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Resident’s Day Poster Submission First Author: Elsa Sheerer, OD* Second Author: Noelda Fernandes, OD* *Pediatric Optometry Resident, 2015-16, SUNY College of Optometry Title (max 150 characters): Optometric examination and Management in Rett Syndrome Abstract (max 35 words): A nine year old Hispanic female with Rett Syndrome (RS) presents to the University Eye Center. Responses to visual stimuli are inconsistent, prompting electrodiagnostic testing to determine potential visual function. Ocular Manifestations in RS are discussed. I. Case History Patient demographics: 9 year old Hispanic female with history of Rett Syndrome (RS) Chief complaint: left visual field preference and prefers visually attending to real objects rather than pictorial representations Ocular history: bilateral eye muscle surgery for intermittent esotropia at age 6 Medical history: (+) Rett Syndrome; patient is non verbal and wheelchair bound. Exhibits continuous involuntary movement of limbs, head, and trunk. Difficulty with eating due to constant movement (+)seizures Medications: -- Trihexiphenidyl -- Kepra -- Triolepto -- Clonidine Allergies: none, No Known Medical Allergies Other salient information: Attending a school for children with Traumatic Brain Injury (TBI) for 1 year receiving Speech Therapy, Physical Therapy, Occupational Therapy receiving vision rehabilitation with an aid specializing in educational visual needs. per aid, child can visually track bright, shiny objects. per aid, child responds better to high contrast pictures Child's visual needs include: -- looking at Mayer-Johnson communication symbols used to communicate. -- food for eating. Developmental history: -- Full term pregnancy -- No complications during pregnancy or birth. II. Pertinent findings Clinical Visual acuity OD/OS: fix and follow at times with transilluminator. Child does not pick up fixation with any consistency. Eye movements are erratic. Visual field: inconclusive OD/OS EOMs: full, a lot of head movement Pupils: PERRL (-)APD Retinoscopy: OD: +1.00 sph OS: +1.00 sph Hand held slit lamp biomicorosocpy: Adnexa: normal OD/OS Eye lids and lashes: normal, good apposition, OD/OS Conjunctiva: white and quiet OD/OS Cornea: clear, normal endothelial, epithelial, stroma and tear film OD/OS Iris: flat and intact OD/OS Anterior Chamber: deep and quiet OD/OS Crystalline lens: clear capsule, cortex, and nucleus OD/OS Digital intraocular pressure: OD/OS: soft and equal Time: 10:00AM Dilated with 0.5% Trompicamide Dilated Fundus Exam attempted but poor clinical views due to poor cooperation and constant movement from patient Ultrasound studies: B-scan ultrasonography: Retina is flat and intact OD/OS. Physical Child preferred leaning and turning head toward left side. Trial Frame (TF): OD: +1.00 sph 4 Prism Diopters Base Right OS: +1.00 sph 4 Prism Diopters Base Right Child appeared to have more straight head posture. However, it is unclear whether the patient was responding to TF or simply changed her posture consistent with her erratic movement. Others Visually Evoked Potential (VEP) Results: pending III. Differential diagnosis Primary/leading Little to no visual function vs. unable to elicit visual response. Schedule next available visually evoked potential to determine visual potential. Others Functional vision intact, suggested by VEP. IV. Diagnosis and discussion It has been suggest that because of the poor attention and lack of interest in behavioral tests, visually evoked potentials provide the most useful test of visual acuity in Rett Syndrome1. Despite some reports of successful visual acuity measurement by forced preferential looking methods, those methods were not able to be used in this case. In fact, no fix and follow response was consistently elicited. The severe motor decline of the patient who elicited incessant large head and limb movements throughout the exam must be taken into consideration, as the child may not have been able to motorically respond to the clinical testing. However, since the literature supports functional vision in the majority of Rett Syndrome, a visually evoked potential (VEP) is indicated, preferably to include grating potentials to estimate the potential visual acuity. It is important to