaluate the clinical profile of myopic strabismus fixus (MSF) in children and surgical outcomes of silicone band loop myopexy. METHOD: We retrospectively reviewed records of children presenting with MSF who underwent silicone band loop myopexy between January 2008 and December 2020 at a tertiary eye care center. Data concerning demographics, refractive error, axial length, extra-ocular motility, and ocular alignment pre-operatively and post-operatively, intra- and post-operative complications, ocular and systemic associations, were evaluated. The long-term effects of band loop myopexy on ocular alignment stability, motility improvement, and myopia progression were analyzed. Surgical outcome was defined as post-operative orthotropia or heterotropia less than or equal to 20 PD. RESULTS: A total of0 eyes of 7 patients (median age: 5 years; 5 boys and 2 girls) who underwent band loop myopexy were included in the study. Among them, three children underwent bilateral and four children underwent unilateral band loop myopexy. Medial rectus recession was performed only in two patients as a part of initial procedure. The median follow-up duration was 7 years. Most of the children, i.e. six of them presented with esotropia-hypotropia and only one patient presented with exotropia-hypotropia complex. The median pre-operative measurements were esotropia of 62.5 PD, hypotropia of5 PD, and exotropia of4 PD. Postoperative average primary position deviation measured was close to 9-10 PD of esotropia. The overall motility improved to -1 from -3. CONCLUSION: The clinical profile of MSF in children is almost similar to adults. This condition is a rare entity among adults as well as children. Majority of children with MSF presented with esotropia-hypotropia complex. Silicone band loop myopexy with or without medial rectus recession proves to be a reliable surgical procedure as it provides stable outcomes in terms of ocular alignment and motility among children.

Sound suppresses earliest visual cortical processing after sight recovery in congenitally blind humans.

Neuroscientific research has consistently shown more extensive non-visual activity in the visual cortex of congenitally blind humans compared to sighted controls; a phenomenon known as crossmodal plasticity. Whether or not crossmodal activation of the visual cortex retracts if sight can be restored is still unknown. The present study, involving a rare group of sight-recovery individuals who were born pattern vision blind, employed visual event-related potentials to investigate persisting crossmodal modulation of the initial visual cortical processing stages. Here we report that the earliest, stimulus-driven retinotopic visual cortical activity (<100 ms) was suppressed in a spatially specific manner in sight-recovery individuals when concomitant sounds accompanied visual stimulation. In contrast, sounds did not modulate the earliest visual cortical response in two groups of typically sighted controls, nor in a third control group of sight-recovery individuals who had suffered a transient phase of later (rather than congenital) visual impairment. These results provide strong evidence for persisting crossmodal activity in the visual cortex after sight recovery following a period of congenital visual deprivation. Based on the time course of this modulation, we speculate on a role of exuberant crossmodal thalamic input which may arise during a sensitive phase of brain development.

Facial dysmorphism in congenital rubella syndrome.

PURPOSE: To investigate the dysmorphic facial features in congenital rubella syndrome (CRS) and describe their associations with ocular and systemic features. METHODS: The medical records of children diagnosed with CRS between 2016 and 2021 were retrospectively reviewed for ocular and systemic features. CRS was diagnosed either on the basis of positive serology for rubella antibodies or with the classic triad of congenital cataract, sensorineural hearing loss, and congenital heart defect. Children with photographic documentation of the face were analyzed independently by three experienced investigators for facial dysmorphic features (triangular face, microcephaly, broad forehead, low anterior hairline, whorl on the anterior hairline, prominent nose, micrognathia). The dysmorphic feature was recorded as present only when at least two of the three examiners confirmed its existence. RESULTS: CRS was diagnosed in 237 children: mean age at presentation, 5.45 ± 4.5 years; 126 males (53%); bilateral cataract, 176 (75%). Positive serology for rubella antibodies was noted in 153 children (65%). Photographic record of facial features was documented in 127 (54%). The most common dysmorphic facial feature was wide forehead (82 [65%]), followed by low anterior hairline with whorl (41 [32%]). However, microcornea (P = 0.9801), cataract (P = 0.8342), pupillary sphincter atrophy (P = 0.7421), and salt and pepper retinopathy (P = 0.8803) were not significantly associated with the presence of facial dysmorphism. Congenital heart disease was significantly associated with facial dysmorphism (P = 0.0308). Sensorineural hearing loss was not associated with the presence of facial dysmorphism (P = 0.8463). CONCLUSIONS: Facial dysmorphism is common in children with CRS, but it was not predictive of the presence of ocular manifestations of CRS in this cohort.

