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Central Corneal Thickness in Children with Glaucoma or at Risk for Glaucoma
88
Abstracts
High-Resolution Magnetic Resonance Imaging (MRI) Quantifies Oculomotor Nerve (CN3) Size in Congenital Neuropathic Strabismus Key Hwan Lim1, Elizabeth C. Engle3, Joseph L. Demer1,2; 1Jules Stein Eye Institute, and 2Department of Neurology, David Geffen Medical School, University of California, Los Angeles, CA; 3Children’s Hospital Boston and Harvard Medical School, Boston, MA Introduction: High-resolution MRI can now directly demonstrate innervation to extraocular muscles and quantify optic nerve size. We developed a quantitative MRI technique to study CN3 and applied it to congenital fibrosis of extraocular muscles (CFEOM), congenital oculomotor palsy, and Duanes retraction syndrome (DRS). Methods: Oculomotor nerves were imaged at the brainstem using a 1.5-T scanner and conventional head coils, acquiring heavily T2-weighted oblique axial MRI planes 1 mm thick parallel to the optic chiasm. We investigated 13 normal subjects, 10 subjects with DRS, 7 with CFEOM, and 3 with congenital CN3 palsy. Digital image analysis was used to measure CN3 diameter, which was correlated with motility findings. Results: CN3 was bilaterally hypoplastic in five patients with CFEOM. Mean (⫾SD) CN3 diameter in CFEOM was 1.11 ⫾ 0.79 mm, significantly smaller than normal diameter of 2.01 ⫾ 0.36 mm (P ⬍ 0.05). CN3 size variably correlated with clinical function. Mean CN3 diameter in congenital CN3 palsy was subnormal at 1.28 ⫾ 0.46 mm. One patient with DRS showed unilateral CN3 hypoplasia. Mean CN3 diameter in DRS was 1.78 ⫾ 0.52 mm, slightly but not significantly subnormal. Conclusion: CN3 hypoplasia is quantitatively demonstrable using conventional MRI equipment in several forms of congenital neuropathic strabismus, including CFEOM and oculomotor palsy, and occasionally occurs in DRS. Quantitative, high-resolution MRI might be useful to clarify mechanisms of strabismus in clinically uncertain cases. Reference: Karim S, et al. Demonstration of systematic variation in human intraorbital optic nerve size by quantitative magnetic resonance imaging and histology. Invest Ophthalmol Vis Sci 2004;45;1047-51. The Effect of Laryngeal Mask Airway Insertion on Intraocular Pressure Measurement in Children Under General Anesthesia May K. Lim MRCOphth,1 Patrick O. Watts MBBS, MS, FRCS, FRCOphth,2 Achyut Mukherjee MRCOphth,1 Trevor Armstrong,2 Rhys Jones,2 Tazin Zatman2; 1Cardiff Eye Unit, University Hospital of Wales, Cardiff, South Glamorgan, UK; 2Department of Anesthesia, University Hospital of Wales, Cardiff, South Glamorgan, UK Purpose: We aim to study the change in intraocular pressure (IOP) in children under general anesthesia, before and after laryngeal mask airway (LMA) insertion. From this we aim to recommend the optimal timing of performing IOP measurements in these cases. Method: Intraocular pressure was measured in children after induction and 1 minute after LMA insertion. Children (age ⬍16) scheduled to undergo elective ophthalmic surgery under a general anesthetic were included. Children with a history of glaucoma or previous intraocular surgery were excluded. Data were collected on the age of the child, the IOP, heart rate (HR), end-tidal CO2, and blood pressure (BP), before and after LMA insertion. Results: Seventyseven children with a mean age of 5 ⫾ 3.5 years (range: 4 months to 13 years) were included in the study. The mean IOP was 13.5 ⫾ 4.0 and 13.8 ⫾ 4.6 mm Hg prior to LMA insertion and 15.5 ⫾ 4.0 and 15.5 ⫾ 4.8 mm Hg after insertion of the mask in the right and left eye, respectively (P ⫽ 0.000). A change in BP was significantly associated with an increase in IOP (P ⫽ 0.007) and the interaction between the change in the BP, HR, and CO2 affected the change in IOP measured after insertion of the LMA (P ⫽ 0.01). Conclusion: In our study, a small but significantly higher IOP was found after LMA insertion than before. It is recommended that the measurement of IOP in children under general anesthesia be carried out before the insertion of the LMA.
