Clear vision during the day without wearing glasses.

The safety of OK lenses is not an absolute concept but depends on various factors. Wearing any type of contact lens increases the risk of eye infections, inflammation, and injury, without exception. Ensuring the long-term safety of OK lenses mainly depends on three factors: 1) Proper lens fitting (such as centering the lens, ensuring the cornea evenly bears the weight of the lens, and allowing sufficient tear exchange); 2) Strict adherence to wearing and care routines; 3) Regular follow-up visits to detect and address any minor issues promptly, avoiding the development of more serious complications. If these three aspects are ensured, the long-term safety of wearing OK lenses is very high.

The risk of serious complications associated with long-term wear of OK lenses depends on several factors:

• Lens material: Comparatively, hard lens materials are safer than soft lenses. Hard lenses do not contain water, which almost eliminates the risk of pathogens breeding on the lens surface. Additionally, the fitting of hard lenses typically involves greater movement on the corneal surface, reducing the risk of pathogen adherence and subsequent infection.
• Wearing schedule:The risk of complications is lower with daytime wear compared to overnight wear. Daytime lens wear involves blinking and increased tear exchange, which improves safety. In contrast, overnight wear significantly reduces tear exchange and decreases lens movement, increasing the risk of pathogen infection.
• Fitting condition: Good lens fitting is essential, particularly for orthokeratology (OK) lens treatment. Proper patient selection, the optometrist's expertise in lens design, and ample clinical experience are crucial factors for achieving a good fit. Patient compliance with wearing and care: Contact lenses are medical devices placed directly on the ocular surface. Rough handling, careless care routines, and forcing lens wear despite warning signs from the eyes are the main causes of complications.

If the care routine for OK lenses is mastered, it should not take more than 5 minutes per day, with 2-3 minutes in the morning and evening, but consistency is crucial. Ensuring the long-term safety of wearing OK lenses requires three elements: appropriate lens handling, meticulous care, and regular follow-up visits. Specifically, lens handling should be done with care, and care routines should be thorough. Additionally, regular follow-up visits are essential. Poor lens fitting or improper use and care can lead to serious consequences. For example, inadequate lens cleaning with deposits or biofilm formation can cause chronic inflammation, especially allergic inflammation. Severe improper care, such as failing to detect surface cracks or small defects during lens handling, can result in corneal damage when the lens is worn. Although hard lens materials are less prone to pathogen growth, if there is a thick biofilm on the lens surface due to poor cleanliness, the biofilm itself can act as a breeding ground for bacteria. Therefore, if the lens is not clean and there are micro traumas on the cornea, combined with viscous tears during overnight wear and reduced lens movement, the risk of corneal inflammation and infection increases significantly.

After wearing OK lenses, the cornea is reshaped into a unique multifocal lens. This lens ensures clear imaging in the central area of the retina, providing good daytime unaided distance vision. At the same time, the multifocal lens effect on the cornea may generate a strong "myopia control signal" in the retina, slowing down the elongation rate of the eyeball and reducing myopia progression.

The effectiveness of myopia control with OK lenses varies among individuals but, on average, it can achieve approximately 50% control. This means that in a group of children wearing OK lenses, the average axial growth rate is about half that of the same-age control group wearing regular eyeglasses.

When a child's unaided visual acuity reaches 20/40, wearing OK lenses can provide a significant improvement in daytime unaided vision, motivating the child to comply with the treatment. The degree of myopia corresponding to a visual acuity of 20/40 can vary significantly among individuals, generally ranging from -0.50D to -1.0D. If the myopia degree is too low and the unaided visual acuity is better than 20/40, the child's desire to wear glasses is usually not strong, and treatment compliance may be poor.

It depends on the severity of eye-related allergy symptoms. If the allergy is severe, causing significant eye redness, roughness of the conjunctiva (inner surface of the eyelids), and severe itching with constant eye rubbing, it may not be suitable to wear OK lenses, and treatment for allergies should be addressed first. For mild cases, continued lens wear may be considered, but lens care, especially the rubbing step, should be performed diligently, as individuals with allergic conjunctivitis tend to have higher protein secretion in their tears, which can form a biofilm on the lens surface. Apart from absolute contraindications for treatment (such as irregular corneas or active inflammation), OK lenses may not be suitable for patients with high degrees of myopia, small and tight eyelid fissures that make lens insertion difficult, extreme anxiety during lens handling, or poor compliance with lens use and care.

