Cataracts in children

Characteristic cytokine profile of the aqueous humor in eyes with congenital cataract and pre-existing posterior capsule dysfunction

Objectives

To investigate the characteristic cytokine profile of the aqueous humor in eyes with congenital cataract and pre-existing posterior capsule dysfunction (PCD).

Methods

In this cross-sectional study, the enrolled eyes with congenital cataract and PCD were included in the PCD group, while those with an intact posterior capsule were included in the control group. Demographic data and biometric parameters were recorded. The levels of 17 inflammatory factors in the aqueous humor collected from the enrolled eyes were detected using Luminex xMAP technology, and intergroup differences in the collected data were analyzed.

Results

The PCD group comprised 41 eyes from 31 patients with congenital cataract and PCD, whereas the control group comprised 42 eyes from 27 patients with congenital cataract and an intact posterior capsule. Lens thickness was significantly thinner in the PCD group than in the control group. However, the levels of monocyte chemoattractant protein-1 (MCP-1), transforming growth factor-β2 (TGF-β2), and vascular endothelial growth factor (VEGF) were significantly higher in the PCD group than in the control group. Multivariate logistic regression confirmed that lens thickness and TGF-β2 level were independent risk factors for PCD.

Conclusion

A thinner lens thickness in eyes with congenital cataract and PCD could serve as a biometric feature of these eyes. The higher levels of MCP-1, TGF-β2, and VEGF in eyes with PCD indicated a change in their intraocular inflammatory microenvironment, which possibly led to cataract progression. Lens thickness and TGF-β2 level are independent risk factors for PCD.

A simplified sclerocorneal tunnel approach in performing pediatric cataract surgery

BACKGROUND/AIMS

Performing pediatric lensectomy, anterior vitrectomy with intraocular lens implantation in one session, using a long sclerocorneal tunnel and covering the incision site with 8/0 Vicryl sutures.

MATERIALS AND METHODS

This study includes 52 eyes of 30 patients with pediatric cataracts. At the temporal side, the conjunctival peritomy was performed, followed by two long sclerocorneal side ports and the main incision for intraocular lens (IOLs) implantation. At the end of the operation, the side port and the conjunctiva incisions were sutured with 8/0 Vicryl sutures. The IOLs were implanted in children older than 24 months, not in smaller ones. The operations and intraoperative complications were recorded. After the operation, the patients were examined on the 1st postoperative day, then six times for the first 6 months. During follow-ups, the impact of the suture on the anterior segment complications and astigmatism was evaluated.

RESULTS

The age of the patients ranged between 2 months and 8 years. The average operation time was 28 ± 6 min. Due to the suture-related complication, neither re-suturing nor stitch removal was carried out; therefore, general anesthesia was not repeated. The average astigmatism value of the children in the postoperative 1st week was 1.5 ± 1.2 D (0.5-4.0). The mean astigmatism value was 0.8 ± 0.5 D (0.5-1.5) in the 3rd postoperative month.

CONCLUSION

The long corneoscleral tunnel method has been found safe in pediatric cataract surgery.

Infantile Aphakic Glaucoma: A Proposed Mechanism

PURPOSE

To review information pertaining to secondary glaucoma following infant lensectomy and provide evidence to support the mechanism responsible for this condition.

METHODS

Reported risk factors and proposed mechanisms for infantile aphakic glaucoma are reviewed. Laboratory studies and clinical observations in affected patients with glaucoma are described. Evidence of postoperative anterior chamber fibrosis is reviewed and interpreted.

RESULTS

Clinical evidence demonstrated the development of anterior chamber fibrosis following infant cataract surgery. Laboratory studies showed liberated lens epithelial cell transition to fibroblasts.

CONCLUSIONS

The review and assessment of laboratory and clinical evidence support the proposal that infantile aphakic glaucoma is caused, in part, by postoperative anterior chamber fibroization related to lens cell dispersion, cytokine activation, and epithelial-mesenchymal transition with resultant filtration angle fibrosis and secondary loss of filtration function. [J Pediatr Ophthalmol Strabismus. 2022;59(4):236-242.].

Femtosecond laser-assisted anterior capsulotomy in children undergoing cataract surgery: a large case series

Objective

To evaluate safety and postoperative visual outcomes of low-energy femtosecond laser-assisted (FLA) anterior capsulotomy in paediatric cataract surgery.

Methods and analysis

We report a retrospective single-centre consecutive case series of 51 eyes of 33 paediatric cataract patients with a mean age of 3.22 years (range: 2 months to 13 years) who underwent cataract surgery with FLA anterior capsulotomy, using FEMTO LDV Z8 femtosecond laser (Ziemer Ophthalmic Systems). Anterior laser capsulotomy, phacoaspiration and intraocular lens implantation were performed in all eyes. Both intraoperative and long-term postoperative complications, along with long-term monocular corrected distance visual acuity (CDVA), were assessed during average follow-up period of 32.96 months (range: 13–69 months).

Results

In 48 out of 51 eyes, a well-sized and well-located anterior capsulotomy was achieved without intraoperative complications. Anterior capsule tears occurred in three eyes; however, they did not extend posteriorly and the intraocular lens were placed in the bags without any further complications. Posterior capsular opacification developed in 45.10% of eyes (23 out of 51) and was subsequently treated with neodymium:yttrium-aluminum-garnet (Nd:YAG) laser capsulotomy. Mean CDVA at final follow-up was 20/40 (range: 20/63 to 20/32) in unilateral cases younger than 12 months, 20/40 (range: 20/1000 to 20/25) in unilateral cases older than 12 months, 20/66 (range: 20/400 to 20/32) in bilateral cases younger than 12 months and 20/40 (range: 20/200 to 20/20) in bilateral cases older than 12 months.

Conclusions

Paediatric cataract surgery with low-energy FLA anterior capsulotomy is a procedure with long-term safety, resulting in significant improvement in CDVA.

Prevalence and Factors Related to Visual Impairments in Children With Bilateral Cataract Following Surgery and the Potential Need for Education and Rehabilitation Services

Introduction

Pediatric cataract is still a major cause for childhood visual impairment. The goal of our study was to analyze the prevalence of children with impaired vision (6/15 or worse) after surgery for bilateral cataract, to evaluate factors associated with it and to emphasize the importance for visual rehabilitation including the use of visual aids, educational measures, and social worker services.

Methods

Retrospective analysis of medical records from children who underwent surgery for cataract up to age 6 years, with a follow-up of at least 4 years. Clinical characteristics retrieved from medical records included visual acuity, presence of nystagmus and/or strabismus, age at surgery, intraocular lens (IOL) implantation, and others.

