Grasping behavior does not recover after sight restoration from congenital blindness.

We investigated whether early visual input is essential for establishing the ability to use predictions in the control of actions and for perception. To successfully interact with objects, it is necessary to pre-program bodily actions such as grasping movements (feedforward control). Feedforward control requires a model for making predictions, which is typically shaped by previous sensory experience and interaction with the environment.1 Vision is the most crucial sense for establishing such predictions.2,3 We typically rely on visual estimations of the to-be-grasped object's size and weight in order to scale grip force and hand aperture accordingly.4,5,6 Size-weight expectations play a role also for perception, as evident in the size-weight illusion (SWI), in which the smaller of two equal-weight objects is misjudged to be heavier.7,8 Here, we investigated predictions for action and perception by testing the development of feedforward controlled grasping and of the SWI in young individuals surgically treated for congenital cataracts several years after birth. Surprisingly, what typically developing individuals do easily within the first years of life, namely to adeptly grasp new objects based on visually predicted properties, cataract-treated individuals did not learn after years of visual experience. Contrary, the SWI exhibited significant development. Even though the two tasks differ in substantial ways, these results may suggest a potential dissociation in using visual experience to make predictions about an object's features for perception or action. What seems a very simple task-picking up small objects-is in truth a highly complex computation that necessitates early structured visual input to develop.

Recalibrating vision-for-action requires years after sight restoration from congenital cataracts.

Being able to perform adept goal-directed actions requires predictive, feed-forward control, including a mapping between the visually estimated target locations and the motor commands reaching for them. When the mapping is perturbed, e.g., due to muscle fatigue or optical distortions, we are quickly able to recalibrate the sensorimotor system to update this mapping. Here, we investigated whether early visual and visuomotor experience is essential for developing sensorimotor recalibration. To this end, we assessed young individuals deprived of pattern vision due to dense congenital bilateral cataracts who were surgically treated for sight restoration only years after birth. We compared their recalibration performance to such distortion to that of age-matched sighted controls. Their sensorimotor recalibration performance was impaired right after surgery. This finding cannot be explained by their still lower visual acuity alone, since blurring vision in controls to a matching degree did not lead to comparable behavior. Nevertheless, the recalibration ability of cataract-treated participants gradually improved with time after surgery. Thus, the lack of early pattern vision affects visuomotor recalibration. However, this ability is not lost but slowly develops after sight restoration, highlighting the importance of sensorimotor experience gained late in life.

Gaze following requires early visual experience.

Gaze understanding­a suggested precursor for understanding others' intentions­requires recovery of gaze direction from the observed person's head and eye position. This challenging computation is naturally acquired at infancy without explicit external guidance, but can it be learned later if vision is extremely poor throughout early childhood? We addressed this question by studying gaze following in Ethiopian patients with early bilateral congenital cataracts diagnosed and treated by us only at late childhood. This sight restoration provided a unique opportunity to directly address basic issues on the roles of "nature" and "nurture" in development, as it caused a selective perturbation to the natural process, eliminating some gaze-direction cues while leaving others still available. Following surgery, the patients' visual acuity typically improved substantially, allowing discrimination of pupil position in the eye. Yet, the patients failed to show eye gaze-following effects and fixated less than controls on the eyes­two spontaneous behaviors typically seen in controls. Our model for unsupervised learning of gaze direction explains how head-based gaze following can develop under severe image blur, resembling preoperative conditions. It also suggests why, despite acquiring sufficient resolution to extract eye position, automatic eye gaze following is not established after surgery due to lack of detailed early visual experience. We suggest that visual skills acquired in infancy in an unsupervised manner will be difficult or impossible to acquire when internal guidance is no longer available, even when sufficient image resolution for the task is restored. This creates fundamental barriers to spontaneous vision recovery following prolonged deprivation in early age.

Development of multisensory integration following prolonged early-onset visual deprivation.

