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B.B. Fresco, D.S. Rootman; A Novel Piggy Back Contact Lens Technique for Keratoconic Distorted and Post Keratoplasty Corneas . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1307.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the clinical efficacy of a novel piggy back contact lens design on a group of 40 moderate to advanced keratoconic patients and 5 non keratoconic distorted cornea patients previously unable to tolerate a rigid gas permeable contact lens. Previous piggy back systems have utilised various base lenses, in this study they were standardised. Two of the non keratoconic cases were post PKP with amniotic membrane and stem cell implantation. Two others were post RK.
Plus power silicone hydrogel lenses were implemented as the base lens in a piggy back system. The high modulus of the base lens material and the lenticular plus design provides advantages in centration and fitting of the rigid lens. Optimal rigid gas permeable contact lens fitting was undertaken over the base lens in a custom fashion for each patient. A comfort and vision questionnaire was given to each patient.
The VA with correction was 20/25 or better in 93% and better than 20/30 in 100% of cases. The wearing times were greater than 10 hours in 80% of the patients, and comfort was described as significantly better than rigid contact lenses alone. There were no clinically significant adverse effects noted in any of the piggy back fittings. There were two cases who were fit with a semiscleral lens because of inabilty to centre a rigid lens in a piggy back fitting.
A successful mode of correcting distorted corneas both keratoconic and non keratoconic is described with implications for patients with distorted corneas who are unable to tolerate a rigid gas permeable lens, and may allow delay of keratoplasty.
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