Results

Fifty-five children were included in the study. Follow-up ranged from 4 to 13 years (Mdn = 6.8). Visual impairment was found in 15/24 (62.5%) of children operated on before the age of 6 months (group 1), and in 7/31 (22.5%) n those operated after the age of 6 months (group 2; p = .019). Thirty-eight of the 55 children had a primary IOL implantation; nystagmus and microphthalmos were also associated with higher rates of visual impairment.

Discussion

Despite early and modern surgery, long-term visual outcome remains poor in children undergoing bilateral cataract surgery at young age. When discussing visual prognosis with parents, it is important to recognize factors associated with visual impairment, such as need for surgery before age 6 months, nystagmus and microphthalmos, as well as the importance for early visual rehabilitation services when needed.

Implications for Practitioners

Our study aims to highlight the high number of children left with visual impairment and blindness following modern and timely treatment for early cataract. Early referral for visual rehabilitation will optimize quality of life in these children and will probably allow a wider range of opportunities as adults.

Real-time intraoperative OCT imaging of the vitreolenticular interface during pediatric cataract surgery

PURPOSE

To report on the use of intraoperative optical coherence tomography (OCT) imaging of the vitreolenticular interface (VLI) during pediatric cataract surgery and to determine the incidence of VLI dysgenesis and surgical difficulties.

SETTING

Department of Ophthalmology, Antwerp University Hospital, Edegem, Belgium.

DESIGN

Retrospective cohort study.

METHODS

This study included 51 pediatric patients who underwent cataract surgery between April 2016 and December 2018. Video recordings and OCT images of the VLI were analyzed and compared. VLI dysgenesis was considered present when intraoperative OCT images demonstrated partial or total adhesions between the posterior lens capsule and the anterior hyaloid membrane. Video recordings were analyzed to describe surgical difficulties, more specifically: inability to create a calibrated primary posterior continuous curvilinear capsulorhexis (PPCCC), occurrence of vitreous prolapse, need for anterior vitrectomy, and complicated IOL implantation.

RESULTS

Of the 51 patients included, VLI dysgenesis was demonstrated in 27 patients (52.9%). The incidence of VLI dysgenesis was greater in children with unilateral cataract (72.4%), and children with a posterior capsule plaque (90%). PPCCC was challenging in 20 patients. A defect of the anterior hyaloid membrane was found in 16 patients. Anterior vitrectomy or cutting vitreous strands with scissors was necessary in 10 patients.

CONCLUSIONS

Intraoperative OCT images were an excellent tool to evaluate the VLI and to demonstrate the presence of VLI dysgenesis during pediatric cataract surgery. Performing a calibrated PPCCC was more challenging in the presence of VLI dysgenesis. This can subsequently expose a defect in the anterior hyaloid membrane, which may result in vitreous prolapse.

Commentary review: challenges of intraocular lens implantation for congenital cataract infants

As an indispensable part of congenital cataract surgery, intraocular lens (IOL) implantation in infantile patients has long-term positive impacts on visual rehabilitation, as well as postoperative complications inevitably. Timing of IOL implantation in infantile congenital cataract patients is not simply a point-in-time but a personalized decision that comprehensively takes age at surgery, risks of postoperative complications, and economic condition of family in consideration, and combines with choosing suitable IOL type and power. For infants with well-developed eyeballs and good systemic conditions, IOL implantation at six months of age or older is safe and effective. Otherwise, secondary IOL implantation may be a safer choice.

Comparative analysis of visual outcomes of multifocal and monofocal intraocular lenses in congenital cataract surgery

PURPOSE

To assess the impact on visual development of multifocal versus monofocal intraocular lenses (IOLs) implantation in children following congenital cataract surgery.

DESIGN

Retrospective interventional consecutive case series.

METHODS

We reviewed the records of 56 eyes of 43 pediatric patients who underwent congenital cataract surgery with phacoaspiration and simultaneous implantation of IOL under one year of age. Corrected distance visual acuity (CDVA), refractive error and ocular motility disorders were evaluated after a follow-up greater than 4 years.

RESULTS

We implanted 32 multifocal (18unilateral, Group A and 14bilateral, Group B) and 24monofocal IOLs (12unilateral, Group C and 12bilateral, Group D). Mean follow-up was 6.67 years. Mean CDVA of the eyes with multifocal IOL was 0.75±0.46 logMAR in unilateral cataract surgery and 0.34±0.25logMAR in bilateral ones; with monofocal IOLs was 0.71±0.52logMAR in unilateral and 0.53±0.43logMAR in bilateral ones. No statistically significant difference in CDVA between Groups A and B and Groups C and D has been recorded. Final mean spherical equivalent was -3.88±4.73D; in Group A it was -2.74±4.22D, in Group C was -1.08±1.45D, in Group B was -4.82±4.64D and in Group D was -6.81 ± 4.61D.The difference was statistically significant between Group B and D (p=0.01), but not between Group A and C (p=0.14).Twenty-six patients (60.4%) showed post-operative strabismus. Its surgical correction occurred more in patients with multifocal IOL implanted (p=0.038).

CONCLUSIONS

Our findings suggest that the use of multifocal IOLs did not show significant advantages in visual development in children following congenital cataract extraction under one year of age if compared with monofocal IOLs.

Supportive care for toxicities in children undergoing radiation therapy

Radiation therapy (RT) is an integral part of the management of many pediatric tumors; however, it is associated with both acute and permanent adverse events that can significantly impact a child's quality of life, lead to treatment delays, and potentially affect outcomes of cancer therapy. Prevention, early detection, and optimal management of these adverse effects will help reduce their impact on the patients' quality of life and overall well-being. Unfortunately, there has not been a coordinated effort to study the etiology, evaluate risk factors, and explore novel treatments for these conditions. Studies of supportive care for children undergoing RT are often small and uncontrolled. This review will focus on the impact of irradiation on the different organ systems and their current management. Further studies are required to improve our understanding of the contributing factors and explore novel treatment options for these adverse effects and to enable children and their families to better cope with some of the unavoidable toxicities following multimodality therapy.

Audit of 1000 consecutive cases of sutureless cataract surgery in children above two years of age

Purpose

To study the safety of sutureless cataract surgery and risk factors for wound leak of clear corneal incision in children affected with congenital or developmental cataract.

Methods

It is a retrospective, noncomparative interventional case study involving children in the age group of 2 to 16 years, who underwent cataract surgery with intraocular lens implantation with the minimum follow up of 1 month.

