Description

Study Rationale and Clinical Significance The increasing demand for spectacle independence following cataract surgery has driven the development of advanced intraocular lens (IOL) technologies that extend beyond traditional monofocal designs. This prospective comparative study addresses a critical gap in understanding the real-world performance of contemporary extended depth-of-focus (EDOF) IOLs versus premium monofocal lenses.

Intermediate Vision Focus: Modern lifestyle demands have elevated the importance of intermediate visual function, particularly for distances between 60-80 cm, which encompass critical daily activities including computer work, dashboard viewing, kitchen tasks, and tablet reading. Traditional monofocal IOLs inherently limit functional vision to a single focal distance, necessitating spectacle dependence for intermediate and near visual tasks. This study specifically evaluates how different optical approaches address this intermediate vision gap.

EDOF Technology Principles: The study examines five distinct optical strategies for extending depth of focus: wavefront-shaping technology (AcrySof IQ Vivity), progressive power profiles (TECNIS Eyhance), refractive aberration manipulation (LuxSmart), continuous transition diffractive optics (Rayner EMV), and spherical aberration modulation (Eycryl SERT). Each represents a different approach to creating an elongated focal point rather than discrete foci, theoretically providing enhanced intermediate performance while minimizing visual disturbances associated with multifocal designs.

Study Design and Methodology Design Framework: This prospective, single-center, comparative clinical trial employs a patient-preference methodology rather than traditional randomization. This approach reflects real-world clinical practice where IOL selection involves shared decision-making between surgeon and patient based on individual visual needs, lifestyle requirements, and risk tolerance.

Patient-Preference Rationale: The patient-preference design was selected to: (1) respect patient autonomy in premium IOL selection, (2) minimize ethical concerns associated with randomizing patients to potentially suboptimal treatments based on individual needs, and (3) generate clinically relevant real-world evidence regarding patient-chosen outcomes and satisfaction levels.

Surgical Standardization: All procedures are performed by a single experienced surgeon using standardized phacoemulsification technique with identical surgical parameters: 2.5mm superior corneal incision, 5.5mm continuous curvilinear capsulorhexis, horizontal chop phacoemulsification, and bilateral same-model IOL implantation. Target refraction aims for emmetropia with slight myopic bias.

Primary Assessment Domains Intermediate Visual Performance Distance-Specific Testing: The protocol emphasizes comprehensive intermediate visual assessment at two critical distances: 80cm and 60cm. These distances represent distinct functional zones - 80cm corresponds to automobile dashboard and extended arm's length tasks, while 60cm represents standard computer monitor and kitchen counter distances.

Measurement Methodology: Both uncorrected intermediate visual acuity (UIVA) and distance-corrected intermediate visual acuity (DCIVA) are assessed monocularly and binocularly under standardized photopic conditions (85 cd/m²) using high-contrast charts. Multiple chart sets prevent memorization effects across repeated assessments.

Clinical Significance Threshold: The study is powered to detect clinically meaningful differences of 0.1 logMAR in DCIVA, representing approximately one line of visual acuity improvement that translates to functional benefits for intermediate tasks.

Defocus Curve Analysis Defocus curve: Binocular defocus curve testing employs defocus lenses from +1.50D to -2.50D in randomized order, corresponding to simulated viewing distances from infinity to 40cm.

Depth of Focus Quantification: Two threshold levels (0.1 and 0.2 logMAR) define depth of focus as the dioptric range from 0.00D defocus to the largest negative defocus value maintaining threshold visual acuity. This methodology provides standardized assessment of extended focal range capabilities across IOL technologies.

Functional Vision Range: The defocus curve demonstrates each IOL's usable vision range, identifying optimal performance zones and transition points where visual quality degrades.

Contrast Sensitivity Assessment Multi-Condition Testing: Contrast sensitivity evaluation employs the Functional Vision Analyzer across five spatial frequencies (1.5, 3.0, 6.0, 12.0, and 18.0 cycles per degree) under three standardized lighting conditions: photopic (85 cd/m²), mesopic (3.0 cd/m²), and mesopic-with-glare (3.0 cd/m² background with 28 lux glare source).

Real-World Simulation: The three testing conditions simulate actual visual environments: photopic represents daylight conditions, mesopic simulates twilight or indoor lighting, and mesopic-with-glare replicates challenging scenarios such as night driving with oncoming headlights.

Patient-Reported Outcomes

Validated Questionnaires: Two established instruments assess subjective visual experience:

Visual Function Index-14 (VF-14): Evaluates functional visual performance across 14 daily activities including reading, driving, recognizing faces, and performing fine tasks. Each item scores 0-4 with responses weighted by individual importance, generating a 0-100 scale where higher scores indicate better visual function.

McAlinden's Quality of Vision: Assesses patient-reported visual symptoms including glare, halos, starbursts, hazy vision, distortion, and focusing difficulties. Three Rasch-tested scales measure symptom frequency, severity, and bothersome impact on daily activities.

Spectacle Independence Assessment: Comprehensive evaluation of spectacle dependence across distance, intermediate, and near tasks, with particular emphasis on complete spectacle independence rates and task-specific visual function.

Statistical Methodology Sample Size Calculation: Power analysis targets detection of 0.1 logMAR differences in DCIVA with 90% power and α=0.05, accounting for 10% attrition, requiring 200 eyes (25 patients per group).

Analysis Approach: Generalized linear modeling with inverse Gaussian regression and identity link accommodates logMAR data characteristics.

Multiple Comparison Control: Sequential Bonferroni correction controls Type I error while maintaining statistical power, with the monofocal CT ASPHINA 409M serving as the reference comparator for all pairwise analyses.

Clinical Assessment Timeline Preoperative Evaluation: Comprehensive baseline assessment includes biometry, corneal tomography, specular microscopy, optical coherence tomography, and complete ophthalmologic examination to ensure optimal surgical candidacy and establish baseline parameters.

Postoperative Follow-up: Standardized assessments at 1 day, 1 week, 1 month, and 3 months postoperatively. Primary endpoints are assessed at 1 and 3 months to capture visual stabilization and adaptation effects.

Safety Monitoring: Continuous assessment of IOL stability, posterior capsule opacification development, and complication rates throughout the follow-up period.

Innovation and Clinical Impact This protocol represents the first comprehensive head-to-head comparison of four contemporary IOL technologies using standardized methodology and validated outcome measures. The emphasis on intermediate visual performance, quantitative depth of focus analysis, multi-condition contrast sensitivity assessment, and patient-reported outcomes provides clinically relevant data for evidence-based IOL selection and patient counseling in modern cataract surgery practice.