Primary posterior capsulorhexis in children
Experts compare advantages of different approaches
There has always been a debate on whether the limbal or pars plicata approach is better for primary posterior capsulorhexis in paediatric cataract surgery.
At the World Congress of Paediatric Ophthalmology and Strabismus 2017, Hyderabad, Marta Morales Ballús MD, PhD, from Spain, advocated the pars plicata route citing concerns of iris prolapse through limbal incisions as well as the possibility of vitreous strands getting caught in the wound, both of which can result in postoperative corectopia in the child if using the limbal approach.
Moreover, pars plicata approach would minimise inflammation and glaucoma, keeping the vitreous back to the IOL.
Dr Morales Ballús, St Joan de Déu Hospital, Barcelona, also noted that the pars plicata approach would be a must in cases with posterior lenticonus or posterior plaques. As many cases of paediatric cataracts also have the posterior capsule itself involved in the cataract, she argued that it would be very difficult to perform posterior continuous curvilinear capsulorhexis (PCCC) by an anterior approach, and therefore a posterior approach would be preferable.
Taking a different perspective, Ken Nischal FRCOphth, Children’s Hospital, University of Pittsburgh Medical Center, US, argued in favour of a limbal approach to the paediatric posterior capsule, stating that a primary posterior capsulorhexis via limbal approach had advantages over a posterior capsulectomy with a vitrector. In addition, it gave advantages of not having to disturb the conjunctiva, especially when operating on children younger than two years of age who have an increased incidence of glaucoma as compared to older children. Moreover, an improperly closed sclerotomy could possibly give rise to a bleb.
Dr Nischal added that in a case of an unintentionally torn anterior capsulorhexis, a manually performed PCCC could be utilised for optic capture of the IOL, whereas attempting a capture in a vitrectorhexis could result in a splitting of the posterior capsule. Since there are no definite anatomical landmarks as to the pars plana and pars plicata in children, a posterior approach may also carry a higher risk of retinal detachment.
He described his technique of two-incision push-pull rhexis to obtain a round rhexis, and the possible use of intraoperative optical coherence tomography for the posterior rhexis.
He also stressed the importance of good anaesthesia for uneventful paediatric cataract surgery. Use of propofol and a laryngeal mask alone do not reduce sympathetic activity and do not prevent positive vitreous pressure. A pCO2 less than 30mmHg and avoiding bolus injections of saline are helpful.
In addition, good paralysis prevents the eye from rolling backwards. A traction suture should be avoided to prevent distortion of highly elastic paediatric tissues and consequent increased vitreous pressure.
All these measures help avoid iris prolapse, vitreous strands and corectopia. He also added that any posterior capsular plaque could be used as a template for a posterior rhexis and encompassed within the rhexis if possible, using the two-incision push-pull rhexis.
Marta Morales Ballús:
Ken Nischal: firstname.lastname@example.org