4-11
■
4.2 Verification when measuring axial length
OA-2000 measures the distance from the lacrimal
fluid on the corneal surface to the retinal pigment
epithelium (RPE) as the axial length.
Normally, the waveform height and width of the
internal limiting membrane and choroid are
smaller than those of the retinal pigment
epithelium. (Fig. 1)
Reflection from the internal limiting membrane
(ILM) may be received depending on the
condition of the retina. (Fig. 2)
If the waveform of the internal limiting membrane is
larger than that of the retinal pigment epithelium, the
resultant axial length may be shortened by 0.15 –
0.35 mm.
If values of the axial length are varied or individual
waveforms seem to show that the retinal pigment
epithelium was not correctly captured, thoroughly
evaluate the measurement data, referring to the
following points.
- Take measurement again.
- Compare the data with the measurement taken
in ultrasound A mode.
- Check for the presence of ocular fundus
diseases.
（Fig.1） Retina waveform example 1
Retinal
pigment
epithelium
(Fig.2) Retina waveform example 2
Internal
limiting
membrane
Retinal pigment
epithelium
Sclera
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