Is macular pigment optical density really involved in fixation preference?

PURPOSE

To evaluate macular pigment optical density in healthy children and to compare the values with those of strabismic children with respect to fixation preference.

METHODS

The study recruited 54 healthy and 41 strabismic children. Two groups were matched in terms of gestational age, birth weight, and body mass index. All participants underwent complete ophthalmological evaluation and macular pigment optical density measurement and filled a self-reported food frequency questionnaire. Strabismic children were categorized according to fixation preference.

RESULTS

The mean age was 9.87 ± 2.39 years in healthy children and 9.07 ± 2.07 years in children with strabismus (p = 0.091). Mean macular pigment optical density was 0.23 ± 0.25 in healthy eyes and 0.25 ± 0.27 in non-preferred eyes of strabismic children (p = 0.964). Macular pigment optical density was significantly higher in preferred eyes of strabismic children (0.43 ± 0.34) compared to non-preferred eyes (p = 0.004) and healthy eyes (p = 0.001). There was a difference of macular pigment optical density between both eyes in patients with grades 1, 2, and 3 fixation preference, whereas patients with grade 4 preference had similar macular pigment optical density in both eyes (p = 0.008). There was a statistically significant positive correlation between macular pigment optical density in preferred eyes and body mass index (r = 0.354, p = 0.023).

CONCLUSION

Preferred eyes of children with strabismus seem to have higher macular pigment optical density readings. This difference may emerge from the higher tendency of recognizing the flicker stimulus while preferred eye is under testing. Similar macular pigment optical density in healthy and non-preferred eyes and the fact that both lower than preferred eyes remain unexplained. It should be kept in mind that macular pigment optical density results should be carefully interpreted and macular pigment optical density in cases with strabismus should be further investigated.