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Sir Harold Ridley implanted the first intraocular lens (IOL) in 1949.[1] Postoperatively, the patient had a refractive error of -18 dioptre sphere and -6.00 dioptre cylinder at 120 degrees. Later, Binkhorst introduced an 18.0 D pre-pupillary lens. It left the patient with the same refractive error he had before the cataract surgery. Thus, merely an implant is insufficient, and accurate IOL power calculation is necessary. It is 1 of the most critical factors for the refractive outcome of cataract surgery.[2] In most patients, emmetropia is the targeted post-operative refraction, while some patients are targeted for residual myopia.[3] To reach the targeted refraction, the selection of the IOL formula must be performed according to the anatomical and optical parameters of the eye. Axial length is an essential parameter in IOL power calculation. A change of 1 mm in axial length can alter the IOL power by 2.5-3.0D. Corneal power is another important factor. The cornea accounts for two-thirds of the total optical power. A change in corneal power by 1 Dioptre alters the IOL power by 1D.[4] Apart from the axial length and keratometry, other parameters, such as anterior chamber depth and the corneal white-to-white distance, may also be required.[5]
A patient with decreased vision due to cataracts presents to an ophthalmologist. If the patient requires cataract surgery, then the calculation of IOL power is necessary. The optometrist and the ophthalmologist should know all the generations of IOL power formulae. They should know their indications and where to use them. A-scan, keratometer, and optical biometer know-how are a must. The nursing staff, optometrist, and ophthalmologist should be conversant with the upkeep and usage of these instruments. Thus, interdepartmental communication ensures better patient management. The primary physicians can follow up with the postoperative patients. The nurses are the first medical staff to contact the follow-up patients. They can assess the postoperative refractive error and report any issues to the primary care clinician or the ophthalmologist. This collaborative, interdisciplinary approach to care can ensure better patient outcomes.