Adult humans make effortless use of multisensory signals and typically integrate them in an optimal fashion.1 This remarkable ability takes many years for normally sighted children to develop.2,3 Would individuals born blind or with extremely low vision still be able to develop multisensory integration later in life when surgically treated for sight restoration? Late acquisition of such capability would be a vivid example of the brain's ability to retain high levels of plasticity. We studied the development of multisensory integration in individuals suffering from congenital dense bilateral cataract, surgically treated years after birth. We assessed cataract-treated individuals' reliance on their restored visual abilities when estimating the size of an object simultaneously explored by touch. Within weeks to months after surgery, when combining information from vision and touch, they developed a multisensory weighting behavior similar to matched typically sighted controls. Next, we tested whether cataract-treated individuals benefited from integrating vision with touch by increasing the precision of size estimates, as it occurs when integrating signals in a statistically optimal fashion.1 For participants retested multiple times, such a benefit developed within months after surgery to levels of precision indistinguishable from optimal behavior. To summarize, the development of multisensory integration does not merely depend on age, but requires extensive multisensory experience with the world, rendered possible by the improved post-surgical visual acuity. We conclude that early exposure to multisensory signals is not essential for the development of multisensory integration, which can still be acquired even after many years of visual deprivation.

Learning to perceive shape from temporal integration following late emergence from blindness.

Visual perception requires massive use of inference because the 3D structure of the world is not directly provided by the sensory input.1 Particularly challenging is anorthoscopic vision-when an object moves behind a narrow slit such that only a tiny fraction of it is visible at any instant. Impressively, human observers correctly recognize objects in slit-viewing conditions by early childhood,2,3 via temporal integration of the contours available in each sliver.4,5 But can this capability be acquired if one has been effectively blind throughout childhood? We studied 23 Ethiopian children which had bilateral early-onset cataracts-resulting in extremely poor vision in infancy-and surgically treated only years later. We tested their anorthoscopic vision, precisely because it requires a cascade of demanding visual inference processes to perceive veridical shape. Failure to perform the task may allow mapping specific bottlenecks for late visual recovery. The patients' visual acuity typically improved substantially within 6 months post-surgery. Still, at this stage many were unable to recover shape under slit-viewing conditions, although they could infer the direction of global motion. However, when retested later, almost all patients could judge shape in slit-conditions necessitating temporal integration. This acquired capability often transferred to novel stimuli, in similar slit-viewing conditions. Thus, learning was not limited to the specific visual features of the original shapes. These results indicate that plasticity of sophisticated visual inference routines is preserved well into adolescence, and vision restoration after prolonged early-onset blindness is feasible to a greater extent than previously thought.

The impact of late-treated pediatric cataract on intraocular pressure.

PURPOSE: To assess the intraocular pressure and visual acuity before and after pediatric congenital cataract surgery performed at a relatively older age. METHODS: A retrospective analysis of all consecutive pediatric patients diagnosed and operated for bilateral congenital cataracts during a seven-year period (2012-2018) in rural southern Ethiopia. Non-ambulatory vision was defined as hand motion or worse. The main outcome measures were intraocular pressure (IOP) and visual acuity. RESULTS: Thirty-two children were included, 17 females (53.1%), with a mean age of 11 years (± 2.83) [range, 7-18]. A total of 59 eyes were operated on. The mean follow-up was 4.8 ± 1.8 years (range, 2-8). VA improved from 20/1400 preoperatively to 20/440 postoperatively OD and 20/540 OS (p < 0.001). More eyes had ambulatory vision after cataract surgery than pre-surgery (56 eyes [95%] vs. 29 eyes [49%], p < 0.001). The IOP decreased from a mean preoperative value of 18.4 ± 7.1 mmHg to 14.5 ± 2.9 postoperatively OD (p < 0.001) and 16.3 ± 5.9 mmHg to 13.9 ± 3.5 OS (p < 0.001). Fifteen eyes (24%) had increased IOP (> 21 mmHg) preoperatively, of which three remained high after surgery. Positive correlations were found between IOP, axial length and cup-to-disc ratio. None of the patients required pressure-lowering procedures. CONCLUSION: Bilateral congenital cataracts may be associated with ocular hypertension, with possible progression to glaucoma if left untreated. Surgery at a relatively older age often was associated with a significant improvement in intraocular pressure and ambulatory vision.

