Sir,

Alport’s syndrome is a rare basement membrane disorder characterized by progressive hereditary nephritis, sensorineural hearing loss and ocular abnormalities. The inheritance is predominantly X-linked (85%), although it can be autosomal recessive (10%) or autosomal dominant (5%).1 Homozygote males are usually severely affected but females tend to have a mild form, often with only microscopic haematuria and normal renal function.1 The ocular abnormalities in the X-linked form are characteristically a dot-and-fleck retinopathy, less often anterior lenticonus and rarely a posterior polymorphous corneal dystrophy.1,2 Additional ocular abnormalities are not uncommon, including cataracts, posterior lenticonus and retinal detachment.2

This case report of a female patient has several unusual features. There was no positive family history, renal function was severely affected and prior to developing visual symptoms, the cause of renal failure was unclear. In addition the ocular features included a unilateral dot-and-fleck maculopathy and bilateral anterior lenticonus, known to occur in approximately 85% and 25% of affected males respectively, but both rarely reported in females with the syndrome.1

Case report

A 40-year-old lady was referred by her optometrist with bilateral visual failure and a large myopic shift over a 2-week period. Within this period her refractive status had changed from −7.75DS / −1.25DC × 105 right eye, −6.75DS left eye, to −10.00DS / −1.75DC × 115 right eye, −8.25DS / −0.50DC × 30 left eye.

The patient had no significant past ocular history other than wearing spectacles to correct myopia for many years. Her past medical history however, included bilateral hearing loss for which she wore hearing aids and a previous renal transplant (1994) for renal failure secondary to a ‘nephritis’ of unknown aetiology. She was on long-term immunosuppressive therapy, including oral steroids. There was no family history of ocular or systemic conditions.

On examination the Snellen visual acuity with spectacles was 6/60 right eye and 6/24 left eye. The ocular surface and corneas were normal, with intraocular pressures of 12 mmHg in each eye. There was marked bilateral anterior lenticonus (Figure 1), with a positive ‘oil droplet’ sign on retinoscopy. Both lenses were clear, with no evidence of cataract. Fundoscopy revealed subtle pale perifoveal flecks at the right posterior pole, but no abnormalities in the left eye.

Figure 1
figure 1

Anterior lenticonus in a 40-year-old patient with Alport’s syndrome.

Full size image

The ocular signs in conjunction with her hearing loss and renal disease were compatible with a clinical diagnosis of Alport’s syndrome. The visual failure appeared to be due to the development or exacerbation of bilateral anterior lenticonus. A right clear lens phacoemulsification and intraocular lens (IOL) implantation was performed under general anaesthetic. The implant used was a foldable, hydrophobic, acrylic IOL. The right eye was 6/9 unaided (6/5 with pinhole) the following day. The postoperative period was uneventful, although topical steroids were required at a slightly increased frequency for anterior uveitis. The left eye underwent a similar procedure 8 weeks later, the unaided vision settling at 6/12, improving to 6/6 with a small myopic correction.

A review, 12 months postoperatively, disclosed the following findings on examination. The best-corrected Snellen visual acuity had remained 6/6, in each eye, with a small myopic correction. The anterior chambers were quiet, the IOL implants were well-centred and the intraocular pressures were normal. No significant posterior capsular opacification was present. The perifoveal flecks at the right posterior pole were unchanged.

Comment

Alport’s syndrome was first described as an acute haemorrhagic nephropathy with deafness in 1927, the association with anterior lenticonus being recognized later.3,4 The underlying abnormality is a defective type IV collagen, the synthesis of which is coded for on the X chromosome. Histopathological features of anterior lenticonus include marked thinning of the anterior capsule centrally, decreased number of lens epithelial cells which may also be atypically arranged and large numbers of partial capsular dehiscences containing fibrillar material and vacuoles.5,6,7,8

The association of ‘capsular fragility’ with anterior lenticonus secondary to Alport’s syndrome is well documented6,7,8 and is supported by rare reports of spontaneous rupture of the capsule.9,10 In our case, however, we found that the anterior capsule was highly elastic, making the capsulorhexis technically more difficult in both eyes. The capsule elasticity was far greater than one would expect in relation to the patient’s age. John et al have also reported a case where the anterior capsules were ‘tough’.11 It is possible that fragile capsules represent a more severe form of ocular disease.

There are various precautions that can be taken to help complete a successful capsulorhexis in anterior lenticonus. It is worth considering a general anaesthetic in challenging cases, as the procedure may take longer and akinesia is more important. Making a small paracentesis initially allows for a complete aqueous-viscoelastic exchange in a ‘sealed’ anterior chamber. Use of a high molecular weight viscoelastic agent may further help deepen the anterior chamber and flatten the anterior capsule. We found it necessary to perforate the capsule with a 27G needle and then complete the capsulorhexis using microforceps. The capsule was highly elastic and far more prone to tear out towards the lens periphery.

Having completed the capsulorhexis a gentle, but thorough, hydrodissection from several sites was made to ensure that the lens rotated well within the capsular bag. This is particularly important in younger patients when the lens can be extremely soft. Extreme caution is required when there are associated posterior subcapsular opacities or posterior lenticonus, since hydrodissection could result in a posterior capsular rupture. Under these circumstances good hydrodelineation to ensure easy nucleus rotation within the epinuclear shell is recommended. A standard ‘bowl technique’ was used during the phacoemulsification, the centre of the soft lens being debaulked and then imploded with high vacuum during the second stage of nucleus removal. The lens cortex was aspirated in a circumferential fashion in order to avoid unnecessary tension on the zonules. The capsule was polished thoroughly to avoid capsule phimosis and possible posterior capsule opacification and a foldable, hydrophobic, acrylic IOL was inserted into the capsular bag.

Clear lens phacoemulsification is an excellent surgical procedure for the treatment of anterior lenticonus in patients with Alport’s syndrome, allowing for rapid visual rehabilitation.