Journal of AAPOS Volume 10 Number 1 February 2006 The Epidemiology of Pediatric Cataracts—The Toronto Experience Zena Lim, Shehla Rubab, David S. Rootman, Alex V. Levin; The Hospital for Sick Children, Toronto, Ontario, Canada Introduction: To better characterize the epidemiology and outcome related to pediatric cataracts and to compare the success of cataract surgery and visual prognosis between different subgroups. Methods: Retrospective review of all charts of children who presented at the Hospital for Sick Children, Toronto with cataracts from January 1992 to December 2002. Results/Discussion: Identified were 1122 eyes in 778 children; 44.5% of cases were bilateral. Posterior subcapsular cataract was the most common morphological form (37.2%), followed by dense (21.0%) and nuclear cataract (15.6%). The etiology was idiopathic in 30.5%, and 26.2% were associated with systemic disease. Down syndrome was the most common of cataract-associated syndromes. The median age at surgery was 36.0 months. Follow-up from time of surgery ranged from 0.03 to 180.0 months. In the group that underwent lens extraction and intraocular lens implantation, 54.0% achieved a final visual outcome of 6/9 or better. In the group that was left aphakic, 19.3% achieved a similar outcome with visual rehabilitation. Glaucoma developed in 13.0% of eyes that underwent cataract surgery. IOL implantation was associated with a lower incidence of glaucoma. The incidence of strabismus was lowest in the group of children with intraocular lens implantation and highest when contact lens was used for visual rehabilitation (P ⬍ 0.001). Eighty-seven cases (15.3%) required reoperation. There was no difference in the incidence of glaucoma between cases that required reoperation and cases that underwent surgery once. Conclusions: This study provides useful epidemiological data from a large, diverse population of children. It provides a better insight into the factors influencing treatment outcome. Central Corneal Thickness in Children with Glaucoma or at Risk for Glaucoma Juan P. Lopez MD, Alex V. Levin MD, MHSc, FRCSC, Sharon F. Freedman MD, Kelly W. Muir MD, Lois Duncan; The Hospital for Sick Children, Toronto, Ontario, Canada Introduction: Tonometry readings may be artificially high when central corneal thickness (CCT) is elevated and low when CCT is decreased.1 Little is known about CCT in pediatric glaucoma or eyes at risk for glaucoma (eg, aphakia, aniridia, uveitis).2 Methods: Children 18 years old were studied retrospectively and prospectively at The Hospital for Sick Children and Duke University from December 2003 to March 2005. CCT was obtained by ultrasound pachymetry awake or under general anesthesia/sedation. Results: Included were 332 eyes from 271 children [mean age 6.66 years (0.7 months to 17.9 years)]: 141 eyes (42.46%) with glaucoma, 76 (22.89%) at risk for glaucoma, 49 (14.75%) unaffected fellow eyes, and 66 (19.87%) control eyes. CCT was higher and Aphakic eyes had thickest corneas [CCT ⫽ 0.635 mm (0.387 to 0.850 mm)]. Using adult nomograms3 for adjusting IOP according to CCT, 69.87% of eyes adjusted downwards and 23.79% adjusted upwards. Of glaucoma and at risk eyes, 13.82% were adjusted below IOP ⫽ 21 and 1.38% were adjusted above, indicating a possible need for changing clinical management. As pediatric CCT values extend beyond the adult normogram, we present a new normogram for values in excess of 0.645. Discussion: This is the largest series of CCT in children with glaucoma or at risk for glaucoma. Our data suggest clinically significant adjustment of IOP may be needed in many children. References: 1. Whitacre MM, et al. Am J Ophthalmol 1993;115:592-6. 2. Hussein MA, et al. Am J Ophthalmol 2004;138:744-8. 3. Doughty MJ, et al. Surv Ophthalmol 2000;44(5): 367-408.