Agreement Between Virtual Reality Perimetry and Static Automated Perimetry in Various Neuro-Ophthalmological Conditions: A Pilot Study.

Our objective was to compare the agreement between virtual reality perimetry (VRP) (order of magnitude, OM) and static automated perimetry (SAP) in various neuro-ophthalmological conditions. We carried out a retrospective analysis of visual field plots of patients with various neuro-ophthalmological conditions who underwent visual field testing using VRP and SAP and between 1 January and 31 May 2022. Two fellowship-trained neuro-ophthalmologists compared the visual field defects observed on both devices. Per cent agreement was used to compare the interpretation of the two examiners on both techniques. The study criteria were met by 160 eyes from 148 patients (mean age 44 years, range 17-74 years). The most common aetiologies were optic atrophy due to various causes, optic neuritis, ischaemic optic neuropathy, and compressive optic neuropathy. Overall, we found good agreement between VRP and SAP for bitemporal (93.8%), hemianopic (90.8%), altitudinal (79.4%), and generalised visual field defects (86.4%). The agreement was acceptable for central/centrocaecal scotomas and not acceptable for enlarged blind spots. Between the two examiners there was good agreement for bitemporal (92.3%), hemianopic (82%), altitudinal (83%), and generalised field defects (76.4%). The results of our study suggest that VRP gives overall good agreement with SAP in various neuro-ophthalmological conditions, especially those likely to produce hemianopic, altitudinal, and generalised visual field defects. This could be useful in various settings; however, future larger studies are needed to explore real-world utilisation.

Early visual experience refines the retinotopic organization within and across visual cortical regions.

Early visual areas are retinotopically organized in human and non-human primates. Population receptive field (pRF) size increases with eccentricity and from lower- to higher-level visual areas. Furthermore, the cortical magnification factor (CMF), a measure of how much cortical space is devoted to each degree of visual angle, is typically larger for foveal as opposed to peripheral regions of the visual field. Whether this fine-scale organization within and across visual areas depends on early visual experience has yet been unknown. Here, we employed 7T functional magnetic resonance imaging pRF mapping to assess the retinotopic organization of early visual regions (i.e., V1, V2, and V3) in eight sight recovery individuals with a history of congenital blindness until a maximum of 4 years of age. Compared with sighted controls, foveal pRF sizes in these individuals were larger, and pRF sizes did not show the typical increase with eccentricity and down the visual cortical processing stream (V1-V2-V3). Cortical magnification was overall diminished and decreased less from foveal to parafoveal visual field locations. Furthermore, cortical magnification correlated with visual acuity in sight recovery individuals. The results of this study suggest that early visual experience is essential for refining a presumably innate prototypical retinotopic organization in humans within and across visual areas, which seems to be crucial for acquiring full visual capabilities.

Prevention and management of childhood progressive myopia: National consensus guidelines.

Myopia is a major public health problem worldwide, including India, with the global prevalence of myopia increasing rapidly over decades. The clinical and socioeconomic impact of myopia is also expected to rise with rising prevalence. Therefore, the focus has now been shifted to prevent the incidence and progression of myopia. However, there is lack of any standardized guidelines for myopia management. This document aims to generate a national-level expert consensus statement on the management of childhood myopia in the Indian scenario. The expert panel of pediatric ophthalmologists consisted of 63 members who met in a hybrid meeting. A list of topics deliberating discussion in the meeting was provided to the experts in advance and they were instructed to provide their opinions on the matter during the meet. The panel of experts then gave their views on each of the items presented, deliberated on different aspects of childhood myopia, and reached a consensus regarding the practice patterns in the Indian scenario. In case of opposing views or lack of a clear consensus, we undertook further discussion and evaluated literature to help arrive at a consensus. A written document is prepared based on recommendations explaining definition of myopia, refraction techniques, components and methods of workup, initiation of anti-myopia treatment, type and timing of interventions, follow-up schedule, and indications for revised or combination treatment. This article formulates evidence-based guidelines for progressing myopes and pre-myopes and also establishes uniformity in the management of childhood myopia in the country.

Different strokes for anterior capsulorhexis in pediatric cataract.

