Cornea and Anterior Chamber Exam Techniques - Biology Study Set

what is superficial punctate keratitis or punctate epithelial erosions?

- Small, tiny defects in the corneal EPITHELIUM, seen as pinpoint white opacities

- use fluorescein for staining

- multiple etiologies

what are keratic precipitates?

- deposites on the corneal endothelium composed of inflammatory cell (lymphocytes, plasma cells, macrophages)

what are keratic precipitate commonly in?

- often seen in uveitis

- inflammation of the uvea, accompanied with anterior chamber reaction

- observed with direct illumination

- better observed with indirect and retro

What are subepithelial Infiltrates (SEIs)?

- Accumulation of WBC in the cornea (avascular), an immune mediate response

- Generally observed in viral infections, contact lens hypersensitivity or severe blepharitis

what is the best way to see SEIs?

- indirect illumination

what is a corneal arcus?

- age related bilateral peripheral corneal degeneration associated with lipid deposits at level of Bowman's and Descemet's Membrane

- clear zone between arcus and limbus

where does corneal arcus starts?

- inf and sup cornea and eventually circumferential

what slit lamp technique is used for detection of corneal arcus?

- wide parallelpiped

What is Limbal girdle of Vogt?

- White cresent shaped opacities found at nasal and temporal limbus (*3 o'clock and 9 o'clock*) interpalpebral positions

- benign finding in the elderly, age related

what is used to detect for limbal girdle of Vogts?

- wide beam and or parallelpiped for detection

what is used to differentiate limbal girdle of Vogt from Corneal Arcus?

- Indirect

what is endothelial dystrophy / Fuch's Dystrophy?

- Corneal dystrophy involving abnormalities in Descemet's membrane

what are clinical signs of endothelial dystrophy / Fuch's dystrophy?

gutatta: (pigmented or nonpigmented)

- Observed as 'droplets' or a 'beaten metal appearance

- Direct, retroillumination, specular reflection, optic section

stromal edema:

- Observed as corneal haze

- Sclerotic scatter, direct, optic section

what illumination technique would be used for endothelial/Fuch's dystrophy?

- illumination techniques that study the endothelium

what are the types of corneal opacities/scars?

- nebular

- macular

- leukoma

what is a nebular scar and how does it affect vision?

- very mild stromal opacification that is viewed with slit lamp

- typically no effect on vision

what is a macular scar and how does it affect vision?

- moderates stromal scar that can be seen with slip lamp

- VA can be affected

what is a leukoma scar and how does it affect vision?

- more than 1/2 opacification of stroma that can be seen w/o slit lamp

- VA significantly reduced

what are the signs of keratoconus?

- munsun sign: external observation

- fleisher ring: can be seen with wide PP

- acute hydrops: can be seen with optic section

- vogts Striae: multiple techniques

- inferior stromal thinning: can be seen with optic section

how would you document normal cornea?

- clear epi, stroma, endo

how would you document an abnormal cornea?

describe location of lesion:

- location, use clock hour

- size: measure by changing height of beam

- quantity: isolated, multiple

- other characteristics: (color, thickness, neovasculariztion, dendrite, ulcer, whorl like, map like, etc)

- grading scale when applicable

what is Van Herick used for?

- To reliably estimate the depth of the anterior chamber angle prior to pupil dilation

*Compares anterior chamber depth (seen as a shadow) to corneal thickness (created by optic section) * optic section MUST BE IN FOCUS

what is the set up for Van Herick?

- FIRST full Optic section at the corneal side of the limbus

- check nasal and temporal

what is VH grade 4?

- AC depth is 1 or greater than 1 of the corneal thickness

- wide open

- 35-45 degrees

what is VH grade 3?

- AC depth is 1/2 to 1/4 of the corneal thickness

- open, angle unlikely to close

- 20-34 degrees

what is VH grade 2?

- AC depth is 1/4 of corneal thickness

- narrow, capable of closing

- 11-19 degrees

what is VH grade 1?

- AC depth is < 1/4 of corneal thickness

- extremely narrow, will probably close

- 10 or less degrees

what Van Herick grades are considered safe to dilate?

- 4 and 3

What Van Herick grades is gonioscopy strongly recommended?

- less than 2

- determine if patient is at risk for angle closure with dilation

how will Van Herick grading be affected if optic section is moved too centrally?

- overestimation

how will Van Herick grading be affected if optic section is moved towards bulbar conj?

- underestimated

- will be difficult to see

What is conical beam used for?

- evaluation of the presence of material like cells and/or flare in the aqueous humor within the AC

- only occurs when materials like cell or flare is present in AC

what optical property does conical beam utilize?

- Tyndall Effect

what is the set up for conical beam?

- Narrow parallelepiped 1mm wide x 3mm tall (Used to assess)

- **Conic section : 1mm wide x 1 mm tall (Used to grade/quantify)

- illumination angle: 30-45

- intensity: Max

- High mag: 25x

- examiner needs to dark adapt for 30 seconds

what does swinging conical beam left/right help do?

- increase surface viewing area

- help see cells and flare easier

- do not go up/down, convection current will being cells into light

what are cells and flare indicative of?

- iritis/uveitis

what is flare?

- Light striking floating protein in the AC is reflected or scattered

what are cells?

- Light striking cells is reflected or scattered

- WBCs = white dots = inflammation

what is Standardization of Uveitis Nomenclature grading of cells and what is it based on?

- grade 0: no cells

- 0.5+ (trace): 1-5

- 1+: 6-15 cells

- 2+: 16-25 cells

- 3+: 26-50 cells

-4+: >50 cells

*** based on 1x1 conical beam

what is Standardization of Uveitis Nomenclature grading of flares and what is it based on?

- grade 0: no flare

- 0.5+ (trace):

- 1+: faint

- 2+: moderate (iris and lens detail clear)

- 3+: marked (iris and lens detail hazy)

-4+: intense (fibrin/plasma aqueous)

*** based on 1x1 conical beam

what is hypopyon?

- Accumulation of white blood cells in the anterior chamber

what is hyphema?

- blood in the anterior chamber of the eye

what can lead to hyphema?

- Blunt trauma cause traction along the iris root

- Leading to a tear between the longitudinal and circular muscles of the CB

- With enough force, ciliary arteries can be broking leading to hyphema

how would you document AC?

1. record AC depth using Van Herick

2. Status of AC

note for cells/flare

if normal document CLEAR or QUIET