The Uses of Corneal Pachymetry

The Uses of Corneal Pachymetry

ALEXANDRIA, VA – The corneal pachymeter, or measure of thickness, is a tool no eye doctor should go without. The pachymeter measures the thickness of a patient’s corneas, a quantity that may seem irrelevant to vision but is critical to understanding deeper ophthalmic issues. A pachymeter uses optical biometrics or ultrasonic waves to report the thickness of the cornea. Here are some of the uses of corneal pachymetry and how ophthalmologists and optometrists rely on an accurate measurement of this small but important part of the human eye.

Prior to LASIK Surgery

Refractive eye surgery, commonly known as LASIK, relies on successful ablation of the cornea to improve eyesight without necessitating contact lenses or eyeglasses. While LASIK has represented a breakthrough in ophthalmology, the variations in corneal thickness among LASIK candidates can preclude some patients from going through with the surgery. Most ophthalmologists will require a pachymetry reading of at least 500 micrometers, or 500 millionths of a meter, before proceeding with refractive surgery. Insufficient corneal thickness can lead to a condition known as post-LASIK ectasia, where a remodeled cornea causes myopia or astigmatism, undoing the intended benefits of the procedure.

Adjunct To Glaucoma Testing

Screening for glaucoma requires as accurate a reading of intraocular pressure, or IOP, as possible. However, above-average corneal thickness can provide additional resistance to a tonometer, indicating higher intraocular pressure than is accurate. Conversely, the cornea can be too thin, as in the case of patients disqualified from refractive surgery. In this case, a tonometer will underreport intraocular pressure, which can allow that pressure to build and cause optic nerve damage. Using a pachymeter to attempt to correct this misreading can assist ophthalmologists in obtaining greater IOP accuracy.

Extended-Wear Contact Lens Maintenance

Following cataract surgery, patients are left naturally aphakic, or without lenses. Today, most cataract patients receive an implanted artificial lens, but those who are not ideal candidates for implantation must rely on extended-wear contact lenses. Such patients can suffer from corneal edema as a result of prolonged contact with the cornea, leading to blurred vision. Determining whether this is the case makes up another of the uses of corneal pachymetry. By comparing corneal thickness measurements, an eye doctor can confirm that the cornea is swelling due to the extended-wear lenses, and perhaps recommend removing the lenses before bed.