A pachymeter is a piece of optical equipment used to measure the thickness of the cornea. A pachymeter proves useful for patients who may be developing, or there is a suspicion of, glaucoma. Pachymeters can also be used to perform corneal pachymetry before refractive surgery. Pachymeters are generally hand held pieces of optical equipment.
Pachymetry is a simple, painless test that quickly measures the thickness of the cornea.
Why Measure Corneal Thickness?
Corneal thickness as measured by pachymetry is important in the eye care field for several reasons.
Pachymetry can tell an optometrist or an ophthalmologist if the cornea is swollen. Medical conditions such as Fuch's Dystrophy can increase fluid in the cornea and cause an increase in overall thickness. Even wearing contact lenses can sometimes cause significant corneal swelling. This may be difficult to see under the microscope. However, pachymetry will show a definite increase in thickness.
Corneal thickness is extremely important in refractive surgical procedures such as LASIK. Knowledge of corneal thickness is important to determine if a person is a candidate for laser vision correction. Because part of the procedure includes removing tissue which will leave the corneal thinner, it is important to know exactly how much will remain. Some people may have a cornea that is just much thinner than normal. It does not cause problems or disease, but it could spell tragic vision loss if a refractive procedure is performed on someone whose cornea is extremely thin.
Pachymetry has also become important in glaucoma care. Glaucoma is a disease in which eye pressure (intraocular pressure) can be elevated. Elevated eye pressure can cause nerve fibre loss in the retina which may result in blindness or decreased vision. Most methods involve a method of measuring eye pressure in which the instrument touches the cornea. Researchers discovered that corneal thickness can vary slightly in the population. Corneal thickness can influence the actual reading of the amount of pressure in the eye.
How Pachymetry Is Performed?
Pachymetry can be performed by two methods, by ultrasound techniques or by optical techniques.
Ultrasound Pachymetry: Ultrasound pachymetry as the name implies, uses ultrasound principles to measure the thickness of the cornea. The 4Sight® from Accutome is made in the USA and designed with ophthalmologists in mind. It provides a single solution for ophthalmic diagnostics by combining an A-Scan, B-Scan, UBM and Pachymeter in one, easy-to-use platform.
Optical Pachymetry: Optical pachymeters vary on design. Some optical pachymeters are designed to be mounted onto a biomicroscope that eye doctors use called the slit lamp. Other devices can measure pachymetry using specular microscopy. This device does not come into direct contact with the cornea. One type of optical pachymetry that has gained in popularity is OCT or optical coherence tomography pachymetry. OCT pachymetry also does not touch the cornea to achieve the measurements. The MS-39 Anterior Segment OCT from CSO can perform this with ease and much more, find out more about this product on this website www.hansoninstruments.co.uk/cso/medical/anterior-diagnostics-treatments/cso-ms-39-anterior-segment-oct