Lack of Automatic Imitation in Newly Sighted Individuals.

Viewing a hand action performed by another person facilitates a response-compatible action and slows a response-incompatible one, even when the viewed action is irrelevant to the task. This automatic imitation effect is taken as the clearest evidence for a direct mapping between action viewing and motor performance. But there is an ongoing debate whether this effect is innate or experience dependent. We tackled this issue by studying a unique group of newly sighted children who suffered from dense bilateral cataracts from early infancy and were surgically treated only years later. The newly sighted children were less affected by viewing task-irrelevant actions than were control children, even 2 years after the cataract-removal surgery. This strongly suggests that visually guided motor experience is necessary for the development of automatic imitation. At the very least, our results indicate that if imitation is based on innate mechanisms, these are clearly susceptible to long periods of visual deprivation.

Size constancy following long-term visual deprivation.

We can estimate the veridical size of nearby objects reasonably well irrespective of their viewing distance. This perceptual capability, termed size constancy, is accomplished by combining information about retinal image size together with the viewing distance, or using the relational information available in the scene, via direct perception [1]. A previous study [2] showed that children typically underestimate the size of a distant object. This underestimation is reduced with time, suggesting that years of visual experience may be essential for attaining true size constancy. But what if you have had very limited vision during the early years of life? We studied 23 Ethiopian children suffering from bilateral, early-onset cataract, who were surgically treated only years after birth. Surprisingly, most children were able to estimate object size reasonably well irrespective of distance; in fact, they usually tended to overestimate the far-object size. Closer examination indicated that, although before surgery the patients were diagnosed as having a full, mature bilateral cataract, they nevertheless had some residual form of vision, typically limited to very close range. Gandhi et al.[3] earlier reported immediate susceptibility to geometric visual illusions in a similar group of newly-sighted children, concluding that size constancy was probably innate. We suggest that their immediate ability to judge physical size irrespective of distance is more likely to result from their previous visual experience.

Association of orbital decompression and the characteristics of subsequent strabismus surgery in thyroid eye disease.

OBJECTIVE: To examine the association of orbital decompression and the characteristics and outcome of subsequent strabismus surgery in patients with thyroid eye disease (TED). METHODS: Data on patients with TED who underwent orbital decompression at the Goldschleger Eye Institute, Sheba Medical Center, Israel, between January 1990 to December 2011 were extracted. The characteristics of decompression and strabismus surgeries were recorded. The outcomes and association of both surgical procedures were analyzed. Statistical analysis included distribution, Pearson correlation, and matched paired tests. RESULTS: 145 eyes underwent orbital decompression, of which 45 eyes (31.0%) underwent strabismus surgery. Esotropia developed in 70% of the patients. Men and smokers underwent strabismus surgeries after decompression procedures more frequently than women and nonsmokers (χ2 test, p = 0.07, 0.002). Moreover, patients who complained of diplopia before the decompression surgery underwent strabismus surgery more frequently (χ2 test, p = 0.005). Seventy-seven percent of the patients who underwent medial wall decompression developed esotropia (χ2 test, p = 0.004). CONCLUSIONS: To the best of our knowledge, this is the largest series in the literature examining the association between decompression and strabismus surgeries. The patients' characteristics and the orbital walls involved in the decompression procedures are associated with the characteristics of subsequent strabismus that develops thereafter. These findings may have significant implications in planning TED management.

A comparison of plusoptiX A12 measurements with cycloplegic refraction.

