Biomicroscopy

1. Biomicroscopy Dr. Laura A. Falco X 1452 lfalco@nova.edu

2. Introduction to Slit Lamp Biomicroscopy • Purpose: • Routine eye examination and/or • Ocular Trauma • Irritation • Infection • Inflammation

3. Biomicroscopy • Biomicroscopes have two integral systems: • 1. Viewing System (stereoscopic compound microscope) • 2. Illumination System(light source projected by an optical system)

4. Biomicroscopy • It is recommended to develop a routine that will be performed identically on every patient • Types of Commonly Used Illumination Techniques: • Diffuse Illumination: wide beam directed obliquely used for general scanning of the anterior segment • Direct Focal : focusing the beam and the microscope in the same specific area, usually requiring increased magnification

5. Illuminations • Parallelepiped: type of direct focal illumination, maximum height, approximately a 3mm width ( illuminates a 3-dimensional tissue area) • Optic Section: also a type of direct focal illumination using maximum height and “knife edge thin” <1mm width ( illuminates a 2-dimensional area like viewing a histological section) • Both of these illumination techniques will aide in viewing the cornea and crystalline lens

6. Illumination Systems • Direct • Sclerotic Scatter • Retro- Illumination • Specular reflection • Indirect (Proximal) • Diffuse (open aperture fully) • Tangential

7. Technique • Step by step guide to proper slit lamp biomicroscopy is available in your lab manual • Text: Atlas of Primary Eyecare Procedures, Fingeret, Casser, Woodcome, pp 20-25 • Practice, Practice Practice • Sequential observation is efficient! • Develop a routine that is repeated on each patient so that nothing is overlooked

8. Technique • Ideally you should have a dim to dark room while performing slit lamp examinations • The darker the room, the greater the contrast. • Direct Illumination: light source and binocular microscope are in co-incident position = “In click”

9. Biomicroscopy • Depending on structure to be examined, various angles between the light and the oculars are usually established and a variety of slit widths produced. • Direct Illumination: Optic Section used most often to see structures such as the lens and cornea in layer by layer. • An anterior to posterior approach is recommended

10. In a Nutshell: • Scanning across the ocular surface while looking for opacities/ abnormalities. Once the more anterior surfaces such as the conjunctiva, sclera, and cornea are examined, you can move more posteriorly towards the iris. It is possible to see the lens of the eye, however we prefer to fully examine the lenticular structure post dilation.

11. Biomicroscopy • After patient is positioned correctly in slit lamp biomicroscope the examination sequence is typically the following: • Please note that this is a brief introduction, your lab manual and your anatomy class will go into procedure and anatomy in much more detail

12. What am I looking at? • The Anterior Segment is the Front of the eye! • This will be a brief introduction to anterior segment anatomy

13. Normal Eye

14. Brief Overview of Structures

15. Method • Typical order of examining structures • Lids/lashes: broad beam diffuse illumination. Look for integrity, symmetry, growth pattern, loss of lashes, flakes or cones/caps at the base . Observe the meibomian glands. Lid and punctal apposition as well as completeness of blink is observed.

16. Examining Lids and Lashes • First while eye is closed, then open

17. Lids and Lashes

18. Abnormal Eye

19. Another Abnormal Eye

20. Lids and Lashes • Note the lid margin. Pay attention if it is flat and smooth, or bumpy and indurated. Watch for blood vessel growth, and adherence of the lid to the globe. Any signs of inflammation and infection should be noted. If the lids/lashes are normal they are recorded as clean and clear.

21. Eyelid Geography • The different conjuctivae:

22. Look Closely at the Eyelids • After examining the eyelids, the palpebral conjunctiva is examined

23. Cont’d… • The conjunctiva should appear uniform. • Palpebral conjunctiva: Round bumps = papillae = allergic disease. Long bumps = follicles = viral. Want a smooth, lustrous surface • Bulbar conjunctiva: should see blood vessels, but not grossly engorged vessels. Episcleral vessels may have a more purplish hue and are deeper than the bulbar conjunctival blood vessels.

