Five-year vault dynamics in UBM-characterized flat ciliary body morphology: A case report on ICL V4c size optimization

Rationale: Conventional approaches for selecting implantable collamer lens (ICL) sizes, which are mostly based on white-to-white distance and anterior chamber depth, may be insufficient in eyes with abnormal ciliary body shape, such as ciliary body flatness. This case report demonstrates the importance of ultrasonic biomicroscopy (UBM) in recognizing this anatomical variance and guiding a more precise, personalized ICL size technique for excellent postoperative vault and long-term stability. Patient concerns: To get rid of his need for glasses, a 29-year-old man with stable moderate myopia wanted refractive surgery. Diagnoses: Bilateral myopia with astigmatism. Preoperative UBM revealed a flat ciliary body morphology, identifying him as a candidate at risk for suboptimal vault with standard sizing. Interventions: Following initial under-correction with a manufacturer-recommended 12.1 mm ICL in the right eye, which resulted in a critically low vault, both eyes were ultimately successfully implanted with 12.6 mm ICL. The left eye received this size primarily, while the right eye underwent an exchange procedure. Outcomes: Over a 5-year follow-up period following lens exchange, both eyes attained and maintained superior visual acuity (20/16). At 5 years, the final vault values showed long-term physiological positioning by stabilizing within the optimal range (OD: 241 μm, OS: 148 μm). Lessons: This case demonstrates that relying solely on white-to-white and anterior chamber depth can be misleading in eyes with a flat ciliary body. UBM is an essential preoperative technique for identifying this anatomy. Opting for a larger ICL size than the formulaically advised size and considering axial rotation can be helpful techniques for ensuring enough vault and avoiding problems, as indicated by the outstanding 5-year results presented here.