Fig. 18.1
The surgical procedures for posterior capsular plaque. (a) Posterior capsular plaque; (b) continuous curvilinear capsulorhexis (CCC) is performed after trypan blue staining; (c) irrigation and aspiration of lens cortex; (d, e) removal of the posterior capsular plaque by tearing; (f) radiofrequency diathermy capsulotomy is performed to generate a posterior capsule opening with continuous margins; (g) anterior vitrectomy is performed; (h) anterior and posterior capsulorhexis openings at the end of the surgery
18.2 Posterior Polar Cataract
18.2.1 Causes and Clinical Manifestations
Congenital posterior polar cataract can be inherited in an autosomal dominant pattern, and its possible genetic loci are 11q22–q22.3, 16q22, 14q22–23, or 20p12–q12 [3–6].
Posterior polar cataracts are often bilateral with the opacity located in the posterior lens cortex or beneath the posterior capsule. They manifest as dense white opacification with well-defined boundary (Fig. 18.2) and are likely to be accompanied by posterior capsular defect [6]. Posterior polar cataract can be divided into stationary or progressive based on whether the opacification develops over time [7]. Stationary posterior polar cataracts account for approximately 65 % of all cases and manifest as the well-defined round opacity in the central posterior capsule with concentric rings of opacification at the periphery, resembling a “bull’s eye.” Sometimes the opacities of the posterior pole are concealed by the opacified nucleus. Progressive posterior polar cataracts originate from opacities in the posterior polar cortex. They manifest as opacified radiating rings with fan-shaped margins and unclear borders, which do not involve the nucleus. In most cases of pediatric posterior polar cataract, it is difficult to determine the presence of posterior capsular defect preoperatively.
Fig. 18.2
Posterior polar cataract
18.2.2 Surgical Techniques
In posterior polar cataract extraction, attention should be given to the following issues:
- 1.
During hydrodissection, gentle maneuvers and slow, multi-quadrant injections are warranted. The position of the lens material must be closely observed, and if there are signs of downward movement, hydrodissection should be stopped without delay. It is recommended that hydrodissection can be performed in close proximity to the nucleus to form a thick cortex cushion beneath the nucleus, which will facilitate safe removal of the lens materials.
- 2.
During cortex aspiration, the height of the bottle and the flow should be lower; the cortex at the periphery is first removed and finally the cortex at the center of the posterior pole.
- 3.
The posterior polar opacity can be removed by PCCC using a cystotome, capsulorhexis forceps, or capsulotomy with radiofrequency diathermy.
- 4.
The selection of the fixation site for intraocular lens (IOL) haptics mainly depends on the location and the size of the posterior capsular defect. In-the-bag fixation is the most ideal option. If the posterior capsular defect is too large, ciliary sulcus fixation can be an alternative.
- 5.
An anterior vitrectomy device is recommended to remove the vitreous strands in the anterior chamber and part of the anterior vitreous in case of intraoperative vitreous prolapse (Fig. 18.3).
Fig. 18.3
The surgical procedures for congenital posterior polar cataract. (a) Posterior polar cataract; (b) anterior continuous curvilinear capsulorhexis is performed; (c) hydrodissection; (d) removal of the lens cortex; (e) the posterior polar opacity can be seen after the removal of lens cortex; (f) removal of the posterior polar opacity with a cystotome; (g) anterior vitrectomy is performed; (h) a second capsulotomy to enlarge the anterior capsulorhexis opening; (i) in-the-bag IOL implantation
18.3 Posterior Lenticonus
18.3.1 Causes and Clinical Manifestations
Posterior lenticonus refers to the congenital thinning and progressive backward bulging of the posterior capsule (Fig. 18.4). It usually occurs as a unilateral condition with most cases being sporadic and some being an X-linked hereditary disorder [8].
Fig. 18.4
(a) An image of posterior lenticonus obtained from slit-lamp biomicroscopy examination; (b) an image of posterior lenticonus obtained from Pentacam examination
Under slit-lamp biomicroscopy with retroillumination, posterior lenticonus appears as an oil drop-like lesion at the center of the lens against the red background illumination. Retinoscopy reveals a characteristic movement of light strip indicating that the refractive status at the center is myopic but hyperopic at the periphery. The sizes of posterior lenticonus are varied. Sometimes a localized opacity can be seen at the posterior of the lenticonus, where the posterior capsule may be absent or backward bulging and expansion of the posterior capsule may occur, giving rise to a diverticulum-like lesion. Forward progression of the opacity might occur and involve the cortex and nucleus.
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