Hybrid Versus Rigid Gas Permeable Lens In Keratoconus: Objective and Subjective Evaluation (original) (raw)

Purpose: To compare both objective and subjective outcomes of two designs of contact lenses used for management of keratoconus, the first one is an RGP lens namely Rose K2 and the second is a Hybrid lens namely Nissel Combined Comfort lens. In addition, fitting techniques, parameters and final expectation are compared and discussed. Methods: The study was conducted on selected keratoconic patients successfully fitted with Rose K2 lenses for at least 6 months earlier. The selected patients were fitted with the Nissel Combined Comfort design and followed for at least 6 months. The patients data were collected including age, sex, simulated keratometry readings, uncorrected visual acuity, refraction and fitted lens parameters. The measurable outcome data included the best corrected visual acuity with each design of contact lenses, over refraction, contrast sensitivity and glare levels, duration of lens use, and comfort grades. Subjective complaints included visual problems, discomfort, handling difficulties, cost implications, issues related to contact lens care and desire to discontinue. Objective complications included superficial punctate keratitis (SPK), corneal epithelial defects or abrasions, corneal edema, pannus, neovascularization, dry eye syndrome (DES), blepharitis, allergies and giant papillary conjunctivitis (GPC). Lens problems including tight lens syndrome (TLS), lens scratches or depositions, lens decenteration, and broken or torn contact lenses were also demonstrated. Results: Forty eyes of the 22 patients of previous Rose K2 lens wearers met the entry criteria and were fitted with Nissel Combined Comfort lenses. Fitting was easier with higher level of manufacturing perfection of Rose K2 lens than Combined Comfort one. No significant difference was noted neither in the post fitting visual acuity nor the over refraction between the two designs. On the other hand the contrast sensitivity and glare levels were higher in eyes fitted with Rose K2 lens. The patients recorded more score of comfort with hybrid lenses. Most of the fitting problems such as SPK, epithelial abrasions, DES, lens decenteration scratches, broken or lost contact lenses were demonstrated in higher percentage with RGP lens wear. Allergies, GPC, TLS and handling difficulties occurred more with hybrid lens wearers compared with RGP lens. No cases of pannus, neovascularization, corneal edema or corneal ulcers were noted in the current study with either design.