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Editor,—Keratoconus is very rarely found in patients with congenital rubella syndrome (CRS). The only known aetiology of keratoconus associated with CRS is eye rubbing.1 We report here a patient with CRS who developed idiopathic keratoconus.
CASE REPORT
A 24 year old woman with CRS was examined for progressive visual blurring of 2 years’ duration in her left eye. The diagnosis of CRS was based on the maternal history of rash and fever in the first trimester of pregnancy, cataract, and microphthalmia in the right eye, bilateral rubella retinopathy, nystagmus, deafness, congenital heart disease.
Available medical records dated from the time she was 1 year old. At that time, extracapsular cataract surgery was performed in the right eye. She had esotropia in the right eye and poor fixation. Apart from pigmentary changes in the fundus, the left eye was normal. A follow up examination when she was 15 documented nystagmus, esotropia, and microphthalmia in her right eye, and bilateral rubella retinopathy. Visual acuity was RE light perception; LE 6/9 (with −4.0 −1.0 c × 180). Two other examinations at the ages of 18 and 21 gave similar results.
On present examination, visual acuity with spectacles was LE 6/60. Retinoscopy revealed high, irregular myopic astigmatism with scissoring of the red reflex. Central keratometry showed irregular mires which could not be superimposed; 4 dioptre irregular astigmatism was found. A conical reflection on the nasal cornea was obtained by shining a penlight from the temporal side (Rizzuti’s sign). Bulging of the lower eyelid on downgaze was also observed (Munson’s sign). Slit lamp examination revealed an inferiorly located ectatic protrusion of the central cornea with reticular anterior stromal scars. As a result, the diagnosis of mild keratoconus was made. Treatment with a Softperm contact lens was successful and visual acuity was again LE 6/9. All other ocular findings were the same as in earlier observations.
The patient attended a special school for the deaf and dumb, learning sign language and to read and write. There was no history of eye rubbing or atopy, or a family history of keratoconus. Serum total IgE (34 IU/ml) and blood eosinophils (1.1%) were normal.
COMMENT
Congenital rubella produces a spectrum of ocular and systemic abnormalities. Infection during the first trimester of pregnancy is more serious, with the virus disrupting organogenesis and differentiation. Many fetal tissues are susceptible to infection leading to the abnormalities found in the CRS—deafness, cardiac malformations, bone and dental abnormalities, ocular malformations, and mental retardation.
“Salt and pepper” retinopathy is the most common ocular disorder; other ocular manifestations include microphthalmia, strabismus, congenital cataract, transient corneal leucoma, iris atrophy and hypoplasia, and glaucoma.2 Keratoconus and hydrops have been reported in patients with CRS with a history of mental retardation and eye rubbing.1
The microtrauma associated with eye rubbing is generally thought to be the aetiological link between keratoconus and associated systemic and ocular diseases.3-5 All four patients with keratoconus and CRS described by Boger et al 1 were retarded and vigorously rubbed and poked their eyes. These authors postulated that keratoconus and acute corneal hydrops probably resulted from chronic traumatising mannerisms common in other mentally retarded patients5 and is not specific to congenital rubella. Thus far, this is the only known aetiology of keratoconus associated with CRS.
In the case presented here the keratoconus appeared to be idiopathic. Indeed, there was no history of eye rubbing or atopy, or family history of keratoconus. To the best of our knowledge, this report is unique in as far as idiopathic keratoconus has never been associated with CRS. It is likely that in this case there is no such association but merely an overlap of two uncommon conditions6 7 occurring in the same person. An association between idiopathic keratoconus and CRS may be determined only after other confirmatory cases have been reported in the literature.