Results

Out of 1000 eyes studied, lens matter aspiration with intraocular lens implantation with or without primary posterior capsulorhexis and anterior vitrectomy was done in 609 and 391 eyes, respectively. Incisions of 943 eyes did not require sutures while sutures were applied for wound leak in 57 eyes on the table and in 5 eyes on postoperative day 1. Risk of wound leak for suture application was found to be greater in patients; having age less than 5 years (P < 0.0001), surgeries performed by junior surgeons (P < 0.0003), wound problems (P < 0.0001), intraocular lens (IOL) related factors (P < 0.0001), use of iris hooks (P < 0.0001), and anterior capsulorhexis extension (P < 0.0001). On the first postoperative day, anterior chamber reaction (P < 0.0001) and fibrinous membrane (P = 0.0007) were significantly more in the sutured group. Incidence of postoperative complications was 0.98 per sutured eyes (59 complications in 60 eyes). One patient developed endophthalmitis after suture removal.

Conclusion

Sutureless clear corneal incision in pediatric patients undergoing cataract surgery can achieve stable wound. However, after hydro closure, every wound should be checked for water tightness and the leaky wound should be sutured.

A systematic review of ultrasound biomicroscopy use in pediatric ophthalmology

Ultrasound biomicroscopy (UBM) is the only available option for noninvasive, high-resolution imaging of the intricate iridociliary complex, and for anterior segment imaging with corneal haze or opacity. While these unique features render UBM essential for specific types of trauma, congenital anomalies, and anterior segment tumors, UBM imaging has found clinical utility in a broad spectrum of diseases for structural assessments not limited to the anterior intraocular anatomy, but also for eyelid and orbit anatomy. This imaging tool has a very specific niche in the pediatric population where anterior segment disease can be accompanied by corneal opacity or clouding, and anomalies posterior to the iris may be present. Pediatric patients present additional diagnostic challenges. They are often unable to offer detailed histories or fully cooperate with examination, thus amplifying the need for high-resolution imaging. This purpose of this systematic review is to identify and synthesize the body of literature involving use of UBM to describe, evaluate, diagnose, or optimize treatment of pediatric ocular disease. The collated peer-reviewed research details the utility of this imaging modality, clarifies the structures and diseases most relevant for this tool, and describes quantitative and qualitative features of UBM imaging among pediatric subjects. This summary will include information about the specific applications available to enhance clinical care for pediatric eye disease.

Comparison of the Accuracy of IOL Power Calculation Formulas for Pediatric Eyes in Children of Different Ages

Purpose

This study aims to compare the accuracy of five intraocular lens (IOL) power calculation formulas (SRK/T, Hoffer Q, Holladay 1, Haigis, and Holladay 2) for pediatric eyes in children of different ages.

Methods

In this prospective study, patients who received cataract surgery and IOL implantation in the capsular bag were enrolled. We compared the calculation accuracy of 5 formulas at 1 month postoperatively and performed subgroup analysis with the patients divided into three groups according to their ages at the time of surgery as follows: group 1 (age ≤ 2 years, 35 eyes), group 2 (2 years < age < 5 years, 38 eyes), and group 3 (age > 5 years, 29 eyes).

Results

75 patients (102 eyes) were enrolled in this study. The Haigis formula got the smallest PE among all formulas in all three groups. With regard to APE, there were no statistical differences among the formulas except group 2, with the SRK/T formula a little smaller, the Holladay 2 formula a little larger in group 1, and the Haigis formula a little smaller in group 3. In group 2, the Haigis formula had the lowest APE (0.87 ± 0.61 D), while the Holladay 2 formula had the largest (1.71 ± 1.20 D, p < 0.001), followed by the Holladay 1 formula (1.51 ± 1.07 D, p=0.002). On comparing the percentage of APE within 0.5 D and 1.0 D obtained with 5 formulas in each group, there were no statistical differences. The SRK/T formula and the Holladay 1 formula showed the highest percentage (40.00% and 60.00%) in group 1. While the Haigis formula got the highest percentage in less than 0.5 D (34.21%) and less than 1 D (60.53%) in group 2. In group 3, the Holladay 2 formula and the Haigis formula got the highest percentage less than 0.5 D (58.62%) and less than 1 D (79.31%). The multiple linear regression indicated that the age at the time of surgery was a significant factor affecting the accuracy of APE; after removing the age, AL was the only factor that affected the accuracy of APE.

Conclusion

The SRK/T and the Holladay 1 formulas were relatively accurate in patients younger than 2 years old, while the Haigis formula performed better in patients older than 2.

Simultaneous Bilateral Pediatric and Juvenile Cataract Surgery Under General Anesthesia: Outcomes and Safety

PURPOSE

To evaluate the surgical approach, outcome, and safety of bilateral simultaneous cataract surgery (BS-Cat) compared with unilateral cataract surgery (US-Cat) and bilateral 2-timed cataract surgery (BT-Cat) in children.

DESIGN

Retrospective, interventional case series.

METHODS

Setting: Department of Ophthalmology, Medical University, Vienna, Austria.

PARTICIPANTS

Children aged 0-18 years who received cataract extraction owing to a unilateral or bilateral cataract between January 2003 and December 2018 were included. Main Outcomes and Measures: Information regarding the type and duration of surgery and total anesthesia time were recorded. Additionally, intraoperative and postoperative complications including retreatments were evaluated.

RESULTS

A total of 220 eyes of 147 patients were included in this analysis (US-Cat: n = 74 patients; BS-Cat: n = 63 patients; BT-Cat: n = 10 patients). The mean age at surgery was 15.94 ± 27.10 months in the US-Cat group, 33.47 ± 58.20 months in the BS-Cat group, and 41.91 ± 55.09 months in the BT-Cat group. The main surgical approach was lensectomy combined with anterior vitrectomy ± IOL implantation (US-Cat: 98.65%; BS-Cat: 95.24%; BT-Cat: 100%; P = .08). Initial intraocular lens implantation was not commonly performed in all groups (US-Cat: 27.03%; BS-Cat: 23.02%; BT-Cat: 50.00%). The mean anesthesia time was shortest in the US-Cat (91.62 ± 26.12 min), followed by the BS-Cat (123.81 ± 30.11 min) and BT-Cat groups (186.00 ± 42.34 min; P < .001), contrary to the duration of surgery (US-Cat: 37.56 ± 15.69 min; BS-Cat: 32.33 ± 17.31 min; BT-Cat: 37.50 ± 18.67; P = .087). An accidental oxygen decrease below 93% was rare in all groups (US-Cat: 6.76%; BS-Cat: 17.46%; BT-Cat: 10.00%). Intraoperative surgical complications occurred rarely (P = .95) and involved mainly the iris. The number of postoperative complications (P = .17) and interventions (P = .10) was similar in all groups. Visual axis obscuration (US-Cat: 28.38%; BS-Cat: 23.81%; BT-Cat: 20.00%; P = .67) and glaucoma (US-Cat: 6.76%; BS-Cat: 15.87%; BT-Cat: 15.00%; P = .20) showed no difference between the groups. However, nystagmus was more pronounced in the BS-Cat group (US-Cat: 12.16%; BS-Cat: 49.21%; BT-Cat: 20.00%; P < .001), whereas strabismus was more pronounced in the US-Cat group (US-Cat: 68.92%; BS-Cat: 33.33%; BT-Cat: 40.00%; P < .001).

