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Biomedical subjects

M Ruben

Publications and source records attributed to M Ruben.

At least 55 records · Page 3Linked to original sources

Aetiology of keratoconus.

Keratoconus has a common association with atopic conditions. Most keratoconus patients rub their eyes excessively. Eye-rubbing is considered the dominant aetiological factor in two-thirds of patients with keratoconus who progress to contact lens wear. A classification of keratoconus based on the dominant aetiological factors is proposed. No significant psychoneurotic factor was found in the keratoconus patients compared with patients in the control group.

Adult↗

Clinical manifestations secondary to soft contact lens wear.

The study of 151 patients wearing soft hydrophilic lenses for one year revealed no gross irreversible lesions with loss of vision. But of significance was the presence of superficial lesions of the corneal epithelium, and chronic stromal oedema. While no significant loss of wearing time was noted for women taking the pill, the decrease in tear secretion in those patients with a latent dry eye problem could just alter the balance to produce intolerance. From this report it is the long-term changes to the tissues that remain to be fully investigated for soft hydrophilic lenses.

Blepharitis↗

The 1972 Cuban national child growth study as an example of population health monitoring: design and methods.

A stratified 3-stage random sample of 50 360 children ages 0-19 drawn from the whole population of Cuba was measured in a large-scale growth study during 1972-73. Fifteen anthropometric measurements were taken and puberty stages and menarche status were assessed. Hand-wrist radiographs were done on 10% of the sample. Information regarding the social and education status of the parents was obtained and parental heights were measured. One year later, 30% of the sample were re-measured and 10% re-X-rayed. The overall response rate was 96% at pre-school and primary school age, and a lettle less later. Quality control sessions were held at which the nine measuring teams compared results. No significant differences were found between teams working different parts of the island. Differences between duplicate measurements of stature by individual measurers had standard deviations approximating 0.20 cm. Individual measurers' means differed from the grand means of all measurers by up to +/- 0.2 cm for stature, +/- 0.4 cm for sitting height and +/- 0.5 mm (7% of mean) for triceps skinfold. One or more measurements lay outside the 3rd-97th centile limits in 21% of individuals. Scrutiny of these individuals' records resulted in elimination of measurements in amounts ranging from 0.1% (triceps skinfold) to 1.1% (crown-rump length). Problems of planning and execution of growth surveys designed to set national standards are described, and solutions given or suggested.

Adolescent↗

Fibrillary lines of the cornea. A clinical sign in keratoconus.

Fibrillary lines, whether in the normal cornea or in keratoconus, are faint structures which must be searched for diligently with the appropriate biomicroscopical settings, using a high magnification and oblique focal illumination of high intensity. They are unlikely to be confused with other superficial linear changes in the cornea, such as mare's tail epithelial lines, fingerprint lines and their variants, ring lines, and so on. A detailed description of these and other entities is given elsewhere (Brown and Bron, in preparation).

Cornea↗

Calcium deposition as a cause of spoilation of hydrophilic soft contact lenses.

A series of 75 spoilt soft lenses with opacities (mostly manifesting as discrete spots or as large areas of cloudiness, chalk-white in appearance) were subjected to histochemical, electron microscopical, electron probe x-ray microanalytical, x-ray diffraction, atomic absorption spectro-photometric, and biochemical analyses. The results showed that in many cases calcium was implicated in the deposit formation and that a broad correlation existed between the amount of calcium present and the degree of opacification. The possible mode of calcium deposition and resulting implications in lens intolerance are discussed. It is advocated that a search should be made for a modified or new soft lens material which does not permit calcium deposition, and that the medical practitioner should strive towards improved assessment of the systemic and ocular conditions which may help in identifying patients at risk of early lens failure.

Calcium↗

The paretic pupil: its incidence and aetiology after keratoplasty for keratoconus.

The present study reveals that pupillary abnormalities are common after keratoplasty for keratoconus and that, in addition to the fixed dilated pupils which we have found in 7.8 per cent. of eyes, varying degrees of partially dilated pupil frequently occur after operation. In our experience, glaucoma is not a sequel to the simple paretic pupil, a finding which confirms the results of the smaller series of Alberth and Schnitzler (1971); glaucoma thus seems to be no more a special complication of keratoplasty for keratoconus than it is of keratoplasty for any other corneal pathology. The paretic pupils can be explained on the basis of ischaemic atrophy of the sphincter pupillae muscle secondary to an iris strangulation phenomenon occurring during surgery in the manner we have discussed. The relative frequency of a dilated pupil, together with the common finding of focal iris atrophy after minimal surgical trauma to the iris in cases of keratoconus, forces one to conclude that the pathology in this condition is not confined to the cornea but probably extends to the iris and possibly to the scleral envelope as well.

Atrophy↗

Pilocarpine dispensation for the soft hydrophilic contact lens.

The use of hydrophilic soft contact lenses for dispensation of pilocarpine is described. The release rate of pilocarpine from three materials of different water content was estimated and from this the surface concentrations were calculated. It is estimated that PolyHEMA can after 15 hours provide a 1 per cent surface concentration of pilocarpine, whereas higher water content materials (70 and 85 per cent) halve this, although they provide a much higher concentration in the first few hours of use. These results are based upon pre-soaking in 4 per cent pilocarpine solution. Because contact lenses present a management problem, this method of dispensation will be used only for selected cases. Some clinical examples treated successfully over a 20 month period are discussed.

Contact Lenses, Hydrophilic↗

What is a soft lens?

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Biomedical Engineering↗

Contact lenses.

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Contact Lenses↗