The proportion of eyes achieving postoperative spherical equivalent (SE) within ±0.5 D and ±1.0 D of intended refraction is a core quality metric for biometry and refractive services. The Royal College of Ophthalmologists (RCOphth) 2021 guidance recommends departments personalise IOL A constants based on continuous outcome audit to eliminate systematic bias. Published series report 72–92% within ±1.0 D depending on biometry type, formula, and A constant customisation. This study reports baseline refractive performance at Narinder Mohan Hospital using contact ultrasound A scan and manufacturer A constants, provides statistical estimates for primary outcome measures, and makes pragmatic recommendations to convert audit findings into sustained quality improvement.

Study design and setting Retrospective consecutive case series of routine phacoemulsification operations performed at Narinder Mohan Hospital, Mohan Nagar, Ghaziabad, between 1 September 2022 and 30 August 2023. Data extraction and analysis were performed in September 2023. Participants and eligibility Included consecutive eyes of patients aged ≥40 years undergoing uncomplicated small incision phacoemulsification with in the bag foldable acrylic IOL implantation, who attended for six week postoperative subjective manifest refraction and achieved corrected distance visual acuity ≥6/12. Excluded eyes with preoperative corneal or retinal pathology expected to affect refraction, intraoperative complications, combined procedures, or lost to follow up before six weeks. Reasons for exclusion and counts were documented during data extraction. Biometry, IOL calculation and surgery Preoperative axial length was measured using contact ultrasound A scan (Sonomed A scan, Sonomed, USA) as recorded in the departmental biometry register. Keratometry and anterior chamber depth were recorded per routine clinical practice. IOL power calculations used the Regression 2 formula and manufacturer provided A constants (baseline practice). Routine small incision phacoemulsification was performed under topical or local anaesthesia with in the bag implantation of foldable acrylic IOLs. The principal IOL models implanted during the audit period were: Biotech EyeAcryl ASHFY 600 (Biotech, India); Biotech Genesis (Ireland); and Bausch & Lomb Envista (Bausch & Lomb). Surgical technique, postoperative regimen and follow up schedule were consistent during the audit period. IOL model and biometry operator for each case are recorded in the biometry register . Outcome measures and data collection Primary outcome: proportion of eyes with postoperative SE within ±1.0 D of the predicted refraction at six weeks. Secondary outcomes: proportion within ±0.5 D, mean absolute error (MAE) between predicted and achieved SE, SD and 95% CIs. Achieved refraction was manifest subjective refraction performed at six weeks per department protocol. Data were deidentified and extracted from clinical records and the biometry register into an audit dataset. Statistical analysis Descriptive statistics reported as counts (%) and mean ± SD. Proportions for ±0.5 D and ±1.0 D presented with 95% CIs computed by standard normal approximation (SE = sqrt[p(1−p)/n]; 95% CI = p ± 1.96·SE). MAE reported with SD and 95% CI (95% CI for mean = mean ± 1.96·SD/√n). No formal a priori sample size calculation was performed; sample size determined by consecutive cases during the audit period. Subgroup analyses by axial length categories (<22.0 mm, 22.0–24.5 mm, >24.5 mm), and by major IOL models were planned for subsequent reports where numbers permit. Audit governance and ethics Conducted as a clinical audit under local institutional governance at Narinder Mohan Hospital. Audit protocol and anonymised dataset are retained per institutional policy. Individual patient consent for anonymised audit reporting was not required by local policy.

