[Fundus features of nanophthalmos analyzed by optical coherence tomography].

OBJECTIVE

To observe the fundus features of nanophthalmos with or without secondary glaucoma using spectral domain optical coherence tomography (SD-OCT).

METHODS

It was a retrospective case-series study. Twenty-three eyes of 12 patients (6 female, 6 male) who were clinically identified to be nanophthalmos (axial length ≤ 20.0 mm) in Zhongshan Ophthalmic Center from June 2008 to December 2010 and twenty-three eyes of 23 age and sex matched normal controls were included in this study. All patients underwent ophthalmological examinations including best-corrected visual acuity, refraction, slit-lamp biomicroscopy and fundus examination, Goldmann applanation tonometry, A-scan and B-scan ultrasound examinations, ultrasound biomicroscopy, fundus photography and spectral domain optical coherence tomography (SD-OCT). All examinations were carried out with natural pupil. The fundus features detected by OCT were compared between nanophthalmos and normal controls, and among nanophthalmos with or without secondary glaucoma.Independent-samples t test was used to analyze the difference of retinal thickness between nanophthalmoic eyes and controls and also between nanophthalmoic eyes with and without secondary glaucoma. Pearson correlation analysis was used to analyze the correlation between axial length and macular retinal thickness.

RESULTS

The average age of 12 patients was (25.0 ± 13.1) years, and the mean axial length was (17.30 ± 1.66) mm. Thirteen eyes suffered from secondary glaucoma because of angle closure with average intraocular pressure (IOP) of (28.62 ± 9.18) mm Hg (1 mm Hg = 0.133 kPa). The average IOP of the other 10 eyes without secondary glaucoma was (14.96 ± 3.21) mm Hg.OCT images revealed thickening of the retina in macular fovea, with residual retinal nerve fiber layer, ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer, and broadened outer nuclear layer in 23 eyes with nanophthalmos. Pre-retinal folds were seen in 5 eyes with macular cysts.Shallow serous retinal detachment was found in 3 eyes, 2 of which showed focal thickening of retinal pigment epithelium as leopard spots. The cup were not obvious and retina around optic nerve head was thickened in 10 eyes without secondary glaucoma and 4 eyes with secondary early glaucoma, which seemed to be pseudopapilloedema. The other 9 eyes with secondary late glaucoma revealed enlarged cup . The mean macular foveal thickness of nanophthalmic eyes[ (335.65 ± 91.45) µm] was significantly thickened than normal control group [(192.72 ± 11.18) µm] (t = 10.50, P = 0.000) . The mean macular foveal thickness of nanophthalmos with glaucoma [(323.70 ± 104.09) µm] was thinner than those without glaucoma [(403.50 ± 130.24) µm] (t = 3.50, P = 0.002). Macular foveal thickness were negatively related with axial length in both nanophthalmos with and without secondary glaucoma (R = -0.797, P = 0.001).

CONCLUSIONS

Macular hypoplasia and crowded optic nerve head are two important characteristic of fundus appearances in nanophthamos.SD-OCT can clearly reveal the changes of macular retina and optic nerve head. SD-OCT will be a very useful tool to help diagnose nanophthamos and evaluate its possible complications.