CONCLUSION

Simultaneous removal of bilateral cataract in children showed no statistically significant differences regarding intraoperative and postoperative complications when compared to unilateral and 2-timed bilateral cataract surgery. Anesthesia time was longer in simultaneous bilateral than in unilateral cataract surgery, but only by the surgery time of the second eye. However, prolonged anesthesia time was not accompanied by a decrease of oxygen saturation.

Analysis and management of intraoperative and early postoperative complications of bag-in-the-lens intraocular lens implantation in different age groups of paediatric cataract patients: report of the Giessen Paediatric Cataract Study Group

PURPOSE

To report the rate and management of intra- and early postoperative complications of bag-in-the-lens intraocular lens (IOL) implantation technique for cataract treatment in paediatric patients of different age groups.

SETTINGS

Department of Ophthalmology, Justus-Liebig-University Giessen, University Hospital Giessen and Marburg GmbH, Campus Giessen, Giessen, Germany.

DESIGN

Retrospective non-randomized consecutive case series.

METHODS

Ninety eyes of 60 paediatric cataract patients were enrolled to this retrospective non-randomized observational consecutive case series single-centre study. All patients underwent cataract surgery with bag-in-the-lens IOL implantation between January 2008 and December 2018, performed by two experienced surgeons. The entire cohort was divided into four age groups: first - 0-<3 months, second - 3-<12 months, third - 12-<36 and fourth - >36 months-17 years of age. The intra- and postoperative complications were based on the clinical records. The description of management of complications related specifically to bag-in-the-lens IOL technique was based on the 39 consecutive cases operated since 1 Jan 2016 by one single surgeon that were all video documented. The early postoperative period was defined as 12 months after surgery.

RESULTS

Overall, there were 27 unilateral and 33 bilateral surgical cases of 24 female and 36 male children. The mean age at surgery was 45.25 months (range 1-200 months). The most common intraoperative events were vitreous prolapse and anterior capsule rupture with 28.9% and 13.3%, respectively. Within 12 months of follow-up, five eyes (5.6%) were re-operated because of visual axis reo-pacification (VAR). Intraocular hypertension was diagnosed in seven eyes (7.8%), including two cases that required surgical treatment. In all cases with intra- and early postoperative complications related specifically to bag-in-the-lens technique, it was possible to manage them and successfully implant bag-in-the-lens IOL.

CONCLUSIONS

Implementation of bag-in-the-lens technique in the treatment of paediatric cataract was associated with a relatively low rate of intra- and postoperative complications, including rare cases of VAR. The correct management of complications related specifically to bag-in-the-lens IOL implantation technique shall to be considered during the learning curve.

Great clinical variability of Nance Horan syndrome due to deleterious NHS mutations in two unrelated Spanish families

Background: Nance-Horan syndrome (NHS) is an X-linked rare congenital disorder caused by mutations in the NHS gene. Clinical manifestations include congenital cataracts, facial and dental dysmorphism and, in some cases, intellectual disability. The aim of the present work was to identify the genetic cause of this disease in two unrelated Spanish NHS families and to determine the relative involvement of this gene in the pathogenesis.Materials and methods: Four members of a two-generation family, three males and one female (Family 1), and seven members of a three-generation family, two males and five females (Family 2) were recruited and their index cases were screened for mutations in the NHS gene and 26 genes related with ocular congenital anomalies by NGS (Next Generation Sequencing).Results: Two pathogenic variants were found in the NHS gene: a nonsense mutation (p.Arg373X) and a frameshift mutation (p.His669ProfsX5). These mutations were found in the two unrelated NHS families with different clinical manifestations.Conclusions: In the present study, we identified two truncation mutations (one of them novel) in the NHS gene, associated with NHS. Given the wide clinical variability of this syndrome, NHS may be difficult to detect in individuals with subtle clinical manifestations or when congenital cataracts are the primary clinical manifestation which makes us suspect that it can be underdiagnosed. Combination of genetic studies and clinical examinations are essential for the clinical diagnosis optimization.

Comparison of Manual Capsulorhexis and 25-Gauge Vitrectorhexis in Pediatric Cataract Surgery: A Pilot Study

PURPOSE

To compare short-term visual outcomes (best corrected visual acuity [BCVA]), visual axis opacification, anterior (ACCC) and posterior (PCCC) continuous curvilinear capsulorhexis size, shape, and extension, and their decentration between manual capsulorhexis and 25-gauge vitrectorhexis in pediatric cataract surgery with intraocular lens (IOL) implantation.

METHODS

Thirty eyes of children aged 3 to 8 years with developmental cataract were randomly selected for ACCC and PCCC by manual capsulorhexis forceps and 25-gauge vitrectomy cutter followed by IOL implantation and limited anterior vitrectomy. The size of the ACCC and PCCC was measured intraoperatively with calibrated capsulorhexis forceps. Patients were followed up for 3 months postoperatively and were evaluated for BCVA and visual axis opacification. Slit-lamp photographs of operated eyes were taken in retroillumination. The size in millimeters and decentration of the ACCC and PCCC from the center of the IOL were measured with the help of the Python imaging library.

RESULTS

There was no statistically significant difference between BCVA (P > .05), visual axis opacification (P > .05), size of the ACCC (P > .05) and its decentration (P > .05), extension of the rhexis (P > .05), and size of the PCCC (P > .05) and its decentration (P > .05) between the two methods.

CONCLUSIONS

In both groups, BCVA, visual axis opacification, and ACCC and PCCC size, shape, and decentration from the center of the IOL were comparable, making 25-gauge vitrectorhexis a good alternative to manual capsulorhexis. [J Pediatr Ophthalmol Strabismus. 2019;56(5):327-332.].

Epithelial-Mesenchymal Transdifferentiation in Pediatric Lens Epithelial Cells

Purpose

Posterior capsule opacification (PCO) is a complication after cataract surgery, particularly in children. Epithelial-mesenchymal transition (EMT) of lens epithelial cells, mediated by transforming growth factor beta (TGFβ), contributes to PCO. However, its pathogenesis in children is poorly understood. We correlated cell growth in culture with patient characteristics, studied gene expression of pediatric lens epithelial cells (pLEC), and examined the effects of TGFβ-2 on these cells in vitro.

