Lunar lenses – Acquired lens colobomasS Choudhary, D Katoch, SS Pandav, S Kaushik
Advanced Eye Centre, Post Graduate Institute of Medical Education and Research, Chandigarh, India
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/jpgm.jpgm_1145_21
Source of Support: None, Conflict of Interest: None
Keywords: Acquired lens coloboma, cryopexy, optical iridectomy
A coloboma is a term used to describe a localized absence of any ocular structure, which may be a developmental malformation or have an acquired cause. An “acquired lens coloboma” appears as a notch or flattening of the lens margin because of the localized zonular absence. It is technically a misnomer because there is no actual absence of the lenticular substance. The localized loss of tension on the lens capsule results in retraction of the unsupported lens portion, giving the appearance of a lens defect. Careful clinical examination reveals the absence of zonules in the area of the coloboma. Isolated developmental lens colobomas are uncommon, and they usually occur in association with a ciliary body, iris, or choroidal coloboma.
Acquired zonular disruption could occur secondary to an abnormally stretched eye, as seen in buphthalmos. We have previously reported a developed lens coloboma in a child with neglected congenital glaucoma. It has also been reported as a consequence of disruption of the weak zonules in Marfan's syndrome with axial elongation of the globe.,
We describe two cases of acquired lens coloboma in two infants with glaucoma who underwent ocular surgery. One was likely because of direct trauma during an optical iridectomy, and the other was noticed on the examination after scleral buckling for retinal detachment.
A 1-year-old boy diagnosed with newborn glaucoma had a residual central corneal opacity after glaucoma surgery, obscuring the visual axis [Figure 1]a. He underwent an inferonasal optical iridectomy in the left eye with a vitreous cutter. On follow-up, the lens looked like a bitten apple [Figure 1]b. There was a coloboma with broken zonules in the area of the deformity.
An 8-month-old baby (born at a gestational age of 28 weeks) was diagnosed with right eye buphthalmos 5 months following a scleral buckle surgery. He had previously presented at 3 months of age with rhegmatogenous retinal detachment in the right eye, for which he underwent a scleral buckle with inferotemporal cryopexy. No lens abnormality was noted during surgery [Figure 2]a. We suspected Stickler's syndrome, but the systemic evaluation showed no abnormality, and the caregivers did not consent for genetic testing. Five months following surgery, the baby presented with a cloudy cornea and buphthalmos in the operated eye [Figure 2]b. The child had already undergone a scleral buckle explant 2 months prior to this for the suspicion of developing buphthalmos. We noted a localized lens coloboma in the inferotemporal quadrant during examination under anesthesia (EUA) [[Figure 2]c, white arrow]. This was also the area of the primary break and cryopexy [Figure 2]d. Focal lenticular opacities were also noted [[Figure 2]c – yellow arrow].
Subtle acquired lens colobomas are likely to be missed on examination as they may not get noticed under the peripheral iris, and zonular injuries during ocular surgeries may be missed. A thorough ophthalmic examination with a dilated pupil is necessary in the post-operative period.
In the first case, the coloboma most likely occurred because of accidental zonular injury at the time of the optical iridectomy. Abnormally stretched zonules may also have been an underlying pre-disposition. Care while doing an iridectomy with the liberal use of a cohesive visco-elastic substance between the iris and lens may help avoid this complication. In the second baby, the coloboma may have arisen secondary to an accidental zonular injury during retinal detachment surgery and the cryopexy procedure. The other possible reason could be the development of coloboma because of zonular stretching secondary to buphthalmos development after scleral buckling as reported by Dhingra et al. Under conditions of extreme stretching such as buphthalmos, lens zonules may eventually rupture and leave the lens edge un-taut. Such lens edges then shrink and develop a localized concavity or acquired lens coloboma. An acquired lens coloboma in secondary buphthalmos is not hitherto reported, but it is important to keep this possibility in mind while planning the follow-up schedule for buphthalmic eyes.
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[Figure 1], [Figure 2]