Contact lenses as the best conservative treatment of newly diagnosed keratoconus--epidemiological retrospective study

Abstract

Keratoconus is a progressive, non-inflammatory corneal ectasia characterized by thinning and weakening of the corneal stroma which results in its' protrusion. The onset is during puberty and progresses until the fourth decade of life. In earlier stages, good visual acuity can be provided with spectacles. With progression, contact lenses are considered to be a better therapy. Aim of this study was to determine if there is statistically significant difference between best corrected visual acuity (BCVA) obtained by spectacles and contact lenses in newly diagnosed keratoconus patients, as well as to determine which type of contact lenses provide better BCVA in keratoconus patients. We conducted a 5-year retrospective study of all 2891 patients attending our Contact Lens Department for the first time, searching for patients newly diagnosed with keratoconus. Data were obtained on gender, age, education level, treated eyes, corneal changes, keratoconus severity, BCVA with spectacles, contact lenses and best fitted contact lens type. All patients underwent standard ophthalmic exam, refractometry and keratometry have been done, followed by a spectacles correction and lens fitting. Wilcoxon signed rank test was used for statistical analysis. Results showed that of all 2891 patients examined for the first time, 137 patients (4.74%) have been newly diagnosed with heratoconus, there was male bias (72.26%), mean age 27.7 +/- 9.9 years. Most patients had high school education (51.11%), 3.70% had present corneal changes, 50.37% had mild heratoconus. Majority had keratoconus on both eyes (36.3%) or keratoconus of right eye (26.67%). There was a statistically significant difference (p<0.001) between the BCVA obtained with contact lenses (0.82 +/- 0.21 Snellen chart) rather than spectacles (0.37 +/- 0.27 Snellen chart). The best corrected visual acuity was achieved with rigid gas permeable (RGP) lenses in majority of kera- toconus eyes (51.85%), with semi-gas permeable (SGP) lenses in 43.39%, in 4.23% with polymethyl methacrylate (PMMA) lenses and with hard-soft gas permeable (GP) contact lenses in 0.53% of keratoconus eyes. We have showed that there is a statistically significant difference in BCVA achieved better with contact lenses than with spectacles. RGP lenses are most frequently used in conservative treatment of heratoconus, but SGP lenses were also shown to be a good option that gives equally satisfying final visual acuity with subjective comfortable feeling of contact lens wear.