In my experience children having bilateral cataract surgery with intraocular lens implantation achieve better visual acuity in over 60% of cases compared to approx. 30-35% of children with unilateral cataract. The main reason of relatively poor visual outcome in unilateral cases is sensory deprivation leading to amblyopia much more in unilateral cases. Intensive occlusion therapy is helpful in management of amblyopia. Other complications such as visual axis opacification due to posterior capsule opacification , membrane formation, glaucoma and refractive error changes does not differ significantly in these children. What are your experiences?
In my experience children having bilateral cataract surgery with intraocular lens implantation achieve better visual acuity (20/40 i.e 6/12 or better) in over 60% of cases compared to approx. 30-35% of children with unilateral cataract. The main reason of relatively poor visual outcome in unilateral cases is sensory deprivation leading to amblyopia much more in unilateral cases. Intensive occlusion therapy is helpful in management of amblyopia. Other complications such as visual axis opacification due to posterior capsule opacification , membrane formation, glaucoma and refractive error changes does not differ significantly in these children
. Accommodation is also an important factor. Aphakic or psudophakic eye cannot accommodate for different working distances, even during active patch therapy. This sure decreases the efficacy of visual rehabilitation trials. Even ignoring amblyopia per sue; children do not feel comfortable seeing with their psudophakic eye during patch therapy which makes the prognosis worse than pure refractive amblyopia.
No doubt accommodation is one of the most important factor, what is the alternative in children operated for visually significant cataract- either implantation of intraocular lens during surgery or aphakic glasses or contact lenses in cases child is left aphakic. In children implanted with IOL, we give only near addition to residual refractive error upto approx three year age or preschool going age child and after three year age are given bifocal. Those requiring occlusion therapy such as children operated for unilateral cataract, occlusion therapy is given with optical correction on and the child is monitored. Children may not feel comfortable initially but optical correction and good compliance of occlusion therapy is must to ensure better outcome in those requiring it such as eyes with amblyopia or children operated for unilateral cataract having amblyopia.
In my clinic, we routinely try to fit aphakic children- either unilateral or bilateral- with RGP contact lenses, this help better optical correction by preventing image distortion and prismatic effect of off axis gaze and normal appearance plus avoiding mechanical pressure over child’s face by the heavy eyeglasses. Considering the ideal age for IOL implantation about 3 y for unilateral and 6 y for bilateral cases, the recommended addition is +2 D for neonates and we decrease it gradually to +1 D to consider the required working distance for each age group. The important point is recommending the ideal working distance for active patch therapy to the parents, e.g. a child with + 1D add should sit closer to TV during patch therapy to get good results. After IOL implantation, bifocal or progressive eyeglasses will help the child achieving a better range of clear vision.
The fact is unilateral cases have lower chance of gaining near normal vision despite all these efforts compared to bilateral cases.
It is better choice to fit contact lenses to those children having cataract surgery where IOL implantation is contraindicated. In several situations, particularly in the developing countries hygiene, socio-economic status and compliance is a major issue. The fact that unilateral cases has lower chances of gaining normal vision compared to bilateral cases despite best effort like occlusion therapy in children is well established. There is no controversy of performing intraocular lens implantation in children age is 2 years or above provided there is no contraindication whether it is unilateral cataract or bilateral cataract. There are several studies showing good results of cataract surgery in children over two years of age.
1. Wilson ME. Intraocular lens implantation: has it become the standard of care for children? Ophthalmology 1996; 103:1719–1720
2. Lambert SR, Buckley EG, Plager DA, Medow NB, Wilson ME. Unilateral intraocular lens implantation during the first six months of life. J AAPOS 1999; 3:344–349.
3. Crouch ER Jr, Pressman SH, Crouch ER. Posterior chamber intraocular lenses: long-term results in pediatric cataract patients. J Pediatr Ophthalmol Strabismus 1995; 32:210–218.
4. Ram J, Gupta N, Sukhija JS et al. Outcome of cataract surgery with primary intraocular lens implantation in children. Br J Ophthalmol 2011; 95:1086-1090.
5. 7. Wilson ME, Peterseim MW, Englert JA, Goldberg RL, Rosenbaum AL. Pseudophakia and polypseudophakia in the first year of life. J AAPOS 2001; 5:238–245.
Defining target refraction and IOL power calculation for younger children are major problems which make contact lns better choice for children younger than 3 years.Otherwise the surgeon should be prepared for managing either high initial hyperopia or late myopia which sometimes need contact lenses again to prevent anisokonia.
We must resolve major issues of concern in pediatric cataract surgery particularly younger then three years. The problems are as mentioned IOL power calculation, IOL sizing of IOL and how to do visual correction or rehabilitation. We do under-correction of IOL power in children 2-8 years by approx 20% and in children less than 2 years by 10%. Dahan's guidelines.These are helpful in adjusting initial hypermetropia and late myopic shift. No double contact lenses is one of the solution in managing anisokonia/ image size difference and provide full field. Still our first choice remain IOL implantation where it is not contraindicated and equally important choice is Contact lenses.
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