Ocular histopathology of myotonic dystrophy. A clinicopathologic case report

Clinical Case Notes. Recurrent posterior capsular opacification and capsulorhexis contracture after cataract surgery in myotonic dystrophy

Cataracts are well known to be associated with myotonic dystrophy. Less well known are the phenomena of recurrent posterior capsule opacification and capsulorhexis contracture post cataract surgery. Two cases are described herein of postoperative capsular complications requiring multiple capsulotomies in patients with myotonic dystrophy. It is proposed that a common aetiology may underlie both posterior capsule opacification and capsulorhexis contracture in myotonic dystrophy cases.

[Severe bilateral capsulorhexis contraction after cataract surgery in myotonic dystrophy: a case report]

INTRODUCTION

The Authors report the case of a 50-Year-old man with myotonic dystrophy, who developed severe bilateral capsulorhexis contracture after uneventful cataract surgery.

OBSERVATION

Phacoemulsification was performed in both eyes with implantation of intraocular lenses. The patient came to complain of decreased vision in both eyes (4/10 Parinaud 4). Visual acuity initially improved after surgery to 8/10 P2 in each eye. After 7 months for the right eye and 3 Months for the left eye, the patient presented with dramatically reduced vision, caused by a severe capsulorhexis contracture. Anterior capsulotomies with the Nd:YAG laser were performed in both eyes to treat this complication. It was sufficient on the left eye but the right eye required a surgical anterior capsulectomy to remove the IOL and the bag and put in an Artisan lens.

DISCUSSION

Capsulorhexis contracture results from fibrous metaplasia of lens epithelial cells from the anterior capsule. Myotonic dystrophy appears to predispose to the development of severe capsulorhexis contracture after phacoemulsification.

Recurrence of secondary opacification and development of a dense posterior vitreous membrane in patients with myotonic dystrophy

We present 3 patients diagnosed with myotonic dystrophy who developed recurrences of secondary opacification. One developed a dense posterior vitreous membrane. Patients with myotonic dystrophy may have an increased risk for recurrent secondary opacification and for developing intraocular fibrosis after cataract extraction.

Severe capsulorhexis contracture after cataract surgery in myotonic dystrophy

A 42-year-old woman with myotonic dystrophy developed bilateral severe capsulorhexis contracture after uneventful phacoemulsification cataract surgery with implantation of 1-piece poly(methyl methacrylate) intraocular lenses (IOLs). The anterior capsular opening in her right eye constricted to a diameter of 0.7 mm, reducing visual acuity to counting fingers. Complete closure of the capsulorhexis with IOL encapsulation developed in her left eye, reducing visual acuity to hand movements. Surgical anterior capsulectomies restored visual acuity to 6/9 in both eyes. Myotonic dystrophy may predispose to the development of severe capsulorhexis contracture after cataract surgery.

Eye movement abnormalities in myotonic dystrophy

We studied saccade and smooth pursuit eye movements in 31 patients suffering from myotonic dystrophy (MD). On the basis of mean value comparisons, saccades were slower and hypometric and smooth pursuit eye movements performed worse in MD patients than in controls. On an individual basis, saccade duration was prolonged in 67.7%, saccades were hypometric in 19.4%, saccade latency was delayed in 9.7%, and the smooth pursuit performance index was decreased in 9.7% of patients. Eye movement abnormalities did not correlate with those detectable by visual, brain-stem auditory and somatosensory evoked potentials. We attempted to classify eye movement abnormalities as myogenic or neurogenic on the basis of differences in combination of eye movement abnormalities and the occurrence of D5/D35 dissociation; the latter consists of a prolonged duration for large (35 degrees) but not for small (5 degrees) saccades. Since D5/D35 dissociation occurred in 26/33 multiple sclerosis patients with increased saccade duration, we considered it to be a neurogenic pattern attributable to a central nervous system (CNS) dysfunction. A prolonged duration without dissociation especially in combination with saccade hypometria, is interpreted as a myogenic pattern, although the lack of dissociation may also occur with CNS impairment in case of a marked increase in saccade duration. Accordingly we classified the oculomotor abnormalities detected as neurogenic in 11 MD patients and as myogenic in another 10, but in some subjects belonging to the second group concomitant CNS impairment is not to be excluded.

