Ophthalmological and Orthoptic Findings in Down Syndrome: Is Genotype-Phenotype Correlation Possible?

This is a preliminary study to investigate a feasible genotype-phenotype correlation by defining ophthalmological findings in different genotypes of Down syndrome (DS).

The study included 62 eyes of 31 DS patients. Patients were further subgrouped according to cytogenetic forms of DS. A comprehensive ophthalmological examination was performed and, biometric, keratometric, and pachymetric parameters were evaluated.

The mean best-corrected visual acuity (BCVA) of trisomy 21 was 0.41 ± 0.14 (0.1-0.6) and was 0.6 ± 0.09 (0.5-0.7) for both mosaic and translocation trisomy 21 (p = 0.004). While 6 of the trisomy 21 patients (24%), 2 of the mosaic patients (66.7%), and all of the three translocation type patients had a normal accommodation response, the remaining patients had accommodation lags (p = 0.013).

Lens opacities and fundus abnormalities were more common in trisomy 21 (p < 0.001). The angle kappa was larger in trisomy 21 and smallest in the translocation trisomy 21 (p = 0.014). K₂ and corneal apex curvature were highest in trisomy 21 (p = 0.05 and p = 0.006, respectively). BCVA and accommodation response were reduced whereas lenticular opacities and fundus abnormalities were more common in trisomy 21. In addition, central cornea was steeper and angle kappa was larger. Further studies with larger cohorts would display differences among subgroups of cytogenetic abnormality.