To prove medical necessity, you must get specific -- or risk denials Medicare covers IOL calculation procedures for patients about to undergo cataract surgery. But just listing 366.x (Cataract) as your diagnosis code will likely get your claim rejected. Below is a list of specific ICD-9 codes that many carriers recognize as demonstrating medical necessity for both 76519 (Ophthalmic biometry by ultrasound echography, A-scan; with intraocular lens power calculation) and 92136 (Ophthalmic biometry by partial coherence interferometry with intraocular lens power calculation): - 366.00-366.09 -- Infantile, juvenile and presenile cataract - 366.10 -- Senile cataract, unspecified - 366.13 -- Anterior subcapsular polar senile cataract - 366.14 -- Posterior subcapsular polar senile cataract - 366.15 -- Cortical senile cataract - 366.16 -- Nuclear sclerosis - 366.17 -- Total or mature cataract - 366.18 -- Hypermature cataract - 366.19 -- Other and combined forms of senile cataract - 366.20-366.23 -- Traumatic cataract - 366.30-366.34 -- Cataract secondary to ocular disorders - 366.41-366.46 -- Cataract associated with other disorders - 379.31-379.34 -- Aphakia and other disorders of lens - 743.30-743.39 -- Congenital cataract and lens anomalies - V43.1 -- Lens replaced by other means. Note: Always base your ICD-9 coding on the patient's condition, not on whether it will help your claim be paid, experts say.