The therapeutic use of soft contact lenses.

Introduction Hydroxyethylmethacrylate (HEMA) is a hydrop~ylic absorpt1ve hydrogel of good mechanical strength which can, in the dehydrated state, he la;the cut to accura'te dimensioIlls and then rehydrated to form a softconta,et Jens of excellent optical properties. Lenses intended for correction .of ametropia (usually myopia) have a water content of 30 per cent to 40 percent hut the ma:terial can be made with a water Icontent oil' up ito 85 per :cent. The ,author's experience has been limited to HEMA lenses of 72 per cent 'water cDntent I~Hydroflex 72-JWOHLK). The lenses, !Which must be stored in saline solution, are flopp.y, Ibowl-shaped struotures, perfectly transp.arent and diffioult to' see when '1n liquid or on the cornea. FiJtting is !fa'r from critical, l1he radius oIf curvature ,of the lens being selected at about 1.3 mm greater than that of tbeoornea, so ,thrut the lens is significantly flatter than the corneal curve. A satIsf.aotorily lfitted lens !Will move :slightly on blinking. Lenses can easi.ly ibe removed ;by pinching :them off the cornea with finger and thumb, hut may, !With advantage, be !Worn continuously, day and night, for very long periods. In lasymptoma;ticoases, ,the very minor in~tial d.~scomifort is soon forgotten. In patients ,with severe Isymptoms these lens afford so much immediate and dramatic relief that ,their use would ibe jusitified on this ground alone. Although not intended to :be optical aid.s, Ibandage lenses often provide a significant visual improvement especially in cases ,where pathology, such as cornea,l ulcer:ation, has caused irregularity of the Icomeal surface.