Abstract Background: Slit-lamp biomicroscopy using a 90-diopter (90D) lens remains the gold standard for high-resolution stereoscopic examination of the posterior pole. Despite its routine use, many postgraduate trainees face difficulty achieving stable focus, adequate illumination, and confident interpretation of subtle retinal findings such as early neovascularization of the disc (NVD) and clinically significant macular edema (CSME). Purpose: To demonstrate a stepwise, reproducible technique for 90D slit-lamp examination of the posterior pole, focusing on optimizing optics, ergonomics, and illumination for improved detection of early diabetic retinopathy changes. Synopsis and Key Highlights: The video outlines patient positioning, beam alignment, and dynamic focusing for evaluating the disc and macula. A magnification table comparing 90D, 78D, and 60D lenses is included for quick reference. Practical nuances—reduced illumination, maintaining lens stability, and reflection control—are highlighted to help trainees refine technique and confidence during slit-lamp posterior pole evaluation. Conclusion: Systematic use of the 90D lens enhances diagnostic accuracy for macular edema, neovascularization, and posterior pole pathology. With practice, it becomes a powerful extension of slit-lamp examination.
Shah et al. (Thu,) studied this question.