R R

What Is a Javal-Schiotz Axis?

A Javal-Schiotz axis is the direction of corneal astigmatism shown on a Javal-Schiotz keratometer reading. It is recorded as an angle from 0 to 180 degrees that lines up with the steep or flat corneal meridian. Eye doctors use the axis together with the curvature values to describe how the cornea is shaped. This information helps with toric glasses or contact lens planning and is also useful before some eye surgeries. The axis on keratometry can differ from the axis on a glasses prescription when astigmatism comes from inside the eye as well.

Link to This Resource Page

Provide a valuable resource to your clients or customers by linking to this resource page. Just place the following link on your website.

To display this...

What Is a Javal-Schiotz Axis?

A Javal-Schiotz axis is the direction of corneal astigmatism shown on a Javal-Schiotz keratometer reading. It is recorded as an angle from 0 to 180 degrees that lines up with the steep or flat corneal meridian. Eye doctors use the axis together with the curvature values to describe how the cornea is shaped. This information helps with toric glasses or contact lens planning and is also useful before some eye surgeries. The axis on keratometry can differ from the axis on a glasses prescription when astigmatism comes from inside the eye as well.

read more about javal-schiotz axis ...

Copy this HTML:

Copy HTML Copied!

What Does the Javal-Schiotz Axis Tell You About the Cornea?

Keratometry measures how curved the front surface of the eye is in different directions. When one meridian is steeper than another, that difference is corneal astigmatism. The axis marks the orientation of those meridians, so an eye doctor knows which direction is steepest. A Javal-Schiotz keratometer uses reflected light from mires to estimate curvature. The reading is usually written with two keratometry values plus the axis direction.

How Is the Axis Written on Keratometry Results?

Axis notation can look different depending on the printout, but common formats include:

  • A number from 0? to 180? that describes direction (for example, 090? or 180?).
  • Two principal meridians that are 90? apart (for example, 045? and 135?).
  • A ?steep? meridian and a ?flat? meridian, each with an associated direction.
  • A plus-cylinder or minus-cylinder style report, depending on the device or chart.
  • Notes like ?with-the-rule? or ?against-the-rule? when the steep meridian is near the vertical or horizontal.

Why Does Axis Matter for Astigmatism Correction?

Toric glasses and toric contact lenses need the axis to line up with the eye's astigmatism direction. If the axis is off, vision can stay blurry even when the power looks correct. Axis also matters when a contact lens rotates on the eye, since rotation can shift the correction away from the target meridian. Before cataract surgery or corneal procedures, axis information can guide astigmatism treatment planning. Because readings can vary a bit, an eye doctor often compares more than one measurement.

When Do Eye Doctors Use Keratometry Measurements?

Keratometry is common during routine vision exams, contact lens fittings, and pre-op checks. It can be used when astigmatism changes, after eye injury, or when vision blurs with the same glasses. Dry eye and corneal surface irritation can make readings less stable, so treating the surface first can improve accuracy. After refractive surgery or corneal disease, mapping tools like corneal topography can add more detail. An eye care professional chooses the test plan based on symptoms and eye health.

Frequently Asked Questions About Javal-Schiotz Axis

Is the keratometry axis the same as the axis on my glasses prescription?

Not always. Keratometry mainly reflects astigmatism from the cornea, while a glasses prescription includes both corneal and internal sources. If internal astigmatism is present, the axes can differ. An eye doctor looks at both measurements when choosing the best correction.

Can keratometry miss irregular astigmatism?

Yes. A standard keratometer measures only a small central area of the cornea, so irregular shapes can be missed. Corneal topography or tomography maps more points and can show irregular astigmatism patterns. If vision is still blurry with toric correction, an eye doctor may order those tests.

Do contact lenses change keratometry readings?

Contact lenses can temporarily change the corneal surface, especially rigid lenses that reshape the front of the eye. Soft lenses can also affect tear film and surface smoothness during wear. For the cleanest keratometry, a clinic may ask for a lens-free period before testing. The timing depends on lens type and the reason for the visit.

How often should keratometry be repeated?

There is no one schedule that fits every person. Keratometry is often repeated when a new contact lens fit is planned, when astigmatism seems to shift, or before surgery. Extra checks can also happen after corneal injury, infection, or refractive surgery. An eye doctor will suggest timing based on age, symptoms, and eye history.

References

1. Keratometry. Cleveland Clinic. https://my.clevelandclinic.org/health/diagnostics/24897-keratometry. Published November 14, 2024.

2. Keratometer. StatPearls (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK571350/. Last Update: June 11, 2023.

3. What Do Astigmatism Measurements Mean? American Academy of Ophthalmology. https://www.aao.org/eye-health/glasses-contacts/astigmatism-measurements. Published May 13, 2024.

4. Astigmatism. National Eye Institute. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/astigmatism. Last updated December 4, 2024.

5. Astigmatism. MedlinePlus. https://medlineplus.gov/astigmatism.html. Last updated June 1, 2024.