PURPOSE: To test the accuracy and reliability of the plusoptiX A12 in detecting amblyogenic risk factors. METHODS: We prospectively collected data on children undergoing screening with the plusoptiX A12, cycloplegic refraction, and complete ophthalmic examination. American Association for Pediatric Ophthalmology and Strabismus (AAPOS) 2013 guidelines for the detection of amblyogenic risk factors were used for plusoptiX A12 screening and comparison of the results of both examination modes. RESULTS: Data on 402 eyes of 201 children (mean age, 7.63 ± 3.41 years) was collected. Mean (with standard deviation) cycloplegic refraction results were as follows: sphere, 0.88 ± 1.5 D; cylinder, -0.61 ± 0.74 D; axis, 71.17 ± 71.04; and spherical equivalent, 0.68 ± 2.63. The plusoptiX A12 measurements were as follows: sphere, 0.58 ± 1.4 D; cylinder, -0.66 ± 0.77 D; axis, 77.3 ± 68.9; and spherical equivalent, 0.25 ± 1.3. We found a strong correlation (Pearson) for sphere (r = 0.91), cylinder (r = 0.81), and axis (r = 0.7). The mean difference of the myopic spherical component between the plusoptiX and cycloplegic refraction was -0.048 ± 0.55 (95% LoA, +1.04 to -1.14 D); for the hyperopic spherical component, 0.37 ± 0.93 (LoA, +2.20 to -1.45 D); and for the cylindrical component, 0.05 ± 0.32 (LoA, +0.68 to -0.57D). The sensitivity, specificity, positive and negative predictive values for myopia were, respectively, 86%, 93%, 82%, and 94%; for astigmatism, 85%, 98%, 88% and 98%; and for hyperopia, 40%, 100%, 100%, and 98%. CONCLUSIONS: The plusoptiX A12 accuracy is high in all subgroups but better in the myopic, astigmatic, and anisometropic subgroups. Reliability was lower in the hyperopic eyes, possibly resulting in underestimation of hyperopic refractive error.

Long-Term Results of Bilateral Medial Rectus Muscle Recession in Children with Developmental Delay.

PURPOSE: To assess the long-term results of a reduced amount of medial rectus recession in children with esotropia and developmental delay. METHODS: A retrospective chart analysis of 42 children with developmental delay who had undergone surgery for esotropia during a 20-year period in a large referral center was performed. The pre- and postoperative angle of deviation was calculated for each subject as the mean of distant and near angles measured by a cover test or the Krimsky measurement. Surgical success was categorized as esotropia or exotropia of ≤10 prism diopters (PD). The main outcome measure was a stable surgical result after several years of follow-up. RESULTS: The chart review identified 42 children who met inclusion criteria, with a mean age of 2.9 years (range, 0.8-10 years). The mean angle of esotropia prior to surgery was 44.29 ± 13.9 PD (range 20-80 PD). All patients had bilateral medial rectus muscle recessions, with a mean surgical dosage of 5.04 ± 0.62 mm per muscle, on average 0.66 mm less than the standard amount. The average postoperative follow-up was 4.6 years (median 3.67 years, range 8 months-15 years). Twenty-four children (57%) achieved surgical success, 13 (31%) were undercorrected, and 5 (12%) were overcorrected. Ten of the 18 with an unsuccessful surgical outcome underwent a second procedure. The overall surgical success rate for all patients after all procedures was 71%. CONCLUSIONS: The main reason for surgical failure after bilateral medial rectus muscle recession (BMR) in developmentally delayed children remains residual esotropia. However, with time, more patients demonstrated consecutive exotropia. Although it is difficult to achieve a stable long-term ocular alignment in children with developmental delay, satisfactory results may be achieved with additional surgical procedures. The optimal amount of primary recession and whether to perform the surgical schedules according to the Parks tables or to reduce the amount of the recession when operating on children with developmental delay is still debatable.

The Limits of Shape Recognition following Late Emergence from Blindness.

