Sensory - Vision Abnormalities

From Embryology
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Introduction

These notes introduce the abnormal development of the eye and vision associated structures.

Anophthalmia (absence of an eye) and microphthalmia (small eye within the orbit) have a combined birth prevalence of approximately 30 per 100,000 population.[1]

Genetic factors include developmental transcription factors required for inductive/developmental events in the structure of the eye and retina development.

Environmental factors include gestational-acquired infections, maternal vitamin A deficiency, smoking, X-ray exposure, solvent misuse and thalidomide exposure.



Vision Links: vision | lens | retina | placode | extraocular muscle | cornea | eyelid | lacrima gland | vision abnormalities | Student project 1 | Student project 2 | Category:Vision | sensory
Historic Embryology - Vision 
Historic Embryology: 1906 Eye Embryology | 1907 Development Atlas | 1912 Eye Development | 1912 Nasolacrimal Duct | 1917 Extraocular Muscle | 1918 Grays Anatomy | 1921 Eye Development | 1922 Optic Primordia | 1925 Eyeball and optic nerve | 1925 Iris | 1927 Oculomotor | 1928 Human Retina | 1928 Retina | 1928 Hyaloid Canal | Historic Disclaimer

Some Recent Findings

  • Functional and Molecular Characterization of Rod-like Cells from Retinal Stem Cells Derived from the Adult Ciliary Epithelium[2] "In vitro generation of photoreceptors from stem cells is of great interest for the development of regenerative medicine approaches for patients affected by retinal degeneration and for high throughput drug screens for these diseases. In this study, we show unprecedented high percentages of rod-fated cells from retinal stem cells of the adult ciliary epithelium. Molecular characterization of rod-like cells demonstrates that they lose ciliary epithelial characteristics but acquire photoreceptor features. Rod maturation was evaluated at two levels: gene expression and electrophysiological functionality. Here we present a strong correlation between phototransduction protein expression and functionality of the cells in vitro. We demonstrate that in vitro generated rod-like cells express cGMP-gated channels that are gated by endogenous cGMP. We also identified voltage-gated channels necessary for rod maturation and viability. This level of analysis for the first time provides evidence that adult retinal stem cells can generate highly homogeneous rod-fated cells."
  • Stem cell therapy for retinal disease[3] "Stem cells can now be directed to specific retinal cell fates with high yields and acceptable purity for clinical trials. New stem cell sources have been discovered including induced pluripotent stem cells that can be derived from adult tissues then differentiated into multiple retinal cell types. The initial results of clinical trials of subretinal transplantation of human embryonic stem cell-derived retinal pigment epithelium cells in patients with Stargardt's macular dystrophy and dry age-related macular degeneration showed preliminary safety and possible visual acuity benefits. A phase I trial of intravitreally injected autologous bone marrow-derived mononuclear cells for hereditary retinal dystrophy demonstrated no evidence of toxicity with possible visual acuity benefits but no structural or functional changes. Ongoing trials are examining the trophic effects of undifferentiated umbilical cells for the treatment of geographic atrophy in age-related macular degeneration."
  • Targeted 'next-generation' sequencing in anophthalmia and microphthalmia patients confirms SOX2, OTX2 and FOXE3 mutations[4]"Anophthalmia/microphthalmia (A/M) is caused by mutations in several different transcription factors, but mutations in each causative gene are relatively rare, emphasizing the need for a testing approach that screens multiple genes simultaneously. We used next-generation sequencing to screen 15 A/M patients for mutations in 9 pathogenic genes to evaluate this technology for screening in A/M."


Recent References | References

Neonatal Vision

Vision in the developing infant can be assessed by a number of tests for: central vision, stereoscopic (binocular) vision, refraction, color vision, contrast vision, scotopic/photopic (dark/light) vision (retina/rods), and tracking (following and saccades), (retina, oculomotor muscles).

Preterm infants have been shown to develop a number of vision related abnormalities including: visual impairment, oculomotor abnormalities, and refractive error.[5]

Newborn-normal-behaviour.jpg Newborn n 02.jpg
normal behaviour cranial nerves


Links: Movie - Newborn normal behaviour

Anophthalmia

Anophthalmia and microphthalmia

Anophthalmia is clinical description for the absence of an eye. Gene mutation of SOX2, a developmental transcription factor, has been associated with this condition.

Microphthalmia

Microphthalmia is clinical description for the presence of a small eye within the orbit and occurs in up to 11% of blind children.

Ferda Percin E, Ploder LA, Yu JJ, Arici K, Horsford DJ, Rutherford A, Bapat B, Cox DW, Duncan AM, Kalnins VI, Kocak-Altintas A, Sowden JC, Traboulsi E, Sarfarazi M, McInnes RR. Human microphthalmia associated with mutations in the retinal homeobox gene CHX10. Nat Genet. 2000 Aug;25(4):397-401.


Syndromic microphthalmia-9 can be caused by mutations in the Stimulated by Retinoic Acid 6 (STRA6) gene. OMIM - MCOPS9

Bardet-Biedl Syndrome

(BBS) is an abnormality with triallelic inheritance and is characterized by a range of multisystem abnormalities incliuding postnatal developmental blindness.

cone-rod dystrophy truncal obesity postaxial polydactyly cognitive impairment neural development male hypogonadotrophic hypogonadism female genitourinary malformations renal dysfunction (More? OMIM - Bardet-Biedl syndrome | GeneReviews - Bardet-Biedl syndrome)


Pax6 Mutation

Pax6 eye phenotypes.jpg

Phenotypes of wild-type (top) and PAX6 ortholog mutations (bottom) in human, mouse, zebrafish, and fly.[6]

Human mutations may result in aniridia (absence of iris), corneal opacity (aniridia-related keratopathy), cataract (lens clouding), glaucoma, and long-term retinal degeneration.

Congenital Rubella Syndrome

Congenital rubella syndrome (CRS) occurs as a result of a maternal rubella infection during the first trimester of pregnancy and is most commonly associated neural, cardiac and sensory abnormalities. Approximately 25% suffer from congenital cataracts and other eye abnormalities include pigmentary retinopathy and iris hypoplasia.


Links: Abnormal Development - Rubella Virus

World Statistics

Sweden

Rate of anophthalmia decreased from the early 1970s from 0.4 to 0.2 per 10,000 births. Non-eye malformations were more common at anophthalmia (63%) than at microphthalmia (30%) Maternal smoking in early pregnancy seemed to increase the risk for anophthalmia or microphthalmia in the absence of a coloboma.[7]

United Kingdom

1988-94 prevalence of anophthalmia and microphthalmia was 1.0 per 10,000 births.[8]


USA California

1989-1997 prevalence per 10,000 livebirths and stillbirths for anophthalmia was 0.18 and for bilateral microphthalmia was 0.22. Risk of anophthalmia was approximately twofold among multiple births compared to singletons. (More? Shaw GM, etal., 2005)

References

  1. <pubmed>18039390</pubmed>
  2. <pubmed22432014 </pubmed>
  3. <pubmed>22450217</pubmed>
  4. <pubmed>22204637</pubmed>
  5. <pubmed>12014889</pubmed>
  6. <pubmed>19956802</pubmed>| PLoS Biol.
  7. <pubmed>15971507</pubmed>
  8. <pubmed>10194985</pubmed>

Online Textbooks

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Cite this page: Hill, M.A. (2024, March 28) Embryology Sensory - Vision Abnormalities. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Sensory_-_Vision_Abnormalities

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G