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Liat Gantz, Gabi Arbiv, Niva Tiri, Ariela Gordon-Shaag, Philip Fine; Objective and Subjective Comparison of Three Fitting Approaches of Rose K2 Lenses. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4663.
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© ARVO (1962-2015); The Authors (2016-present)
The Rose K2 is a back surface aspheric RGP contact lens design for keratoconus (KC) with a recommended fitting of light apical touch (AT) of 0.7 mm in the fluorescein pattern. Other studies fit these lenses either flatter or steeper than AT, which result in varied pre-corneal tear thicknesses (PCTT). The variations in corneal touch and PCTT can provide differences in optical visual quality. This prospective, non- dispensing study systematically compared standard AT with 0.1 mm flatter (FAT) or steeper (SAT) fitting approaches to determine the optimal objective and subjective fit.
The study was approved by the College IRB. Patients with varying degrees of KC, and without other ocular or systemic diseases, or corneal surgery signed an informed consent. After a self- administered ocular and medical history questionnaire, KC diagnosis was verified clinically. The base curve (BC) of the initial trial lens selected from the Rose K2 trial set was 0.2 mm steeper than average keratometric reading and with a standard edge lift. After 15 minutes of stabilization, the physiological fit was assessed using a slit lamp biomicroscope, and the BC was modified until an acceptable AT fit was obtained. The order of the three fitting approaches was randomized for each patient. For each fit, the LogMAR visual acuity, and FACT chart peak contrast sensitivity (CS) and peak CS spatial frequency (SF) were measured. Higher order (HO) aberrations were measured using the L80+ wavefront aberrometer. Outcomes were compared using one-way repeated measures ANOVA (95% significance level).
Two male and six female KC subjects between the ages of 23-35 (mean age: 28.2± 5) participated in the study. The total RMS (AT: 1.59±1.1, FAT:1.86±1.9, SAT: 2.0±1.1 (μm)), HO RMS (AT: 0.54±0.4, FAT:0.44±0.4, SAT: 0.65±0.4), coma (AT:0.36±0.3, FAT:0.29±0.3, SAT:0.50±0.4), mean LogMAR VA (AT:0.13±0.03, FAT: 0.16±0.03, SAT: 0.16±0.03) and mean peak CS (AT: 44.8±4.6, FAT: 52.3±7.8, SAT: 48.9±7.3 (%)) were not significantly different. The SF of the peak CS (AP: 5.1±0.4, FAP: 9.2±1.5, SAP: 7.7±1.5, (cpd)) was significantly different (F(df= 2,12)=6.72; P=0.005) between the AT and FAT fits (Tukey-Kramer post hoc test).
The type of RoseK2 fit does not influence most parameters of visual quality significantly. However, when debating between the AT and FAT fittings, the AT fit yields better CS performance, which can affect visual quality.
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