Table 7: Adverse events of included trials.

YearAdverse events

Cho et al. [16]2005Four subjects withdrawal because of corneal complications in OK group (2 with recurrent corneal staining and 2 with inflammation.)

Walline et al. [17]2009None of the dropouts were due to complications.

Kakita et al. [18]2011In the OK group, two patients had mild corneal erosion, which improved after 1 week of treatment cessation, and subsequent OK treatment was resumed without any sequelae. No other complications, such as corneal ulcer, were noted. There were no adverse events in the spectacle group.

Cho and Cheung [19]2012One recurrent corneal inflammation was reported in the control group and the subject was excluded from the study. Five ortho-k subjects were withdrawn from the study due to ocular health issue: three had mild rhinitis resulting in corneal staining, one had increased conjunctival hyperemia, and the remaining subject developed chalazion in the right eye. Ocular conditions and vision of these ortho-k subjects were not affected after cessation of ortho-k treatment.

Hiraoka et al. [20]2012Moderate superficial punctuate keratopathy was observed in 3 subjects and mild corneal erosion was found in 1 subject in the OK group, but these conditions were recovered completely after discontinuation of lens wear for 1 week. All subjects resumed OK treatment thereafter. No other severe complications, such as corneal ulcer, were noted in the OK group and there were no adverse events in the spectacle group.

Santodomingo-Rubido  et  al. [21, 24]2012Nine OK subjects showed adverse events (i.e., corneal staining, corneal abrasion, conjunctivitis, contact lens-induced peripheral ulcer, dimple veiling, blepharitis, and hordeolum). Two of them discontinued the study. The adverse events found with OK in this study are not considered to be serious, are similar to those reported with other contact lens types, and can be managed straightforwardly in clinical practice.

Charm and Cho [22]2013Corneal staining was observed in some subjects in both groups at each visit, but the incidence was generally higher in the PR ortho-k subjects. However, all stainings observed were not significant (all were grade 1) between the two groups of subjects who completed the study. Only one subject was withdrawn from the study due to grade 2 (coverage) peripheral corneal staining in OK group. No other adverse events were reported in either group of subjects.

Chen et al. [23]2013None of the dropouts in either group of subjects was due to ocular adverse events. Although ortho-k lens wear tended to increase the incidence of corneal staining in the peripheral cornea, the staining observed was considered to be mild as depth of staining was mostly superficial (Grade 1) and the average incidence was less than 10%.