The baseline age for starting OK lens treatment is generally 7-12 years old. However, being younger than this age range is not an absolute contraindication for OK lens treatment. Whether younger patients are suitable for OK lens treatment depends on various subjective and objective factors. The subjective factors mainly consider the following points: 1) the child's psychological maturity, which refers to whether they can understand the purpose of OK lenses and are willing to overcome the initial discomfort of wearing them; 2) whether the child has a strong desire to wear glasses (usually a desire to be free from wearing regular glasses during the day); 3) the ability to effectively communicate any problems to their parents. If a young child meets all three conditions, experienced doctors generally do not consider the child's physiological age as an absolute indicator of whether OK lenses can be prescribed. It is worth noting that there is no upper age limit for OK lens treatment. However, since adults have higher visual quality requirements, are more sensitive to glare, ghosting, and other visual disturbances, and have higher visual demands for nighttime driving, OK lenses are more suitable for adults with lower degrees of myopia. This is because the degree of glare and myopia reduction are positively correlated. Regardless of the brand or design of OK lenses, the success rate of fully correcting myopia and the baseline degree of myopia are generally inversely proportional. In other words, the lower the degree of myopia, the less corneal reshaping is required, making the fitting process easier. For children with myopia below 400 degrees, the probability of achieving a daytime uncorrected visual acuity of 0.8 (20/25) or higher exceeds 80%. However, for children with 600 degrees of myopia, the probability of achieving complete correction with OK lenses is less than 50%, and there is a significantly increased risk of corneal surface microdamage. There is no specific range of astigmatism for OK lens use. It depends on the nature of astigmatism (whether it is corneal or lenticular in origin), the influence of corneal shape on lens fitting, the impact of residual astigmatism on uncorrected visual acuity, the patient's expectations, lens design choices, and the doctor's experience, among other factors.

OK lens treatment is a long-term and continuous method of myopia management. The complexity of fitting, the special nature of corneal reshaping and overnight lens wear, and the long-term nature of treatment make the careful selection of an OK lens doctor and clinic particularly important. Additionally, OK lens treatment can be costly, so it is important for parents to have comprehensive communication with the doctor regarding treatment expectations, costs, and other important factors to ensure mutual agreement. When signing the fitting agreement, it is crucial to read it carefully, clarify any doubts, and then sign it. Specifically, the selection of an OK lens doctor should primarily consider the following factors:

• Relevant experience and knowledge of the fitting doctor.
• Ability to communicate effectively with children.
• Difficulty in scheduling appointments on weekends.
• Clinic facilities.
• Transparency of fees.

The annual cost of OK lenses can vary significantly among different clinics. Generally, the initial fitting cost for OK lenses in the first year ranges from $2000 to $2500, and the cost of lens materials itself is between $500 and $800 per pair. It is important to emphasize that the fee structure for OK lenses differs between the United States and other countries. In most U.S. clinics, the service fee for OK lens treatment (including the doctor's time and expertise) and the cost of lenses are separate. Additionally, there may be costs associated with related care products.

If the lenses are well cared for and there is no significant increase in myopia, OK lenses can be used for approximately 1-1.5 years without significant changes in lens fitting.

Regular follow-up visits for OK lenses are crucial. The first follow-up visit after overnight lens wear is generally scheduled as early in the morning as possible, and it requires the child to wear the lenses for examination to detect any fitting issues or subtle corneal damage that may have occurred during overnight lens wear. If the first follow-up visit goes well, wearing the lenses during the weekly follow-up may not be necessary. However, if any issues are identified during the first follow-up, lens adjustments may be needed, and the child may be asked to wear the lenses during the weekly visit for observation before removing them at the clinic.