note that a robust VEP response does not rule out cortical visual impairment2. If the VEP proves to have promising visual function results, spectacles should be trialed for improved behavioral results as reported by the parents and educational specialists. In this case, the optometrist should consider prescribing based right prism because of the child left visual field preference and left-leaning posture in order to possibly improve posture and front-facing gaze. The hyperopia could be corrected for better visual clarity in this case. Optometric evaluation of patients with Rett Syndrome, other developmental delays, and those with severe motor and/or verbal deficits must consider electrophysiological testing in cases where traditional clinical testing. Review of the literature confirmed the need to establish visual functional potential in this patient. Furthermore, the use of spectacles to correct refractive error and the use of prisms to correct posture or field preference must be considered for optimal visual function of patients with developmental disorders. Elaborate on the condition Rett syndrome is a neurodevelopmental disorder that affects females nearly exclusively in a ration of 1:10,000 to 1:22,000 live female births3. The syndrome is characterized by normal development until around 6 months of age followed by a slowing of developmental progress. Skills such as feeding, walking, and talking may be achieved which reach their peak around age 12 months. Shortly after, a period of regression in which speech and fine motor control are lost. Eventually, those affected lose nearly all function off their hands and become profoundly physically and mentally disabled. At this point, the condition stabilizes. The most common genetic mutation implicated in classic RS is a mutation of the methyl CpG binding protein 2, or MECP2 gene on the X chromosome4. The MeCP2 protein is responsible for gene expression during early development leading to the improper refinement of cortical circuits5. Interestingly, the MECP2 expression is very limited in the afferent visual pathway in normals and Rett Syndrome6. This corresponds to clinical findings of usually intact visual function in Rett Syndrome patients. Other mutations on the X chromosome in atypical RS are CDKL5 and WDR45. A mutation in FOXG1 on chromosome 14 has been identified in a congenital variant of RS. Recently, specific mutations in RS have been linked to specific functional outcomes in RS, such as hand use and ambulation7. Genetic testing for these mutations is now available, however diagnosis is based on the clinical phenotype. Rett Syndrome has a distinct profile of visual function, refractive error, and binocular status. Cortical visual impairment (CVI) has also been reported in those with Rett Syndrome8. CVI is defined as all visual dysfunctions caused by damage to, or malfunctioning of, the retrochiasmic pathways in the absence of any major ocular disease9. Despite demonstrating varying degrees of CVI, visual function is one of the few faculties that remain intact in RS. Visual acuity measured with forced preferential looking and visually evoked potential suggest that nearly all with Rett Syndrome maintain functional vision. Additionally, fix and follow function is retained 86-94% in RS10. Interestingly, a high incidence of nystagmus and strabismus seems to spare Rett Syndrome, unlike the majority of other neurodevelopmental disorders. However, there does seem to be a higher incidence of significant refractive error in Rett Syndrome compared to the normal population1,11. A distinctive feature and supporting diagnostic criteria of variant Rett Syndrome is intense fixed gaze and using eye-pointing, the latter of which has been reported as a method of communication 1,12,13,14,15. Prolonged gaze or staring has been linked to lower cognitive function in contrast to those who have a more active gaze11. Most cognitive testing relies on a motor or verbal response. Because visual function remains while motor and verbal abilities deteriorate, eye movement tracking technologies are now being used to test cognitive function instead of traditional methods16. Expound on unique features 1. Strabismus is unusual in Rett Syndrome: in one clinical study, only 1 in 11 patients with Rett Syndrome had strabismus and it was exotropic in nature1; in this case, per the report history, the child had esotropic strabismus and corrective eye muscle surgery. 