We selected common surgical procedures performed across ophthalmic subspecialties using payor claims data. ^, We then determined Medicare ASC and HOPD facility fee schedules by Current Procedural Terminology (CPT) code using publicly available data for San Diego County (region 41740) ( Table 1 ). The CPT codes used were the following: 66984 (extracapsular cataract removal with insertion of intraocular lens prosthesis), 66180 (aqueous shunt to extraocular equatorial plate reservoir), 15823 (blepharoplasty, upper eyelid), 68720 (dacryocystorhinostomy), 66170 (fistulization of sclera for glaucoma; trabeculectomy ab externo in the absence of previous surgery), 65750 (keratoplasty; penetrating), 67904 (repair of blepharoptosis; (tarso) levator resection or advancement, external approach), 67312 (strabismus surgery, recession or resection procedure; 2 horizontal muscles), and 67036 (vitrectomy, mechanical, pars plana approach). Physician professional fees were not included in this analysis because they do not contribute to operational or material expenses associated with ASCs or HOPDs.

Costs for each procedure were divided into direct material costs and indirect costs ( Table 1 , Supplemental Tables 2-10). Direct material costs included disposable items used during individual procedures, including gloves, sutures, syringes, etc. (Supplemental Materials). Complete inventory and unit prices were determined using institutional financial records. Costs related to implants, grafts, and other discretionary supplies were excluded from analysis because total expense is more likely to vary per procedure based on patient need and physician clinical judgment. Furthermore, for frequently used implants, such as monofocal intraocular lenses, unit cost varies widely by facility due to the use of group purchasing agreements and other direct manufacturer negotiations. Indirect costs included expenses related to equipment used to perform each procedure, including phacoemulsification machines, operating room microscopes, electrocautery devices, and more (Supplemental Materials). We determined indirect costs of equipment by using retail prices from manufacturer websites. To calculate the proportion of indirect costs attributed to individual procedures, we assumed a 7-year lifetime ^, for each piece of equipment based on standard maintenance schedules, using it 5 days per week, excluding holidays. Any expenses that could be reimbursed directly under separate CPT codes were excluded.

As this analysis focused exclusively on institutional procedural expenses for ASCs, we excluded personnel costs covered by Medicare professional or physician fees. The personnel costs that were included in our analysis were as follows: 1 scrub technician, 1 circulating nurse, 1 perioperative nurse, and 1 front desk coordinator. Annual compensation was determined using publicly available pay scales. All employees were assumed to work 5 days per week, excluding overtime, vacation, and holidays.

Operational costs for ASCs were determined based on the framework proposed by Childers and Maggard-Gibbons that analyzed financial disclosures from various types of hospitals in California to determine the cost of 1 minute of operating room time, adjusted for inflation to 2025 US dollars. In their analysis, they determined that total operating costs for ASCs consisted of direct costs (wages, benefits, supplies, and services related to maintenance) and indirect costs (costs not associated with departments, such as security). To estimate the total operational costs for the purposes of the present analysis, we included indirect costs and equipment maintenance expenses but excluded costs related to supplies and personnel because these were already accounted for. This figure was also used for the analysis of HOPDs because there was no significant difference found between the operational costs of ASCs and inpatient operating rooms associated with hospitals.

A visual representation of the approach used to calculate the maximum total intraoperative time to maintain financial neutrality using the cost figures mentioned previously is illustrated in Figure 1 .

Visual representation of calculation to determine total intraoperative time to maintain financial neutrality for ASCs and HOPDs. ASC = ambulatory surgical center; HOPD = hospital outpatient department.

Our model also allowed us to evaluate the impact of inflation, wage growth, and changes in the Medicare fee schedule on the maximum intraoperative time to maintain financial neutrality ( Figure 2 ). We analyzed 2 scenarios based on current Consumer Price Index statistics: 3.00% inflation for 5 years (to 2030), 0.00% wage growth, and no change in Medicare fee schedules (scenario 1); and 0.00% inflation, 4.00% wage growth for 5 years (to 2030), and no change in Medicare fee schedules (scenario 2). In these 2 scenarios, we excluded the impact of inflation on indirect costs associated with each procedure, as these purchases are made infrequently due to the lifespan of equipment and therefore are not as affected by inflation.

Visual representation of adjustments applied to calculation of maximum intraoperative time to maintain financial neutrality to calculate impacts of inflation, wage growth, and changes in Medicare fee schedule.

We analyzed the maximum intraoperative time to maintain financial neutrality for individual procedures compared with the sample mean. A 1-tailed t test was used to compare individual times to assess whether they were significantly lower than average, defining α of <0.05 as statistically significant.