Under what circumstances should it be suspended long-term? There can be several reasons for temporarily suspending OK lens wear, with the most common one being poor lens fitting. If the lenses become increasingly misaligned over time, it may be necessary to have the child stop wearing them for a few nights to allow the cornea's eccentric shape to return to a state that won't affect the fitting of the next lens. This is the most common reason for temporary suspension. Additionally, if there is any damage to the corneal epithelium, it may be necessary to stop wearing the lenses to allow the cornea to fully repair before resuming lens wear. Long-term suspension, which is the most severe and least desirable situation, can occur due to the occurrence of corneal infections. Even if a corneal ulcer fully heals and there is no scarring on the corneal surface, most doctors do not recommend resuming lens wear. In addition, if OK lenses are not effectively controlling myopia or if there are other reasons leading to poor daytime visual correction, the doctor may recommend alternative options.

There is currently no definitive answer regarding whether there is a rebound effect on myopia control after temporarily stopping OK lens wear. One reason is that after stopping OK lens wear, myopia may increase due to the corneal curvature rebounding (gradually becoming steeper from a flattened state caused by reshaping). This process can last for several months or even over a year. During this lengthy period, it is challenging to accurately quantify whether myopia deepens due to corneal shape restoration or if it is due to the combination of corneal shape restoration and accelerated axial elongation. Additionally, if OK lenses are stopped prematurely (i.e., before myopia has completely stabilized), axial elongation may continue, but this represents ongoing myopia progression rather than rebound after stopping lens wear. In summary, there is currently no reliable evidence to support the notion that stopping OK lens wear leads to rebound myopia development.

Clinical trials are currently underway to study the synergistic effects of combining orthokeratology or spectacle lenses with atropine eye drops for myopia control. This approach may be suitable for children with rapidly progressing myopia, high degrees of myopia, or children with both parents being myopic. Currently, optical and pharmacological interventions used in animal models have shown some additive effects, but the exact mechanisms underlying the synergistic effects are not yet fully understood.

There is a possibility, but it is extremely rare. OK lens materials themselves are quite resilient, so lens fragmentation usually occurs when external forces act on lenses that already have noticeable defects (such as deeper or longer scratches on the surface). In such cases, the most fragile part of the lens may shatter under significant pressure and end up inside the eye. However, at the same time, the cornea has strong resilience, and in the case of fractures in gas-permeable lens materials, severe irreparable cuts to the cornea are generally unlikely to occur.

Contact lens care systems for OK lenses can be broadly divided into multipurpose solutions and hydrogen peroxide systems. Multipurpose solutions usually contain surfactants (for rubbing the lens, removing deposits), disinfectants (to eliminate microbial pathogens on the lens surface), conditioning agents (to enhance lens surface wetting), and other additional components such as buffering salts. Multipurpose solutions are very convenient to use, as they combine lens rubbing, rinsing, and soaking functions in one solution, usually without the need for additional products. Hydrogen peroxide solutions are care systems that use 3% hydrogen peroxide as the active ingredient. These solutions require special lens cases or enzymatic additives to neutralize hydrogen peroxide in a timed and measured manner. Hydrogen peroxide solutions have excellent antimicrobial properties, particularly against fungi and Acanthamoeba. Additionally, when completely neutralized, the solution does not cause eye irritation due to preservatives when it comes into contact with the ocular surface. The main limitation of hydrogen peroxide solutions is the need for neutralization, and once (soft) contact lenses are placed in the solution, they cannot be immediately removed and worn, as it can cause intense irritation. Thus, hydrogen peroxide solutions are not suitable for situations such as removing lenses for daytime napping. It is important to note that when using hydrogen peroxide solutions, the step of rubbing and rinsing the lenses with the solution should not be omitted. While hydrogen peroxide solutions effectively kill microbial pathogens, they cannot ensure thorough removal of lens surface deposits through soaking alone.

