A simple formula is developed to give the thickness of a lens at various distances, measured radially, from the optical centre when the centre thickness, index of refraction and the power of the lens are known.
A simple formula is developed to give the thickness of a lens at various distances, measured radially, from the optical centre when the centre thickness, index of refraction and the power of the lens are known.
A 35-year-old woman was referred for contact lens fitting. The patient had undergone four radial keratotomy procedures in each eye between 1989 and 1990. A total of 32 radial keratotomy incisions were made on each cornea. The patient was dissatisfied with both her uncorrected visual acuity as well as her best-corrected visual acuity as obtained by speectacle correction. She also reported disturbing symptoms of asthenopia. She was successfully prescribed bitoric RGP lenses.
A study was undertaken to establish whether contact lens patients are likely to be more compliant with their lens careregimes if they pay a fair and proper price for their health goods because the worth' of these goods is reinforced. Fifty-nine patients were recruited into two groups (‘nominal’ or ‘ful’ pay). After 4 months the amount of solution actually used was compared with the estimated amount. More cleaning solution was actually used by patients in the ‘nominal pay’ group, but less saline and protein remover tablets were actually used by patients in both groups (P<0.05). Corneal staining was significantly more apparent in the ‘nominal pay’ group (P<0.05). Eight aspects of lens hygiene were assessed. Only 11 % of patients were compliant in all aspects but no statistically significant difference was found between patients in the two groups. In this short-term study, cost did not appear to affect the level of compliance.
A 31-year-old man presented at an optometric clinic because of reduced vision and loss of lens quality. There was mild limbal injection and staining in both eyes. The soil fungus Exophiala jeanselmei as well as Serratia marcescens, Klebsiella aerogenes, Escherichia coli and Alcaligenes xylosoxidans were cultured from the contact lenses and the storage case fluid. E. jeanselmei is recognised as an opportunistic fungal pathogen and is known in one instance to have infected the cornea. Discernible invasion or infiltration of the cornea may not have occurred in this instance owing to the physiological status of the wearer. Intermittent short-term lens wear may have reduced the likelihood of hypoxia and corneal oedema.
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