Abstracts
High-Resolution Magnetic Resonance Imaging (MRI) Quantifies Oculomotor Nerve (CN3) Size in Congenital Neuropathic Strabismus Key Hwan Lim1, Elizabeth C. Engle3, Joseph L. Demer1,2; 1Jules Stein Eye Institute, and 2Department of Neurology, David Geffen Medical School, University of California, Los Angeles, CA; 3Children’s Hospital Boston and Harvard Medical School, Boston, MA Introduction: High-resolution MRI can now directly demonstrate innervation to extraocular muscles and quantify optic nerve size. We developed a quantitative MRI technique to study CN3 and applied it to congenital fibrosis of extraocular muscles (CFEOM), congenital oculomotor palsy, and Duanes retraction syndrome (DRS). Methods: Oculomotor nerves were imaged at the brainstem using a 1.5-T scanner and conventional head coils, acquiring heavily T2-weighted oblique axial MRI planes 1 mm thick parallel to the optic chiasm. We investigated 13 normal subjects, 10 subjects with DRS, 7 with CFEOM, and 3 with congenital CN3 palsy. Digital image analysis was used to measure CN3 diameter, which was correlated with motility findings. Results: CN3 was bilaterally hypoplastic in five patients with CFEOM. Mean (⫾SD) CN3 diameter in CFEOM was 1.11 ⫾ 0.79 mm, significantly smaller than normal diameter of 2.01 ⫾ 0.36 mm (P ⬍ 0.05). CN3 size variably correlated with clinical function. Mean CN3 diameter in congenital CN3 palsy was subnormal at 1.28 ⫾ 0.46 mm. One patient with DRS showed unilateral CN3 hypoplasia. Mean CN3 diameter in DRS was 1.78 ⫾ 0.52 mm, slightly but not significantly subnormal. Conclusion: CN3 hypoplasia is quantitatively demonstrable using conventional MRI equipment in several forms of congenital neuropathic strabismus, including CFEOM and oculomotor palsy, and occasionally occurs in DRS. Quantitative, high-resolution MRI might be useful to clarify mechanisms of strabismus in clinically uncertain cases. Reference: Karim S, et al. Demonstration of systematic variation in human intraorbital optic nerve size by quantitative magnetic resonance imaging and histology. Invest Ophthalmol Vis Sci 2004;45;1047-51. The Effect of Laryngeal Mask Airway Insertion on Intraocular Pressure Measurement in Children Under General Anesthesia May K. Lim MRCOphth,1 Patrick O. Watts MBBS, MS, FRCS, FRCOphth,2 Achyut Mukherjee MRCOphth,1 Trevor Armstrong,2 Rhys Jones,2 Tazin Zatman2; 1Cardiff Eye Unit, University Hospital of Wales, Cardiff, South Glamorgan, UK; 2Department of Anesthesia, University Hospital of Wales, Cardiff, South Glamorgan, UK Purpose: We aim to study the change in intraocular pressure (IOP) in children under general anesthesia, before and after laryngeal mask airway (LMA) insertion. From this we aim to recommend the optimal timing of performing IOP measurements in these cases. Method: Intraocular pressure was measured in children after induction and 1 minute after LMA insertion. Children (age ⬍16) scheduled to undergo elective ophthalmic surgery under a general anesthetic were included. Children with a history of glaucoma or previous intraocular surgery were excluded. Data were collected on the age of the child, the IOP, heart rate (HR), end-tidal CO2, and blood pressure (BP), before and after LMA insertion. Results: Seventyseven children with a mean age of 5 ⫾ 3.5 years (range: 4 months to 13 years) were included in the study. The mean IOP was 13.5 ⫾ 4.0 and 13.8 ⫾ 4.6 mm Hg prior to LMA insertion and 15.5 ⫾ 4.0 and 15.5 ⫾ 4.8 mm Hg after insertion of the mask in the right and left eye, respectively (P ⫽ 0.000). A change in BP was significantly associated with an increase in IOP (P ⫽ 0.007) and the interaction between the change in the BP, HR, and CO2 affected the change in IOP measured after insertion of the LMA (P ⫽ 0.01). Conclusion: In our study, a small but significantly higher IOP was found after LMA insertion than before. It is recommended that the measurement of IOP in children under general anesthesia be carried out before the insertion of the LMA.
