Free Health Dissertations - Many Of The Genetic Disorders Which Can Cause Visual Impairment Can Be
Many of the genetic disorders which can cause visual impairment can be predicted (at least in statistical terms) and the children specifically assessed at birth (12)
The majority of the papers examined with regard to infantile cataract are of the same opinion that early treatment is vital to secure any hope of reasonable visual acuity. The evidence base for some other conditions of visual impairment is nowhere near as clear, and in some places, frankly contradictory.
If we consider the implications for other conditions of visual impairment in childhood we should consider the paper by Clarke MP (13) which specifically considers the efficacy of treatment of a unilateral visual impairment in the 3-5 yr. old age range. This is particularly relevant to our considerations here because the trial itself was well constructed and has a meaningful outcome. In broad terms, nearly 200 children who were identified as having a degree of unilateral visual impairment were allocated into two groups.
One group had appropriate treatment the other had no treatment. The authors note that all children had treatment after the six month observation period. the children who received full treatment with glasses universally had better visual acuity than those who did not receive treatment. Interestingly, the mean treatment effect between the two groups was only one line on the Snellen chart. The degree of improvement was proportional to the degree of original impairment. The specific conclusions of this particular study are worth quoting verbatim:-
Treatment is worth while in children with the poorest acuity, but in children with mild (6/9 to 6/12) unilateral acuity loss there was little benefit. Delay in treatment until the age of 5 did not seem to influence effectiveness.
It is worth considering these conclusions in more detail as they have distinct relevance to the need for early intervention. The authors point out that there is a tendency for amblyopia to undergo a degree of spontaneous improvement which is consistent with the results of another trial (14).
It is also fair to point out that other trials do not concur. Simons K (15) suggest that untreated amblyopia will deteriorate with time. The authors feel that, on balance, they recommend the continued wearing of glasses until the age of 7, even if the visual acuity returns to normal before this time, to prevent the development of refractory amblyopia. (16)
When the authors compared the results of their study with children from districts who did not receive pre-school screening, the follow up study showed that deferring their treatment did not limit their potential for improvement and, very significantly, it nearly halved the number of children that needed to wear eye patches at all.
Dissertations - Free Health Dissertations