Visual object recognition develops during the first years of life. But what if one is deprived of vision during early post-natal development? Shape information is extracted using both low-level cues (e.g., intensity- or color-based contours) and more complex algorithms that are largely based on inference assumptions (e.g., illumination is from above, objects are often partially occluded). Previous studies, testing visual acuity using a 2D shape-identification task (Lea symbols), indicate that contour-based shape recognition can improve with visual experience, even after years of visual deprivation from birth. We hypothesized that this may generalize to other low-level cues (shape, size, and color), but not to mid-level functions (e.g., 3D shape from shading) that might require prior visual knowledge. To that end, we studied a unique group of subjects in Ethiopia that suffered from an early manifestation of dense bilateral cataracts and were surgically treated only years later. Our results suggest that the newly sighted rapidly acquire the ability to recognize an odd element within an array, on the basis of color, size, or shape differences. However, they are generally unable to find the odd shape on the basis of illusory contours, shading, or occlusion relationships. Little recovery of these mid-level functions is seen within 1 year post-operation. We find that visual performance using low-level cues is relatively robust to prolonged deprivation from birth. However, the use of pictorial depth cues to infer 3D structure from the 2D retinal image is highly susceptible to early and prolonged visual deprivation.

Measurement of Axial Length in an Office Setting Versus Under General Anesthesia in Infants and Toddlers: A Comparative Study.

PURPOSE: To examine whether axial length measurement in awake infants and toddlers is feasible, and whether there is a difference in axial length measurement between an office setting and under general anesthesia. METHODS: This prospective comparative case study was conducted at the Goldschleger Eye Institute, Sheba Medical Center, Israel. Using the same instruments, axial length measurements were obtained using a standard applanation technique twice: once in an office setting when the infant/toddler was awake and once under general anesthesia in the operating room. A paired t test was used to test for differences between measurements. RESULTS: Thirty-three eyes of 19 participants younger than 28 months were examined; 24 (73%) eyes had cataracts and the remainder had clear lenses. One child was excluded from the study due to lack of cooperation during axial length measurement in the office setting and another due to the lengthy gap between measurements. Of the remaining 31 children, the average age was 9 months. Average axial length measurements were shorter by 0.12 mm in the office setting than under general anesthesia (P = .14). No adverse effects were observed after axial length measurements in the office setting. CONCLUSIONS: Axial length measurement in an office setting is generally reasonable to obtain. The results showed no significant difference in the axial length measured in the two settings.

Trends in the incidence and causes of severe visual impairment and blindness in children from Israel.

PURPOSE: To describe trends in the incidence and causes of legal childhood blindness in Israel, one of the few countries worldwide that maintain a national registry of the blind. METHODS: We performed a historical cohort study of annual reports of the National Registry of the Blind (NRB) between 1999 and 2013. All data regarding demographic information, year of registration and cause of blindness of children 0-18 years of age registered for blind certification were obtained from the annual reports of the NRB. Causes of legal blindness analyzed were optic atrophy, retinitis pigmentosa, retinopathy of prematurity (ROP), albinism, other retinal disorders, cataract, and glaucoma. The main outcome measure was the incidence of new cases of certified legal blindness. RESULTS: The incidence of newly registered legally blind children in Israel almost halved from 7.7 per 100,000 in 1999 to 3.1 per 100,000 in 2013. The decline was mainly attributable to a decreased incidence of blindness resulting from retinitis pigmentosa and ROP. The incidence of registered cases due to cerebral visual impairment increased. CONCLUSIONS: During the past decade the incidence of severe childhood visual impairment and blindness declined in Israel. A continuous decline in consanguineous marriages among the Jewish and Arab populations in Israel may have contributed to the decrease in the rate of vision loss due to retinitis pigmentosa in children.

The effect of oral propranolol on intraocular pressure in infants with Sturge-Weber syndrome glaucoma.

