Correction with night (hard) lenses

What are night lenses (orthokeratology lenses)?

The use of special night gas-permeable lenses is one of the most effective methods of temporary vision correction. Instead of wearing glasses or daily contact lenses, scientists have proposed a new method called orthokeratology. Hence, the name of the lenses is orthokeratological (OCL).

This method involves use of rigid night lenses which change the curve of the corneal surface and provides a temporary recovery of normal refraction, so a person can do without glasses and lenses for one to two days. 

How it works?

The ophthalmologist selects lenses for the patient with a special geometry of the back surface to be worn overnight. In the process of their use, hydrodynamic forces act in the lacrimal layer under the lenses, which causes flattening the epithelium in the central area and its thickening at the periphery of the cornea. In simple terms, under the pressure of the lens, the shape (architectonics) of the corneal surface changes temporarily, with the eyes with myopia, farsightedness or astigmatism begin to see correctly.

Note! Night lenses are used while sleeping. The recommended wearing time is 7-8 hours. Lens care involves daily cleaning and storage in a special solution. The shelf life of such lenses is 1 year. 

How long can you go without lenses?

The effect lasts until the epithelium regains its original geometry (on average 24-72 hours), after which orthokeratological lenses should be put on again.

How safe is the method?

Experience has shown that orthokeratology does not have a negative effect on the cornea. Moreover, in addition to providing temporary vision correction, orthokeratological lenses inhibit development of myopia in children and teens. The studies have confirmed improvements in the reflection characteristics of the eyes.

To avoid side effects and complications such as conjunctivitis or microbial keratitis, you should follow all recommendations of your doctor and regularly undergo preventive examinations.       

At what age is correction with night lenses possible?

Orthokeratological lenses are prescribed for adults and children. Small patients should use them from the age of six. When prescribing OCL for adults, the doctor takes into account age-related changes due to tear production.

The expediency of using orthokeratology in each case is determined individually. This method is suitable for patients with:

• progressive myopia (visual acuity up to -7 dioptres);   
• hyperopia (night lenses are effective for visual acuity up to +4 dioptres);
• false myopia;
• slight astigmatism (up to 1.75 dpt);
• amblyopia (lazy eye syndrome).

Why is using night lenses better than wearing day lenses?

This option is suitable in cases where the use of daytime lenses is inconvenient or impossible, for example, during water procedures or sports activities. This method of vision correction is also relevant for people of some professions – firefighters, drivers, etc.

Wearing the OCL is convenient and effective in paediatric practice: during the day, the child rubs the eyes, can bring in dirt or lose lenses during active games. All these problems are excluded during the night use. 

How are night lenses selected?

Orthokeratological lenses are selected by the doctor, who should take into account individual needs and wishes of the patient.

• First, a comprehensive ophthalmological examination is performed, with the causes and degree of visual acuity impairment, as well as the condition of the visual organ, determined. In addition, the doctor should ensure that the patient has no precautions to the use of OCL. The examination can take 1.5-2 hours.
• According to the results of the examination, the doctor performs calculations and selection of lenses. Keratograph, on which 3D modelling of the corneal surface is performed, enables to ensure high measurement accuracy. Proper lenses are selected for a particular patient using a computer program. The doctor performs fitting of the lenses, with their trial wearing by the patient.   
• An obligatory stage is patient training: the ophthalmologist explains how to use the lenses properly (put on, take off) and how to care for them. If orthokeratological lenses are prescribed to children, parents should learn how to make all the above manipulations.
• Correction by the method of orthokeratology provides for control examinations, with the frequency determined by the doctor. The patient is offered an individual visit plan (usually for 1 year).

Note! It will take some time to get used to OCL. The adaptation period is on average 5–7 days. 

Precautions to the use of orthokeratological lenses

Among the main limitations for the use of OCL are inflammatory eye diseases and eyelids, dystrophic diseases of the cornea. This method of vision correction is not used in patients with endocrine and oncological diseases, immune deficiency and infectious diseases. Lenses are not used for dry eyes, in patients with one eye, as well as when taking certain medications (corticosteroids, etc.).

Prices for orthokeratological lenses at the Ocular clinic

The Ocular Institute of Ophthalmology uses optics from the world’s leading manufacturers. Depending on the peculiarities of the visual disorder, the doctor may recommend standard, individual or customized night lenses.