Methods

Clinical characteristics of children with cataracts correlated with growth behavior of pLEC in vitro. mRNA expression of epithelial (αB-crystallin, connexin-43) and mesenchymal (αV-integrin, α-smooth muscle actin, collagen-Iα2, fibronectin-1) markers was quantified in pLEC and in cell line HLE-B3 in the presence and absence of TGFβ-2.

Results

Fifty-four anterior lens capsules from 40 children aged 1 to 180 months were obtained. Cell outgrowth occurred in 44% of the capsules from patients ≤ 12 months and in 33% of capsules from children aged 13 to 60 months, but in only 6% of capsules from children over 60 months. TGFβ-2 significantly upregulated expression of αB-crystallin (HLE-B3), αV-integrin (HLE-B3), collagen-Iα2, and fibronectin-1 (in pLEC and HLE-B3 cells).

Conclusions

Patient characteristics correlated with growth behavior of pLEC in vitro, paralleling a higher clinical incidence of PCO in younger children. Gene expression profiles of pLEC and HLE-B3 suggest that upregulation of αV-integrin, collagen-Iα2, and fibronectin-1 are involved in EMT.

The role of primary intraocular lens implantation in the risk of secondary glaucoma following congenital cataract surgery: A systematic review and meta-analysis

Objective

This meta-analysis aims to evaluate the incidence of secondary glaucoma in patients under the age of 2 years who underwent congenital cataract surgery with or without primary intraocular lens (IOL) implantation.

Methods

An electronic literature search was performed in Medline, EMBASE, and Web of Science databases to retrieve studies between January 2011 and November 2018. Patients with congenital cataract who did primary IOL implantation, aphakia, or secondary IOL implantation followed by receiving extraction surgery were included in this study. Relevant studies meeting defined eligibility criteria were selected and reviewed systematically by meta-analysis. Long-term incidences of secondary glaucoma, which developed at least one year after cataract surgery, were considered and discussed as clinical outcomes in each cohort. The pooled data were analyzed according to a random effects model.

Results

Eight publications involving 892 eyes were included in the current meta-analysis. In the general population of eyes with congenital cataract, the long-term incidence of secondary glaucoma was lower (P = 0.06) in eyes with primary IOL (9.5%) than in eyes without primary IOL (15.1%), including aphakia and secondary IOL. The pooled risk ratio (RR) favors primary IOL implantation in all patients (RR = 0.63). For bilateral congenital cataract, the incidence was 6.7% in eyes with primary IOL implantation, which is significantly lower than the 16.7% in eyes with aphakia and secondary IOL implantation (P<0.05, RR = 0.44). However, for unilateral congenital cataract surgery, the incidence was very similar in eyes with and without primary IOL (12.4% vs 12.0%, P = 0.61, RR = 0.87).

Conclusions

In patients under 2 years of age, primary IOL implantation for bilateral congenital cataract surgery is associated with a lower risk of secondary glaucoma.

Outcomes of cataract surgery in Microophthalmia

Objective

To find out outcomes of cataract surgery with Microophthalmia in children less than two years.

Methods

This cross-sectional study was conducted at Al-Ibrahim Eye Hospital, Karachi from January 2016 to August 2017. It included thirty micro ophthalmic eyes of infants with visually significant cataract of age less than two years who had cataract surgery without intraocular lens implantation. Axial length of globe was 19 mm or less in all thirty eyes of seventeen infants. in which thirteen infants had bilateral cataract and four had unilateral cataract.

Result

Thirty Simple Micro ophthalmic eyes from seventeen patients having visually significant congenital cataract were studied. Thirteen had bilateral cataract and four had unilateral cataract. Mean preoperative IOP was 9.0±1.2 mmHg and postoperative IOP after three months was 10.9±3.2 mmHg. Three patients had secondary capsular opacification 17.6%. Two patients had posterior synachae 11.8% after three months.

Conclusion

The results suggest that cataract surgery in simple microophthalmia is safe procedure. Postoperative complications in this study were within acceptable limits. Long term study with intraocular lens is required to confirm our observation.

A follow-on study on vision-related quality of life assessment using the NEI-VFQ-25 in those with a history of unilateral and bilateral congenital cataracts

PURPOSE

To assess vision-specific health-related quality of life (using the NEI-VFQ-25), educational attainment and visual acuity (VA) in patients with a history of congenital cataracts and appraise these in relation to Kirwan et al.'s (Pediatr Ophthalmol Strabismus 49, 2012, 26) study.

METHODS

A retrospective hospital-based study of patients with unilateral and bilateral congenital cataracts whounderwent surgery aged younger than 12 months. Those 13 years or older at follow-up were selected for inclusion. Patients with glaucoma, other associated ocular complications or systemic abnormalities were excluded. Educational attainment and VA at latest review were recorded.

RESULTS

Twelve patients with unilateral cataract (mean age: 26 ± 4.5) and fifteen with bilateral cataract (mean age 22 ± 4.3) were included. Bilateral group had greater difficulty with near and distance activities, vision-specific role difficulties, vision-specific dependency and general health than the unilateral group. There were no significant differences with regard to ocular pain, vision-specific social functioning, vision-specific mental health, driving, colour vision, peripheral vision or educational attainment between the groups. All patients attended mainstream school, and majority progressed to third-level education. Follow up at an increased time from surgery - 6.2 ± 5.13 (unilateral) and 6.5 ± 6.4 years (bilateral) - compared to Kirwan et al.'s study.

CONCLUSION

Results were in keeping with Kirwan et al.'s. Bilateral group had greater difficulty with day-to-day tasks compared to the unilateral group, including near and distance vision activities. They had greater vision-specific role difficulties and vision-specific dependency. There was no difference between the groups in regard to vision-specific social functioning, vision-specific mental health or educational attainment. This can be a source of reassurance to parents and patients.

Radiation-induced Cataracts in Children With Brain Tumors Receiving Craniospinal Irradiation

Radiation is a well-known cause of the development of cataracts. For children with brain tumors, craniospinal irradiation (CSI) would be expected to result in a significant risk of cataract development. We reviewed the incidence of cataracts in children with brain tumors who received CSI at our institution. Of 45 children who received CSI and had ophthalmologic examinations, 13 developed cataracts. The median time to develop cataracts was 27.6 months. Seven children underwent surgery for cataract. Given this high incidence of cataracts, we suggest routine eye examinations for all children receiving CSI.

Electron microscopic evaluation of anterior lens epithelium in patients with idiopathic congenital cataract

PURPOSE

To investigate the ultrastructure of the lens epithelial cells (LECs) in patients with idiopathic congenital cataract.

METHODS

This is a prospective interventional study. The anterior lens capsules (aLC: basement membrane and associated LECs) were taken from 16 eyes of 12 consecutive patients who were diagnosed as having idiopathic congenital cataracts. The aLCs were obtained from cataract surgery and prepared for transmission electron microscopy (TEM).

