Abstract
Purpose :
Retinopathy of pre-maturity (ROP) is one of the leading causes of child hood blindness in India. The screening programs for ROP India mostly use wide field hand held color contact fundus cameras. Recent studies have shown that 40% of children with ROP have incidence of macular edema which cannot be identified with these fundus cameras. It requires the Pediatric ophthalmologist to view the cross sectional view of the fovea which is possible by either an ultrasound b-scan or an Optical coherence tomography (OCT) machine. The ultrasound machines have poorer image resolution which may fail to identify small edematous conditions. Even though, there are several commercial table top OCT machine available in the market, it will require the baby to be held in the “flying baby position” to do the scan. We have now developed a hand held SD-OCT that can be used when the baby is in a basinet.
Methods :
We developed a SD-OCT at 840nm with a FWHM of 50nm. It has a movable reference arm to adopt for the variation in the axial length of the eye. The hand held probe has a collimator, Galvo scanner, scan lens and an ocular lens. We are able to achieve 39 degree FOV in an adult model eye. The scanning software has 2 options to fix the field of view, one being orthogonal b-scans and the other is a high speed enface image at much slower refresh rate. Once the FOV is fixed, the user has the option to get a radial scan or a c-scan of the retina in view.
Results :
We have successfully imaged the adult human fovea in a radial scan pattern (6 orientations separated by 60 degrees with fovea as the center). We have also imaged an adult disc with c-scan. Each b-scan has 500 a-scans and each c-scan has 128 b-scans.
Conclusions :
We are able to see the various retinal layers like the Retinal nerve fiber layer, Ganglion cell complex layer, inner plexiform layer, inner nuclear layer, outer plexiform layer, outer nuclear layer and other outer retinal structures. We are able to see the foveal dip and the cupping in the optic nerve head.
This is a 2020 ARVO Annual Meeting abstract.