24. Lids and Lashes • After lash and lid observation the tear film conjunctiva and cornea can be assessed using Paralellopiped illumination. • Maximum Beam Height • @ 2-3mm Beam Width • Medium Illumination

25. Bulbar Conjunctiva • Now you can move onto examining the bulbar conjunctiva

26. Examine the “Whites” of their Eyes • The Sclera is the “white part” of the eye • This is the tough outer wall of the eye that protects the delicate inner structures • Under the Sclera you have the choroid • This is made up of blood vessels that provide nourishment to the eye

27. Choroid • Choroidal Vasculature

28. Cornea • The cornea is the clear part of the eye through which the iris (colored part) can be seen • It is the main source of refraction • It is made up of 5 layers of strong, transparent tissue • Anterior Epithelium, Bowman’s membrane, Stroma (thickest layer), Descemet’s membrane and finally the Endothelial cell layer (most posterior)

29. Cornea • Cornea is about .5mm thick • Avascular (normally) • The Anterior Epithelium is the anterior surface that is a few layers thick and are renewed at a weekly rate. • Bowman’s layer: densely packed collagen fibrils and serves as a significant protection to mechanical trauma

30. Cornea • Stroma: thickest layer, seen as a dark band with optic section Any non uniformity of the stroma should be taken as evidence of corneal thinning and certain disorders must be ruled out. • Descemet’s Layer: posterior barrier. Very difficult to visualize • Endothelial Layer: last (most posterior layer). Can only be viewed with specular reflection and exhibits a hexagonal pattern.

31. Layers of the Cornea • Examining the cornea, we switch our magnification to 16x and scale down from diffuse light to a parallelpiped and/or optic section • Maximum height • Medium-High illumination 1-3mm beam width

32. Corneal Layers

33. Iris • This is the colored part of the eye; it can constrict and dilate to control the size of the pupil. (Future Fingerprint)

34. Iris • Composed of two layers, the stroma anteriorly and the epithelium posteriorly. • Density of pigment in the stromal melanocytes determines eye color. • The stroma also contains crypts • Collarette (minor circle of the iris) • Pupillary Frill (at pupil border)

35. Iris • Blood vessels may be visible in patient’s with light colored irides • Heterochromia: • Congenital • Acquired • Secondary to : inflammation/trauma

36. Iris • May have freckles and nevi: • Freckles: within iris stromal substance • Nevi: on iris stromal surface Iris can be examined by using broad beam diffuse light, paralellopiped or retro-illumination.

37. Iris • Of course we can’t forget the other type of Iris………

38. The Infamous Limbus • This is the area where the cornea becomes one with the bulbar conjunctiva. Remember it occurs 360° around the entire cornea.

39. The Lens • This is responsible for 1/3rd of the refracting power of the eye. Located posterior to the Iris, it allows the eye to alter focus by changing shape. The changing focus is called: accommodation.Due to a variety of factors as we age it becomes more difficult for people to accommodate.

40. The Lens

41. The Lens • This optic-section reveals cornea(first white line), anterior chamber(black space) and lens posteriorly

42. Lens Zonules and the Ciliary Body • Zonules: “threads” that attach the lens to the Ciliary Muscle • Ciliary Body: contains the ciliary muscle and a gland that produces a fluid called aqueous humor.

43. The Aqueous Humor • The Aqueous humor is fluid that is produced by the Ciliary Body. It circulates into the front part of the eye. This is responsible for maintaining eye pressure (Intra-ocular pressure, aka IOP)

44. Path of the Aqueous

45. Anterior Chamber • Fluid that is produced by the ciliary body eventually circulates anterior to the lens, through the pupil and into the trabecular meshwork. While it is circulating in the front part of the eye, it occupies the anterior chamber. This optically empty space posterior to the cornea and anterior to the iris.

46. Trabecular Meshwork • Structure that resembles “swiss cheese” with may holes that the Aqueous humor can percolate through before being drained from the eyeball. (globe) This is also referred to as the ANGLE of the eye. When the angle is open, fluid goes through, when it is closed, fluid is unable to flow through and consequently the IOP of the eye will elevate.

47. The Angle • Fluid drains into the meshwork. Note the angular appearance.

48. The Vitreous • This clear gel fills the core of the eye. It helps the eye keep a round shape. Over time it changes and patients will report seeing “floating spots” in their vision. This is most likely due to the changes within the vitreous.

49. Vitreous • This is a picture of the vitreous that is detaching superiorly.

50. Recording • For Legal reasons it is important to document what you observe. This is your only proof that you examined a patient. • Always describe anything that appears abnormal/different • Measure any growths annually • WNL: we never looked • Lids/Lashes: describe any abnormality or record as clean and clear