RESULTS

Some significant ultrastructural changes were observed in all aLCs of the participants. The anterior LECs showed alterations in different areas which were partly cuboidal and partly squamous in shape. The LECs had euchromatic nucleus and included some vacuoles in the cytoplasms as a remarkable alteration. The sizes of these intraepithelial cell vacuoles were changeable.

CONCLUSIONS

We identified remarkable changes in LECs of the eyes with idiopathic congenital cataract by TEM. It can be assumed that oxidative damage may be associated with these ultrastructural changes in LECs of the eyes with idiopathic congenital cataracts.

Clinical Features of Congenital and Developmental Cataract in East China: A Five-year Retrospective Review

Congenital/developmental cataract is a significant cause of blindness in children worldwide. Full knowledge of clinical features is essential for early diagnosis and proper treatment to prevent irreversible visual impairment. We conducted a retrospective chart review on 520 congenital/developmental cataract cases based on a five-year clinical data from Eye and ENT Hospital of Fudan University, Shanghai, China. Clinical features including age at the surgery, chief complaints, interval between initial identification of cataract-related manifestations and surgery, etc. were summarized. 56.3% of children were bilateral. The age at surgery ranged from 0.25 to 17.4 years, only 9.2% receiving surgery below 1 year. Interval between initial identification of manifestations and surgery ranged from 2 days to 17 years. Concomitant congenital abnormalities were present in 67 patients, with persistent hyperplastic primary vitreous and congenital heart disease as the most frequent ocular and systemic disorders. Strabismus and nystagmus were seen in 20.6% and 11.9% of patients. In bilateral cataract patients with strabismus, axial lengths of esotropia-affected eyes were statistically shorter than exotropia-affected eyes. These findings provide information on characteristics of congenital/developmental cataract in China and may assist in achievement of comprehensive treating strategies in these cases.

Identification of a Novel Mutation in BRD4 that Causes Autosomal Dominant Syndromic Congenital Cataracts Associated with Other Neuro-Skeletal Anomalies

Congenital cataracts can occur as a non-syndromic isolated ocular disease or as a part of genetic syndromes accompanied by a multi-systemic disease. Approximately 50% of all congenital cataract cases have a heterogeneous genetic basis. Here, we describe three generations of a family with an autosomal dominant inheritance pattern and common complex phenotypes, including bilateral congenital cataracts, short stature, macrocephaly, and minor skeletal anomalies. We did not find any chromosomal aberrations or gene copy number abnormalities using conventional genetic tests; accordingly, we conducted whole-exome sequencing (WES) to identify disease-causing genetic alterations in this family. Based on family WES data, we identified a novel BRD4 missense mutation as a candidate causal variant and performed cell-based experiments by ablation of endogenous BRD4 expression in human lens epithelial cells. The protein expression levels of connexin 43, p62, LC3BII, and p53 differed significantly between control cells and cells in which endogenous BRD4 expression was inhibited. We inferred that a BRD4 missense mutation was the likely disease-causing mutation in this family. Our findings may improve the molecular diagnosis of congenital cataracts and support the use of WES to clarify the genetic basis of complex diseases.

Anesthetic dilemma in planning bilateral cataract surgery for an infant associated with congenital cardiac anomaly

In a patient with tetralogy of Fallot (TOF) and pulmonary atresia, treating the cardiac problem or the associated congenital illness is always a challenge. We describe the challenges and successful initial management of bilateral cataract to prevent visual loss in an infant with TOF with pulmonary atresia.

Clinical characteristics of congenital and developmental cataract undergoing surgical treatment

PURPOSE

To analyze the clinical characteristics of congenital/developmental cataract undergoing surgery.

METHODS

A mail questionnaire was sent to 49 facilities engaged in surgical treatment of congenital cataracts, and data on preoperative clinical features were collected.

RESULTS

Twenty nine facilities reported on 864 eyes of 521 patients with congenital/infantile cataract, ranging in age at initial visit from 0 to 18.8 years (2.6 ± 3.3 years, mean ± standard deviation). Among the patients, 65.8 % had bilateral cataracts and 34.2 % were unilaterally affected. Family history was found for 22.4 % of cases, of which 98.1 % were bilateral. Family history was positive for 33.1 % of bilateral and 1.3 % of unilateral cases. The most common main complaint was white pupil for 35.7 % of bilateral cases and 32.7 % for unilateral cases. Concomitant systemic abnormalities were more frequently associated with bilateral cases (31.6 %) than with unilateral cases (16.7 %). Associated ocular diseases, such as strabismus, persistent fetal vasculature, and posterior lenticonus, were more frequently seen among unilateral cases whereas nystagmus was more common among bilateral cases.

CONCLUSIONS

Among congenital/developmental cataracts, the ratio of bilateral and unilateral cases was approximately 2:1. Almost all patients with a family history of congenital cataract were bilateral. Initial visits to a physician were rather late, 2.6 years from birth; this should be improved.

Pediatric cataract: challenges and future directions

Cataract is a significant cause of visual disability in the pediatric population worldwide and can significantly impact the neurobiological development of a child. Early diagnosis and prompt surgical intervention is critical to prevent irreversible amblyopia. Thorough ocular evaluation, including the onset, duration, and morphology of a cataract, is essential to determine the timing for surgical intervention. Detailed assessment of the general health of the child, preferably in conjunction with a pediatrician, is helpful to rule out any associated systemic condition. Although pediatric cataracts have a diverse etiology, with the majority being idiopathic, genetic counseling and molecular testing should be undertaken with the help of a genetic counselor and/or geneticist in cases of hereditary cataracts. Advancement in surgical techniques and methods of optical rehabilitation has substantially improved the functional and anatomic outcomes of pediatric cataract surgeries in recent years. However, the phenomenon of refractive growth and the process of emmetropization have continued to puzzle pediatric ophthalmologists and highlight the need for future prospective studies. Posterior capsule opacification and secondary glaucoma are still the major postoperative complications necessitating long-term surveillance in children undergoing cataract surgery early in life. Successful management of pediatric cataracts depends on individualized care and experienced teamwork. We reviewed the etiology, preoperative evaluation including biometry, choice of intraocular lens, surgical techniques, and recent developments in the field of childhood cataract.