2. Fixed gaze and eye-pointing have been reported as distinct features of the syndrome12,13,14,15 However, this patient did not exhibit those features. 3. There are conflicting reports of using forced preferential looking visual acuity methods successfully in Rett Syndrome Patients1,11; forced preferential looking was not able to be used in this case. 4. Flash and grating VEPs demonstrate potential for usable vision in RS1,17,18. Results pending from VEP and there is a possibility of an abnormal VEP compared to those of others with RS. 5. Fix and Follow skills are retained in 86%-94% of those with RS10 . This patient did not retain Fix and follow skills V. Treatment, management Electrodiagnostic testing is essential to the management of this patient’s visual function. If the VEP results indicate potential for functional vision, spectacle should be trialed for possible behavior improvements. If the VEP results indicate poor potential for functional vision, the parents and educational specialists need to be advised to focus on using other senses, such as auditory and touch, for learning and rehabilitation. Because patients with limited communication and cognitive ability cannot communicate when something is wrong or changes with their eyes or vision, these patients need to be examined regularly by an optometrist to monitor visual function and ocular health. VI. Conclusion This case does not fit the visual function profile of Rett Syndrome, but highlights important considerations in the management of patients with limited communication and motor abilities. 1. Saunders KJ, McCulloch DL, Kerr AM. Visual Function in Rett Syndrome. Dev Med Child Neurol 1995;37(6):496-505. 2. Wygnanski-Jaffe T, Panton C, Buncic J, et al. Paradoxical robust visual evoked potentials in young patient with cortical blindness. Doc Ophthalmol 2009;119(2):101-7. 3. Kozinetz C, Skender M, MacNoughton N, et al. Epidemiology of Rett Syndrome: A Population-Based Registry. Pediatrics 1993;91(2):445-450. 4. Hoffbuhr K, Devaney J, LaFleur B, et al. MeCP2 mutations in children with and without the phenotype of Rett syndrome. Neurology 2001;56(11):1486-95. 5. Durand S, Patrizi A, Quast K, et al. NMDA receptor regulation prevents regression of visual cortical function in the absence of MeCP2. Neuron 2012;76(6):1078-90. 6. Jain D, Singh K, Chirumamila S, et al. Ocular MECP2 protein expression in patients with and without Rett syndrome. Pediatr Neurol 2010;43(1):35-40. 7. Pidcock F, Saloria C, Bibat G, et al. Functional outcomes in Rett syndrome. Brain Dev 2015 [in press]. 8. Bosch D, Boonstra F, Willemsen M, et al. Low vision due to cerebral visual impairment: differentiating between acquired and genetic causes. BMC Ophthalmol 2014;14:59. 9. Fazzi E, Signorini S, Bova S, et al. Spectrum of Visual Disorders in Children with Cerebral Visual Impairment. J Child Neurol 2007;22(3):294-301. 10. Neul J, Lane J, Lee H, et al. Developmental delay in Rett syndrome: data from the natural history study. J Neurodev Disord 2014;6(1):20. 11. Tetzchner S, Jacobesn K, Smith L, et al. Vision, Cognition, and Developmental Characterstics of Girls and Women with Rett Syndrome. Dev Med Child Neurol 1996;38(3):212-225. 12. Olsson B and Rett A. Autism and Rett syndrome: behavioural investigations and differential diagnosis. Dev Med Child Neurol 1987;29:429-41. 13. Olsson B and Rett A. A review of Rett syndrome with a theory of autism. Brain Dev 1990;12:11-5. 14. Hagberg B and Skjeldal OH. Rett variant: a suggested model for inclusion criteria. Pediatr Neurol 1994;11:5-11. 15. Percy A, Neul J, Glaze D, et al. Rett syndrome diagnostic criteria: lessons from the Natural History Study. Ann Neurol 2010;68(6):951-5. 16. Rose S, Djukic A, Jankowski J, et al. Rett syndrome: an eye-tracking study of attention and recognition memory. Dev Med Child Neurol 2013;55(4):364-71. 17. Kálmáchey R. Evoked potential in the Rett Syndrome. Brain Dev 1990;12(1);736. 18. Bader G, Witt-Engerstrorn I, Hagberg B, et al. Neurophysiological Findings in the Rett Syndrome, II: Visual and Auditory Brainstem, Middle and Late Evoked Responses. Brain Dev 1988;11:110-4.