Background: A successful outcome in pediatric cataract surgery is determined by an intact, curvilinear anterior capsulotomy which is dependent on the type and density of cataract, the morphology of the anterior capsule, and associated anterior segment pathologies. Purpose: This video highlights 10 different techniques which can be used for capsulorhexis in pediatric cataract. Synopsis: The choice of technique for capsulorhexis in pediatric cataract is on case basis, namely the gold standard manual capsulotomy aided by rhexis forceps (1. Standard capsulorhexis/2. Vitrector, Vitrectorhexis), with an assistance from capsular staining (3. Blue-rhexis), or by coaxial illumination (4. Coaxial-rhexis) or by just the sheen of capsule (5. Sheen-rhexis). The anterior chamber can be maintained using ophthalmic visco-elastic device (Visco-rhexis) or by irrigation fluid (6. Hydro-rhexis). A speed-breaker in the routine capsulotomy is the presence of plaque which is managed by rhexis forceps (7. Plaque-rhexis) or by a vitrector (vitrectorhexis) or a pair of micro-scissors (8. Scissor rhexis). Above all, the technology of femto-second-laser-assisted (9. Femto-rhexis) and zepto-pulse-precision capsulotomy (10. Zepto-rhexis) is also illustrated. Highlights: This video highlights the 10 different techniques of capsulorhexis in pediatric cataract surgery. Video Link: https://youtu.be/TgDrk5RYdbI.

Visual outcomes and safety profile of intraocular lens implantation versus aphakia in children with microspherophakia with no subluxation.

OBJECTIVE: To study the visual, refractive and surgical outcomes of intraocular lens (IOL) implantation versus aphakia in children with microspherophakia. DESIGN: Retrospective, comparative, non-randomised interventional study. METHODS: All consecutive children with microspherophakia who satisfied the inclusion criteria were included. The eyes that underwent in-the-bag IOL implantation and those that were left aphakic were included in groups A and B, respectively. The postoperative visual outcomes, IOL stability and complications during the follow-up period were studied. RESULTS: 22 eyes (13 patients, male 76%), of which 12 eyes were in group A and 10 eyes in group B. The mean±SE of age at surgery was 9.4±1.4 and 7.3±0.9 years in group A and group B, respectively (p value 0.18). The mean follow-up of group A was 0.9±0.4 years (median 0.5 years; Q1 0.04, Q3 2.16) and group B was 1.3±0.9 years (median 0.147 years; Q1 0.08, Q3 0.39) (p value 0.76). All the baseline biometric variables including best-corrected visual acuity (BCVA) were comparable in each group. The final BCVA in logMAR adjusted for follow-up was comparable in both group A (0.29±0.06) and group B (0.52±0.09) (p value 0.06). Mean predictive error of IOL power in microspherophakia was 0.17±0.43.The most common complication in group A was visual axis opacification of two eyes (16.7%, 95% CI 2.9% to 49.1%), of which one eye (8.3%, 95% CI 0.4% to 40.2%) needed membranectomy. Vitreous in anterior chamber was the most common complication in group B, seen in two eyes (20%, 95% CI 3.5% to 55.8%), of which one eye (10%, 95% CI 0.5% to 45.9%) underwent YAG laser vitreolysis. The survival analysis (p value 0.18) was comparable in each group. CONCLUSION: In-the-bag IOL is an option, which can be considered in selected cases of microspherophakia in developing nations where regular follow-up and economic constraints are a major concern.

The development of oscillatory and aperiodic resting state activity is linked to a sensitive period in humans.

Congenital blindness leads to profound changes in electroencephalographic (EEG) resting state activity. A well-known consequence of congenital blindness in humans is the reduction of alpha activity which seems to go together with increased gamma activity during rest. These results have been interpreted as indicating a higher excitatory/inhibitory (E/I) ratio in visual cortex compared to normally sighted controls. Yet it is unknown whether the spectral profile of EEG during rest would recover if sight were restored. To test this question, the present study evaluated periodic and aperiodic components of the EEG resting state power spectrum. Previous research has linked the aperiodic components, which exhibit a power-law distribution and are operationalized as a linear fit of the spectrum in log-log space, to cortical E/I ratio. Moreover, by correcting for the aperiodic components from the power spectrum, a more valid estimate of the periodic activity is possible. Here we analyzed resting state EEG activity from two studies involving (1) 27 permanently congenitally blind adults (CB) and 27 age-matched normally sighted controls (MCB); (2) 38 individuals with reversed blindness due to bilateral, dense, congenital cataracts (CC) and 77 age-matched sighted controls (MCC). Based on a data driven approach, aperiodic components of the spectra were extracted for the low frequency (Lf-Slope 1.5 to 19.5 Hz) and high frequency (Hf-Slope 20 to 45 Hz) range. The Lf-Slope of the aperiodic component was significantly steeper (more negative slope), and the Hf-Slope of the aperiodic component was significantly flatter (less negative slope) in CB and CC participants compared to the typically sighted controls. Alpha power was significantly reduced, and gamma power was higher in the CB and the CC groups. These results suggest a sensitive period for the typical development of the spectral profile during rest and thus likely an irreversible change in the E/I ratio in visual cortex due to congenital blindness. We speculate that these changes are a consequence of impaired inhibitory circuits and imbalanced feedforward and feedback processing in early visual areas of individuals with a history of congenital blindness.

