It is believed that AC, through inflammation, may contribute to the development and progression of myopia through remodeling of the scleral matrix. Photo: Robert Ensley, OD, and Heidi Miller, OD. Click image to enlarge.

A recent study appearing in Contact Lens and Anterior Eye assessed the impact of ocular allergy on the efficacy of myopia control with orthokeratology (ortho-K). The research is novel in that this is the first study conducted to analyze this scenario, according to the research team from Wuhan, China.

The retrospective case-control study included a total of 309 patients aged eight to 15 who were all fitted with ortho-K lenses. Kids were divided into two groups—those with or without allergic conjunctivitis (AC)—based on medical history and physical signs at initial lens fitting. Three-year follow-up was conducted to document all corneal adverse events and the increase in axial length (AL) of eyes after three years wear of ortho-K.

The AC group included 47 patients, while 262 were categorized as having no episodes of ocular allergy. The researchers found no differences between the two groups in terms of age, sex, spherical equivalent, AL or environment. However, after three full years of ortho-K wear, axial elongation was significantly greater in the AC group than in the unaffected group, with average growth measurements of 0.96mm and 0.69mm, respectively. What’s more, the duration of ortho-K lens discontinuation due to corneal adverse events was greater in the AC group than the non-AC group during the three-year follow-up. Among the allergic conjunctivitis group, 42.6% experienced adverse events vs. only 28.6% without AC.

These results are indicative of ocular allergy undermining the effect of ortho-K lenses for myopia control, the researchers argue. In the discussion section of their paper, the authors propose that two main explanations for this outcome may be allergic inflammation and duration of lens wear cessation.

Children wearing ortho-K lenses have previously been found to have greater likelihood of experiencing adverse events because of direct contact between the lens and ocular surface at night. Tear film stability and dynamic distribution are influenced by interaction between the tear film and ocular surface epithelium microvilli as well as the physiological environment of tears affecting the conjunctival epithelium. Inflammatory reactions in cases of AC can further affect ocular surface stability, thus creating a potential cause for the findings observed here. What’s more, it has been previously shown that those with indoor allergies, like positive dust mite reactions, also have on average more severe myopia, suggesting specific IgE levels for indoor allergens may be related to refractive error.

It is known that efficacy of ortho-K in terms of myopia control is influenced by factors that include age, spherical equivalent, pupil area and regularity of wear. This study demonstrated those with AC experienced more adverse events than those without AC, with these adverse events ultimately affecting continuity of ortho-K lens wear. Results indicated the number of nights skipped in lens wear was greater in the three years for those with AC than those without. Consequently, greater axial elongation in AC patients is likely associated with more frequent occurrence of corneal adverse events that led to extended periods of lens wear cessation.

The authors consider their findings and recommend that “when using ortho-K lenses to control myopia in patients with allergic conjunctivitis, it is crucial not only to ensure thorough communication and inform patients about the importance of timely follow-up, but also to focus on managing ocular inflammation.”

They add that “implementing timely and effective measures to control ocular inflammation can reduce the duration of lens wear cessation, thereby allowing ortho-k lenses to more effectively control the progression of myopia.”