PURPOSE: To report the effect of oral propranolol on intraocular pressure (IOP) in infants newly diagnosed with unilateral Sturge-Weber syndrome (SWS) glaucoma receiving no other treatment. METHODS: This was a prospective, nonrandomized interventional case series. Four infants presenting with unilateral SWS glaucoma with no prior treatment were treated with oral propranolol at a dose of 2 mg/kg and followed thereafter. RESULTS: Propranolol had a temporary IOP-lowering effect in 3 of 4 children after 1 week of treatment. This effect diminished thereafter and 3 of 4 children required additional medical or surgical treatment. CONCLUSIONS: Oral propranolol has a temporary effect on IOP in SWS glaucoma and is not effective as a single treatment in this syndrome, yet can serve to delay surgical treatment for a short period of time. In one case, the glaucoma was well-controlled on this medication.

Traumatic pediatric cataract in southern Ethiopia--results of 49 cases.

PURPOSE: To report the experience of two tertiary care facilities in southern Ethiopia in the treatment of traumatic pediatric cataract for a period of more than 1 year. METHODS: The medical records of consecutive traumatic pediatric cataract patients who underwent surgery at the Hawassa University and the Yirgalem University schools of medicine from July 2007 to August 2008 were retrospectively reviewed. All patients with a follow-up of at least 12 months were included. RESULTS: A total of 49 children were included. Mean patient age was 8.6 ± 0.3 years (range, 5-15 years). Of the 49 cases, 32 (65%) were caused by blunt trauma. Average follow-up period was 15 months. Postoperative visual acuity of counting fingers or better was achieved in 43 (88%) eyes compared with 5 (10%) at presentation (P < 0.0001). Better visual acuity at presentation and blunt trauma were associated with better final visual acuity. Only blunt trauma was found by multivariate analysis to influence final visual acuity (P = 0.0001). CONCLUSIONS: Visual acuity of counting fingers or better visual can be achieved in most cases. Blunt trauma is a good independent prognostic factor for visual acuity.

A review of primary congenital glaucoma in the developing world.

Primary congenital glaucoma is the most common type of infantile glaucoma, yet it remains a relatively rare disease. Treatment is principally surgical, and management lasts a lifetime. In the developing world, delayed diagnosis, limited treatment, and inadequate follow-up lead to a heavier burden on the patient and community. We highlight the epidemiology and genetics of the disease, its current management and prognosis, and the limitations facing both providers and patients in the developing world. Further efforts are necessary to provide effective, timely screening of children and allocate adequate resources to allow health care workers to reduce the rate of avoidable blindness in developing countries.

Prevalence of xerophthalmia among malnourished children in rural Ethiopia.

To assess the prevalence of eye disease among malnourished children in a rural Ethiopian health center and evaluate correlations between xerophthalmia and grades of malnutrition. A retrospective, cross-sectional survey. An institution-based cross-sectional prospective study was performed at Bushulo Health Center in rural south Ethiopia and included all children age 6 months to 14 years receiving care for malnourishment from June 1st to July 30th, 2008. Data collection involved a combination of interviews with caretakers, ocular examination by a pediatric ophthalmologist and anthropometric measurements. One hundred and seventy-three children (average age at examination 2.9 ± 0.2 years) were treated for malnutrition (97 female, 76 male). One hundred and forty-nine patients had moderate malnutrition (86.03 %) and 24 had severe malnutrition (13.9 %). The following eye diseases were diagnosed--trachoma (12.1 %), blepharitis (13.3 %) and xerophthalmia (20.8 %). Severely malnourished children were more likely to suffer from xerophthalmia than moderately malnourished children (p < 0.0001). When comparing anthropometric measurements to the diagnosis of xerophthalmia, only weight percentile showed significance (p = 0.008). Xerophthalmia is a common global cause of pediatric blindness and is highly correlated with severe malnutrition. Continued efforts are necessary to improve nutrition and outcomes in these patients.

Abnormal vertical angle kappa caused by ectopic fovea.

Abnormal angle kappa simulating strabismus has been described in cases of structural retinal disorders, such as retinopathy of prematurity, familial exudative vitroretinopathy, and retinochoroidal scars. We report a patient with abnormal vertical angle kappa caused by ectopic fovea and in the absence of any other identifiable eye disorder.