Currently, there is no randomized controlled clinical trial providing evidence of different designs of OK lenses having differential effects on myopia control. Most clinical studies reporting better myopia control effects for a particular brand are retrospective in design, which means they selectively analyze a subset of cases from a larger sample. Retrospective studies have a high risk of sampling bias, so the results obtained can only provide reference for future prospective studies with larger sample sizes and cannot establish a causal relationship. It is important to note that the selection of a suitable brand or design should not be the decision of the parents but rather the prescribing doctor, based on the patient's specific condition, the doctor's experience with different designs, and their understanding of various options. The doctor's choice of brand depends on several factors: their familiarity with a particular brand/design, knowing its potential and how to adjust parameters in case of any issues; the warranty period provided by the manufacturer, as some brands offer more flexibility in parameter adjustments within a certain period; and the profitability of the lenses. These factors are considered by the doctor, and it is not the role of parents to select the brand.

There could be two reasons for this. First, when replicating an exact copy of a lens, there are around twenty parameters, but the prescription record provided to parents or documented in the case may only include seven or eight of them. Therefore, having the same values for these seven or eight parameters does not guarantee that the new lenses will have the exact same shape as the previous ones. The second reason is related to the individual patient's lenses. After wearing lenses for a long time, the lenses and the cornea have undergone a certain degree of adaptation. When new lenses with the same parameters are fitted, the lens shape is actually slightly different from the lenses worn for two years. These subtle changes in lens shape can lead to a decrease in visual acuity (similar to the difference in sensation between well-worn shoes and a new pair of the same model).

The visual acuity with lenses and without lenses during an OK lens examination reflects different aspects of OK lens wear. The lenses themselves have power, so visual acuity with lenses is influenced by the fit between the lenses and the cornea (the shape of the lens on the cornea's anterior surface) and the shape of the cornea. On the other hand, post-treatment unaided visual acuity (without lenses) is only affected by the cornea's shape after orthokeratology treatment. There is no direct relationship between the two. Good visual acuity with lenses does not necessarily mean good unaided visual acuity, and poor visual acuity with lenses does not necessarily mean that the desired unaided visual acuity cannot be achieved. The evaluation should be made in consultation with the prescribing doctor.

An ideal OK lens fitting should meet three main principles: 1) an appropriate lens diameter, 2) good centration on the cornea, and 3) adequate movement, especially when lenses are removed in the morning after overnight wear. The lenses should have a certain degree of movement on the corneal surface, rather than adhering to it.

• Parents can try wearing contact lenses themselves to have a firsthand experience, which can help them assist their children better.
• Explain to the child the pros and cons of wearing OK lenses and establish realistic expectations.
• Communicate with other children who are already wearing OK lenses and encourage them to share their experiences.

The use of topical anesthesia can make the initial wearing experience more comfortable for both the child and the parent. However, topical anesthesia only numbs the surface of the cornea. The feeling of foreign body sensation when wearing OK lenses primarily arises from the friction between the lens and the upper eyelid, rather than the cornea's sensation. This foreign body sensation cannot be completely eliminated by topical anesthesia. Therefore, many children still experience some degree of foreign body sensation even with topical anesthesia. The main benefit of topical anesthesia is its psychological comforting effect to alleviate anxiety. Importantly, after the use of topical anesthesia, the child's perception of the normal baseline sensation during initial lens wear is affected. When they encounter foreign body sensations at home, they may struggle to differentiate between normal sensations during initial wear and discomfort caused by inadequate lens cleaning or improper insertion technique, which can hinder problem-solving abilities. Although the use of topical anesthesia is ultimately the doctor's decision, it does not significantly increase the success rate of initial lens wear.

The assessment of OK lens positioning cannot be accurately evaluated without a professional slit lamp biomicroscope. Most parents' notion of the "correct position" may refer to whether the lens is placed on the cornea or if the lens and the iris (cornea) form a perfect concentric relationship. There is a significant difference between the curvature of the cornea and the sclera (white of the eye). If the OK lens is completely misaligned and ends up on the sclera instead of the cornea, which is much flatter, the lens is likely to be adsorbed onto the sclera. In such cases, the lens cannot be repositioned on the cornea by blinking or pushing it with a finger. Therefore, if the entire lens is stuck on the sclera, it needs to be removed, cleaned, and rechecked. Once it is confirmed that there are no issues with the lens, it can be reinserted. However, if a part of the lens is placed on the cornea during insertion, even if it is slightly off-center, as long as the parameters are appropriate, the lens will eventually find its correct position on the cornea (and automatically reset). Closing the eyes or performing gentle maneuvers does not significantly aid in the lens resetting process. Once a portion of the lens is on the cornea, it will reset whether you blink or close your eyes.

