From Tennent Institute of Ophthalmology (HCR, PKA, JEAS), Gartnavel General Hospital; and the Department of Ophthalmology (RJCB, GND), Royal Hospital for Sick Children, Glasgow, United Kingdom.
Presented as a poster at the Royal College of Ophthalmologists Annual Congress, May 19–21, 2009, Birmingham, United Kingdom.
The authors have no financial or proprietary interest in the materials presented herein.
The authors thank Peter Russell for consenting to serve as the subject of Figure 2C.
Address correspondence to Heather C. Russell, MBChB(Hons), Tennent Institute of Ophthalmology, Gartnavel General Hospital, Glasgow G11 6NT, United Kingdom.
The term “leukocoria” means white pupil. This may be observed clinically as a white pupil in ambient lighting or as a white, rather than red, reflex. The discovery of leukocoria in a child has important implications because of the significance of many of the possible underlying causes.
This series documents the findings of eight cases of unilateral and one case of bilateral leukocoria seen in off-axis digital flash photographs, with subsequent normal eye examination results. The mechanism underlying this phenomenon is discussed and its reproducibility under the correct conditions is demonstrated.
All cases presented to the pediatric ophthalmology department over a 6-month period. Details of the cases, obtained by retrospective review of the case notes, are summarized in the table. In all cases of unilateral leukocoria, the leukocoria was seen in the adducting eye (Figs. 1A–1C). In the bilateral case, the child was fixating a near target causing convergence of his eyes and was face on to the photographer (Fig. 1D). Of note, cases 1 and 8 were both the children of physicians and the discovery of unilateral leukocoria in photographs had caused considerable parental concern and anxiety due to some knowledge of the possible underlying causes.
Table: Summary of Cases of Leukocoria
Figure 1. Case 3 Shows (A) Bilateral and (B) Left Leukocoria. Case 4 Shows (C) Left and (D) Bilateral Leukocoria (note the near Fixation). In Both Cases, Leukocoria Is Evident in the Adducting Eye(s).
All cases were seen in the ophthalmology department for detailed eye examination and refraction. All were found to be orthophoric with no significant refractive errors. This excluded the Bruckner reflex as a possible explanation for the phenomenon, although the Bruckner reflex really describes differences in the quality of the red reflex in coaxial illumination.1 No intraocular cause for the leukocoria could be identified. Furthermore, coaxial red reflex examination could not reproduce the leukocoria.
A literature search revealed one article by Marshall and Gole documenting the phenomenon of leukocoria in three cases of off-axis flash photography.2 They postulated that the source of the white pupil was light reflection from the optic disc. Because the optic disc is situated 15° nasal to the macula, it would be illuminated by a light source 15° temporal to the line of fixation (Fig. 2A). This hypothesis explains all of our cases of unilateral leukocoria because in each case the photographer was positioned temporal to the line of fixation of the eye with leukocoria. It also explains our bilateral case because convergence of the eyes could result in a single central light source (ie, the camera) being 15° temporal to the line of fixation of both eyes (Fig. 2B).
Figure 2. (A) The Right Eye of an Adult Demonstrating Illumination of the Optic Disc when There Is an Angle of 15° Between Fixation and Flash Illumination. (B) Convergence for near Fixation Allows Illumination of Both Optic Discs by the Camera Flash. With an Interpalpebral Distance of 54 mm, This Could Be Seen with a Fixation Target at 9.8 cm and the Camera at 3.83 cm. (C) Using a Camera Placed 120 cm from the Subject’s Face and a Fixation Target Placed at Variable Distances to the Right of the Camera Flash, (i) No Leukocoria Is Produced with the Target at 28 cm (corresponding to an Angle of Approximately 13°), (ii) Right Leukocoria Is Produced with the Target at 32 cm (corresponding to an Angle of Approximately 15°), and (iii) No Leukocoria Is Produced with the Target at 36 cm (corresponding to an Angle of Approximately 17°).
Marshall and Gole based this hypothesis on the approximate angle of fixation as estimated from the photographs, but did not reproduce or verify this hypothesis. We therefore set out to determine whether we could reproduce unilateral leukocoria. In a semi-darkened room, a camera was placed 120 cm from the subject’s face and a fixation target placed at variable distances to the right or left of the camera flash, perpendicular to the line of flash illumination. Recruiting an adult with a pharmacologically dilated pupil to simulate the larger-sized pupil of children, it was found that leukocoria could be produced through an off-axis fixation range of approximately 14° to 16° horizontally, but not at any other angle (Fig. 2C).
We have demonstrated that a marked artefact leukocoria can be reliably produced in low illumination with the subject fixating on a target 14° to 16° to either side of the camera flash, due to reflection of the flash from the optic disc. Only an approximate angle of 15° is required, indicating that provided at least part of the optic disc is on-axis to the camera flash, the effect is produced, albeit to varying degrees. This supports the hypothesis that the optic disc is acting as a reflective surface.2
It is likely that the reason we are seeing a significant number of cases of this type of leukocoria in children is due to the ease of digital photography. It is difficult to gain children’s attention for photographs, so an assistant standing to the side of the photographer is often required to capture and hold attention. Off-axis photographs are therefore more commonly taken in children compared to adults, who usually oblige the photographer by looking at the camera. With digital photography, multiple shots are often taken to capture the “perfect” shot. Together with the larger-sized pupil of the child, these factors greatly increase the chances of flash photography inducing leukocoria in children.
It is therefore important to appreciate this phenomenon as a common cause of unilateral and, less commonly, bilateral artefact leukocoria. However, due to the significance of the differential diagnosis, prompt ophthalmology referral and detailed examination is still warranted.
- Tongue AC, Cibis GW. Bruckner test. Ophthalmology. 1981;88:1041–1044.
- Marshall J, Gole G. Unilateral leukocoria in off axis flash photographs of normal eyes. Am J Ophthalmol. 2003;135:709–711. doi:10.1016/S0002-9394(02)02079-2 [CrossRef]
Summary of Cases of Leukocoria
|Case||Sex||Age at Presentation||Eye With Leukocoria|
|2||F||2 years||Left in 2 separate photographs, taken 1 year apart|
|3||F||5 years||Right and left in separate photographs taken on same day (Figs. 1A and 1B)|
|4||M||6 months||Left and bilateral taken 2 weeks apart (Figs. 1C and 1D)|