Sir,

In cases of blunt ocular injury, cataract may result from the impact of trauma with or without anterior and/or posterior capsular defect. We report an intralenticular sign to anticipate a pre-existing posterior capsule defect (PPCD) in white mature cataract with an intact anterior capsule following blunt trauma.

Case report

A 17-year-old male presented with the history of trauma to the left eye with a plastic ball 10 days back and progressive dimness of vision since then. He had an accurate projection with normal pupillary reactions. Slit-lamp examination revealed a white mature cataract with intact anterior capsule and a ‘sinking cortex’ sign. Intraocular pressure was normal. Fundus details were not visible. A-Scan examination was un-confirmatory. B-Scan ultrasonography revealed floating vitreous echoes of moderate density just behind the posterior capsule (Figure 1). Right eye examination revealed no abnormality on detailed slit-lamp examination after dilatation of pupils.

Figure 1
figure 1

B-Scan photograph showing vitreous floaters.

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At the time of surgery, on the following day, slit-lamp examination on the operating table also revealed ‘sinking cortex’ sign (Figure 2a). There was no postural difference in the appearance on slit-lamp examination in sitting position as compared to examination on slit lamp mounted on the operating microscope in supine position. Surgery was performed using principles of the close chamber technique under peribulbar anaesthesia as described elsewhere.1 A single piece AcrySof® (AcrySof®; Alcon laboratories, Fort Worth, TX, USA, model SA60AT) IOL was implanted in the sulcus.

Figure 2
figure 2

(a) White arrow indicates the normal cortex. Yellow arrow indicates ‘sinking cortex’ sign, a dimple with a hollow space between the intact anterior capsule and cortex. (b) A postoperative photograph of the same patient with pre-existing posterior capsule defect (PPCD), at 1-month follow-up, showing a small anterior capsulorhexis with AcrySof SA60AT in the ciliary sulcus.

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On first postoperative day the anterior segment was quiet with normal IOP of 20 mmHg. On 1-month follow-up UCVA was 20/30, with quiet anterior segment and a centred IOL (Figure 2b).

Comment

Posterior capsule visualization is difficult in white mature cataracts. Traumatic cataracts are often associated with PPCD.2, 3, 4, 5, 6 In white mature cataracts, B-Scan ultrasonography is a useful tool for indirect documentation of PPCD. PPCD is recognized by floating echoes behind the posterior capsule. An accurate preoperative clinical diagnosis of PPCD in white mature cataracts with intact anterior capsule still remains uncertain.

The hallmark of identifying PPCD in white mature cataracts is by ‘sinking cortex’ sign. As a result of the defect in the posterior capsule, the posterior cortex sinks behind in the vitreous cavity. Moreover, there is always some absorption of the lens matter. All these together will create an empty space in between the intact anterior capsule and the anterior cortex. This empty space appears as a dimple in the anterior cortex of the cataract, which we call ‘sinking cortex’ sign (Figure 2a). A swift total maturation of the cataract, the ‘sinking cortex’ sign, and floating echoes in the B-Scan are a sure indication of PPCD.

Contusion cataract may develop due to contra-coup damage following a blow to the orbital area. Shock waves pass through the eye, possibly rupturing the anterior or posterior lens capsule with subsequent lens opacification. There is an equatorial expansion of the eye that may cause a rupture in the lens capsule.7 The ‘typical’ posterior capsule tears in cases of blunt trauma are usually located in the central part of the posterior capsule, the area thinnest and most vulnerable to concussional insult. The typical appearance described in the literature has thickened and fibrosed margins of these posterior capsule tears, which have been attributed to the migration of the hyperplastic epithelial cells that collect in this region.2 Congenital deformity like posterior lentiglobus was ruled out from the history, detailed slit-lamp evaluation of posterior capsule after dilatation in fellow eye and absence of any amblyopia postoperatively.

An accurate diagnosis helped us in preoperative counselling regarding potential difficulties during surgery. Anticipation of PPCD made us perform a small anterior capsulorhexis contemplating ciliary sulcus fixation of IOL (Figure 2b) and abandoning hydroprocedures. Use of the principles of close chamber technique1 prevented vitreous loss and posterior segment complications. We routinely use single piece AcrySof IOL for sulcus fixation. In our experience, symmetry of the placement of this IOL is critical and not the bulk of the haptic. At the root of the iris the bulk and the square edge of the single piece haptic will not produce excessive irritation, as it is not mobile.

In summary, this case emphasizes the importance of ‘sinking cortex’ sign in predicting PPCD in traumatic white mature cataracts for a suitable surgical strategy to achieve satisfactory technical and visual outcomes.