Abstract
Abstract: :
Purpose:Nystagmus associated with retinal disease such as achromatopsia and congenital stationary night blindness is usually detected and diagnosed in infancy. We describe three patients with retinal dystrophy who developed nystagmus. Methods:Three females with poor vision since childhood developed further deterioration in vision later in life. We carried out eye movement recordings using an infrared eye tracker (Eye Link, Sensorimotor Instruments, Germany) and performed a detailed clinical assessment in all cases. Results:All three patients were female. The causes of poor vision were retinal dystrophy (Senior–Loken syndrome), Bardet–Biedl syndrome and rod–cone dystrophy. All patients had annual ophthalmological examinations with normal ocular motility and developed nystagmus aged fourty eight, sixteen and twelve respectively. The patient with Senior–Loken syndrome had visual acuity deteriorating from 20/60 to 20/120 over twelve months. In the Bardet–Biedl patient, visual acuity deteriorated from 20/60 to 20/180. The patient with rod–cone dystrophy had gradual deterioration in visual acuity from 20/60 to 20/600 over nine years. Eye movement recordings in the patient with Senior Loken syndrome showed a rotatory nystagmus worse on upgaze and horizontal versions. The second patient with Bardet–Biedl syndrome had a conjugate, rotatory nystagmus. The patient with rod–cone dystrophy had a conjugate pendular nystagmus with a torsional component. Interestingly, the patient with Senior–Loken syndrome noticed an improvement in vision with eye movement recordings confirming a reduction in amplitude of nystagmus on treatment with gabapentin. Conclusion:To the best of our knowledge, this is the first description of nystagmus in cases of retinal dystrophy emerging later in life. Since most individuals do not develop nystagmus simply due to deterioration in vision, we postulate that the retinal dystrophy predisposes the individual to developing nystagmus, and the nystagmus manifests itself when vision worsens.
Keywords: eye movements • neuro–ophthalmology: diagnosis • ocular motor control