Journal of AAPOS Volume 10 Number 1 February 2006 The Epidemiology of Pediatric Cataracts—The Toronto Experience Zena Lim, Shehla Rubab, David S. Rootman, Alex V. Levin; The Hospital for Sick Children, Toronto, Ontario, Canada Introduction: To better characterize the epidemiology and outcome related to pediatric cataracts and to compare the success of cataract surgery and visual prognosis between different subgroups. Methods: Retrospective review of all charts of children who presented at the Hospital for Sick Children, Toronto with cataracts from January 1992 to December 2002. Results/Discussion: Identified were 1122 eyes in 778 children; 44.5% of cases were bilateral. Posterior subcapsular cataract was the most common morphological form (37.2%), followed by dense (21.0%) and nuclear cataract (15.6%). The etiology was idiopathic in 30.5%, and 26.2% were associated with systemic disease. Down syndrome was the most common of cataract-associated syndromes. The median age at surgery was 36.0 months. Follow-up from time of surgery ranged from 0.03 to 180.0 months. In the group that underwent lens extraction and intraocular lens implantation, 54.0% achieved a final visual outcome of 6/9 or better. In the group that was left aphakic, 19.3% achieved a similar outcome with visual rehabilitation. Glaucoma developed in 13.0% of eyes that underwent cataract surgery. IOL implantation was associated with a lower incidence of glaucoma. The incidence of strabismus was lowest in the group of children with intraocular lens implantation and highest when contact lens was used for visual rehabilitation (P ⬍ 0.001). Eighty-seven cases (15.3%) required reoperation. There was no difference in the incidence of glaucoma between cases that required reoperation and cases that underwent surgery once. Conclusions: This study provides useful epidemiological data from a large, diverse population of children. It provides a better insight into the factors influencing treatment outcome. Central Corneal Thickness in Children with Glaucoma or at Risk for Glaucoma Juan P. Lopez MD, Alex V. Levin MD, MHSc, FRCSC, Sharon F. Freedman MD, Kelly W. Muir MD, Lois Duncan; The Hospital for Sick Children, Toronto, Ontario, Canada Introduction: Tonometry readings may be artificially high when central corneal thickness (CCT) is elevated and low when CCT is decreased.1 Little is known about CCT in pediatric glaucoma or eyes at risk for glaucoma (eg, aphakia, aniridia, uveitis).2 Methods: Children 18 years old were studied retrospectively and prospectively at The Hospital for Sick Children and Duke University from December 2003 to March 2005. CCT was obtained by ultrasound pachymetry awake or under general anesthesia/sedation. Results: Included were 332 eyes from 271 children [mean age 6.66 years (0.7 months to 17.9 years)]: 141 eyes (42.46%) with glaucoma, 76 (22.89%) at risk for glaucoma, 49 (14.75%) unaffected fellow eyes, and 66 (19.87%) control eyes. CCT was higher and Aphakic eyes had thickest corneas [CCT ⫽ 0.635 mm (0.387 to 0.850 mm)]. Using adult nomograms3 for adjusting IOP according to CCT, 69.87% of eyes adjusted downwards and 23.79% adjusted upwards. Of glaucoma and at risk eyes, 13.82% were adjusted below IOP ⫽ 21 and 1.38% were adjusted above, indicating a possible need for changing clinical management. As pediatric CCT values extend beyond the adult normogram, we present a new normogram for values in excess of 0.645. Discussion: This is the largest series of CCT in children with glaucoma or at risk for glaucoma. Our data suggest clinically significant adjustment of IOP may be needed in many children. References: 1. Whitacre MM, et al. Am J Ophthalmol 1993;115:592-6. 2. Hussein MA, et al. Am J Ophthalmol 2004;138:744-8. 3. Doughty MJ, et al. Surv Ophthalmol 2000;44(5): 367-408.