Mutation of the melastatin-related cation channel, TRPM3, underlies inherited cataract and glaucoma

Inherited forms of cataract are a clinically important and genetically heterogeneous cause of visual impairment that usually present at an early age with or without systemic and/or other ocular abnormalities. Here we have identified a new locus for inherited cataract and high-tension glaucoma with variable anterior segment defects, and characterized an underlying mutation in the gene coding for transient receptor potential cation channel, subfamily M, member-3 (TRPM3, melastatin-2). Genome-wide linkage analysis mapped the ocular disease locus to the pericentric region of human chromosome 9. Whole exome and custom-target next-generation sequencing detected a heterozygous A-to-G transition in exon-3 of TRPM3 that co-segregated with disease. As a consequence of alternative splicing this missense mutation was predicted to result in the substitution of isoleucine-to-methionine at codon 65 (c.195A>G; p.I65 M) of TRPM3 transcript variant 9, and at codon 8 (c.24A>G; p.I8 M) of a novel TRPM3 transcript variant expressed in human lens. In both transcript variants the I-to-M substitution was predicted in silico to exert damaging effects on protein function. Furthermore, transient expression studies of a recombinant TRPM3-GFP reporter product predicted that the I-to-M substitution introduced an alternative translation start-site located 89 codons upstream from the native initiator methionine found in eight other TRPM3 transcript variants (1-8). Collectively, these studies have provided the first evidence that TRPM3 is associated with inherited ocular disease in humans, and further provide support for the important role of this cation channel in normal eye development.

Factors associated with strabismus after cataract extraction and primary intraocular lens implantation in congenital cataracts

AIM

To evaluate factors associated with the development of strabismus after cataract extraction and primary intraocular lens implantation.

METHODS

The medical records of 122 patients, aged 1.5mo to 9y, who had undergone cataract extraction with primary intraocular lens implantation between January 1993 and August 2011 were reviewed. Fourteen patients (17 eyes) with strabismus before cataract surgery were excluded. Patients were divided into those with congenital bilateral cataracts (64 patients, 128 eyes) and those with unilateral cataracts (44 patients, 44 eyes). The associations between the development of strabismus and age at cataract surgery, pre- and post-cataract extraction corrected distance visual acuity (CDVA), interocular CDVA difference, nystagmus, surgical method, and secondary cataract were evaluated.

RESULTS

Factors significantly associated with the development of strabismus included age at cataract surgery (≤1y), preoperative mean CDVA ≤20/100, presence of nystagmus in the bilateral cataract group and postoperative interocular CDVA difference >20/70 in the unilateral group. Postoperative CDVA ≤20/100 and preservation of posterior capsule, and presence of secondary cataract were significant factors in both groups.

CONCLUSION

Children with congenital cataracts should be monitored carefully after cataract surgery for the development of strabismus, especially when they underwent surgery at age ≤1y, and they have nystagmus, large postoperative interocular CDVA difference, poor preoperative and postoperative CDVA, preservation of the posterior capsule, or secondary cataract.

Molecular genetics of congenital nuclear cataract

A cataract is defined as opacification of the normally transparent crystalline lens. Congenital cataract (CC) is a type of cataract that presents at birth or during early childhood. CC is one of the most common causes of visual impairment or blindness in children worldwide. Approximately 50% of all CC cases may have a genetic cause which is quite heterogeneous. CC occurs in a variety of morphologic configurations, including polar/subcapsular, nuclear, lamellar, sutural, cortical, membranous/capsular and complete. Nuclear cataract refers to the opacification limited to the embryonic and/or fetal nuclei of the lens. Although congenital nuclear cataract can be caused by multiple factors, genetic mutation remains to be the most common cause. It can be inherited in one of the three patterns: autosomal dominant, autosomal recessive, or X-linked transmission. Autosomal dominant inheritance is the most frequent mode with high penetrance. There may be no obvious correlation between the genotype and phenotype of congenital nuclear cataract. Animal models have been established to study the pathogenesis of congenital nuclear cataract and to identify candidate genes. In this review, we highlight identified genetic mutations that account for congenital nuclear cataract. Our review may be helpful for genetic counseling and prenatal diagnosis.

Cataracts among adults aged 30 to 49 years: a 10-year study from 1995 to 2004 in Korea

Purpose

To investigate the long-term characteristics of cataracts among adults aged 30 to 49 years in Korean over a span of 10 years.

Methods

Subjects between the ages of 30 to 49 years who underwent cataract surgery at St. Mary's Hospital from 1995 to 2004 (n = 976) were included. Patients with a history of ocular trauma, uveitis, other ocular or systemic diseases, and congenital cataracts were excluded. Additional information including type of lens opacity, urban/rural region, and pre- and postoperative visual acuities were analyzed. Lens opacity grading was conducted using Lens Opacity Classification System III. The Cochran-Armitage proportion trend test was used to analyze vision changes with the passage of time.

Results

Among the patients who had undergone cataract surgeries, 8.8% (976 / 11,111) met the inclusion criteria. The mean age was 41.7 ± 5.45 years. Gender breakdown of the patient population included 79.0% male and 21.0% female. In terms of home environment, 60.9% were from an urban region and 39.1% from a rural region. Opacity type included anterior polar (AP), posterior subcapsular (PSC), AP and PSC, cortical, and nuclear in 35.7%, 35.1%, 7.0%, 6.0%, and 5.4% of patients, respectively. At a 2-month postoperative follow-up appointment, 92.7% of patients showed a best-corrected visual acuity of more than 20 / 40.

Conclusions

Predominance of AP and PSC opacities as well as male patients was observed in this study population.

Management and outcomes of cataract in children: the Toronto experience

PURPOSE

To review the management and outcomes of pediatric patients with cataract who were managed by one of two surgeons at a single institution.

METHODS

An observational series of consecutive cases identified from the hospital's outpatient billing records and surgical data program were used. Visual acuity was measured with the Snellen or Allen charts. Glaucoma was defined as IOP >20 mm Hg with clinical signs of glaucoma or visual field loss. Procedures for aphakic/pseudophakic glaucoma were excluded from analysis of additional surgeries performed subsequent to cataract extraction.

RESULTS

The search identified 778 patients (1,122 eyes) diagnosed with cataract over 10 years. Of these, 74% of eyes were treated surgically. Those patients with total, nuclear, and lamellar cataracts were significantly more likely than the overall population to undergo surgery. Additional surgeries were required in 12% of surgically treated eyes, with pseudophakic eyes representing more than one-half. Aphakic and pseudophakic glaucoma prevalence were 12% and 1%, respectively. Cataract morphology was not found to be a predisposing factor in the development of glaucoma. Visual outcomes were significantly better for posterior subcapsular (P = 0.0001), nuclear (P = 0.025), lamellar (P = 0.03), and traumatic cataracts (P = 0.005) than for other morphological types at all ages. Visual acuity was 20/30 or better in 63% of children with unilateral pseudophakia, 45% of children with unilateral aphakia, and approximately 75% of children with bilateral aphakia and pseudophakia.

