A Subtle Unrecognized Ectopia Lentis With A Large Angle Kappa Perceived And Managed As Keratoconus; A Case Report

Ectopia lentis et pupillae is a rare autosomal recessive congenital disorder characterized by the displacement of both the lens and pupil in opposite direction, typically confined to ocular involvement with no systemic associations. Refractive error in the form of astigmatism is a possible way of presentation. In presence of large angle kappa, the condition may present diagnostic challenges due to similar tomographic features with other ocular disorders, such as keratoconus. Misdiagnosis is possible, especially when lenticular and corneal astigmatism are both present, complicating the clinical picture. Herein we report a case of ectopia lentis previously misdiagnosed and managed as keratoconus.

Case report

We report a 22-year-old girl who presented to our clinic for a routine checkup. She was previously diagnosed with keratoconus and managed with crosslinking (CXL) in the left eye as per her report. She was medically free with a negative surgical history other than CXL. Upon examination in our clinic, her best corrected spectacle visual acuity was 20/20 in the right eye and 20/30 in the left eye. The corneal tomography showed a posterior elevation in the left eye, yet she had a large angle kappa. No other signs of keratoconus was there and all tomographic scans confirmed stability. She had discrepancy between the astigmatism shown by tomography (3.00 diopters) and refraction (-5.25) suggesting a possible combination of both corneal and lenticular astigmatisms. On subsequent examination, despite the poor pupil response to mydriatics, slit lamp exam revealed slightly inferonasally displaced pupils and mild superotemporal lens subluxation which was confirmed with ultrasound biomicroscopy. Ultimately, all these finding favored the diagnosis of ectopia lentis et pupillae for which genetic workup was carried out after obtaining the patient written consent (pending results).

This case demonstrates the diagnostic complexity of ectopia lentis et pupillae especially when it is subtle and mimics more common conditions such as keratoconus as in this case. Proper evaluation and a thorough differential diagnoses are essential in such cases to ensure an accurate diagnosis. Early detection is crucial for timely intervention, helping to prevent/manage potential complications such as cataracts, glaucoma, and retinal detachment.