Relationship of Fusion Weakness to Reading Disability

Abstract

A great number of attempts have been made to isolate definite factors which might have a significant correlation with reading disability. A review of the literature on the subject does not yield evidence of any par ticular physical or mental (intelligence elim inated) status as a constant dominant factor. Previous research relative to vision as a factor in learning to read has not been able to point toward any conclusive evidence. However, the work of Paul Fendrick ( i ) in his Doctor's Dissertation on Visual Characteristics of Poor Readers, that of Emmett Albert Betts (2), and others exhibit implications which require further attention. Myopia* (near sightedness), hyperopia (far sightedness), astigmatism, and heterophoria have been considered. These, as they were found in large numbers of cases of both good and poor readers, do not account for any great percentage of reading disability. Also, since the factors of hyperopia, myopia, and astigmatism are correctable with lenses, they cannot be considered as constant. The con dition of marked imbalances, though, may be a factor contributing toward retardation. This implication is easily seen in the results of the work by Betts (4), Selzer (5), Fendrick (6), and Eames (13). In cases where muscle im balances are highly pronounced they may pro duce deviations of retinal images sufficient to cause double or blurred vision. Here the reader must compensate for this condition, hence be handicapped in learning to read. Compensation apparently results in fatigue, strain, nervousness, or confusion in the indi vidual. It should be noted that in the condi tion of imbalance where duction is normal, fusion of the retinal areas is nearly complete, or less so, according to the degree of imbal ance. It logically follows that the less com plete the fusion, the greater the need for compensation. This corollary is evident: the greater the duction strength of the recti muscles the greater the possibility for forced fusion when called upon; or conversely, the weaker the duction muscles, the less possible for them to force fusion, hence the need for compensation.