embryology of lids and adnexa.pptx embryology

Ophthalmology
Medicine
Medical science

1. EMBRYOLOGY OF LIDS AND ADNEXA Dr Bishop Mukhiya 1 st year resident TIO

2. EMBRYOLOGY OF LIDS AND ADNEXA Eyelids Lid appendages Eyelashes Glands of Zeiss and Moll Meibomian glands Lacrimal glands Lacrimal sac and nasolacrimal duct Orbit

3. INTRODUCTION Is a mobile flexible structure that covers the globe anteriorly Upper and lower eyelids Upper eyelids extends into eyebrows and lower eyelids into cheeks Assists in reforming, distribution and drainage of tear Act as shutters protecting eyes from injuries, foreign bodyand excessive light Provides information regarding the state of wakefulness and attention and facial expression

4. OVERVIEW OF EMBRYOGENESIS

5. Contd …

6. Eyelids and adnexa are embryologically derived from…. SURFACE ECTODERM NEURAL CREST CELL MESODERM

7. D E V E L O P M E N T O F E Y E L I D PHASES OF DEVELOPMENT 1.FORMATION 2.FUSION 3.DEVELOPMENT 4.SEPARATION 5 . M A T U R A T I ON O F E Y E L I D S T R UC T U R ES

8. DEVELOPMENT OF EYELID Begins at 4-5 weeks of gestation Develops as the fold of surface ectoderm above and below developing cornea Fuses at about 6 th -8 th week of IUL Remain fused till about 5 th month when they start to separate Separation is completed by 7 th month

9. FUSION OF LID FOLDS

10. Separation of lids Secrection of sebum by meibomian gland . Progressive keratinization of eyelid margin induced by epidermal growth factor Contaraction of lid retractors

11. Lid appendages and Pilosebaceous glands Takes place between 3 rd and 6 th month Eyelashes/ cilia: -Proliferation of the surface epithelial cells into the underlying mesenchyme while maintaining an intact basal lamina - it is followed by the differentiation of hair follicles Sebaceous gland of Zeis : -appears as lateral outgrowth from invaginated epithelial cells -production of lipids soon commences and it is secreted into hair shaft -thereafter the canal becomes keratinized Sebaceous Meibomian gland: -formed by the ingrowth of basal epithelial cells at the inner margin Sweat glands of Moll: -arise from the walls of the hair sac

12. Origin of lid structure Ectoderm Mesoderm Neural crest mesenchyme Lash follicles Striated muscle Melanocytes Meibomian glands Endothelium of blood vessel pericytes Eyelid glands Schwann cells Conjunctiva Tarsal plate, LPS aponeurosis , ligaments Lacrimal puncta and canaliculi

13. Congenital anomalies of lid 1.Anomalies of eyelid margin Ankyloblepharon Euryblepharon Epiblepharon Epicanthal fold Congenital Entropion Congenital Ectropian Congenital Distichiasis 2. Anomalies of lid fold development Cryptophthalmus Microblepharon Ablepharon Colobomas

14. Contd …. 3. Anomalies of fissure Blepharophimosis syndrome Congenital ptosis 4. Abnormalities of canthal tendon: Telecanthus Medial Canthal Dystopia 5. Vascular Eyelid Tumors: Capillary ( Infantile) hemangioma Port wine stain

15. ANKYLOBLEPHERON It is fusion between the upper and lower eyelid External- fusion occurs at lateral canthus , most common Internal- fusion occurs at inner canthus Usually autosomal dominant, may be sporadic May give rise to Pseudoexotropia or pseudoesotropia

16. Bilateral temporal Congenital Ankyloblepharon

17. ANKYLOBLEPHARON FILIFORME ADANTUM It is presence of isolated strands of extensile tissue passing between upper and lower lid margin Often results in shortening of vertical palpebral aperture Semantic Scholar- Source

18. EURYBLEPHARON It is symmetrical enlargement of horizontal palpebral fissure Other features : Downward and anterior displacement of lateral canthus , ectropion of lateral third of lower lid, tightness of the lids Usually isolated condition Also may be associated with ptosis , distichiasis , telecanthus , strabismus or abortive cryptophthalmos

19. EPICANTHAL FOLDS It is a semilunar fold of skin running downwards at the side of the nose with its concavity dirrected to the inner canthus.that may result from immature mid-facial bones or folds of skin and subcutaneous tissue Folds may extend from upper to lower lids towards the medial canthi pseudoesotropia

20. CONTD…. Four types: Epicanthus Superciliaris Epicanthus Tarsalis Epicanthus Palpebralis Epicanthus Inversus

21. EPIBLEPHARON It is extra horizontal fold of skin stretching across the anterior lid margin, causing cilia to assume a vertical position Common in Asians, mainly occurring in medial part of lower eyelid Cilia often do not touch cornea except in downgaze

22. CONGENITAL ENTROPION It is inward turning of lid margin towards the globe Often isolated , may ocassionally occurs secondary to microphthalmus , epiblepharon and anopthalmous Often confused with epiblepharon .

