Simultaneous Measurements of Refraction and A-Scan Biometry During Accommodation in Humans

Authors

OSTRIN, LISA OD, PhD; KASTHURIRANGAN, SANJEEV PhD; WIN-HALL, DOROTHY OD; GLASSER, ADRIAN PhD, FAAO

Simultaneous Measurements of Refraction and A-Scan Biometry During Accommodation in Humans

publication date

April 3, 2006

Abstract/Introduction

Purpose.

Accommodation is a dioptric change in power of the crystalline lens resulting from ciliary muscle contraction that leads to an increase in lens surface curvatures and thickness and changes in the position of lens surfaces. Previous studies have used A-scan ultrasound to measure changes in the position of lens surfaces with voluntary accommodation, but have not simultaneously measured the change in refraction. The goal of this study is to simultaneously measure and correlate refractive and biometric changes in the lens during voluntary accommodation in humans.

Methods.

Refraction was measured off-axis in the right eye and biometry on-axis in the left eye simultaneously during voluntary accommodation in 22 human subjects between the ages of 21 and 30 years (mean ± standard deviation: 25.8 ± 2.3 years). Subjects viewed a distant target and four near targets spanning the full accommodative range available to evaluate refraction and lens surface position at each accommodative state.

Conclusion/Results

Results.

Maximum objectively measured accommodative amplitude of all subjects was 5.64 ± 0.21 D (mean ± standard error of mean). Biometric and refractive changes during accommodation were linearly correlated. The mean ± standard error of mean decrease in anterior chamber depth was 0.051 ± 0.008 mm/D, increase in lens thickness was 0.067 ± 0.008 mm/D, and increase in anterior segment length was 0.017 ± 0.005 mm/D during accommodation. There was a net anterior movement of the lens center of 0.017 ± 0.005 mm/D.

Conclusion.

Anterior chamber depth, lens thickness, and anterior segment length change linearly with refraction during accommodation. Per-diopter changes in the lens were greater in the current study compared with previous studies in which only accommodative demand was measured, which overestimates the accommodative response.

Testimonials

I haven't actually used the optometrist side, so my review is limited to the vision therapy offered. This office was recommended by my occupational therapist for the treatment of my double vision following a stroke.

Claire A.
Love this location. I had a brain injury accident from day one one. All the team make you feel you still important and hope in the horizon after when the medical system fell you miserably. Dr. Ikeda very professional and very understanding about your issue. Two tombs up.

Jim K.
My husband and I were immediately impressed with Dr Ikeda. I was hit by a car while cycling which caused broken bones and three brain injuries. The brain injuries caused double vision. Dr. Ikeda examined my eyes and got me started on vision therapy with his occupational therapist who specializes in vision therapy. She (Chris) is absolutely great. I am impressed with the array of tools used to help recover my binocular vision. I am doing things I never thought were possible (balance boards etc). Chris pushes me and keeps me motivated. I really enjoy my sessions with her. The office staff is always friendly and they have a wonderful appointment reminder tool that makes it easy to keep my calendar up to date. I am happy the rehab center at Little Co. of Mary recommended them!!

Teresa S.
The Vision Therapy is handled in a separate office through a different door from the shared waiting room. Chris, the vision therapist, has a wide and varied assortment of tools, equipment and resources to best evaluate and treat most vision issues. After just a few visits, my double vision became easier to control, using exercises developed during the therapy process. It was time well-spent.

Joe M.
I have been coming here since I can remember. I love it here. The staff is so amazing and nice. They explain everything they gonna do and never make you feel rushed. Dr. Ikeda has always been my doctor and I would never want another one. He is the doctor for my whole family and is always asking how everyone is doing. I am also so crazy about picking out my frames and have to try so many and each person who helps me take the time and lets me try them all on. I would never want to go anywhere else! I definitely would recommend this office to anyone looking for a great eye doctor.

Kayla W.