Posterior lenticonus with persistent fetal vasculature.

A 10 year old girl present with both eyes central cataract with posterior lenticonus. Intraoperative, she was noted to have both eyes persistent fetal vasculature (PFV). To the best of our knowledge, association of bilateral posterior lenticonus and PFV has not been reported before. This supports the hypothesis that PFV has a role in pathogenesis of posterior lenticonus.

Posterior lenticonus is a localized, well-demarcated bulging of the posterior capsule and cortex of the lens. It occurs in approximately 1–4 of every 100,000 children and is mostly unilateral in 8–10% cases.[12] Persistent fetal vasculature (PFV) is a congenital anomaly where primary vitreous and remnants of hyaloid artery system fail to regress. Bilateral posterior lenticonus with PFV is an extremely rare entity. This association may help in understanding the pathogenesis of posterior lenticonus.

Case Report

A 10-year-old girl presented with complaints of difficult in seeing distant objects and abnormal eye movements since early childhood. There was no family history and examination of parents and siblings revealed no abnormality. Her best corrected visual acuity (BCVA) for distance in both eyes was 5/200 and for near was less than N-36 and she had nystagmus. On slit lamp examination, she had both eyes posterior lenticonus with associated posterior subcapsular and cortical cataract in the central 5 mm area which was confirmed on ultrasound biomicroscopy (UBM). [Fig. 1] Peripheral fundus was normal limit while disc and macula could not be visualized. On ultrasound, A-scan revealed normal axial length and B-scan showed no abnormality.

Figure 1

Posterior lenticonus. (a, b) Clinical picture of right and left eye, respectively, showing central cataract with bulge posteriorly. (c, d) Ultrasound biomicroscopy of the same showing bulging of the lens

Patient underwent lens aspiration in the right eye during which a thin stalk of PFV was noted connected to the bulge in posterior capsule. Intraoperative fundus evaluation revealed stalk attached posteriorly to the disc. [Fig. 2] Because the stalk was avascular, during surgery it was cut using vitrectomy cutter at the time of posterior vitrectorhexis. Posterior chamber intra ocular lens (IOL) (multipiece) was implanted in the sulcus with optic capture. During left eye surgery, after lens aspiration, Mittendorf dot was noted on the posterior capsule nasal to the center. On fundus examination stalk of PFV was noted attached to the disc. Posterior chamber IOL was implanted with similar technique. Postoperatively, she improved to a BCVA of 20/100 in each eye and near visual acuity of N-10 with near correction.

Figure 2

Persistent fetal vasculature. (a) Right eye showing stalk of PFV nasally attached to posterior capsule. (b) Fundus picture (inverted) of the same intraoperative showing stalk of PFV attached to the disc (black arrow). (c) Left eye showing Mittendorf dot seen nasally on the posterior capsule. (d) Fundus of the same showing stalk of PFV attached to the disc (red arrow)

Discussion

Posterior lenticonus is a congenital defect, which is sporadic and unilateral in most cases.[123] Its pathogenesis is not known. Bilateral cases have been reported and are generally associated with a positive family history.[4]

It may be due to thinning of the posterior capsule with bulging of the cortex from the thinned out area into the vitreous cavity, which has been corroborated with histopathological evidence.[5] This could be genetically determined in bilateral cases.

It could also be due to remnants of hyaloid artery system causing traction on posterior capsule. This was hypothesized by Mann et al.[6] in 1957 but has not been proven. An isolated patient of unilateral posterior lenticonus with PFV has been reported.[7] Our patient had bilateral posterior lenticonus with PFV in both eyes, which suggest that posterior lenticonus could have been caused by the traction from the hyaloid artery system which started regressing later. In cases of posterior lenticonus without any PFV, PFV may have regressed after causing traction which led to the thinning and bulging of posterior capsule.

Surgery in such cases can be challenging. Surgical techniques from anterior route as well as pars plana lensectomy have been described.[1] We performed lens aspiration followed by posterior vitrectorhexis, cutting of stalk and placing IOL with optic capture. Posterior capsule can be spared in older children and later on Neodymium: YAG capsulotomy could be performed. Since our patient had nystagmus, we preferred primary capsulotomy. Our patient improved after surgery despite late presentation and presence of nystagmus, which suggests that attempts should be made towards visual rehabilitation in such patients.

Conclusion

In conclusion, we think that remnants of hyaloid artery system may play a crucial role in pathogenesis of posterior lenticonus. PFV may be underdiagnosed in such cases. Hence, a high suspicion can help in diagnosing cases with subtle presentation.

Declaration of patient consent

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Conflicts of interest

There are no conflicts of interest.