amblyopic eyes of patients with recovered amblyopia an implication on the future treatment targeting the site(s) Dovepress (P = 0.482). Discussion In this study, we did not observe any significant difference in RNFLT between the affected and fellow eyes neither in patients with recovered amblyopia nor in those with persis- tent amblyopia. Our findings are in agreement with most of the previous OCT studies of amblyopia.17–22 Also, our OCT measurements of the RNFLT in amblyopic eyes, around 100 µm, are generally in line with values published in previ- ous reports of children.12–14,22 On the other hand, Yen et al23 reported that the RNFLT values of amblyopic eyes were significantly thicker than those of the fellow eyes in anisome- tropic amblyopia, but not in strabismic amblyopia. Similarly, Yoon et al24 have shown a significantly thicker RNFLT in hyperopic anisometropic amblyopia. Kee et al18 demonstrated that, although there was no difference in RNFLT between amblyopic and fellow eyes, the RNFLTs of amblyopic eyes were significantly thicker in anisometropic amblyopia than in strabismic amblyopia. Axial length and refractive error have been shown to affect the measurements of RNFLT by OCT.13 It has been demonstrated that RNFLT is positively correlated with refractive error, ie, RNFLT is thicker in more hyperopic eyes.12 In this study, because the affected eyes were signifi- cantly more hyperopic than the fellow eyes in patients with recovered amblyopia and in those with persistent amblyopia, we might have overestimated the RNFLT in the affected eyes or underestimated that in the fellow eyes. The effects of refraction may, in part, explain our results that the RNFLT was slightly thicker for the affected eyes than for the fel- low eyes in patients with recovered amblyopia and in those with persistent amblyopia. Nevertheless, logistic regression analysis showed that the association between RNFLT and the persistence of amblyopia remained insignificant after adjusting for refraction as a potential confounder. In addi- tion, the change in RNFLT associated with refraction is quite small; the RNFLT only increased by approximately 1.671 µm for each diopter of hyperopia.12 Although his- tological and functional changes in the LGN and visual cortex have been well established, the difference in RNFLT found between the amblyopic and fellow eyes is fairly small, even when there is a statistically significant difference.23,24 Therefore, the amblyopic process does not seem to have a profound effect on the retina. Our finding will not change the current practice of amblyopia treatment, but it may have Clinical Ophthalmology 2010:4 Retinal nerve fiber layer thickness in amblyopia affected by amblyopia. Disclosure The authors report no conflicts of interest in this work. References 1. von Noorden GK. Amblyopia: a multidisciplinary approach. Proctor lecture. Invest Ophthalmol Vis Sci. 1985;26(12):1704–1716. 2. Campos E. Amblyopia. Surv Ophthalmol. 1995;40(1):23–39. 3. Miki A, Liu GT, Goldsmith ZG, Liu C-SJ, Haselgrove JC. Decreased activation of the lateral geniculate nucleus in a patient with anisome- tropic amblyopia demonstrated by functional magnetic resonance imaging. Ophthalmologica. 2003;217(5):365–369. 4. Hess RF, Thompson B, Gole G, Mullen KT. Deficient responses from the lateral geniculate nucleus in humans with amblyopia. Eur J Neurosci. 2009;29(5):1064–1070. 5. Ikeda H, Tremain KE. Amblyopia occurs in retinal ganglion cells in cats reared with convergent squint without alternating fixation. Exp Brain Res. 1979;35(3):559–582. 6. Hess RF. Amblyopia: site unseen. Clin Exp Optom. 2001;84(6): 321–336. 7. Lempert P. Optic nerve hypoplasia and small eyes in presumed amblyopia. J AAPOS. 2000;4(5):258–266. 8. Lempert P. The axial length/disc area ratio in anisometropic hyperopic amblyopia: a hypothesis for decreased unilateral vision associ- ated with hyperopic anisometropia. Ophthalmology. 2004;111(2): 304–308. 9. Lempert P. Retinal area and optic disc rim area in amblyopic, fellow, and normal hyperopic eyes: a hypothesis for decreased acuity in amblyopia. Ophthalmology. 2008;115(12):2259–2261. 10. Medeiros FA, Zangwill LM, Bowd C, Weinreb RN. Comparison of the GDx VCC scanning laser polarimeter, HRT II confocal scanning laser ophthalmoscope, and stratus OCT optical coherence tomo- graph for the detection of glaucoma. Arch Ophthalmol. 2004;122(6): 827–837. 11. Parisi V, Manni G, Gandolfi SA, Centofanti M, Colacino G, Bucci MG. Visual function correlates with nerve fiber layer thickness in eyes affected by ocular hypertension. Invest Ophthalmol Vis Sci. 1999;40(8): 1828–1833. 12. Salchow DJ, Oleynikov YS, Chiang MF, et al. Retinal nerve fiber layer thickness in normal children measured with optical coherence tomog- raphy. Ophthalmology. 2006;113(5):786–791. 13. Huynh SC, Wang XY, Rochtchina E, Mitchell P. Peripapillary retinal nerve fiber layer thickness in a population of 6-year-old children: findings by optical coherence tomography. Ophthalmology. 2006;113(9):1583–1592. 14. El-Dairi MA, Asrani SG, Enyedi LB, Freedman SF. Optical coher- ence tomography in the eyes of normal children. Arch Ophthalmol. 2009;127(1):50–58. 15. Wang XY, Huynh SC, Burlutsky G, Ip J, Stapleton F, Mitchell P. Reproducibility of and effect of magnification on optical coher- ence tomography measurements in children. Am J Ophthalmol. 2007;143(3):484–488. 16. Huynh SC, Wang XY, Burlutsky G, Mitchell P. Symmetry of optical coherence tomography retinal measurements in young children. Am J Ophthalmol. 2007;143(3):518–520. 17. Atilla H, Batiog˘lu F, Erkam N. Retinal nerve fiber analysis in subjects with hyperopia and anisometropic amblyopia. Binocul Vis Strabismus Q. 2005;20(1):33–37. 18. Kee SY, Lee SY, LeeYC. Thicknesses of the fovea and retinal nerve fiber layer in amblyopic and normal eyes in children. Korean J Ophthalmol. 2006;20(3):177–181. submit your manuscript | www.dovepress.com Dovepress 1063