As demonstrated in transgenic mice models FGF-3 plays a role in corneal development and epithelial differentiation 6
. Immunoreactive FGRF3 was found throughout the cornea, and intense positivity was seen in the corneal epithelium, endothelium, Descemets membrane, and fibroblasts of the substantia propria 7
. FGFR3 is upregulated in skin wounds and in migrating neural crest cells during development 8
. Therefore, FGF-3 and FGFR3 might participate in corneal healing and cell migration. Hence, their maldistribution in corneal tissue might cause unexpected changes on ophthalmological practice. As increased signal transduction from a mutated FGFR3 causes an abnormality of cartilage formation in achondroplasia, the same mutation might lead to abnormality in corneal parameters such as CCT, CH and CRF.
The Pentacam Scheimpflug is a relatively new, non-contact optical system, specifically designed to image the anterior segment of the eye. It is an easy-to-use anterior segment analyser, and its high reliability and repeatability, have been documented 9.
ORA is a new non-contact tonometer developed by Reichert, that measures IOP and new metrics, CH and CRF. It uses a metered collimated air pulse to applanate the cornea and an infrared electro-optical system to record inward and outward applanation events. The air pulse deforms the cornea through an initial applanation event, then beyond into concavity, and gradually subsides, allowing the cornea to rebound through a second applanation. This dynamic assessment of corneal biomechanical properties provides metrics of both the corneas viscous and elastic qualities as CH and CRF, respectively 5. Many studies showed that ORA values - especially CH vary, some subjects with diseases have normal CH measurements whereas some normal subjects have abnormal CH values. This overlap of CH values presents major challenges when using ORA as a diagnostic tool 5,10. However, CH and CRF are accepted as pressure-independent risk factors for glaucoma 10. Lower the CH value higher the risk for glaucoma is.
Among the 4 achondroplasia patients CCT was over normal limits in both eyes of one patient, and CH and CRF was lower in three eyes of two patients with accompanying high IOP readings. Although we did not detect any glaucomatous damage in our suspected cases, these results might suggest that in achondroplasia the affection of FGFR3 could be related to a more prone situation for glaucoma formation. The lack of any glaucomatous damage in our suspected cases might be related to the young age of the patients. Further studies with larger number of achondroplasia patients are needed to demonstrate the effects of achondroplasia in cornea and corneal biomechanics.