Soft and hard contact lenses worn in combination

Area of Science:

• Ophthalmology
• Biomaterials Science

Background:

• Contact lens technology aims to improve wearer comfort and ocular health.
• Corneal edema is a common complication associated with contact lens wear, particularly with extended wear.
• Combination lens systems, pairing soft and rigid lenses, are explored to mitigate adverse effects.

Purpose of the Study:

• To evaluate the effects of different contact lens combinations on corneal edema in normal corneas.
• To assess the tolerance and efficacy of ultrathin soft contact lenses combined with rigid lenses in keratoconic corneas.
• To compare visual acuity achieved with combination lens systems versus single lenses.

Main Methods:

• Five subjects with normal corneas were fitted with various combinations of soft (Soflens) and rigid (PMMA, CAB) lenses.
• Three subjects with keratoconus were fitted with ultrathin soft lenses combined with PMMA lenses.
• Corneal edema was measured after 5 hours of lens wear.
• Visual acuity was assessed for all lens conditions.

Main Results:

• For normal corneas, the combination of an ultrathin soft lens with a best-fit polymethyl methacrylate (PMMA) or cellulose acetate butyrate (CAB) lens resulted in the least corneal edema.
• Two of three keratoconic subjects tolerated the ultrathin soft lens and PMMA lens combination for 5 hours, with corneal swelling of 1.7% and 5.3%.
• All subjects achieved better visual acuity with combination lens systems than with soft or hard lenses worn alone.

Conclusions:

• Ultrathin soft contact lenses, when combined with appropriately fitted rigid lenses, can reduce corneal edema in normal corneas.
• Combination contact lens systems offer improved visual acuity compared to individual lens types.
• Further investigation into combination lens systems may lead to enhanced contact lens therapies for various corneal conditions.