Journal of the British Contact Lens Association, Vol. 14, No. 3, pp 115-127, 1991 ©1991 British Contact Lens Association Printed in Great Britain THE AGING EYE AND CONTACT LENSES- A REVIEW OF OCULAR CHARACTERISTICS Russell L. Woods* (Received 18th March 1991, in revised form 20th May 1991) Abstract -- Most contact lens practitioners are dealing with an increasing number of otherwise healthy 'older' (presbyopic) patients. Examination of the literature indicates a persistent theme of age-related change, which generally becomes significant after the fourth decade. This review documents changes that are reported in the ocular adnexa, tear film, cornea, pupil, intraocular pressure, refractive state, spectral transmission, and chromatic aberration. The effects of these various changes on the fitting and wear of contact lenses by older patients are discussed. KEY WORDS: Age, aging, review, tear film, cornea, pupil, ocular media, spectral transmission, chromatic aberration, intraocular pressure. Introduction T HE NATURE of contact lens fitting is likely to alter slowly as population demographics in all the western nations indicate a trend towards an aging population. This change to the classical population pyramid is enhanced by the post-war 'baby boomers', who are now entering the presbyopic age bracket. In addition, many of the patients fitted with contact lenses since their introduction are now entering this group and expecting a contact lens correction of their presbyopic visual problem. Ocular changes that are acknowledged to occur with age and that may influence contact lens wear include decreased tonus of both upper 1,2, and lower eyelids 3, a reduced palpebral aperture ~,5, decreased lacrimal secretion ~,7, reduced tear stability s,9 changes to the cornea and ocular media, decreased pupil diam- eter 4,1°,11, and the effects of the increased intake of systemic drugs. ~2,13 Weale 14,15 has given a very comprehensive review of ocular age-related changes. Aspects of such changes to ocular characteristics with regard to lens wear are discussed in this article. Visual performance changes with age include the decrease in visual acuity 1~(which is greater under reduced levels of illumination17), the reduction in contrast sensitivity for high and intermediate spatial frequencies 1~2°, re- duced stereoacuity 21,22, and increased glare sensi- tivity. 23,24All of these factors are of importance when fitting contact lenses to the aging eye. Physiological considerations may be different and visual performance generally reduced. Particular care must then be taken with contact lens modalities that compromise aspects of vision, for example, monovision and bifocal contact lenses. The older contact lens patient can present special problems to the practitioner, in addition to presbyopia. Older patients may require fitting of aphakic or therapeutic contact lenses. This will often involve the use of extended-wear contact lenses, as older patients will often experience handling difficulties. Most * BOptom (Hons) MBCO advanced contact lens texts provide information about non-routine contact lens fitting requirements for older patients. Phillips 25, for example, has produced a useful review. Interest in bifocal contact lenses is increasing within the industry and the optical professions, and amongst the general public as they become aware of the option through the general and optical media. Contact lens companies are developing and publicising hydrophilic versions of the rigid bifocal contact lenses, as used by a limited number of experienced practitioners for many years, and new diffractive bifocal contact lenses are becoming available. Further development of bifocal contact lenses, the marketing capabilities of the large companies, and increased acceptance of contact lenses as a potential modality may lead to an increase in the number of presbyopes fitted with contact lenses. Despite this enormous potential market, surveys of contact lens fitting patterns 2~2s indicate that only 1% of contact lens patients are fitted with bifocal lenses. A slightly larger group are fitted with the alternative presbyopic contact lens option (monovision), the most successful system 26, but considered by many practitioners to be unsatisfactory due to its deleterious effects upon binocular vision. 2~1 The proportion of contact lens patients who are presbyopic and the proportion of presbyopes who wear contact lenses are uncertain, but are generally assumed to be small. Despite this, as mentioned above, practitioners are likely to encounter an increasing number and proportion of presbyopic contact lens patients. With this in mind, some of the special ocular problems that may influence contact lens fitting and wear are reviewed herein. Ocular Adnexa There are marked alterations with age to the tissues of the ocular adnexa, due to a 'progressive loss of tone and bulk'2 2 Changes with age to the eyelids, including a loss of tonus, reduced movement, and the reduction 115