If we compare contact lens rewetting drops from over 10 years ago to artificial tears, they had clear differences in their formulations, so they couldn't be used interchangeably. Nowadays, the formulations of contact lens rewetting drops and artificial tears have become increasingly similar, but for safety reasons, it is still better to use artificial tears in conjunction with OK lens wear. As a filling solution for OK lenses before insertion, it is advisable to avoid using high-viscosity products (such as gels) or lipid-based artificial tears (such as Optive Mega-3) as they can interfere with lens fitting or lead to more deposits on the lens surface.

In principle, during the acute phase of eyelid meibomian gland inflammation (chalazion), OK lens wear should be discontinued. However, after the acute phase, if the lump is very small, without redness, pain, tenderness, obvious secretions, and there is no discomfort while wearing the OK lens, and normal vision is restored after removing the lens, it is permissible to continue wearing the lens with the doctor's approval.

Hydrogen peroxide has a significant toxic reaction to the corneal epithelial cells, so when it comes into contact with the eyes, it feels like getting chili water sprayed into the eyes, causing an obvious stinging sensation. Fortunately, the toxic reaction caused by hydrogen peroxide on the corneal epithelium generally recovers completely within 24 to 48 hours, and it does not cause any permanent damage to the eyes. Apart from the initial discomfort, there should not be any other major issues.

If the lenses are thoroughly rubbed every day, using Progent (AB solution) once every quarter can effectively remove deposits from the lens surface.

The effect of OK lenses on myopia control varies greatly among individuals. Most children using OK lenses still experience some degree of axial elongation. Whether it is due to suboptimal lens design can only be determined after specific examinations. The exact degree of myopia correction with OK lenses cannot be accurately measured, so the claim of an annual increase of -0.25 diopters may not be reliable. The control effect needs to be evaluated comprehensively by considering changes in axial length.

Firstly, we need to clarify the concept of myopia control effectiveness. It is not a binary indicator (yes or no), but rather a measure of the degree of effectiveness. Currently, based on several clinical trials, we can see that, on average, OK lenses can achieve a reduction of approximately 50% in axial elongation. How is 50% defined? If we compare children wearing OK lenses with those wearing single-vision eyeglasses, for example, if the average annual increase in axial length for children wearing single-vision eyeglasses is 0.3mm, and for those wearing OK lenses it is 0.15mm, then we have achieved a 50% control effect. However, there are two points that need to be explained. First, there is significant individual variation in the effectiveness of OK lenses for myopia control. While the average effect is 50%, the standard deviation is quite large. Some children may wear OK lenses for many years without significant changes in prescription or axial length, while others may not achieve the average control effect observed in clinical trials. However, this does not necessarily indicate no effect because it is impossible to determine the extent of myopia progression without any form of myopia control intervention. The fitting of OK lenses is one of the main factors influencing the control effect. Simply wearing OK lenses does not guarantee the same control effect for everyone. If the lens parameters are chosen improperly or if corneal reshaping is not sufficient, the child may have poor uncorrected visual acuity during the day. Prolonged periods of poor vision can be a significant stimulus for axial elongation. Therefore, the control effect of OK lenses can be affected if a child wears them for a long time without achieving good uncorrected visual acuity. Apart from proper OK lens fitting, the most significant determining factor for effectiveness is the proportion of genetic factors involved in a child's myopia progression. Generally, the earlier the onset of myopia in a child, the higher the proportion of genetic factors in the development of myopia, the faster the progression, and the poorer the effect of later interventions. This conclusion applies to all intervention methods, including OK lenses, multifocal soft lenses, or atropine eye drops.

It's important to note that using OK lenses doesn't eliminate the influence of a child's visual habits on myopia progression. Good eye hygiene, sufficient visual relaxation, and outdoor activities are still essential for myopia control.