Foveal photopigment kinetics--abnormality: an early sign in myotonic dystrophy?

Twelve subjects with minimal expression of the myotonic dystrophy (MyD) gene were investigated by retinal densitometry, a technique which has been used to study the properties of photopigments in the living eye and to detect photoreceptor abnormalities. Other investigations included slit-lamp examination, funduscopy, raleigh matches with the anomaloscope, tonometry, and neurological examination, including electroretinography (ERG) and pattern visual evoked potentials recording. Foveal densitometry demonstrated reduced values of the macular photopigment density difference with normal photopigment kinetics in early phases of the disease, even in asymptomatic individuals. The densitometric values correlated with decreased amplitudes of the photopic ERG a-wave. These findings may be explained by loss or dysfunction of the outer segments of foveal receptors. It is yet unknown whether or not these changes are secondary to other observed neuroretinal abnormalities in MyD. The most likely explanation might be an abnormality of the Na, Ca:K exchanger at the level of the outer segments of the photoreceptors whether or not in combination with a dysfunction of voltage generation systems, involving both photoreceptors and retinal pigment epithelium.

Retinal changes in myotonic dystrophy: a clinicomorphological study

This report appears to be the first ultrastructural study of the maculopathy and peripheral pigmentary retinopathy in myotonic dystrophy. Nine eyes from five patients observed during life are described. The findings were similar in all eyes, the retinal pigment epithelium in the macular region containing an accumulation of lipofuscin in large hyperpigmented cells. Pigment-laden profiles found in the subpigment epithelial space or subretinal space were interpreted as an attempt to discharge the pigment. Stress fibres of actin microfilaments were thrown into prominence by the irregularity of the pigment epithelium. In the periphery migration of retinal pigment cells into the retina occasionally resulted in the formation of bone corpuscles around occluded vessels, as occurs in retinitis pigmentosa; but more often the clumps were coarser and surrounded basement membrane material. Central and peripheral epiretinal membranes were also observed.

Myotonic muscular dystrophy associated with ritodrine tocolysis

A patient thought to be normal was admitted with premature labor at 29+ weeks' gestation. Treatment with the beta-mimetic ritodrine hydrochloride appeared to provoke symptoms of myotonic muscular dystrophy. Neurological history and examination confirmed the presence of previously unsuspected myotonic dystrophy in the patient, her father, and paternal grandfather. Discontinuation of the drug led to improvement in myotonia symptoms but worsening premature labor. Magnesium sulfate did not provoke the same symptoms but was unsuccessful in controlling premature contractions. Long-term management with bed rest, phenytoin, and isoxsuprine hydrochloride resulted in term delivery. Subsequently, maternal symptoms of myotonia disappeared. Congenital myotonia was suspected in the fetus because of the ultrasonic demonstration of polyhydramnios and reduced fetal movements. This was confirmed at delivery. The mechanism by which ritodrine unmasked the myotonia is unclear but may be related to changes in the cell membrane (chloride conductance, the sodium-potassium pump, or membrane polarization).

Fluoro-photometry in myotonic dystrophy

We found pigment alterations in the anterior segments of the eyes of patients with myotonic dystrophy. We therefore performed fluoro-photometry in a group of ten myotonic patients and the results were compared with those of a group of normal persons. The fluorescence levels in the aqueous and vitreous of the myotonic eyes appeared to be two or three times higher than in the normal eyes. This brings us to the conclusion that myotonic eyes have a defect in the blood-ocular barriers.

Myotonic dystrophy as a disease of abnormal membrane receptors: an hypothesis of pathophysiology and a new approach to treatment

Muscle weakness, clinical myotonia, and multiple systemic organ disturbances characterize myotonic dystrophy. Many of these systemic disturbances involve target organ insensitivity to aminergic or peptidergic (hormonal) stimulation. Reduced density or impaired function of aminergic and peptidergic (hormonal) receptors throughout the body may underlie this disorder. Tricyclic antidepressant augmentation of aminergic function ameliorates depressive symptoms, increases strength, and improves clinical myotonia in myotonic dystrophy patients.