Hello Ahmed,

From infectious point of view we made a research recently about the effect of poor hygiene practices in causing infections to the eye as contact lenses affect the normal flora found in the eyes. Moreover, we look for contact lens as a foreign body even it may resolve or treat some ophthalmological situations so you can predict a lot of complications related to it which affects the cornea.

I advice you to read the paper below which explains the pathophysiology of Contact lens on cornea and soon our paper will be available I hope you read it and give me your feedback.

Article Corneal pathophysiology of contact lenses

Article Disturbing the balance: effect of contact lens use on the oc...

This question can be answered in many different ways. It depends on the type of contact lens worn, duration and the material of the lens.

Soft contact lens with good Dk value and material of Silicone Hydrogel Polymers may have minimal side effects if worn with correct wearing regimen. They are very unlikely to change the refractive status of the eye.

RGP lenses: Provides better optics and corrects refractive error with high irregular astigmatism and are shown to change the refractive error in prolonged wear time.

Ortho K lenses: these lenses are solely designed to change the refractive errors of the eye. You can find so many research papers regarding the degree and type of correction they provide.

Hope this will help.

There are several different effects of a SCL more than a GP-CL on the cornea.

First, it is a source of direct toxicity or hypersensitivity reactions due to preservative solutions, antiseptics and other residual chemicals introduced while putting the lens on.

Second, it is a source of contamination and infection with microbes, particularly bacteria and fungi carried by the lens itself from a contaminated case, the wearer hands, among others.

Third, it is a physical barrier between the corneal epithelium and the environment. This barrier effect may induce epithelial cell hypoxia, may affect the apical epithelial cells metabolism, the shedding mechanism, microbe retention, and may induce epithelial erosions, predisposing the cornea to opportunistic infections.

Fourth, depending on the water content of the lens and the presence of aqueous deficient or evaporative dry eye, the CL may reduce significantly the lacrimal volume availability for lubrication and friction reduction while blinking, fro microbe and toxins clearance or wash out.

Finally, biofilm (cells debris, proteins, environment particles) stratification and build-up on the contact lens outer surface may become an complex antigenic structure, inducing a foreign body reaction and/or hypersensitivity response like the one seen in giant papillary conjunctivitis.

Please see the following RG links.

Article Contact Lens-related Complications: A Review

Article Effect of Contact Lens Wear on Cornea

Wearing contact lenses puts you at risk of several serious conditions including eye infections and corneal ulcers. These conditions can develop very quickly and can be very serious. In rare cases, these conditions can cause blindness.