CONCLUSIONS

Patients with total, nuclear, and lamellar cataracts were more likely to undergo surgery. Approximately 10% of patients required additional surgeries. No cataract morphology predisposed patients to developing glaucoma. Good visual outcomes were attained in bilaterally pseudophakic/aphakic and unilaterally pseudophakic children.

Long-term outcome of primary versus secondary intraocular lens implantation after simultaneous removal of bilateral congenital cataract

BACKGROUND

Long-term outcomes of intraocular lens (IOL) implantation for congenital cataract in children under 2 years old are still undetermined.

METHODS

We retrospectively reviewed all cases of bilateral congenital cataract who had undergone simultaneous bilateral cataract removal with posterior capsulotomy and central anterior vitrectomy between 1990 and 2010. Patients randomly underwent primary IOL implantation or secondary IOL implantation after a period of contact lens wear. The two groups were compared for visual outcome and complications during follow-up.

RESULTS

Cataract removal and primary IOL implantation was performed in 30 eyes (15 patients; nine males, six females) at a mean age of 6.8 ± 4.2 months. After 79.31 ± 63.4 months, best-corrected visual acuity (BCVA) was 0.53 ± 0.36 EDTRS LogMAR. In 36 eyes (18 patients, 11 males, seven females) the lens was removed at a mean age of 5.42 ± 2.80 months, and after 32.0 ± 6.1 months of contact lens utilization, secondary IOL implantation was performed. After 109.0 ± 33.8 months, BCVA was 0.54 ± 0.4 ETDRS LogMAR. The association between age at surgery and final visual acuity and the difference between the two groups concerning type of cataract at baseline, BCVA and refractive error at last visit, incidence of posterior capsular opacification, glaucoma, strabismus, and nystagmus during follow-up were not significant (p > 0.05). Myopic shift was more frequent in eyes undergone primary IOL implantation (p < 0.001).

CONCLUSIONS

Similar visual outcome and complications were observed during long-term follow-up after both primary and secondary IOL implantation following simultaneous bilateral congenital cataract removal with posterior capsulotomy and central anterior vitrectomy.

Long-term visual acuity and initial postoperative refractive error in pediatric pseudophakia

OBJECTIVE

To examine the long-term best-corrected visual acuity (BCVA) in children who, during the amblyogenic period, underwent cataract extraction with intraocular lens (IOL) implantation and to see if initial postoperative refractive error following cataract extraction correlates with long-term BCVA.

DESIGN

Retrospective chart review.

PARTICIPANTS

Thirty-six eyes of 26 patients were included in the study. At least 2 years of follow-up, an age , 8.5 years at time of IOL implantation, an ability to participate in subjective visual acuity measurement, and an absence of congenital glaucoma and significant trauma were required for inclusion in the study.

METHODS

Retrospective review of pseudophakic patients' charts at a tertiary care centre, with attention to initial and long-term pseudophakic refractive error, long-term BCVA, total myopic shift, length of follow-up, age at IOL implantation, and unilateral or bilateral cataract extraction with IOL implantation.

RESULTS

Initial pseudophakic spherical equivalent (SE) showed a significant nonlinear relationship with most recentBCVAin unilateral cases and no relationship in bilateral cases (interaction p 0.001). Unilateral cases with initial pseudophakic SE between +1.75 D and +5.00 D showed better long-term BCVA than those with values below +1.75 D or above +5.00 D; this was irrespective of the refractive error of their fellow eye.

CONCLUSIONS

In patients receiving lens implants in the first 8 years of life, we recommend aiming for low early postoperative hyperopia, taking into consideration each patient's situation and age.

Increased hydrophobicity and decreased backbone flexibility explain the lower solubility of a cataract-linked mutant of γD-crystallin

A number of point mutations in γD-crystallin are associated with human cataract. The Pro23-to-Thr (P23T) mutation is perhaps the most common, is geographically widespread, and presents itself in a variety of phenotypes. It is therefore important to understand the molecular basis of lens opacity due to this mutation. In our earlier studies, we noted that P23T shows retrograde and sharply lowered solubility, most likely due to the emergence of hydrophobic patches involved in protein aggregation. Binding of 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonate (Bis-ANS) dye (a probe commonly used for detecting surface hydrophobicity) competed with aggregation, suggesting that the residues involved in Bis-ANS binding are also involved in protein aggregation. Here, using NMR spectroscopy in conjunction with Bis-ANS binding, we identify three residues (Y16, D21, and Y50) in P23T that are involved in binding the dye. Furthermore, using (15)N NMR relaxation experiments, we show that, in the mutant protein, backbone fluctuations are restricted to the picosecond-to-nanosecond and microsecond timescales relative to the wild type. Our present studies specify the residues involved in these two pivotal characteristics of the mutant protein, namely increased surface hydrophobicity and restricted mobility of the protein backbone, which can explain the nucleation and further propagation of protein aggregates. Thus, we have now identified the residues in the P23T mutant that give rise to novel hydrophobic surfaces, as well as those regions of the protein backbone where fluctuations in different timescales are restricted, providing a comprehensive understanding of how lens opacity could result from this mutation.

Clinical and experimental advances in congenital and paediatric cataracts

Cataracts (opacities of the lens) are frequent in the elderly, but rare in paediatric practice. Congenital cataracts (in industrialized countries) are mainly caused by mutations affecting lens development. Much of our knowledge about the underlying mechanisms of cataractogenesis has come from the genetic analysis of affected families: there are contributions from genes coding for transcription factors (such as FoxE3, Maf, Pitx3) and structural proteins such as crystallins or connexins. In addition, there are contributions from enzymes affecting sugar pathways (particularly the galactose pathway) and from a quite unexpected area: axon guidance molecules like ephrins and their receptors. Cataractous mouse lenses can be identified easily by visual inspection, and a remarkable number of mutant lines have now been characterized. Generally, most of the mouse mutants show a similar phenotype to their human counterparts; however, there are some remarkable differences. It should be noted that many mutations affect genes that are expressed not only in the lens, but also in tissues and organs outside the eye. There is increasing evidence for pleiotropic effects of these genes, and increasing consideration that cataracts may act as early and readily detectable biomarkers for a number of systemic syndromes.

Molecular characteristics of inherited congenital cataracts

Congenital cataracts are a major cause of induced blindness in children, and inherited cataracts are the major cause of congenital cataracts. Inherited congenital cataracts have been associated with mutations in specific genes, including those of crystallins, gap junction proteins, membrane transport and channel proteins, the cytoskeleton, and growth and transcription factors. Locating and identifying the genes and mutations involved in cataractogenesis are essential to gaining an understanding of the molecular defects and pathophysiologic characteristics of inherited congenital cataracts. In this review, we summarize the current research in this field.