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Cas Clinique du Kératoglobe associé à une ectasie prosgressive et Lenticône postérieur: Une évaluation multimodulaire

 To report a rare case of keratoglobus associated with posterior lenticonus and complicated by progressive central ectasia. The patient was examined with a multimodal approach consisting of Corneal Topography and Tomography, Anterior Segment Ocular Coherence Tomography, Specular Microscopy and biomechanical properties evaluation.

The clinical history of a single keratoglobus patient is reviewed during a 5 years period. The patient was referred to us at the age of 5 with a known history of low vision (05/10 cc OU), in the context of high myopia and astigmatism. 

 The clinical diagnosis of keratoglobus was confirmed by topographic, tomographic, pachymetric and AS OCT evaluation. Thorough search for a possible connective tissue disorder was negative. Interestingly, the patient presented a bilateral posterior lenticonus, a finding that is not generally connected to plain keratoglobus cases. During the end of this 5 year observation period, a bilateral gradual central ectasia occured. This was documented by consecutive tomographies (Pentacam HR, Oculus GmbH, Wetzlar, Germany) which also highlighted a gradual increase of the densitometric properties in all zones and layers of the cornea. Epithelial maps were altered and biomechanical properties were severely affected. 

 Keratoglobus is a rare condition usually grouped among other non-inflammatory ectasias, like Keratoconus and Pellucid Marginal degeneration. The exact pathogenesis remains unclear and relevant literature is rather limited. Furthermore, its treatment is still a predicament, as there is no standard protocol regarding visual reabilitation or maintenance of the corneal structural integrity. Regarding the keratoglobus cornea's structural status, assessment of corneal densitometry can be of significant interest, as it provides objective and quantitative data of the cornea's transparency in all its depth and surface. This has already been demonstrated in patients with keratoconus and Pellucid Marginal Degeneration. In such cases, the structural changes that occur lead to increased densitometric values.  In our patient, the Pentacam densitometry evaluation revealed gradually and significantly increasing values not only in the central prodruding area, but also in the peripheral zones of the cornea.

To the best of our knowledge, this is the first report of a keratoglobus patient presenting with posterior lenticonus and evaluated through the corneal densitometry prism.