Table 2.

Examples of misclassifications

Procedure to be classified as present or absent	Type of misclassification	Operation note	Gold-standard coding
42702	False positive	Right IOL rotation to 1 degree Prep drape Mendez ring used to assess the current IOL axis position Main incision from previous surgery at 35 degrees Main incision reopened using keratome Viscoelastic used to open the capsular bag, no issues IOL rotated to a new position at 1 degree IOL axis confirmed with Mendez ring Aspiration irrigation of viscoelastic Incision hydrated Cefazolin 1 mg/0.1 mL into the AC. Incision stable Chlorsig and maxidex to the right eye Pad and shield	42704
42725	False positive	LE Vitritis? PCNSL – LE Phaco/IOL/25GPPV/Vitreous Biopsy LE Routine Phaco + IOL (small pupil) 3 × 25 G ports in vitreous biopsy PVD present, checked with triamcinolone Int search, ports out SC Cef and Dex Pad	42702 42738 42740
42809	False positive	Right Cataract and Diabetic VH-RE Phaco/IOL/PPV/Laser/Avastin Eye cleaned and draped Routine phaco + IOL 3 × 25 G ports in PPV. pvd present Internal search Fill in PRP Partial fax IVI Avastin Ports out. SC Cef and Sex Pad Intraop findings: VH, no areas of traction or obvious NVD/NVE	42702 42725 42740 42809
42740	False positive	R phaco + IOL with Iris hooks without complications Cefazolin IC 0.05 kenacort intravitreal	42702 42740
42746	False positive	Nil	N/A
42702	False negative	LE cataract + SiO filled eye post RD + CMO – LEPhaco/IOL/Removal of SiO/IVTA Eye prepped with Betadine and draped 2 corneal incisions made, synechiolysis with cannula and viscoelastic Anterior capsule stained with brilliant blue, 5x iris hooks Capsulorrhexis, hydrodissection Phacoemulsification of nucleus, removal of cortex with IA probe IOL into bag 3 × 25g ports in, removal of SiO, multiple FAX, IVTA 0.1 mL Removal of iris hooks, removal of Viscoelastic, sclerotomy closed with Vicyl 7/0, IC Cef Hydration of self-sealing Corneal wounds, SC Cef and Dex Eye cleaned, pad and shield	42702 42725
42725	False negative	Eye prep with Betadine and draped 360 conjunctival peritomy, recti muscles isolated and slinged Scleral buckle applied and sutured to sclera with Nylon 5/0 Corneal sections, 4 x iris hooks, phacoemulsification, no lens injected 3 × 25 G 6 mm ports inserted Funnel retinal detachment, with giant retinal tear temporally Vitrectomy with base dissection with the assistance of triamcinolone stain, membranes stained with membrane blue and peeled 360 retinectomy done close to the arcade vessels after 360 endodiathermy Dislocation of macula, tried repositioning with tano brush, PFCL to flatten the retina, FAX, Endolaser 360, Reformation of AC with BSS, iris hooks removed Silicone oil 5500 cst injected, sclerotomy closed with Vicryl 7/0 Scleral buckle removed Conj closed with Vicryl 7/0 Subtenon ropivacaine 0.5% 5 mLs RE examined with BIO with indentation, 2 areas of retinal tear, lasered from before. no new breaks	42776 42698 42725 42740 42809
42809	False negative	Left PDR with VH and TRD-LE PPV/Laser/Segmentation/Avastin/SiO 1,300 cst Eye prep with Betadine and draped 3 × 27 G ports inserted, PVD not present Vitrectomy, segmentation of tractional membranes Intraop findings: solitary tractional membrane nasal to disc, broad tractional membrane superiorly with massive exudations subretinally extending to 1/2 disc diameter from fovea. No breaks PRP laser Fluid-air exchange, intravitreal avastin, Silicone Oil 1300 cst injected Ports out, no leak from sclerotomy Subconj Cef and Dex Eye cleaned, pad and shield applied	42725 42809
42740	False negative	R eye 25g PPV + laser +air for VH secondary to PDR 3 ports in PPV + PVD checked with triamcinolon Tag on superior arcade and nasally to a bifrovascular old pannus not bleeding 360 search laser top up inferiorly and temp FAX AVASTIN ic 3 ports out/sealed Cef and Dex subconj	42725 42740
42746	False negative	RIGHT trabeculectomy with mitomycin C 0.02% Betadine prep, drape, and speculum (Ong) Superior peritomy, conjunctiva and tenon’s capsule undermined MMC soaked sponge applied for 2 min Saline irrigation to area Cautery to scleral vessels 4 × 3 mm half thickness square scleral flap Paracentesis Trabeculectomy with Kelly punch. Peripheral iridectomy with de Wecker scissors 10-0 nylon to flap BSS to reform AC – flap filtering. 10-0 nylon to close conjunctiva – wound secure Subconj dexamethasone Atropine Pad and shield	42746