Size Matters: A practical guide to measuring optic disc size and its importance in diagnosing glaucoma for the eye care professional

Background: This research study explores the relationship between optic disc, cup, and
neuroretinal rim size and its correlation with glaucoma. There is a specific focus on the
use ofa slit-lamp and condensing lens as a method for the measurement and estimation of
the size ofthe optic disc. Through this research a clinical guide for practicing clinicians
will be made summarizing this infonnation and making it available in a format that can be quickly consulted in-office. Methods: Papers and abstracts of relevant studies for this review were obtained from PubMed, Science Direct, Ovid, Medline journals, as well as through interlibrary loans through Ferris State University and Wayne State University. The primary search terms used were: Optic disc size and relation to glaucoma,
Techniques for measuring optic disc size, Optic disc size variation among populations, and Ophthalmoscopic techniques for measuring optic discs. The search covered the years from 1988 to 2017. The criteria for inclusion or exclusion ofarticles were: the critical judgment ofcomparing different optic disc measurement techniques, the importance for the inclusion ofoptic disc variation among populations, and explanations for the relative risk ofglaucoma related to the size ofboth the optic disc and the optic cup. Results: Various studies have found that estimations of the optic disc size can be made using a slit-lamp and condensing lens. These studies have also found moderate correlation between measurements made at the slit-lamp, and those made with more precise office equipment such as the Heidelberg Retina Tomograph, and fundus photo planimetry. Conclusion: The use offundoscopic techniques is an efficient and cost-effective option to perform measurements ofthe optic nerve head while maintaining a high degree of accuracy. These measurements can be used to classify optic disc sizes into small, average, and large categories.