Sample and baseline characteristics A total of 182 eyes met inclusion criteria. Baseline demographic and ocular characteristics are shown in Table 1. Refractive outcomes (baseline with manufacturer A constants) Proportion within ±1.0 D of predicted SE: 144/182 (79.12%; 95% CI 73.2–85.0). Proportion within ±0.5 D of predicted SE: 100/182 (55.0%; 95% CI 47.8–62.2). Mean absolute error (MAE): 0.65 ± 0.30 D (95% CI 0.60–0.70). Interpretation of baseline performance Baseline performance using manufacturer A constants fell short of an aspirational departmental benchmark of ≥85% within ±1.0 D. The distribution of errors and MAE suggested that a scalar adjustment of A constants based on local outcomes is likely to reduce systematic bias and improve the proportion within target. Tables Table 1 — Baseline demographics and ocular parameters (n = 182) Variable Value Age (mean ± SD) 68.2 ± 9.4 years Gender (Male / Female) 102 (56%)/80 (44%) Laterality (Right / Left) 94 (52%)/88 (48%) Axial length (mean ± SD) 23.45 ± 1.12 mm Anterior chamber depth (mean ± SD) 3.12 ± 0.45 mm Average keratometry (mean ± SD) 43.25 ± 1.75 D Table 1 Variable Value Age (mean ± SD) 68.2±9.4 years Gender (Male / Female) 102 (56%)/80 (44%) Laterality (Right / Left) 94 (52%)/88 (48%) Axial length (mean ± SD) 23.45±1.12 mm Anterior chamber depth (mean ± SD) 3.12±0.45 mm Average keratometry (mean ± SD) 43.25±1.75 D Table 2 — Refractive outcome summary (n = 182) Table 2 Variable Value Age (mean ± SD) 68.2±9.4 years Gender (Male / Female) 102 (56%)/80 (44%) Laterality (Right / Left) 94 (52%)/88 (48%) Axial length (mean ± SD) 23.45±1.12 mm Anterior chamber depth (mean ± SD) 3.12±0.45 mm Average keratometry (mean ± SD) 43.25±1.75 D Outcome Value Within ±1.0 D (n) 144/182 (79.12%; 95% CI 73.2–85.0) Within ±0.5 D (n) 100/182 (55.0%; 95% CI 47.8–62.2) MAE (mean ± SD) 0.65 ± 0.30 D (95% CI 0.60–0.70) Figure 1 — Distribution of spherical equivalent prediction error Caption: Histogram of achieved minus predicted spherical equivalent (SE) at six weeks (bin width 0.25 D) with overlaid cumulative distribution curve showing proportions within ±0.25 D, ±0.5 D and ±1.0 D. (High resolution PNG/TIFF to be supplied on submission.)

Key findings and context This original research report describes baseline refractive precision after routine phacoemulsification using contact ultrasound A scan biometry and manufacturer A constants: 79.1% of eyes were within ±1.0 D and MAE was 0.65 D. These results align with published series where non customised constants and contact ultrasound are used but are below the ≥85% benchmark many services aim for after optimisation. Practical implications and recommended actions Implement routine local A constant optimisation using consecutive outcome data and simple scalar corrections to eliminate systematic offset. Prospectively collect biometry and refractive data in a standardised electronic dataset to enable regular (annual) reaudit. Where budget and logistics permit, transition to immersion or optical biometry (partial coherence interferometry) and consider modern formulae (Barrett Universal II, Kane, Hill RBF) to reduce random and systematic error. Plan subgroup analyses by axial length strata, IOL model, and surgeon to determine whether model specific or surgeon specific constants are required. Strengths and limitations Strengths: consecutive case inclusion, prespecified outcomes, uniform postoperative timepoint for refraction, and pragmatic applicability for resource constrained settings. Limitations: retrospective single centre design; use of contact ultrasound A scan with device/model recorded only in the biometry register; absence of subgroup stratification in this baseline report; no direct comparison with immersion/optical biometry or contemporary formulas in the current dataset. Future work Report the outcome of the A constant customisation cycle (planned reaudit April 2024–March 2025) as a follow up comparative original research article, presenting before/after proportions and statistical testing to demonstrate effect size and sustainability.

Baseline refractive outcomes for routine phacoemulsification at our centre using contact A scan biometry and manufacturer A constants achieved 79.1% within ±1.0 D and MAE 0.65 D. Local A constant optimisation, improved biometry, prospective outcome collection, and annual reaudit are recommended to achieve an institutional benchmark of ≥85% within ±1.0 D. Declarations Ethics and audit governance: Conducted as a clinical audit under institutional governance at Narinder Mohan Hospital; anonymised audit record retained. Local audit approval reference is available on request. Individual patient consent for anonymised audit reporting was not required per local policy. Conflict of interest: The author declares no conflict of interest. Funding: No external funding. Acknowledgements: Audit assistants, data clerks, and colleagues who supported data collection (to be listed). Author contributions (CRediT): Conceptualization; Data curation; Formal analysis; Investigation; Methodology; Writing — original draft; Writing — review & editing: Dr Muneesh Kapoor. Data availability: Deidentified aggregate data used for analysis are retained by the department; individual patient data are not publicly available to protect confidentiality but can be shared on reasonable institutional request subject to governance.

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