Table 1.

ICD-9 and CPT Codes Used in this Study

Diagnosis/Procedure	ICD-9 or CPT Code
Keratoconus	371.6x
Corneal Disease	371.0x–371.5x, 371.7x–371.8x
Comorbid Conditions
Allergic rhinitis	477.0x, 477.2x, 477.8x, 477.9x
Asthma	493.xx
Dementia	290.xx, 294.1x, 331.2x
Depression	296.xx
Diabetes	250.xx, 362.01–362.07
Down Syndrome	758.0x
Hyperlipidemia	272.xx
Sleep apnea	327.2x, 780.51, 780.53, 780.57
Cataract	366.0x–366.4x, 366.8x, 366.9x
Macular degeneration	362.51, 362.52, 362.57
Primary open angle glaucoma	365.1x
Pseudophakia/aphakia	V431, 379.3, 379.3
Penetrating Keratoplasty	65730, 65750, 65755
Lamellar Keratoplasty	65710