Development of a Novel Eye Model to Teach Direct Ophthalmoscopy

Abstract

Purpose:: Direct ophthalmoscopy (DO) is an essential clinical skill for many medical specialties in accurate and early diagnosis of many systemic and ocular conditions. However, multiple studies reveal that most medical students lack skill in performing DO. Analysis showed that limited clinical experience and minimal curricular and faculty time were key factors leading to this deficit. Other factors included the use of eye models, with limits in anatomic similarity to the real fundus, the range of pathology exhibited and student accessibility to models due to high costs and complex assembly. Using a novel approach based on initial analysis of the factors essential to learning DO, we designed a new eye model to facilitate DO training.

Methods:: The principal elements of DO were identified and divided into structural, functional, content and assessment components by an experienced ophthalmoscopist. Structural factors identified included size similar to the human eye, variability of the pupil size, simplicity of construction and the ability to use an upright examining position. Key functional features included the need to vary the focus and the use of the ophthalmoscope illumination (as opposed to a backlit slide) as well as a curved anterior surface. Content features included the use of "real" images for training and the display of a broad range of pathologies. Assessment features required were the ability to create images with numerically and spatially quantifiable "findings". The efficacy of each feature was examined in a series of trials using experienced ophthalmoscopists and trainees.

Results:: Experiments showed that high resolution laser printed digital fundus images mounted on the back of truncated plastic spheres produced the most realistic images as compared to other media. Use of a flat image surface at a short distance forced the examiner to use variable focus. Using digital imaging technology (DIT), standardized training and testing images could be constructed by adding quantifiable pathologic findings onto normal images. A simple wall mount system allowed for an upright examination position. Simulation of the crystalline lens (up to +50D) did not significantly affect the examination process.

Conclusions:: A new eye model combining proactively identified parameters, DIT, standardized quantitative image generation and counterintuitive physical properties, exhibits all of the features identified as critical to the effective teaching of DO. This model should greatly facilitate DO training for all health care professionals.

Keywords: anatomy • learning • retina