23. Congenital ectropion It is outward turning of the lid margin away from globe Often associated with Blepharophimosis syndrome, Downs syndrome or ichthyosis Due to vertical insufficiency of anterior lamella of eyelid Chronic epiphora and exposure keratitis

24. Congenital distichiasis There is extra row of eyelashes in place of orifice of mebomian glands It is due to improper differentiation of embryonic pilosebaceous unit into hair follicle . If symptomatic or keratopathy develops treatment is done as soon as possible

25. Cryptophthalmos It is the condition where globe and deeper ocular structures are covered by the sheet of skin that extend from brow to the cheek Autosomal recessive condition Can be U/L or B/L Typically ocurs in association with Fraser syndrome It is of : a. complete cryptophthalmos b. partial cryptophthalmos c. abortive cryptophthalmos

26. Complete type

27. Partial type

28. Abortive type

29. Microblepharon Small eyelids with shortening in vertical dimension Presentation vary from mild vertical shortening to almost complete colobomatous absent of lid.

30. Ablepharon Rare disorder characterized by complete failure of lid development

31. Colobomas It is partial of full thickness eyelid defect Due to: Defect in migration of neural crest cells Amniotic bands Failure of fusion of lid folds

32. Blepharophimosis-ptosis-epicanthus inversus syndrome( bpes ) Autosomal dominant, sporadic mutation can occur Occurs due to mutation in FOXL2 gene located on chromosome 3 Finding: Blepharophimosis Telecanthus Moderate to Severe bilateral ptosis Epicanthus inversion

33. Congenital ptosis It is characterized by a drooping or inability to raise the upper lid, frequently associated with impaired upward movement of the eye. Due to failure of peripheral differentiation of muscles developmental myopathy of levator . It is a reversible cause of peripheral vision loss- superior visual field usually

34. Congenital myogenic ptosis : Results from dysgenesis of levator muscle Characterized by decreased levator function, eyelid lag and sometimes lagophthalmos Severe form- upper eyelid crease absent or poorly formed

35. Congenital neurogenic ptosis : Caused by denervational defects during embryonic development Commonly associated with Congenital cranial nerve III palsy Congenital Horner Syndrome or Marcus Gunn Jaw winking syndrome

36. Telecanthus It is increased distance between the medial canthi Due to abnormally long medial canthal tendons Uncommon ; isolation or in association with BPES Can be confused with hypertelorism

37. Medial canthal dystopia Autosomal dominant Abnormal formation of medial canthal tendon – due to arrest at 2 months of development Features: Medial ankyloblepharon Telecanthus Lateralization of puncti Prominent root of nose

38. Capillary hemangioma It is Unilateral, red, raised lesion Lesion usually develops within few weeks or months after birth, increase in size over first year and involutes gradually over the next 3-7 years

39. Port Wine Stain Also called port wine nevus or nevus flammeus Congenital vascular malformation, manifest as flat red or pink cutaneous lesion May lighten during first year of life but then tend to become darker, thicker more nodular overtime

40. Lacrimal glands Begins to develop at about 45 days of gestation Solid cords of epithelial cells proliferates from the basal cells of conjunctiva located at the temporal region of upper fornix Surrounding neural crest mesenchymal cells condense around the tip of the cords and differentiate into lacrimal gland At 3 months ducts of the glands are formed by vacuolisation of the cords.

41. Lacrimal Drainage System By the end of 5 th week of gestation, the nasolacrimal groove forms as a furrow lying between the nasal and maxillary prominence. In the floor of this groove, Nasolacrimal duct(NLD) develops from the linear thickening of the ectoderm. The solid cord separtes from the ectoderm and sinks in the mesenchyme . The cord canalises forming lacrimal sac in its cranial end and NLD. The canaliculi are thought to form similarly from the invaginated ectoderm continuous with the distal cord. Caudally the duct extends intranasally , exiting within the inferior meatus .

42. ANOMALIES OF THE LACRIMAL APPARATUS

43. NASOLACRIMAL DUCT OBSTRUCTION Most common abnormality Seen in 20-30%of new borns At the lower end of the duct High risk of developing Dacryocystitis .

44. CONGENITAL DACRYOCELE Collection of mucus in the lacrimal sac caused by an imperforate Hasner valve

45. Development of Orbit Begins at 6 th week of gestation Derived form cranial neural crest cells which expand to form Frontonasal process Maxillary process

46. Bones differentiate during 3rd month and later undergo ossification Ossification by enchondral or membranous type Growth of orbit corresponds with growth of eyeball

47. Anophthalmos It is total absence of tissue of the eye Clinical anophthalmos : No clinical or radiographic evidence of any ocular remnant True anophthalmos : verified after careful histologic sectioning of the orbital tissues

48. Three types Primary anophthalmos : rare and usually bilateral, primary optic vesicle fails to grow out from cerebral vesicle Secondary anophthalmos : rare and lethal, due to gross abnormality in the anterior neural tube Consecutive anophthalmos : due to Secondary degeneration of the optic vesicle

49. Contd … Orbits and eyelids are small but well formed Conjunctival fornices decreased in size Eye cannot be felt in the orbit on palpation Extraocular muscle may be well developed

50. Microphthalmos Small eye, with axial length at least 2SD below the mean axial length for age Results from incomplete invagination of optic vesicle or closure of embryonic fissure

51. Congenital anomalies may be isolated or associated with other eyelid, facial or symmetric anomalies. Careful evaluation of patients with hereditary syndromes is helpful before proceeding with treatment Most congenital anomalies of the eyelids are rare and occur during the second month of gestation as a result of developmental arrest or failure of fusion 53

52. Reference Kanski’s Clinical Ophthalmology , Ninth Edition Fundamentals and Principles of Ophthalmology , AAO -BSCS 2022-2023 Oculofacial Plastic and Orbital Surgery, AAO- BCSC 2022-2023 Albert & Jakobiec’s Principles and Practice of Ophthalmology, 3 rd edition Wolff’s anatomy 54