Biomedical subjects
Publications and source records attributed to W G Pearce.
Extraocular muscle recessions with loops of silk suture were performed in 10 dogs. When, after a 5-mm section of the medial rectus muscle was resected, suture loops 5 mm long were inserted near the functional equator (8 mm behind the muscle's original insertion) an effective pseudotendon was produced in 71% of the eyes. This procedure may be a useful addition to the surgical methods of correcting horizontal strabismus.
We recessed extraocular muscles in rabbits using loops of silk sutures. The effectiveness of the pseudotendons produced depended on their relation to the functional equator of the eye and on the length adherent to the sclera. Loops about 5 mm long inserted at or near the functional equator produced effective pseudotendons. If the loops were inserted in front of the functional equator they adhered to the sclera and the advantage of using them was negated.
A survey of 40 individuals registered with the Canadian National Institute for the Blind (CNIB) as blind from congenital nystagmus revealed that an abnormal single gene was responsible for the disorder in 33 patients. Fifteen of these were due to autosomal recessive conditions while X-linked disorders accounted for another 15 patients. In 3 cases the pedigrees were consistent with both autosomal recessive or X-linked inheritance. A clearly defined environmental origin was present in 1 case while specific genetic or environmental factors were not detected in the remaining six patients. The albinism, achromatopsia and Leber's congenital amaurosis groups of disorders were those most frequently detected.
A Newfoundland kindred in which ocular albinism and deutan colour blindness are segregating provides strong evidence against the loci for these two X-borne characters being within direct measurable distance of each other.
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Cases of conjunctival papilloma evaluated at a hospital that acts as a referral centre for native people (Indian and Inuit) from northern Alberta and the Northwest Territories were compared with those from other hospitals in the same region whose referral base is primarily non-native. When the data were standardized for population unitsof 100,000 the tumours appeared to be occurring with a greater frequency among lnuit of the Western Arctic. These findings are supported statistically, although it is possible that bias may have been introduced by the small number of cases and other related factors.
Four families with nine members affected with autosomal recessive macular dystrophy (Stargardt's Disease) and one family with six members affected with autosomal dominant macular dystrophy have been examined. Age of onset, rate of visual deterioration, fundus appearance, electroretinography and dark adaptometry have been compared in the various families. Some differences, particularly in the rate of visual deterioration and in the fundus appearance were noted between the recessive and dominant forms. Despite these differences in the clinical and related features, the genetic implications are of greater importance to the affected individuals. Genetic counselling which provides recurrence risks of the disorder in the affected individuals' siblings and children should be included in the assessment of patients with these forms of hereditary ocular disease.
During the period 1970-73, 1,046 children under 20 years of age were registered with the Canadian National Institute for the Blind. The three most common registration diagnoses were Cataract (13%), Optic Atrophy (12%) and Nystagmus (10%); Retrolental Fibroplasia was responsible for a smaller proportion (6%). Twenty per cent of the registration diagnoses were non-specific and included "Nystagmus", "Site or Type not Established", "Affection of Visual Centre" and "Amblyopia". Without a specific diagnosis one could not decide whether the blindness was due to genetic or environmental causes. It is recommended that the C.N.I.B. establish a procedure by which children with a non-specific registration diagnosis can be referred for further investigation.
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Explore the source record for details and available documents.