Axial and Posterior Wall Thickness Elastic Modulus of Eyes in Age-related Macular Degeneration (ARMD) Patients Compared to Healthy Individuals Using Ultrasound Images

Background & Aims: Age-related macular degeneration (ARMD) is one of the common retina disorders that can lead to loss of vision by increase in age. In this study, the efficacy of a non-invasive ultrasound technique for the evaluation of alastic properties of eye in the diagnosis of ARMD has been evaluated. Methods: For estimation of the elastic modulus of eye, spatial loading system designed and constructed. Then an external stress (۲۶۱۴±۱۴۶ Pascal) less than intraocular pressure of eye was applied to ۱۰ eyes belonged to ARMD patients and ۲۵ eyes belonged to age-matched control subjects. Ultrasound images of Bmode, A-mode and RF signals were taken before and after applying stress and saved in the computer by multimedia board. The scans were aligned vertically and placed at the temporal edge of the macula. After image processing the elastic properties were compared in the two groups. Relative changes of eye axial length, posterior wall thickness and retina-choroid were measured by ultrasound images. Based on applied stress, elastic modulus of eye axial length, posterior wall thickness and retina-choroid were estimated. Independent paired t-test analysis was used for comparison of the two groups. Results: There was a significant difference (P<۰.۰۵) in the eye axial length elastic modulus between the ARMD group (۱۰۹۱۰۰±۳۷۰۱۷ Pa) and control group (۶۳۹۲۰±۳۶۲۱۲ Pa). There was also significant difference (P<۰.۰۰۱) in elastic modulus of ocular posterior wall thickness between the ARMD group (۵۸۹۱۱±۱۵۸۸۴ Pa) and control group (۲۱۱۵۴±۱۳۱۱۶ Pa). While, there was no significant difference in retina-choroid complex axial elastic modulus between the ARMD group (۱۷۷۰۰±۳۶۷۵ Pa) and control group (۲۰۱۷۵± ۴۹۵۶ Pa). Conclusion: It is concluded that elastic modulus of eye axial length and posterior wall thickness can be used for differential diagnosis of eyes with ARMD.

Keywords:

Ultrasonography , Elastic modulus , Age-related macular degeneration (ARMD)