Nasotemporal Asymmetry of Retinopathy of Prematurity

Abstract

To quantify an apparent nasotemporal asymmetry in the location of retinopathy of prematurity with respect to the optic disc. Methods: Twenty-four-bit color images were captured using a contact digital fundus camera during routine screening. Semiautomated measurements were undertaken to determine the distance between the optic disc and retinopathy located in the nasal and temporal regions of the retina. Results: Forty-nine image pairs (17 right eye, 32 left eye) were captured from 10 infants during a period of 32 to 40 weeks postmenstrual age. For right eyes, averaged across age, the mean (SD) distance between the optic disc and temporal retinopathy was 426 (26) pixels and that between the optic disc and nasal retinopathy was 330 (26) pixels. Corresponding measurements for the left eye were 428 (30) and 332 (24) pixels. This observed asymmetry was found to be statistically significant in both left and right eyes (Mann-Whitney U test, PϽ.01). While the distance between the optic disc and retinopathy increased with age by 10 to 17 pixels per week, the extent of the asymmetry did not vary systematically with age. Conclusion: The location of retinopathy of prematurity is asymmetric along the horizontal meridian with respect to the optic disc-an observation germane to retinal vascular development, the pathogenesis of retinopathy of prematurity, and current disease classification by circular (symmetric) zones.

Variation in rates of severe retinopathy of prematurity among neonatal intensive care units in the Australian and New Zealand Neonatal Network

“…At present it is not straightforward or practical for independent observers to audit the results of individual indirect ophthalmoscopy examinations, although the development and availability of contact digital retinal cameras may change this situation in the future. 20 However, the NICUs in the ANZNN are all served by experienced ophthalmologists, who follow explicit examination standards guidelines, 13 14 which should help to minimise this source of variation.…”

International Classification of Retinopathy of Prematurity, Third Edition

“…8 The location of retinal vascularization provides an indication of infant maturity and risk of ROP developing. The developing vasculature is lobular and closer to the optic disc nasally than temporally, 9 but as a practical matter, the state of vascularization (i.e., the zone) is recorded as circles with the optic disc at the center.…”

The effect of oxygen saturation targeting on retinal blood vessel growth using retinal image data from the BOOST-II UK Trial

“…This is consistent with a previous study. 14 ROP frequently develops first in the nasal retina in the most immature infants. 15 The mean PMA at which nasal measurements were made was 3 days earlier than for temporal measurements.…”

“…We chose an anatomically consistent reference point in relation to the temporal vessel arcades in order to reduce variation based on asymmetry of the extent of temporal retina vascularisation. An alternative approach would have been to make measurements at multiple points along the ROP ridge, as was done in the study by Gallagher et al 14 …”