If a child only has myopia without other issues such as strabismus or significant refractive errors, the likelihood of developing amblyopia is very low. If a child is diagnosed with amblyopia along with -3.00 diopters of myopia, it is advisable to seek a second medical opinion to exclude other factors that may cause poor visual acuity.

No, OK lenses only inhibit non-physiological axial elongation caused by poor visual environments. Eye development and axial elongation accompanying bodily growth (especially height) do not increase the risk of retinal diseases. Whether the axial length continues to increase after discontinuing OK lens wear primarily depends on the intensity of eye usage. Although the plasticity of eye shape decreases with age, and the rate of axial elongation slows down, the protective effect of age is not absolute. There are cases in adult myopic individuals where, due to a period of high-intensity eye usage, worsening of myopia resumes after many years of stability.

Dry spots are not a specific description, so the diagnostic significance is limited. If there is a feeling of eye dryness after wearing OK lenses, it is important to first exclude micro-injuries to the corneal epithelium caused by fitting issues or lens defects. The use of artificial tears can help alleviate eye dryness, but it is crucial to address corneal epithelial damage caused by fitting or lens issues fundamentally, rather than relying solely on artificial tears to relieve symptoms.

The clarity of vision can be assessed objectively and subjectively. Objectively, if a patient wearing OK lenses can achieve 20/30 or better in one eye by the afternoon or before going to bed, it is generally considered clinically acceptable. This level of clarity does not significantly affect the effectiveness of myopia control treatment. Subjectively, the perception of clear vision depends on the child's individual visual needs and age. For children around seven to eight years old, their overall visual demands may not be very high, so even if the objective visual acuity is the same, they may not perceive it as blurry. However, for a teenager who has just started driving, the same level of visual acuity may cause noticeable glare at night and affect driving confidence. Therefore, subjective visual clarity depends on the age and specific visual demands of the wearer.

The ideal time for follow-up appointments depends on the main purpose. In the initial phase of OK lens fitting (within the first 1-2 weeks of wearing), follow-up appointments primarily focus on: 1) evaluating the lens fit; 2) checking for any adverse reactions of the cornea and conjunctiva; 3) assessing the daytime unaided visual acuity; and 4) ensuring proper lens care. Considering these factors, it is easier to observe lens fit issues and minor corneal injuries in the morning. Minor corneal injuries repair rapidly, and if they have already healed by the afternoon examination, the doctor may not be able to detect these subtle conditions. Therefore, in general, we recommend morning follow-up appointments on the first day and first week of lens fitting. After entering the stable phase of fitting, follow-up appointments focus on: 1) checking for any regression in daytime visual acuity; 2) monitoring myopia/axial progression; and 3) evaluating any changes in fitting. During this phase, afternoon appointments are more effective in detecting visual regression and other issues. As axial length exhibits biological rhythmicity, regular check-ups every quarter should be scheduled at similar times to ensure the comparability of biometric data. Overall, in the initial phase, morning appointments are recommended, while subsequent check-ups offer more flexibility. However, if parents or children subjectively feel that their vision is better in the morning compared to the afternoon, it is advisable to have the appointment in the afternoon to assess the adequacy of vision during those times.

The sensation of the lenses and their movement reported by parents or experienced by children themselves after lens wear is not a highly accurate indicator of ideal lens fitting. The most important indicators are the dynamic evaluation during lens wear with fluorescein staining in the clinic and the corneal topography and eye health assessment after lens removal, which are the most accurate and objective indicators. It is normal for lenses to exhibit different levels of movement or sensations between the left and right eyes even in cases where both eyes are well-adapted. However, if the lenses are poorly fitted, resulting in one lens blinking off the eye with every blink or one lens frequently moving while the other remains stable, these situations do indicate fitting issues. In general, subjective sensations such as lens movement or foreign body sensations are not reliable indicators of the quality of lens fitting.

