Effects of Retinopathy of Prematurity (ROP) on Intraocular Structures

Abstract

 

Purpose

 

Measure the effects of ROP on intraocular structures.

 

Methods

 

We reviewed extant magnetic resonance images (MRIs) obtained at Boston Children’s Hospital Department of Radiology from term- and preterm-born patients for images suitable for generation of high-resolution, coronal, pupil-optic-nerve sections. Selected subjects (n=161) were binned twice: 1) Into four postmenstrual age (in weeks) at birth and ROP status bins, ‘Group’ (‘Term’ ≥37; ‘Intermediate’ >32 to <37; ‘Premature’ ≤32 with no ROP, ‘ROP’ ≤32 with ROP), and 2) into four age (in years) at imaging bins, ‘Test Bin’ (<1; 1-3; 3-10; >10). Using software modified from our study of the rat eye (Chui et al., J Opthalmol 2012), on images of both eyes of every subject, we measured the axial positions of the anterior and posterior corneal surfaces (AC, PC), the anterior and posterior lens surfaces (AL, PL), and the inner retinal surface (Ret), among other features (see below). We fit growth curves, L=Lm●Ageⁿ/(Age_½ⁿ+Ageⁿ), to anterior chamber depth (ACD), posterior chamber depth (PCD), and axial length (AxL) of each Group to derive the age at which each reached half its adult length; lens thickness (LT) did not increase with age. For every eye, an ‘abnormality’ score was calculated for ACD, PCD and AxL by subtracting the value predicted by the Term subjects’ growth curve from the measured value. Finally, we derived anterior segment length (ASL) and respectively computed the ratios of ACD and ASL to PCD. All data were analyzed by ANOVA (Group×Test Bin×Eye) followed by Tukey’s HSD.

 

Results

 

For ACD, LT, PCD, and AxL, Term and Premature subjects did not significantly differ, but Term and ROP subjects did; importantly, ACD, PCD and AxL were lower in ROP eyes but LT was higher. Consequently, ACD/PCD did not differ within levels of Group but ASL/PCD was significantly higher in ROP subjects. Age_½ was later for ACD, AxL, and especially PCD in ROP compared to Term. 'Abnormality' in ACD, PCD and AxL were statistically indistinguishable in Term, Intermediate, and Premature but higher in ROP subjects.

 

Conclusions

 

Ocular abnormalities are increased more in ROP than in preterm birth alone.

 

 

The eye (green shaded region) and lens (blue shaded region) were segmented individually and the AC, PC, AL, PL and Ret surfaces detected (red lines). From these surfaces, the ACD and PCD (orange arrows), ASL (green arrow) and AxL (blue arrow) were measured.

 

Keywords: 497 development • 706 retinopathy of prematurity • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)