photos

Alignment of

the mires on a Bausch

and Lomb keratometer.

(a) The view when the

mires are off the principal

meridians. (b) The view

when the mires are on the

principal meridians.

(c) The view when the

plus and minus signs are

overlapping to measure

the ‘horizontal’ and

‘vertical’ radii of

curvatu

The mire

images as seen on the

Javal Schiotz keratometer.

(a) Aligned mire images

along the horizontal.

(b) Mires from (a) touching

with no overlap. (c) Non-

aligned mire images. (d)

Mire images from (c)

brought into alignment

along an oblique

meridian. (e) Mires from

(d) touching with no

overlap.

focimeter target

Full distance power

Fitting cross

Major reference point

Distortion area

Full near add power

Limbar Zone

Peripheral Zone

Mid-peripheral Zone

+ ContralZone

Corneal Center

Figure 3. Helmholtz keratometer.

Figure 4. The Javal keratometer.

Figure 5. Autorefractometer.

Figure 5. Placido disk keratoscope.

Corneal topographers (Pentacam).

Figure 8. Scheimpflug camera principle.

Color coded topographic maps.

Anterior Sagittal maps.

Symmetric bowtie.

Abnormal patterns of corneal topography.

Elevation maps.

Keratoconus

The kissing birds sign.

Pachymetry maps.

Abnormal patterns in pachymetry maps.

Integrated Indices.

BAD_D display-normal aspect

Abnormal patterns of BAD_D display.

Ambrosio relational thickness.

The ABCD classification of keratoconus.

keratometric formula

Cornea as a spherical mirror

aperture in thekeratometer optical system

scheiner disk focusing mechanism

corneal astigmatism

keratometric astigmatism

jackson cross cylinder

schematic eye