Corneal Evaluation

Slit lamps equipped with photography instrumentation are able to image the front of the eye, including the cornea. Dynamic viewing capabilities allow for multiple methods of analysis of corneal health.

Zeiss SL800

Slit Lamp Biomicroscopy

The health of the corneal epithelium can be examined more closely with vital dyes. Staining with sodium fluorescein and lissamine green are used for this assessment.

Much like the Zeiss slit lamp, the Takagi SM-70N is used to image the anterior eye including the cornea and is also equipped with a Wratten filter and cobalt blue lighting.

Takagi SM-70N

Slit Lamp Biomicroscopy

This instrument uses reflective rings to capture an infrared image of the anterior cornea, through which corneal diameter (HVID) can be measured. The scan captured provides quantitative data about the anterior cornea (Placido imaging) including:

  • Keratometry values

  • Corneal elevation

  • Refractive power

  • Tangential and axial maps

  • Shape descriptors such as e, p, Q and IS values

Two maps captured on the Medmont E300 can be compared using a difference map, which can be useful in showing change over time.

Medmont E300

Corneal Topography

Corneal tomography is captured using Schleimpflug imaging to provide data about the anterior and posterior cornea. This data includes:

  • Keratometry readings

  • Corneal thickness

  • Anterior and posterior corneal elevation

  • Corneoscleral height

  • Refractive power

  • Tangential and axial maps

  • Shape descriptors such as e, p, Q and IS values

  • Schleimpflug images (infrared photos and B-scans of the anterior eye)

  • Corneal diameter (HVID)

  • Corneal densitometry

Oculus Pentacam AXL Wave

Corneal Tomography, Ocular Biometry & Wavefront Aberrometry

The Oculus Pentacam also measures wavefront aberrometry and can distinguish between corneal and total aberrations.

Much like the Oculus Pentacam, the Zeiss iProfiler Plus is used to measure the optical aberrations of the eye and can separate total aberrations from corneal.

Zeiss iProfiler Plus

Wavefront Aberrometry

Using sodium fluorescein reflection-based imaging, this instrument provides corneal and scleral readings including:

  • Keratometry values

  • Corneal elevation

  • Refractive power

  • Tangential and axial maps

  • Shape descriptors such as e, p, Q and IS values

  • Corneoscleral sagittal height

Eaglet Eye ESP

Corneoscleral Profilometry

Specular microscopy is a non-invasive means of collecting information on the cornea and specifically the corneal endothelium at the central, midperipheral and peripheral cornea. The Tomey EM-4000 analyses up to 300 cells of the corneal endothelium over a 0.25x0.54mm capture area, measuring:

  • Cell density (CD)

  • Average cell area (AVG)

  • Coefficient of variation of cell area (CV)

  • Percentage of hexagonal cells (6A)

Tomey EM-4000

Specular Microscopy

Anterior OCT captures information including corneal thickness (central and peripheral) and corneal transparency.

Heidelberg Spectralis

Anterior OCT (Optical Coherence Tomography)

Much like the Heidelberg Spectralis, this OCT captures corneal thickness and transparency data. It can also perform epithelial thickness mapping on the cornea.

Zeiss Cirrus 6000 Angioplex

Anterior OCT (Optical Coherence Tomography)

The Zeiss IOLMaster 500 provides keratometry readings based on an average of 6 separate readings.

Zeiss IOLMaster 500

Ocular Biometry