The purpose of this study was to evaluate the effectiveness of orthokeratology (OK) lenses with an increased comparison factor (ICF) of 1.75D in the treatment convergence insufficiency (CI) exophoria (EP). This was a prospective, self-controlled study of 60 eyes (30 patients) with childhood myopia, aged 8–15 years with CI EP. The OK lens was worn for a minimum of 8 hours/night. Median age of children was 10 years; 12 females and 18 males. Mean baseline refraction was -2.00D. Mean near point of convergence (NPC) was 21 ±4.54cm before lens use, 14.80 ±3.53cms 1-month after use (p=0.001), and 10.03 ±9.67cms at 3 and 6 months. Of those with NPC ≥25cms at baseline, 83.3% achieved NPC ≤10cms post treatment at 6 months. From baseline to 6-months follow-up, mean near positive fusional vergence improved from 10.63 ±2.37 to 24 ±2.26PD; mean monocular amplitude of accommodation from 6.47 ±1.68 to 12.03 ±1.38D; and mean near XP angle from 6.83 ±1.44PD to 4.90 ±1.30PD. All changes were significant at p=0.001. Increased comparison factor was 1.75D vs conventional ICF of 0.75D. There was extra for treatment of CI and this was considered equivalent to over-minus effect. The authors conclude their study results indicate potential for OK lens with ICF as a treatment option for CI with myopia. However, this requires further large-scale study.
Orthokeratology lens treatment for exophoria of convergence insufficiency type
Reviewed by Fiona Rowe
Effects of orthokeratology in patients with convergence insufficiency exophoria and myopia.
CONTRIBUTOR
Fiona Rowe (Prof)
Institute of Population Health, University of Liverpool, UK.
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