Unraveling congenital ptosis with the aid of the pediatric perimeter device.

Background: Ocular morbidity with an early onset can have a significant impact on the long-term development of an individual. Hence, careful assessment of visual functions early on is very important. However, testing infants always poses a challenge. Standard tools to assess infants' visual acuity, ocular motility, and so on rely on the clinician's quick subjective judgments of an infant's looking behavior. Eye movements are usually observed from head rotations or spontaneous eye movements in infants. Judging eye movements in the presence of strabismus is even more challenging. Purpose: This video shows a 4-month-old infant's viewing behavior captured during a visual field screening study. The recorded video aided in the examination of this infant that was referred to a tertiary eye care clinic. The additional information captured through the perimeter testing is discussed. Synopsis: The Pediatric Perimeter device was developed to address visual field extent and gaze reaction time assessment in the pediatric population. As a part of a large-scale screening study, infants' visual fields were tested. During this screening, a 4-month-old infant presented with a ptosis in the left eye. The infant was consistently missing the light stimuli presented in the left upper quadrant in the binocular visual field testing. The infant was referred to a tertiary eye care center to a pediatric ophthalmologist for further examination. During clinical examination, the infant was suspected to either have congenital ptosis or monocular elevation deficit. But the diagnosis of the eye condition was unsure owing to the poor cooperation of the infant. With the aid of Pediatric Perimeter, the ocular motility was consistent with limitation of elevation in abduction, indicating a possible monocular elevation deficit with congenital ptosis. The infant was also noted to have Marcus Gunn jaw-winking phenomenon. The parents were assured and asked for a review in 3 months. In the subsequent follow-up, the Pediatric Perimeter testing was performed, and the recording showed a full extraocular motility in both eyes. Hence, the diagnosis was changed to only congenital ptosis. The probable explanation for missing the target in the left upper quadrant in the first visit is postulated further. The left upper quadrant is the superotemporal visual field of the left eye and the superonasal visual field of the right eye. As the left eye had ptosis, the superotemporal visual field could have been obstructed and hence the stimuli missed. The normative extent for the nasal and superior visual field is just about 30° for a 4-month-old infant. Hence, the right eye also perhaps missed the stimuli in its superonasal visual field extent. This video highlights the utility of the Pediatric Perimeter device in providing a magnified view of the infant's face along with greater visibility of ocular features from the infrared video imaging. This can potentially help the clinician to easily observe different ocular/facial abnormalities such as extraocular motility disorders, lid functions, and in identifying unequal pupil size, media opacities, and nystagmus. Highlights: The presence of congenital ptosis in younger infants might predispose as superior visual field defect and could also masquerade as a limitation in elevation. Video link: https://youtu.be/Lk8jSvS3thE.

Stimulus-evoked and resting-state alpha oscillations show a linked dependence on patterned visual experience for development.

Persistent visual impairments after congenital blindness due to dense bilateral cataracts have been attributed to altered visual cortex development within a sensitive period. Occipital alpha (8-14 Hz) oscillations were found to be reduced after congenital cataract reversal, while participants performed visual motion tasks. However, it has been unclear whether reduced alpha oscillations were task-specific, or linked to impaired visual behavior in cataract-reversed individuals. Here, we compared resting-state and stimulus-evoked alpha activity between individuals who had been treated for dense bilateral congenital cataracts (CC, n = 13, mean duration of blindness = 11.0 years) and age-matched, normally sighted individuals (SC, n = 13). We employed the visual impulse response function, adapted from VanRullen and MacDonald (2012), to test for the characteristic alpha response to visual white noise. Participants observed white noise stimuli changing in luminance with equal power at frequencies between 0 and 30 Hz. Compared to SC individuals, CC individuals demonstrated a reduced likelihood of exhibiting an evoked alpha response. Moreover, stimulus-evoked alpha power was reduced and correlated with a corresponding reduction of resting-state alpha power in the same CC individuals. Finally, CC individuals with an above-threshold evoked alpha peak had better visual acuity than CC individual without an evoked alpha peak. Since alpha oscillations have been linked to feedback communication, we suggest that the concurrent impairment in resting-state and stimulus-evoked alpha oscillations indicates an altered interaction of top-down and bottom-up processing in the visual hierarchy, which likely contributes to incomplete behavioral recovery in individuals who experienced transient congenital blindness.