Browse the corpus

Lensometry is a technique that measures the optical parameters of an ophthalmic lens. Lensometry may be performed using a lens clock or a manual, semi-automated, or automated lensmeter. Accurately measuring the dioptric power of prescribed lenses ensures patients with refractive errors receive the correct prescription lenses. Corrective lenses based on imprecise measurements can lead to visual disturbances and noncompliance. Patients will most likely achieve their best-corrected vision using prescribed lenses based on correct parameters obtained by trained ophthalmic healthcare professionals using precise and well-calibrated instruments. This activity reviews the indications, necessary equipment, and procedural technique of lensometry and highlights the role of the interprofessional team in ensuring that patients with refractive errors receive the correct prescriptive lenses. Objectives: Compare and contrast the benefits and drawbacks of manual, semi-automated, and automated lensmeters. Employ the steps of transposition to calculate a cross-cylinder prescription. Apply best practices when performing lensometry. Develop and implement effective interprofessional ophthalmic team strategies to ensure the best-corrected vision for patients requiring lenses for refractive errors. Access free multiple choice questions on this topic.

Lensometry measures the strength and prescription of eyeglasses or contact lenses using a lensmeter, an instrument sometimes referred to as a focimeter, vertometer, or Lensometer™. The two common indications for lensometry are the measurement of the power of spectacles during an ophthalmic examination and the verification of spectacle prescriptions created in an optical laboratory.[1] Lensometry is based on the concept of lens neutralization, which states that the resultant power of a lens system is equal to the power required to neutralize its properties towards a net value of zero. The inbuilt lenses of a lensmeter are an adjustable collimator.[2] Lensmeters may be manual, semi-automated, or fully automated.[3][4] The lensmeter makes it possible to measure the dioptric vertex power, optical center, cylindrical axis, and prism of a lens; some lensmeters can also measure the amounts of tint, light transmission, and ultraviolet transmission of a lens. This activity reviews the indications, contraindications, necessary preparation, technique, and clinical significance of lensometry while highlighting the role of the interprofessional eye care team in caring for patients who use lenses to correct refractive errors.

The lensmeter measures the power and characteristics of ophthalmic lenses used to correct refractive errors of binocular vision. Spectacle and contact lens corrections remain commonplace despite the availability of corrective refractive surgical procedures such as laser-assisted in situ keratomileusis (LASIK), laser-assisted subepithelial keratectomy (LASEK), and photorefractive keratectomy (PRK).[16][17] Refractive errors are the most common reason patients seek ocular care.[18] Lensometry confirms prescription powers before dispensing and neutralizes the powers of unknown lenses.[19] All ocular care providers must have a lensmeter, and staff must be appropriately trained in its use. The lensmeter is used in the assembly and confirmation of lens prescriptions to ensure the best-corrected vision for the patient.