Flashcards
Corneal Evaluation: Basic, Lab, Topography
Flashcards do conjunto (40)
- 1Corneal Metabolism primarily relies on what two factors and how are they provided?Glucose from the aqueous through leaky endothelium
Oxygen from the atm
Limbal Capillaries also help provide both O2 and Glucose - 270-80 large nerves from branches of the long and short ______ nerves enter at:Long and short ciliary nerves enter at the peripheral stroma to innervate the cornea
- 3What are the 3 nerve networks and which causes severe pain in superficial abrasions1. Midstroma
2. Bowmans
3. Epithelium - causes the pain - 4What is the neurotrophic effect of corneal sensory nervesthey influence corneal metabolism and aid in tissue metabolism
- 5Which illumination technique occurs when the scope and illumination system are set at equal angles of incidence and reflection to evaluate the corneal *endothelium and anterior and posterior lenseSpecular Reflection
- 6Indirect Illumination is useful in evaluating:refractile, non-opaque (translucent) corneal lesions such as EMBD and microcysts
- 7Retroillumination of the ______ will have lesions appear darkened or black due to absorption of the reflected lightiris
- 8Retroillumination of the _____ shows lesions as dark or irregular areas on the corneafundus
- 9Sclerotic Scatter Illumination is most commonly used to:evaluate transparency of the cornea especially in central corneal clouding or CCC (will appear as gray areas in the cornea)
- 10CCC is observed using what illumination how?Sclerotic Scatter looking OUTSIDE the SL - assess cornea transparency
- 11What device helps determine the CL overwear and HSV by measuring corneal sensitivity and sensitivity to temperature.Esthesiometry
- 12Device used to measure TACTILE sensitivity of the eye by using controlled pulses of air as stimulation AKA cotton wisp testAesthesiometer
- 13Colbalt Blue illumination WITHOUT flurescein will cause corneal IRON LINES to appear how?black, and in a linear, arcuate, or circular pattern
- 14If one wanted to examine Fleisher's ring in keratonus what type of illumination should be used?Colbalt blue without flurescein
- 15What must be present in the TF for rose bengal to to penetrate ocular surface?break in TF
- 16Which two vital dyes are evaluated using white light?RB and LG
- 17Where LG stains dead cells and conjunctiva RB stains dead cells and mucous IN ADDIITON TO:Healthy cells as well (LG is dead and conj cells only)
- 18LG is useful for staining what disease and what ocular structureHSV and Bulbar Conjunctiva
- 19Corneal topography are able to determine refractive power for approx. how many mm of the central cornea10 mm
- 20Indications for corneal topography:Disorted mires with keratometry and suspected corneal disease
- 21Topography is most useful for evaluating what 4 ocular factors?1. CL fitting
2. Corneal Reshaping
3. Corneal Disease
4. Pre/post op evaluation - 22Name the most common map – displays power/curvature in diopters/mm relative to the keratoscope axis Best for describing general corneal shape and detecting changes over time (ex. Ortho-K)Axial power/curvature map
- 23Which map is most sensitive for PERIPHERY and is useful for analysis of keratoconus or transition areas (limbus) in corneal reshaping therapy or refractive surgeryTangential
- 24-Measurement of central corneal thickness -Average cornea 535-555 microns -Cornea thickness can impact Goldmann measurements -Commonly used in glaucoma diagnosis, refractive surgical evaluations, and monitoring corneal edema -Used to set target IOP for glaucoma patients Remember: thin corneal thickness --> higher risk factor for glaucoma (especially with elevated IOPs)Pachymetry
- 25-9,000 points in 1.5 seconds -Analyzes elevation and curvature measurements on both anterior and posterior surfaces of the cornea -Capable of detecting and analyzing posterior corneal abnormalities where corneal anomalies first appear -*Gives endothelial cell count -Measures pachymetry as well Not known to be one of the better topographers. All-in-one machine but not as accurate as each separate scanORBSCAN
- 26Non-invasive technique used to assess the corneal ENDOTHELIUM. Using computer-assisted morphometry, modern specular microscopes analyze the size, shape and population (density) of the endothelial cells. Must have clear cornea Used to evaluate DONOR corneas. A lot of donor corneas are now being harvested just for Descemet’s and endothelium (for a procedure called DSEK).Specular Microscopy
- 27Commonly used in research Good for viewing endothelium in edematous, cloudy corneas May be used to look in vivo at ‘live’ corneas, at a cellular level without causing harm to corneaConfocal
- 28“Ultrasound biomicroscopy” – B-scan with a lot more detail Relatively new technology, not used frequently in common practice Uses a high frequency probe (50 Hz, compared with 10 Hz commonly used in B-scan) Can be used in glaucoma, uveitis, trauma, opaque media, tumors, scleritis…High Resolution Ultrasound
- 29If viewed from the FRONT, the cornea appears _______. Horizontal Diameter = 12mm Anterior Vertical Diameter = 11mm If viewed from BEHIND, the cornea appears ________.Front= Oval
Back= Circular - 30Corneal OCT is indicated in:1. Keratoconus – can detect early, focal thinning. Will show greater curvature on anterior and posterior surfaces.
2. LASIK – can give precise thickness measurements across the cornea for enhancements or initial surgeries.
3. Planning PTK (PhotoTherapeutic Keratectomy) which smooths the irregular corneal surface –
4. Detecting corneal dystrophy –
5. Tear meniscus measurement in DES - 31How does corneal OCT help glaucoma specialist?Provides near-histological details of angle structures, helping glaucoma specialists.
- 32*** AKA OCULIS: uses a camera parallel to the slit beam to create an optic section and then uses a computer interface and calculates 3-D virtual images from the ANTERIOR segment.Scheimpflug Analysis
- 33Scheimpflug Analysis images ____ points and maures what 2 features of the cornea?25, 000 points to assess corneal THICKNESS and CURVATURE
- 34In addition to corneal THICKNESS and CURVATURE Scheimpflug Analysis also assesses what features of the ACA? (also does pachymetryVolume and Height of the ACA
- 35Which analysis provides an anterior and posterior limbus to limbus topographyScheimpflug Analysis
- 36Which instrument provides the best image quality of the ACA?OCT (NOT Scheimpflug analysis**)
- 37Pachymetry measurement of CCT is useful in:1. Glaucoma dx
2. Refractive surgical evaluation
3. Corneal edema monitoring - 38Which instrument counts endothelial cellsORBSCAN
- 39High Resolution Ultrasound uses a probe with a frequency of __ Hz and can be used in:50 Hz --> glaucoma, uveitis, trauma, opaque media, tumors, scleritis
- 40** What corneal degeneration REQUIRES corneal topography for dx?Pellucid Marginal Degeneration