Not necessarily. Different lens designs can result in different sensations when removing the lenses. Typically, if the baseline myopia is higher and requires more significant corneal reshaping, the lens design may tend to have a higher level of vaulting around the cornea, meaning the lens fits tightly against the cornea. In such cases, lenses can be more challenging to remove, especially in the morning. The difficulty of lens removal depends on various factors, including specific techniques, the presence of corneal injuries after lens removal, and the overall effectiveness of the reshaping. However, in general, it is common for lenses to fit tightly in cases of astigmatism or relatively high degrees of myopia.

Let's talk about the parameters for OK lens fitting. The parameters for OK lens fitting depend on the shape of the child's cornea and the baseline level of myopia and astigmatism. To achieve the desired fitting effect, it is important for the lens to have excellent centration and good mobility. These factors are mainly related to the corneal curvature, and sufficient flattening of the central cornea is also necessary. The degree of flattening depends on the level of baseline myopia. In other words, the higher the myopia before starting lens wear, the greater the force required for corneal shaping in the central cornea. Other considerations include the child's sleep duration, whether they experience significant visual regression from morning to evening, and whether they need clear vision between 8 PM and 10 PM but experience visual regression. In some cases, it may be necessary to wear the OK lenses a few hours before bedtime to compensate for insufficient overnight sleep. In such cases, in addition to the degree of corneal shaping on the posterior surface of the lens, we also aim for clear and comfortable vision when wearing the lenses. If the lens power is not designed properly, it is possible to achieve sufficient corneal shaping, but the visual comfort may be compromised. Therefore, OK lenses themselves have a prescription. However, the correlation between the lens power and corneal shaping is not necessarily direct. Two lenses can have identical corneal shaping effects on the posterior surface, but the anterior surface curvature may be different, resulting in the same corneal shaping effect but different visual outcomes for the wearer. To sum up, OK lenses do have a prescription, which is also related to the shape of the child's cornea. The need for replacement depends on the stability of the prescription and the condition of lens care.

If the uncorrected visual acuity of the myopic eye is worse than 0.5 or 20/40, wearing OK lenses can significantly improve vision and increase the child's willingness to wear them. However, if the uncorrected visual acuity of the myopic eye is still relatively good, for example, if they can still see 20/30, and the child does not perceive a significant improvement in vision with OK lenses, their willingness to wear the lenses may be low. Additionally, consideration should be given to the prescription of the other eye. Generally, fitting OK lenses for one eye only requires the child to understand that OK lenses not only correct vision but also have a role in controlling myopia progression. If the child does not grasp this concept and relies mainly on the other eye for distance vision, they may not see a significant benefit from wearing OK lenses, leading to poor compliance.

• Regular visual acuity checks: Assess the visual acuity of both eyes while wearing the OK lenses.
• Corneal topography: Monitor corneal shape and changes to ensure the lenses fit properly and are not causing any adverse effects on the cornea.
• Slit-lamp examination: Check the health of the cornea, conjunctiva, and other anterior eye structures.
• Intraocular pressure measurement: Monitor intraocular pressure to ensure it remains within a normal range.
• Refraction: Regularly evaluate the refractive status of the eyes to determine any changes in prescription.
• Follow-up consultations: Schedule regular follow-up appointments with the eye care professional who prescribed the OK lenses. These appointments allow for discussions about treatment progress, adjustments to the lens fitting if needed, and addressing any concerns or questions related to the treatment or eye health.

Increased redness and bloodshot appearance of the eyes can occur after wearing OK lenses, especially during the initial adaptation period. This is mainly due to corneal molding and tear film changes caused by the lens. To prevent or minimize this discomfort, it is important to follow proper lens care and hygiene practices, such as:

• Ensuring the lenses are properly cleaned and disinfected before insertion.
• Using lubricating eye drops as recommended by your eye care professional to maintain a healthy tear film.
• Avoiding wearing lenses for extended periods without breaks.
• Keeping the lenses and lens case clean to prevent contamination.

Punctate epithelial staining is a common occurrence in OK lens wearers. Mild point staining usually does not require discontinuation of lens wear or specific treatment. However, if the staining becomes severe or is associated with discomfort, it is important to consult with an eye care professional for appropriate management and guidance.